Merge 0cfff2e5da into 287469245c

Don't fail when it wasn't possible to fetch the interface name.

isotpsniffer.c

@@ -59,6 +59,7 @@
 #include <linux/can.h>
 #include <linux/can/isotp.h>
 #include <linux/sockios.h>
+#include <errno.h>
 
 #define NO_CAN_ID 0xFFFFFFFFU
 
@@ -66,6 +67,8 @@
 #define FORMAT_ASCII 2
 #define FORMAT_DEFAULT (FORMAT_ASCII | FORMAT_HEX)
 
+#define PDU_BUF_SIZE 4096
+
 void print_usage(char *prg)
 {
 	fprintf(stderr, "\nUsage: %s [options] <CAN interface>\n", prg);
@@ -79,6 +82,7 @@ void print_usage(char *prg)
 	fprintf(stderr, "         -f <format>  (1 = HEX, 2 = ASCII, 3 = HEX & ASCII - default: %d)\n", FORMAT_DEFAULT);
 	fprintf(stderr, "         -L           (set link layer options for CAN FD)\n");
 	fprintf(stderr, "         -h <len>     (head: print only first <len> bytes)\n");
+	fprintf(stderr, "         -i           (ignore syscall errors to receive malformed PDUs)\n");
 	fprintf(stderr, "\nCAN IDs and addresses are given and expected in hexadecimal values.\n");
 	fprintf(stderr, "\n");
 }
@@ -189,15 +193,16 @@ int main(int argc, char **argv)
 	int head = 0;
 	int timestamp = 0;
 	int format = FORMAT_DEFAULT;
+	int ignore_errors = 0;
 	canid_t src = NO_CAN_ID;
 	canid_t dst = NO_CAN_ID;
 	extern int optind, opterr, optopt;
 	static struct timeval tv, last_tv;
 
-	unsigned char buffer[4096];
+	unsigned char buffer[PDU_BUF_SIZE];
 	int nbytes;
 
-	while ((opt = getopt(argc, argv, "s:d:x:X:h:ct:f:L?")) != -1) {
+	while ((opt = getopt(argc, argv, "s:d:x:X:h:ct:f:L?i")) != -1) {
 		switch (opt) {
 		case 's':
 			src = strtoul(optarg, NULL, 16);
@@ -249,6 +254,10 @@ int main(int argc, char **argv)
 			}
 			break;
 
+		case 'i':
+			ignore_errors = 1;
+			break;
+
 		case '?':
 			print_usage(basename(argv[0]));
 			goto out;
@@ -367,31 +376,37 @@ int main(int argc, char **argv)
 		}
 
 		if (FD_ISSET(s, &rdfs)) {
-			nbytes = read(s, buffer, 4096);
+			nbytes = read(s, buffer, PDU_BUF_SIZE);
 			if (nbytes < 0) {
 				perror("read socket s");
 				r = 1;
+				if(!ignore_errors)
 					goto out;
 			}
-			if (nbytes > 4095) {
+			if (nbytes > (PDU_BUF_SIZE - 1)) {
 				r = 1;
+				fprintf(stderr, "PDU length %d longer than PDU buffer: %s\n", nbytes, strerror(errno));
 				goto out;
 			}
+			if(nbytes > 0)
 				printbuf(buffer, nbytes, color?2:0, timestamp, format,
 					 &tv, &last_tv, dst, s, if_name, head);
 		}
 
 		if (FD_ISSET(t, &rdfs)) {
-			nbytes = read(t, buffer, 4096);
+			nbytes = read(t, buffer, PDU_BUF_SIZE);
 			if (nbytes < 0) {
 				perror("read socket t");
 				r = 1;
+				if(!ignore_errors)
 					goto out;
 			}
-			if (nbytes > 4095) {
+			if (nbytes > (PDU_BUF_SIZE - 1)) {
 				r = 1;
+				fprintf(stderr, "PDU length %d longer than PDU buffer: %s\n", nbytes, strerror(errno));
 				goto out;
 			}
+			if(nbytes > 0)
 				printbuf(buffer, nbytes, color?1:0, timestamp, format,
 					 &tv, &last_tv, src, t, if_name, head);
 		}

slcand.c

@@ -370,8 +370,13 @@ int main(int argc, char *argv[])
 	
 	/* retrieve the name of the created CAN netdevice */
 	if (ioctl(fd, SIOCGIFNAME, ifr.ifr_name) < 0) {
+		if (name) {
 			perror("ioctl SIOCGIFNAME");
 			exit(EXIT_FAILURE);
+		} else {
+			/* Graceful degradation: we only needed the name for display. */
+			snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "<unknown>");
+		}
 	}
 
 	syslogger(LOG_NOTICE, "attached TTY %s to netdevice %s\n", ttypath, ifr.ifr_name);