87 lines
3.2 KiB
Diff
87 lines
3.2 KiB
Diff
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diff --git a/protocol/discovery/mdns.c b/protocol/discovery/mdns.c
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index 92e153a..75ef0ea 100644
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--- a/protocol/discovery/mdns.c
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+++ b/protocol/discovery/mdns.c
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@@ -436,7 +436,7 @@ static int mdns_read_single_response(int udp_socket, char *recvbuffer, int recvb
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FD_SET(udp_socket, &master);
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maxfd = udp_socket;
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tmo.tv_sec = 0;
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- tmo.tv_usec = 300000;
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+ tmo.tv_usec = 10000;
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readfd = master;
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ret = select(maxfd + 1, &readfd, NULL, NULL, &tmo);
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@@ -549,6 +549,34 @@ static void mdns_rr_cleanup(DNS_RECORD *rr)
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}
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}
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+static DNS_RECORD* send_and_receive(struct mdns_socket *mdns_sock,
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+ const char *name,
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+ int query_type, int read_mode)
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+{
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+ /* wait up to ~1s */
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+ const useconds_t DELTA_T = 251000;
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+ const int RETRIES = 8;
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+ int retry = RETRIES;
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+ DNS_RECORD *rr_list;
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+
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+ while (retry) {
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+ if (mdns_send_query(mdns_sock, name, query_type) == MDNS_STATUS_OK) {
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+ rr_list = mdns_read_responses(mdns_sock->socket, read_mode, name);
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+ if (rr_list != NULL) {
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+ DBG("send_and_receive: got response after %d retries\n",
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+ RETRIES - retry);
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+ return rr_list;
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+ }
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+ }
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+ /* MDNS servers delay responses. If the server just responded
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+ * to some query (maybe an earlier one we sent), we may need to wait. */
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+ --retry;
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+ usleep(DELTA_T);
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+ }
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+ BUG("send_and_receive: no response after %d retries\n", RETRIES);
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+ return NULL;
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+}
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+
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int mdns_probe_nw_scanners(char* uris_buf, int buf_size, int *count)
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{
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int n = 0, bytes_read = 0;
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@@ -562,11 +590,7 @@ int mdns_probe_nw_scanners(char* uris_buf, int buf_size, int *count)
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if (mdns_open_socket(&mdns_sock) != MDNS_STATUS_OK)
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goto bugout;
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- /* Send dns query */
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- mdns_send_query(&mdns_sock, scanner_name, QTYPE_PTR);
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-
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- /* Read Responses */
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- rr_list = mdns_read_responses(mdns_sock.socket, MODE_READ_ALL, scanner_name);
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+ rr_list = send_and_receive(&mdns_sock, scanner_name, QTYPE_PTR, MODE_READ_ALL);
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/* Update URIs buffer */
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bytes_read = mdns_update_uris(rr_list, uris_buf, buf_size, count);
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@@ -598,10 +622,8 @@ int mdns_lookup(char* hostname, unsigned char* ip)
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/* Send dns query */
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sprintf(fqdn, "%s.local", hostname);
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- mdns_send_query(&mdns_sock, fqdn, QTYPE_A);
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- /* Read Responses */
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- rr_list = mdns_read_responses(mdns_sock.socket, MODE_READ_SINGLE, fqdn);
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+ rr_list = send_and_receive(&mdns_sock, fqdn, QTYPE_A, MODE_READ_SINGLE);
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/* Update IP Address buffer */
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if(rr_list)
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diff --git a/protocol/discovery/mdns.h b/protocol/discovery/mdns.h
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index 34066fb..56d8847 100644
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--- a/protocol/discovery/mdns.h
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+++ b/protocol/discovery/mdns.h
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@@ -102,5 +102,8 @@ static int mdns_parse_respponse(unsigned char *Response, DNS_RECORD *rr);
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static void mdns_rr_cleanup(DNS_RECORD *rr);
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static DNS_RECORD *mdns_read_responses(int udp_socket, int mode, const char *question);
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static unsigned char* mdns_readMDL(unsigned char *p, unsigned char *normalized_mdl, int len);
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+static DNS_RECORD* send_and_receive(struct mdns_socket *mdns_sock, const char *name,
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+ int query_type, int read_mode);
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+static int get_ipv4_address(const char *iface, struct in_addr *addr);
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#endif // _DISCOVERY_MDNS_H
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