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Fix the handling of the "any" device, including making it reject

attempts to open it in monitor mode.
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yuguy committed Nov 19, 2008
1 parent edbdc85 commit 8fa17a5a554aaeb85d3ec4118b45a31f1efd6808
Showing with 42 additions and 26 deletions.
  1. +42 −26 pcap-linux.c
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@@ -34,7 +34,7 @@
#ifndef lint
static const char rcsid[] _U_ =
- "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.158 2008-10-28 00:50:20 guy Exp $ (LBL)";
+ "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.159 2008-11-19 08:20:39 guy Exp $ (LBL)";
#endif
/*
@@ -297,6 +297,12 @@ pcap_create(const char *device, char *ebuf)
{
pcap_t *handle;
+ /*
+ * A null device name is equivalent to the "any" device.
+ */
+ if (device == NULL)
+ device = "any";
+
#ifdef HAVE_DAG_API
if (strstr(device, "dag")) {
return dag_create(device, ebuf);
@@ -338,10 +344,9 @@ pcap_can_set_rfmon_linux(pcap_t *p)
struct iwreq ireq;
#endif
- if (p->opt.source == NULL) {
+ if (strcmp(p->opt.source, "any") == 0) {
/*
- * This is equivalent to the "any" device, and we don't
- * support monitor mode on it.
+ * Monitor mode makes no sense on the "any" device.
*/
return 0;
}
@@ -518,23 +523,21 @@ pcap_activate_linux(pcap_t *handle)
handle->stats_op = pcap_stats_linux;
/*
- * NULL and "any" are special devices which give us the hint to
- * monitor all devices.
+ * The "any" device is a special device which causes us not
+ * to bind to a particular device and thus to look at all
+ * devices.
*/
- if (!device || strcmp(device, "any") == 0) {
- device = NULL;
- handle->md.device = strdup("any");
+ if (strcmp(device, "any") == 0) {
if (handle->opt.promisc) {
handle->opt.promisc = 0;
/* Just a warning. */
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Promiscuous mode not supported on the \"any\" device");
status = PCAP_WARNING_PROMISC_NOTSUP;
}
+ }
- } else
- handle->md.device = strdup(device);
-
+ handle->md.device = strdup(device);
if (handle->md.device == NULL) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s",
pcap_strerror(errno) );
@@ -1657,19 +1660,21 @@ static int
activate_new(pcap_t *handle)
{
#ifdef HAVE_PF_PACKET_SOCKETS
+ const char *device = handle->opt.source;
+ int is_any_device = (strcmp(device, "any") == 0);
int sock_fd = -1, arptype, val;
int err = 0;
struct packet_mreq mr;
- const char* device = handle->opt.source;
/*
- * Open a socket with protocol family packet. If a device is
- * given we try to open it in raw mode otherwise we use
- * the cooked interface.
+ * Open a socket with protocol family packet. If the
+ * "any" device was specified, we open a SOCK_DGRAM
+ * socket for the cooked interface, otherwise we first
+ * try a SOCK_RAW socket for the raw interface.
*/
- sock_fd = device ?
- socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
- : socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
+ sock_fd = is_any_device ?
+ socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) :
+ socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (sock_fd == -1) {
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
@@ -1704,7 +1709,7 @@ activate_new(pcap_t *handle)
* to cooked mode if we have an unknown interface type
* or a type we know doesn't work well in raw mode.
*/
- if (device) {
+ if (!is_any_device) {
/* Assume for now we don't need cooked mode. */
handle->md.cooked = 0;
@@ -1819,15 +1824,23 @@ activate_new(pcap_t *handle)
}
} else {
/*
- * This is cooked mode.
+ * The "any" device.
+ */
+ if (handle->opt.rfmon) {
+ /*
+ * It doesn't support monitor mode.
+ */
+ return PCAP_ERROR_RFMON_NOTSUP;
+ }
+
+ /*
+ * It uses cooked mode.
*/
handle->md.cooked = 1;
handle->linktype = DLT_LINUX_SLL;
/*
* We're not bound to a device.
- * XXX - true? Or true only if we're using
- * the "any" device?
* For now, we're using this as an indication
* that we can't transmit; stop doing that only
* if we figure out how to transmit in cooked
@@ -1852,10 +1865,13 @@ activate_new(pcap_t *handle)
/*
* Hmm, how can we set promiscuous mode on all interfaces?
- * I am not sure if that is possible at all.
+ * I am not sure if that is possible at all. For now, we
+ * silently ignore attempts to turn promiscuous mode on
+ * for the "any" device (so you don't have to explicitly
+ * disable it in programs such as tcpdump).
*/
- if (device && handle->opt.promisc) {
+ if (!is_any_device && handle->opt.promisc) {
memset(&mr, 0, sizeof(mr));
mr.mr_ifindex = handle->md.ifindex;
mr.mr_type = PACKET_MR_PROMISC;
@@ -3118,7 +3134,7 @@ activate_old(pcap_t *handle)
/* Bind to the given device */
- if (!device) {
+ if (strcmp(device, "any") == 0) {
strncpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
PCAP_ERRBUF_SIZE);
return PCAP_ERROR;

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