X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fmdnsd.git;a=blobdiff_plain;f=dns.c;h=550befc24c1593ca2f7bcef14fed22456304908f;hp=5595384a544b0f86ba326629defd27a47c2a3b27;hb=9879d5fcafed84a912baa8e2e2d3e73df1a9236d;hpb=2ef1a8ff170ea2c81b3523283dfbc1567297a839 diff --git a/dns.c b/dns.c index 5595384..550befc 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 @@ -35,98 +35,71 @@ #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 uloop_fd *u, char *question, int type) +dns_send_question(struct interface *iface, const char *question, int type, int multicast) { - static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1]; - 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, .iov_len = sizeof(q), } }; - static struct sockaddr_in a = { - .sin_family = AF_INET, - .sin_port = htons(MCAST_PORT), - }; - static struct msghdr m = { - .msg_name = (struct sockaddr *) &a, - .msg_namelen = sizeof(a), - .msg_iov = iov, - .msg_iovlen = ARRAY_SIZE(iov), - .msg_control = cmsg_data, - .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)), - }; - struct in_pktinfo *pkti; - struct cmsghdr *cmsg; int len; - a.sin_addr.s_addr = inet_addr(MCAST_ADDR); - 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; - memset(cmsg_data, 0, sizeof(cmsg_data)); - - cmsg = CMSG_FIRSTHDR(&m); - cmsg->cmsg_len = m.msg_controllen; - cmsg->cmsg_level = IPPROTO_IP; - cmsg->cmsg_type = IP_PKTINFO; - - pkti = (struct in_pktinfo*) CMSG_DATA(cmsg); - pkti->ipi_ifindex = iface_index; - - if (sendmsg(u->fd, &m, 0) < 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, iov, ARRAY_SIZE(iov)) < 0) + perror("failed to send question :"); } @@ -138,98 +111,107 @@ 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, 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 uloop_fd *u, char *answer) +dns_send_answer(struct interface *iface, const char *answer) { uint8_t buffer[256]; + struct blob_attr *attr; struct dns_header h = { 0 }; - struct msghdr m = { 0 }; struct iovec *iov; - struct sockaddr_in in = { 0 }; - int len, i; + int answer_len, rem; + int n_iov = 0; if (!dns_answer_cnt) return; - in.sin_family = AF_INET; - in.sin_addr.s_addr = inet_addr(MCAST_ADDR); - in.sin_port = htons(MCAST_PORT); - - h.answers = __cpu_to_be16(dns_answer_cnt); - h.flags = __cpu_to_be16(0x8400); - - iov = malloc(sizeof(struct iovec) * ((dns_answer_cnt * 3) + 1)); - if (!iov) - return; - - m.msg_name = ∈ - m.msg_namelen = sizeof(struct sockaddr_in); - m.msg_iov = iov; - m.msg_iovlen = (dns_answer_cnt * 3) + 1; + h.answers = cpu_to_be16(dns_answer_cnt); + h.flags = cpu_to_be16(0x8400); - 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 (sendmsg(u->fd, &m, 0) < 0) + if (interface_send_packet(iface, iov, n_iov) < 0) fprintf(stderr, "failed to send question\n"); +} - 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, 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, mdns_hostname_local); + + freeifaddrs(ifap); } static int -scan_name(uint8_t *buffer, int len) +scan_name(const uint8_t *buffer, int len) { int offset = 0; @@ -250,7 +232,7 @@ scan_name(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; @@ -261,7 +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++; } @@ -271,7 +253,7 @@ 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; @@ -282,7 +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++; } @@ -292,7 +274,7 @@ 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; @@ -300,10 +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); @@ -311,8 +293,8 @@ dns_consume_answer(uint8_t **data, int *len) return a; } -char* -dns_consume_name(uint8_t *base, int blen, uint8_t **data, int *len) +static char * +dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len) { int nlen = scan_name(*data, *len); @@ -329,3 +311,129 @@ dns_consume_name(uint8_t *base, int blen, uint8_t **data, int *len) return name_buffer; } + +static int +parse_answer(struct interface *iface, 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, buffer, len, name, a, rdata, a->class & CLASS_FLUSH); + + return 0; +} + +static void +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, announce_ttl); + dns_reply_a(iface, announce_ttl); + } + break; + + case TYPE_PTR: + if (!strcmp(name, sdudp)) + service_announce_services(iface, 0, announce_ttl); + else if (!strcmp(name, sdtcp)) + service_announce_services(iface, 1, announce_ttl); + service_reply(iface, name, announce_ttl); + break; + + case TYPE_AAAA: + case TYPE_A: + host = strstr(name, ".local"); + if (host) + *host = '\0'; + if (!strcmp(mdns_hostname, name)) + dns_reply_a(iface, announce_ttl); + break; + }; +} + +void +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; + int rlen = len; + + h = dns_consume_header(&b, &rlen); + if (!h) { + fprintf(stderr, "dropping: bad header\n"); + 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; + + 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, name, q); + } + + if (!(h->flags & FLAG_RESPONSE)) + return; + + while (h->answers-- > 0) + if (parse_answer(iface, buffer, len, &b, &rlen, 1)) + return; + + while (h->authority-- > 0) + if (parse_answer(iface, buffer, len, &b, &rlen, 1)) + return; + + while (h->additional-- > 0) + if (parse_answer(iface, buffer, len, &b, &rlen, 1)) + return; + +}