From 0cb90ab61d238148d56c788bbe64fa3120968435 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@osmocom.org>
Date: Wed, 6 Apr 2022 23:14:59 +0200
Subject: [PATCH] add promiscuous mode

---
 tr-bridge.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tr-bridge.c b/tr-bridge.c
index a40bc6a..8f4062f 100644
--- a/tr-bridge.c
+++ b/tr-bridge.c
@@ -73,6 +73,23 @@ static int devname2ifindex(const char *ifname)
 	return ifr.ifr_ifindex;
 }
 
+static int enable_promisc(int sk, int ifindex)
+{
+	struct packet_mreq mreq = {0};
+	int rc;
+
+	mreq.mr_ifindex = ifindex;
+	mreq.mr_type = PACKET_MR_PROMISC;
+
+	rc = setsockopt(sk, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+	if (rc < 0) {
+		fprintf(stderr, "Unable to set promiscuous mode: %s\n", strerror(errno));
+		return rc;
+	}
+
+	return 0;
+}
+
 static int open_packet_socket(int ifindex)
 {
 	struct sockaddr_ll addr;
@@ -101,6 +118,12 @@ static int open_packet_socket(int ifindex)
 		return rc;
 	}
 
+	rc = enable_promisc(fd, ifindex);
+	if (rc < 0) {
+		close(fd);
+		return rc;
+	}
+
 	return fd;
 }