fix off by one in record find code
[project/mdnsd.git] / dns.c
diff --git a/dns.c b/dns.c
index 75e739d..ebef9ce 100644 (file)
--- a/dns.c
+++ b/dns.c
@@ -22,7 +22,6 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
-#include <asm/byteorder.h>
 #include <arpa/nameser.h>
 #include <resolv.h>
 #include <stdlib.h>
 #include "announce.h"
 #include "util.h"
 #include "dns.h"
+#include "cache.h"
+#include "service.h"
+#include "interface.h"
 
-char *rdata_buffer;
-static char *name_buffer;
+static char name_buffer[MAX_NAME_LEN + 1];
+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)
 {
-       static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
-       static unsigned char buffer[MAX_NAME_LEN];
-       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 = buffer,
+                       .iov_base = name_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(1);
+       q.type = cpu_to_be16(type);
 
-       len = dn_comp(question, buffer, MAX_NAME_LEN, NULL, NULL);
+       len = dn_comp(question, (void *) name_buffer, sizeof(name_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)
+       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);
@@ -139,98 +110,78 @@ 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)
 {
-       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(announce_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;
+       h.answers = cpu_to_be16(dns_answer_cnt);
+       h.flags = cpu_to_be16(0x8400);
 
-       m.msg_name = &in;
-       m.msg_namelen = sizeof(struct sockaddr_in);
-       m.msg_iov = iov;
-       m.msg_iovlen = (dns_answer_cnt * 3) + 1;
+       iov = alloca(sizeof(struct iovec) * ((dns_answer_cnt * 2) + 1));
 
-       iov[0].iov_base = &h;
-       iov[0].iov_len = sizeof(struct dns_header);
+       iov[n_iov].iov_base = &h;
+       iov[n_iov].iov_len = sizeof(struct dns_header);
+       n_iov++;
 
-       for (i = 0; i < dns_answer_cnt; i++) {
-               struct dns_answer *a = &dns_reply[i].a;
-               int id = (i * 3) + 1;
-
-               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);
-       }
-       dns_answer_cnt = 0;
 }
 
 static int
-scan_name(uint8_t *buffer, int len)
+scan_name(const uint8_t *buffer, int len)
 {
        int offset = 0;
 
@@ -251,7 +202,7 @@ 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;
@@ -262,7 +213,7 @@ dns_consume_header(uint8_t **data, int *len)
                return NULL;
 
        while (endianess--) {
-               *swap = __be16_to_cpu(*swap);
+               *swap = be16_to_cpu(*swap);
                swap++;
        }
 
@@ -272,7 +223,7 @@ 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;
@@ -283,7 +234,7 @@ dns_consume_question(uint8_t **data, int *len)
                return NULL;
 
        while (endianess--) {
-               *swap = __be16_to_cpu(*swap);
+               *swap = be16_to_cpu(*swap);
                swap++;
        }
 
@@ -293,7 +244,7 @@ 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;
@@ -301,10 +252,10 @@ 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);
@@ -312,8 +263,8 @@ 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);
 
@@ -331,24 +282,109 @@ dns_consume_name(uint8_t *base, int blen, uint8_t **data, int *len)
        return name_buffer;
 }
 
-int
-dns_init(void)
+static int
+parse_answer(struct interface *iface, uint8_t *buffer, int len, uint8_t **b, int *rlen, int cache)
 {
-       name_buffer = malloc(MAX_NAME_LEN + 1);
-       rdata_buffer = malloc(MAX_DATA_LEN + 1);
+       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;
+       }
 
-       if (!name_buffer || !rdata_buffer)
+       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;
 
-       memset(name_buffer, 0, MAX_NAME_LEN + 1);
-       memset(rdata_buffer, 0, MAX_NAME_LEN + 1);
+       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:
+               if (!strcmp(name, mdns_hostname_local))
+                       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(mdns_hostname, name))
+                       service_reply_a(iface, q->type);
+               break;
+       };
+}
+
 void
-dns_cleanup(void)
+dns_handle_packet(struct interface *iface, uint8_t *buffer, int len)
 {
-       free(name_buffer);
-       free(rdata_buffer);
+       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);
 }