Scan /proc/net/dev on Linux regardless of how we get the interface list.

It's a Linuxism, so it's not necessary on other platforms, and is useful
even if we have getifaddrs().

2 files changed, 170 insertions, 144 deletions

diff --git a/fad-gifc.c b/fad-gifc.c
index 9d96130..d0a2e99 100644
--- a/fad-gifc.c
+++ b/fad-gifc.c
@@ -122,136 +122,6 @@ struct rtentry;		/* declarations in <net/if.h> */
  */
 #define MAX_SA_LEN	255
 
-#ifdef HAVE_PROC_NET_DEV
-/*
- * Get from "/proc/net/dev" all interfaces listed there; if they're
- * already in the list of interfaces we have, that won't add another
- * instance, but if they're not, that'll add them.
- *
- * We don't bother getting any addresses for them; it appears you can't
- * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and,
- * although some other types of addresses can be fetched with SIOCGIFADDR,
- * we don't bother with them for now.
- *
- * We also don't fail if we couldn't open "/proc/net/dev"; we just leave
- * the list of interfaces as is.
- */
-static int
-scan_proc_net_dev(pcap_if_t **devlistp, int fd, char *errbuf)
-{
-	FILE *proc_net_f;
-	char linebuf[512];
-	int linenum;
-	unsigned char *p;
-	char name[512];	/* XXX - pick a size */
-	char *q, *saveq;
-	struct ifreq ifrflags;
-	int ret = 0;
-
-	proc_net_f = fopen("/proc/net/dev", "r");
-	if (proc_net_f == NULL)
-		return (0);
-
-	for (linenum = 1;
-	    fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) {
-		/*
-		 * Skip the first two lines - they're headers.
-		 */
-		if (linenum <= 2)
-			continue;
-
-		p = &linebuf[0];
-
-		/*
-		 * Skip leading white space.
-		 */
-		while (*p != '\0' && isspace(*p))
-			p++;
-		if (*p == '\0' || *p == '\n')
-			continue;	/* blank line */
-
-		/*
-		 * Get the interface name.
-		 */
-		q = &name[0];
-		while (*p != '\0' && !isspace(*p)) {
-			if (*p == ':') {
-				/*
-				 * This could be the separator between a
-				 * name and an alias number, or it could be
-				 * the separator between a name with no
-				 * alias number and the next field.
-				 *
-				 * If there's a colon after digits, it
-				 * separates the name and the alias number,
-				 * otherwise it separates the name and the
-				 * next field.
-				 */
-				saveq = q;
-				while (isdigit(*p))
-					*q++ = *p++;
-				if (*p != ':') {
-					/*
-					 * That was the next field,
-					 * not the alias number.
-					 */
-					q = saveq;
-				}
-				break;
-			} else
-				*q++ = *p++;
-		}
-		*q = '\0';
-
-		/*
-		 * Get the flags for this interface, and skip it if
-		 * it's not up.
-		 */
-		strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
-		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
-			if (errno == ENXIO)
-				continue;
-			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
-			    "SIOCGIFFLAGS: %.*s: %s",
-			    (int)sizeof(ifrflags.ifr_name),
-			    ifrflags.ifr_name,
-			    pcap_strerror(errno));
-			ret = -1;
-			break;
-		}
-		if (!(ifrflags.ifr_flags & IFF_UP))
-			continue;
-
-		/*
-		 * Add an entry for this interface, with no addresses.
-		 */
-		if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL,
-		    errbuf) == -1) {
-			/*
-			 * Failure.
-			 */
-			ret = -1;
-			break;
-		}
-	}
-	if (ret != -1) {
-		/*
-		 * Well, we didn't fail for any other reason; did we
-		 * fail due to an error reading the file?
-		 */
-		if (ferror(proc_net_f)) {
-			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
-			    "Error reading /proc/net/dev: %s",
-			    pcap_strerror(errno));
-			ret = -1;
-		}
-	}
-
-	(void)fclose(proc_net_f);
-	return (ret);
-}
-#endif /* HAVE_PROC_NET_DEV */
-
 /*
  * Get a list of all interfaces that are up and that we can open.
  * Returns -1 on error, 0 otherwise.
@@ -537,20 +407,6 @@ pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
 		}
 	}
 	free(buf);
-
-#ifdef HAVE_PROC_NET_DEV
-	if (ret != -1) {
-		/*
-		 * We haven't had any errors yet; now read "/proc/net/dev",
-		 * and add to the list of interfaces all interfaces listed
-		 * there that we don't already have, because, on Linux,
-		 * SIOCGIFCONF reports only interfaces with IPv4 addresses,
-		 * so you need to read "/proc/net/dev" to get the names of
-		 * the rest of the interfaces.
-		 */
-		ret = scan_proc_net_dev(&devlist, fd, errbuf);
-	}
-#endif
 	(void)close(fd);
 
 	if (ret != -1) {
diff --git a/pcap-linux.c b/pcap-linux.c
index 22339d6..08bd910 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -1774,6 +1774,148 @@ pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
 	return 0;
 }
 
+#ifdef HAVE_PROC_NET_DEV
+/*
+ * Get from "/proc/net/dev" all interfaces listed there; if they're
+ * already in the list of interfaces we have, that won't add another
+ * instance, but if they're not, that'll add them.
+ *
+ * We don't bother getting any addresses for them; it appears you can't
+ * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and,
+ * although some other types of addresses can be fetched with SIOCGIFADDR,
+ * we don't bother with them for now.
+ *
+ * We also don't fail if we couldn't open "/proc/net/dev"; we just leave
+ * the list of interfaces as is.
+ */
+static int
+scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf)
+{
+	FILE *proc_net_f;
+	int fd;
+	char linebuf[512];
+	int linenum;
+	unsigned char *p;
+	char name[512];	/* XXX - pick a size */
+	char *q, *saveq;
+	struct ifreq ifrflags;
+	int ret = 0;
+
+	proc_net_f = fopen("/proc/net/dev", "r");
+	if (proc_net_f == NULL)
+		return (0);
+
+	/*
+	 * Create a socket from which to fetch interface information.
+	 */
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0) {
+		(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
+		    "socket: %s", pcap_strerror(errno));
+		return (-1);
+	}
+
+	for (linenum = 1;
+	    fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) {
+		/*
+		 * Skip the first two lines - they're headers.
+		 */
+		if (linenum <= 2)
+			continue;
+
+		p = &linebuf[0];
+
+		/*
+		 * Skip leading white space.
+		 */
+		while (*p != '\0' && isspace(*p))
+			p++;
+		if (*p == '\0' || *p == '\n')
+			continue;	/* blank line */
+
+		/*
+		 * Get the interface name.
+		 */
+		q = &name[0];
+		while (*p != '\0' && !isspace(*p)) {
+			if (*p == ':') {
+				/*
+				 * This could be the separator between a
+				 * name and an alias number, or it could be
+				 * the separator between a name with no
+				 * alias number and the next field.
+				 *
+				 * If there's a colon after digits, it
+				 * separates the name and the alias number,
+				 * otherwise it separates the name and the
+				 * next field.
+				 */
+				saveq = q;
+				while (isdigit(*p))
+					*q++ = *p++;
+				if (*p != ':') {
+					/*
+					 * That was the next field,
+					 * not the alias number.
+					 */
+					q = saveq;
+				}
+				break;
+			} else
+				*q++ = *p++;
+		}
+		*q = '\0';
+
+		/*
+		 * Get the flags for this interface, and skip it if
+		 * it's not up.
+		 */
+		strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
+		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
+			if (errno == ENXIO)
+				continue;
+			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
+			    "SIOCGIFFLAGS: %.*s: %s",
+			    (int)sizeof(ifrflags.ifr_name),
+			    ifrflags.ifr_name,
+			    pcap_strerror(errno));
+			ret = -1;
+			break;
+		}
+		if (!(ifrflags.ifr_flags & IFF_UP))
+			continue;
+
+		/*
+		 * Add an entry for this interface, with no addresses.
+		 */
+		if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL,
+		    errbuf) == -1) {
+			/*
+			 * Failure.
+			 */
+			ret = -1;
+			break;
+		}
+	}
+	if (ret != -1) {
+		/*
+		 * Well, we didn't fail for any other reason; did we
+		 * fail due to an error reading the file?
+		 */
+		if (ferror(proc_net_f)) {
+			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
+			    "Error reading /proc/net/dev: %s",
+			    pcap_strerror(errno));
+			ret = -1;
+		}
+	}
+
+	(void)close(fd);
+	(void)fclose(proc_net_f);
+	return (ret);
+}
+#endif /* HAVE_PROC_NET_DEV */
+
 /*
  * Description string for the "any" device.
  */
@@ -1782,25 +1924,53 @@ static const char any_descr[] = "Pseudo-device that captures on all interfaces";
 int
 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
 {
+#ifdef HAVE_PROC_NET_DEV
+	/*
+	 * Read "/proc/net/dev", and add to the list of interfaces all
+	 * interfaces listed there that we don't already have, because,
+	 * on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses,
+	 * and even getifaddrs() won't return information about
+	 * interfaces with no addresses, so you need to read "/proc/net/dev"
+	 * to get the names of the rest of the interfaces.
+	 */
+	if (scan_proc_net_dev(alldevsp, errbuf) == -1)
+		return (-1);
+#endif
+
+	/*
+	 * Add the "any" device.
+	 */
 	if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0)
 		return (-1);
 
 #ifdef HAVE_DAG_API
+	/*
+	 * Add DAG devices.
+	 */
 	if (dag_platform_finddevs(alldevsp, errbuf) < 0)
 		return (-1);
 #endif /* HAVE_DAG_API */
 
 #ifdef HAVE_SEPTEL_API
+	/*
+	 * Add Septel devices.
+	 */
 	if (septel_platform_finddevs(alldevsp, errbuf) < 0)
 		return (-1);
 #endif /* HAVE_SEPTEL_API */
 
 #ifdef PCAP_SUPPORT_BT
+	/*
+	 * Add Bluetooth devices.
+	 */
 	if (bt_platform_finddevs(alldevsp, errbuf) < 0)
 		return (-1);
 #endif
 
 #ifdef PCAP_SUPPORT_USB
+	/*
+	 * Add USB devices.
+	 */
 	if (usb_platform_finddevs(alldevsp, errbuf) < 0)
 		return (-1);
 #endif