summaryrefslogtreecommitdiffstats
path: root/src/verify.c
blob: 262a8d76af39ef7ec55247a0b211d554637fcf2a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Copyright (c) University of Cambridge 1995 - 2018 */
/* Copyright (c) The Exim Maintainers 2020 */
/* See the file NOTICE for conditions of use and distribution. */

/* Functions concerned with verifying things. The original code for callout
caching was contributed by Kevin Fleming (but I hacked it around a bit). */


#include "exim.h"
#include "transports/smtp.h"

#define CUTTHROUGH_CMD_TIMEOUT  30	/* timeout for cutthrough-routing calls */
#define CUTTHROUGH_DATA_TIMEOUT 60	/* timeout for cutthrough-routing calls */
static smtp_context ctctx;
uschar ctbuffer[8192];


/* Structure for caching DNSBL lookups */

typedef struct dnsbl_cache_block {
  time_t expiry;
  dns_address *rhs;
  uschar *text;
  int rc;
  BOOL text_set;
} dnsbl_cache_block;


/* Anchor for DNSBL cache */

static tree_node *dnsbl_cache = NULL;


/* Bits for match_type in one_check_dnsbl() */

#define MT_NOT 1
#define MT_ALL 2

static uschar cutthrough_response(client_conn_ctx *, char, uschar **, int);



/*************************************************
*          Retrieve a callout cache record       *
*************************************************/

/* If a record exists, check whether it has expired.

Arguments:
  dbm_file          an open hints file
  key               the record key
  type              "address" or "domain"
  positive_expire   expire time for positive records
  negative_expire   expire time for negative records

Returns:            the cache record if a non-expired one exists, else NULL
*/

static dbdata_callout_cache *
get_callout_cache_record(open_db *dbm_file, const uschar *key, uschar *type,
  int positive_expire, int negative_expire)
{
BOOL negative;
int length, expire;
time_t now;
dbdata_callout_cache *cache_record;

if (!(cache_record = dbfn_read_with_length(dbm_file, key, &length)))
  {
  HDEBUG(D_verify) debug_printf("callout cache: no %s record found for %s\n", type, key);
  return NULL;
  }

/* We treat a record as "negative" if its result field is not positive, or if
it is a domain record and the postmaster field is negative. */

negative = cache_record->result != ccache_accept ||
  (type[0] == 'd' && cache_record->postmaster_result == ccache_reject);
expire = negative? negative_expire : positive_expire;
now = time(NULL);

if (now - cache_record->time_stamp > expire)
  {
  HDEBUG(D_verify) debug_printf("callout cache: %s record expired for %s\n", type, key);
  return NULL;
  }

/* If this is a non-reject domain record, check for the obsolete format version
that doesn't have the postmaster and random timestamps, by looking at the
length. If so, copy it to a new-style block, replicating the record's
timestamp. Then check the additional timestamps. (There's no point wasting
effort if connections are rejected.) */

if (type[0] == 'd' && cache_record->result != ccache_reject)
  {
  if (length == sizeof(dbdata_callout_cache_obs))
    {
    dbdata_callout_cache *new = store_get(sizeof(dbdata_callout_cache), FALSE);
    memcpy(new, cache_record, length);
    new->postmaster_stamp = new->random_stamp = new->time_stamp;
    cache_record = new;
    }

  if (now - cache_record->postmaster_stamp > expire)
    cache_record->postmaster_result = ccache_unknown;

  if (now - cache_record->random_stamp > expire)
    cache_record->random_result = ccache_unknown;
  }

HDEBUG(D_verify) debug_printf("callout cache: found %s record for %s\n", type, key);
return cache_record;
}



/* Check the callout cache.
Options * pm_mailfrom may be modified by cache partial results.

Return: TRUE if result found
*/

static BOOL
cached_callout_lookup(address_item * addr, uschar * address_key,
  uschar * from_address, int * opt_ptr, uschar ** pm_ptr,
  int * yield, uschar ** failure_ptr,
  dbdata_callout_cache * new_domain_record, int * old_domain_res)
{
int options = *opt_ptr;
open_db dbblock;
open_db *dbm_file = NULL;

/* Open the callout cache database, it it exists, for reading only at this
stage, unless caching has been disabled. */

if (options & vopt_callout_no_cache)
  {
  HDEBUG(D_verify) debug_printf("callout cache: disabled by no_cache\n");
  }
else if (!(dbm_file = dbfn_open(US"callout", O_RDWR, &dbblock, FALSE, TRUE)))
  {
  HDEBUG(D_verify) debug_printf("callout cache: not available\n");
  }
else
  {
  /* If a cache database is available see if we can avoid the need to do an
  actual callout by making use of previously-obtained data. */

  dbdata_callout_cache_address * cache_address_record;
  dbdata_callout_cache * cache_record = get_callout_cache_record(dbm_file,
      addr->domain, US"domain",
      callout_cache_domain_positive_expire, callout_cache_domain_negative_expire);

  /* If an unexpired cache record was found for this domain, see if the callout
  process can be short-circuited. */

  if (cache_record)
    {
    /* In most cases, if an early command (up to and including MAIL FROM:<>)
    was rejected, there is no point carrying on. The callout fails. However, if
    we are doing a recipient verification with use_sender or use_postmaster
    set, a previous failure of MAIL FROM:<> doesn't count, because this time we
    will be using a non-empty sender. We have to remember this situation so as
    not to disturb the cached domain value if this whole verification succeeds
    (we don't want it turning into "accept"). */

    *old_domain_res = cache_record->result;

    if (  cache_record->result == ccache_reject
       || *from_address == 0 && cache_record->result == ccache_reject_mfnull)
      {
      HDEBUG(D_verify)
	debug_printf("callout cache: domain gave initial rejection, or "
	  "does not accept HELO or MAIL FROM:<>\n");
      setflag(addr, af_verify_nsfail);
      addr->user_message = US"(result of an earlier callout reused).";
      *yield = FAIL;
      *failure_ptr = US"mail";
      dbfn_close(dbm_file);
      return TRUE;
      }

    /* If a previous check on a "random" local part was accepted, we assume
    that the server does not do any checking on local parts. There is therefore
    no point in doing the callout, because it will always be successful. If a
    random check previously failed, arrange not to do it again, but preserve
    the data in the new record. If a random check is required but hasn't been
    done, skip the remaining cache processing. */

    if (options & vopt_callout_random) switch(cache_record->random_result)
      {
      case ccache_accept:
	HDEBUG(D_verify)
	  debug_printf("callout cache: domain accepts random addresses\n");
	*failure_ptr = US"random";
	dbfn_close(dbm_file);
	return TRUE;     /* Default yield is OK */

      case ccache_reject:
	HDEBUG(D_verify)
	  debug_printf("callout cache: domain rejects random addresses\n");
	*opt_ptr = options & ~vopt_callout_random;
	new_domain_record->random_result = ccache_reject;
	new_domain_record->random_stamp = cache_record->random_stamp;
	break;

      default:
	HDEBUG(D_verify)
	  debug_printf("callout cache: need to check random address handling "
	    "(not cached or cache expired)\n");
	dbfn_close(dbm_file);
	return FALSE;
      }

    /* If a postmaster check is requested, but there was a previous failure,
    there is again no point in carrying on. If a postmaster check is required,
    but has not been done before, we are going to have to do a callout, so skip
    remaining cache processing. */

    if (*pm_ptr)
      {
      if (cache_record->postmaster_result == ccache_reject)
	{
	setflag(addr, af_verify_pmfail);
	HDEBUG(D_verify)
	  debug_printf("callout cache: domain does not accept "
	    "RCPT TO:<postmaster@domain>\n");
	*yield = FAIL;
	*failure_ptr = US"postmaster";
	setflag(addr, af_verify_pmfail);
	addr->user_message = US"(result of earlier verification reused).";
	dbfn_close(dbm_file);
	return TRUE;
	}
      if (cache_record->postmaster_result == ccache_unknown)
	{
	HDEBUG(D_verify)
	  debug_printf("callout cache: need to check RCPT "
	    "TO:<postmaster@domain> (not cached or cache expired)\n");
	dbfn_close(dbm_file);
	return FALSE;
	}

      /* If cache says OK, set pm_mailfrom NULL to prevent a redundant
      postmaster check if the address itself has to be checked. Also ensure
      that the value in the cache record is preserved (with its old timestamp).
      */

      HDEBUG(D_verify) debug_printf("callout cache: domain accepts RCPT "
	"TO:<postmaster@domain>\n");
      *pm_ptr = NULL;
      new_domain_record->postmaster_result = ccache_accept;
      new_domain_record->postmaster_stamp = cache_record->postmaster_stamp;
      }
    }

  /* We can't give a result based on information about the domain. See if there
  is an unexpired cache record for this specific address (combined with the
  sender address if we are doing a recipient callout with a non-empty sender).
  */

  if (!(cache_address_record = (dbdata_callout_cache_address *)
    get_callout_cache_record(dbm_file, address_key, US"address",
      callout_cache_positive_expire, callout_cache_negative_expire)))
    {
    dbfn_close(dbm_file);
    return FALSE;
    }

  if (cache_address_record->result == ccache_accept)
    {
    HDEBUG(D_verify)
      debug_printf("callout cache: address record is positive\n");
    }
  else
    {
    HDEBUG(D_verify)
      debug_printf("callout cache: address record is negative\n");
    addr->user_message = US"Previous (cached) callout verification failure";
    *failure_ptr = US"recipient";
    *yield = FAIL;
    }

  /* Close the cache database while we actually do the callout for real. */

  dbfn_close(dbm_file);
  return TRUE;
  }
return FALSE;
}


/* Write results to callout cache
*/
static void
cache_callout_write(dbdata_callout_cache * dom_rec, const uschar * domain,
  int done, dbdata_callout_cache_address * addr_rec, uschar * address_key)
{
open_db dbblock;
open_db *dbm_file = NULL;

/* If we get here with done == TRUE, a successful callout happened, and yield
will be set OK or FAIL according to the response to the RCPT command.
Otherwise, we looped through the hosts but couldn't complete the business.
However, there may be domain-specific information to cache in both cases.

The value of the result field in the new_domain record is ccache_unknown if
there was an error before or with MAIL FROM:, and errno was not zero,
implying some kind of I/O error. We don't want to write the cache in that case.
Otherwise the value is ccache_accept, ccache_reject, or ccache_reject_mfnull. */

if (dom_rec->result != ccache_unknown)
  if (!(dbm_file = dbfn_open(US"callout", O_RDWR|O_CREAT, &dbblock, FALSE, TRUE)))
    {
    HDEBUG(D_verify) debug_printf("callout cache: not available\n");
    }
  else
    {
    (void)dbfn_write(dbm_file, domain, dom_rec,
      (int)sizeof(dbdata_callout_cache));
    HDEBUG(D_verify) debug_printf("wrote callout cache domain record for %s:\n"
      "  result=%d postmaster=%d random=%d\n",
      domain,
      dom_rec->result,
      dom_rec->postmaster_result,
      dom_rec->random_result);
    }

/* If a definite result was obtained for the callout, cache it unless caching
is disabled. */

if (done  &&  addr_rec->result != ccache_unknown)
  {
  if (!dbm_file)
    dbm_file = dbfn_open(US"callout", O_RDWR|O_CREAT, &dbblock, FALSE, TRUE);
  if (!dbm_file)
    {
    HDEBUG(D_verify) debug_printf("no callout cache available\n");
    }
  else
    {
    (void)dbfn_write(dbm_file, address_key, addr_rec,
      (int)sizeof(dbdata_callout_cache_address));
    HDEBUG(D_verify) debug_printf("wrote %s callout cache address record for %s\n",
      addr_rec->result == ccache_accept ? "positive" : "negative",
      address_key);
    }
  }

if (dbm_file) dbfn_close(dbm_file);
}


/* Cutthrough-multi.  If the existing cached cutthrough connection matches
the one we would make for a subsequent recipient, use it.  Send the RCPT TO
and check the result, nonpipelined as it may be wanted immediately for
recipient-verification.

It seems simpler to deal with this case separately from the main callout loop.
We will need to remember it has sent, or not, so that rcpt-acl tail code
can do it there for the non-rcpt-verify case.  For this we keep an addresscount.

Return: TRUE for a definitive result for the recipient
*/
static int
cutthrough_multi(address_item * addr, host_item * host_list,
  transport_feedback * tf, int * yield)
{
BOOL done = FALSE;

if (addr->transport == cutthrough.addr.transport)
  for (host_item * host = host_list; host; host = host->next)
    if (Ustrcmp(host->address, cutthrough.host.address) == 0)
      {
      int host_af;
      uschar *interface = NULL;  /* Outgoing interface to use; NULL => any */
      int port = 25;

      deliver_host = host->name;
      deliver_host_address = host->address;
      deliver_host_port = host->port;
      deliver_domain = addr->domain;
      transport_name = addr->transport->name;

      host_af = Ustrchr(host->address, ':') ? AF_INET6 : AF_INET;

      if (  !smtp_get_interface(tf->interface, host_af, addr, &interface,
	      US"callout")
	 || !smtp_get_port(tf->port, addr, &port, US"callout")
	 )
	log_write(0, LOG_MAIN|LOG_PANIC, "<%s>: %s", addr->address,
	  addr->message);

      smtp_port_for_connect(host, port);

      if (  (  interface == cutthrough.interface
	    || (  interface
	       && cutthrough.interface
	       && Ustrcmp(interface, cutthrough.interface) == 0
	    )  )
	 && host->port == cutthrough.host.port
	 )
	{
	uschar * resp = NULL;

	/* Match!  Send the RCPT TO, set done from the response */
	done =
	     smtp_write_command(&ctctx, SCMD_FLUSH, "RCPT TO:<%.1000s>\r\n",
	      transport_rcpt_address(addr,
		 addr->transport->rcpt_include_affixes)) >= 0
	  && cutthrough_response(&cutthrough.cctx, '2', &resp,
	      CUTTHROUGH_DATA_TIMEOUT) == '2';

	/* This would go horribly wrong if a callout fail was ignored by ACL.
	We punt by abandoning cutthrough on a reject, like the
	first-rcpt does. */

	if (done)
	  {
	  address_item * na = store_get(sizeof(address_item), FALSE);
	  *na = cutthrough.addr;
	  cutthrough.addr = *addr;
	  cutthrough.addr.host_used = &cutthrough.host;
	  cutthrough.addr.next = na;

	  cutthrough.nrcpt++;
	  }
	else
	  {
	  cancel_cutthrough_connection(TRUE, US"recipient rejected");
	  if (!resp || errno == ETIMEDOUT)
	    {
	    HDEBUG(D_verify) debug_printf("SMTP timeout\n");
	    }
	  else if (errno == 0)
	    {
	    if (*resp == 0)
	      Ustrcpy(resp, US"connection dropped");

	    addr->message =
	      string_sprintf("response to \"%s\" was: %s",
		big_buffer, string_printing(resp));

	    addr->user_message =
	      string_sprintf("Callout verification failed:\n%s", resp);

	    /* Hard rejection ends the process */

	    if (resp[0] == '5')   /* Address rejected */
	      {
	      *yield = FAIL;
	      done = TRUE;
	      }
	    }
	  }
	}
      break;	/* host_list */
      }
if (!done)
  cancel_cutthrough_connection(TRUE, US"incompatible connection");
return done;
}


/*************************************************
*      Do callout verification for an address    *
*************************************************/

/* This function is called from verify_address() when the address has routed to
a host list, and a callout has been requested. Callouts are expensive; that is
why a cache is used to improve the efficiency.

Arguments:
  addr              the address that's been routed
  host_list         the list of hosts to try
  tf                the transport feedback block

  ifstring          "interface" option from transport, or NULL
  portstring        "port" option from transport, or NULL
  protocolstring    "protocol" option from transport, or NULL
  callout           the per-command callout timeout
  callout_overall   the overall callout timeout (if < 0 use 4*callout)
  callout_connect   the callout connection timeout (if < 0 use callout)
  options           the verification options - these bits are used:
                      vopt_is_recipient => this is a recipient address
                      vopt_callout_no_cache => don't use callout cache
                      vopt_callout_fullpm => if postmaster check, do full one
                      vopt_callout_random => do the "random" thing
                      vopt_callout_recipsender => use real sender for recipient
                      vopt_callout_recippmaster => use postmaster for recipient
		      vopt_callout_hold         => lazy close connection
  se_mailfrom         MAIL FROM address for sender verify; NULL => ""
  pm_mailfrom         if non-NULL, do the postmaster check with this sender

Returns:            OK/FAIL/DEFER
*/

static int
do_callout(address_item *addr, host_item *host_list, transport_feedback *tf,
  int callout, int callout_overall, int callout_connect, int options,
  uschar *se_mailfrom, uschar *pm_mailfrom)
{
int yield = OK;
int old_domain_cache_result = ccache_accept;
BOOL done = FALSE;
uschar *address_key;
uschar *from_address;
uschar *random_local_part = NULL;
const uschar *save_deliver_domain = deliver_domain;
uschar **failure_ptr = options & vopt_is_recipient
  ? &recipient_verify_failure : &sender_verify_failure;
dbdata_callout_cache new_domain_record;
dbdata_callout_cache_address new_address_record;
time_t callout_start_time;

new_domain_record.result = ccache_unknown;
new_domain_record.postmaster_result = ccache_unknown;
new_domain_record.random_result = ccache_unknown;

memset(&new_address_record, 0, sizeof(new_address_record));

/* For a recipient callout, the key used for the address cache record must
include the sender address if we are using the real sender in the callout,
because that may influence the result of the callout. */

if (options & vopt_is_recipient)
  if (options & vopt_callout_recipsender)
    {
    from_address = sender_address;
    address_key = string_sprintf("%s/<%s>", addr->address, sender_address);
    if (cutthrough.delivery) options |= vopt_callout_no_cache;
    }
  else if (options & vopt_callout_recippmaster)
    {
    from_address = string_sprintf("postmaster@%s", qualify_domain_sender);
    address_key = string_sprintf("%s/<postmaster@%s>", addr->address,
      qualify_domain_sender);
    }
  else
    {
    from_address = US"";
    address_key = addr->address;
    }

/* For a sender callout, we must adjust the key if the mailfrom address is not
empty. */

else
  {
  from_address = se_mailfrom ? se_mailfrom : US"";
  address_key = *from_address
    ? string_sprintf("%s/<%s>", addr->address, from_address) : addr->address;
  }

if (cached_callout_lookup(addr, address_key, from_address,
      &options, &pm_mailfrom, &yield, failure_ptr,
      &new_domain_record, &old_domain_cache_result))
  {
  cancel_cutthrough_connection(TRUE, US"cache-hit");
  goto END_CALLOUT;
  }

if (!addr->transport)
  {
  HDEBUG(D_verify) debug_printf("cannot callout via null transport\n");
  }
else if (Ustrcmp(addr->transport->driver_name, "smtp") != 0)
  log_write(0, LOG_MAIN|LOG_PANIC|LOG_CONFIG_FOR, "callout transport '%s': %s is non-smtp",
    addr->transport->name, addr->transport->driver_name);
else
  {
  smtp_transport_options_block *ob =
    (smtp_transport_options_block *)addr->transport->options_block;
  smtp_context * sx = NULL;

  /* The information wasn't available in the cache, so we have to do a real
  callout and save the result in the cache for next time, unless no_cache is set,
  or unless we have a previously cached negative random result. If we are to test
  with a random local part, ensure that such a local part is available. If not,
  log the fact, but carry on without randomising. */

  if (options & vopt_callout_random  &&  callout_random_local_part)
    if (!(random_local_part = expand_string(callout_random_local_part)))
      log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand "
        "callout_random_local_part: %s", expand_string_message);

  /* Compile regex' used by client-side smtp */

  smtp_deliver_init();

  /* Default the connect and overall callout timeouts if not set, and record the
  time we are starting so that we can enforce it. */

  if (callout_overall < 0) callout_overall = 4 * callout;
  if (callout_connect < 0) callout_connect = callout;
  callout_start_time = time(NULL);

  /* Before doing a real callout, if this is an SMTP connection, flush the SMTP
  output because a callout might take some time. When PIPELINING is active and
  there are many recipients, the total time for doing lots of callouts can add up
  and cause the client to time out. So in this case we forgo the PIPELINING
  optimization. */

  if (smtp_out && !f.disable_callout_flush) mac_smtp_fflush();

  clearflag(addr, af_verify_pmfail);  /* postmaster callout flag */
  clearflag(addr, af_verify_nsfail);  /* null sender callout flag */

/* cutthrough-multi: if a nonfirst rcpt has the same routing as the first,
and we are holding a cutthrough conn open, we can just append the rcpt to
that conn for verification purposes (and later delivery also).  Simplest
coding means skipping this whole loop and doing the append separately.  */

  /* Can we re-use an open cutthrough connection? */
  if (  cutthrough.cctx.sock >= 0
     && (options & (vopt_callout_recipsender | vopt_callout_recippmaster))
	== vopt_callout_recipsender
     && !random_local_part
     && !pm_mailfrom
     )
    done = cutthrough_multi(addr, host_list, tf, &yield);

  /* If we did not use a cached connection, make connections to the hosts
  and do real callouts. The list of hosts is passed in as an argument. */

  for (host_item * host = host_list; host && !done; host = host->next)
    {
    int host_af;
    int port = 25;
    uschar * interface = NULL;  /* Outgoing interface to use; NULL => any */

    if (!host->address)
      {
      DEBUG(D_verify) debug_printf("no IP address for host name %s: skipping\n",
        host->name);
      continue;
      }

    /* Check the overall callout timeout */

    if (time(NULL) - callout_start_time >= callout_overall)
      {
      HDEBUG(D_verify) debug_printf("overall timeout for callout exceeded\n");
      break;
      }

    /* Set IPv4 or IPv6 */

    host_af = Ustrchr(host->address, ':') ? AF_INET6 : AF_INET;

    /* Expand and interpret the interface and port strings. The latter will not
    be used if there is a host-specific port (e.g. from a manualroute router).
    This has to be delayed till now, because they may expand differently for
    different hosts. If there's a failure, log it, but carry on with the
    defaults. */

    deliver_host = host->name;
    deliver_host_address = host->address;
    deliver_host_port = host->port;
    deliver_domain = addr->domain;
    transport_name = addr->transport->name;

    if (  !smtp_get_interface(tf->interface, host_af, addr, &interface,
            US"callout")
       || !smtp_get_port(tf->port, addr, &port, US"callout")
       )
      log_write(0, LOG_MAIN|LOG_PANIC, "<%s>: %s", addr->address,
        addr->message);

    if (!sx) sx = store_get(sizeof(*sx), TRUE);	/* tainted buffers */
    memset(sx, 0, sizeof(*sx));

    sx->addrlist = sx->first_addr = addr;
    sx->conn_args.host = host;
    sx->conn_args.host_af = host_af,
    sx->port = port;
    sx->conn_args.interface = interface;
    sx->helo_data = tf->helo_data;
    sx->conn_args.tblock = addr->transport;
    sx->verify = TRUE;

tls_retry_connection:
    /* Set the address state so that errors are recorded in it */

    addr->transport_return = PENDING_DEFER;
    ob->connect_timeout = callout_connect;
    ob->command_timeout = callout;

    /* Get the channel set up ready for a message (MAIL FROM being the next
    SMTP command to send.  If we tried TLS but it failed, try again without
    if permitted */

    yield = smtp_setup_conn(sx, FALSE);
#ifndef DISABLE_TLS
    if (  yield == DEFER
       && addr->basic_errno == ERRNO_TLSFAILURE
       && ob->tls_tempfail_tryclear
       && verify_check_given_host(CUSS &ob->hosts_require_tls, host) != OK
       )
      {
      log_write(0, LOG_MAIN,
	"%s: callout unencrypted to %s [%s] (not in hosts_require_tls)",
	addr->message, host->name, host->address);
      addr->transport_return = PENDING_DEFER;
      yield = smtp_setup_conn(sx, TRUE);
      }
#endif
    if (yield != OK)
      {
      errno = addr->basic_errno;
      transport_name = NULL;
      deliver_host = deliver_host_address = NULL;
      deliver_domain = save_deliver_domain;

      /* Failure to accept HELO is cached; this blocks the whole domain for all
      senders. I/O errors and defer responses are not cached. */

      if (yield == FAIL && (errno == 0 || errno == ERRNO_SMTPCLOSED))
	{
	setflag(addr, af_verify_nsfail);
	new_domain_record.result = ccache_reject;
	done = TRUE;
	}
      else
	done = FALSE;
      goto no_conn;
      }

    /* If we needed to authenticate, smtp_setup_conn() did that.  Copy
    the AUTH info for logging */

    addr->authenticator = client_authenticator;
    addr->auth_id = client_authenticated_id;

    sx->from_addr = from_address;
    sx->first_addr = sx->sync_addr = addr;
    sx->ok = FALSE;			/*XXX these 3 last might not be needed for verify? */
    sx->send_rset = TRUE;
    sx->completed_addr = FALSE;

    new_domain_record.result = old_domain_cache_result == ccache_reject_mfnull
      ? ccache_reject_mfnull : ccache_accept;

    /* Do the random local part check first. Temporarily replace the recipient
    with the "random" value */

    if (random_local_part)
      {
      uschar * main_address = addr->address;
      const uschar * rcpt_domain = addr->domain;

#ifdef SUPPORT_I18N
      uschar * errstr = NULL;
      if (  testflag(addr, af_utf8_downcvt)
	 && (rcpt_domain = string_domain_utf8_to_alabel(rcpt_domain,
				    &errstr), errstr)
	 )
	{
	addr->message = errstr;
	errno = ERRNO_EXPANDFAIL;
	setflag(addr, af_verify_nsfail);
	done = FALSE;
	rcpt_domain = US"";  /*XXX errorhandling! */
	}
#endif

      /* This would be ok for 1st rcpt of a cutthrough (the case handled here;
      subsequents are done in cutthrough_multi()), but no way to
      handle a subsequent because of the RSET vaporising the MAIL FROM.
      So refuse to support any.  Most cutthrough use will not involve
      random_local_part, so no loss. */
      cancel_cutthrough_connection(TRUE, US"random-recipient");

      addr->address = string_sprintf("%s@%.1000s",
				    random_local_part, rcpt_domain);
      done = FALSE;

      /* If accepted, we aren't going to do any further tests below.
      Otherwise, cache a real negative response, and get back to the right
      state to send RCPT. Unless there's some problem such as a dropped
      connection, we expect to succeed, because the commands succeeded above.
      However, some servers drop the connection after responding to an
      invalid recipient, so on (any) error we drop and remake the connection.
      XXX We don't care about that for postmaster_full.  Should we?

      XXX could we add another flag to the context, and have the common
      code emit the RSET too?  Even pipelined after the RCPT...
      Then the main-verify call could use it if there's to be a subsequent
      postmaster-verify.
      The sync_responses() would need to be taught about it and we'd
      need another return code filtering out to here.

      Avoid using a SIZE option on the MAIL for all random-rcpt checks.
      */

      sx->avoid_option = OPTION_SIZE;

      /* Remember when we last did a random test */
      new_domain_record.random_stamp = time(NULL);

      if (smtp_write_mail_and_rcpt_cmds(sx, &yield) == 0)
	switch(addr->transport_return)
	  {
	  case PENDING_OK:	/* random was accepted, unfortunately */
	    new_domain_record.random_result = ccache_accept;
	    yield = OK;		/* Only usable verify result we can return */
	    done = TRUE;
	    *failure_ptr = US"random";
	    goto no_conn;
	  case FAIL:		/* rejected: the preferred result */
	    new_domain_record.random_result = ccache_reject;
	    sx->avoid_option = 0;

	    /* Between each check, issue RSET, because some servers accept only
	    one recipient after MAIL FROM:<>.
	    XXX We don't care about that for postmaster_full.  Should we? */

	    if ((done =
	      smtp_write_command(sx, SCMD_FLUSH, "RSET\r\n") >= 0 &&
	      smtp_read_response(sx, sx->buffer, sizeof(sx->buffer), '2', callout)))
	      break;

	    HDEBUG(D_acl|D_v)
	      debug_printf_indent("problem after random/rset/mfrom; reopen conn\n");
	    random_local_part = NULL;
#ifndef DISABLE_TLS
	    tls_close(sx->cctx.tls_ctx, TLS_SHUTDOWN_NOWAIT);
#endif
	    HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP(close)>>\n");
	    (void)close(sx->cctx.sock);
	    sx->cctx.sock = -1;
#ifndef DISABLE_EVENT
	    (void) event_raise(addr->transport->event_action,
			      US"tcp:close", NULL);
#endif
	    addr->address = main_address;
	    addr->transport_return = PENDING_DEFER;
	    sx->first_addr = sx->sync_addr = addr;
	    sx->ok = FALSE;
	    sx->send_rset = TRUE;
	    sx->completed_addr = FALSE;
	    goto tls_retry_connection;
	  case DEFER:		/* 4xx response to random */
	    break;		/* Just to be clear. ccache_unknown, !done. */
	  }

      /* Re-setup for main verify, or for the error message when failing */
      addr->address = main_address;
      addr->transport_return = PENDING_DEFER;
      sx->first_addr = sx->sync_addr = addr;
      sx->ok = FALSE;
      sx->send_rset = TRUE;
      sx->completed_addr = FALSE;
      }
    else
      done = TRUE;

    /* Main verify.  For rcpt-verify use SIZE if we know it and we're not cacheing;
    for sndr-verify never use it. */

    if (done)
      {
      if (!(options & vopt_is_recipient  &&  options & vopt_callout_no_cache))
	sx->avoid_option = OPTION_SIZE;

      done = FALSE;
      switch(smtp_write_mail_and_rcpt_cmds(sx, &yield))
	{
	case 0:  switch(addr->transport_return)	/* ok so far */
		    {
		    case PENDING_OK:  done = TRUE;
				      new_address_record.result = ccache_accept;
				      break;
		    case FAIL:	      done = TRUE;
				      yield = FAIL;
				      *failure_ptr = US"recipient";
				      new_address_record.result = ccache_reject;
				      break;
		    default:	      break;
		    }
		  break;

	case -1:				/* MAIL response error */
		  *failure_ptr = US"mail";
		  if (errno == 0 && sx->buffer[0] == '5')
		    {
		    setflag(addr, af_verify_nsfail);
		    if (from_address[0] == 0)
		      new_domain_record.result = ccache_reject_mfnull;
		    }
		  break;
						/* non-MAIL read i/o error */
						/* non-MAIL response timeout */
						/* internal error; channel still usable */
	default:  break;			/* transmit failed */
	}
      }

    addr->auth_sndr = client_authenticated_sender;

    deliver_host = deliver_host_address = NULL;
    deliver_domain = save_deliver_domain;

    /* Do postmaster check if requested; if a full check is required, we
    check for RCPT TO:<postmaster> (no domain) in accordance with RFC 821. */

    if (done && pm_mailfrom)
      {
      /* Could possibly shift before main verify, just above, and be ok
      for cutthrough.  But no way to handle a subsequent rcpt, so just
      refuse any */
      cancel_cutthrough_connection(TRUE, US"postmaster verify");
      HDEBUG(D_acl|D_v) debug_printf_indent("Cutthrough cancelled by presence of postmaster verify\n");

      done = smtp_write_command(sx, SCMD_FLUSH, "RSET\r\n") >= 0
          && smtp_read_response(sx, sx->buffer, sizeof(sx->buffer), '2', callout);

      if (done)
	{
	uschar * main_address = addr->address;

	/*XXX oops, affixes */
	addr->address = string_sprintf("postmaster@%.1000s", addr->domain);
	addr->transport_return = PENDING_DEFER;

	sx->from_addr = pm_mailfrom;
	sx->first_addr = sx->sync_addr = addr;
	sx->ok = FALSE;
	sx->send_rset = TRUE;
	sx->completed_addr = FALSE;
	sx->avoid_option = OPTION_SIZE;

	if(  smtp_write_mail_and_rcpt_cmds(sx, &yield) == 0
	  && addr->transport_return == PENDING_OK
	  )
	  done = TRUE;
	else
	  done = (options & vopt_callout_fullpm) != 0
	      && smtp_write_command(sx, SCMD_FLUSH,
			    "RCPT TO:<postmaster>\r\n") >= 0
	      && smtp_read_response(sx, sx->buffer,
			    sizeof(sx->buffer), '2', callout);

	/* Sort out the cache record */

	new_domain_record.postmaster_stamp = time(NULL);

	if (done)
	  new_domain_record.postmaster_result = ccache_accept;
	else if (errno == 0 && sx->buffer[0] == '5')
	  {
	  *failure_ptr = US"postmaster";
	  setflag(addr, af_verify_pmfail);
	  new_domain_record.postmaster_result = ccache_reject;
	  }

	addr->address = main_address;
	}
      }
    /* For any failure of the main check, other than a negative response, we just
    close the connection and carry on. We can identify a negative response by the
    fact that errno is zero. For I/O errors it will be non-zero

    Set up different error texts for logging and for sending back to the caller
    as an SMTP response. Log in all cases, using a one-line format. For sender
    callouts, give a full response to the caller, but for recipient callouts,
    don't give the IP address because this may be an internal host whose identity
    is not to be widely broadcast. */

no_conn:
    switch(errno)
      {
      case ETIMEDOUT:
	HDEBUG(D_verify) debug_printf("SMTP timeout\n");
	sx->send_quit = FALSE;
	break;

#ifdef SUPPORT_I18N
      case ERRNO_UTF8_FWD:
	{
	extern int acl_where;	/* src/acl.c */
	errno = 0;
	addr->message = US"response to \"EHLO\" did not include SMTPUTF8";
	addr->user_message = acl_where == ACL_WHERE_RCPT
	  ? US"533 no support for internationalised mailbox name"
	  : US"550 mailbox unavailable";
	yield = FAIL;
	done = TRUE;
	}
	break;
#endif
      case ECONNREFUSED:
	sx->send_quit = FALSE;
	break;

      case 0:
	if (*sx->buffer == 0) Ustrcpy(sx->buffer, US"connection dropped");

	/*XXX test here is ugly; seem to have a split of responsibility for
	building this message.  Need to rationalise.  Where is it done
	before here, and when not?
	Not == 5xx resp to MAIL on main-verify
	*/
	if (!addr->message) addr->message =
	  string_sprintf("response to \"%s\" was: %s",
			  big_buffer, string_printing(sx->buffer));

	/* RFC 5321 section 4.2: the text portion of the response may have only
	HT, SP, Printable US-ASCII.  Deal with awkward chars by cutting the
	received message off before passing it onward.  Newlines are ok; they
	just become a multiline response (but wrapped in the error code we
	produce). */

	for (uschar * s = sx->buffer;
	     *s && s < sx->buffer + sizeof(sx->buffer);
	     s++)
	  {
	  uschar c = *s;
	  if (c != '\t' && c != '\n' && (c < ' ' || c > '~'))
	    {
	    if (s - sx->buffer < sizeof(sx->buffer) - 12)
	      memcpy(s, "(truncated)", 12);
	    else
	      *s = '\0';
	    break;
	    }
	  }
	addr->user_message = options & vopt_is_recipient
	  ? string_sprintf("Callout verification failed:\n%s", sx->buffer)
	  : string_sprintf("Called:   %s\nSent:     %s\nResponse: %s",
	    host->address, big_buffer, sx->buffer);

	/* Hard rejection ends the process */

	if (sx->buffer[0] == '5')   /* Address rejected */
	  {
	  yield = FAIL;
	  done = TRUE;
	  }
	break;
      }

    /* End the SMTP conversation and close the connection. */

    /* Cutthrough - on a successful connect and recipient-verify with
    use-sender and we are 1st rcpt and have no cutthrough conn so far
    here is where we want to leave the conn open.  Ditto for a lazy-close
    verify. */

    if (cutthrough.delivery)
      {
      if (addr->transport->filter_command)
        {
        cutthrough.delivery= FALSE;
        HDEBUG(D_acl|D_v) debug_printf("Cutthrough cancelled by presence of transport filter\n");
        }
#ifndef DISABLE_DKIM
      if (ob->dkim.dkim_domain)
        {
        cutthrough.delivery= FALSE;
        HDEBUG(D_acl|D_v) debug_printf("Cutthrough cancelled by presence of DKIM signing\n");
        }
#endif
#ifdef EXPERIMENTAL_ARC
      if (ob->arc_sign)
        {
        cutthrough.delivery= FALSE;
        HDEBUG(D_acl|D_v) debug_printf("Cutthrough cancelled by presence of ARC signing\n");
        }
#endif
      }

    if (  (cutthrough.delivery || options & vopt_callout_hold)
       && rcpt_count == 1
       && done
       && yield == OK
       &&    (options & (vopt_callout_recipsender|vopt_callout_recippmaster|vopt_success_on_redirect))
	   == vopt_callout_recipsender
       && !random_local_part
       && !pm_mailfrom
       && cutthrough.cctx.sock < 0
       && !sx->lmtp
       )
      {
      HDEBUG(D_acl|D_v) debug_printf_indent("holding verify callout open for %s\n",
	cutthrough.delivery
	? "cutthrough delivery" : "potential further verifies and delivery");

      cutthrough.callout_hold_only = !cutthrough.delivery;
      cutthrough.is_tls =	tls_out.active.sock >= 0;
      /* We assume no buffer in use in the outblock */
      cutthrough.cctx =		sx->cctx;
      cutthrough.nrcpt =	1;
      cutthrough.transport =	addr->transport->name;
      cutthrough.interface =	interface;
      cutthrough.snd_port =	sending_port;
      cutthrough.peer_options =	smtp_peer_options;
      cutthrough.host =		*host;
	{
	int oldpool = store_pool;
	store_pool = POOL_PERM;
	cutthrough.snd_ip = string_copy(sending_ip_address);
	cutthrough.host.name = string_copy(host->name);
	cutthrough.host.address = string_copy(host->address);
	store_pool = oldpool;
	}

      /* Save the address_item and parent chain for later logging */
      cutthrough.addr =		*addr;
      cutthrough.addr.next =	NULL;
      cutthrough.addr.host_used = &cutthrough.host;
      for (address_item * caddr = &cutthrough.addr, * parent = addr->parent;
	   parent;
	   caddr = caddr->parent, parent = parent->parent)
        *(caddr->parent = store_get(sizeof(address_item), FALSE)) = *parent;

      ctctx.outblock.buffer = ctbuffer;
      ctctx.outblock.buffersize = sizeof(ctbuffer);
      ctctx.outblock.ptr = ctbuffer;
      /* ctctx.outblock.cmd_count = 0; ctctx.outblock.authenticating = FALSE; */
      ctctx.outblock.cctx = &cutthrough.cctx;
      }
    else
      {
      /* Ensure no cutthrough on multiple verifies that were incompatible */
      if (options & vopt_callout_recipsender)
        cancel_cutthrough_connection(TRUE, US"not usable for cutthrough");
      if (sx->send_quit)
	if (smtp_write_command(sx, SCMD_FLUSH, "QUIT\r\n") != -1)
	  /* Wait a short time for response, and discard it */
	  smtp_read_response(sx, sx->buffer, sizeof(sx->buffer), '2', 1);

      if (sx->cctx.sock >= 0)
	{
#ifndef DISABLE_TLS
	if (sx->cctx.tls_ctx)
	  {
	  tls_close(sx->cctx.tls_ctx, TLS_SHUTDOWN_NOWAIT);
	  sx->cctx.tls_ctx = NULL;
	  }
#endif
	HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP(close)>>\n");
	(void)close(sx->cctx.sock);
	sx->cctx.sock = -1;
#ifndef DISABLE_EVENT
	(void) event_raise(addr->transport->event_action, US"tcp:close", NULL);
#endif
	}
      }

    if (!done || yield != OK)
      addr->message = string_sprintf("%s [%s] : %s", host->name, host->address,
				    addr->message);
    }    /* Loop through all hosts, while !done */
  }

/* If we get here with done == TRUE, a successful callout happened, and yield
will be set OK or FAIL according to the response to the RCPT command.
Otherwise, we looped through the hosts but couldn't complete the business.
However, there may be domain-specific information to cache in both cases. */

if (!(options & vopt_callout_no_cache))
  cache_callout_write(&new_domain_record, addr->domain,
    done, &new_address_record, address_key);

/* Failure to connect to any host, or any response other than 2xx or 5xx is a
temporary error. If there was only one host, and a response was received, leave
it alone if supplying details. Otherwise, give a generic response. */

if (!done)
  {
  uschar * dullmsg = string_sprintf("Could not complete %s verify callout",
    options & vopt_is_recipient ? "recipient" : "sender");
  yield = DEFER;

  addr->message = host_list->next || !addr->message
    ? dullmsg : string_sprintf("%s: %s", dullmsg, addr->message);

  addr->user_message = smtp_return_error_details
    ? string_sprintf("%s for <%s>.\n"
      "The mail server(s) for the domain may be temporarily unreachable, or\n"
      "they may be permanently unreachable from this server. In the latter case,\n%s",
      dullmsg, addr->address,
      options & vopt_is_recipient
	? "the address will never be accepted."
        : "you need to change the address or create an MX record for its domain\n"
	  "if it is supposed to be generally accessible from the Internet.\n"
	  "Talk to your mail administrator for details.")
    : dullmsg;

  /* Force a specific error code */

  addr->basic_errno = ERRNO_CALLOUTDEFER;
  }

/* Come here from within the cache-reading code on fast-track exit. */

END_CALLOUT:
tls_modify_variables(&tls_in);	/* return variables to inbound values */
return yield;
}



/* Called after recipient-acl to get a cutthrough connection open when
   one was requested and a recipient-verify wasn't subsequently done.
*/
int
open_cutthrough_connection(address_item * addr)
{
address_item addr2;
int rc;

/* Use a recipient-verify-callout to set up the cutthrough connection. */
/* We must use a copy of the address for verification, because it might
get rewritten. */

addr2 = *addr;
HDEBUG(D_acl) debug_printf_indent("----------- %s cutthrough setup ------------\n",
  rcpt_count > 1 ? "more" : "start");
rc = verify_address(&addr2, NULL,
	vopt_is_recipient | vopt_callout_recipsender | vopt_callout_no_cache,
	CUTTHROUGH_CMD_TIMEOUT, -1, -1,
	NULL, NULL, NULL);
addr->message = addr2.message;
addr->user_message = addr2.user_message;
HDEBUG(D_acl) debug_printf_indent("----------- end cutthrough setup ------------\n");
return rc;
}



/* Send given number of bytes from the buffer */
static BOOL
cutthrough_send(int n)
{
if(cutthrough.cctx.sock < 0)
  return TRUE;

if(
#ifndef DISABLE_TLS
   cutthrough.is_tls
   ? tls_write(cutthrough.cctx.tls_ctx, ctctx.outblock.buffer, n, FALSE)
   :
#endif
     send(cutthrough.cctx.sock, ctctx.outblock.buffer, n, 0) > 0
  )
{
  transport_count += n;
  ctctx.outblock.ptr= ctctx.outblock.buffer;
  return TRUE;
}

HDEBUG(D_transport|D_acl) debug_printf_indent("cutthrough_send failed: %s\n", strerror(errno));
return FALSE;
}



static BOOL
_cutthrough_puts(uschar * cp, int n)
{
while(n--)
 {
 if(ctctx.outblock.ptr >= ctctx.outblock.buffer+ctctx.outblock.buffersize)
   if(!cutthrough_send(ctctx.outblock.buffersize))
     return FALSE;

 *ctctx.outblock.ptr++ = *cp++;
 }
return TRUE;
}

/* Buffered output of counted data block.   Return boolean success */
static BOOL
cutthrough_puts(uschar * cp, int n)
{
if (cutthrough.cctx.sock < 0) return TRUE;
if (_cutthrough_puts(cp, n))  return TRUE;
cancel_cutthrough_connection(TRUE, US"transmit failed");
return FALSE;
}

void
cutthrough_data_puts(uschar * cp, int n)
{
if (cutthrough.delivery) (void) cutthrough_puts(cp, n);
return;
}


static BOOL
_cutthrough_flush_send(void)
{
int n = ctctx.outblock.ptr - ctctx.outblock.buffer;

if(n>0)
  if(!cutthrough_send(n))
    return FALSE;
return TRUE;
}


/* Send out any bufferred output.  Return boolean success. */
BOOL
cutthrough_flush_send(void)
{
if (_cutthrough_flush_send()) return TRUE;
cancel_cutthrough_connection(TRUE, US"transmit failed");
return FALSE;
}


static BOOL
cutthrough_put_nl(void)
{
return cutthrough_puts(US"\r\n", 2);
}


void
cutthrough_data_put_nl(void)
{
cutthrough_data_puts(US"\r\n", 2);
}


/* Get and check response from cutthrough target */
static uschar
cutthrough_response(client_conn_ctx * cctx, char expect, uschar ** copy, int timeout)
{
smtp_context sx = {0};
uschar inbuffer[4096];
uschar responsebuffer[4096];

sx.inblock.buffer = inbuffer;
sx.inblock.buffersize = sizeof(inbuffer);
sx.inblock.ptr = inbuffer;
sx.inblock.ptrend = inbuffer;
sx.inblock.cctx = cctx;
if(!smtp_read_response(&sx, responsebuffer, sizeof(responsebuffer), expect, timeout))
  cancel_cutthrough_connection(TRUE, US"target timeout on read");

if(copy)
  {
  uschar * cp;
  *copy = cp = string_copy(responsebuffer);
  /* Trim the trailing end of line */
  cp += Ustrlen(responsebuffer);
  if(cp > *copy  &&  cp[-1] == '\n') *--cp = '\0';
  if(cp > *copy  &&  cp[-1] == '\r') *--cp = '\0';
  }

return responsebuffer[0];
}


/* Negotiate dataphase with the cutthrough target, returning success boolean */
BOOL
cutthrough_predata(void)
{
if(cutthrough.cctx.sock < 0 || cutthrough.callout_hold_only)
  return FALSE;

HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP>> DATA\n");
cutthrough_puts(US"DATA\r\n", 6);
cutthrough_flush_send();

/* Assume nothing buffered.  If it was it gets ignored. */
return cutthrough_response(&cutthrough.cctx, '3', NULL, CUTTHROUGH_DATA_TIMEOUT) == '3';
}


/* tctx arg only to match write_chunk() */
static BOOL
cutthrough_write_chunk(transport_ctx * tctx, uschar * s, int len)
{
uschar * s2;
while(s && (s2 = Ustrchr(s, '\n')))
 {
 if(!cutthrough_puts(s, s2-s) || !cutthrough_put_nl())
  return FALSE;
 s = s2+1;
 }
return TRUE;
}


/* Buffered send of headers.  Return success boolean. */
/* Expands newlines to wire format (CR,NL).           */
/* Also sends header-terminating blank line.          */
BOOL
cutthrough_headers_send(void)
{
transport_ctx tctx;

if(cutthrough.cctx.sock < 0 || cutthrough.callout_hold_only)
  return FALSE;

/* We share a routine with the mainline transport to handle header add/remove/rewrites,
   but having a separate buffered-output function (for now)
*/
HDEBUG(D_acl) debug_printf_indent("----------- start cutthrough headers send -----------\n");

tctx.u.fd = cutthrough.cctx.sock;
tctx.tblock = cutthrough.addr.transport;
tctx.addr = &cutthrough.addr;
tctx.check_string = US".";
tctx.escape_string = US"..";
/*XXX check under spool_files_wireformat.  Might be irrelevant */
tctx.options = topt_use_crlf;

if (!transport_headers_send(&tctx, &cutthrough_write_chunk))
  return FALSE;

HDEBUG(D_acl) debug_printf_indent("----------- done cutthrough headers send ------------\n");
return TRUE;
}


static void
close_cutthrough_connection(const uschar * why)
{
int fd = cutthrough.cctx.sock;
if(fd >= 0)
  {
  /* We could be sending this after a bunch of data, but that is ok as
     the only way to cancel the transfer in dataphase is to drop the tcp
     conn before the final dot.
  */
  client_conn_ctx tmp_ctx = cutthrough.cctx;
  ctctx.outblock.ptr = ctbuffer;
  HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP>> QUIT\n");
  _cutthrough_puts(US"QUIT\r\n", 6);	/* avoid recursion */
  _cutthrough_flush_send();
  cutthrough.cctx.sock = -1;		/* avoid recursion via read timeout */
  cutthrough.nrcpt = 0;			/* permit re-cutthrough on subsequent message */

  /* Wait a short time for response, and discard it */
  cutthrough_response(&tmp_ctx, '2', NULL, 1);

#ifndef DISABLE_TLS
  if (cutthrough.is_tls)
    {
    tls_close(cutthrough.cctx.tls_ctx, TLS_SHUTDOWN_NOWAIT);
    cutthrough.cctx.tls_ctx = NULL;
    cutthrough.is_tls = FALSE;
    }
#endif
  HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP(close)>>\n");
  (void)close(fd);
  HDEBUG(D_acl) debug_printf_indent("----------- cutthrough shutdown (%s) ------------\n", why);
  }
ctctx.outblock.ptr = ctbuffer;
}

void
cancel_cutthrough_connection(BOOL close_noncutthrough_verifies, const uschar * why)
{
if (cutthrough.delivery || close_noncutthrough_verifies)
  close_cutthrough_connection(why);
cutthrough.delivery = cutthrough.callout_hold_only = FALSE;
}


void
release_cutthrough_connection(const uschar * why)
{
if (cutthrough.cctx.sock < 0) return;
HDEBUG(D_acl) debug_printf_indent("release cutthrough conn: %s\n", why);
cutthrough.cctx.sock = -1;
cutthrough.cctx.tls_ctx = NULL;
cutthrough.delivery = cutthrough.callout_hold_only = FALSE;
}




/* Have senders final-dot.  Send one to cutthrough target, and grab the response.
   Log an OK response as a transmission.
   Close the connection.
   Return smtp response-class digit.
*/
uschar *
cutthrough_finaldot(void)
{
uschar res;
HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP>> .\n");

/* Assume data finshed with new-line */
if(  !cutthrough_puts(US".", 1)
  || !cutthrough_put_nl()
  || !cutthrough_flush_send()
  )
  return cutthrough.addr.message;

res = cutthrough_response(&cutthrough.cctx, '2', &cutthrough.addr.message,
	CUTTHROUGH_DATA_TIMEOUT);
for (address_item * addr = &cutthrough.addr; addr; addr = addr->next)
  {
  addr->message = cutthrough.addr.message;
  switch(res)
    {
    case '2':
      delivery_log(LOG_MAIN, addr, (int)'>', NULL);
      close_cutthrough_connection(US"delivered");
      break;

    case '4':
      delivery_log(LOG_MAIN, addr, 0,
	US"tmp-reject from cutthrough after DATA:");
      break;

    case '5':
      delivery_log(LOG_MAIN|LOG_REJECT, addr, 0,
	US"rejected after DATA:");
      break;

    default:
      break;
    }
  }
return cutthrough.addr.message;
}



/*************************************************
*           Copy error to toplevel address       *
*************************************************/

/* This function is used when a verify fails or defers, to ensure that the
failure or defer information is in the original toplevel address. This applies
when an address is redirected to a single new address, and the failure or
deferral happens to the child address.

Arguments:
  vaddr       the verify address item
  addr        the final address item
  yield       FAIL or DEFER

Returns:      the value of YIELD
*/

static int
copy_error(address_item *vaddr, address_item *addr, int yield)
{
if (addr != vaddr)
  {
  vaddr->message = addr->message;
  vaddr->user_message = addr->user_message;
  vaddr->basic_errno = addr->basic_errno;
  vaddr->more_errno = addr->more_errno;
  vaddr->prop.address_data = addr->prop.address_data;
  vaddr->prop.variables = NULL;
  tree_dup((tree_node **)&vaddr->prop.variables, addr->prop.variables);
  copyflag(vaddr, addr, af_pass_message);
  }
return yield;
}




/**************************************************
* printf that automatically handles TLS if needed *
***************************************************/

/* This function is used by verify_address() as a substitute for all fprintf()
calls; a direct fprintf() will not produce output in a TLS SMTP session, such
as a response to an EXPN command.  smtp_in.c makes smtp_printf available but
that assumes that we always use the smtp_out FILE* when not using TLS or the
ssl buffer when we are.  Instead we take a FILE* parameter and check to see if
that is smtp_out; if so, smtp_printf() with TLS support, otherwise regular
fprintf().

Arguments:
  f           the candidate FILE* to write to
  format      format string
  ...         optional arguments

Returns:
              nothing
*/

static void PRINTF_FUNCTION(2,3)
respond_printf(FILE *f, const char *format, ...)
{
va_list ap;

va_start(ap, format);
if (smtp_out && (f == smtp_out))
  smtp_vprintf(format, FALSE, ap);
else
  vfprintf(f, format, ap);
va_end(ap);
}



/*************************************************
*            Verify an email address             *
*************************************************/

/* This function is used both for verification (-bv and at other times) and
address testing (-bt), which is indicated by address_test_mode being set.

Arguments:
  vaddr            contains the address to verify; the next field in this block
                     must be NULL
  f                if not NULL, write the result to this file
  options          various option bits:
                     vopt_fake_sender => this sender verify is not for the real
                       sender (it was verify=sender=xxxx or an address from a
                       header line) - rewriting must not change sender_address
                     vopt_is_recipient => this is a recipient address, otherwise
                       it's a sender address - this affects qualification and
                       rewriting and messages from callouts
                     vopt_qualify => qualify an unqualified address; else error
                     vopt_expn => called from SMTP EXPN command
                     vopt_success_on_redirect => when a new address is generated
                       the verification instantly succeeds

                     These ones are used by do_callout() -- the options variable
                       is passed to it.

                     vopt_callout_fullpm => if postmaster check, do full one
                     vopt_callout_no_cache => don't use callout cache
                     vopt_callout_random => do the "random" thing
                     vopt_callout_recipsender => use real sender for recipient
                     vopt_callout_recippmaster => use postmaster for recipient

  callout          if > 0, specifies that callout is required, and gives timeout
                     for individual commands
  callout_overall  if > 0, gives overall timeout for the callout function;
                   if < 0, a default is used (see do_callout())
  callout_connect  the connection timeout for callouts
  se_mailfrom      when callout is requested to verify a sender, use this
                     in MAIL FROM; NULL => ""
  pm_mailfrom      when callout is requested, if non-NULL, do the postmaster
                     thing and use this as the sender address (may be "")

  routed           if not NULL, set TRUE if routing succeeded, so we can
                     distinguish between routing failed and callout failed

Returns:           OK      address verified
                   FAIL    address failed to verify
                   DEFER   can't tell at present
*/

int
verify_address(address_item * vaddr, FILE * fp, int options, int callout,
  int callout_overall, int callout_connect, uschar * se_mailfrom,
  uschar *pm_mailfrom, BOOL *routed)
{
BOOL allok = TRUE;
BOOL full_info = fp ? debug_selector != 0 : FALSE;
BOOL expn         = (options & vopt_expn) != 0;
BOOL success_on_redirect = (options & vopt_success_on_redirect) != 0;
int i;
int yield = OK;
int verify_type = expn? v_expn :
   f.address_test_mode? v_none :
          options & vopt_is_recipient? v_recipient : v_sender;
address_item *addr_list;
address_item *addr_new = NULL;
address_item *addr_remote = NULL;
address_item *addr_local = NULL;
address_item *addr_succeed = NULL;
uschar **failure_ptr = options & vopt_is_recipient
  ? &recipient_verify_failure : &sender_verify_failure;
uschar *ko_prefix, *cr;
uschar *address = vaddr->address;
uschar *save_sender;
uschar null_sender[] = { 0 };             /* Ensure writeable memory */

/* Clear, just in case */

*failure_ptr = NULL;

/* Set up a prefix and suffix for error message which allow us to use the same
output statements both in EXPN mode (where an SMTP response is needed) and when
debugging with an output file. */

if (expn)
  {
  ko_prefix = US"553 ";
  cr = US"\r";
  }
else ko_prefix = cr = US"";

/* Add qualify domain if permitted; otherwise an unqualified address fails. */

if (parse_find_at(address) == NULL)
  {
  if (!(options & vopt_qualify))
    {
    if (fp)
      respond_printf(fp, "%sA domain is required for \"%s\"%s\n",
        ko_prefix, address, cr);
    *failure_ptr = US"qualify";
    return FAIL;
    }
  /* deconst ok as address was not const */
  address = US rewrite_address_qualify(address, options & vopt_is_recipient);
  }

DEBUG(D_verify)
  {
  debug_printf(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
  debug_printf("%s %s\n", f.address_test_mode? "Testing" : "Verifying", address);
  }

/* Rewrite and report on it. Clear the domain and local part caches - these
may have been set by domains and local part tests during an ACL. */

if (global_rewrite_rules)
  {
  uschar *old = address;
  /* deconst ok as address was not const */
  address = US rewrite_address(address, options & vopt_is_recipient, FALSE,
    global_rewrite_rules, rewrite_existflags);
  if (address != old)
    {
    for (int i = 0; i < (MAX_NAMED_LIST * 2)/32; i++) vaddr->localpart_cache[i] = 0;
    for (int i = 0; i < (MAX_NAMED_LIST * 2)/32; i++) vaddr->domain_cache[i] = 0;
    if (fp && !expn) fprintf(fp, "Address rewritten as: %s\n", address);
    }
  }

/* If this is the real sender address, we must update sender_address at
this point, because it may be referred to in the routers. */

if (!(options & (vopt_fake_sender|vopt_is_recipient)))
  sender_address = address;

/* If the address was rewritten to <> no verification can be done, and we have
to return OK. This rewriting is permitted only for sender addresses; for other
addresses, such rewriting fails. */

if (!address[0]) return OK;

/* Flip the legacy TLS-related variables over to the outbound set in case
they're used in the context of a transport used by verification. Reset them
at exit from this routine (so no returns allowed from here on). */

tls_modify_variables(&tls_out);

/* Save a copy of the sender address for re-instating if we change it to <>
while verifying a sender address (a nice bit of self-reference there). */

save_sender = sender_address;

/* Observability variable for router/transport use */

verify_mode = options & vopt_is_recipient ? US"R" : US"S";

/* Update the address structure with the possibly qualified and rewritten
address. Set it up as the starting address on the chain of new addresses. */

vaddr->address = address;
addr_new = vaddr;

/* We need a loop, because an address can generate new addresses. We must also
cope with generated pipes and files at the top level. (See also the code and
comment in deliver.c.) However, it is usually the case that the router for
user's .forward files has its verify flag turned off.

If an address generates more than one child, the loop is used only when
full_info is set, and this can only be set locally. Remote enquiries just get
information about the top level address, not anything that it generated. */

while (addr_new)
  {
  int rc;
  address_item *addr = addr_new;

  addr_new = addr->next;
  addr->next = NULL;

  DEBUG(D_verify)
    {
    debug_printf(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
    debug_printf("Considering %s\n", addr->address);
    }

  /* Handle generated pipe, file or reply addresses. We don't get these
  when handling EXPN, as it does only one level of expansion. */

  if (testflag(addr, af_pfr))
    {
    allok = FALSE;
    if (fp)
      {
      BOOL allow;

      if (addr->address[0] == '>')
        {
        allow = testflag(addr, af_allow_reply);
        fprintf(fp, "%s -> mail %s", addr->parent->address, addr->address + 1);
        }
      else
        {
        allow = addr->address[0] == '|'
          ? testflag(addr, af_allow_pipe) : testflag(addr, af_allow_file);
        fprintf(fp, "%s -> %s", addr->parent->address, addr->address);
        }

      if (addr->basic_errno == ERRNO_BADTRANSPORT)
        fprintf(fp, "\n*** Error in setting up pipe, file, or autoreply:\n"
          "%s\n", addr->message);
      else if (allow)
        fprintf(fp, "\n  transport = %s\n", addr->transport->name);
      else
        fprintf(fp, " *** forbidden ***\n");
      }
    continue;
    }

  /* Just in case some router parameter refers to it. */

  return_path = addr->prop.errors_address
    ? addr->prop.errors_address : sender_address;

  /* Split the address into domain and local part, handling the %-hack if
  necessary, and then route it. While routing a sender address, set
  $sender_address to <> because that is what it will be if we were trying to
  send a bounce to the sender. */

  if (routed) *routed = FALSE;
  if ((rc = deliver_split_address(addr)) == OK)
    {
    if (!(options & vopt_is_recipient)) sender_address = null_sender;
    rc = route_address(addr, &addr_local, &addr_remote, &addr_new,
      &addr_succeed, verify_type);
    sender_address = save_sender;     /* Put back the real sender */
    }

  /* If routing an address succeeded, set the flag that remembers, for use when
  an ACL cached a sender verify (in case a callout fails). Then if routing set
  up a list of hosts or the transport has a host list, and the callout option
  is set, and we aren't in a host checking run, do the callout verification,
  and set another flag that notes that a callout happened. */

  if (rc == OK)
    {
    if (routed) *routed = TRUE;
    if (callout > 0)
      {
      transport_instance * tp;
      host_item * host_list = addr->host_list;

      /* Make up some data for use in the case where there is no remote
      transport. */

      transport_feedback tf = {
        .interface =		NULL,                       /* interface (=> any) */
        .port =			US"smtp",
        .protocol =		US"smtp",
        .hosts =		NULL,
        .helo_data =		US"$smtp_active_hostname",
        .hosts_override =	FALSE,
        .hosts_randomize =	FALSE,
        .gethostbyname =	FALSE,
        .qualify_single =	TRUE,
        .search_parents =	FALSE
        };

      /* If verification yielded a remote transport, we want to use that
      transport's options, so as to mimic what would happen if we were really
      sending a message to this address. */

      if ((tp = addr->transport) && !tp->info->local)
        {
        (void)(tp->setup)(tp, addr, &tf, 0, 0, NULL);

        /* If the transport has hosts and the router does not, or if the
        transport is configured to override the router's hosts, we must build a
        host list of the transport's hosts, and find the IP addresses */

        if (tf.hosts && (!host_list || tf.hosts_override))
          {
          uschar *s;
          const uschar *save_deliver_domain = deliver_domain;
          uschar *save_deliver_localpart = deliver_localpart;

          host_list = NULL;    /* Ignore the router's hosts */

          deliver_domain = addr->domain;
          deliver_localpart = addr->local_part;
          s = expand_string(tf.hosts);
          deliver_domain = save_deliver_domain;
          deliver_localpart = save_deliver_localpart;

          if (!s)
            {
            log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand list of hosts "
              "\"%s\" in %s transport for callout: %s", tf.hosts,
              tp->name, expand_string_message);
            }
          else
            {
            int flags;
            host_build_hostlist(&host_list, s, tf.hosts_randomize);

            /* Just ignore failures to find a host address. If we don't manage
            to find any addresses, the callout will defer. Note that more than
            one address may be found for a single host, which will result in
            additional host items being inserted into the chain. Hence we must
            save the next host first. */

            flags = HOST_FIND_BY_A | HOST_FIND_BY_AAAA;
            if (tf.qualify_single) flags |= HOST_FIND_QUALIFY_SINGLE;
            if (tf.search_parents) flags |= HOST_FIND_SEARCH_PARENTS;

            for (host_item * host = host_list, * nexthost; host; host = nexthost)
              {
              nexthost = host->next;
              if (tf.gethostbyname ||
                  string_is_ip_address(host->name, NULL) != 0)
                (void)host_find_byname(host, NULL, flags, NULL, TRUE);
              else
		{
		const dnssec_domains * dsp = NULL;
		if (Ustrcmp(tp->driver_name, "smtp") == 0)
		  {
		  smtp_transport_options_block * ob =
		      (smtp_transport_options_block *) tp->options_block;
		  dsp = &ob->dnssec;
		  }

                (void) host_find_bydns(host, NULL, flags, NULL, NULL, NULL,
		  dsp, NULL, NULL);
		}
              }
            }
          }
        }

      /* Can only do a callout if we have at least one host! If the callout
      fails, it will have set ${sender,recipient}_verify_failure. */

      if (host_list)
        {
        HDEBUG(D_verify) debug_printf("Attempting full verification using callout\n");
        if (host_checking && !f.host_checking_callout)
          {
          HDEBUG(D_verify)
            debug_printf("... callout omitted by default when host testing\n"
              "(Use -bhc if you want the callouts to happen.)\n");
          }
        else
          {
#ifndef DISABLE_TLS
	  deliver_set_expansions(addr);
#endif
          rc = do_callout(addr, host_list, &tf, callout, callout_overall,
            callout_connect, options, se_mailfrom, pm_mailfrom);
#ifndef DISABLE_TLS
	  deliver_set_expansions(NULL);
#endif
          }
        }
      else
        {
        HDEBUG(D_verify) debug_printf("Cannot do callout: neither router nor "
          "transport provided a host list, or transport is not smtp\n");
        }
      }
    }

  /* Otherwise, any failure is a routing failure */

  else *failure_ptr = US"route";

  /* A router may return REROUTED if it has set up a child address as a result
  of a change of domain name (typically from widening). In this case we always
  want to continue to verify the new child. */

  if (rc == REROUTED) continue;

  /* Handle hard failures */

  if (rc == FAIL)
    {
    allok = FALSE;
    if (fp)
      {
      address_item *p = addr->parent;

      respond_printf(fp, "%s%s %s", ko_prefix,
        full_info ? addr->address : address,
        f.address_test_mode ? "is undeliverable" : "failed to verify");
      if (!expn && f.admin_user)
        {
        if (addr->basic_errno > 0)
          respond_printf(fp, ": %s", strerror(addr->basic_errno));
        if (addr->message)
          respond_printf(fp, ": %s", addr->message);
        }

      /* Show parents iff doing full info */

      if (full_info) while (p)
        {
        respond_printf(fp, "%s\n    <-- %s", cr, p->address);
        p = p->parent;
        }
      respond_printf(fp, "%s\n", cr);
      }
    cancel_cutthrough_connection(TRUE, US"routing hard fail");

    if (!full_info)
      {
      yield = copy_error(vaddr, addr, FAIL);
      goto out;
      }
    yield = FAIL;
    }

  /* Soft failure */

  else if (rc == DEFER)
    {
    allok = FALSE;
    if (fp)
      {
      address_item *p = addr->parent;
      respond_printf(fp, "%s%s cannot be resolved at this time", ko_prefix,
        full_info? addr->address : address);
      if (!expn && f.admin_user)
        {
        if (addr->basic_errno > 0)
          respond_printf(fp, ": %s", strerror(addr->basic_errno));
        if (addr->message)
          respond_printf(fp, ": %s", addr->message);
        else if (addr->basic_errno <= 0)
          respond_printf(fp, ": unknown error");
        }

      /* Show parents iff doing full info */

      if (full_info) while (p)
        {
        respond_printf(fp, "%s\n    <-- %s", cr, p->address);
        p = p->parent;
        }
      respond_printf(fp, "%s\n", cr);
      }
    cancel_cutthrough_connection(TRUE, US"routing soft fail");

    if (!full_info)
      {
      yield = copy_error(vaddr, addr, DEFER);
      goto out;
      }
    if (yield == OK) yield = DEFER;
    }

  /* If we are handling EXPN, we do not want to continue to route beyond
  the top level (whose address is in "address"). */

  else if (expn)
    {
    uschar *ok_prefix = US"250-";

    if (!addr_new)
      if (!addr_local && !addr_remote)
        respond_printf(fp, "250 mail to <%s> is discarded\r\n", address);
      else
        respond_printf(fp, "250 <%s>\r\n", address);

    else do
      {
      address_item *addr2 = addr_new;
      addr_new = addr2->next;
      if (!addr_new) ok_prefix = US"250 ";
      respond_printf(fp, "%s<%s>\r\n", ok_prefix, addr2->address);
      } while (addr_new);
    yield = OK;
    goto out;
    }

  /* Successful routing other than EXPN. */

  else
    {
    /* Handle successful routing when short info wanted. Otherwise continue for
    other (generated) addresses. Short info is the operational case. Full info
    can be requested only when debug_selector != 0 and a file is supplied.

    There is a conflict between the use of aliasing as an alternate email
    address, and as a sort of mailing list. If an alias turns the incoming
    address into just one address (e.g. J.Caesar->jc44) you may well want to
    carry on verifying the generated address to ensure it is valid when
    checking incoming mail. If aliasing generates multiple addresses, you
    probably don't want to do this. Exim therefore treats the generation of
    just a single new address as a special case, and continues on to verify the
    generated address. */

    if (  !full_info			/* Stop if short info wanted AND */
       && (  (  !addr_new		/* No new address OR */
             || addr_new->next		/* More than one new address OR */
	     || testflag(addr_new, af_pfr)	/* New address is pfr */
	     )
          ||				/* OR */
             (  addr_new		/* At least one new address AND */
             && success_on_redirect	/* success_on_redirect is set */
	  )  )
       )
      {
      if (fp) fprintf(fp, "%s %s\n",
        address, f.address_test_mode ? "is deliverable" : "verified");

      /* If we have carried on to verify a child address, we want the value
      of $address_data to be that of the child */

      vaddr->prop.address_data = addr->prop.address_data;
      vaddr->prop.variables = NULL;
      tree_dup((tree_node **)&vaddr->prop.variables, addr->prop.variables);

      /* If stopped because more than one new address, cannot cutthrough */

      if (addr_new && addr_new->next)
	cancel_cutthrough_connection(TRUE, US"multiple addresses from routing");

      yield = OK;
      goto out;
      }
    }
  }     /* Loop for generated addresses */

/* Display the full results of the successful routing, including any generated
addresses. Control gets here only when full_info is set, which requires fp not
to be NULL, and this occurs only when a top-level verify is called with the
debugging switch on.

If there are no local and no remote addresses, and there were no pipes, files,
or autoreplies, and there were no errors or deferments, the message is to be
discarded, usually because of the use of :blackhole: in an alias file. */

if (allok && !addr_local && !addr_remote)
  {
  fprintf(fp, "mail to %s is discarded\n", address);
  goto out;
  }

for (addr_list = addr_local, i = 0; i < 2; addr_list = addr_remote, i++)
  while (addr_list)
    {
    address_item *addr = addr_list;
    transport_instance * tp = addr->transport;

    addr_list = addr->next;

    fprintf(fp, "%s", CS addr->address);
#ifdef EXPERIMENTAL_SRS
    if(addr->prop.srs_sender)
      fprintf(fp, "    [srs = %s]", addr->prop.srs_sender);
#endif

    /* If the address is a duplicate, show something about it. */

    if (!testflag(addr, af_pfr))
      {
      tree_node *tnode;
      if ((tnode = tree_search(tree_duplicates, addr->unique)))
        fprintf(fp, "   [duplicate, would not be delivered]");
      else tree_add_duplicate(addr->unique, addr);
      }

    /* Now show its parents */

    for (address_item * p = addr->parent; p; p = p->parent)
      fprintf(fp, "\n    <-- %s", p->address);
    fprintf(fp, "\n  ");

    /* Show router, and transport */

    fprintf(fp, "router = %s, transport = %s\n",
      addr->router->name, tp ? tp->name : US"unset");

    /* Show any hosts that are set up by a router unless the transport
    is going to override them; fiddle a bit to get a nice format. */

    if (addr->host_list && tp && !tp->overrides_hosts)
      {
      int maxlen = 0;
      int maxaddlen = 0;
      for (host_item * h = addr->host_list; h; h = h->next)
        {				/* get max lengths of host names, addrs */
        int len = Ustrlen(h->name);
        if (len > maxlen) maxlen = len;
        len = h->address ? Ustrlen(h->address) : 7;
        if (len > maxaddlen) maxaddlen = len;
        }
      for (host_item * h = addr->host_list; h; h = h->next)
	{
	fprintf(fp, "  host %-*s ", maxlen, h->name);

	if (h->address)
	  fprintf(fp, "[%s%-*c", h->address, maxaddlen+1 - Ustrlen(h->address), ']');
	else if (tp->info->local)
	  fprintf(fp, " %-*s ", maxaddlen, "");  /* Omit [unknown] for local */
	else
	  fprintf(fp, "[%s%-*c", "unknown", maxaddlen+1 - 7, ']');

        if (h->mx >= 0) fprintf(fp, " MX=%d", h->mx);
        if (h->port != PORT_NONE) fprintf(fp, " port=%d", h->port);
        if (f.running_in_test_harness  &&  h->dnssec == DS_YES) fputs(" AD", fp);
        if (h->status == hstatus_unusable) fputs(" ** unusable **", fp);
	fputc('\n', fp);
        }
      }
    }

/* Yield will be DEFER or FAIL if any one address has, only for full_info (which is
the -bv or -bt case). */

out:
verify_mode = NULL;
tls_modify_variables(&tls_in);	/* return variables to inbound values */

return yield;
}




/*************************************************
*      Check headers for syntax errors           *
*************************************************/

/* This function checks those header lines that contain addresses, and verifies
that all the addresses therein are 5322-syntactially correct.

Arguments:
  msgptr     where to put an error message

Returns:     OK
             FAIL
*/

int
verify_check_headers(uschar **msgptr)
{
uschar *colon, *s;
int yield = OK;

for (header_line * h = header_list; h && yield == OK; h = h->next)
  {
  if (h->type != htype_from &&
      h->type != htype_reply_to &&
      h->type != htype_sender &&
      h->type != htype_to &&
      h->type != htype_cc &&
      h->type != htype_bcc)
    continue;

  colon = Ustrchr(h->text, ':');
  s = colon + 1;
  Uskip_whitespace(&s);

  /* Loop for multiple addresses in the header, enabling group syntax. Note
  that we have to reset this after the header has been scanned. */

  f.parse_allow_group = TRUE;

  while (*s)
    {
    uschar *ss = parse_find_address_end(s, FALSE);
    uschar *recipient, *errmess;
    int terminator = *ss;
    int start, end, domain;

    /* Temporarily terminate the string at this point, and extract the
    operative address within, allowing group syntax. */

    *ss = 0;
    recipient = parse_extract_address(s,&errmess,&start,&end,&domain,FALSE);
    *ss = terminator;

    /* Permit an unqualified address only if the message is local, or if the
    sending host is configured to be permitted to send them. */

    if (recipient && !domain)
      {
      if (h->type == htype_from || h->type == htype_sender)
        {
        if (!f.allow_unqualified_sender) recipient = NULL;
        }
      else
        {
        if (!f.allow_unqualified_recipient) recipient = NULL;
        }
      if (!recipient) errmess = US"unqualified address not permitted";
      }

    /* It's an error if no address could be extracted, except for the special
    case of an empty address. */

    if (!recipient && Ustrcmp(errmess, "empty address") != 0)
      {
      uschar *verb = US"is";
      uschar *t = ss;
      uschar *tt = colon;
      int len;

      /* Arrange not to include any white space at the end in the
      error message or the header name. */

      while (t > s && isspace(t[-1])) t--;
      while (tt > h->text && isspace(tt[-1])) tt--;

      /* Add the address that failed to the error message, since in a
      header with very many addresses it is sometimes hard to spot
      which one is at fault. However, limit the amount of address to
      quote - cases have been seen where, for example, a missing double
      quote in a humungous To: header creates an "address" that is longer
      than string_sprintf can handle. */

      len = t - s;
      if (len > 1024)
        {
        len = 1024;
        verb = US"begins";
        }

      /* deconst cast ok as we're passing a non-const to string_printing() */
      *msgptr = US string_printing(
        string_sprintf("%s: failing address in \"%.*s:\" header %s: %.*s",
          errmess, (int)(tt - h->text), h->text, verb, len, s));

      yield = FAIL;
      break;          /* Out of address loop */
      }

    /* Advance to the next address */

    s = ss + (terminator ? 1 : 0);
    Uskip_whitespace(&s);
    }   /* Next address */

  f.parse_allow_group = FALSE;
  f.parse_found_group = FALSE;
  }     /* Next header unless yield has been set FALSE */

return yield;
}


/*************************************************
*      Check header names for 8-bit characters   *
*************************************************/

/* This function checks for invalid characters in header names. See
RFC 5322, 2.2. and RFC 6532, 3.

Arguments:
  msgptr     where to put an error message

Returns:     OK
             FAIL
*/

int
verify_check_header_names_ascii(uschar **msgptr)
{
uschar *colon;

for (header_line * h = header_list; h; h = h->next)
  {
  colon = Ustrchr(h->text, ':');
  for(uschar * s = h->text; s < colon; s++)
    if ((*s < 33) || (*s > 126))
      {
      *msgptr = string_sprintf("Invalid character in header \"%.*s\" found",
			     (int)(colon - h->text), h->text);
      return FAIL;
      }
  }
return OK;
}

/*************************************************
*          Check for blind recipients            *
*************************************************/

/* This function checks that every (envelope) recipient is mentioned in either
the To: or Cc: header lines, thus detecting blind carbon copies.

There are two ways of scanning that could be used: either scan the header lines
and tick off the recipients, or scan the recipients and check the header lines.
The original proposed patch did the former, but I have chosen to do the latter,
because (a) it requires no memory and (b) will use fewer resources when there
are many addresses in To: and/or Cc: and only one or two envelope recipients.

Arguments:   case_sensitive   true if case sensitive matching should be used
Returns:     OK    if there are no blind recipients
             FAIL  if there is at least one blind recipient
*/

int
verify_check_notblind(BOOL case_sensitive)
{
for (int i = 0; i < recipients_count; i++)
  {
  BOOL found = FALSE;
  uschar *address = recipients_list[i].address;

  for (header_line * h = header_list; !found && h; h = h->next)
    {
    uschar *colon, *s;

    if (h->type != htype_to && h->type != htype_cc) continue;

    colon = Ustrchr(h->text, ':');
    s = colon + 1;
    Uskip_whitespace(&s);

    /* Loop for multiple addresses in the header, enabling group syntax. Note
    that we have to reset this after the header has been scanned. */

    f.parse_allow_group = TRUE;

    while (*s)
      {
      uschar * ss = parse_find_address_end(s, FALSE);
      uschar * recipient, * errmess;
      int terminator = *ss;
      int start, end, domain;

      /* Temporarily terminate the string at this point, and extract the
      operative address within, allowing group syntax. */

      *ss = 0;
      recipient = parse_extract_address(s,&errmess,&start,&end,&domain,FALSE);
      *ss = terminator;

      /* If we found a valid recipient that has a domain, compare it with the
      envelope recipient. Local parts are compared with case-sensitivity
      according to the routine arg, domains case-insensitively.
      By comparing from the start with length "domain", we include the "@" at
      the end, which ensures that we are comparing the whole local part of each
      address. */

      if (recipient && domain != 0)
        if ((found = (case_sensitive
		? Ustrncmp(recipient, address, domain) == 0
		: strncmpic(recipient, address, domain) == 0)
	      && strcmpic(recipient + domain, address + domain) == 0))
	  break;

      /* Advance to the next address */

      s = ss + (terminator ? 1:0);
      Uskip_whitespace(&s);
      }   /* Next address */

    f.parse_allow_group = FALSE;
    f.parse_found_group = FALSE;
    }     /* Next header (if found is false) */

  if (!found) return FAIL;
  }       /* Next recipient */

return OK;
}



/*************************************************
*          Find if verified sender               *
*************************************************/

/* Usually, just a single address is verified as the sender of the message.
However, Exim can be made to verify other addresses as well (often related in
some way), and this is useful in some environments. There may therefore be a
chain of such addresses that have previously been tested. This function finds
whether a given address is on the chain.

Arguments:   the address to be verified
Returns:     pointer to an address item, or NULL
*/

address_item *
verify_checked_sender(uschar *sender)
{
for (address_item * addr = sender_verified_list; addr; addr = addr->next)
  if (Ustrcmp(sender, addr->address) == 0) return addr;
return NULL;
}





/*************************************************
*             Get valid header address           *
*************************************************/

/* Scan the originator headers of the message, looking for an address that
verifies successfully. RFC 822 says:

    o   The "Sender" field mailbox should be sent  notices  of
        any  problems in transport or delivery of the original
        messages.  If there is no  "Sender"  field,  then  the
        "From" field mailbox should be used.

    o   If the "Reply-To" field exists, then the reply  should
        go to the addresses indicated in that field and not to
        the address(es) indicated in the "From" field.

So we check a Sender field if there is one, else a Reply_to field, else a From
field. As some strange messages may have more than one of these fields,
especially if they are resent- fields, check all of them if there is more than
one.

Arguments:
  user_msgptr      points to where to put a user error message
  log_msgptr       points to where to put a log error message
  callout          timeout for callout check (passed to verify_address())
  callout_overall  overall callout timeout (ditto)
  callout_connect  connect callout timeout (ditto)
  se_mailfrom      mailfrom for verify; NULL => ""
  pm_mailfrom      sender for pm callout check (passed to verify_address())
  options          callout options (passed to verify_address())
  verrno           where to put the address basic_errno

If log_msgptr is set to something without setting user_msgptr, the caller
normally uses log_msgptr for both things.

Returns:           result of the verification attempt: OK, FAIL, or DEFER;
                   FAIL is given if no appropriate headers are found
*/

int
verify_check_header_address(uschar **user_msgptr, uschar **log_msgptr,
  int callout, int callout_overall, int callout_connect, uschar *se_mailfrom,
  uschar *pm_mailfrom, int options, int *verrno)
{
static int header_types[] = { htype_sender, htype_reply_to, htype_from };
BOOL done = FALSE;
int yield = FAIL;

for (int i = 0; i < 3 && !done; i++)
  for (header_line * h = header_list; h != NULL && !done; h = h->next)
    {
    int terminator, new_ok;
    uschar *s, *ss, *endname;

    if (h->type != header_types[i]) continue;
    s = endname = Ustrchr(h->text, ':') + 1;

    /* Scan the addresses in the header, enabling group syntax. Note that we
    have to reset this after the header has been scanned. */

    f.parse_allow_group = TRUE;

    while (*s != 0)
      {
      address_item *vaddr;

      while (isspace(*s) || *s == ',') s++;
      if (*s == 0) break;        /* End of header */

      ss = parse_find_address_end(s, FALSE);

      /* The terminator is a comma or end of header, but there may be white
      space preceding it (including newline for the last address). Move back
      past any white space so we can check against any cached envelope sender
      address verifications. */

      while (isspace(ss[-1])) ss--;
      terminator = *ss;
      *ss = 0;

      HDEBUG(D_verify) debug_printf("verifying %.*s header address %s\n",
        (int)(endname - h->text), h->text, s);

      /* See if we have already verified this address as an envelope sender,
      and if so, use the previous answer. */

      vaddr = verify_checked_sender(s);

      if (vaddr != NULL &&                   /* Previously checked */
           (callout <= 0 ||                  /* No callout needed; OR */
            vaddr->special_action > 256))    /* Callout was done */
        {
        new_ok = vaddr->special_action & 255;
        HDEBUG(D_verify) debug_printf("previously checked as envelope sender\n");
        *ss = terminator;  /* Restore shortened string */
        }

      /* Otherwise we run the verification now. We must restore the shortened
      string before running the verification, so the headers are correct, in
      case there is any rewriting. */

      else
        {
        int start, end, domain;
        uschar *address = parse_extract_address(s, log_msgptr, &start, &end,
          &domain, FALSE);

        *ss = terminator;

        /* If we found an empty address, just carry on with the next one, but
        kill the message. */

        if (!address && Ustrcmp(*log_msgptr, "empty address") == 0)
          {
          *log_msgptr = NULL;
          s = ss;
          continue;
          }

        /* If verification failed because of a syntax error, fail this
        function, and ensure that the failing address gets added to the error
        message. */

        if (!address)
          {
          new_ok = FAIL;
          while (ss > s && isspace(ss[-1])) ss--;
          *log_msgptr = string_sprintf("syntax error in '%.*s' header when "
            "scanning for sender: %s in \"%.*s\"",
            (int)(endname - h->text), h->text, *log_msgptr, (int)(ss - s), s);
          yield = FAIL;
          done = TRUE;
          break;
          }

        /* Else go ahead with the sender verification. But it isn't *the*
        sender of the message, so set vopt_fake_sender to stop sender_address
        being replaced after rewriting or qualification. */

        else
          {
          vaddr = deliver_make_addr(address, FALSE);
          new_ok = verify_address(vaddr, NULL, options | vopt_fake_sender,
            callout, callout_overall, callout_connect, se_mailfrom,
            pm_mailfrom, NULL);
          }
        }

      /* We now have the result, either newly found, or cached. If we are
      giving out error details, set a specific user error. This means that the
      last of these will be returned to the user if all three fail. We do not
      set a log message - the generic one below will be used. */

      if (new_ok != OK)
        {
        *verrno = vaddr->basic_errno;
        if (smtp_return_error_details)
          *user_msgptr = string_sprintf("Rejected after DATA: "
            "could not verify \"%.*s\" header address\n%s: %s",
            (int)(endname - h->text), h->text, vaddr->address, vaddr->message);
        }

      /* Success or defer */

      if (new_ok == OK)
        {
        yield = OK;
        done = TRUE;
        break;
        }

      if (new_ok == DEFER) yield = DEFER;

      /* Move on to any more addresses in the header */

      s = ss;
      }     /* Next address */

    f.parse_allow_group = FALSE;
    f.parse_found_group = FALSE;
    }       /* Next header, unless done */
	    /* Next header type unless done */

if (yield == FAIL && *log_msgptr == NULL)
  *log_msgptr = US"there is no valid sender in any header line";

if (yield == DEFER && *log_msgptr == NULL)
  *log_msgptr = US"all attempts to verify a sender in a header line deferred";

return yield;
}




/*************************************************
*            Get RFC 1413 identification         *
*************************************************/

/* Attempt to get an id from the sending machine via the RFC 1413 protocol. If
the timeout is set to zero, then the query is not done. There may also be lists
of hosts and nets which are exempt. To guard against malefactors sending
non-printing characters which could, for example, disrupt a message's headers,
make sure the string consists of printing characters only.

Argument:
  port    the port to connect to; usually this is IDENT_PORT (113), but when
          running in the test harness with -bh a different value is used.

Returns:  nothing

Side effect: any received ident value is put in sender_ident (NULL otherwise)
*/

void
verify_get_ident(int port)
{
client_conn_ctx ident_conn_ctx = {0};
int host_af, qlen;
int received_sender_port, received_interface_port, n;
uschar *p;
blob early_data;
uschar buffer[2048];

/* Default is no ident. Check whether we want to do an ident check for this
host. */

sender_ident = NULL;
if (rfc1413_query_timeout <= 0 || verify_check_host(&rfc1413_hosts) != OK)
  return;

DEBUG(D_ident) debug_printf("doing ident callback\n");

/* Set up a connection to the ident port of the remote host. Bind the local end
to the incoming interface address. If the sender host address is an IPv6
address, the incoming interface address will also be IPv6. */

host_af = Ustrchr(sender_host_address, ':') == NULL ? AF_INET : AF_INET6;
if ((ident_conn_ctx.sock = ip_socket(SOCK_STREAM, host_af)) < 0) return;

if (ip_bind(ident_conn_ctx.sock, host_af, interface_address, 0) < 0)
  {
  DEBUG(D_ident) debug_printf("bind socket for ident failed: %s\n",
    strerror(errno));
  goto END_OFF;
  }

/* Construct and send the query. */

qlen = snprintf(CS buffer, sizeof(buffer), "%d , %d\r\n",
  sender_host_port, interface_port);
early_data.data = buffer;
early_data.len = qlen;

/*XXX we trust that the query is idempotent */
if (ip_connect(ident_conn_ctx.sock, host_af, sender_host_address, port,
		rfc1413_query_timeout, &early_data) < 0)
  {
  if (errno == ETIMEDOUT && LOGGING(ident_timeout))
    log_write(0, LOG_MAIN, "ident connection to %s timed out",
      sender_host_address);
  else
    DEBUG(D_ident) debug_printf("ident connection to %s failed: %s\n",
      sender_host_address, strerror(errno));
  goto END_OFF;
  }

/* Read a response line. We put it into the rest of the buffer, using several
recv() calls if necessary. */

p = buffer + qlen;

for (;;)
  {
  uschar *pp;
  int count;
  int size = sizeof(buffer) - (p - buffer);

  if (size <= 0) goto END_OFF;   /* Buffer filled without seeing \n. */
  count = ip_recv(&ident_conn_ctx, p, size, time(NULL) + rfc1413_query_timeout);
  if (count <= 0) goto END_OFF;  /* Read error or EOF */

  /* Scan what we just read, to see if we have reached the terminating \r\n. Be
  generous, and accept a plain \n terminator as well. The only illegal
  character is 0. */

  for (pp = p; pp < p + count; pp++)
    {
    if (*pp == 0) goto END_OFF;   /* Zero octet not allowed */
    if (*pp == '\n')
      {
      if (pp[-1] == '\r') pp--;
      *pp = 0;
      goto GOT_DATA;             /* Break out of both loops */
      }
    }

  /* Reached the end of the data without finding \n. Let the loop continue to
  read some more, if there is room. */

  p = pp;
  }

GOT_DATA:

/* We have received a line of data. Check it carefully. It must start with the
same two port numbers that we sent, followed by data as defined by the RFC. For
example,

  12345 , 25 : USERID : UNIX :root

However, the amount of white space may be different to what we sent. In the
"osname" field there may be several sub-fields, comma separated. The data we
actually want to save follows the third colon. Some systems put leading spaces
in it - we discard those. */

if (sscanf(CS buffer + qlen, "%d , %d%n", &received_sender_port,
      &received_interface_port, &n) != 2 ||
    received_sender_port != sender_host_port ||
    received_interface_port != interface_port)
  goto END_OFF;

p = buffer + qlen + n;
while(isspace(*p)) p++;
if (*p++ != ':') goto END_OFF;
while(isspace(*p)) p++;
if (Ustrncmp(p, "USERID", 6) != 0) goto END_OFF;
p += 6;
while(isspace(*p)) p++;
if (*p++ != ':') goto END_OFF;
while (*p != 0 && *p != ':') p++;
if (*p++ == 0) goto END_OFF;
while(isspace(*p)) p++;
if (*p == 0) goto END_OFF;

/* The rest of the line is the data we want. We turn it into printing
characters when we save it, so that it cannot mess up the format of any logging
or Received: lines into which it gets inserted. We keep a maximum of 127
characters. The deconst cast is ok as we fed a nonconst to string_printing() */

sender_ident = US string_printing(string_copyn(p, 127));
DEBUG(D_ident) debug_printf("sender_ident = %s\n", sender_ident);

END_OFF:
(void)close(ident_conn_ctx.sock);
return;
}




/*************************************************
*      Match host to a single host-list item     *
*************************************************/

/* This function compares a host (name or address) against a single item
from a host list. The host name gets looked up if it is needed and is not
already known. The function is called from verify_check_this_host() via
match_check_list(), which is why most of its arguments are in a single block.

Arguments:
  arg            the argument block (see below)
  ss             the host-list item
  valueptr       where to pass back looked up data, or NULL
  error          for error message when returning ERROR

The block contains:
  host_name      (a) the host name, or
                 (b) NULL, implying use sender_host_name and
                       sender_host_aliases, looking them up if required, or
                 (c) the empty string, meaning that only IP address matches
                       are permitted
  host_address   the host address
  host_ipv4      the IPv4 address taken from an IPv6 one

Returns:         OK      matched
                 FAIL    did not match
                 DEFER   lookup deferred
                 ERROR   (a) failed to find the host name or IP address, or
                         (b) unknown lookup type specified, or
                         (c) host name encountered when only IP addresses are
                               being matched
*/

int
check_host(void *arg, const uschar *ss, const uschar **valueptr, uschar **error)
{
check_host_block *cb = (check_host_block *)arg;
int mlen = -1;
int maskoffset;
BOOL iplookup = FALSE;
BOOL isquery = FALSE;
BOOL isiponly = cb->host_name != NULL && cb->host_name[0] == 0;
const uschar *t;
uschar * semicolon, * endname, * opts;
uschar **aliases;

/* Optimize for the special case when the pattern is "*". */

if (*ss == '*' && ss[1] == 0) return OK;

/* If the pattern is empty, it matches only in the case when there is no host -
this can occur in ACL checking for SMTP input using the -bs option. In this
situation, the host address is the empty string. */

if (cb->host_address[0] == 0) return (*ss == 0)? OK : FAIL;
if (*ss == 0) return FAIL;

/* If the pattern is precisely "@" then match against the primary host name,
provided that host name matching is permitted; if it's "@[]" match against the
local host's IP addresses. */

if (*ss == '@')
  if (ss[1] == 0)
    {
    if (isiponly) return ERROR;
    ss = primary_hostname;
    }
  else if (Ustrcmp(ss, "@[]") == 0)
    {
    for (ip_address_item * ip = host_find_interfaces(); ip; ip = ip->next)
      if (Ustrcmp(ip->address, cb->host_address) == 0) return OK;
    return FAIL;
    }

/* If the pattern is an IP address, optionally followed by a bitmask count, do
a (possibly masked) comparison with the current IP address. */

if (string_is_ip_address(ss, &maskoffset) != 0)
  return (host_is_in_net(cb->host_address, ss, maskoffset)? OK : FAIL);

/* The pattern is not an IP address. A common error that people make is to omit
one component of an IPv4 address, either by accident, or believing that, for
example, 1.2.3/24 is the same as 1.2.3.0/24, or 1.2.3 is the same as 1.2.3.0,
which it isn't. (Those applications that do accept 1.2.3 as an IP address
interpret it as 1.2.0.3 because the final component becomes 16-bit - this is an
ancient specification.) To aid in debugging these cases, we give a specific
error if the pattern contains only digits and dots or contains a slash preceded
only by digits and dots (a slash at the start indicates a file name and of
course slashes may be present in lookups, but not preceded only by digits and
dots). */

for (t = ss; isdigit(*t) || *t == '.'; ) t++;
if (*t == 0 || (*t == '/' && t != ss))
  {
  *error = US"malformed IPv4 address or address mask";
  return ERROR;
  }

/* See if there is a semicolon in the pattern, separating a searchtype
prefix.  If there is one then check for comma-sep options. */

if ((semicolon = Ustrchr(ss, ';')))
  if ((opts = Ustrchr(ss, ',')) && opts < semicolon)
    {
    endname = opts++;
    opts = string_copyn(opts, semicolon - opts);
    }
  else
    {
    endname = semicolon;
    opts = NULL;
    }

/* If we are doing an IP address only match, then all lookups must be IP
address lookups, even if there is no "net-". */

if (isiponly)
  iplookup = semicolon != NULL;

/* Otherwise, if the item is of the form net[n]-lookup;<file|query> then it is
a lookup on a masked IP network, in textual form. We obey this code even if we
have already set iplookup, so as to skip over the "net-" prefix and to set the
mask length. The net- stuff really only applies to single-key lookups where the
key is implicit. For query-style lookups the key is specified in the query.
From release 4.30, the use of net- for query style is no longer needed, but we
retain it for backward compatibility. */

if (Ustrncmp(ss, "net", 3) == 0 && semicolon)
  {
  mlen = 0;
  for (t = ss + 3; isdigit(*t); t++) mlen = mlen * 10 + *t - '0';
  if (mlen == 0 && t == ss+3) mlen = -1;  /* No mask supplied */
  iplookup = *t++ == '-';
  }
else
  t = ss;

/* Do the IP address lookup if that is indeed what we have */

if (iplookup)
  {
  int insize;
  int search_type;
  int incoming[4];
  void *handle;
  uschar *filename, *key, *result;
  uschar buffer[64];

  /* Find the search type */

  search_type = search_findtype(t, endname - t);

  if (search_type < 0) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "%s",
    search_error_message);

  /* Adjust parameters for the type of lookup. For a query-style lookup, there
  is no file name, and the "key" is just the query. For query-style with a file
  name, we have to fish the file off the start of the query. For a single-key
  lookup, the key is the current IP address, masked appropriately, and
  reconverted to text form, with the mask appended. For IPv6 addresses, specify
  dot separators instead of colons, except when the lookup type is "iplsearch".
  */

  if (mac_islookup(search_type, lookup_absfilequery))
    {
    filename = semicolon + 1;
    key = filename;
    while (*key != 0 && !isspace(*key)) key++;
    filename = string_copyn(filename, key - filename);
    while (isspace(*key)) key++;
    }
  else if (mac_islookup(search_type, lookup_querystyle))
    {
    filename = NULL;
    key = semicolon + 1;
    }
  else   /* Single-key style */
    {
    int sep = (Ustrcmp(lookup_list[search_type]->name, "iplsearch") == 0)?
      ':' : '.';
    insize = host_aton(cb->host_address, incoming);
    host_mask(insize, incoming, mlen);
    (void)host_nmtoa(insize, incoming, mlen, buffer, sep);
    key = buffer;
    filename = semicolon + 1;
    }

  /* Now do the actual lookup; note that there is no search_close() because
  of the caching arrangements. */

  if (!(handle = search_open(filename, search_type, 0, NULL, NULL)))
    log_write(0, LOG_MAIN|LOG_PANIC_DIE, "%s", search_error_message);

  result = search_find(handle, filename, key, -1, NULL, 0, 0, NULL, opts);
  if (valueptr) *valueptr = result;
  return result ? OK : f.search_find_defer ? DEFER: FAIL;
  }

/* The pattern is not an IP address or network reference of any kind. That is,
it is a host name pattern. If this is an IP only match, there's an error in the
host list. */

if (isiponly)
  {
  *error = US"cannot match host name in match_ip list";
  return ERROR;
  }

/* Check the characters of the pattern to see if they comprise only letters,
digits, full stops, and hyphens (the constituents of domain names). Allow
underscores, as they are all too commonly found. Sigh. Also, if
allow_utf8_domains is set, allow top-bit characters. */

for (t = ss; *t != 0; t++)
  if (!isalnum(*t) && *t != '.' && *t != '-' && *t != '_' &&
      (!allow_utf8_domains || *t < 128)) break;

/* If the pattern is a complete domain name, with no fancy characters, look up
its IP address and match against that. Note that a multi-homed host will add
items to the chain. */

if (*t == 0)
  {
  int rc;
  host_item h;
  h.next = NULL;
  h.name = ss;
  h.address = NULL;
  h.mx = MX_NONE;

  /* Using byname rather than bydns here means we cannot determine dnssec
  status.  On the other hand it is unclear how that could be either
  propagated up or enforced. */

  rc = host_find_byname(&h, NULL, HOST_FIND_QUALIFY_SINGLE, NULL, FALSE);
  if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
    {
    for (host_item * hh = &h; hh; hh = hh->next)
      if (host_is_in_net(hh->address, cb->host_address, 0)) return OK;
    return FAIL;
    }
  if (rc == HOST_FIND_AGAIN) return DEFER;
  *error = string_sprintf("failed to find IP address for %s", ss);
  return ERROR;
  }

/* Almost all subsequent comparisons require the host name, and can be done
using the general string matching function. When this function is called for
outgoing hosts, the name is always given explicitly. If it is NULL, it means we
must use sender_host_name and its aliases, looking them up if necessary. */

if (cb->host_name)   /* Explicit host name given */
  return match_check_string(cb->host_name, ss, -1, TRUE, TRUE, TRUE,
    valueptr);

/* Host name not given; in principle we need the sender host name and its
aliases. However, for query-style lookups, we do not need the name if the
query does not contain $sender_host_name. From release 4.23, a reference to
$sender_host_name causes it to be looked up, so we don't need to do the lookup
on spec. */

if ((semicolon = Ustrchr(ss, ';')))
  {
  const uschar * affix, * opts;
  int partial, affixlen, starflags, id;

  *semicolon = 0;
  id = search_findtype_partial(ss, &partial, &affix, &affixlen, &starflags,
	  &opts);
  *semicolon=';';

  if (id < 0)                           /* Unknown lookup type */
    {
    log_write(0, LOG_MAIN|LOG_PANIC, "%s in host list item \"%s\"",
      search_error_message, ss);
    return DEFER;
    }
  isquery = mac_islookup(id, lookup_querystyle|lookup_absfilequery);
  }

if (isquery)
  {
  switch(match_check_string(US"", ss, -1, TRUE, TRUE, TRUE, valueptr))
    {
    case OK:    return OK;
    case DEFER: return DEFER;
    default:    return FAIL;
    }
  }

/* Not a query-style lookup; must ensure the host name is present, and then we
do a check on the name and all its aliases. */

if (!sender_host_name)
  {
  HDEBUG(D_host_lookup)
    debug_printf("sender host name required, to match against %s\n", ss);
  if (host_lookup_failed || host_name_lookup() != OK)
    {
    *error = string_sprintf("failed to find host name for %s",
      sender_host_address);;
    return ERROR;
    }
  host_build_sender_fullhost();
  }

/* Match on the sender host name, using the general matching function */

switch(match_check_string(sender_host_name, ss, -1, TRUE, TRUE, TRUE, valueptr))
  {
  case OK:    return OK;
  case DEFER: return DEFER;
  }

/* If there are aliases, try matching on them. */

aliases = sender_host_aliases;
while (*aliases)
  switch(match_check_string(*aliases++, ss, -1, TRUE, TRUE, TRUE, valueptr))
    {
    case OK:    return OK;
    case DEFER: return DEFER;
    }
return FAIL;
}




/*************************************************
*    Check a specific host matches a host list   *
*************************************************/

/* This function is passed a host list containing items in a number of
different formats and the identity of a host. Its job is to determine whether
the given host is in the set of hosts defined by the list. The host name is
passed as a pointer so that it can be looked up if needed and not already
known. This is commonly the case when called from verify_check_host() to check
an incoming connection. When called from elsewhere the host name should usually
be set.

This function is now just a front end to match_check_list(), which runs common
code for scanning a list. We pass it the check_host() function to perform a
single test.

Arguments:
  listptr              pointer to the host list
  cache_bits           pointer to cache for named lists, or NULL
  host_name            the host name or NULL, implying use sender_host_name and
                         sender_host_aliases, looking them up if required
  host_address         the IP address
  valueptr             if not NULL, data from a lookup is passed back here

Returns:    OK    if the host is in the defined set
            FAIL  if the host is not in the defined set,
            DEFER if a data lookup deferred (not a host lookup)

If the host name was needed in order to make a comparison, and could not be
determined from the IP address, the result is FAIL unless the item
"+allow_unknown" was met earlier in the list, in which case OK is returned. */

int
verify_check_this_host(const uschar **listptr, unsigned int *cache_bits,
  const uschar *host_name, const uschar *host_address, const uschar **valueptr)
{
int rc;
unsigned int *local_cache_bits = cache_bits;
const uschar *save_host_address = deliver_host_address;
check_host_block cb = { .host_name = host_name, .host_address = host_address };

if (valueptr) *valueptr = NULL;

/* If the host address starts off ::ffff: it is an IPv6 address in
IPv4-compatible mode. Find the IPv4 part for checking against IPv4
addresses. */

cb.host_ipv4 = Ustrncmp(host_address, "::ffff:", 7) == 0
  ? host_address + 7 : host_address;

/* During the running of the check, put the IP address into $host_address. In
the case of calls from the smtp transport, it will already be there. However,
in other calls (e.g. when testing ignore_target_hosts), it won't. Just to be on
the safe side, any existing setting is preserved, though as I write this
(November 2004) I can't see any cases where it is actually needed. */

deliver_host_address = host_address;
rc = match_check_list(
       listptr,                                /* the list */
       0,                                      /* separator character */
       &hostlist_anchor,                       /* anchor pointer */
       &local_cache_bits,                      /* cache pointer */
       check_host,                             /* function for testing */
       &cb,                                    /* argument for function */
       MCL_HOST,                               /* type of check */
       (host_address == sender_host_address)?
         US"host" : host_address,              /* text for debugging */
       valueptr);                              /* where to pass back data */
deliver_host_address = save_host_address;
return rc;
}




/*************************************************
*      Check the given host item matches a list  *
*************************************************/
int
verify_check_given_host(const uschar **listptr, const host_item *host)
{
return verify_check_this_host(listptr, NULL, host->name, host->address, NULL);
}

/*************************************************
*      Check the remote host matches a list      *
*************************************************/

/* This is a front end to verify_check_this_host(), created because checking
the remote host is a common occurrence. With luck, a good compiler will spot
the tail recursion and optimize it. If there's no host address, this is
command-line SMTP input - check against an empty string for the address.

Arguments:
  listptr              pointer to the host list

Returns:               the yield of verify_check_this_host(),
                       i.e. OK, FAIL, or DEFER
*/

int
verify_check_host(uschar **listptr)
{
return verify_check_this_host(CUSS listptr, sender_host_cache, NULL,
  sender_host_address ? sender_host_address : US"", NULL);
}





/*************************************************
*              Invert an IP address              *
*************************************************/

/* Originally just used for DNS xBL lists, now also used for the
reverse_ip expansion operator.

Arguments:
  buffer         where to put the answer
  address        the address to invert
*/

void
invert_address(uschar *buffer, uschar *address)
{
int bin[4];
uschar *bptr = buffer;

/* If this is an IPv4 address mapped into IPv6 format, adjust the pointer
to the IPv4 part only. */

if (Ustrncmp(address, "::ffff:", 7) == 0) address += 7;

/* Handle IPv4 address: when HAVE_IPV6 is false, the result of host_aton() is
always 1. */

if (host_aton(address, bin) == 1)
  {
  int x = bin[0];
  for (int i = 0; i < 4; i++)
    {
    sprintf(CS bptr, "%d.", x & 255);
    while (*bptr) bptr++;
    x >>= 8;
    }
  }

/* Handle IPv6 address. Actually, as far as I know, there are no IPv6 addresses
in any DNS black lists, and the format in which they will be looked up is
unknown. This is just a guess. */

#if HAVE_IPV6
else
  for (int j = 3; j >= 0; j--)
    {
    int x = bin[j];
    for (int i = 0; i < 8; i++)
      {
      sprintf(CS bptr, "%x.", x & 15);
      while (*bptr) bptr++;
      x >>= 4;
      }
    }
#endif

/* Remove trailing period -- this is needed so that both arbitrary
dnsbl keydomains and inverted addresses may be combined with the
same format string, "%s.%s" */

*(--bptr) = 0;
}



/*************************************************
*          Perform a single dnsbl lookup         *
*************************************************/

/* This function is called from verify_check_dnsbl() below. It is also called
recursively from within itself when domain and domain_txt are different
pointers, in order to get the TXT record from the alternate domain.

Arguments:
  domain         the outer dnsbl domain
  domain_txt     alternate domain to lookup TXT record on success; when the
                   same domain is to be used, domain_txt == domain (that is,
                   the pointers must be identical, not just the text)
  keydomain      the current keydomain (for debug message)
  prepend        subdomain to lookup (like keydomain, but
                   reversed if IP address)
  iplist         the list of matching IP addresses, or NULL for "any"
  bitmask        true if bitmask matching is wanted
  match_type     condition for 'succeed' result
                   0 => Any RR in iplist     (=)
                   1 => No RR in iplist      (!=)
                   2 => All RRs in iplist    (==)
                   3 => Some RRs not in iplist (!==)
                   the two bits are defined as MT_NOT and MT_ALL
  defer_return   what to return for a defer

Returns:         OK if lookup succeeded
                 FAIL if not
*/

static int
one_check_dnsbl(uschar *domain, uschar *domain_txt, uschar *keydomain,
  uschar *prepend, uschar *iplist, BOOL bitmask, int match_type,
  int defer_return)
{
dns_answer * dnsa = store_get_dns_answer();
dns_scan dnss;
tree_node *t;
dnsbl_cache_block *cb;
int old_pool = store_pool;
uschar * query;
int qlen;

/* Construct the specific query domainname */

query = string_sprintf("%s.%s", prepend, domain);
if ((qlen = Ustrlen(query)) >= 256)
  {
  log_write(0, LOG_MAIN|LOG_PANIC, "dnslist query is too long "
    "(ignored): %s...", query);
  return FAIL;
  }

/* Look for this query in the cache. */

if (  (t = tree_search(dnsbl_cache, query))
   && (cb = t->data.ptr)->expiry > time(NULL)
   )

/* Previous lookup was cached */

  {
  HDEBUG(D_dnsbl) debug_printf("dnslists: using result of previous lookup\n");
  }

/* If not cached from a previous lookup, we must do a DNS lookup, and
cache the result in permanent memory. */

else
  {
  uint ttl = 3600;	/* max TTL for positive cache entries */

  store_pool = POOL_PERM;

  if (t)
    {
    HDEBUG(D_dnsbl) debug_printf("cached data found but past valid time; ");
    }

  else
    {	/* Set up a tree entry to cache the lookup */
    t = store_get(sizeof(tree_node) + qlen + 1 + 1, is_tainted(query));
    Ustrcpy(t->name, query);
    t->data.ptr = cb = store_get(sizeof(dnsbl_cache_block), FALSE);
    (void)tree_insertnode(&dnsbl_cache, t);
    }

  /* Do the DNS lookup . */

  HDEBUG(D_dnsbl) debug_printf("new DNS lookup for %s\n", query);
  cb->rc = dns_basic_lookup(dnsa, query, T_A);
  cb->text_set = FALSE;
  cb->text = NULL;
  cb->rhs = NULL;

  /* If the lookup succeeded, cache the RHS address. The code allows for
  more than one address - this was for complete generality and the possible
  use of A6 records. However, A6 records are no longer supported. Leave the code
  here, just in case.

  Quite apart from one A6 RR generating multiple addresses, there are DNS
  lists that return more than one A record, so we must handle multiple
  addresses generated in that way as well.

  Mark the cache entry with the "now" plus the minimum of the address TTLs,
  or the RFC 2308 negative-cache value from the SOA if none were found. */

  switch (cb->rc)
    {
    case DNS_SUCCEED:
      {
      dns_address ** addrp = &cb->rhs;
      dns_address * da;
      for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
	   rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
	if (rr->type == T_A && (da = dns_address_from_rr(dnsa, rr)))
	  {
	  *addrp = da;
	  while (da->next) da = da->next;
	  addrp = &da->next;
	  if (ttl > rr->ttl) ttl = rr->ttl;
	  }

      if (cb->rhs)
	{
	cb->expiry = time(NULL) + ttl;
	break;
	}

      /* If we didn't find any A records, change the return code. This can
      happen when there is a CNAME record but there are no A records for what
      it points to. */

      cb->rc = DNS_NODATA;
      }
      /*FALLTHROUGH*/

    case DNS_NOMATCH:
    case DNS_NODATA:
      {
      /* Although there already is a neg-cache layer maintained by
      dns_basic_lookup(), we have a dnslist cache entry allocated and
      tree-inserted. So we may as well use it. */

      time_t soa_negttl = dns_expire_from_soa(dnsa, T_A);
      cb->expiry = soa_negttl ? soa_negttl : time(NULL) + ttl;
      break;
      }

    default:
      cb->expiry = time(NULL) + ttl;
      break;
    }

  store_pool = old_pool;
  HDEBUG(D_dnsbl) debug_printf("dnslists: wrote cache entry, ttl=%d\n",
    (int)(cb->expiry - time(NULL)));
  }

/* We now have the result of the DNS lookup, either newly done, or cached
from a previous call. If the lookup succeeded, check against the address
list if there is one. This may be a positive equality list (introduced by
"="), a negative equality list (introduced by "!="), a positive bitmask
list (introduced by "&"), or a negative bitmask list (introduced by "!&").*/

if (cb->rc == DNS_SUCCEED)
  {
  dns_address * da = NULL;
  uschar *addlist = cb->rhs->address;

  /* For A and AAAA records, there may be multiple addresses from multiple
  records. For A6 records (currently not expected to be used) there may be
  multiple addresses from a single record. */

  for (da = cb->rhs->next; da; da = da->next)
    addlist = string_sprintf("%s, %s", addlist, da->address);

  HDEBUG(D_dnsbl) debug_printf("DNS lookup for %s succeeded (yielding %s)\n",
    query, addlist);

  /* Address list check; this can be either for equality, or via a bitmask.
  In the latter case, all the bits must match. */

  if (iplist)
    {
    for (da = cb->rhs; da; da = da->next)
      {
      int ipsep = ',';
      const uschar *ptr = iplist;
      uschar *res;

      /* Handle exact matching */

      if (!bitmask)
	{
        while ((res = string_nextinlist(&ptr, &ipsep, NULL, 0)))
          if (Ustrcmp(CS da->address, res) == 0)
	    break;
	}

      /* Handle bitmask matching */

      else
        {
        int address[4];
        int mask = 0;

        /* At present, all known DNS blocking lists use A records, with
        IPv4 addresses on the RHS encoding the information they return. I
        wonder if this will linger on as the last vestige of IPv4 when IPv6
        is ubiquitous? Anyway, for now we use paranoia code to completely
        ignore IPv6 addresses. The default mask is 0, which always matches.
        We change this only for IPv4 addresses in the list. */

        if (host_aton(da->address, address) == 1) mask = address[0];

        /* Scan the returned addresses, skipping any that are IPv6 */

        while ((res = string_nextinlist(&ptr, &ipsep, NULL, 0)))
          {
          if (host_aton(res, address) != 1) continue;
          if ((address[0] & mask) == address[0]) break;
          }
        }

      /* If either

         (a) An IP address in an any ('=') list matched, or
         (b) No IP address in an all ('==') list matched

      then we're done searching. */

      if (((match_type & MT_ALL) != 0) == (res == NULL)) break;
      }

    /* If da == NULL, either

       (a) No IP address in an any ('=') list matched, or
       (b) An IP address in an all ('==') list didn't match

    so behave as if the DNSBL lookup had not succeeded, i.e. the host is not on
    the list. */

    if ((match_type == MT_NOT || match_type == MT_ALL) != (da == NULL))
      {
      HDEBUG(D_dnsbl)
        {
        uschar *res = NULL;
        switch(match_type)
          {
          case 0:
	    res = US"was no match"; break;
          case MT_NOT:
	    res = US"was an exclude match"; break;
          case MT_ALL:
	    res = US"was an IP address that did not match"; break;
          case MT_NOT|MT_ALL:
	    res = US"were no IP addresses that did not match"; break;
          }
        debug_printf("=> but we are not accepting this block class because\n");
        debug_printf("=> there %s for %s%c%s\n",
          res,
          ((match_type & MT_ALL) == 0)? "" : "=",
          bitmask? '&' : '=', iplist);
        }
      return FAIL;
      }
    }

  /* Either there was no IP list, or the record matched, implying that the
  domain is on the list. We now want to find a corresponding TXT record. If an
  alternate domain is specified for the TXT record, call this function
  recursively to look that up; this has the side effect of re-checking that
  there is indeed an A record at the alternate domain. */

  if (domain_txt != domain)
    return one_check_dnsbl(domain_txt, domain_txt, keydomain, prepend, NULL,
      FALSE, match_type, defer_return);

  /* If there is no alternate domain, look up a TXT record in the main domain
  if it has not previously been cached. */

  if (!cb->text_set)
    {
    cb->text_set = TRUE;
    if (dns_basic_lookup(dnsa, query, T_TXT) == DNS_SUCCEED)
      for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
           rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
        if (rr->type == T_TXT)
	  {
	  int len = (rr->data)[0];
	  if (len > 511) len = 127;
	  store_pool = POOL_PERM;
	  cb->text = string_sprintf("%.*s", len, CUS (rr->data+1));
	  store_pool = old_pool;
	  break;
	  }
    }

  dnslist_value = addlist;
  dnslist_text = cb->text;
  return OK;
  }

/* There was a problem with the DNS lookup */

if (cb->rc != DNS_NOMATCH && cb->rc != DNS_NODATA)
  {
  log_write(L_dnslist_defer, LOG_MAIN,
    "DNS list lookup defer (probably timeout) for %s: %s", query,
    (defer_return == OK)?   US"assumed in list" :
    (defer_return == FAIL)? US"assumed not in list" :
                            US"returned DEFER");
  return defer_return;
  }

/* No entry was found in the DNS; continue for next domain */

HDEBUG(D_dnsbl)
  {
  debug_printf("DNS lookup for %s failed\n", query);
  debug_printf("=> that means %s is not listed at %s\n",
     keydomain, domain);
  }

return FAIL;
}




/*************************************************
*        Check host against DNS black lists      *
*************************************************/

/* This function runs checks against a list of DNS black lists, until one
matches. Each item on the list can be of the form

  domain=ip-address/key

The domain is the right-most domain that is used for the query, for example,
blackholes.mail-abuse.org. If the IP address is present, there is a match only
if the DNS lookup returns a matching IP address. Several addresses may be
given, comma-separated, for example: x.y.z=127.0.0.1,127.0.0.2.

If no key is given, what is looked up in the domain is the inverted IP address
of the current client host. If a key is given, it is used to construct the
domain for the lookup. For example:

  dsn.rfc-ignorant.org/$sender_address_domain

After finding a match in the DNS, the domain is placed in $dnslist_domain, and
then we check for a TXT record for an error message, and if found, save its
value in $dnslist_text. We also cache everything in a tree, to optimize
multiple lookups.

The TXT record is normally looked up in the same domain as the A record, but
when many lists are combined in a single DNS domain, this will not be a very
specific message. It is possible to specify a different domain for looking up
TXT records; this is given before the main domain, comma-separated. For
example:

  dnslists = http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \
             socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3

The caching ensures that only one lookup in dnsbl.sorbs.net is done.

Note: an address for testing RBL is 192.203.178.39
Note: an address for testing DUL is 192.203.178.4
Note: a domain for testing RFCI is example.tld.dsn.rfc-ignorant.org

Arguments:
  where        the acl type
  listptr      the domain/address/data list
  log_msgptr   log message on error

Returns:    OK      successful lookup (i.e. the address is on the list), or
                      lookup deferred after +include_unknown
            FAIL    name not found, or no data found for the given type, or
                      lookup deferred after +exclude_unknown (default)
            DEFER   lookup failure, if +defer_unknown was set
*/

int
verify_check_dnsbl(int where, const uschar ** listptr, uschar ** log_msgptr)
{
int sep = 0;
int defer_return = FAIL;
const uschar *list = *listptr;
uschar *domain;
uschar revadd[128];        /* Long enough for IPv6 address */

/* Indicate that the inverted IP address is not yet set up */

revadd[0] = 0;

/* In case this is the first time the DNS resolver is being used. */

dns_init(FALSE, FALSE, FALSE);	/*XXX dnssec? */

/* Loop through all the domains supplied, until something matches */

while ((domain = string_nextinlist(&list, &sep, NULL, 0)))
  {
  int rc;
  BOOL bitmask = FALSE;
  int match_type = 0;
  uschar *domain_txt;
  uschar *comma;
  uschar *iplist;
  uschar *key;

  HDEBUG(D_dnsbl) debug_printf("dnslists check: %s\n", domain);

  /* Deal with special values that change the behaviour on defer */

  if (domain[0] == '+')
    {
    if      (strcmpic(domain, US"+include_unknown") == 0) defer_return = OK;
    else if (strcmpic(domain, US"+exclude_unknown") == 0) defer_return = FAIL;
    else if (strcmpic(domain, US"+defer_unknown") == 0)   defer_return = DEFER;
    else
      log_write(0, LOG_MAIN|LOG_PANIC, "unknown item in dnslist (ignored): %s",
        domain);
    continue;
    }

  /* See if there's explicit data to be looked up */

  if ((key = Ustrchr(domain, '/'))) *key++ = 0;

  /* See if there's a list of addresses supplied after the domain name. This is
  introduced by an = or a & character; if preceded by = we require all matches
  and if preceded by ! we invert the result. */

  if (!(iplist = Ustrchr(domain, '=')))
    {
    bitmask = TRUE;
    iplist = Ustrchr(domain, '&');
    }

  if (iplist)				       /* Found either = or & */
    {
    if (iplist > domain && iplist[-1] == '!')  /* Handle preceding ! */
      {
      match_type |= MT_NOT;
      iplist[-1] = 0;
      }

    *iplist++ = 0;                             /* Terminate domain, move on */

    /* If we found = (bitmask == FALSE), check for == or =& */

    if (!bitmask && (*iplist == '=' || *iplist == '&'))
      {
      bitmask = *iplist++ == '&';
      match_type |= MT_ALL;
      }
    }


  /* If there is a comma in the domain, it indicates that a second domain for
  looking up TXT records is provided, before the main domain. Otherwise we must
  set domain_txt == domain. */

  domain_txt = domain;
  if ((comma = Ustrchr(domain, ',')))
    {
    *comma++ = 0;
    domain = comma;
    }

  /* Check that what we have left is a sensible domain name. There is no reason
  why these domains should in fact use the same syntax as hosts and email
  domains, but in practice they seem to. However, there is little point in
  actually causing an error here, because that would no doubt hold up incoming
  mail. Instead, I'll just log it. */

  for (uschar * s = domain; *s; s++)
    if (!isalnum(*s) && *s != '-' && *s != '.' && *s != '_')
      {
      log_write(0, LOG_MAIN, "dnslists domain \"%s\" contains "
        "strange characters - is this right?", domain);
      break;
      }

  /* Check the alternate domain if present */

  if (domain_txt != domain) for (uschar * s = domain_txt; *s; s++)
    if (!isalnum(*s) && *s != '-' && *s != '.' && *s != '_')
      {
      log_write(0, LOG_MAIN, "dnslists domain \"%s\" contains "
        "strange characters - is this right?", domain_txt);
      break;
      }

  /* If there is no key string, construct the query by adding the domain name
  onto the inverted host address, and perform a single DNS lookup. */

  if (!key)
    {
    if (where == ACL_WHERE_NOTSMTP_START || where == ACL_WHERE_NOTSMTP)
      {
      *log_msgptr = string_sprintf
	("cannot test auto-keyed dnslists condition in %s ACL",
	  acl_wherenames[where]);
      return ERROR;
      }
    if (!sender_host_address) return FAIL;    /* can never match */
    if (revadd[0] == 0) invert_address(revadd, sender_host_address);
    rc = one_check_dnsbl(domain, domain_txt, sender_host_address, revadd,
      iplist, bitmask, match_type, defer_return);
    if (rc == OK)
      {
      dnslist_domain = string_copy(domain_txt);
      dnslist_matched = string_copy(sender_host_address);
      HDEBUG(D_dnsbl) debug_printf("=> that means %s is listed at %s\n",
        sender_host_address, dnslist_domain);
      }
    if (rc != FAIL) return rc;     /* OK or DEFER */
    }

  /* If there is a key string, it can be a list of domains or IP addresses to
  be concatenated with the main domain. */

  else
    {
    int keysep = 0;
    BOOL defer = FALSE;
    uschar *keydomain;
    uschar keyrevadd[128];

    while ((keydomain = string_nextinlist(CUSS &key, &keysep, NULL, 0)))
      {
      uschar *prepend = keydomain;

      if (string_is_ip_address(keydomain, NULL) != 0)
        {
        invert_address(keyrevadd, keydomain);
        prepend = keyrevadd;
        }

      rc = one_check_dnsbl(domain, domain_txt, keydomain, prepend, iplist,
        bitmask, match_type, defer_return);
      if (rc == OK)
        {
        dnslist_domain = string_copy(domain_txt);
        dnslist_matched = string_copy(keydomain);
        HDEBUG(D_dnsbl) debug_printf("=> that means %s is listed at %s\n",
          keydomain, dnslist_domain);
        return OK;
        }

      /* If the lookup deferred, remember this fact. We keep trying the rest
      of the list to see if we get a useful result, and if we don't, we return
      DEFER at the end. */

      if (rc == DEFER) defer = TRUE;
      }    /* continue with next keystring domain/address */

    if (defer) return DEFER;
    }
  }        /* continue with next dnsdb outer domain */

return FAIL;
}

/* vi: aw ai sw=2
*/
/* End of verify.c */