/* Copyright (c) 1996 by Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. */ #if defined(LIBC_SCCS) && !defined(lint) static char rcsid[] = "$Id: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $"; #endif /* LIBC_SCCS and not lint */ #include #include #include #include #include #include #include #include #include #include "../conf/portability.h" #ifdef SPRINTF_CHAR # define SPRINTF(x) strlen(sprintf/**/x) #else # define SPRINTF(x) ((size_t)sprintf x) #endif /* * WARNING: Don't even consider trying to compile this on a system where * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX. */ static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size)); static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size)); /* char * * inet_ntop(af, src, dst, size) * convert a network format address to presentation format. * return: * pointer to presentation format address (`dst'), or NULL (see errno). * author: * Paul Vixie, 1996. */ const char * inet_ntop(af, src, dst, size) int af; const void *src; char *dst; size_t size; { switch (af) { case AF_INET: return (inet_ntop4(src, dst, size)); case AF_INET6: return (inet_ntop6(src, dst, size)); default: errno = EAFNOSUPPORT; return (NULL); } /* NOTREACHED */ } /* const char * * inet_ntop4(src, dst, size) * format an IPv4 address, more or less like inet_ntoa() * return: * `dst' (as a const) * notes: * (1) uses no statics * (2) takes a u_char* not an in_addr as input * author: * Paul Vixie, 1996. */ static const char * inet_ntop4(src, dst, size) const u_char *src; char *dst; size_t size; { static const char fmt[] = "%u.%u.%u.%u"; char tmp[sizeof "255.255.255.255"]; if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) { errno = ENOSPC; return (NULL); } strcpy(dst, tmp); return (dst); } /* const char * * inet_ntop6(src, dst, size) * convert IPv6 binary address into presentation (printable) format * author: * Paul Vixie, 1996. */ static const char * inet_ntop6(src, dst, size) const u_char *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. */ char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp; struct { int base, len; } best, cur; u_int 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. */ memset(words, '\0', sizeof words); for (i = 0; i < IN6ADDRSZ; i++) words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3)); best.base = -1; 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) { if (best.base == -1 || cur.len > best.len) best = cur; } if (best.base != -1 && best.len < 2) best.base = -1; /* * Format the result. */ tp = tmp; 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) *tp++ = ':'; continue; } /* Are we following an initial run of 0x00s or any real hex? */ if (i != 0) *tp++ = ':'; /* Is this address an encapsulated IPv4? */ if (i == 6 && best.base == 0 && (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) { if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) return (NULL); tp += strlen(tp); break; } tp += SPRINTF((tp, "%x", words[i])); } /* Was it a trailing run of 0x00's? */ if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) *tp++ = ':'; *tp++ = '\0'; /* * Check for overflow, copy, and we're done. */ if ((size_t)(tp - tmp) > size) { errno = ENOSPC; return (NULL); } strcpy(dst, tmp); return (dst); }