From e2e82cc464e9f3e913fc342742ea270531f2be36 Mon Sep 17 00:00:00 2001
From: Pedro Alvarez <pedro.alvarez@softwareradiosystems.com>
Date: Fri, 29 Jun 2018 11:27:12 +0100
Subject: [PATCH] Removing broadcats hack. Returning to a simple TUN insterface
 on the MBMS-GW.

---
 srsepc/src/mbms-gw/mbms-gw.cc | 61 +----------------------------------
 1 file changed, 1 insertion(+), 60 deletions(-)

diff --git a/srsepc/src/mbms-gw/mbms-gw.cc b/srsepc/src/mbms-gw/mbms-gw.cc
index a3d18a68d..3031fc1c8 100644
--- a/srsepc/src/mbms-gw/mbms-gw.cc
+++ b/srsepc/src/mbms-gw/mbms-gw.cc
@@ -285,8 +285,6 @@ mbms_gw::handle_sgi_md_pdu(srslte::byte_buffer_t *msg)
 {
   uint8_t version;
   srslte::gtpu_header_t header;
-  in_addr_t baddr = inet_addr("172.16.0.255");
-  in_addr_t saddr = inet_addr("172.16.0.254");
 
   //Setup GTP-U header
   header.flags        = 0x30;
@@ -301,44 +299,14 @@ mbms_gw::handle_sgi_md_pdu(srslte::byte_buffer_t *msg)
     return;
   }
 
-  //IP+UDP Headers
+  //IP Headers
   struct iphdr *iph = (struct iphdr *) msg->msg;
-  struct udphdr *udph = (struct udphdr *) (msg->msg + iph->ihl*4);
   if(iph->version != 4)
   {
     m_mbms_gw_log->warning("IPv6 not supported yet.\n");
     return;
   }
 
-  //Replace Destination IP with broadcast address
-  iph->daddr = baddr;
-
-  //Replace Source IP with address in same subnet
-  iph->saddr = saddr;
-
-  //Replace IP cheksum
-  iph->check = 0;
-  iph->check = in_cksum((uint16_t*)msg->msg,4*(msg->msg[0] & 0x0F));
-
-  //Set Pseudo Header
-  struct pseudo_hdr phdr;
-  phdr.src_addr    = iph->saddr;
-  phdr.dst_addr    = iph->daddr;
-  phdr.protocol    = IPPROTO_UDP;
-  phdr.placeholder = 0;
-  phdr.udp_len     = udph->len;
-
-  //Set Pseudo Datagram
-  udph->check = 0;
-  int psize = sizeof(struct pseudo_hdr) + ntohs(udph->len);
-  uint8_t * pseudo_dgram = (uint8_t*) malloc(psize);
-  memcpy(pseudo_dgram, &phdr,sizeof(struct pseudo_hdr));
-  memcpy(pseudo_dgram+sizeof(pseudo_hdr),udph,ntohs(udph->len));
-
-  //Recompute UDP checksum
-  udph->check = in_cksum((uint16_t*) pseudo_dgram, psize);
-  free(pseudo_dgram);
-
   //Write GTP-U header into packet
   if(!srslte::gtpu_write_header(&header, msg))
   {
@@ -355,31 +323,4 @@ mbms_gw::handle_sgi_md_pdu(srslte::byte_buffer_t *msg)
   }
 }
 
-uint16_t
-mbms_gw::in_cksum(uint16_t *iphdr, int count)
-{
-
-  //RFC 1071
-  uint32_t sum = 0;
-  uint16_t padd = 0;
-  uint16_t result;
-  while(count > 1)
-  {
-    sum+= *iphdr++;
-    count -= 2;
-  }
-  if( count > 0 )
-  {
-    padd = * (uint8_t *) iphdr;
-    sum += padd;
-  }
-  /*Fold 32-bit sum to 16-bit*/
-  //  while(sum>>16)
-  //  sum = (sum & 0xffff) + (sum >> 16);
-  sum = (sum>>16)+(sum & 0xFFFF);
-  sum = sum + (sum >> 16);
-  result = (uint16_t) ~sum;
-  return result;
-}
-
 } //namespace srsepc