X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fmdnsd.git;a=blobdiff_plain;f=dns.c;h=aadfdd8f6927806cbdb7108d81c1031559100308;hp=b37f82eb890c682443c14bb7790d1378e93b9300;hb=HEAD;hpb=70ec71015a42e6e4e04b0281b80ec80e5f5f959a diff --git a/dns.c b/dns.c index b37f82e..aadfdd8 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 @@ -35,53 +35,51 @@ #include "announce.h" #include "util.h" #include "dns.h" +#include "cache.h" +#include "service.h" #include "interface.h" -char rdata_buffer[MAX_DATA_LEN + 1]; static char name_buffer[MAX_NAME_LEN + 1]; +static char dns_buffer[MAX_NAME_LEN]; +static struct blob_buf ans_buf; const char* dns_type_string(uint16_t type) { - switch (type) { - case TYPE_A: - return "A"; - - case TYPE_AAAA: - return "AAAA"; - - case TYPE_PTR: - return "PTR"; - - case TYPE_TXT: - return "TXT"; - - case TYPE_SRV: - return "SRV"; + static const struct { + uint16_t type; + char str[5]; + } type_str[] = { + { TYPE_A, "A" }, + { TYPE_AAAA, "AAAA" }, + { TYPE_PTR, "PTR" }, + { TYPE_TXT, "TXT" }, + { TYPE_SRV, "SRV" }, + { TYPE_ANY, "ANY" }, + }; + int i; - case TYPE_ANY: - return "ANY"; + for (i = 0; i < ARRAY_SIZE(type_str); i++) { + if (type == type_str[i].type) + return type_str[i].str; } return "N/A"; } void -dns_send_question(struct interface *iface, const char *question, int type) +dns_send_question(struct interface *iface, struct sockaddr *to, + 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 +88,19 @@ 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; - 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, to, iov, ARRAY_SIZE(iov)) < 0) + perror("failed to send question"); } @@ -113,80 +112,103 @@ struct dns_reply { char *buffer; }; -#define MAX_ANSWER 8 -static struct dns_reply dns_reply[1 + (MAX_ANSWER * 3)]; static int dns_answer_cnt; void dns_init_answer(void) { dns_answer_cnt = 0; + blob_buf_init(&ans_buf, 0); } 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 dns_reply *a = &dns_reply[dns_answer_cnt]; - if (dns_answer_cnt == MAX_ANSWER) - return; - a->rdata = memdup(rdata, rdlength); - a->type = type; - a->rdlength = rdlength; + struct blob_attr *attr; + struct dns_answer *a; + + attr = blob_new(&ans_buf, 0, sizeof(*a) + rdlength); + a = blob_data(attr); + a->type = cpu_to_be16(type); + a->class = cpu_to_be16(1); + a->ttl = cpu_to_be32(ttl); + a->rdlength = cpu_to_be16(rdlength); + memcpy(a + 1, rdata, rdlength); + dns_answer_cnt++; } 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; struct dns_header h = { 0 }; struct iovec *iov; - int len, i; + int answer_len, rem; + int n_iov = 0; 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 * 3) + 1)); - iov[0].iov_base = &h; - iov[0].iov_len = sizeof(struct dns_header); + iov = alloca(sizeof(struct iovec) * ((dns_answer_cnt * 2) + 1)); - for (i = 0; i < dns_answer_cnt; i++) { - struct dns_answer *a = &dns_reply[i].a; - int id = (i * 3) + 1; + iov[n_iov].iov_base = &h; + iov[n_iov].iov_len = sizeof(struct dns_header); + n_iov++; - memset(a, 0, sizeof(*a)); - a->type = __cpu_to_be16(dns_reply[i].type); - a->class = __cpu_to_be16(1); - a->ttl = __cpu_to_be32(announce_ttl); - a->rdlength = __cpu_to_be16(dns_reply[i].rdlength); - - len = dn_comp(answer, buffer, sizeof(buffer), NULL, NULL); - if (len < 1) - return; + answer_len = dn_comp(answer, buffer, sizeof(buffer), NULL, NULL); + if (answer_len < 1) + return; - dns_reply[i].buffer = iov[id].iov_base = memdup(buffer, len); - iov[id].iov_len = len; + blob_for_each_attr(attr, ans_buf.head, rem) { + struct dns_answer *a = blob_data(attr); - iov[id + 1].iov_base = a; - iov[id + 1].iov_len = sizeof(struct dns_answer); + iov[n_iov].iov_base = buffer; + iov[n_iov].iov_len = answer_len; + n_iov++; - iov[id + 2].iov_base = dns_reply[i].rdata; - iov[id + 2].iov_len = dns_reply[i].rdlength; + iov[n_iov].iov_base = blob_data(attr); + iov[n_iov].iov_len = blob_len(attr); + n_iov++; - DBG(1, "A <- %s %s\n", dns_type_string(dns_reply[i].type), answer); + DBG(1, "A <- %s %s\n", dns_type_string(be16_to_cpu(a->type)), answer); } - if (interface_send_packet(iface, iov, (dns_answer_cnt * 3) + 1) < 0) - fprintf(stderr, "failed to send question\n"); + if (interface_send_packet(iface, to, iov, n_iov) < 0) + perror("failed to send answer"); +} - for (i = 0; i < dns_answer_cnt; i++) { - free(dns_reply[i].buffer); - free(dns_reply[i].rdata); +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_answer_cnt = 0; + dns_send_answer(iface, to, mdns_hostname_local); + + freeifaddrs(ifap); } static int @@ -211,7 +233,7 @@ scan_name(const uint8_t *buffer, int len) return offset + 1; } -struct dns_header* +static struct dns_header* dns_consume_header(uint8_t **data, int *len) { struct dns_header *h = (struct dns_header *) *data; @@ -222,7 +244,7 @@ dns_consume_header(uint8_t **data, int *len) return NULL; while (endianess--) { - *swap = __be16_to_cpu(*swap); + *swap = be16_to_cpu(*swap); swap++; } @@ -232,7 +254,7 @@ dns_consume_header(uint8_t **data, int *len) return h; } -struct dns_question* +static struct dns_question* dns_consume_question(uint8_t **data, int *len) { struct dns_question *q = (struct dns_question *) *data; @@ -243,7 +265,7 @@ dns_consume_question(uint8_t **data, int *len) return NULL; while (endianess--) { - *swap = __be16_to_cpu(*swap); + *swap = be16_to_cpu(*swap); swap++; } @@ -253,7 +275,7 @@ dns_consume_question(uint8_t **data, int *len) return q; } -struct dns_answer* +static struct dns_answer* dns_consume_answer(uint8_t **data, int *len) { struct dns_answer *a = (struct dns_answer *) *data; @@ -261,10 +283,10 @@ 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); @@ -272,7 +294,7 @@ dns_consume_answer(uint8_t **data, int *len) return a; } -char* +static char * dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len) { int nlen = scan_name(*data, *len); @@ -290,3 +312,147 @@ dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len) return name_buffer; } + +static int parse_answer(struct interface *iface, struct sockaddr *from, + uint8_t *buffer, int len, uint8_t **b, int *rlen, + int cache) +{ + char *name = dns_consume_name(buffer, len, b, rlen); + struct dns_answer *a; + uint8_t *rdata; + + if (!name) { + fprintf(stderr, "dropping: bad question\n"); + return -1; + } + + a = dns_consume_answer(b, rlen); + if (!a) { + fprintf(stderr, "dropping: bad question\n"); + return -1; + } + + if ((a->class & ~CLASS_FLUSH) != CLASS_IN) + return -1; + + rdata = *b; + if (a->rdlength > *rlen) { + fprintf(stderr, "dropping: bad question\n"); + return -1; + } + + *rlen -= a->rdlength; + *b += a->rdlength; + + if (cache) + cache_answer(iface, from, buffer, len, name, a, rdata, a->class & CLASS_FLUSH); + + return 0; +} + +static void +parse_question(struct interface *iface, struct sockaddr *from, char *name, struct dns_question *q) +{ + struct sockaddr *to = NULL; + char *host; + + /* TODO: Multicast if more than one quarter of TTL has passed */ + if (q->class & CLASS_UNICAST) { + to = from; + if (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)) { + dns_reply_a(iface, to, announce_ttl); + service_reply(iface, to, NULL, NULL, announce_ttl); + } + break; + + case TYPE_PTR: + if (!strcmp(name, C_DNS_SD)) { + dns_reply_a(iface, to, announce_ttl); + service_announce_services(iface, to, announce_ttl); + } else { + if (name[0] == '_') { + service_reply(iface, to, NULL, name, announce_ttl); + } else { + /* First dot separates instance name from the rest */ + char *dot = strchr(name, '.'); + + if (dot) { + *dot = '\0'; + service_reply(iface, to, name, dot + 1, announce_ttl); + *dot = '.'; + } + } + } + break; + + case TYPE_AAAA: + case TYPE_A: + host = strstr(name, ".local"); + if (host) + *host = '\0'; + if (!strcmp(umdns_host_label, name)) + dns_reply_a(iface, to, announce_ttl); + break; + }; +} + +void +dns_handle_packet(struct interface *iface, struct sockaddr *from, uint16_t port, uint8_t *buffer, int len) +{ + struct dns_header *h; + uint8_t *b = buffer; + int rlen = len; + + h = dns_consume_header(&b, &rlen); + if (!h) { + fprintf(stderr, "dropping: bad header\n"); + return; + } + + if (h->questions && !iface->multicast && port != MCAST_PORT) + /* 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; + + if (!name) { + fprintf(stderr, "dropping: bad name\n"); + return; + } + + q = dns_consume_question(&b, &rlen); + if (!q) { + fprintf(stderr, "dropping: bad question\n"); + return; + } + + if (!(h->flags & FLAG_RESPONSE)) + parse_question(iface, from, name, q); + } + + if (!(h->flags & FLAG_RESPONSE)) + return; + + while (h->answers-- > 0) + if (parse_answer(iface, from, buffer, len, &b, &rlen, 1)) + return; + + while (h->authority-- > 0) + if (parse_answer(iface, from, buffer, len, &b, &rlen, 1)) + return; + + while (h->additional-- > 0) + if (parse_answer(iface, from, buffer, len, &b, &rlen, 1)) + return; + +}