allow multicast socket options IP_MULTICAST_TTL, IP_MULTICAST_IF and IP_MULTICAST_LOOP to be used without IGMP

src/include/lwip/ip4.h

@@ -128,9 +128,9 @@ err_t ip4_output_if_opt_src(struct pbuf *p, const ip4_addr_t *src, const ip4_add
        u16_t optlen);
 #endif /* IP_OPTIONS_SEND */
 
-#if LWIP_IGMP
+#if LWIP_MULTICAST_TX_OPTIONS
 void  ip4_set_default_multicast_netif(struct netif* default_multicast_netif);
-#endif /* LWIP_IGMP */
+#endif /* LWIP_MULTICAST_TX_OPTIONS */
 
 #define ip4_netif_get_local_ip(netif) (((netif) != NULL) ? &((netif)->ip_addr) : NULL)
 

src/include/lwip/opt.h

@@ -963,11 +963,11 @@
 
 /*
    ----------------------------------
-   ---------- IGMP options ----------
+   ----- Multicast/IGMP options -----
    ----------------------------------
 */
 /**
- * LWIP_IGMP==1: Turn on IGMP module. 
+ * LWIP_IGMP==1: Turn on IGMP module.
  */
 #ifndef LWIP_IGMP
 #define LWIP_IGMP                       0
@@ -977,6 +977,14 @@
 #define LWIP_IGMP                       0
 #endif
 
+/**
+ * LWIP_MULTICAST_TX_OPTIONS==1: Enable multicast TX support like the socket options
+ * IP_MULTICAST_TTL/IP_MULTICAST_IF/IP_MULTICAST_LOOP
+ */
+#ifndef LWIP_MULTICAST_TX_OPTIONS
+#define LWIP_MULTICAST_TX_OPTIONS       LWIP_IGMP
+#endif
+
 /*
    ----------------------------------
    ---------- DNS options -----------

src/include/lwip/sockets.h

@@ -253,15 +253,21 @@ struct linger {
 #endif /* LWIP_UDP && LWIP_UDPLITE*/
 
 
-#if LWIP_IGMP
+#if LWIP_MULTICAST_TX_OPTIONS
 /*
  * Options and types for UDP multicast traffic handling
  */
-#define IP_ADD_MEMBERSHIP  3
-#define IP_DROP_MEMBERSHIP 4
 #define IP_MULTICAST_TTL   5
 #define IP_MULTICAST_IF    6
 #define IP_MULTICAST_LOOP  7
+#endif /* LWIP_MULTICAST_TX_OPTIONS */
+
+#if LWIP_IGMP
+/*
+ * Options and types related to multicast membership
+ */
+#define IP_ADD_MEMBERSHIP  3
+#define IP_DROP_MEMBERSHIP 4
 
 typedef struct ip_mreq {
     struct in_addr imr_multiaddr; /* IP multicast address of group */

src/include/lwip/udp.h

@@ -100,12 +100,12 @@ struct udp_pcb {
   /** ports are in host byte order */
   u16_t local_port, remote_port;
 
-#if LWIP_IGMP
+#if LWIP_MULTICAST_TX_OPTIONS
   /** outgoing network interface for multicast packets */
   ip4_addr_t multicast_ip;
   /** TTL for outgoing multicast packets */
   u8_t mcast_ttl;
-#endif /* LWIP_IGMP */
+#endif /* LWIP_MULTICAST_TX_OPTIONS */
 
 #if LWIP_UDPLITE
   /** used for UDP_LITE only */
@@ -168,12 +168,12 @@ void             udp_init       (void);
 struct udp_pcb * udp_new_ip6(void);
 #endif /* LWIP_IPV6 */
 
-#if LWIP_IGMP
+#if LWIP_MULTICAST_TX_OPTIONS
 #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, value)      do { (pcb)->mcast_ttl = value; } while(0)
 #define udp_get_multicast_ttl(pcb)                 ((pcb)->mcast_ttl)
-#endif /* LWIP_IGMP */
+#endif /* LWIP_MULTICAST_TX_OPTIONS */
 
 #if UDP_DEBUG
 void udp_debug_print(struct udp_hdr *udphdr);