trafgen: Fix output pcap file name length trimming

Trim output name to IFNAMSIZ only if the output is a networking device,
otherwise the following error occured if output name is greater then
IFNAMSIZ:

  $ trafgen -n 1 '{ udp() }' -o /tmp/xxxxxxxxxxxxxx.pcap
  No networking device or pcap file: /tmp/xxxxxxxxxx
  Failed to open output device

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

trafgen.c

@@ -1084,7 +1084,7 @@ int main(int argc, char **argv)
 			break;
 		case 'd':
 		case 'o':
-			ctx.device = xstrndup(optarg, IFNAMSIZ);
+			ctx.device = xstrdup(optarg);
 			break;
 		case 'H':
 			prio_high = true;

trafgen_dev.c

@@ -174,8 +174,10 @@ struct dev_io *dev_io_open(const char *name, enum dev_io_mode_t mode)
 	struct dev_io *dev = xzmalloc(sizeof(struct dev_io));
 
 	if (strstr(name, ".pcap")) {
+		dev->name = xstrdup(name);
 		dev->ops = &dev_pcap_ops;
 	} else if (device_mtu(name) > 0) {
+		dev->name = xstrndup(name, IFNAMSIZ);
 		dev->ops = &dev_net_ops;
 	} else {
 		fprintf(stderr, "No networking device or pcap file: %s\n", name);
@@ -189,7 +191,6 @@ struct dev_io *dev_io_open(const char *name, enum dev_io_mode_t mode)
 		}
 	}
 
-	dev->name = xstrdup(name);
 	return dev;
 };