From: Florian Forster <octo@collectd.org>
Date: Wed, 24 Apr 2013 19:55:06 +0000 (+0200)
Subject: dns plugin: Resume after receiving a PCAP_ERROR from pcap_loop().
X-Git-Tag: collectd-5.3.1~4^2~9
X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=b8f9530ad6ba3a55f129d259c705d9b5d4d3f4e5;p=collectd.git

dns plugin: Resume after receiving a PCAP_ERROR from pcap_loop().

If an interface goes down while capturing, libpcap returns PCAP_ERROR.
Handle this case gracefully.

Github: #308
---

diff --git a/src/dns.c b/src/dns.c
index fe3b672a..aea41c43 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -208,7 +208,7 @@ static void dns_child_callback (const rfc1035_header_t *dns)
 	pthread_mutex_unlock (&opcode_mutex);
 }
 
-static void *dns_child_loop (__attribute__((unused)) void *dummy)
+static int dns_run_pcap_loop (void)
 {
 	pcap_t *pcap_obj;
 	char    pcap_error[PCAP_ERRBUF_SIZE];
@@ -236,19 +236,24 @@ static void *dns_child_loop (__attribute__((unused)) void *dummy)
 				"failed: %s",
 				(pcap_device != NULL) ? pcap_device : "any",
 				pcap_error);
-		return (NULL);
+		return (PCAP_ERROR);
 	}
 
 	memset (&fp, 0, sizeof (fp));
-	if (pcap_compile (pcap_obj, &fp, "udp port 53", 1, 0) < 0)
+	status = pcap_compile (pcap_obj, &fp, "udp port 53", 1, 0);
+	if (status < 0)
 	{
-		ERROR ("dns plugin: pcap_compile failed");
-		return (NULL);
+		ERROR ("dns plugin: pcap_compile failed: %s",
+				pcap_statustostr (status));
+		return (status);
 	}
-	if (pcap_setfilter (pcap_obj, &fp) < 0)
+
+	status = pcap_setfilter (pcap_obj, &fp);
+	if (status < 0)
 	{
-		ERROR ("dns plugin: pcap_setfilter failed");
-		return (NULL);
+		ERROR ("dns plugin: pcap_setfilter failed: %s",
+				pcap_statustostr (status));
+		return (status);
 	}
 
 	DEBUG ("dns plugin: PCAP object created.");
@@ -259,19 +264,30 @@ static void *dns_child_loop (__attribute__((unused)) void *dummy)
 	status = pcap_loop (pcap_obj,
 			-1 /* loop forever */,
 			handle_pcap /* callback */,
-			NULL /* Whatever this means.. */);
-	if (status < 0)
-		ERROR ("dns plugin: Listener thread is exiting "
-				"abnormally: %s", pcap_geterr (pcap_obj));
-
-	DEBUG ("dns plugin: Child is exiting.");
+			NULL /* user data */);
+	INFO ("dns plugin: pcap_loop exited with status %i.", status);
+	/* We need to handle "PCAP_ERROR" specially because libpcap currently
+	 * doesn't return PCAP_ERROR_IFACE_NOT_UP for compatibility reasons. */
+	if (status == PCAP_ERROR)
+		status = PCAP_ERROR_IFACE_NOT_UP;
 
 	pcap_close (pcap_obj);
-	listen_thread_init = 0;
-	pthread_exit (NULL);
+	return (status);
+} /* int dns_run_pcap_loop */
+
+static void *dns_child_loop (__attribute__((unused)) void *dummy) /* {{{ */
+{
+	int status = PCAP_ERROR_IFACE_NOT_UP;
+
+	while (status == PCAP_ERROR_IFACE_NOT_UP)
+		status = dns_run_pcap_loop ();
+	if (status != PCAP_ERROR_BREAK)
+		ERROR ("dns plugin: PCAP returned error %s.",
+				pcap_statustostr (status));
 
+	listen_thread_init = 0;
 	return (NULL);
-} /* static void dns_child_loop (void) */
+} /* }}} void *dns_child_loop */
 
 static int dns_init (void)
 {