X-Git-Url: http://git.openwrt.org/?a=blobdiff_plain;f=dns.c;h=dac6f2c167aeb3f6244621ce0c0b6e2db4d018b4;hb=70c66fbbcde868d2fe6034b5f706f1524e4f3d44;hp=fc93f4a4fd88eb686c17cf3e74814972b56f9e3c;hpb=30d33913cb2d8e895ebf1c79595a0ebf901d925b;p=project%2Fmdnsd.git diff --git a/dns.c b/dns.c index fc93f4a..dac6f2c 100644 --- a/dns.c +++ b/dns.c @@ -15,6 +15,7 @@ #include #include +#include #include #include #include @@ -22,7 +23,6 @@ #include #include #include -#include #include #include #include @@ -40,6 +40,7 @@ #include "interface.h" static char name_buffer[MAX_NAME_LEN + 1]; +static char dns_buffer[MAX_NAME_LEN]; static struct blob_buf ans_buf; const char* @@ -67,21 +68,17 @@ dns_type_string(uint16_t type) } void -dns_send_question(struct interface *iface, const char *question, int type) +dns_send_question(struct interface *iface, const char *question, int type, int multicast) { - static struct dns_header h = { - .questions = cpu_to_be16(1), - }; - static struct dns_question q = { - .class = cpu_to_be16(1), - }; + static struct dns_header h; + static struct dns_question q; static struct iovec iov[] = { { .iov_base = &h, .iov_len = sizeof(h), }, { - .iov_base = name_buffer, + .iov_base = dns_buffer, }, { .iov_base = &q, @@ -90,18 +87,19 @@ dns_send_question(struct interface *iface, const char *question, int type) }; int len; - q.type = __cpu_to_be16(type); + h.questions = cpu_to_be16(1); + q.class = cpu_to_be16((multicast ? 0 : CLASS_UNICAST) | 1); + q.type = cpu_to_be16(type); - len = dn_comp(question, (void *) name_buffer, sizeof(name_buffer), NULL, NULL); + len = dn_comp(question, (void *) dns_buffer, sizeof(dns_buffer), NULL, NULL); if (len < 1) return; iov[1].iov_len = len; + DBG(1, "Q <- %s %s\n", dns_type_string(type), question); if (interface_send_packet(iface, iov, ARRAY_SIZE(iov)) < 0) - fprintf(stderr, "failed to send question\n"); - else - DBG(1, "Q <- %s %s\n", dns_type_string(type), question); + perror("failed to send question :"); } @@ -123,7 +121,7 @@ dns_init_answer(void) } void -dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength) +dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength, int ttl) { struct blob_attr *attr; struct dns_answer *a; @@ -132,7 +130,7 @@ dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength) a = blob_data(attr); a->type = cpu_to_be16(type); a->class = cpu_to_be16(1); - a->ttl = cpu_to_be32(announce_ttl); + a->ttl = cpu_to_be32(ttl); a->rdlength = cpu_to_be16(rdlength); memcpy(a + 1, rdata, rdlength); @@ -152,8 +150,8 @@ dns_send_answer(struct interface *iface, const char *answer) if (!dns_answer_cnt) return; - h.answers = __cpu_to_be16(dns_answer_cnt); - h.flags = __cpu_to_be16(0x8400); + h.answers = cpu_to_be16(dns_answer_cnt); + h.flags = cpu_to_be16(0x8400); iov = alloca(sizeof(struct iovec) * ((dns_answer_cnt * 2) + 1)); @@ -183,6 +181,35 @@ dns_send_answer(struct interface *iface, const char *answer) fprintf(stderr, "failed to send question\n"); } +void +dns_reply_a(struct interface *iface, int ttl) +{ + struct ifaddrs *ifap, *ifa; + struct sockaddr_in *sa; + struct sockaddr_in6 *sa6; + + getifaddrs(&ifap); + + dns_init_answer(); + for (ifa = ifap; ifa; ifa = ifa->ifa_next) { + if (strcmp(ifa->ifa_name, iface->name)) + continue; + if (ifa->ifa_addr->sa_family == AF_INET) { + sa = (struct sockaddr_in *) ifa->ifa_addr; + dns_add_answer(TYPE_A, (uint8_t *) &sa->sin_addr, 4, ttl); + } + if (ifa->ifa_addr->sa_family == AF_INET6) { + uint8_t ll_prefix[] = {0xfe, 0x80 }; + sa6 = (struct sockaddr_in6 *) ifa->ifa_addr; + if (!memcmp(&sa6->sin6_addr, &ll_prefix, 2)) + dns_add_answer(TYPE_AAAA, (uint8_t *) &sa6->sin6_addr, 16, ttl); + } + } + dns_send_answer(iface, mdns_hostname_local); + + freeifaddrs(ifap); +} + static int scan_name(const uint8_t *buffer, int len) { @@ -216,7 +243,7 @@ dns_consume_header(uint8_t **data, int *len) return NULL; while (endianess--) { - *swap = __be16_to_cpu(*swap); + *swap = be16_to_cpu(*swap); swap++; } @@ -237,7 +264,7 @@ dns_consume_question(uint8_t **data, int *len) return NULL; while (endianess--) { - *swap = __be16_to_cpu(*swap); + *swap = be16_to_cpu(*swap); swap++; } @@ -255,10 +282,10 @@ dns_consume_answer(uint8_t **data, int *len) if (*len < sizeof(struct dns_answer)) return NULL; - a->type = __be16_to_cpu(a->type); - a->class = __be16_to_cpu(a->class); - a->ttl = __be32_to_cpu(a->ttl); - a->rdlength = __be16_to_cpu(a->rdlength); + a->type = be16_to_cpu(a->type); + a->class = be16_to_cpu(a->class); + a->ttl = be32_to_cpu(a->ttl); + a->rdlength = be16_to_cpu(a->rdlength); *len -= sizeof(struct dns_answer); *data += sizeof(struct dns_answer); @@ -303,6 +330,9 @@ parse_answer(struct interface *iface, uint8_t *buffer, int len, uint8_t **b, int return -1; } + if ((a->class & ~CLASS_FLUSH) != CLASS_IN) + return -1; + rdata = *b; if (a->rdlength > *rlen) { fprintf(stderr, "dropping: bad question\n"); @@ -313,7 +343,7 @@ parse_answer(struct interface *iface, uint8_t *buffer, int len, uint8_t **b, int *b += a->rdlength; if (cache) - cache_answer(iface, buffer, len, name, a, rdata); + cache_answer(iface, buffer, len, name, a, rdata, a->class & CLASS_FLUSH); return 0; } @@ -323,17 +353,33 @@ parse_question(struct interface *iface, char *name, struct dns_question *q) { char *host; + if ((q->class & CLASS_UNICAST) && iface->multicast) + iface = iface->peer; + DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name); switch (q->type) { case TYPE_ANY: - if (!strcmp(name, mdns_hostname_local)) - service_reply(iface, NULL); + if (!strcmp(name, mdns_hostname_local)) { + service_reply(iface, NULL, announce_ttl); + dns_reply_a(iface, announce_ttl); + } break; case TYPE_PTR: - service_announce_services(iface, name); - service_reply(iface, name); + if (!strcmp(name, sdudp)) { + service_announce_services(iface, announce_ttl); + } else { + /* First dot separates instance name from the rest */ + char *dot = strchr(name, '.'); + /* Length of queried instance */ + size_t len = dot ? dot - name : 0; + + /* Make sure it's query for the instance name we use */ + if (len && len == strlen(mdns_hostname) && + !strncmp(name, mdns_hostname, len)) + service_reply(iface, dot + 1, announce_ttl); + } break; case TYPE_AAAA: @@ -342,13 +388,13 @@ parse_question(struct interface *iface, char *name, struct dns_question *q) if (host) *host = '\0'; if (!strcmp(mdns_hostname, name)) - service_reply_a(iface, q->type); + dns_reply_a(iface, announce_ttl); break; }; } void -dns_handle_packet(struct interface *iface, uint8_t *buffer, int len) +dns_handle_packet(struct interface *iface, struct sockaddr *s, uint16_t port, uint8_t *buffer, int len) { struct dns_header *h; uint8_t *b = buffer; @@ -360,6 +406,10 @@ dns_handle_packet(struct interface *iface, uint8_t *buffer, int len) return; } + if (h->questions && !iface->multicast && port != 5353) + /* silently drop unicast questions that dont originate from port 5353 */ + return; + while (h->questions-- > 0) { char *name = dns_consume_name(buffer, len, &b, &rlen); struct dns_question *q; @@ -383,11 +433,15 @@ dns_handle_packet(struct interface *iface, uint8_t *buffer, int len) return; while (h->answers-- > 0) - parse_answer(iface, buffer, len, &b, &rlen, 1); + if (parse_answer(iface, buffer, len, &b, &rlen, 1)) + return; while (h->authority-- > 0) - parse_answer(iface, buffer, len, &b, &rlen, 0); + if (parse_answer(iface, buffer, len, &b, &rlen, 1)) + return; while (h->additional-- > 0) - parse_answer(iface, buffer, len, &b, &rlen, 1); + if (parse_answer(iface, buffer, len, &b, &rlen, 1)) + return; + }