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Description: Decrease timeout length during connect().
In cases where a name server is answering with A as well as AAAA records,
but the system to be queried has lost a corresponding address, the TCP
handshake timeout will cause a long delay before allowing the query of
the next address family, or the next address in general.
.
The use of a trivial signal handler for SIGALRM allows the reduction
of this timeout, thus producing better responsiveness for the interactive
user of the Finger service.
Author: Mats Erik Andersson <debian@gisladisker.se>
Forwarded: no
Last-Updated: 2010-03-02
--- a/finger/net.c
+++ b/finger/net.c
@@ -49,14 +49,25 @@
#include <string.h>
#include <unistd.h>
#include <ctype.h>
+#include <signal.h>
#include "finger.h"
+#if ! defined(FINGER_TIMEOUT) || FINGER_TIMEOUT < 1
+# define FINGER_TIMEOUT 5
+#endif
+
+static void trivial_alarm(int sig) {
+ /* Just to trigger EINTR, and to later use it. */
+ return;
+}
+
int netfinger(const char *name) {
register FILE *fp;
register int c, sawret, ateol;
struct addrinfo hints, *result, *resptr;
struct servent *sp;
struct sockaddr_storage sn;
+ struct sigaction sigact, oldsigact;
int s, status;
char *host;
@@ -77,6 +88,10 @@
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
+ sigact.sa_handler = trivial_alarm;
+ sigemptyset(&sigact.sa_mask);
+ sigact.sa_flags = 0;
+
status = getaddrinfo(host, "finger", &hints, &result);
if (status != 0) {
eprintf("finger: unknown host: %s\n", host);
@@ -95,13 +110,21 @@
/* This should probably be removed. */
/* xprintf("[%s]\n", result->ai_canonname); */
+ sigaction(SIGALRM, &sigact, &oldsigact);
+ alarm(FINGER_TIMEOUT);
+
if (connect(s, resptr->ai_addr, resptr->ai_addrlen) < 0) {
+ if ( errno == EINTR )
+ errno = ETIMEDOUT;
close(s);
continue;
}
+ alarm(0);
+ sigaction(SIGALRM, &oldsigact, NULL);
+
/* Connection is now established.
- /* Assemble the gained information. */
+ * Assemble the gained information. */
memcpy(&sn, resptr->ai_addr, resptr->ai_addrlen);
break;
}
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