Blame SOURCES/arpwatch-2.1a15-lookupiselect.patch

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diff -up ./arpwatch.c.iselect ./arpwatch.c
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--- ./arpwatch.c.iselect	2012-10-15 16:01:24.701335291 +0200
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+++ ./arpwatch.c	2012-10-15 16:07:18.626322639 +0200
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@@ -162,50 +162,52 @@ void dropprivileges(const char* user)
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 }
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 char *
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-get_first_dev(pcap_t **pd, int *linktype, char *errbuf)
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+try_dev(char *interface, pcap_t **pd, int *linktype, char *errbuf)
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 {
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-	static char interface[IF_NAMESIZE + 1];
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 	register int snaplen, timeout;
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-	pcap_if_t *alldevs;
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-	pcap_if_t *dev;
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-	char *ret = NULL;
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 	snaplen = max(sizeof(struct ether_header),
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 				  sizeof(struct fddi_header)) + sizeof(struct ether_arp);
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 	timeout = 1000;
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-	if (pcap_findalldevs(&alldevs, errbuf) == -1) {
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-		(void)fprintf(stderr, "%s: lookup_device: %s\n",
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-					  prog, errbuf);
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-		exit(1);
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+	*pd = pcap_open_live(interface, snaplen, 1, timeout, errbuf);
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+	if (NULL == pd) {
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+		syslog(LOG_ERR, "pcap open %s: %s", interface,  errbuf);
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+		return NULL;
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 	}
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+	*linktype = pcap_datalink(*pd);
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+	/* Must be ethernet or fddi */
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+	if (*linktype != DLT_EN10MB && *linktype != DLT_FDDI) {
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+		syslog(LOG_ERR, "(%s) Link layer type %d not ethernet or fddi",
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+			   interface, *linktype);
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+		pcap_close(*pd);
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+		return NULL;
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+	}
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+	return interface;
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+}
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-	for (dev = alldevs; dev; dev = dev->next) {
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-		strncpy(interface, dev->name, strlen(dev->name)+1);
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-
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-		*pd = pcap_open_live(interface, snaplen, 1, timeout, errbuf);
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-		if (*pd == NULL) {
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-			syslog(LOG_ERR, "pcap open %s: %s, trying next...", interface, errbuf);
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-			continue;
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-			/* exit(1); */
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-		}
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+char *
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+iterate_dev(char *arginterface, pcap_t **pd, int *linktype, char *errbuf)
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+{
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+	static char interface[IF_NAMESIZE + 1];
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+	pcap_if_t *alldevs;
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+	pcap_if_t *dev;
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-		*linktype = pcap_datalink(*pd);
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-		/* Must be ethernet or fddi */
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-		if (*linktype != DLT_EN10MB && *linktype != DLT_FDDI) {
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-			syslog(LOG_ERR, "(%s) Link layer type %d not ethernet or fddi, trying next...",
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-				   interface, *linktype);
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-			pcap_close(*pd);
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+	if (NULL != arginterface) {
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+		return try_dev(arginterface, pd, linktype, errbuf);
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+	} else {
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+		if (pcap_findalldevs(&alldevs, errbuf) == -1) {
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+			(void)fprintf(stderr, "%s: lookup_device: %s\n",
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+						  prog, errbuf);
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+			exit(1);
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 		}
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-		else {
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-			/* First match, use it */
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-			ret = interface;
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-			break;
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+		for (dev = alldevs; dev && (arginterface == NULL); dev = dev->next) {
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+			strncpy(interface, dev->name, strlen(dev->name)+1);
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+			arginterface = try_dev(interface, pd, linktype, errbuf);
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 		}
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-
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+		pcap_freealldevs(alldevs);
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+		return arginterface;
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 	}
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-	pcap_freealldevs(alldevs);
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-	return (ret);
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 }
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 int
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@@ -315,8 +317,8 @@ main(int argc, char **argv)
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 	} else {
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 		/* Determine interface if not specified */
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-		if (interface == NULL &&
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-			(interface = get_first_dev(&pd, &linktype, errbuf)) == NULL) {
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+		interface = iterate_dev(interface, &pd, &linktype, errbuf);
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+		if (interface == NULL) {
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 			(void)fprintf(stderr, "%s: lookup_device: no suitable interface found\n",
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 						  prog);
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 			exit(1);