From 3ecacdf3a6332048def4d1f007b202ab4db628db Mon Sep 17 00:00:00 2001
From: Pedro Alvarez <pedro.alvarez@softwareradiosystems.com>
Date: Tue, 2 Oct 2018 16:29:45 +0100
Subject: [PATCH] Adding selection of local interface at the MBMS-GW.

---
 srsepc/hdr/mbms-gw/mbms-gw.h  | 1 +
 srsepc/mbms.conf.example      | 1 +
 srsepc/src/mbms-gw/main.cc    | 3 +++
 srsepc/src/mbms-gw/mbms-gw.cc | 2 +-
 4 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/srsepc/hdr/mbms-gw/mbms-gw.h b/srsepc/hdr/mbms-gw/mbms-gw.h
index c238c0a18..45046b1d9 100644
--- a/srsepc/hdr/mbms-gw/mbms-gw.h
+++ b/srsepc/hdr/mbms-gw/mbms-gw.h
@@ -51,6 +51,7 @@ typedef struct {
   std::string sgi_mb_if_addr;
   std::string sgi_mb_if_mask;
   std::string m1u_multi_addr;
+  std::string m1u_multi_if;
 } mbms_gw_args_t;
 
 struct pseudo_hdr
diff --git a/srsepc/mbms.conf.example b/srsepc/mbms.conf.example
index d92306328..efe8489d8 100644
--- a/srsepc/mbms.conf.example
+++ b/srsepc/mbms.conf.example
@@ -15,6 +15,7 @@ name = srsmbmsgw01
 sgi_mb_if_addr = 172.16.0.254
 sgi_mb_if_mask = 255.255.255.255
 m1u_multi_addr = 239.255.0.1
+m1u_multi_if   = 127.0.1.200
 
 ####################################################################
 # Log configuration
diff --git a/srsepc/src/mbms-gw/main.cc b/srsepc/src/mbms-gw/main.cc
index f99356071..046b9e27b 100644
--- a/srsepc/src/mbms-gw/main.cc
+++ b/srsepc/src/mbms-gw/main.cc
@@ -85,6 +85,7 @@ parse_args(all_args_t *args, int argc, char* argv[]) {
   string mbms_gw_sgi_mb_if_addr;
   string mbms_gw_sgi_mb_if_mask;
   string mbms_gw_m1u_multi_addr;
+  string mbms_gw_m1u_multi_if;
 
   string log_filename;
 
@@ -103,6 +104,7 @@ parse_args(all_args_t *args, int argc, char* argv[]) {
     ("mbms_gw.sgi_mb_if_addr",      bpo::value<string>(&mbms_gw_sgi_mb_if_addr)->default_value("172.16.1.1"), "SGi-mb TUN interface Address.")
     ("mbms_gw.sgi_mb_if_mask",      bpo::value<string>(&mbms_gw_sgi_mb_if_mask)->default_value("255.255.255.255"), "SGi-mb TUN interface mask.")
     ("mbms_gw.m1u_multi_addr",      bpo::value<string>(&mbms_gw_m1u_multi_addr)->default_value("239.255.0.1"), "M1-u GTPu destination multicast address.")
+    ("mbms_gw.m1u_multi_if",        bpo::value<string>(&mbms_gw_m1u_multi_if)->default_value("127.0.1.200"), "Local interface IP for M1-U multicast packets.")
 
     ("log.all_level",     bpo::value<string>(&args->log_args.all_level)->default_value("info"),   "ALL log level")
     ("log.all_hex_limit", bpo::value<int>(&args->log_args.all_hex_limit)->default_value(32),  "ALL log hex dump limit")
@@ -156,6 +158,7 @@ parse_args(all_args_t *args, int argc, char* argv[]) {
   args->mbms_gw_args.sgi_mb_if_addr = mbms_gw_sgi_mb_if_addr;
   args->mbms_gw_args.sgi_mb_if_mask = mbms_gw_sgi_mb_if_mask;
   args->mbms_gw_args.m1u_multi_addr = mbms_gw_m1u_multi_addr;
+  args->mbms_gw_args.m1u_multi_if   = mbms_gw_m1u_multi_if;
 
   // Apply all_level to any unset layers
   if (vm.count("log.all_level")) {
diff --git a/srsepc/src/mbms-gw/mbms-gw.cc b/srsepc/src/mbms-gw/mbms-gw.cc
index dc8199e27..d8ae96182 100644
--- a/srsepc/src/mbms-gw/mbms-gw.cc
+++ b/srsepc/src/mbms-gw/mbms-gw.cc
@@ -234,7 +234,7 @@ mbms_gw::init_m1_u(mbms_gw_args_t *args)
   /* Set local interface for outbound multicast packets*/
   /* The IP must be associated with a local multicast capable interface */
   struct in_addr local_if;
-  local_if.s_addr = inet_addr("127.0.1.200");
+  local_if.s_addr = inet_addr(args->m1u_multi_if.c_str());
   if(setsockopt(m_m1u, IPPROTO_IP, IP_MULTICAST_IF, (char*)&local_if, sizeof(struct in_addr))<0){
     perror("Error setting multicast interface.\n");
   } else {