From 9004554da35d1e6ab2a2431337dac84d3260f702 Mon Sep 17 00:00:00 2001
From: Joel Cunningham <jcunningham>
Date: Wed, 25 Feb 2015 21:59:21 +0100
Subject: [PATCH] fixed bug #43028 (IP_MULTICAST_TTL affects unicast datagrams)

---
 CHANGELOG              |  4 ++++
 src/api/sockets.c      |  4 ++--
 src/core/udp.c         | 13 ++++++++++++-
 src/include/lwip/udp.h |  6 +++++-
 4 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index c57f4e52..f9d817eb 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -202,6 +202,10 @@ HISTORY
 
   ++ Bugfixes:
 
+  2015-02-25: patch by Joel Cunningham
+  * udp.h/.c, sockets.c: fixed bug #43028 (IP_MULTICAST_TTL affects unicast
+    datagrams)
+
   2015-02-25: patch by Greg Renda
   * ip4_frag.c: fixed bug #38210 (ip reassembly while remove oldest datagram)
 
diff --git a/src/api/sockets.c b/src/api/sockets.c
index dce155e8..a0795b7b 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -1803,7 +1803,7 @@ lwip_getsockopt_impl(int s, int level, int optname, void *optval, socklen_t *opt
       if (NETCONNTYPE_GROUP(netconn_type(sock->conn)) != NETCONN_UDP) {
         return ENOPROTOOPT;
       }
-      *(u8_t*)optval = sock->conn->pcb.ip->ttl;
+      *(u8_t*)optval = sock->conn->pcb.udp->mcast_ttl;
       LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_getsockopt(%d, IPPROTO_IP, IP_MULTICAST_TTL) = %d\n",
                   s, *(int *)optval));
       break;
@@ -2160,7 +2160,7 @@ lwip_setsockopt_impl(int s, int level, int optname, const void *optval, socklen_
 #if LWIP_IGMP
     case IP_MULTICAST_TTL:
       LWIP_SOCKOPT_CHECK_OPTLEN_CONN_PCB_TYPE(sock, optlen, u8_t, NETCONN_UDP);
-      sock->conn->pcb.udp->ttl = (u8_t)(*(u8_t*)optval);
+      sock->conn->pcb.udp->mcast_ttl = (u8_t)(*(u8_t*)optval);
       break;
     case IP_MULTICAST_IF:
       {
diff --git a/src/core/udp.c b/src/core/udp.c
index 155d8b5e..ed9bb28e 100644
--- a/src/core/udp.c
+++ b/src/core/udp.c
@@ -694,6 +694,7 @@ udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *d
   err_t err;
   struct pbuf *q; /* q will be sent down the stack */
   u8_t ip_proto;
+  u8_t ttl;
 
 #if IP_SOF_BROADCAST
   /* broadcast filter? */
@@ -848,11 +849,18 @@ udp_sendto_if_src_chksum(struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *d
     ip_proto = IP_PROTO_UDP;
   }
 
+  /* Determine TTL to use */
+#if LWIP_IGMP
+  ttl = (ip_addr_ismulticast(dst_ip) ? pcb->mcast_ttl : pcb->ttl);
+#else
+  ttl = pcb->ttl;
+#endif
+
   LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04"X16_F"\n", udphdr->chksum));
   LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,0x%02"X16_F",)\n", (u16_t)ip_proto));
   /* output to IP */
   NETIF_SET_HWADDRHINT(netif, &(pcb->addr_hint));
-  err = ipX_output_if_src(PCB_ISIPV6(pcb), q, src_ip, dst_ip, pcb->ttl, pcb->tos, ip_proto, netif);
+  err = ipX_output_if_src(PCB_ISIPV6(pcb), q, src_ip, dst_ip, ttl, pcb->tos, ip_proto, netif);
   NETIF_SET_HWADDRHINT(netif, NULL);
 
   /* TODO: must this be increased even if error occurred? */
@@ -1117,6 +1125,9 @@ udp_new(void)
     /* initialize PCB to all zeroes */
     memset(pcb, 0, sizeof(struct udp_pcb));
     pcb->ttl = UDP_TTL;
+#if LWIP_IGMP
+    pcb->mcast_ttl = UDP_TTL;
+#endif
   }
   return pcb;
 }
diff --git a/src/include/lwip/udp.h b/src/include/lwip/udp.h
index 39c5a6a7..22a6f658 100644
--- a/src/include/lwip/udp.h
+++ b/src/include/lwip/udp.h
@@ -124,6 +124,8 @@ struct udp_pcb {
 #if LWIP_IGMP
   /** outgoing network interface for multicast packets */
   ip_addr_t multicast_ip;
+  /** TTL for outgoing multicast packets */
+  u8_t mcast_ttl;
 #endif /* LWIP_IGMP */
 
 #if LWIP_UDPLITE
@@ -207,8 +209,10 @@ struct udp_pcb * udp_new_ip6(void);
 #endif /* LWIP_IPV6 */
 
 #if LWIP_IGMP
-#define udp_set_multicast_netif_addr(pcb, ip4addr) ((pcb)->multicast_ip = *(ip4addr))
+#define udp_set_multicast_netif_addr(pcb, ip4addr) do { (pcb)->multicast_ip = *(ip4addr); } while(0)
 #define udp_get_multicast_netif_addr(pcb)          (&(pcb)->multicast_ip)
+#define udp_set_multicast_ttl(pcb, mcast_ttl)      do { (pcb)->mcast_ttl = mcast_ttl; } while(0)
+#define udp_get_multicast_ttl(pcb)                 ((pcb)->mcast_ttl)
 #endif /* LWIP_IGMP */
 
 #if UDP_DEBUG