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https://github.com/cuberite/libevent.git
synced 2025-09-09 04:19:10 -04:00
evdns_getaddrinfo() now supports the /etc/hosts file.
The regular blocking evutil_getaddrinfo() already supported /etc/hosts by falling back to getaddrinfo() or gethostbyname(). But evdns_getaddrinfo() had no such facility. Now it does. The data structure here isn't very clever. I guess people with huge /etc/hosts files will either need to get out of the 1980s, or submit a patch to this code so that it uses a hashtable instead of a linked list. Includes basic unit tests.
This commit is contained in:
Nick Mathewson
parent
0f7144fd8b
commit
72dd666777
280
evdns.c
280
evdns.c
@ -363,11 +363,24 @@ struct evdns_base {
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struct search_state *global_search_state;
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TAILQ_HEAD(hosts_list, hosts_entry) hostsdb;
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#ifndef _EVENT_DISABLE_THREAD_SUPPORT
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void *lock;
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#endif
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};
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struct hosts_entry {
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TAILQ_ENTRY(hosts_entry) next;
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union {
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struct sockaddr sa;
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struct sockaddr_in sin;
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struct sockaddr_in6 sin6;
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} addr;
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int addrlen;
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char hostname[1];
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};
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static struct evdns_base *current_base = NULL;
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struct evdns_base *
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@ -2502,6 +2515,28 @@ evdns_nameserver_add(unsigned long int address) {
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return evdns_base_nameserver_add(current_base, address);
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}
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static void
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sockaddr_setport(struct sockaddr *sa, ev_uint16_t port)
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{
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if (sa->sa_family == AF_INET) {
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((struct sockaddr_in *)sa)->sin_port = htons(port);
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} else if (sa->sa_family == AF_INET6) {
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((struct sockaddr_in6 *)sa)->sin6_port = htons(port);
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}
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}
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static ev_uint16_t
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sockaddr_getport(struct sockaddr *sa)
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{
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if (sa->sa_family == AF_INET) {
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return ntohs(((struct sockaddr_in *)sa)->sin_port);
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} else if (sa->sa_family == AF_INET6) {
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return ntohs(((struct sockaddr_in6 *)sa)->sin6_port);
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} else {
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return 0;
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}
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}
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/* exported function */
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int
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evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) {
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@ -2516,20 +2551,8 @@ evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string)
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return 4;
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}
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sa = (struct sockaddr *) &ss;
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if (sa->sa_family == AF_INET) {
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struct sockaddr_in *sin = (struct sockaddr_in *)sa;
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if (sin->sin_port == 0)
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sin->sin_port = htons(53);
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}
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#ifdef AF_INET6
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else if (sa->sa_family == AF_INET6) {
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struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;
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if (sin6->sin6_port == 0)
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sin6->sin6_port = htons(53);
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}
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#endif
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else
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return -1;
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if (sockaddr_getport(sa) == 0)
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sockaddr_setport(sa, 53);
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EVDNS_LOCK(base);
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res = _evdns_nameserver_add_impl(base, sa, len);
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@ -3370,42 +3393,32 @@ evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *con
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static int
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evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) {
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struct stat st;
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int fd, n, r;
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u8 *resolv;
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size_t n;
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char *resolv;
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char *start;
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int err = 0;
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log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
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fd = open(filename, O_RDONLY);
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if (fd < 0) {
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evdns_resolv_set_defaults(base, flags);
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return 1;
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if (flags & DNS_OPTION_HOSTSFILE) {
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#ifdef WIN32
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evdns_base_load_hosts(base, NULL);
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#else
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evdns_base_load_hosts(base, "/etc/hosts");
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#endif
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}
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if (fstat(fd, &st)) { err = 2; goto out1; }
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if (!st.st_size) {
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evdns_resolv_set_defaults(base, flags);
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err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0;
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goto out1;
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if ((err = evutil_read_file(filename, &resolv, &n, 0)) < 0) {
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if (err == -1) {
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/* No file. */
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evdns_resolv_set_defaults(base, flags);
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return 1;
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} else {
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return 2;
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}
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}
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if (st.st_size > 65535) { err = 3; goto out1; } /* no resolv.conf should be any bigger */
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resolv = (u8 *) mm_malloc((size_t)st.st_size + 1);
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if (!resolv) { err = 4; goto out1; }
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n = 0;
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while ((r = read(fd, resolv+n, (size_t)st.st_size-n)) > 0) {
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n += r;
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if (n == st.st_size)
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break;
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EVUTIL_ASSERT(n < st.st_size);
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}
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if (r < 0) { err = 5; goto out2; }
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resolv[n] = 0; /* we malloced an extra byte; this should be fine. */
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start = (char *) resolv;
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start = resolv;
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for (;;) {
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char *const newline = strchr(start, '\n');
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if (!newline) {
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@ -3427,10 +3440,7 @@ evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char
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search_set_from_hostname(base);
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}
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out2:
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mm_free(resolv);
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out1:
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close(fd);
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return err;
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}
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@ -3441,6 +3451,8 @@ evdns_resolv_conf_parse(int flags, const char *const filename) {
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return evdns_base_resolv_conf_parse(current_base, flags, filename);
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}
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#ifdef WIN32
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/* Add multiple nameservers from a space-or-comma-separated list. */
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static int
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@ -3703,6 +3715,8 @@ evdns_base_new(struct event_base *event_base, int initialize_nameservers)
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base->global_nameserver_probe_initial_timeout.tv_sec = 10;
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base->global_nameserver_probe_initial_timeout.tv_usec = 0;
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TAILQ_INIT(&base->hostsdb);
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if (initialize_nameservers) {
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int r;
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#ifdef WIN32
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@ -3798,6 +3812,15 @@ evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests)
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mm_free(base->global_search_state);
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base->global_search_state = NULL;
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}
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{
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struct hosts_entry *victim;
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while ((victim = TAILQ_FIRST(&base->hostsdb))) {
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TAILQ_REMOVE(&base->hostsdb, victim, next);
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mm_free(victim);
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}
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}
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EVDNS_UNLOCK(base);
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EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE);
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@ -3822,6 +3845,111 @@ evdns_shutdown(int fail_requests)
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evdns_log_fn = NULL;
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}
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static int
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evdns_base_parse_hosts_line(struct evdns_base *base, char *line)
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{
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char *strtok_state;
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static const char *const delims = " \t";
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char *const addr = strtok_r(line, delims, &strtok_state);
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char *hostname, *hash;
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struct sockaddr_storage ss;
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int socklen = sizeof(ss);
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ASSERT_LOCKED(base);
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#define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
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if (!addr || *addr == '#')
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return 0;
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memset(&ss, 0, sizeof(ss));
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if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0)
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return -1;
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if (socklen > sizeof(struct sockaddr_in6))
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return -1;
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if (sockaddr_getport((struct sockaddr*)&ss))
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return -1;
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while ((hostname = NEXT_TOKEN)) {
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struct hosts_entry *he;
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size_t namelen;
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if ((hash = strchr(hostname, '#'))) {
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if (hash == hostname)
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return 0;
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*hash = '\0';
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}
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namelen = strlen(hostname);
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he = mm_calloc(1, sizeof(struct hosts_entry)+namelen);
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if (!he)
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return -1;
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EVUTIL_ASSERT(socklen <= sizeof(he->addr));
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memcpy(&he->addr, &ss, socklen);
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memcpy(he->hostname, hostname, namelen+1);
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he->addrlen = socklen;
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TAILQ_INSERT_TAIL(&base->hostsdb, he, next);
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if (hash)
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return 0;
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}
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return 0;
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#undef NEXT_TOKEN
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}
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static int
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evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname)
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{
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char *str=NULL, *cp, *eol;
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size_t len;
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int err=0;
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ASSERT_LOCKED(base);
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if (hosts_fname == NULL ||
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(err = evutil_read_file(hosts_fname, &str, &len, 0)) < 0) {
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char tmp[64];
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strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp));
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evdns_base_parse_hosts_line(base, tmp);
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strlcpy(tmp, "::1 localhost", sizeof(tmp));
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evdns_base_parse_hosts_line(base, tmp);
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return err ? -1 : 0;
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}
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/* This will break early if there is a NUL in the hosts file.
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* Probably not a problem.*/
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cp = str;
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for (;;) {
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eol = strchr(cp, '\n');
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if (eol) {
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*eol = '\0';
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evdns_base_parse_hosts_line(base, cp);
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cp = eol+1;
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} else {
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evdns_base_parse_hosts_line(base, cp);
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break;
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}
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}
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mm_free(str);
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return 0;
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}
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int
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evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
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{
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int res;
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if (!base)
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base = current_base;
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EVDNS_LOCK(base);
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res = evdns_base_load_hosts_impl(base, hosts_fname);
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EVDNS_UNLOCK(base);
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return res;
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}
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/* A single request for a getaddrinfo, either v4 or v6. */
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struct getaddrinfo_subrequest {
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struct evdns_request *r;
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@ -4106,6 +4234,64 @@ evdns_getaddrinfo_gotresolve(int result, char type, int count,
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}
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}
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static struct hosts_entry *
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find_hosts_entry(struct evdns_base *base, const char *hostname,
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struct hosts_entry *find_after)
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{
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struct hosts_entry *e;
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if (find_after)
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e = TAILQ_NEXT(find_after, next);
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else
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e = TAILQ_FIRST(&base->hostsdb);
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for (; e; e = TAILQ_NEXT(e, next)) {
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if (!evutil_ascii_strcasecmp(e->hostname, hostname))
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return e;
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}
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return NULL;
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}
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static int
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evdns_getaddrinfo_fromhosts(struct evdns_base *base,
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const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port,
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struct evutil_addrinfo **res)
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{
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int n_found = 0;
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struct hosts_entry *e;
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struct evutil_addrinfo *ai=NULL;
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int f = hints->ai_family;
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EVDNS_LOCK(base);
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for (e = find_hosts_entry(base, nodename, NULL); e;
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e = find_hosts_entry(base, nodename, e)) {
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struct evutil_addrinfo *ai_new;
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++n_found;
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if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) ||
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(e->addr.sa.sa_family == AF_INET6 && f == PF_INET))
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continue;
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ai_new = evutil_new_addrinfo(&e->addr.sa, e->addrlen, hints);
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if (!ai_new) {
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n_found = 0;
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goto out;
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}
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sockaddr_setport(ai_new->ai_addr, port);
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ai = evutil_addrinfo_append(ai, ai_new);
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}
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EVDNS_UNLOCK(base);
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out:
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if (n_found) {
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/* Note that we return an empty answer if we found entries for
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* this hostname but none were of the right address type. */
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*res = ai;
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return 0;
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} else {
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if (ai)
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evutil_freeaddrinfo(ai);
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return -1;
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}
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}
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struct evdns_getaddrinfo_request *
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evdns_getaddrinfo(struct evdns_base *dns_base,
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const char *nodename, const char *servname,
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@ -4158,6 +4344,12 @@ evdns_getaddrinfo(struct evdns_base *dns_base,
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return NULL;
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}
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/* If there is an entry in the hosts file, we should give it now. */
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if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) {
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cb(0, res, arg);
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return NULL;
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}
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/* Okay, things are serious now. We're going to need to actually
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* launch a request.
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*/
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@ -201,7 +201,8 @@ extern "C" {
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#define DNS_OPTION_SEARCH 1
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#define DNS_OPTION_NAMESERVERS 2
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#define DNS_OPTION_MISC 4
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#define DNS_OPTIONS_ALL 7
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#define DNS_OPTION_HOSTSFILE 8
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#define DNS_OPTIONS_ALL 15
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/**
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* The callback that contains the results from a lookup.
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@ -431,7 +432,7 @@ int evdns_base_set_option(struct evdns_base *base, const char *option, const cha
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@param base the evdns_base to which to apply this operation
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@param flags any of DNS_OPTION_NAMESERVERS|DNS_OPTION_SEARCH|DNS_OPTION_MISC|
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DNS_OPTIONS_ALL
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DNS_OPTIONS_HOSTSFILE|DNS_OPTIONS_ALL
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@param filename the path to the resolv.conf file
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@return 0 if successful, or various positive error codes if an error
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occurred (see above)
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@ -439,6 +440,17 @@ int evdns_base_set_option(struct evdns_base *base, const char *option, const cha
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*/
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int evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename);
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/**
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Load an /etc/hosts-style file from 'hosts_fname' into 'base'.
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If hosts_fname is NULL, add minimal entries for localhost, and nothing
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else.
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Note that only evdns_getaddrinfo uses the /etc/hosts entries.
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Return 0 on success, negative on failure.
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*/
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int evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname);
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/**
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Obtain nameserver information using the Windows API.
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@ -616,7 +628,6 @@ struct evdns_getaddrinfo_request;
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* Limitations:
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*
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* - The AI_V4MAPPED and AI_ALL flags are not currently implemented.
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* - We don't look at the /etc/hosts file.
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* - For ai_socktype, we only handle SOCKTYPE_STREAM, SOCKTYPE_UDP, and 0.
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* - For ai_protocol, we only handle IPPROTO_TCP, IPPROTO_UDP, and 0.
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*/
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@ -1151,6 +1151,9 @@ test_getaddrinfo_async(void *arg)
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struct evdns_base *dns_base = evdns_base_new(data->base, 0);
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/* for localhost */
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evdns_base_load_hosts(dns_base, NULL);
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memset(a_out, 0, sizeof(a_out));
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n_gai_results_pending = 10000; /* don't think about exiting yet. */
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@ -1260,6 +1263,43 @@ test_getaddrinfo_async(void *arg)
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evutil_freeaddrinfo(local_outcome.ai);
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local_outcome.ai = NULL;
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/* 1g. We find localhost immediately. (pf_unspec) */
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memset(&hints, 0, sizeof(hints));
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memset(&local_outcome, 0, sizeof(local_outcome));
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hints.ai_family = PF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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r = evdns_getaddrinfo(dns_base, "LOCALHOST", "80",
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&hints, gai_cb, &local_outcome);
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tt_int_op(r,==,0);
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tt_int_op(local_outcome.err,==,0);
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tt_assert(local_outcome.ai);
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/* we should get a v4 address of 127.0.0.1 .... */
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a = ai_find_by_family(local_outcome.ai, PF_INET);
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tt_assert(a);
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test_ai_eq(a, "127.0.0.1:80", SOCK_STREAM, IPPROTO_TCP);
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/* ... and a v6 address of ::1 */
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a = ai_find_by_family(local_outcome.ai, PF_INET6);
|
||||
tt_assert(a);
|
||||
test_ai_eq(a, "[::1]:80", SOCK_STREAM, IPPROTO_TCP);
|
||||
evutil_freeaddrinfo(local_outcome.ai);
|
||||
local_outcome.ai = NULL;
|
||||
|
||||
/* 1g. We find localhost immediately. (pf_inet6) */
|
||||
memset(&hints, 0, sizeof(hints));
|
||||
memset(&local_outcome, 0, sizeof(local_outcome));
|
||||
hints.ai_family = PF_INET6;
|
||||
hints.ai_socktype = SOCK_STREAM;
|
||||
r = evdns_getaddrinfo(dns_base, "LOCALHOST", "9999",
|
||||
&hints, gai_cb, &local_outcome);
|
||||
tt_int_op(r,==,0);
|
||||
tt_int_op(local_outcome.err,==,0);
|
||||
tt_assert(local_outcome.ai);
|
||||
a = local_outcome.ai;
|
||||
test_ai_eq(a, "[::1]:9999", SOCK_STREAM, IPPROTO_TCP);
|
||||
tt_ptr_op(a->ai_next, ==, NULL);
|
||||
evutil_freeaddrinfo(local_outcome.ai);
|
||||
local_outcome.ai = NULL;
|
||||
|
||||
/* 2. Okay, now we can actually test the asynchronous resolver. */
|
||||
/* Start a dummy local dns server... */
|
||||
port = get_generic_server(data->base, &dns_port,
|
||||
|
||||
Loading…
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Reference in New Issue
Block a user