@@ -1,5 +1,6 @@
#include <sys/types.h>
#include <sys/socket.h>
+#include <netinet/in.h>
#include <unistd.h>
#include "socket.h"
#include "alloc.h"
@@ -98,29 +99,46 @@ static int thisudp(struct dns_transmit *d)
{
const char *ip;
- socketfree(d);
+ /* open a new socket if there isn't already one */
+ if (! d->s1) {
+ /* choose a random port number for this socket */
+ d->query[2] = dns_random(256);
+ d->query[3] = dns_random(256);
+
+ d->s1 = 1 + socket_udp();
+
+ if (! d->s1) {
+ dns_transmit_free(d);
+ return -1;
+ }
+
+ if (randombind(d) == -1) {
+ dns_transmit_free(d);
+ return -1;
+ }
+ }
while (d->udploop < 4) {
for (;d->curserver < 16;++d->curserver) {
ip = d->servers + 4 * d->curserver;
if (byte_diff(ip,4,"\0\0\0\0")) {
- d->query[2] = dns_random(256);
- d->query[3] = dns_random(256);
-
- d->s1 = 1 + socket_udp();
- if (!d->s1) { dns_transmit_free(d); return -1; }
- if (randombind(d) == -1) { dns_transmit_free(d); return -1; }
-
- if (socket_connect4(d->s1 - 1,ip,53) == 0)
- if (send(d->s1 - 1,d->query + 2,d->querylen - 2,0) == d->querylen - 2) {
- struct taia now;
- taia_now(&now);
- taia_uint(&d->deadline,timeouts[d->udploop]);
- taia_add(&d->deadline,&d->deadline,&now);
- d->tcpstate = 0;
- return 0;
- }
-
+ struct sockaddr_in sa;
+
+ /* set the destination address */
+ byte_zero(&sa, sizeof sa);
+ sa.sin_family = AF_INET;
+ uint16_pack_big((char *) &sa.sin_port, 53);
+ byte_copy((char *) &sa.sin_addr, 4, ip);
+
+ if (sendto(d->s1 - 1,d->query + 2,d->querylen - 2,0, (struct sockaddr *) &sa, sizeof sa) == d->querylen - 2) {
+ struct taia now;
+ taia_now(&now);
+ taia_uint(&d->deadline,timeouts[d->udploop]);
+ taia_add(&d->deadline,&d->deadline,&now);
+ d->tcpstate = 0;
+ return 0;
+ }
+
socketfree(d);
}
}
dns_transmit.c
debbbf2f6e481e1ffb12cf819bf8bb0b6d2f52e1
Nick Andrew
nick@nick-andrew.net
http://github.com/nickandrew/djbdns/commit/4c155b646086305964868ba2e4e9aaec8be79fcb
4c155b646086305964868ba2e4e9aaec8be79fcb
2009-06-13T19:35:44-07:00
2009-06-12T18:24:14-07:00
Reuse the socket when resending the same query
Previously, dnscache would create a new socket for each UDP request sent
to a name server. If one query required several requests to different
servers because, say, the server responses timed out, dnscache would
close and reopen the socket each time.
Now, each time a request is resent to a different nameserver, reuse
the socket. Don't bind the socket to a destination, and use sendto()
instead of send(). Process the first response received. The socket is
subsequently closed, so any later responses will be ignored.
In a high latency situation (e.g. 5 second RTT on responses) this
results in a considerable improvement in speed and reliability. A
query for 'A www.telstra.net' took 310 sec in unpatched dnscache
and 16 sec after this change was applied.
Signed-off-by: Nick Andrew <nick@nick-andrew.net>
2feeec8456d4cb8a255e9b0dab8d36e5ded5f314
Nick Andrew
nick@nick-andrew.net