#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*
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";
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;
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;
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;
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);
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:
+ 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_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);
+}