ongrep

commit d0c17df8f9a7f017023aef80702ac41e33ade245
parent ebb4be69e99ab8f89058405c70ec6a4089f03674
Author: Stephen Gregoratto <dev@sgregoratto.me>
Date:   Wed, 24 Jun 2020 20:59:19 +1000

Properly check pcap return vals, drop pcap_lookupdev

Rewrite setup_pcap_source to use pcap_findalldevs instead of the
deprecated pcap_lookupdev. Changed the function to return -1 on err.
Also went and properly check error return values.

Diffstat:
M
ngrep.c
 | 
41
++++++++++++++++++++++++++++-------------

1 file changed, 28 insertions(+), 13 deletions(-)
diff --git a/ngrep.c b/ngrep.c
@@ -273,7 +273,7 @@ main(int argc, char **argv)
 		match_data = argv[optind++];
 
 	/* Setup PCAP input */
-	if (setup_pcap_source())
+	if (setup_pcap_source() == -1)
 		clean_exit(-1);
 
 	/*
@@ -314,12 +314,12 @@ main(int argc, char **argv)
 
 	/* Misc */
 	if (dump_file) {
-		pd_dump = pcap_dump_open(pd, dump_file);
-		if (!pd_dump) {
+		if ((pd_dump = pcap_dump_open(pd, dump_file)) == NULL) {
 			warnx("pcap_dump_open: %s", pcap_geterr(pd));
 			clean_exit(-2);
-		} else
+		} else {
 			printf("output: %s\n", dump_file);
+		}
 	}
 	update_windowsize(0);
 
@@ -335,26 +335,38 @@ int
 setup_pcap_source(void)
 {
 	if (read_file) {
-		if (!(pd = pcap_open_offline(read_file, pc_err))) {
+		if ((pd = pcap_open_offline(read_file, pc_err)) == NULL) {
 			warnx("pcap_open_offline: %s", pc_err);
-			return 1;
+			return -1;
 		}
 		live_read = 0;
 		printf("input: %s\n", read_file);
 	} else {
 		char *dev;
+		pcap_if_t *devs = NULL;
 
 		if (usedev != NULL) {
 			dev = usedev;
-		} else if ((dev = pcap_lookupdev(pc_err)) == NULL) {
-			warnx("pcap_lookupdev: %s", pc_err);
-			return 1;
+		} else {
+			if (pcap_findalldevs(&devs, pc_err) == PCAP_ERROR) {
+				warnx("pcap_findalldevs: %s", pc_err);
+				return -1;
+			}
+			if (devs == NULL) {
+				warnx("pcap_findalldevs: no devices found");
+				return -1;
+			}
+
+			dev = devs->name;
 		}
-		if ((pd = pcap_open_live(dev, snaplen, promisc, to, pc_err)) == NULL) {
+
+		pd = pcap_open_live(dev, snaplen, promisc, to, pc_err);
+		if (pd == NULL) {
 			warnx("pcap_open_live: %s", pc_err);
-			return 1;
+			return -1;
 		}
-		if (pcap_lookupnet(dev, &net.s_addr, &mask.s_addr, pc_err) == -1) {
+		if (pcap_lookupnet(dev, &net.s_addr, &mask.s_addr, pc_err) ==
+		    PCAP_ERROR) {
 			warnx("pcap_lookupnet: %s", pc_err);
 			memset(&net, 0, sizeof(net));
 			memset(&mask, 0, sizeof(mask));
@@ -366,6 +378,8 @@ setup_pcap_source(void)
 				       inet_ntoa(net), inet_ntoa(mask));
 			printf("\n");
 		}
+
+		pcap_freealldevs(devs);
 	}
 
 	switch (pcap_datalink(pd)) {
@@ -403,8 +417,9 @@ setup_pcap_source(void)
 	default:
 		warnx("fatal: unsupported interface type %u",
 		      pcap_datalink(pd));
-		return 1;
+		return -1;
 	}
+
 	return 0;
 }