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diff --git a/addrtostr.c b/addrtostr.c
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+/*
+ * Copyright (c) 1999 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * 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. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the Kungliga Tekniska
+ * Högskolan and its contributors.
+ *
+ * 4. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+#include "addrtostr.h"
+
+#include <stdio.h>
+#include <string.h>
+
+/*
+ *
+ */
+
+#ifndef IN6ADDRSZ
+#define IN6ADDRSZ 16 /* IPv6 T_AAAA */
+#endif
+
+#ifndef INT16SZ
+#define INT16SZ 2 /* word size */
+#endif
+
+const char *
+addrtostr (const void *src, char *dst, size_t size)
+{
+ const u_char *srcaddr = (const u_char *)src;
+ const char digits[] = "0123456789";
+ int i;
+ const char *orig_dst = dst;
+
+ if (size < INET_ADDRSTRLEN) {
+ errno = ENOSPC;
+ return NULL;
+ }
+ for (i = 0; i < 4; ++i) {
+ int n = *srcaddr++;
+ int non_zerop = 0;
+
+ if (non_zerop || n / 100 > 0) {
+ *dst++ = digits[n / 100];
+ n %= 100;
+ non_zerop = 1;
+ }
+ if (non_zerop || n / 10 > 0) {
+ *dst++ = digits[n / 10];
+ n %= 10;
+ non_zerop = 1;
+ }
+ *dst++ = digits[n];
+ if (i != 3)
+ *dst++ = '.';
+ }
+ *dst++ = '\0';
+ return orig_dst;
+}
+
+/*
+ * Convert IPv6 binary address into presentation (printable) format.
+ */
+const char *
+addrtostr6 (const void *src, char *dst, size_t size)
+{
+ /*
+ * Note that int32_t and int16_t need only be "at least" large enough
+ * to contain a value of the specified size. On some systems, like
+ * Crays, there is no such thing as an integer variable with 16 bits.
+ * Keep this in mind if you think this function should have been coded
+ * to use pointer overlays. All the world's not a VAX.
+ */
+ const u_char *srcaddr = (const u_char *)src;
+ char *dp;
+ size_t space_left, added_space;
+ int snprintfed;
+ struct {
+ int base;
+ int len;
+ } best, cur;
+ uint16_t words [IN6ADDRSZ / INT16SZ];
+ int i;
+
+ /* Preprocess:
+ * Copy the input (bytewise) array into a wordwise array.
+ * Find the longest run of 0x00's in src[] for :: shorthanding.
+ */
+ for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
+ words[i] = (srcaddr[2*i] << 8) | srcaddr[2*i + 1];
+
+ best.len = 0;
+ best.base = -1;
+ cur.len = 0;
+ cur.base = -1;
+ for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
+ {
+ if (words[i] == 0)
+ {
+ if (cur.base == -1)
+ cur.base = i, cur.len = 1;
+ else cur.len++;
+ }
+ else if (cur.base != -1)
+ {
+ if (best.base == -1 || cur.len > best.len)
+ best = cur;
+ cur.base = -1;
+ }
+ }
+ if ((cur.base != -1) && (best.base == -1 || cur.len > best.len))
+ best = cur;
+ if (best.base != -1 && best.len < 2)
+ best.base = -1;
+
+ /* Format the result.
+ */
+ dp = dst;
+ space_left = size;
+#define APPEND_CHAR(c) \
+ { \
+ if (space_left == 0) { \
+ errno = ENOSPC; \
+ return (NULL); \
+ } \
+ *dp++ = c; \
+ space_left--; \
+ }
+ for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++)
+ {
+ /* Are we inside the best run of 0x00's?
+ */
+ if (best.base != -1 && i >= best.base && i < (best.base + best.len))
+ {
+ if (i == best.base)
+ APPEND_CHAR(':');
+ continue;
+ }
+
+ /* Are we following an initial run of 0x00s or any real hex?
+ */
+ if (i != 0)
+ APPEND_CHAR(':');
+
+ /* Is this address an encapsulated IPv4?
+ */
+ if (i == 6 && best.base == 0 &&
+ (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
+ {
+ if (!addrtostr(srcaddr+12, dp, space_left))
+ {
+ errno = ENOSPC;
+ return (NULL);
+ }
+ added_space = strlen(dp);
+ dp += added_space;
+ space_left -= added_space;
+ break;
+ }
+ snprintfed = snprintf (dp, space_left, "%x", words[i]);
+ if (snprintfed < 0)
+ return (NULL);
+ if ((size_t) snprintfed >= space_left)
+ {
+ errno = ENOSPC;
+ return (NULL);
+ }
+ dp += snprintfed;
+ space_left -= snprintfed;
+ }
+
+ /* Was it a trailing run of 0x00's?
+ */
+ if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
+ APPEND_CHAR(':');
+ APPEND_CHAR('\0');
+
+ return (dst);
+}