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authorGuy Harris <guy@alum.mit.edu>2010-01-10 10:56:25 -0800
committerGuy Harris <guy@alum.mit.edu>2010-01-10 10:56:25 -0800
commit81a96c3226964543ab7a0cb27948793e7882a6f7 (patch)
tree7d24d39348cac08425e529868aa37b217a347582 /pcap-linux.c
parent2fd233b16d6fd907d707877c9c18f7e6bd0edfaf (diff)
Scan /sys/class/net if we have it.
It's a bit easier to scan than /proc/net/dev, as it's a directory.
Diffstat (limited to 'pcap-linux.c')
-rw-r--r--pcap-linux.c152
1 files changed, 144 insertions, 8 deletions
diff --git a/pcap-linux.c b/pcap-linux.c
index b502821..4e1a22e 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -136,6 +136,7 @@ static const char rcsid[] _U_ =
#include <linux/if_ether.h>
#include <net/if_arp.h>
#include <poll.h>
+#include <dirent.h>
/*
* Got Wireless Extensions?
@@ -1776,7 +1777,7 @@ pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
}
/*
- * Get from "/proc/net/dev" all interfaces listed there; if they're
+ * Get from "/sys/class/net" 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.
*
@@ -1785,8 +1786,133 @@ pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
* 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.
+ * We also don't fail if we couldn't open "/sys/class/net"; we just leave
+ * the list of interfaces as is, and return 0, so that we can try
+ * scanning /proc/net/dev.
+ */
+static int
+scan_sys_class_net(pcap_if_t **devlistp, char *errbuf)
+{
+ DIR *sys_class_net_d;
+ int fd;
+ struct dirent *ent;
+ char linebuf[512];
+ int linenum;
+ char *p;
+ char name[512]; /* XXX - pick a size */
+ char *q, *saveq;
+ struct ifreq ifrflags;
+ int ret = 1;
+
+ sys_class_net_d = opendir("/sys/class/net");
+ if (sys_class_net_d == NULL && errno == ENOENT)
+ 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 (;;) {
+ errno = 0;
+ ent = readdir(sys_class_net_d);
+ if (ent == NULL) {
+ /*
+ * Error or EOF; if errno != 0, it's an error.
+ */
+ break;
+ }
+
+ /*
+ * Get the interface name.
+ */
+ q = &ent->d_name[0];
+ while (*p != '\0' && isascii(*p) && !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 (isascii(*p) && 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 (errno != 0) {
+ /*
+ * Error reading the directory.
+ */
+ (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
+ "Error reading /sys/class/net: %s",
+ pcap_strerror(errno));
+ ret = -1;
+ }
+
+ (void)close(fd);
+ (void)closedir(sys_class_net_d);
+ return (ret);
+}
+
+/*
+ * 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.
+ *
+ * See comments from scan_sys_class_net().
*/
static int
scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf)
@@ -1802,7 +1928,7 @@ scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf)
int ret = 0;
proc_net_f = fopen("/proc/net/dev", "r");
- if (proc_net_f == NULL)
+ if (proc_net_f == NULL && errno == ENOENT)
return (0);
/*
@@ -1923,16 +2049,26 @@ static const char any_descr[] = "Pseudo-device that captures on all interfaces";
int
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
{
+ int ret;
+
/*
- * Read "/proc/net/dev", and add to the list of interfaces all
+ * Read "/sys/class/net", 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"
+ * interfaces with no addresses, so you need to read "/sys/class/net"
* to get the names of the rest of the interfaces.
*/
- if (scan_proc_net_dev(alldevsp, errbuf) == -1)
- return (-1);
+ ret = scan_sys_class_net(alldevsp, errbuf);
+ if (ret == -1)
+ return (-1); /* failed */
+ if (ret == 0) {
+ /*
+ * No /sys/class/net; try reading /proc/net/dev instead.
+ */
+ if (scan_proc_net_dev(alldevsp, errbuf) == -1)
+ return (-1);
+ }
/*
* Add the "any" device.