| /* Copyright 1998 by the Massachusetts Institute of Technology. |
| * |
| * Permission to use, copy, modify, and distribute this |
| * software and its documentation for any purpose and without |
| * fee is hereby granted, provided that the above copyright |
| * notice appear in all copies and that both that copyright |
| * notice and this permission notice appear in supporting |
| * documentation, and that the name of M.I.T. not be used in |
| * advertising or publicity pertaining to distribution of the |
| * software without specific, written prior permission. |
| * M.I.T. makes no representations about the suitability of |
| * this software for any purpose. It is provided "as is" |
| * without express or implied warranty. |
| */ |
| |
| #include "setup.h" |
| #include <sys/types.h> |
| |
| #if defined(WIN32) && !defined(WATT32) |
| #include "nameser.h" |
| #else |
| #include <sys/socket.h> |
| #include <netinet/in.h> |
| #include <arpa/inet.h> |
| #include <netdb.h> |
| #include <arpa/nameser.h> |
| #endif |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <ctype.h> |
| |
| #include "ares.h" |
| #include "ares_private.h" |
| |
| #ifdef WATT32 |
| #undef WIN32 |
| #endif |
| |
| struct host_query { |
| /* Arguments passed to ares_gethostbyname() */ |
| ares_channel channel; |
| char *name; |
| ares_host_callback callback; |
| void *arg; |
| |
| const char *remaining_lookups; |
| }; |
| |
| static void next_lookup(struct host_query *hquery); |
| static void host_callback(void *arg, int status, unsigned char *abuf, |
| int alen); |
| static void end_hquery(struct host_query *hquery, int status, |
| struct hostent *host); |
| static int fake_hostent(const char *name, ares_host_callback callback, |
| void *arg); |
| static int file_lookup(const char *name, struct hostent **host); |
| static void sort_addresses(struct hostent *host, struct apattern *sortlist, |
| int nsort); |
| static int get_address_index(struct in_addr *addr, struct apattern *sortlist, |
| int nsort); |
| |
| void ares_gethostbyname(ares_channel channel, const char *name, int family, |
| ares_host_callback callback, void *arg) |
| { |
| struct host_query *hquery; |
| |
| /* Right now we only know how to look up Internet addresses. */ |
| if (family != AF_INET) |
| { |
| callback(arg, ARES_ENOTIMP, NULL); |
| return; |
| } |
| |
| if (fake_hostent(name, callback, arg)) |
| return; |
| |
| /* Allocate and fill in the host query structure. */ |
| hquery = malloc(sizeof(struct host_query)); |
| if (!hquery) |
| { |
| callback(arg, ARES_ENOMEM, NULL); |
| return; |
| } |
| hquery->channel = channel; |
| hquery->name = strdup(name); |
| if (!hquery->name) |
| { |
| free(hquery); |
| callback(arg, ARES_ENOMEM, NULL); |
| return; |
| } |
| hquery->callback = callback; |
| hquery->arg = arg; |
| hquery->remaining_lookups = channel->lookups; |
| |
| /* Start performing lookups according to channel->lookups. */ |
| next_lookup(hquery); |
| } |
| |
| static void next_lookup(struct host_query *hquery) |
| { |
| int status; |
| const char *p; |
| struct hostent *host; |
| |
| for (p = hquery->remaining_lookups; *p; p++) |
| { |
| switch (*p) |
| { |
| case 'b': |
| /* DNS lookup */ |
| hquery->remaining_lookups = p + 1; |
| ares_search(hquery->channel, hquery->name, C_IN, T_A, host_callback, |
| hquery); |
| return; |
| |
| case 'f': |
| /* Host file lookup */ |
| status = file_lookup(hquery->name, &host); |
| if (status != ARES_ENOTFOUND) |
| { |
| end_hquery(hquery, status, host); |
| return; |
| } |
| break; |
| } |
| } |
| end_hquery(hquery, ARES_ENOTFOUND, NULL); |
| } |
| |
| static void host_callback(void *arg, int status, unsigned char *abuf, int alen) |
| { |
| struct host_query *hquery = (struct host_query *) arg; |
| ares_channel channel = hquery->channel; |
| struct hostent *host; |
| |
| if (status == ARES_SUCCESS) |
| { |
| status = ares_parse_a_reply(abuf, alen, &host); |
| if (host && channel->nsort) |
| sort_addresses(host, channel->sortlist, channel->nsort); |
| end_hquery(hquery, status, host); |
| } |
| else if (status == ARES_EDESTRUCTION) |
| end_hquery(hquery, status, NULL); |
| else |
| next_lookup(hquery); |
| } |
| |
| static void end_hquery(struct host_query *hquery, int status, |
| struct hostent *host) |
| { |
| hquery->callback(hquery->arg, status, host); |
| if (host) |
| ares_free_hostent(host); |
| free(hquery->name); |
| free(hquery); |
| } |
| |
| /* If the name looks like an IP address, fake up a host entry, end the |
| * query immediately, and return true. Otherwise return false. |
| */ |
| static int fake_hostent(const char *name, ares_host_callback callback, |
| void *arg) |
| { |
| struct in_addr addr; |
| struct hostent hostent; |
| const char *p; |
| char *aliases[1] = { NULL }; |
| char *addrs[2]; |
| |
| /* It only looks like an IP address if it's all numbers and dots. */ |
| for (p = name; *p; p++) |
| { |
| if (!isdigit((unsigned char)*p) && *p != '.') |
| return 0; |
| } |
| |
| /* It also only looks like an IP address if it's non-zero-length and |
| * doesn't end with a dot. |
| */ |
| if (p == name || *(p - 1) == '.') |
| return 0; |
| |
| /* It looks like an IP address. Figure out what IP address it is. */ |
| addr.s_addr = inet_addr(name); |
| if (addr.s_addr == INADDR_NONE) |
| { |
| callback(arg, ARES_EBADNAME, NULL); |
| return 1; |
| } |
| |
| /* Duplicate the name, to avoid a constness violation. */ |
| hostent.h_name = strdup(name); |
| if (!hostent.h_name) |
| { |
| callback(arg, ARES_ENOMEM, NULL); |
| return 1; |
| } |
| |
| /* Fill in the rest of the host structure and terminate the query. */ |
| addrs[0] = (char *) &addr; |
| addrs[1] = NULL; |
| hostent.h_aliases = aliases; |
| hostent.h_addrtype = AF_INET; |
| hostent.h_length = sizeof(struct in_addr); |
| hostent.h_addr_list = addrs; |
| callback(arg, ARES_SUCCESS, &hostent); |
| |
| free(hostent.h_name); |
| return 1; |
| } |
| |
| static int file_lookup(const char *name, struct hostent **host) |
| { |
| FILE *fp; |
| char **alias; |
| int status; |
| |
| #ifdef WIN32 |
| char PATH_HOSTS[MAX_PATH]; |
| if (IS_NT()) { |
| char tmp[MAX_PATH]; |
| HKEY hkeyHosts; |
| |
| if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ, &hkeyHosts) |
| == ERROR_SUCCESS) |
| { |
| DWORD dwLength = MAX_PATH; |
| RegQueryValueEx(hkeyHosts, DATABASEPATH, NULL, NULL, tmp, |
| &dwLength); |
| ExpandEnvironmentStrings(tmp, PATH_HOSTS, MAX_PATH); |
| RegCloseKey(hkeyHosts); |
| } |
| } |
| else |
| GetWindowsDirectory(PATH_HOSTS, MAX_PATH); |
| |
| strcat(PATH_HOSTS, WIN_PATH_HOSTS); |
| |
| #elif defined(WATT32) |
| extern const char *_w32_GetHostsFile (void); |
| const char *PATH_HOSTS = _w32_GetHostsFile(); |
| |
| if (!PATH_HOSTS) |
| return ARES_ENOTFOUND; |
| #endif |
| |
| fp = fopen(PATH_HOSTS, "r"); |
| if (!fp) |
| return ARES_ENOTFOUND; |
| |
| while ((status = ares__get_hostent(fp, host)) == ARES_SUCCESS) |
| { |
| if (strcasecmp((*host)->h_name, name) == 0) |
| break; |
| for (alias = (*host)->h_aliases; *alias; alias++) |
| { |
| if (strcasecmp(*alias, name) == 0) |
| break; |
| } |
| if (*alias) |
| break; |
| ares_free_hostent(*host); |
| } |
| fclose(fp); |
| if (status == ARES_EOF) |
| status = ARES_ENOTFOUND; |
| if (status != ARES_SUCCESS) |
| *host = NULL; |
| return status; |
| } |
| |
| static void sort_addresses(struct hostent *host, struct apattern *sortlist, |
| int nsort) |
| { |
| struct in_addr a1, a2; |
| int i1, i2, ind1, ind2; |
| |
| /* This is a simple insertion sort, not optimized at all. i1 walks |
| * through the address list, with the loop invariant that everything |
| * to the left of i1 is sorted. In the loop body, the value at i1 is moved |
| * back through the list (via i2) until it is in sorted order. |
| */ |
| for (i1 = 0; host->h_addr_list[i1]; i1++) |
| { |
| memcpy(&a1, host->h_addr_list[i1], sizeof(struct in_addr)); |
| ind1 = get_address_index(&a1, sortlist, nsort); |
| for (i2 = i1 - 1; i2 >= 0; i2--) |
| { |
| memcpy(&a2, host->h_addr_list[i2], sizeof(struct in_addr)); |
| ind2 = get_address_index(&a2, sortlist, nsort); |
| if (ind2 <= ind1) |
| break; |
| memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct in_addr)); |
| } |
| memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct in_addr)); |
| } |
| } |
| |
| /* Find the first entry in sortlist which matches addr. Return nsort |
| * if none of them match. |
| */ |
| static int get_address_index(struct in_addr *addr, struct apattern *sortlist, |
| int nsort) |
| { |
| int i; |
| |
| for (i = 0; i < nsort; i++) |
| { |
| if ((addr->s_addr & sortlist[i].mask.s_addr) == sortlist[i].addr.s_addr) |
| break; |
| } |
| return i; |
| } |