/* Host name resolution and matching. Copyright (C) 1995, 1996, 1997, 2000, 2001 Free Software Foundation, Inc. This file is part of GNU Wget. GNU Wget is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. GNU Wget is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Wget; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. In addition, as a special exception, the Free Software Foundation gives permission to link the code of its release of Wget with the OpenSSL project's "OpenSSL" library (or with modified versions of it that use the same license as the "OpenSSL" library), and distribute the linked executables. You must obey the GNU General Public License in all respects for all of the code used other than "OpenSSL". If you modify this file, you may extend this exception to your version of the file, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ #include #ifndef WINDOWS #include #endif #include #include #ifdef HAVE_STRING_H # include #else # include #endif #include #include #ifndef WINDOWS # include # include # ifndef __BEOS__ # include # endif # include # define SET_H_ERRNO(err) ((void)(h_errno = (err))) #else /* WINDOWS */ # define SET_H_ERRNO(err) WSASetLastError (err) #endif /* WINDOWS */ #include #include "wget.h" #include "utils.h" #include "host.h" #include "url.h" #include "hash.h" #include "connect.h" /* for socket_has_inet6 */ #ifndef errno extern int errno; #endif #ifndef h_errno # ifndef __CYGWIN__ extern int h_errno; # endif #endif #ifndef NO_ADDRESS # define NO_ADDRESS NO_DATA #endif /* Lists of IP addresses that result from running DNS queries. See lookup_host for details. */ struct address_list { int count; /* number of adrresses */ ip_address *addresses; /* pointer to the string of addresses */ int faulty; /* number of addresses known not to work. */ int connected; /* whether we were able to connect to one of the addresses in the list, at least once. */ int refcount; /* reference count; when it drops to 0, the entry is freed. */ }; /* Get the bounds of the address list. */ void address_list_get_bounds (const struct address_list *al, int *start, int *end) { *start = al->faulty; *end = al->count; } /* Return a pointer to the address at position POS. */ const ip_address * address_list_address_at (const struct address_list *al, int pos) { assert (pos >= al->faulty && pos < al->count); return al->addresses + pos; } /* Return non-zero if AL contains IP, zero otherwise. */ int address_list_contains (const struct address_list *al, const ip_address *ip) { int i; switch (ip->type) { case IPV4_ADDRESS: for (i = 0; i < al->count; i++) { ip_address *cur = al->addresses + i; if (cur->type == IPV4_ADDRESS && (ADDRESS_IPV4_IN_ADDR (cur).s_addr == ADDRESS_IPV4_IN_ADDR (ip).s_addr)) return 1; } return 0; #ifdef ENABLE_IPV6 case IPV6_ADDRESS: for (i = 0; i < al->count; i++) { ip_address *cur = al->addresses + i; if (cur->type == IPV6_ADDRESS #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID && ADDRESS_IPV6_SCOPE (cur) == ADDRESS_IPV6_SCOPE (ip) #endif && IN6_ARE_ADDR_EQUAL (&ADDRESS_IPV6_IN6_ADDR (cur), &ADDRESS_IPV6_IN6_ADDR (ip))) return 1; } return 0; #endif /* ENABLE_IPV6 */ default: abort (); } } /* Mark the INDEXth element of AL as faulty, so that the next time this address list is used, the faulty element will be skipped. */ void address_list_set_faulty (struct address_list *al, int index) { /* We assume that the address list is traversed in order, so that a "faulty" attempt is always preceded with all-faulty addresses, and this is how Wget uses it. */ assert (index == al->faulty); ++al->faulty; if (al->faulty >= al->count) /* All addresses have been proven faulty. Since there's not much sense in returning the user an empty address list the next time, we'll rather make them all clean, so that they can be retried anew. */ al->faulty = 0; } /* Set the "connected" flag to true. This flag used by connect.c to see if the host perhaps needs to be resolved again. */ void address_list_set_connected (struct address_list *al) { al->connected = 1; } /* Return the value of the "connected" flag. */ int address_list_connected_p (const struct address_list *al) { return al->connected; } #ifdef ENABLE_IPV6 /* Create an address_list from the addresses in the given struct addrinfo. */ static struct address_list * address_list_from_addrinfo (const struct addrinfo *ai) { struct address_list *al; const struct addrinfo *ptr; int cnt; ip_address *ip; cnt = 0; for (ptr = ai; ptr != NULL ; ptr = ptr->ai_next) if (ptr->ai_family == AF_INET || ptr->ai_family == AF_INET6) ++cnt; if (cnt == 0) return NULL; al = xnew0 (struct address_list); al->addresses = xnew_array (ip_address, cnt); al->count = cnt; al->refcount = 1; ip = al->addresses; for (ptr = ai; ptr != NULL; ptr = ptr->ai_next) if (ptr->ai_family == AF_INET6) { const struct sockaddr_in6 *sin6 = (const struct sockaddr_in6 *)ptr->ai_addr; ip->type = IPV6_ADDRESS; ADDRESS_IPV6_IN6_ADDR (ip) = sin6->sin6_addr; #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID ADDRESS_IPV6_SCOPE (ip) = sin6->sin6_scope_id; #endif ++ip; } else if (ptr->ai_family == AF_INET) { const struct sockaddr_in *sin = (const struct sockaddr_in *)ptr->ai_addr; ip->type = IPV4_ADDRESS; ADDRESS_IPV4_IN_ADDR (ip) = sin->sin_addr; ++ip; } assert (ip - al->addresses == cnt); return al; } #define IS_IPV4(addr) (((const ip_address *) addr)->type == IPV4_ADDRESS) /* Compare two IP addresses by type, giving preference to the IPv4 address (sorting it first). In other words, return -1 if ADDR1 is IPv4 and ADDR2 is IPv6, +1 if ADDR1 is IPv6 and ADDR2 is IPv4, and 0 otherwise. This is intended to be used as the comparator arg to a qsort-like sorting function, which is why it accepts generic pointers. */ static int cmp_prefer_ipv4 (const void *addr1, const void *addr2) { return !IS_IPV4 (addr1) - !IS_IPV4 (addr2); } #define IS_IPV6(addr) (((const ip_address *) addr)->type == IPV6_ADDRESS) /* Like the above, but give preference to the IPv6 address. */ static int cmp_prefer_ipv6 (const void *addr1, const void *addr2) { return !IS_IPV6 (addr1) - !IS_IPV6 (addr2); } #else /* not ENABLE_IPV6 */ /* Create an address_list from a NULL-terminated vector of IPv4 addresses. This kind of vector is returned by gethostbyname. */ static struct address_list * address_list_from_ipv4_addresses (char **vec) { int count, i; struct address_list *al = xnew0 (struct address_list); count = 0; while (vec[count]) ++count; assert (count > 0); al->addresses = xnew_array (ip_address, count); al->count = count; al->refcount = 1; for (i = 0; i < count; i++) { ip_address *ip = &al->addresses[i]; ip->type = IPV4_ADDRESS; memcpy (ADDRESS_IPV4_DATA (ip), vec[i], 4); } return al; } #endif /* not ENABLE_IPV6 */ static void address_list_delete (struct address_list *al) { xfree (al->addresses); xfree (al); } /* Mark the address list as being no longer in use. This will reduce its reference count which will cause the list to be freed when the count reaches 0. */ void address_list_release (struct address_list *al) { --al->refcount; DEBUGP (("Releasing 0x%0*lx (new refcount %d).\n", PTR_FORMAT (al), al->refcount)); if (al->refcount <= 0) { DEBUGP (("Deleting unused 0x%0*lx.\n", PTR_FORMAT (al))); address_list_delete (al); } } /* Versions of gethostbyname and getaddrinfo that support timeout. */ #ifndef ENABLE_IPV6 struct ghbnwt_context { const char *host_name; struct hostent *hptr; }; static void gethostbyname_with_timeout_callback (void *arg) { struct ghbnwt_context *ctx = (struct ghbnwt_context *)arg; ctx->hptr = gethostbyname (ctx->host_name); } /* Just like gethostbyname, except it times out after TIMEOUT seconds. In case of timeout, NULL is returned and errno is set to ETIMEDOUT. The function makes sure that when NULL is returned for reasons other than timeout, errno is reset. */ static struct hostent * gethostbyname_with_timeout (const char *host_name, double timeout) { struct ghbnwt_context ctx; ctx.host_name = host_name; if (run_with_timeout (timeout, gethostbyname_with_timeout_callback, &ctx)) { SET_H_ERRNO (HOST_NOT_FOUND); errno = ETIMEDOUT; return NULL; } if (!ctx.hptr) errno = 0; return ctx.hptr; } /* Print error messages for host errors. */ static char * host_errstr (int error) { /* Can't use switch since some of these constants can be equal, which makes the compiler complain about duplicate case values. */ if (error == HOST_NOT_FOUND || error == NO_RECOVERY || error == NO_DATA || error == NO_ADDRESS) return _("Unknown host"); else if (error == TRY_AGAIN) /* Message modeled after what gai_strerror returns in similar circumstances. */ return _("Temporary failure in name resolution"); else return _("Unknown error"); } #else /* ENABLE_IPV6 */ struct gaiwt_context { const char *node; const char *service; const struct addrinfo *hints; struct addrinfo **res; int exit_code; }; static void getaddrinfo_with_timeout_callback (void *arg) { struct gaiwt_context *ctx = (struct gaiwt_context *)arg; ctx->exit_code = getaddrinfo (ctx->node, ctx->service, ctx->hints, ctx->res); } /* Just like getaddrinfo, except it times out after TIMEOUT seconds. In case of timeout, the EAI_SYSTEM error code is returned and errno is set to ETIMEDOUT. */ static int getaddrinfo_with_timeout (const char *node, const char *service, const struct addrinfo *hints, struct addrinfo **res, double timeout) { struct gaiwt_context ctx; ctx.node = node; ctx.service = service; ctx.hints = hints; ctx.res = res; if (run_with_timeout (timeout, getaddrinfo_with_timeout_callback, &ctx)) { errno = ETIMEDOUT; return EAI_SYSTEM; } return ctx.exit_code; } #endif /* ENABLE_IPV6 */ /* Pretty-print ADDR. When compiled without IPv6, this is the same as inet_ntoa. With IPv6, it either prints an IPv6 address or an IPv4 address. */ const char * pretty_print_address (const ip_address *addr) { switch (addr->type) { case IPV4_ADDRESS: return inet_ntoa (ADDRESS_IPV4_IN_ADDR (addr)); #ifdef ENABLE_IPV6 case IPV6_ADDRESS: { static char buf[128]; inet_ntop (AF_INET6, &ADDRESS_IPV6_IN6_ADDR (addr), buf, sizeof (buf)); #if 0 #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID { /* append "%SCOPE_ID" for all ?non-global? addresses */ char *p = buf + strlen (buf); *p++ = '%'; number_to_string (p, ADDRESS_IPV6_SCOPE (addr)); } #endif #endif buf[sizeof (buf) - 1] = '\0'; return buf; } #endif } abort (); } /* The following two functions were adapted from glibc. */ static int is_valid_ipv4_address (const char *str, const char *end) { int saw_digit = 0; int octets = 0; int val = 0; while (str < end) { int ch = *str++; if (ch >= '0' && ch <= '9') { val = val * 10 + (ch - '0'); if (val > 255) return 0; if (saw_digit == 0) { if (++octets > 4) return 0; saw_digit = 1; } } else if (ch == '.' && saw_digit == 1) { if (octets == 4) return 0; val = 0; saw_digit = 0; } else return 0; } if (octets < 4) return 0; return 1; } int is_valid_ipv6_address (const char *str, const char *end) { /* Use lower-case for these to avoid clash with system headers. */ enum { ns_inaddrsz = 4, ns_in6addrsz = 16, ns_int16sz = 2 }; const char *curtok; int tp; const char *colonp; int saw_xdigit; unsigned int val; tp = 0; colonp = NULL; if (str == end) return 0; /* Leading :: requires some special handling. */ if (*str == ':') { ++str; if (str == end || *str != ':') return 0; } curtok = str; saw_xdigit = 0; val = 0; while (str < end) { int ch = *str++; /* if ch is a number, add it to val. */ if (ISXDIGIT (ch)) { val <<= 4; val |= XDIGIT_TO_NUM (ch); if (val > 0xffff) return 0; saw_xdigit = 1; continue; } /* if ch is a colon ... */ if (ch == ':') { curtok = str; if (saw_xdigit == 0) { if (colonp != NULL) return 0; colonp = str + tp; continue; } else if (str == end) return 0; if (tp > ns_in6addrsz - ns_int16sz) return 0; tp += ns_int16sz; saw_xdigit = 0; val = 0; continue; } /* if ch is a dot ... */ if (ch == '.' && (tp <= ns_in6addrsz - ns_inaddrsz) && is_valid_ipv4_address (curtok, end) == 1) { tp += ns_inaddrsz; saw_xdigit = 0; break; } return 0; } if (saw_xdigit == 1) { if (tp > ns_in6addrsz - ns_int16sz) return 0; tp += ns_int16sz; } if (colonp != NULL) { if (tp == ns_in6addrsz) return 0; tp = ns_in6addrsz; } if (tp != ns_in6addrsz) return 0; return 1; } /* Simple host cache, used by lookup_host to speed up resolving. The cache doesn't handle TTL because Wget is a fairly short-lived application. Refreshing is attempted when connect fails, though -- see connect_to_host. */ /* Mapping between known hosts and to lists of their addresses. */ static struct hash_table *host_name_addresses_map; /* Return the host's resolved addresses from the cache, if available. */ static struct address_list * cache_query (const char *host) { struct address_list *al; if (!host_name_addresses_map) return NULL; al = hash_table_get (host_name_addresses_map, host); if (al) { DEBUGP (("Found %s in host_name_addresses_map (%p)\n", host, al)); ++al->refcount; return al; } return NULL; } /* Cache the DNS lookup of HOST. Subsequent invocations of lookup_host will return the cached value. */ static void cache_store (const char *host, struct address_list *al) { if (!host_name_addresses_map) host_name_addresses_map = make_nocase_string_hash_table (0); ++al->refcount; hash_table_put (host_name_addresses_map, xstrdup_lower (host), al); #ifdef ENABLE_DEBUG if (opt.debug) { int i; debug_logprintf ("Caching %s =>", host); for (i = 0; i < al->count; i++) debug_logprintf (" %s", pretty_print_address (al->addresses + i)); debug_logprintf ("\n"); } #endif } /* Remove HOST from the DNS cache. Does nothing is HOST is not in the cache. */ static void cache_remove (const char *host) { struct address_list *al; if (!host_name_addresses_map) return; al = hash_table_get (host_name_addresses_map, host); if (al) { address_list_release (al); hash_table_remove (host_name_addresses_map, host); } } /* Look up HOST in DNS and return a list of IP addresses. This function caches its result so that, if the same host is passed the second time, the addresses are returned without DNS lookup. (Use LH_REFRESH to force lookup, or set opt.dns_cache to 0 to globally disable caching.) The order of the returned addresses is affected by the setting of opt.prefer_family: if it is set to prefer_ipv4, IPv4 addresses are placed at the beginning; if it is prefer_ipv6, IPv6 ones are placed at the beginning; otherwise, the order is left intact. The relative order of addresses with the same family is left undisturbed in either case. FLAGS can be a combination of: LH_SILENT - don't print the "resolving ... done" messages. LH_BIND - resolve addresses for use with bind, which under IPv6 means to use AI_PASSIVE flag to getaddrinfo. Passive lookups are not cached under IPv6. LH_REFRESH - if HOST is cached, remove the entry from the cache and resolve it anew. */ struct address_list * lookup_host (const char *host, int flags) { struct address_list *al; int silent = flags & LH_SILENT; int use_cache; int numeric_address = 0; double timeout = opt.dns_timeout; #ifndef ENABLE_IPV6 /* If we're not using getaddrinfo, first check if HOST specifies a numeric IPv4 address. Some implementations of gethostbyname (e.g. the Ultrix one and possibly Winsock) don't accept dotted-decimal IPv4 addresses. */ { uint32_t addr_ipv4 = (uint32_t)inet_addr (host); if (addr_ipv4 != (uint32_t) -1) { /* No need to cache host->addr relation, just return the address. */ char *vec[2]; vec[0] = (char *)&addr_ipv4; vec[1] = NULL; return address_list_from_ipv4_addresses (vec); } } #else /* ENABLE_IPV6 */ /* If we're using getaddrinfo, at least check whether the address is already numeric, in which case there is no need to print the "Resolving..." output. (This comes at no additional cost since the is_valid_ipv*_address are already required for url_parse.) */ { const char *end = host + strlen (host); if (is_valid_ipv4_address (host, end) || is_valid_ipv6_address (host, end)) numeric_address = 1; } #endif /* Cache is normally on, but can be turned off with --no-dns-cache. Don't cache passive lookups under IPv6. */ use_cache = opt.dns_cache; #ifdef ENABLE_IPV6 if ((flags & LH_BIND) || numeric_address) use_cache = 0; #endif /* Try to find the host in the cache so we don't need to talk to the resolver. If LH_REFRESH is requested, remove HOST from the cache instead. */ if (use_cache) { if (!(flags & LH_REFRESH)) { al = cache_query (host); if (al) return al; } else cache_remove (host); } /* No luck with the cache; resolve HOST. */ if (!silent && !numeric_address) logprintf (LOG_VERBOSE, _("Resolving %s... "), escnonprint (host)); #ifdef ENABLE_IPV6 { int err; struct addrinfo hints, *res; xzero (hints); hints.ai_socktype = SOCK_STREAM; if (opt.ipv4_only) hints.ai_family = AF_INET; else if (opt.ipv6_only) hints.ai_family = AF_INET6; else { hints.ai_family = AF_UNSPEC; #ifdef AI_ADDRCONFIG hints.ai_flags |= AI_ADDRCONFIG; #else /* On systems without AI_ADDRCONFIG, emulate it by manually checking whether the system supports IPv6 sockets. */ if (!socket_has_inet6 ()) hints.ai_family = AF_INET; #endif } if (flags & LH_BIND) hints.ai_flags |= AI_PASSIVE; #ifdef AI_NUMERICHOST if (numeric_address) { /* Where available, the AI_NUMERICHOST hint can prevent costly access to DNS servers. */ hints.ai_flags |= AI_NUMERICHOST; timeout = 0; /* no timeout needed when "resolving" numeric hosts -- avoid setting up signal handlers and such. */ } #endif err = getaddrinfo_with_timeout (host, NULL, &hints, &res, timeout); if (err != 0 || res == NULL) { if (!silent) logprintf (LOG_VERBOSE, _("failed: %s.\n"), err != EAI_SYSTEM ? gai_strerror (err) : strerror (errno)); return NULL; } al = address_list_from_addrinfo (res); freeaddrinfo (res); if (!al) { logprintf (LOG_VERBOSE, _("failed: No IPv4/IPv6 addresses for host.\n")); return NULL; } /* Reorder addresses so that IPv4 ones (or IPv6 ones, as per --prefer-family) come first. Sorting is stable so the order of the addresses with the same family is undisturbed. */ if (al->count > 1 && opt.prefer_family != prefer_none) stable_sort (al->addresses, al->count, sizeof (ip_address), opt.prefer_family == prefer_ipv4 ? cmp_prefer_ipv4 : cmp_prefer_ipv6); } #else /* not ENABLE_IPV6 */ { struct hostent *hptr = gethostbyname_with_timeout (host, timeout); if (!hptr) { if (!silent) { if (errno != ETIMEDOUT) logprintf (LOG_VERBOSE, _("failed: %s.\n"), host_errstr (h_errno)); else logputs (LOG_VERBOSE, _("failed: timed out.\n")); } return NULL; } /* Do older systems have h_addr_list? */ al = address_list_from_ipv4_addresses (hptr->h_addr_list); } #endif /* not ENABLE_IPV6 */ /* Print the addresses determined by DNS lookup, but no more than three. */ if (!silent && !numeric_address) { int i; int printmax = al->count <= 3 ? al->count : 3; for (i = 0; i < printmax; i++) { logprintf (LOG_VERBOSE, "%s", pretty_print_address (al->addresses + i)); if (i < printmax - 1) logputs (LOG_VERBOSE, ", "); } if (printmax != al->count) logputs (LOG_VERBOSE, ", ..."); logputs (LOG_VERBOSE, "\n"); } /* Cache the lookup information. */ if (use_cache) cache_store (host, al); return al; } /* Determine whether a URL is acceptable to be followed, according to a list of domains to accept. */ int accept_domain (struct url *u) { assert (u->host != NULL); if (opt.domains) { if (!sufmatch ((const char **)opt.domains, u->host)) return 0; } if (opt.exclude_domains) { if (sufmatch ((const char **)opt.exclude_domains, u->host)) return 0; } return 1; } /* Check whether WHAT is matched in LIST, each element of LIST being a pattern to match WHAT against, using backward matching (see match_backwards() in utils.c). If an element of LIST matched, 1 is returned, 0 otherwise. */ int sufmatch (const char **list, const char *what) { int i, j, k, lw; lw = strlen (what); for (i = 0; list[i]; i++) { for (j = strlen (list[i]), k = lw; j >= 0 && k >= 0; j--, k--) if (TOLOWER (list[i][j]) != TOLOWER (what[k])) break; /* The domain must be first to reach to beginning. */ if (j == -1) return 1; } return 0; } static int host_cleanup_mapper (void *key, void *value, void *arg_ignored) { struct address_list *al; xfree (key); /* host */ al = (struct address_list *)value; assert (al->refcount == 1); address_list_delete (al); return 0; } void host_cleanup (void) { if (host_name_addresses_map) { hash_table_map (host_name_addresses_map, host_cleanup_mapper, NULL); hash_table_destroy (host_name_addresses_map); host_name_addresses_map = NULL; } }