From: guy <guy>
Date: Wed, 9 Apr 2003 07:19:49 +0000 (+0000)
Subject: Don't turn allmulti mode on if "promisc" isn't set; that causes problems
X-Git-Tag: libpcap-0.8-bp~55
X-Git-Url: https://git.tcpdump.org/libpcap/commitdiff_plain/b3833482d01c9415a718842805b0f1f4fab28801

Don't turn allmulti mode on if "promisc" isn't set; that causes problems
with some interfaces (see bug 599857 in the SourceForge list of libpcap
bugs), and, even if it doesn't cause problems, it's different from
what's done on other platforms.
---

diff --git a/pcap-linux.c b/pcap-linux.c
index deb9ae65..895363c9 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -26,7 +26,7 @@
  */
 #ifndef lint
 static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.88 2003-01-23 07:24:52 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.89 2003-04-09 07:19:49 guy Exp $ (LBL)";
 #endif
 
 /*
@@ -1271,18 +1271,29 @@ live_open_new(pcap_t *handle, const char *device, int promisc,
 			device_id = -1;
 		}
 
-		/* Select promiscuous mode on/off */
+		/*
+		 * Select promiscuous mode on if "promisc" is set.
+		 *
+		 * Do not turn allmulti mode on if we don't select
+		 * promiscuous mode - on some devices (e.g., Orinoco
+		 * wireless interfaces), allmulti mode isn't supported
+		 * and the driver implements it by turning promiscuous
+		 * mode on, and that screws up the operation of the
+		 * card as a normal networking interface, and on no
+		 * other platform I know of does starting a non-
+		 * promiscuous capture affect which multicast packets
+		 * are received by the interface.
+		 */
 
 		/*
 		 * Hmm, how can we set promiscuous mode on all interfaces?
 		 * I am not sure if that is possible at all.
 		 */
 
-		if (device) {
+		if (device && promisc) {
 			memset(&mr, 0, sizeof(mr));
 			mr.mr_ifindex = device_id;
-			mr.mr_type    = promisc ?
-				PACKET_MR_PROMISC : PACKET_MR_ALLMULTI;
+			mr.mr_type    = PACKET_MR_PROMISC;
 			if (setsockopt(sock_fd, SOL_PACKET,
 				PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
 			{