Revert my revision 3777b91f70ab86e67c1e039d08fb6d87e06f20d6, which

removed the select() code in child DNS processes.  Stu pointed out
that this code is what allowed our child DNS processes to hang
around for 40 seconds waiting for additional requests, then die a
natural death.

But that wasn't happening even WITH the select code because the parent
was killing the DNS children when it was done with them.  So I
made another change to set the resolver to NULL so that it isn't
killed by purple_dnsquery_destroy().

I'm assuming that we still want our DNS lookup children to hang around
for a little while after they're done.  I reduced the timeout from 40
seconds to 20 seconds.

An arguably better way to do this is to go back to having the child
block on read() instead of calling select(), then have the parent
set a timer that kills the child after a certain about of time.  But
I don't see an advantage to doing it either way, and this is simpler.

1 files changed, 17 insertions, 0 deletions

diff --git a/libpurple/dnsquery.c b/libpurple/dnsquery.c
index 8b51692d57..0a9d5955b0 100644
--- a/libpurple/dnsquery.c
+++ b/libpurple/dnsquery.c
@@ -108,6 +108,13 @@ purple_dnsquery_resolved(PurpleDnsQueryData *query_data, GSList *hosts)
 		}
 	}
 
+	/*
+	 * Set the resolver to NULL so that it doesn't get killed so that
+	 * it sits around waiting for additional DNS requests for a few
+	 * seconds longer.
+	 */
+	query_data->resolver = NULL;
+
 	purple_dnsquery_destroy(query_data);
 }
 
@@ -209,6 +216,16 @@ purple_dnsquery_resolver_run(int child_out, int child_in, gboolean show_debug)
 	 * the result back to our parent, when finished.
 	 */
 	while (1) {
+		fd_set fds;
+		struct timeval tv = { .tv_sec = 20, .tv_usec = 0 };
+		FD_ZERO(&fds);
+		FD_SET(child_in, &fds);
+		rc = select(child_in + 1, &fds, NULL, NULL, &tv);
+		if (!rc) {
+			if (show_debug)
+				printf("dns[%d]: nobody needs me... =(\n", getpid());
+			break;
+		}
 		rc = read(child_in, &dns_params, sizeof(dns_params_t));
 		if (rc < 0) {
 			fprintf(stderr, "dns[%d]: Error: Could not read dns_params: "