X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fmdnsd.git;a=blobdiff_plain;f=dns.c;h=4c3dbf92f6c1e4598d5e07d39ea91b351ad5e190;hp=ebef9ce05a40b01fb66a5500eb73cf942a872ea6;hb=c78cfb1475f755c85949882e0d9d857a800348a1;hpb=4059fe10c18e7ea7309198741f18cf71c6afc911 diff --git a/dns.c b/dns.c index ebef9ce..4c3dbf9 100644 --- a/dns.c +++ b/dns.c @@ -15,6 +15,7 @@ #include #include +#include #include #include #include @@ -39,6 +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* @@ -66,7 +68,7 @@ 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; static struct dns_question q; @@ -76,7 +78,7 @@ dns_send_question(struct interface *iface, const char *question, int type) .iov_len = sizeof(h), }, { - .iov_base = name_buffer, + .iov_base = dns_buffer, }, { .iov_base = &q, @@ -86,19 +88,18 @@ dns_send_question(struct interface *iface, const char *question, int type) int len; h.questions = cpu_to_be16(1); - q.class = 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; - 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); + DBG(1, "Q <- %s %s\n", dns_type_string(type), question); + if (interface_send_packet(iface, NULL, iov, ARRAY_SIZE(iov)) < 0) + perror("failed to send question :"); } @@ -120,7 +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; @@ -129,7 +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); @@ -137,7 +138,7 @@ dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength) } void -dns_send_answer(struct interface *iface, const char *answer) +dns_send_answer(struct interface *iface, struct sockaddr *to, const char *answer) { uint8_t buffer[256]; struct blob_attr *attr; @@ -176,10 +177,39 @@ dns_send_answer(struct interface *iface, const char *answer) DBG(1, "A <- %s %s\n", dns_type_string(be16_to_cpu(a->type)), answer); } - if (interface_send_packet(iface, iov, n_iov) < 0) + if (interface_send_packet(iface, to, iov, n_iov) < 0) fprintf(stderr, "failed to send question\n"); } +void +dns_reply_a(struct interface *iface, struct sockaddr *to, 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, to, mdns_hostname_local); + + freeifaddrs(ifap); +} + static int scan_name(const uint8_t *buffer, int len) { @@ -300,6 +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"); @@ -310,27 +343,49 @@ 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; } static void -parse_question(struct interface *iface, char *name, struct dns_question *q) +parse_question(struct interface *iface, struct sockaddr *from, char *name, struct dns_question *q) { + struct sockaddr *to; char *host; + /* TODO: Multicast if more than one quarter of TTL has passed */ + if ((q->class & CLASS_UNICAST) && iface->multicast) { + iface = iface->peer; + to = from; + } else { + to = NULL; + } + 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)) { + dns_reply_a(iface, to, announce_ttl); + service_reply(iface, to, NULL, announce_ttl); + } break; case TYPE_PTR: - service_announce_services(iface, name); - service_reply(iface, name); + if (!strcmp(name, sdudp)) { + service_announce_services(iface, to, 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, to, dot + 1, announce_ttl); + } break; case TYPE_AAAA: @@ -339,13 +394,13 @@ 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, to, 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; @@ -357,6 +412,10 @@ 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; @@ -373,18 +432,22 @@ dns_handle_packet(struct interface *iface, uint8_t *buffer, int len) } if (!(h->flags & FLAG_RESPONSE)) - parse_question(iface, name, q); + parse_question(iface, s, name, q); } if (!(h->flags & FLAG_RESPONSE)) 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; + }