X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fmdnsd.git;a=blobdiff_plain;f=dns.c;h=495177412fdbd2a38a1043ca2d61c29e4c16b145;hp=5390fe6216097920b9ee08ad59b197950d1dcb8f;hb=2c1fe9afacc9379dcfd0db911fc9ee45adfdc0f4;hpb=4f9d5a0e19d4b480e5b36b5b3b76906f9b35939e diff --git a/dns.c b/dns.c index 5390fe6..4951774 100644 --- a/dns.c +++ b/dns.c @@ -35,8 +35,10 @@ #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]; const char* @@ -65,42 +67,8 @@ dns_type_string(uint16_t type) return "N/A"; } -static int -dns_send_packet(int fd, struct iovec *iov, int iov_len) -{ - static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1]; - 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_control = cmsg_data, - .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)), - }; - struct in_pktinfo *pkti; - struct cmsghdr *cmsg; - - m.msg_iov = iov; - m.msg_iovlen = iov_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; - - a.sin_addr.s_addr = inet_addr(MCAST_ADDR); - - return sendmsg(fd, &m, 0); -} - void -dns_send_question(struct uloop_fd *u, const char *question, int type) +dns_send_question(struct interface *iface, const char *question, int type) { static struct dns_header h = { .questions = cpu_to_be16(1), @@ -131,7 +99,7 @@ dns_send_question(struct uloop_fd *u, const char *question, int type) iov[1].iov_len = len; - if (dns_send_packet(u->fd, iov, ARRAY_SIZE(iov)) < 0) + 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); @@ -169,7 +137,7 @@ dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength) } void -dns_send_answer(struct uloop_fd *u, const char *answer) +dns_send_answer(struct interface *iface, const char *answer) { uint8_t buffer[256]; struct dns_header h = { 0 }; @@ -212,7 +180,7 @@ dns_send_answer(struct uloop_fd *u, const char *answer) DBG(1, "A <- %s %s\n", dns_type_string(dns_reply[i].type), answer); } - if (dns_send_packet(u->fd, iov, (dns_answer_cnt * 3) + 1) < 0) + if (interface_send_packet(iface, iov, (dns_answer_cnt * 3) + 1) < 0) fprintf(stderr, "failed to send question\n"); for (i = 0; i < dns_answer_cnt; i++) { @@ -244,7 +212,7 @@ 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; @@ -265,7 +233,7 @@ 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; @@ -286,7 +254,7 @@ 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; @@ -305,7 +273,7 @@ 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); @@ -323,3 +291,111 @@ dns_consume_name(const 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; + } + + 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); + + return 0; +} + +static void +parse_question(struct interface *iface, char *name, struct dns_question *q) +{ + char *host; + + DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name); + + switch (q->type) { + case TYPE_ANY: + host = service_name("local"); + if (!strcmp(name, host)) + service_reply(iface, NULL); + break; + + case TYPE_PTR: + service_announce_services(iface, name); + service_reply(iface, name); + break; + + case TYPE_AAAA: + case TYPE_A: + host = strstr(name, ".local"); + if (host) + *host = '\0'; + if (!strcmp(hostname, name)) + service_reply_a(iface, q->type); + break; + }; +} + +void +dns_handle_packet(struct interface *iface, 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; + } + + 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) + parse_answer(iface, buffer, len, &b, &rlen, 1); + + while (h->authority-- > 0) + parse_answer(iface, buffer, len, &b, &rlen, 0); + + while (h->additional-- > 0) + parse_answer(iface, buffer, len, &b, &rlen, 1); +}