Attachment 599990 Details for Bug 842660 – [Patch] find suitable default interface

[patch] [Patch] find suitable default interface

arpwatch-2.1a15-devlookup.patch (text/plain), 3.25 KB, created by Jan Synacek on 2012-07-24 11:52:10 UTC

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Creator: Jan Synacek

Created: 2012-07-24 11:52:10 UTC

Size: 3.25 KB

patch

obsolete

>--- arpwatch-2.1a15-dist/arpwatch.c	2012-07-23 09:55:35.832458313 +0200
>+++ arpwatch-2.1a15-new/arpwatch.c	2012-07-24 11:36:59.013953071 +0200
>@@ -161,15 +161,63 @@ void dropprivileges(const char* user)
> 	syslog(LOG_DEBUG, "Running as uid=%d gid=%d", getuid(), getgid());
> }
> 
>+char *
>+get_first_dev(pcap_t **pd, int *linktype, char *errbuf)
>+{
>+	static char interface[IF_NAMESIZE + 1];
>+	register int snaplen, timeout;
>+	pcap_if_t *alldevs;
>+	pcap_if_t *dev;
>+	char *ret = NULL;
>+
>+	snaplen = max(sizeof(struct ether_header),
>+				  sizeof(struct fddi_header)) + sizeof(struct ether_arp);
>+	timeout = 1000;
>+
>+	if (pcap_findalldevs(&alldevs, errbuf) == -1) {
>+		(void)fprintf(stderr, "%s: lookup_device: %s\n",
>+					  prog, errbuf);
>+		exit(1);
>+	}
>+
>+	for (dev = alldevs; dev; dev = dev->next) {
>+		strncpy(interface, dev->name, strlen(dev->name)+1);
>+
>+		*pd = pcap_open_live(interface, snaplen, 1, timeout, errbuf);
>+		if (*pd == NULL) {
>+			syslog(LOG_ERR, "pcap open %s: %s, trying next...", interface, errbuf);
>+			continue;
>+			/* exit(1); */
>+		}
>+
>+		*linktype = pcap_datalink(*pd);
>+		/* Must be ethernet or fddi */
>+		if (*linktype != DLT_EN10MB && *linktype != DLT_FDDI) {
>+			syslog(LOG_ERR, "(%s) Link layer type %d not ethernet or fddi, trying next...",
>+				   interface, *linktype);
>+			pcap_close(*pd);
>+		}
>+		else {
>+			/* First match, use it */
>+			ret = interface;
>+			break;
>+		}
>+
>+	}
>+	pcap_freealldevs(alldevs);
>+	return (ret);
>+}
>+
> int
> main(int argc, char **argv)
> {
> 	register char *cp;
>-	register int op, pid, snaplen, timeout, linktype, status;
>+	register int op, pid, status;
>+	int linktype;
> #ifdef TIOCNOTTY
> 	register int fd;
> #endif
>-	register pcap_t *pd;
>+	pcap_t *pd;
> 	register char *interface, *rfilename;
> 	struct bpf_program code;
> 	char errbuf[PCAP_ERRBUF_SIZE];
>@@ -189,6 +237,7 @@ main(int argc, char **argv)
> 
> 	opterr = 0;
> 	interface = NULL;
>+	linktype = -1;
> 	rfilename = NULL;
> 	pd = NULL;
> 	while ((op = getopt(argc, argv, "df:i:n:Nr:u:e:s:")) != EOF)
>@@ -264,11 +313,12 @@ main(int argc, char **argv)
> 		net = 0;
> 		netmask = 0;
> 	} else {
>+
> 		/* Determine interface if not specified */
> 		if (interface == NULL &&
>-		    (interface = pcap_lookupdev(errbuf)) == NULL) {
>-			(void)fprintf(stderr, "%s: lookup_device: %s\n",
>-			    prog, errbuf);
>+			(interface = get_first_dev(&pd, &linktype, errbuf)) == NULL) {
>+			(void)fprintf(stderr, "%s: lookup_device: no suitable interface found\n",
>+						  prog);
> 			exit(1);
> 		}
> 
>@@ -317,10 +367,6 @@ main(int argc, char **argv)
> 		}
> 		swapped = pcap_is_swapped(pd);
> 	} else {
>-		snaplen = max(sizeof(struct ether_header),
>-		    sizeof(struct fddi_header)) + sizeof(struct ether_arp);
>-		timeout = 1000;
>-		pd = pcap_open_live(interface, snaplen, 1, timeout, errbuf);
> 		if (pd == NULL) {
> 			syslog(LOG_ERR, "pcap open %s: %s", interface, errbuf);
> 			exit(1);
>@@ -340,14 +386,6 @@ main(int argc, char **argv)
> 		dropprivileges( serveruser );
> 	}
> 
>-	/* Must be ethernet or fddi */
>-	linktype = pcap_datalink(pd);
>-	if (linktype != DLT_EN10MB && linktype != DLT_FDDI) {
>-		syslog(LOG_ERR, "Link layer type %d not ethernet or fddi",
>-		    linktype);
>-		exit(1);
>-	}
>-
> 	/* Compile and install filter */
> 	if (pcap_compile(pd, &code, "arp or rarp", 1, netmask) < 0) {
> 		syslog(LOG_ERR, "pcap_compile: %s", pcap_geterr(pd));

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Attachments on bug 842660: 599990