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+/*
+ * Copyright (c) 2016-2021, OARC, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#include "bpft.h"
+#include "iaddr.h"
+
+#include <ldns/ldns.h>
+
+void prepare_bpft(void)
+{
+ unsigned udp10_mbs, udp10_mbc, udp11_mbc; //udp11_mbs
+ text_list bpfl;
+ text_ptr text;
+ size_t len;
+ char* p;
+
+ /* Prepare the must-be-set and must-be-clear tests. */
+ udp10_mbs = udp10_mbc = udp11_mbc = 0U; // udp11_mbs
+ if ((dir_wanted & DIR_INITIATE) != 0) {
+ if ((dir_wanted & DIR_RESPONSE) == 0)
+ udp10_mbc |= UDP10_QR_MASK;
+ } else if ((dir_wanted & DIR_RESPONSE) != 0) {
+ udp10_mbs |= UDP10_QR_MASK;
+ }
+ if ((msg_wanted & MSG_UPDATE) != 0) {
+ if ((msg_wanted & (MSG_QUERY | MSG_NOTIFY)) == 0)
+ udp10_mbs |= (LDNS_PACKET_UPDATE << UDP10_OP_SHIFT);
+ } else if ((msg_wanted & MSG_NOTIFY) != 0) {
+ if ((msg_wanted & (MSG_QUERY | MSG_UPDATE)) == 0)
+ udp10_mbs |= (LDNS_PACKET_NOTIFY << UDP10_OP_SHIFT);
+ } else if ((msg_wanted & MSG_QUERY) != 0) {
+ udp10_mbc |= UDP10_OP_MASK;
+ }
+ if (err_wanted == ERR_NO) {
+ udp10_mbc |= UDP10_TC_MASK;
+ udp11_mbc |= UDP11_RC_MASK;
+ }
+
+ /*
+ * Model
+ * (vlan) and (transport)
+ * (vlan) and ((icmp) or (frags) or (dns))
+ * (vlan) and ((icmp) or (frags) or ((ports) and (hosts)))
+ * (vlan) and ((icmp) or (frags) or (((tcp) or (udp)) and (hosts)))
+ * [(vlan) and] ( [(icmp) or] [(frags) or] ( ( [(tcp) or] (udp) ) [and (hosts)] ) )
+ */
+
+ /* Make a BPF program to do early course kernel-level filtering. */
+ INIT_LIST(bpfl);
+ len = 0;
+ if (!EMPTY(vlans_excl))
+ len += text_add(&bpfl, "vlan and ("); /* vlan and ( transports ... */
+ else
+ len += text_add(&bpfl, "("); /* ( transports ... */
+ if (wanticmp) {
+ len += text_add(&bpfl, " ( ip proto 1 or ip proto 58 ) or");
+ }
+ if (wantfrags) {
+ len += text_add(&bpfl, " ( ip[6:2] & 0x1fff != 0 or ip6[6] = 44 ) or");
+ }
+ len += text_add(&bpfl, " ("); /* ( dns ... */
+ len += text_add(&bpfl, " ("); /* ( ports ... */
+ if (wanttcp) {
+ len += text_add(&bpfl, " ( tcp port %d ) or", dns_port);
+ /* tcp packets can be filtered by initiators/responders, but
+ * not mbs/mbc. */
+ }
+ len += text_add(&bpfl, " ( udp port %d and ( ip6 or ( ip", dns_port);
+
+ if (udp10_mbc != 0)
+ len += text_add(&bpfl, " and udp[10] & 0x%x = 0",
+ udp10_mbc);
+ if (udp10_mbs != 0)
+ len += text_add(&bpfl, " and udp[10] & 0x%x = 0x%x",
+ udp10_mbs, udp10_mbs);
+ if (udp11_mbc != 0)
+ len += text_add(&bpfl, " and udp[11] & 0x%x = 0",
+ udp11_mbc);
+ /* Dead code, udp11_mbs never set
+ if (udp11_mbs != 0)
+ len += text_add(&bpfl, " and udp[11] & 0x%x = 0x%x",
+ udp11_mbs, udp11_mbs);
+*/
+
+ if (err_wanted != ERR_NO) {
+ len += text_add(&bpfl, " and (");
+ if ((err_wanted & ERR_TRUNC) != 0) {
+ len += text_add(&bpfl, " udp[10] & 0x%x = 0x%x or", UDP10_TC_MASK, UDP10_TC_MASK);
+ }
+ len += text_add(&bpfl, " 0x%x << (udp[11] & 0xf) & 0x%x != 0 )", ERR_RCODE_BASE, err_wanted);
+ }
+
+ len += text_add(&bpfl, " )))"); /* ... udp 53 ) */
+ len += text_add(&bpfl, " )"); /* ... ports ) */
+ if (options.bpf_hosts_apply_all) {
+ len += text_add(&bpfl, " )"); /* ... dns ) */
+ len += text_add(&bpfl, " )"); /* ... transport ) */
+ }
+ if (!EMPTY(initiators) || !EMPTY(responders)) {
+ const char* or = "or", *lp = "(", *sep;
+ endpoint_ptr ep;
+
+ len += text_add(&bpfl, " and host");
+ sep = lp;
+ for (ep = HEAD(initiators);
+ ep != NULL;
+ ep = NEXT(ep, link)) {
+ len += text_add(&bpfl, " %s %s", sep, ia_str(ep->ia));
+ sep = or ;
+ }
+ for (ep = HEAD(responders);
+ ep != NULL;
+ ep = NEXT(ep, link)) {
+ len += text_add(&bpfl, " %s %s", sep, ia_str(ep->ia));
+ sep = or ;
+ }
+ len += text_add(&bpfl, " )");
+ }
+ if (!EMPTY(not_initiators) || !EMPTY(not_responders)) {
+ const char* or = "or", *lp = "(", *sep;
+ endpoint_ptr ep;
+
+ len += text_add(&bpfl, " and not host");
+ sep = lp;
+ for (ep = HEAD(not_initiators);
+ ep != NULL;
+ ep = NEXT(ep, link)) {
+ len += text_add(&bpfl, " %s %s", sep, ia_str(ep->ia));
+ sep = or ;
+ }
+ for (ep = HEAD(not_responders);
+ ep != NULL;
+ ep = NEXT(ep, link)) {
+ len += text_add(&bpfl, " %s %s", sep, ia_str(ep->ia));
+ sep = or ;
+ }
+ len += text_add(&bpfl, " )");
+ }
+ if (!options.bpf_hosts_apply_all) {
+ len += text_add(&bpfl, " )"); /* ... dns ) */
+ len += text_add(&bpfl, " )"); /* ... transport ) */
+ }
+ if (extra_bpf)
+ len += text_add(&bpfl, " and ( %s )", extra_bpf);
+
+ bpft = calloc(len + 1, sizeof(char));
+ assert(bpft != NULL);
+ p = bpft;
+ for (text = HEAD(bpfl); text != NULL; text = NEXT(text, link)) {
+ memcpy(p, text->text, text->len);
+ p += text->len;
+ }
+ text_free(&bpfl);
+ if (!EMPTY(vlans_incl)) {
+ char* bpft_vlan;
+
+ len = (2 * len) + 64; /* add enough for the extra in snprintf() below */
+ bpft_vlan = calloc(len, sizeof(char));
+ assert(bpft_vlan != NULL);
+
+ snprintf(bpft_vlan, len, "( %s ) or ( vlan and ( %s ) )", bpft, bpft);
+ free(bpft);
+ bpft = bpft_vlan;
+ }
+ if (dumptrace >= 1)
+ fprintf(stderr, "%s: \"%s\"\n", ProgramName, bpft);
+}
+
+size_t text_add(text_list* list, const char* fmt, ...)
+{
+ text_ptr text;
+ va_list ap;
+ int len;
+
+ text = calloc(1, sizeof *text);
+ assert(text != NULL);
+ INIT_LINK(text, link);
+ va_start(ap, fmt);
+ len = vasprintf(&text->text, fmt, ap);
+ assert(len >= 0);
+ va_end(ap);
+ text->len = len;
+ APPEND(*list, text, link);
+ return (text->len);
+}
+
+void text_free(text_list* list)
+{
+ text_ptr at, text;
+
+ for (at = HEAD(*list); at;) {
+ text = at;
+ at = NEXT(text, link);
+
+ UNLINK(*list, text, link);
+ free(text->text);
+ assert(text != (void*)-1);
+ free(text);
+ }
+}
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