X-Git-Url: http://git.openwrt.org/?a=blobdiff_plain;f=dns.c;h=1d3362f8b4953f86d079e8a61edc6390bbf6dda1;hb=cdac0460ba50dc45735f0be2e19a5a8efc3dafe1;hp=1ff5d530f9e4f7d61775ec487b958eb25c57dbcc;hpb=3032203ee12cf5344f89b1ae1ee78229a44f8959;p=project%2Fmdnsd.git

diff --git a/dns.c b/dns.c
index 1ff5d53..1d3362f 100644
--- a/dns.c
+++ b/dns.c
@@ -15,6 +15,7 @@
 #include <sys/stat.h>
 
 #include <fcntl.h>
+#include <ifaddrs.h>
 #include <time.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -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 +68,8 @@ dns_type_string(uint16_t type)
 }
 
 void
-dns_send_question(struct interface *iface, const char *question, int type, int unicast)
+dns_send_question(struct interface *iface, struct sockaddr *to,
+		  const char *question, int type, int multicast)
 {
 	static struct dns_header h;
 	static struct dns_question q;
@@ -76,7 +79,7 @@ dns_send_question(struct interface *iface, const char *question, int type, int u
 			.iov_len = sizeof(h),
 		},
 		{
-			.iov_base = name_buffer,
+			.iov_base = dns_buffer,
 		},
 		{
 			.iov_base = &q,
@@ -86,18 +89,18 @@ dns_send_question(struct interface *iface, const char *question, int type, int u
 	int len;
 
 	h.questions = cpu_to_be16(1);
-	q.class = cpu_to_be16(((unicast) ? (CLASS_UNICAST) : (0))  | 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)
-		perror("failed to send question :");
+	if (interface_send_packet(iface, to, iov, ARRAY_SIZE(iov)) < 0)
+		perror("failed to send question");
 }
 
 
@@ -136,7 +139,7 @@ dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength, int ttl)
 }
 
 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;
@@ -175,8 +178,37 @@ 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)
-		fprintf(stderr, "failed to send question\n");
+	if (interface_send_packet(iface, to, iov, n_iov) < 0)
+		perror("failed to send answer");
+}
+
+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
@@ -190,6 +222,7 @@ scan_name(const uint8_t *buffer, int len)
 		if (IS_COMPRESSED(l))
 			return offset + 2;
 
+		if (l + 1 > len) return -1;
 		len -= l + 1;
 		offset += l + 1;
 		buffer += l + 1;
@@ -205,16 +238,16 @@ static struct dns_header*
 dns_consume_header(uint8_t **data, int *len)
 {
 	struct dns_header *h = (struct dns_header *) *data;
-	uint16_t *swap = (uint16_t *) h;
-	int endianess = 6;
 
 	if (*len < sizeof(struct dns_header))
 		return NULL;
 
-	while (endianess--) {
-		*swap = be16_to_cpu(*swap);
-		swap++;
-	}
+	h->id = be16_to_cpu(h->id);
+	h->flags = be16_to_cpu(h->flags);
+	h->questions = be16_to_cpu(h->questions);
+	h->answers = be16_to_cpu(h->answers);
+	h->authority = be16_to_cpu(h->authority);
+	h->additional = be16_to_cpu(h->additional);
 
 	*len -= sizeof(struct dns_header);
 	*data += sizeof(struct dns_header);
@@ -226,16 +259,12 @@ static struct dns_question*
 dns_consume_question(uint8_t **data, int *len)
 {
 	struct dns_question *q = (struct dns_question *) *data;
-	uint16_t *swap = (uint16_t *) q;
-	int endianess = 2;
 
 	if (*len < sizeof(struct dns_question))
 		return NULL;
 
-	while (endianess--) {
-		*swap = be16_to_cpu(*swap);
-		swap++;
-	}
+	q->type = be16_to_cpu(q->type);
+	q->class = be16_to_cpu(q->class);
 
 	*len -= sizeof(struct dns_question);
 	*data += sizeof(struct dns_question);
@@ -281,14 +310,15 @@ 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)
+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) {
+	if (!name || *rlen < 0) {
 		fprintf(stderr, "dropping: bad question\n");
 		return -1;
 	}
@@ -299,6 +329,9 @@ 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");
@@ -309,30 +342,52 @@ 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, from, 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 = NULL;
 	char *host;
 
-	if ((q->class & CLASS_UNICAST) && iface->multicast)
-		iface = iface->peer;
+	/* 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))
-			service_reply(iface, NULL, announce_ttl);
+		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:
-		service_announce_services(iface, name);
-		service_reply(iface, name, announce_ttl);
+		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:
@@ -340,14 +395,14 @@ parse_question(struct interface *iface, char *name, struct dns_question *q)
 		host = strstr(name, ".local");
 		if (host)
 			*host = '\0';
-		if (!strcmp(mdns_hostname, name))
-			service_reply_a(iface, q->type, announce_ttl);
+		if (!strcmp(umdns_host_label, name))
+			dns_reply_a(iface, to, announce_ttl);
 		break;
 	};
 }
 
 void
-dns_handle_packet(struct interface *iface, uint8_t *buffer, int len, int unicast)
+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;
@@ -359,11 +414,15 @@ dns_handle_packet(struct interface *iface, uint8_t *buffer, int len, int unicast
 		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) {
+		if (!name || rlen < 0) {
 			fprintf(stderr, "dropping: bad name\n");
 			return;
 		}
@@ -375,22 +434,22 @@ dns_handle_packet(struct interface *iface, uint8_t *buffer, int len, int unicast
 		}
 
 		if (!(h->flags & FLAG_RESPONSE))
-			parse_question(iface, name, q);
+			parse_question(iface, from, name, q);
 	}
 
 	if (!(h->flags & FLAG_RESPONSE))
 		return;
 
 	while (h->answers-- > 0)
-		if (parse_answer(iface, buffer, len, &b, &rlen, 1))
+		if (parse_answer(iface, from, buffer, len, &b, &rlen, 1))
 			return;
 
 	while (h->authority-- > 0)
-		if (parse_answer(iface, buffer, len, &b, &rlen, 1))
+		if (parse_answer(iface, from, buffer, len, &b, &rlen, 1))
 			return;
 
 	while (h->additional-- > 0)
-		if (parse_answer(iface, buffer, len, &b, &rlen, 1))
+		if (parse_answer(iface, from, buffer, len, &b, &rlen, 1))
 			return;
 
 }