/* * * Connection Manager * * Copyright (C) 2007-2012 Intel Corporation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program 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 this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * */ #ifdef HAVE_CONFIG_H #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include "connman.h" #if __BYTE_ORDER == __LITTLE_ENDIAN struct domain_hdr { uint16_t id; uint8_t rd:1; uint8_t tc:1; uint8_t aa:1; uint8_t opcode:4; uint8_t qr:1; uint8_t rcode:4; uint8_t z:3; uint8_t ra:1; uint16_t qdcount; uint16_t ancount; uint16_t nscount; uint16_t arcount; } __attribute__ ((packed)); #elif __BYTE_ORDER == __BIG_ENDIAN struct domain_hdr { uint16_t id; uint8_t qr:1; uint8_t opcode:4; uint8_t aa:1; uint8_t tc:1; uint8_t rd:1; uint8_t ra:1; uint8_t z:3; uint8_t rcode:4; uint16_t qdcount; uint16_t ancount; uint16_t nscount; uint16_t arcount; } __attribute__ ((packed)); #else #error "Unknown byte order" #endif struct partial_reply { uint16_t len; uint16_t received; unsigned char buf[]; }; struct server_data { int index; GList *domains; char *server; struct sockaddr *server_addr; socklen_t server_addr_len; int protocol; GIOChannel *channel; guint watch; guint timeout; gboolean enabled; gboolean connected; struct partial_reply *incoming_reply; }; struct request_data { union { struct sockaddr_in6 __sin6; /* Only for the length */ struct sockaddr sa; }; socklen_t sa_len; int client_sk; int protocol; guint16 srcid; guint16 dstid; guint16 altid; guint timeout; guint watch; guint numserv; guint numresp; gpointer request; gsize request_len; gpointer name; gpointer resp; gsize resplen; struct listener_data *ifdata; gboolean append_domain; }; struct listener_data { int index; GIOChannel *udp_listener_channel; guint udp_listener_watch; GIOChannel *tcp_listener_channel; guint tcp_listener_watch; }; struct cache_data { time_t inserted; time_t valid_until; time_t cache_until; int timeout; uint16_t type; uint16_t answers; unsigned int data_len; unsigned char *data; /* contains DNS header + body */ }; struct cache_entry { char *key; int want_refresh; int hits; struct cache_data *ipv4; struct cache_data *ipv6; }; struct domain_question { uint16_t type; uint16_t class; } __attribute__ ((packed)); struct domain_rr { uint16_t type; uint16_t class; uint32_t ttl; uint16_t rdlen; } __attribute__ ((packed)); /* * We limit how long the cached DNS entry stays in the cache. * By default the TTL (time-to-live) of the DNS response is used * when setting the cache entry life time. The value is in seconds. */ #define MAX_CACHE_TTL (60 * 30) /* * Also limit the other end, cache at least for 30 seconds. */ #define MIN_CACHE_TTL (30) /* * We limit the cache size to some sane value so that cached data does * not occupy too much memory. Each cached entry occupies on average * about 100 bytes memory (depending on DNS name length). * Example: caching www.connman.net uses 97 bytes memory. * The value is the max amount of cached DNS responses (count). */ #define MAX_CACHE_SIZE 256 static int cache_size; static GHashTable *cache; static int cache_refcount; static GSList *server_list = NULL; static GSList *request_list = NULL; static GHashTable *listener_table = NULL; static time_t next_refresh; static guint16 get_id() { return random(); } static int protocol_offset(int protocol) { switch (protocol) { case IPPROTO_UDP: return 0; case IPPROTO_TCP: return 2; default: return -EINVAL; } } /* * There is a power and efficiency benefit to have entries * in our cache expire at the same time. To this extend, * we round down the cache valid time to common boundaries. */ static time_t round_down_ttl(time_t end_time, int ttl) { if (ttl < 15) return end_time; /* Less than 5 minutes, round to 10 second boundary */ if (ttl < 300) { end_time = end_time / 10; end_time = end_time * 10; } else { /* 5 or more minutes, round to 30 seconds */ end_time = end_time / 30; end_time = end_time * 30; } return end_time; } static struct request_data *find_request(guint16 id) { GSList *list; for (list = request_list; list; list = list->next) { struct request_data *req = list->data; if (req->dstid == id || req->altid == id) return req; } return NULL; } static struct server_data *find_server(int index, const char *server, int protocol) { GSList *list; DBG("index %d server %s proto %d", index, server, protocol); for (list = server_list; list; list = list->next) { struct server_data *data = list->data; if (index < 0 && data->index < 0 && g_str_equal(data->server, server) == TRUE && data->protocol == protocol) return data; if (index < 0 || data->index < 0 || data->server == NULL) continue; if (data->index == index && g_str_equal(data->server, server) == TRUE && data->protocol == protocol) return data; } return NULL; } /* we can keep using the same resolve's */ static GResolv *ipv4_resolve; static GResolv *ipv6_resolve; static void dummy_resolve_func(GResolvResultStatus status, char **results, gpointer user_data) { } /* * Refresh a DNS entry, but also age the hit count a bit */ static void refresh_dns_entry(struct cache_entry *entry, char *name) { int age = 1; if (ipv4_resolve == NULL) { ipv4_resolve = g_resolv_new(0); g_resolv_set_address_family(ipv4_resolve, AF_INET); g_resolv_add_nameserver(ipv4_resolve, "127.0.0.1", 53, 0); } if (ipv6_resolve == NULL) { ipv6_resolve = g_resolv_new(0); g_resolv_set_address_family(ipv6_resolve, AF_INET6); g_resolv_add_nameserver(ipv6_resolve, "127.0.0.1", 53, 0); } if (entry->ipv4 == NULL) { DBG("Refresing A record for %s", name); g_resolv_lookup_hostname(ipv4_resolve, name, dummy_resolve_func, NULL); age = 4; } if (entry->ipv6 == NULL) { DBG("Refresing AAAA record for %s", name); g_resolv_lookup_hostname(ipv6_resolve, name, dummy_resolve_func, NULL); age = 4; } entry->hits -= age; if (entry->hits < 0) entry->hits = 0; } static int dns_name_length(unsigned char *buf) { if ((buf[0] & NS_CMPRSFLGS) == NS_CMPRSFLGS) /* compressed name */ return 2; return strlen((char *)buf); } static void update_cached_ttl(unsigned char *buf, int len, int new_ttl) { unsigned char *c; uint32_t *i; uint16_t *w; int l; /* skip the header */ c = buf + 12; len -= 12; /* skip the query, which is a name and 2 16 bit words */ l = dns_name_length(c); c += l; len -= l; c += 4; len -= 4; /* now we get the answer records */ while (len > 0) { /* first a name */ l = dns_name_length(c); c += l; len -= l; if (len < 0) break; /* then type + class, 2 bytes each */ c += 4; len -= 4; if (len < 0) break; /* now the 4 byte TTL field */ i = (uint32_t *)c; *i = htonl(new_ttl); c += 4; len -= 4; if (len < 0) break; /* now the 2 byte rdlen field */ w = (uint16_t *)c; c += ntohs(*w) + 2; len -= ntohs(*w) + 2; } } static void send_cached_response(int sk, unsigned char *buf, int len, const struct sockaddr *to, socklen_t tolen, int protocol, int id, uint16_t answers, int ttl) { struct domain_hdr *hdr; unsigned char *ptr = buf; int err, offset, dns_len, adj_len = len - 2; /* * The cached packet contains always the TCP offset (two bytes) * so skip them for UDP. */ switch (protocol) { case IPPROTO_UDP: ptr += 2; len -= 2; dns_len = len; offset = 0; break; case IPPROTO_TCP: offset = 2; dns_len = ptr[0] * 256 + ptr[1]; break; default: return; } if (len < 12) return; hdr = (void *) (ptr + offset); hdr->id = id; hdr->qr = 1; hdr->rcode = 0; hdr->ancount = htons(answers); hdr->nscount = 0; hdr->arcount = 0; /* if this is a negative reply, we are authorative */ if (answers == 0) hdr->aa = 1; else update_cached_ttl((unsigned char *)hdr, adj_len, ttl); DBG("sk %d id 0x%04x answers %d ptr %p length %d dns %d", sk, hdr->id, answers, ptr, len, dns_len); err = sendto(sk, ptr, len, MSG_NOSIGNAL, to, tolen); if (err < 0) { connman_error("Cannot send cached DNS response: %s", strerror(errno)); return; } if (err != len || (dns_len != (len - 2) && protocol == IPPROTO_TCP) || (dns_len != len && protocol == IPPROTO_UDP)) DBG("Packet length mismatch, sent %d wanted %d dns %d", err, len, dns_len); } static void send_response(int sk, unsigned char *buf, int len, const struct sockaddr *to, socklen_t tolen, int protocol) { struct domain_hdr *hdr; int err, offset = protocol_offset(protocol); DBG("sk %d", sk); if (offset < 0) return; if (len < 12) return; hdr = (void *) (buf + offset); DBG("id 0x%04x qr %d opcode %d", hdr->id, hdr->qr, hdr->opcode); hdr->qr = 1; hdr->rcode = 2; hdr->ancount = 0; hdr->nscount = 0; hdr->arcount = 0; err = sendto(sk, buf, len, MSG_NOSIGNAL, to, tolen); if (err < 0) { connman_error("Failed to send DNS response to %d: %s", sk, strerror(errno)); return; } } static gboolean request_timeout(gpointer user_data) { struct request_data *req = user_data; struct listener_data *ifdata; DBG("id 0x%04x", req->srcid); if (req == NULL) return FALSE; ifdata = req->ifdata; request_list = g_slist_remove(request_list, req); req->numserv--; if (req->resplen > 0 && req->resp != NULL) { int sk, err; sk = g_io_channel_unix_get_fd(ifdata->udp_listener_channel); err = sendto(sk, req->resp, req->resplen, MSG_NOSIGNAL, &req->sa, req->sa_len); if (err < 0) return FALSE; } else if (req->request && req->numserv == 0) { struct domain_hdr *hdr; if (req->protocol == IPPROTO_TCP) { hdr = (void *) (req->request + 2); hdr->id = req->srcid; send_response(req->client_sk, req->request, req->request_len, NULL, 0, IPPROTO_TCP); } else if (req->protocol == IPPROTO_UDP) { int sk; hdr = (void *) (req->request); hdr->id = req->srcid; sk = g_io_channel_unix_get_fd( ifdata->udp_listener_channel); send_response(sk, req->request, req->request_len, &req->sa, req->sa_len, IPPROTO_UDP); } } g_free(req->resp); g_free(req); return FALSE; } static int append_query(unsigned char *buf, unsigned int size, const char *query, const char *domain) { unsigned char *ptr = buf; int len; DBG("query %s domain %s", query, domain); while (query != NULL) { const char *tmp; tmp = strchr(query, '.'); if (tmp == NULL) { len = strlen(query); if (len == 0) break; *ptr = len; memcpy(ptr + 1, query, len); ptr += len + 1; break; } *ptr = tmp - query; memcpy(ptr + 1, query, tmp - query); ptr += tmp - query + 1; query = tmp + 1; } while (domain != NULL) { const char *tmp; tmp = strchr(domain, '.'); if (tmp == NULL) { len = strlen(domain); if (len == 0) break; *ptr = len; memcpy(ptr + 1, domain, len); ptr += len + 1; break; } *ptr = tmp - domain; memcpy(ptr + 1, domain, tmp - domain); ptr += tmp - domain + 1; domain = tmp + 1; } *ptr++ = 0x00; return ptr - buf; } static gboolean cache_check_is_valid(struct cache_data *data, time_t current_time) { if (data == NULL) return FALSE; if (data->cache_until < current_time) return FALSE; return TRUE; } /* * remove stale cached entries so that they can be refreshed */ static void cache_enforce_validity(struct cache_entry *entry) { time_t current_time = time(NULL); if (cache_check_is_valid(entry->ipv4, current_time) == FALSE && entry->ipv4) { DBG("cache timeout \"%s\" type A", entry->key); g_free(entry->ipv4->data); g_free(entry->ipv4); entry->ipv4 = NULL; } if (cache_check_is_valid(entry->ipv6, current_time) == FALSE && entry->ipv6) { DBG("cache timeout \"%s\" type AAAA", entry->key); g_free(entry->ipv6->data); g_free(entry->ipv6); entry->ipv6 = NULL; } } static uint16_t cache_check_validity(char *question, uint16_t type, struct cache_entry *entry) { time_t current_time = time(NULL); int want_refresh = 0; /* * if we have a popular entry, we want a refresh instead of * total destruction of the entry. */ if (entry->hits > 2) want_refresh = 1; cache_enforce_validity(entry); switch (type) { case 1: /* IPv4 */ if (cache_check_is_valid(entry->ipv4, current_time) == FALSE) { DBG("cache %s \"%s\" type A", entry->ipv4 ? "timeout" : "entry missing", question); if (want_refresh) entry->want_refresh = 1; /* * We do not remove cache entry if there is still * valid IPv6 entry found in the cache. */ if (cache_check_is_valid(entry->ipv6, current_time) == FALSE && want_refresh == FALSE) { g_hash_table_remove(cache, question); type = 0; } } break; case 28: /* IPv6 */ if (cache_check_is_valid(entry->ipv6, current_time) == FALSE) { DBG("cache %s \"%s\" type AAAA", entry->ipv6 ? "timeout" : "entry missing", question); if (want_refresh) entry->want_refresh = 1; if (cache_check_is_valid(entry->ipv4, current_time) == FALSE && want_refresh == FALSE) { g_hash_table_remove(cache, question); type = 0; } } break; } return type; } static struct cache_entry *cache_check(gpointer request, int *qtype, int proto) { char *question; struct cache_entry *entry; struct domain_question *q; uint16_t type; int offset, proto_offset; if (request == NULL) return NULL; proto_offset = protocol_offset(proto); if (proto_offset < 0) return NULL; question = request + proto_offset + 12; offset = strlen(question) + 1; q = (void *) (question + offset); type = ntohs(q->type); /* We only cache either A (1) or AAAA (28) requests */ if (type != 1 && type != 28) return NULL; entry = g_hash_table_lookup(cache, question); if (entry == NULL) return NULL; type = cache_check_validity(question, type, entry); if (type == 0) return NULL; *qtype = type; return entry; } /* * Get a label/name from DNS resource record. The function decompresses the * label if necessary. The function does not convert the name to presentation * form. This means that the result string will contain label lengths instead * of dots between labels. We intentionally do not want to convert to dotted * format so that we can cache the wire format string directly. */ static int get_name(int counter, unsigned char *pkt, unsigned char *start, unsigned char *max, unsigned char *output, int output_max, int *output_len, unsigned char **end, char *name, int *name_len) { unsigned char *p; /* Limit recursion to 10 (this means up to 10 labels in domain name) */ if (counter > 10) return -EINVAL; p = start; while (*p) { if ((*p & NS_CMPRSFLGS) == NS_CMPRSFLGS) { uint16_t offset = (*p & 0x3F) * 256 + *(p + 1); if (offset >= max - pkt) return -ENOBUFS; if (*end == NULL) *end = p + 2; return get_name(counter + 1, pkt, pkt + offset, max, output, output_max, output_len, end, name, name_len); } else { unsigned label_len = *p; if (pkt + label_len > max) return -ENOBUFS; if (*output_len > output_max) return -ENOBUFS; /* * We need the original name in order to check * if this answer is the correct one. */ name[(*name_len)++] = label_len; memcpy(name + *name_len, p + 1, label_len + 1); *name_len += label_len; /* We compress the result */ output[0] = NS_CMPRSFLGS; output[1] = 0x0C; *output_len = 2; p += label_len + 1; if (*end == NULL) *end = p; if (p >= max) return -ENOBUFS; } } return 0; } static int parse_rr(unsigned char *buf, unsigned char *start, unsigned char *max, unsigned char *response, unsigned int *response_size, uint16_t *type, uint16_t *class, int *ttl, int *rdlen, unsigned char **end, char *name) { struct domain_rr *rr; int err, offset; int name_len = 0, output_len = 0, max_rsp = *response_size; err = get_name(0, buf, start, max, response, max_rsp, &output_len, end, name, &name_len); if (err < 0) return err; offset = output_len; if ((unsigned int) offset > *response_size) return -ENOBUFS; rr = (void *) (*end); if (rr == NULL) return -EINVAL; *type = ntohs(rr->type); *class = ntohs(rr->class); *ttl = ntohl(rr->ttl); *rdlen = ntohs(rr->rdlen); if (*ttl < 0) return -EINVAL; memcpy(response + offset, *end, sizeof(struct domain_rr)); offset += sizeof(struct domain_rr); *end += sizeof(struct domain_rr); if ((unsigned int) (offset + *rdlen) > *response_size) return -ENOBUFS; memcpy(response + offset, *end, *rdlen); *end += *rdlen; *response_size = offset + *rdlen; return 0; } static gboolean check_alias(GSList *aliases, char *name) { GSList *list; if (aliases != NULL) { for (list = aliases; list; list = list->next) { int len = strlen((char *)list->data); if (strncmp((char *)list->data, name, len) == 0) return TRUE; } } return FALSE; } static int parse_response(unsigned char *buf, int buflen, char *question, int qlen, uint16_t *type, uint16_t *class, int *ttl, unsigned char *response, unsigned int *response_len, uint16_t *answers) { struct domain_hdr *hdr = (void *) buf; struct domain_question *q; unsigned char *ptr; uint16_t qdcount = ntohs(hdr->qdcount); uint16_t ancount = ntohs(hdr->ancount); int err, i; uint16_t qtype, qclass; unsigned char *next = NULL; unsigned int maxlen = *response_len; GSList *aliases = NULL, *list; char name[NS_MAXDNAME + 1]; if (buflen < 12) return -EINVAL; DBG("qr %d qdcount %d", hdr->qr, qdcount); /* We currently only cache responses where question count is 1 */ if (hdr->qr != 1 || qdcount != 1) return -EINVAL; ptr = buf + sizeof(struct domain_hdr); strncpy(question, (char *) ptr, qlen); qlen = strlen(question); ptr += qlen + 1; /* skip \0 */ q = (void *) ptr; qtype = ntohs(q->type); /* We cache only A and AAAA records */ if (qtype != 1 && qtype != 28) return -ENOMSG; qclass = ntohs(q->class); ptr += 2 + 2; /* ptr points now to answers */ err = -ENOMSG; *response_len = 0; *answers = 0; /* * We have a bunch of answers (like A, AAAA, CNAME etc) to * A or AAAA question. We traverse the answers and parse the * resource records. Only A and AAAA records are cached, all * the other records in answers are skipped. */ for (i = 0; i < ancount; i++) { /* * Get one address at a time to this buffer. * The max size of the answer is * 2 (pointer) + 2 (type) + 2 (class) + * 4 (ttl) + 2 (rdlen) + addr (16 or 4) = 28 * for A or AAAA record. * For CNAME the size can be bigger. */ unsigned char rsp[NS_MAXCDNAME]; unsigned int rsp_len = sizeof(rsp) - 1; int ret, rdlen; memset(rsp, 0, sizeof(rsp)); ret = parse_rr(buf, ptr, buf + buflen, rsp, &rsp_len, type, class, ttl, &rdlen, &next, name); if (ret != 0) { err = ret; goto out; } /* * Now rsp contains compressed or uncompressed resource * record. Next we check if this record answers the question. * The name var contains the uncompressed label. * One tricky bit is the CNAME records as they alias * the name we might be interested in. */ /* * Go to next answer if the class is not the one we are * looking for. */ if (*class != qclass) { ptr = next; next = NULL; continue; } /* * Try to resolve aliases also, type is CNAME(5). * This is important as otherwise the aliased names would not * be cached at all as the cache would not contain the aliased * question. * * If any CNAME is found in DNS packet, then we cache the alias * IP address instead of the question (as the server * said that question has only an alias). * This means in practice that if e.g., ipv6.google.com is * queried, DNS server returns CNAME of that name which is * ipv6.l.google.com. We then cache the address of the CNAME * but return the question name to client. So the alias * status of the name is not saved in cache and thus not * returned to the client. We do not return DNS packets from * cache to client saying that ipv6.google.com is an alias to * ipv6.l.google.com but we return instead a DNS packet that * says ipv6.google.com has address xxx which is in fact the * address of ipv6.l.google.com. For caching purposes this * should not cause any issues. */ if (*type == 5 && strncmp(question, name, qlen) == 0) { /* * So now the alias answered the question. This is * not very useful from caching point of view as * the following A or AAAA records will not match the * question. We need to find the real A/AAAA record * of the alias and cache that. */ unsigned char *end = NULL; int name_len = 0, output_len; memset(rsp, 0, sizeof(rsp)); rsp_len = sizeof(rsp) - 1; /* * Alias is in rdata part of the message, * and next-rdlen points to it. So we need to get * the real name of the alias. */ ret = get_name(0, buf, next - rdlen, buf + buflen, rsp, rsp_len, &output_len, &end, name, &name_len); if (ret != 0) { /* just ignore the error at this point */ ptr = next; next = NULL; continue; } /* * We should now have the alias of the entry we might * want to cache. Just remember it for a while. * We check the alias list when we have parsed the * A or AAAA record. */ aliases = g_slist_prepend(aliases, g_strdup(name)); ptr = next; next = NULL; continue; } if (*type == qtype) { /* * We found correct type (A or AAAA) */ if (check_alias(aliases, name) == TRUE || (aliases == NULL && strncmp(question, name, qlen) == 0)) { /* * We found an alias or the name of the rr * matches the question. If so, we append * the compressed label to the cache. * The end result is a response buffer that * will contain one or more cached and * compressed resource records. */ if (*response_len + rsp_len > maxlen) { err = -ENOBUFS; goto out; } memcpy(response + *response_len, rsp, rsp_len); *response_len += rsp_len; (*answers)++; err = 0; } } ptr = next; next = NULL; } out: for (list = aliases; list; list = list->next) g_free(list->data); g_slist_free(aliases); return err; } struct cache_timeout { time_t current_time; int max_timeout; int try_harder; }; static gboolean cache_check_entry(gpointer key, gpointer value, gpointer user_data) { struct cache_timeout *data = user_data; struct cache_entry *entry = value; int max_timeout; /* Scale the number of hits by half as part of cache aging */ entry->hits /= 2; /* * If either IPv4 or IPv6 cached entry has expired, we * remove both from the cache. */ if (entry->ipv4 != NULL && entry->ipv4->timeout > 0) { max_timeout = entry->ipv4->cache_until; if (max_timeout > data->max_timeout) data->max_timeout = max_timeout; if (entry->ipv4->cache_until < data->current_time) return TRUE; } if (entry->ipv6 != NULL && entry->ipv6->timeout > 0) { max_timeout = entry->ipv6->cache_until; if (max_timeout > data->max_timeout) data->max_timeout = max_timeout; if (entry->ipv6->cache_until < data->current_time) return TRUE; } /* * if we're asked to try harder, also remove entries that have * few hits */ if (data->try_harder && entry->hits < 4) return TRUE; return FALSE; } static void cache_cleanup(void) { static int max_timeout; struct cache_timeout data; int count = 0; data.current_time = time(NULL); data.max_timeout = 0; data.try_harder = 0; /* * In the first pass, we only remove entries that have timed out. * We use a cache of the first time to expire to do this only * when it makes sense. */ if (max_timeout <= data.current_time) { count = g_hash_table_foreach_remove(cache, cache_check_entry, &data); } DBG("removed %d in the first pass", count); /* * In the second pass, if the first pass turned up blank, * we also expire entries with a low hit count, * while aging the hit count at the same time. */ data.try_harder = 1; if (count == 0) count = g_hash_table_foreach_remove(cache, cache_check_entry, &data); if (count == 0) /* * If we could not remove anything, then remember * what is the max timeout and do nothing if we * have not yet reached it. This will prevent * constant traversal of the cache if it is full. */ max_timeout = data.max_timeout; else max_timeout = 0; } static gboolean cache_invalidate_entry(gpointer key, gpointer value, gpointer user_data) { struct cache_entry *entry = value; /* first, delete any expired elements */ cache_enforce_validity(entry); /* if anything is not expired, mark the entry for refresh */ if (entry->hits > 0 && (entry->ipv4 || entry->ipv6)) entry->want_refresh = 1; /* delete the cached data */ if (entry->ipv4) { g_free(entry->ipv4->data); g_free(entry->ipv4); entry->ipv4 = NULL; } if (entry->ipv6) { g_free(entry->ipv6->data); g_free(entry->ipv6); entry->ipv6 = NULL; } /* keep the entry if we want it refreshed, delete it otherwise */ if (entry->want_refresh) return FALSE; else return TRUE; } /* * cache_invalidate is called from places where the DNS landscape * has changed, say because connections are added or we entered a VPN. * The logic is to wipe all cache data, but mark all non-expired * parts of the cache for refresh rather than deleting the whole cache. */ static void cache_invalidate(void) { DBG("Invalidating the DNS cache %p", cache); if (cache == NULL) return; g_hash_table_foreach_remove(cache, cache_invalidate_entry, NULL); } static void cache_refresh_entry(struct cache_entry *entry) { cache_enforce_validity(entry); if (entry->hits > 2 && entry->ipv4 == NULL) entry->want_refresh = 1; if (entry->hits > 2 && entry->ipv6 == NULL) entry->want_refresh = 1; if (entry->want_refresh) { char *c; char dns_name[NS_MAXDNAME + 1]; entry->want_refresh = 0; /* turn a DNS name into a hostname with dots */ strncpy(dns_name, entry->key, NS_MAXDNAME); c = dns_name; while (c && *c) { int jump; jump = *c; *c = '.'; c += jump + 1; } DBG("Refreshing %s\n", dns_name); /* then refresh the hostname */ refresh_dns_entry(entry, &dns_name[1]); } } static void cache_refresh_iterator(gpointer key, gpointer value, gpointer user_data) { struct cache_entry *entry = value; cache_refresh_entry(entry); } static void cache_refresh(void) { if (cache == NULL) return; g_hash_table_foreach(cache, cache_refresh_iterator, NULL); } static int reply_query_type(unsigned char *msg, int len) { unsigned char *c; uint16_t *w; int l; int type; /* skip the header */ c = msg + sizeof(struct domain_hdr); len -= sizeof(struct domain_hdr); if (len < 0) return 0; /* now the query, which is a name and 2 16 bit words */ l = dns_name_length(c) + 1; c += l; w = (uint16_t *) c; type = ntohs(*w); return type; } static int cache_update(struct server_data *srv, unsigned char *msg, unsigned int msg_len) { int offset = protocol_offset(srv->protocol); int err, qlen, ttl = 0; uint16_t answers = 0, type = 0, class = 0; struct domain_hdr *hdr = (void *)(msg + offset); struct domain_question *q; struct cache_entry *entry; struct cache_data *data; char question[NS_MAXDNAME + 1]; unsigned char response[NS_MAXDNAME + 1]; unsigned char *ptr; unsigned int rsplen; gboolean new_entry = TRUE; time_t current_time; if (cache_size >= MAX_CACHE_SIZE) { cache_cleanup(); if (cache_size >= MAX_CACHE_SIZE) return 0; } current_time = time(NULL); /* don't do a cache refresh more than twice a minute */ if (next_refresh < current_time) { cache_refresh(); next_refresh = current_time + 30; } if (offset < 0) return 0; DBG("offset %d hdr %p msg %p rcode %d", offset, hdr, msg, hdr->rcode); /* Continue only if response code is 0 (=ok) */ if (hdr->rcode != 0) return 0; rsplen = sizeof(response) - 1; question[sizeof(question) - 1] = '\0'; err = parse_response(msg + offset, msg_len - offset, question, sizeof(question) - 1, &type, &class, &ttl, response, &rsplen, &answers); /* * special case: if we do a ipv6 lookup and get no result * for a record that's already in our ipv4 cache.. we want * to cache the negative response. */ if ((err == -ENOMSG || err == -ENOBUFS) && reply_query_type(msg + offset, msg_len - offset) == 28) { entry = g_hash_table_lookup(cache, question); if (entry && entry->ipv4 && entry->ipv6 == NULL) { int cache_offset = 0; data = g_try_new(struct cache_data, 1); if (data == NULL) return -ENOMEM; data->inserted = entry->ipv4->inserted; data->type = type; data->answers = hdr->ancount; data->timeout = entry->ipv4->timeout; if (srv->protocol == IPPROTO_UDP) cache_offset = 2; data->data_len = msg_len + cache_offset; data->data = ptr = g_malloc(data->data_len); ptr[0] = (data->data_len - 2) / 256; ptr[1] = (data->data_len - 2) - ptr[0] * 256; if (srv->protocol == IPPROTO_UDP) ptr += 2; data->valid_until = entry->ipv4->valid_until; data->cache_until = entry->ipv4->cache_until; memcpy(ptr, msg, msg_len); entry->ipv6 = data; /* * we will get a "hit" when we serve the response * out of the cache */ entry->hits--; if (entry->hits < 0) entry->hits = 0; return 0; } } if (err < 0 || ttl == 0) return 0; qlen = strlen(question); /* * If the cache contains already data, check if the * type of the cached data is the same and do not add * to cache if data is already there. * This is needed so that we can cache both A and AAAA * records for the same name. */ entry = g_hash_table_lookup(cache, question); if (entry == NULL) { entry = g_try_new(struct cache_entry, 1); if (entry == NULL) return -ENOMEM; data = g_try_new(struct cache_data, 1); if (data == NULL) { g_free(entry); return -ENOMEM; } entry->key = g_strdup(question); entry->ipv4 = entry->ipv6 = NULL; entry->want_refresh = 0; entry->hits = 0; if (type == 1) entry->ipv4 = data; else entry->ipv6 = data; } else { if (type == 1 && entry->ipv4 != NULL) return 0; if (type == 28 && entry->ipv6 != NULL) return 0; data = g_try_new(struct cache_data, 1); if (data == NULL) return -ENOMEM; if (type == 1) entry->ipv4 = data; else entry->ipv6 = data; /* * compensate for the hit we'll get for serving * the response out of the cache */ entry->hits--; if (entry->hits < 0) entry->hits = 0; new_entry = FALSE; } if (ttl < MIN_CACHE_TTL) ttl = MIN_CACHE_TTL; data->inserted = current_time; data->type = type; data->answers = answers; data->timeout = ttl; /* * The "2" in start of the length is the TCP offset. We allocate it * here even for UDP packet because it simplifies the sending * of cached packet. */ data->data_len = 2 + 12 + qlen + 1 + 2 + 2 + rsplen; data->data = ptr = g_malloc(data->data_len); data->valid_until = current_time + ttl; /* * Restrict the cached DNS record TTL to some sane value * in order to prevent data staying in the cache too long. */ if (ttl > MAX_CACHE_TTL) ttl = MAX_CACHE_TTL; data->cache_until = round_down_ttl(current_time + ttl, ttl); if (data->data == NULL) { g_free(entry->key); g_free(data); g_free(entry); return -ENOMEM; } /* * We cache the two extra bytes at the start of the message * in a TCP packet. When sending UDP packet, we skip the first * two bytes. This way we do not need to know the format * (UDP/TCP) of the cached message. */ ptr[0] = (data->data_len - 2) / 256; ptr[1] = (data->data_len - 2) - ptr[0] * 256; if (srv->protocol == IPPROTO_UDP) ptr += 2; memcpy(ptr, msg, offset + 12); memcpy(ptr + offset + 12, question, qlen + 1); /* copy also the \0 */ q = (void *) (ptr + offset + 12 + qlen + 1); q->type = htons(type); q->class = htons(class); memcpy(ptr + offset + 12 + qlen + 1 + sizeof(struct domain_question), response, rsplen); if (new_entry == TRUE) { g_hash_table_replace(cache, entry->key, entry); cache_size++; } DBG("cache %d %squestion \"%s\" type %d ttl %d size %zd packet %u " "dns len %u", cache_size, new_entry ? "new " : "old ", question, type, ttl, sizeof(*entry) + sizeof(*data) + data->data_len + qlen, data->data_len, srv->protocol == IPPROTO_TCP ? (unsigned int)(data->data[0] * 256 + data->data[1]) : data->data_len); return 0; } static int ns_resolv(struct server_data *server, struct request_data *req, gpointer request, gpointer name) { GList *list; int sk, err, type = 0; char *dot, *lookup = (char *) name; struct cache_entry *entry; entry = cache_check(request, &type, req->protocol); if (entry != NULL) { int ttl_left = 0; struct cache_data *data; DBG("cache hit %s type %s", lookup, type == 1 ? "A" : "AAAA"); if (type == 1) data = entry->ipv4; else data = entry->ipv6; if (data) { ttl_left = data->valid_until - time(NULL); entry->hits++; } if (data != NULL && req->protocol == IPPROTO_TCP) { send_cached_response(req->client_sk, data->data, data->data_len, NULL, 0, IPPROTO_TCP, req->srcid, data->answers, ttl_left); return 1; } if (data != NULL && req->protocol == IPPROTO_UDP) { int udp_sk = g_io_channel_unix_get_fd( req->ifdata->udp_listener_channel); send_cached_response(udp_sk, data->data, data->data_len, &req->sa, req->sa_len, IPPROTO_UDP, req->srcid, data->answers, ttl_left); return 1; } } sk = g_io_channel_unix_get_fd(server->channel); err = sendto(sk, request, req->request_len, MSG_NOSIGNAL, server->server_addr, server->server_addr_len); if (err < 0) { DBG("Cannot send message to server %s sock %d " "protocol %d (%s/%d)", server->server, sk, server->protocol, strerror(errno), errno); return -EIO; } req->numserv++; /* If we have more than one dot, we don't add domains */ dot = strchr(lookup, '.'); if (dot != NULL && dot != lookup + strlen(lookup) - 1) return 0; if (server->domains != NULL && server->domains->data != NULL) req->append_domain = TRUE; for (list = server->domains; list; list = list->next) { char *domain; unsigned char alt[1024]; struct domain_hdr *hdr = (void *) &alt; int altlen, domlen, offset; domain = list->data; if (domain == NULL) continue; offset = protocol_offset(server->protocol); if (offset < 0) return offset; domlen = strlen(domain) + 1; if (domlen < 5) return -EINVAL; alt[offset] = req->altid & 0xff; alt[offset + 1] = req->altid >> 8; memcpy(alt + offset + 2, request + offset + 2, 10); hdr->qdcount = htons(1); altlen = append_query(alt + offset + 12, sizeof(alt) - 12, name, domain); if (altlen < 0) return -EINVAL; altlen += 12; memcpy(alt + offset + altlen, request + offset + altlen - domlen, req->request_len - altlen - offset + domlen); if (server->protocol == IPPROTO_TCP) { int req_len = req->request_len + domlen - 2; alt[0] = (req_len >> 8) & 0xff; alt[1] = req_len & 0xff; } DBG("req %p dstid 0x%04x altid 0x%04x", req, req->dstid, req->altid); err = send(sk, alt, req->request_len + domlen, MSG_NOSIGNAL); if (err < 0) return -EIO; req->numserv++; } return 0; } static void destroy_request_data(struct request_data *req) { if (req->timeout > 0) g_source_remove(req->timeout); g_free(req->resp); g_free(req->request); g_free(req->name); g_free(req); } static int forward_dns_reply(unsigned char *reply, int reply_len, int protocol, struct server_data *data) { struct domain_hdr *hdr; struct request_data *req; int dns_id, sk, err, offset = protocol_offset(protocol); struct listener_data *ifdata; if (offset < 0) return offset; hdr = (void *)(reply + offset); dns_id = reply[offset] | reply[offset + 1] << 8; DBG("Received %d bytes (id 0x%04x)", reply_len, dns_id); req = find_request(dns_id); if (req == NULL) return -EINVAL; DBG("req %p dstid 0x%04x altid 0x%04x rcode %d", req, req->dstid, req->altid, hdr->rcode); ifdata = req->ifdata; reply[offset] = req->srcid & 0xff; reply[offset + 1] = req->srcid >> 8; req->numresp++; if (hdr->rcode == 0 || req->resp == NULL) { /* * If the domain name was append * remove it before forwarding the reply. */ if (req->append_domain == TRUE) { unsigned int domain_len = 0; unsigned char *ptr; uint8_t host_len; unsigned int header_len; /* * ptr points to the first char of the hostname. * ->hostname.domain.net */ header_len = offset + sizeof(struct domain_hdr); ptr = reply + header_len; host_len = *ptr; if (host_len > 0) domain_len = strnlen((const char *)ptr + 1 + host_len, reply_len - header_len); DBG("host len %d domain len %d", host_len, domain_len); /* * Remove the domain name and replace it by the end * of reply. Check if the domain is really there * before trying to copy the data. The domain_len can * be 0 because if the original query did not contain * a domain name, then we are sending two packets, * first without the domain name and the second packet * with domain name. The append_domain is set to true * even if we sent the first packet without domain * name. In this case we end up in this branch. */ if (domain_len > 0) { /* * Note that we must use memmove() here, * because the memory areas can overlap. */ memmove(ptr + host_len + 1, ptr + host_len + domain_len + 1, reply_len - header_len - domain_len); reply_len = reply_len - domain_len; } } g_free(req->resp); req->resplen = 0; req->resp = g_try_malloc(reply_len); if (req->resp == NULL) return -ENOMEM; memcpy(req->resp, reply, reply_len); req->resplen = reply_len; cache_update(data, reply, reply_len); } if (hdr->rcode > 0 && req->numresp < req->numserv) return -EINVAL; request_list = g_slist_remove(request_list, req); if (protocol == IPPROTO_UDP) { sk = g_io_channel_unix_get_fd(ifdata->udp_listener_channel); err = sendto(sk, req->resp, req->resplen, 0, &req->sa, req->sa_len); } else { sk = req->client_sk; err = send(sk, req->resp, req->resplen, MSG_NOSIGNAL); close(sk); } if (err < 0) DBG("Cannot send msg, sk %d proto %d errno %d/%s", sk, protocol, errno, strerror(errno)); else DBG("proto %d sent %d bytes to %d", protocol, err, sk); destroy_request_data(req); return err; } static void cache_element_destroy(gpointer value) { struct cache_entry *entry = value; if (entry == NULL) return; if (entry->ipv4 != NULL) { g_free(entry->ipv4->data); g_free(entry->ipv4); } if (entry->ipv6 != NULL) { g_free(entry->ipv6->data); g_free(entry->ipv6); } g_free(entry->key); g_free(entry); if (--cache_size < 0) cache_size = 0; } static gboolean try_remove_cache(gpointer user_data) { if (__sync_fetch_and_sub(&cache_refcount, 1) == 1) { DBG("No cache users, removing it."); g_hash_table_destroy(cache); cache = NULL; } return FALSE; } static void server_destroy_socket(struct server_data *data) { DBG("index %d server %s proto %d", data->index, data->server, data->protocol); if (data->watch > 0) { g_source_remove(data->watch); data->watch = 0; } if (data->timeout > 0) { g_source_remove(data->timeout); data->timeout = 0; } if (data->channel != NULL) { g_io_channel_shutdown(data->channel, TRUE, NULL); g_io_channel_unref(data->channel); data->channel = NULL; } g_free(data->incoming_reply); data->incoming_reply = NULL; } static void destroy_server(struct server_data *server) { GList *list; DBG("index %d server %s sock %d", server->index, server->server, server->channel != NULL ? g_io_channel_unix_get_fd(server->channel): -1); server_list = g_slist_remove(server_list, server); server_destroy_socket(server); if (server->protocol == IPPROTO_UDP && server->enabled) DBG("Removing DNS server %s", server->server); g_free(server->server); for (list = server->domains; list; list = list->next) { char *domain = list->data; server->domains = g_list_remove(server->domains, domain); g_free(domain); } g_free(server->server_addr); /* * We do not remove cache right away but delay it few seconds. * The idea is that when IPv6 DNS server is added via RDNSS, it has a * lifetime. When the lifetime expires we decrease the refcount so it * is possible that the cache is then removed. Because a new DNS server * is usually created almost immediately we would then loose the cache * without any good reason. The small delay allows the new RDNSS to * create a new DNS server instance and the refcount does not go to 0. */ g_timeout_add_seconds(3, try_remove_cache, NULL); g_free(server); } static gboolean udp_server_event(GIOChannel *channel, GIOCondition condition, gpointer user_data) { unsigned char buf[4096]; int sk, err, len; struct server_data *data = user_data; if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) { connman_error("Error with UDP server %s", data->server); server_destroy_socket(data); return FALSE; } sk = g_io_channel_unix_get_fd(channel); len = recv(sk, buf, sizeof(buf), 0); if (len < 12) return TRUE; err = forward_dns_reply(buf, len, IPPROTO_UDP, data); if (err < 0) return TRUE; return TRUE; } static gboolean tcp_server_event(GIOChannel *channel, GIOCondition condition, gpointer user_data) { int sk; struct server_data *server = user_data; sk = g_io_channel_unix_get_fd(channel); if (sk == 0) return FALSE; if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) { GSList *list; hangup: DBG("TCP server channel closed, sk %d", sk); /* * Discard any partial response which is buffered; better * to get a proper response from a working server. */ g_free(server->incoming_reply); server->incoming_reply = NULL; for (list = request_list; list; list = list->next) { struct request_data *req = list->data; struct domain_hdr *hdr; if (req->protocol == IPPROTO_UDP) continue; if (req->request == NULL) continue; /* * If we're not waiting for any further response * from another name server, then we send an error * response to the client. */ if (req->numserv && --(req->numserv)) continue; hdr = (void *) (req->request + 2); hdr->id = req->srcid; send_response(req->client_sk, req->request, req->request_len, NULL, 0, IPPROTO_TCP); request_list = g_slist_remove(request_list, req); } destroy_server(server); return FALSE; } if ((condition & G_IO_OUT) && !server->connected) { GSList *list; GList *domains; int no_request_sent = TRUE; struct server_data *udp_server; udp_server = find_server(server->index, server->server, IPPROTO_UDP); if (udp_server != NULL) { for (domains = udp_server->domains; domains; domains = domains->next) { char *dom = domains->data; DBG("Adding domain %s to %s", dom, server->server); server->domains = g_list_append(server->domains, g_strdup(dom)); } } server->connected = TRUE; server_list = g_slist_append(server_list, server); if (server->timeout > 0) { g_source_remove(server->timeout); server->timeout = 0; } for (list = request_list; list; ) { struct request_data *req = list->data; int status; if (req->protocol == IPPROTO_UDP) { list = list->next; continue; } DBG("Sending req %s over TCP", (char *)req->name); status = ns_resolv(server, req, req->request, req->name); if (status > 0) { /* * A cached result was sent, * so the request can be released */ list = list->next; request_list = g_slist_remove(request_list, req); destroy_request_data(req); continue; } if (status < 0) { list = list->next; continue; } no_request_sent = FALSE; if (req->timeout > 0) g_source_remove(req->timeout); req->timeout = g_timeout_add_seconds(30, request_timeout, req); list = list->next; } if (no_request_sent == TRUE) { destroy_server(server); return FALSE; } } else if (condition & G_IO_IN) { struct partial_reply *reply = server->incoming_reply; int bytes_recv; if (!reply) { unsigned char reply_len_buf[2]; uint16_t reply_len; bytes_recv = recv(sk, reply_len_buf, 2, MSG_PEEK); if (!bytes_recv) { goto hangup; } else if (bytes_recv < 0) { if (errno == EAGAIN || errno == EWOULDBLOCK) return TRUE; connman_error("DNS proxy error %s", strerror(errno)); goto hangup; } else if (bytes_recv < 2) return TRUE; reply_len = reply_len_buf[1] | reply_len_buf[0] << 8; reply_len += 2; DBG("TCP reply %d bytes from %d", reply_len, sk); reply = g_try_malloc(sizeof(*reply) + reply_len + 2); if (!reply) return TRUE; reply->len = reply_len; reply->received = 0; server->incoming_reply = reply; } while (reply->received < reply->len) { bytes_recv = recv(sk, reply->buf + reply->received, reply->len - reply->received, 0); if (!bytes_recv) { connman_error("DNS proxy TCP disconnect"); break; } else if (bytes_recv < 0) { if (errno == EAGAIN || errno == EWOULDBLOCK) return TRUE; connman_error("DNS proxy error %s", strerror(errno)); break; } reply->received += bytes_recv; } forward_dns_reply(reply->buf, reply->received, IPPROTO_TCP, server); g_free(reply); server->incoming_reply = NULL; destroy_server(server); return FALSE; } return TRUE; } static gboolean tcp_idle_timeout(gpointer user_data) { struct server_data *server = user_data; DBG(""); if (server == NULL) return FALSE; destroy_server(server); return FALSE; } static int server_create_socket(struct server_data *data) { int sk, err; char *interface; DBG("index %d server %s proto %d", data->index, data->server, data->protocol); sk = socket(data->server_addr->sa_family, data->protocol == IPPROTO_TCP ? SOCK_STREAM : SOCK_DGRAM, data->protocol); if (sk < 0) { err = errno; connman_error("Failed to create server %s socket", data->server); server_destroy_socket(data); return -err; } DBG("sk %d", sk); interface = connman_inet_ifname(data->index); if (interface != NULL) { if (setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE, interface, strlen(interface) + 1) < 0) { err = errno; connman_error("Failed to bind server %s " "to interface %s", data->server, interface); close(sk); server_destroy_socket(data); g_free(interface); return -err; } g_free(interface); } data->channel = g_io_channel_unix_new(sk); if (data->channel == NULL) { connman_error("Failed to create server %s channel", data->server); close(sk); server_destroy_socket(data); return -ENOMEM; } g_io_channel_set_close_on_unref(data->channel, TRUE); if (data->protocol == IPPROTO_TCP) { g_io_channel_set_flags(data->channel, G_IO_FLAG_NONBLOCK, NULL); data->watch = g_io_add_watch(data->channel, G_IO_OUT | G_IO_IN | G_IO_HUP | G_IO_NVAL | G_IO_ERR, tcp_server_event, data); data->timeout = g_timeout_add_seconds(30, tcp_idle_timeout, data); } else data->watch = g_io_add_watch(data->channel, G_IO_IN | G_IO_NVAL | G_IO_ERR | G_IO_HUP, udp_server_event, data); if (connect(sk, data->server_addr, data->server_addr_len) < 0) { err = errno; if ((data->protocol == IPPROTO_TCP && errno != EINPROGRESS) || data->protocol == IPPROTO_UDP) { connman_error("Failed to connect to server %s", data->server); server_destroy_socket(data); return -err; } } if (__sync_fetch_and_add(&cache_refcount, 1) == 0) cache = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, cache_element_destroy); return 0; } static struct server_data *create_server(int index, const char *domain, const char *server, int protocol) { struct server_data *data; struct addrinfo hints, *rp; int ret; DBG("index %d server %s", index, server); data = g_try_new0(struct server_data, 1); if (data == NULL) { connman_error("Failed to allocate server %s data", server); return NULL; } data->index = index; if (domain) data->domains = g_list_append(data->domains, g_strdup(domain)); data->server = g_strdup(server); data->protocol = protocol; memset(&hints, 0, sizeof(hints)); switch (protocol) { case IPPROTO_UDP: hints.ai_socktype = SOCK_DGRAM; break; case IPPROTO_TCP: hints.ai_socktype = SOCK_STREAM; break; default: destroy_server(data); return NULL; } hints.ai_family = AF_UNSPEC; hints.ai_flags = AI_NUMERICSERV | AI_NUMERICHOST; ret = getaddrinfo(data->server, "53", &hints, &rp); if (ret) { connman_error("Failed to parse server %s address: %s\n", data->server, gai_strerror(ret)); destroy_server(data); return NULL; } /* Do not blindly copy this code elsewhere; it doesn't loop over the results using ->ai_next as it should. That's OK in *this* case because it was a numeric lookup; we *know* there's only one. */ data->server_addr_len = rp->ai_addrlen; switch (rp->ai_family) { case AF_INET: data->server_addr = (struct sockaddr *) g_try_new0(struct sockaddr_in, 1); break; case AF_INET6: data->server_addr = (struct sockaddr *) g_try_new0(struct sockaddr_in6, 1); break; default: connman_error("Wrong address family %d", rp->ai_family); break; } if (data->server_addr == NULL) { freeaddrinfo(rp); destroy_server(data); return NULL; } memcpy(data->server_addr, rp->ai_addr, rp->ai_addrlen); freeaddrinfo(rp); if (server_create_socket(data) != 0) { destroy_server(data); return NULL; } if (protocol == IPPROTO_UDP) { /* Enable new servers by default */ data->enabled = TRUE; DBG("Adding DNS server %s", data->server); server_list = g_slist_append(server_list, data); } return data; } static gboolean resolv(struct request_data *req, gpointer request, gpointer name) { GSList *list; for (list = server_list; list; list = list->next) { struct server_data *data = list->data; if (data->protocol == IPPROTO_TCP) { DBG("server %s ignored proto TCP", data->server); continue; } DBG("server %s enabled %d", data->server, data->enabled); if (data->enabled == FALSE) continue; if (data->channel == NULL && data->protocol == IPPROTO_UDP) { if (server_create_socket(data) < 0) { DBG("socket creation failed while resolving"); continue; } } if (ns_resolv(data, req, request, name) > 0) return TRUE; } return FALSE; } static void append_domain(int index, const char *domain) { GSList *list; DBG("index %d domain %s", index, domain); if (domain == NULL) return; for (list = server_list; list; list = list->next) { struct server_data *data = list->data; GList *dom_list; char *dom; gboolean dom_found = FALSE; if (data->index < 0) continue; if (data->index != index) continue; for (dom_list = data->domains; dom_list; dom_list = dom_list->next) { dom = dom_list->data; if (g_str_equal(dom, domain)) { dom_found = TRUE; break; } } if (dom_found == FALSE) { data->domains = g_list_append(data->domains, g_strdup(domain)); } } } int __connman_dnsproxy_append(int index, const char *domain, const char *server) { struct server_data *data; DBG("index %d server %s", index, server); if (server == NULL && domain == NULL) return -EINVAL; if (server == NULL) { append_domain(index, domain); return 0; } if (g_str_equal(server, "127.0.0.1") == TRUE) return -ENODEV; data = find_server(index, server, IPPROTO_UDP); if (data != NULL) { append_domain(index, domain); return 0; } data = create_server(index, domain, server, IPPROTO_UDP); if (data == NULL) return -EIO; return 0; } static void remove_server(int index, const char *domain, const char *server, int protocol) { struct server_data *data; data = find_server(index, server, protocol); if (data == NULL) return; destroy_server(data); } int __connman_dnsproxy_remove(int index, const char *domain, const char *server) { DBG("index %d server %s", index, server); if (server == NULL) return -EINVAL; if (g_str_equal(server, "127.0.0.1") == TRUE) return -ENODEV; remove_server(index, domain, server, IPPROTO_UDP); remove_server(index, domain, server, IPPROTO_TCP); return 0; } void __connman_dnsproxy_flush(void) { GSList *list; list = request_list; while (list) { struct request_data *req = list->data; list = list->next; if (resolv(req, req->request, req->name) == TRUE) { /* * A cached result was sent, * so the request can be released */ request_list = g_slist_remove(request_list, req); destroy_request_data(req); continue; } if (req->timeout > 0) g_source_remove(req->timeout); req->timeout = g_timeout_add_seconds(5, request_timeout, req); } } static void dnsproxy_offline_mode(connman_bool_t enabled) { GSList *list; DBG("enabled %d", enabled); for (list = server_list; list; list = list->next) { struct server_data *data = list->data; if (enabled == FALSE) { DBG("Enabling DNS server %s", data->server); data->enabled = TRUE; cache_invalidate(); cache_refresh(); } else { DBG("Disabling DNS server %s", data->server); data->enabled = FALSE; cache_invalidate(); } } } static void dnsproxy_default_changed(struct connman_service *service) { GSList *list; int index; DBG("service %p", service); /* DNS has changed, invalidate the cache */ cache_invalidate(); if (service == NULL) { /* When no services are active, then disable DNS proxying */ dnsproxy_offline_mode(TRUE); return; } index = __connman_service_get_index(service); if (index < 0) return; for (list = server_list; list; list = list->next) { struct server_data *data = list->data; if (data->index == index) { DBG("Enabling DNS server %s", data->server); data->enabled = TRUE; } else { DBG("Disabling DNS server %s", data->server); data->enabled = FALSE; } } cache_refresh(); } static struct connman_notifier dnsproxy_notifier = { .name = "dnsproxy", .default_changed = dnsproxy_default_changed, .offline_mode = dnsproxy_offline_mode, }; static unsigned char opt_edns0_type[2] = { 0x00, 0x29 }; static int parse_request(unsigned char *buf, int len, char *name, unsigned int size) { struct domain_hdr *hdr = (void *) buf; uint16_t qdcount = ntohs(hdr->qdcount); uint16_t arcount = ntohs(hdr->arcount); unsigned char *ptr; char *last_label = NULL; unsigned int remain, used = 0; if (len < 12) return -EINVAL; DBG("id 0x%04x qr %d opcode %d qdcount %d arcount %d", hdr->id, hdr->qr, hdr->opcode, qdcount, arcount); if (hdr->qr != 0 || qdcount != 1) return -EINVAL; name[0] = '\0'; ptr = buf + sizeof(struct domain_hdr); remain = len - sizeof(struct domain_hdr); while (remain > 0) { uint8_t label_len = *ptr; if (label_len == 0x00) { last_label = (char *) (ptr + 1); break; } if (used + label_len + 1 > size) return -ENOBUFS; strncat(name, (char *) (ptr + 1), label_len); strcat(name, "."); used += label_len + 1; ptr += label_len + 1; remain -= label_len + 1; } if (last_label && arcount && remain >= 9 && last_label[4] == 0 && !memcmp(last_label + 5, opt_edns0_type, 2)) { uint16_t edns0_bufsize; edns0_bufsize = last_label[7] << 8 | last_label[8]; DBG("EDNS0 buffer size %u", edns0_bufsize); /* This is an evil hack until full TCP support has been * implemented. * * Somtimes the EDNS0 request gets send with a too-small * buffer size. Since glibc doesn't seem to crash when it * gets a response biffer then it requested, just bump * the buffer size up to 4KiB. */ if (edns0_bufsize < 0x1000) { last_label[7] = 0x10; last_label[8] = 0x00; } } DBG("query %s", name); return 0; } static gboolean tcp_listener_event(GIOChannel *channel, GIOCondition condition, gpointer user_data) { unsigned char buf[768]; char query[512]; struct request_data *req; int sk, client_sk, len, err; struct sockaddr_in6 client_addr; socklen_t client_addr_len = sizeof(client_addr); GSList *list; struct listener_data *ifdata = user_data; int waiting_for_connect = FALSE, qtype = 0; struct cache_entry *entry; DBG("condition 0x%x", condition); if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) { if (ifdata->tcp_listener_watch > 0) g_source_remove(ifdata->tcp_listener_watch); ifdata->tcp_listener_watch = 0; connman_error("Error with TCP listener channel"); return FALSE; } sk = g_io_channel_unix_get_fd(channel); client_sk = accept(sk, (void *)&client_addr, &client_addr_len); if (client_sk < 0) { connman_error("Accept failure on TCP listener"); ifdata->tcp_listener_watch = 0; return FALSE; } len = recv(client_sk, buf, sizeof(buf), 0); if (len < 2) return TRUE; DBG("Received %d bytes (id 0x%04x) from %d", len, buf[2] | buf[3] << 8, client_sk); err = parse_request(buf + 2, len - 2, query, sizeof(query)); if (err < 0 || (g_slist_length(server_list) == 0)) { send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP); return TRUE; } req = g_try_new0(struct request_data, 1); if (req == NULL) return TRUE; memcpy(&req->sa, &client_addr, client_addr_len); req->sa_len = client_addr_len; req->client_sk = client_sk; req->protocol = IPPROTO_TCP; req->srcid = buf[2] | (buf[3] << 8); req->dstid = get_id(); req->altid = get_id(); req->request_len = len; buf[2] = req->dstid & 0xff; buf[3] = req->dstid >> 8; req->numserv = 0; req->ifdata = (struct listener_data *) ifdata; req->append_domain = FALSE; /* * Check if the answer is found in the cache before * creating sockets to the server. */ entry = cache_check(buf, &qtype, IPPROTO_TCP); if (entry != NULL) { int ttl_left = 0; struct cache_data *data; DBG("cache hit %s type %s", query, qtype == 1 ? "A" : "AAAA"); if (qtype == 1) data = entry->ipv4; else data = entry->ipv6; if (data != NULL) { ttl_left = data->valid_until - time(NULL); entry->hits++; send_cached_response(client_sk, data->data, data->data_len, NULL, 0, IPPROTO_TCP, req->srcid, data->answers, ttl_left); g_free(req); return TRUE; } else DBG("data missing, ignoring cache for this query"); } for (list = server_list; list; list = list->next) { struct server_data *data = list->data; if (data->protocol != IPPROTO_UDP || data->enabled == FALSE) continue; if(create_server(data->index, NULL, data->server, IPPROTO_TCP) == NULL) continue; waiting_for_connect = TRUE; } if (waiting_for_connect == FALSE) { /* No server is waiting for connect */ send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP); g_free(req); return TRUE; } /* * The server is not connected yet. * Copy the relevant buffers. * The request will actually be sent once we're * properly connected over TCP to the nameserver. */ req->request = g_try_malloc0(req->request_len); if (req->request == NULL) { send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP); g_free(req); return TRUE; } memcpy(req->request, buf, req->request_len); req->name = g_try_malloc0(sizeof(query)); if (req->name == NULL) { send_response(client_sk, buf, len, NULL, 0, IPPROTO_TCP); g_free(req->request); g_free(req); return TRUE; } memcpy(req->name, query, sizeof(query)); req->timeout = g_timeout_add_seconds(30, request_timeout, req); request_list = g_slist_append(request_list, req); return TRUE; } static gboolean udp_listener_event(GIOChannel *channel, GIOCondition condition, gpointer user_data) { unsigned char buf[768]; char query[512]; struct request_data *req; struct sockaddr_in6 client_addr; socklen_t client_addr_len = sizeof(client_addr); int sk, err, len; struct listener_data *ifdata = user_data; if (condition & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) { connman_error("Error with UDP listener channel"); ifdata->udp_listener_watch = 0; return FALSE; } sk = g_io_channel_unix_get_fd(channel); memset(&client_addr, 0, client_addr_len); len = recvfrom(sk, buf, sizeof(buf), 0, (void *)&client_addr, &client_addr_len); if (len < 2) return TRUE; DBG("Received %d bytes (id 0x%04x)", len, buf[0] | buf[1] << 8); err = parse_request(buf, len, query, sizeof(query)); if (err < 0 || (g_slist_length(server_list) == 0)) { send_response(sk, buf, len, (void *)&client_addr, client_addr_len, IPPROTO_UDP); return TRUE; } req = g_try_new0(struct request_data, 1); if (req == NULL) return TRUE; memcpy(&req->sa, &client_addr, client_addr_len); req->sa_len = client_addr_len; req->client_sk = 0; req->protocol = IPPROTO_UDP; req->srcid = buf[0] | (buf[1] << 8); req->dstid = get_id(); req->altid = get_id(); req->request_len = len; buf[0] = req->dstid & 0xff; buf[1] = req->dstid >> 8; req->numserv = 0; req->ifdata = (struct listener_data *) ifdata; req->append_domain = FALSE; if (resolv(req, buf, query) == TRUE) { /* a cached result was sent, so the request can be released */ g_free(req); return TRUE; } req->timeout = g_timeout_add_seconds(5, request_timeout, req); request_list = g_slist_append(request_list, req); return TRUE; } static int create_dns_listener(int protocol, struct listener_data *ifdata) { GIOChannel *channel; const char *proto; union { struct sockaddr sa; struct sockaddr_in6 sin6; struct sockaddr_in sin; } s; socklen_t slen; int sk, type, v6only = 0; int family = AF_INET6; char *interface; DBG("index %d", ifdata->index); switch (protocol) { case IPPROTO_UDP: proto = "UDP"; type = SOCK_DGRAM | SOCK_CLOEXEC; break; case IPPROTO_TCP: proto = "TCP"; type = SOCK_STREAM | SOCK_CLOEXEC; break; default: return -EINVAL; } sk = socket(family, type, protocol); if (sk < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) { connman_error("No IPv6 support; DNS proxy listening only on Legacy IP"); family = AF_INET; sk = socket(family, type, protocol); } if (sk < 0) { connman_error("Failed to create %s listener socket", proto); return -EIO; } interface = connman_inet_ifname(ifdata->index); if (interface == NULL || setsockopt(sk, SOL_SOCKET, SO_BINDTODEVICE, interface, strlen(interface) + 1) < 0) { connman_error("Failed to bind %s listener interface", proto); close(sk); g_free(interface); return -EIO; } g_free(interface); /* Ensure it accepts Legacy IP connections too */ if (family == AF_INET6 && setsockopt(sk, SOL_IPV6, IPV6_V6ONLY, &v6only, sizeof(v6only)) < 0) { connman_error("Failed to clear V6ONLY on %s listener socket", proto); close(sk); return -EIO; } if (family == AF_INET) { memset(&s.sin, 0, sizeof(s.sin)); s.sin.sin_family = AF_INET; s.sin.sin_port = htons(53); s.sin.sin_addr.s_addr = htonl(INADDR_ANY); slen = sizeof(s.sin); } else { memset(&s.sin6, 0, sizeof(s.sin6)); s.sin6.sin6_family = AF_INET6; s.sin6.sin6_port = htons(53); s.sin6.sin6_addr = in6addr_any; slen = sizeof(s.sin6); } if (bind(sk, &s.sa, slen) < 0) { connman_error("Failed to bind %s listener socket", proto); close(sk); return -EIO; } if (protocol == IPPROTO_TCP && listen(sk, 10) < 0) { connman_error("Failed to listen on TCP socket"); close(sk); return -EIO; } channel = g_io_channel_unix_new(sk); if (channel == NULL) { connman_error("Failed to create %s listener channel", proto); close(sk); return -EIO; } g_io_channel_set_close_on_unref(channel, TRUE); if (protocol == IPPROTO_TCP) { ifdata->tcp_listener_channel = channel; ifdata->tcp_listener_watch = g_io_add_watch(channel, G_IO_IN, tcp_listener_event, (gpointer) ifdata); } else { ifdata->udp_listener_channel = channel; ifdata->udp_listener_watch = g_io_add_watch(channel, G_IO_IN, udp_listener_event, (gpointer) ifdata); } return 0; } static void destroy_udp_listener(struct listener_data *ifdata) { DBG("index %d", ifdata->index); if (ifdata->udp_listener_watch > 0) g_source_remove(ifdata->udp_listener_watch); g_io_channel_unref(ifdata->udp_listener_channel); } static void destroy_tcp_listener(struct listener_data *ifdata) { DBG("index %d", ifdata->index); if (ifdata->tcp_listener_watch > 0) g_source_remove(ifdata->tcp_listener_watch); g_io_channel_unref(ifdata->tcp_listener_channel); } static int create_listener(struct listener_data *ifdata) { int err, index; err = create_dns_listener(IPPROTO_UDP, ifdata); if (err < 0) return err; err = create_dns_listener(IPPROTO_TCP, ifdata); if (err < 0) { destroy_udp_listener(ifdata); return err; } index = connman_inet_ifindex("lo"); if (ifdata->index == index) __connman_resolvfile_append(index, NULL, "127.0.0.1"); return 0; } static void destroy_listener(struct listener_data *ifdata) { int index; GSList *list; index = connman_inet_ifindex("lo"); if (ifdata->index == index) __connman_resolvfile_remove(index, NULL, "127.0.0.1"); for (list = request_list; list; list = list->next) { struct request_data *req = list->data; DBG("Dropping request (id 0x%04x -> 0x%04x)", req->srcid, req->dstid); destroy_request_data(req); list->data = NULL; } g_slist_free(request_list); request_list = NULL; destroy_tcp_listener(ifdata); destroy_udp_listener(ifdata); } int __connman_dnsproxy_add_listener(int index) { struct listener_data *ifdata; int err; DBG("index %d", index); if (index < 0) return -EINVAL; if (g_hash_table_lookup(listener_table, GINT_TO_POINTER(index)) != NULL) return 0; ifdata = g_try_new0(struct listener_data, 1); if (ifdata == NULL) return -ENOMEM; ifdata->index = index; ifdata->udp_listener_channel = NULL; ifdata->udp_listener_watch = 0; ifdata->tcp_listener_channel = NULL; ifdata->tcp_listener_watch = 0; err = create_listener(ifdata); if (err < 0) { connman_error("Couldn't create listener for index %d err %d", index, err); g_free(ifdata); return err; } g_hash_table_insert(listener_table, GINT_TO_POINTER(ifdata->index), ifdata); return 0; } void __connman_dnsproxy_remove_listener(int index) { struct listener_data *ifdata; DBG("index %d", index); ifdata = g_hash_table_lookup(listener_table, GINT_TO_POINTER(index)); if (ifdata == NULL) return; destroy_listener(ifdata); g_hash_table_remove(listener_table, GINT_TO_POINTER(index)); } static void remove_listener(gpointer key, gpointer value, gpointer user_data) { int index = GPOINTER_TO_INT(key); struct listener_data *ifdata = value; DBG("index %d", index); destroy_listener(ifdata); } int __connman_dnsproxy_init(void) { int err, index; DBG(""); srandom(time(NULL)); listener_table = g_hash_table_new_full(g_direct_hash, g_str_equal, NULL, g_free); index = connman_inet_ifindex("lo"); err = __connman_dnsproxy_add_listener(index); if (err < 0) return err; err = connman_notifier_register(&dnsproxy_notifier); if (err < 0) goto destroy; return 0; destroy: __connman_dnsproxy_remove_listener(index); g_hash_table_destroy(listener_table); return err; } void __connman_dnsproxy_cleanup(void) { DBG(""); connman_notifier_unregister(&dnsproxy_notifier); g_hash_table_foreach(listener_table, remove_listener, NULL); g_hash_table_destroy(listener_table); }