Add multicast implementation for UDPSocket

Author: kegilbert

features/FEATURE_LWIP/lwip-interface/lwip_stack.c

@@ -34,6 +34,7 @@
 #include "lwip/mld6.h"
 #include "lwip/dns.h"
 #include "lwip/udp.h"
+#include "lwip_errno.h"
 #include "netif/lwip_ethernet.h"
 #include "emac_api.h"
 #include "ppp_lwip.h"
@@ -980,6 +981,25 @@ static nsapi_size_or_error_t mbed_lwip_socket_recvfrom(nsapi_stack_t *stack, nsa
     return recv;
 }
 
+static nsapi_error_t nsapi_addr_to_ip_addr(ip_addr_t *lwip_ip, nsapi_addr_t *nsapi_addr_ip) {
+    struct in_addr inet_addr_convert;
+    // nsapi_addr_t stores IP address in byte array
+    // Convert byte aray -> uint32_t for lwip inet IP representation
+    ip_addr_t multiaddr_ip;
+    if (!convert_mbed_addr_to_lwip(&multiaddr_ip, nsapi_addr_ip)) {
+        return NSAPI_ERROR_PARAMETER;
+    }
+
+    inet_addr_convert.s_addr = multiaddr_ip.addr;
+
+#if LWIP_IPV4
+    // LWIP inet IP representation (in_addr) to ip_addr_t, both structs containing
+    // uint32_t, this step just remaps the ip address for the igmp calls
+    lwip_ip->addr = inet_addr_convert.s_addr;
+#endif
+    return NSAPI_ERROR_OK;
+}
+
 static nsapi_error_t mbed_lwip_setsockopt(nsapi_stack_t *stack, nsapi_socket_t handle, int level, int optname, const void *optval, unsigned optlen)
 {
     struct lwip_socket *s = (struct lwip_socket *)handle;
@@ -1023,6 +1043,36 @@ static nsapi_error_t mbed_lwip_setsockopt(nsapi_stack_t *stack, nsapi_socket_t h
             }
             return 0;
 
+        case NSAPI_ADD_MEMBERSHIP:
+        case NSAPI_DROP_MEMBERSHIP: {
+#if LWIP_IPV6
+            return NSAPI_ERROR_UNSUPPORTED; 
+#else
+            if (optlen != sizeof(nsapi_ip_mreq_t)) {
+                return NSAPI_ERROR_UNSUPPORTED;
+            }
+
+            err_t igmp_err;
+            nsapi_ip_mreq_t *imr = (nsapi_ip_mreq_t *)optval;
+
+            ip_addr_t if_addr;
+            ip_addr_t multi_addr;
+
+            nsapi_addr_to_ip_addr(&multi_addr, &imr->imr_multiaddr);
+            nsapi_addr_to_ip_addr(&if_addr, &imr->imr_interface);
+
+            if (optname == NSAPI_ADD_MEMBERSHIP) {
+                igmp_err = igmp_joingroup(&if_addr, &multi_addr);
+            } else {
+                igmp_err = igmp_leavegroup(&if_addr, &multi_addr);
+            }
+            if (igmp_err != ERR_OK) {
+                return EADDRNOTAVAIL;
+            }
+            return 0;
+#endif
+         }
+
         default:
             return NSAPI_ERROR_UNSUPPORTED;
     }

features/netsocket/UDPSocket.cpp

@@ -33,6 +33,17 @@ nsapi_protocol_t UDPSocket::get_proto()
     return NSAPI_UDP;
 }
 
+int UDPSocket::join_multicast_group(const SocketAddress &address)
+{
+    nsapi_ip_mreq_t mreq;
+
+    // Set up group address
+    mreq.imr_multiaddr = address.get_addr();
+    mreq.imr_interface = SocketAddress().get_addr();   // 0.0.0.0 INADDR_ANY
+
+    return this->setsockopt(0, NSAPI_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+}
+
 nsapi_size_or_error_t UDPSocket::sendto(const char *host, uint16_t port, const void *data, nsapi_size_t size)
 {
     SocketAddress address;

features/netsocket/UDPSocket.h

@@ -56,6 +56,13 @@ class UDPSocket : public Socket {
      */
     virtual ~UDPSocket();
 
+    /** Subscribes to an IP multicast group
+     *
+     * @param address   Multicast group IP address
+     * @return          Negative error code on failure 
+     */
+    int join_multicast_group(const SocketAddress &address);
+
     /** Send a packet over a UDP socket
      *
      *  Sends data to the specified address specified by either a domain name

features/netsocket/nsapi_types.h

@@ -158,7 +158,7 @@ typedef void *nsapi_socket_t;
 /** Enum of socket protocols
  *
  *  The socket protocol specifies a particular protocol to
- *  be used with a newly created socket. 
+ *  be used with a newly created socket.
  *
  *  @enum nsapi_protocol
  */
@@ -207,13 +207,15 @@ typedef enum nsapi_socket_level {
  *  @enum nsapi_socket_option
  */
 typedef enum nsapi_socket_option {
-    NSAPI_REUSEADDR, /*!< Allow bind to reuse local addresses */
-    NSAPI_KEEPALIVE, /*!< Enables sending of keepalive messages */
-    NSAPI_KEEPIDLE,  /*!< Sets timeout value to initiate keepalive */
-    NSAPI_KEEPINTVL, /*!< Sets timeout value for keepalive */
-    NSAPI_LINGER,    /*!< Keeps close from returning until queues empty */
-    NSAPI_SNDBUF,    /*!< Sets send buffer size */
-    NSAPI_RCVBUF,    /*!< Sets recv buffer size */
+    NSAPI_REUSEADDR,         /*!< Allow bind to reuse local addresses */
+    NSAPI_KEEPALIVE,         /*!< Enables sending of keepalive messages */
+    NSAPI_KEEPIDLE,          /*!< Sets timeout value to initiate keepalive */
+    NSAPI_KEEPINTVL,         /*!< Sets timeout value for keepalive */
+    NSAPI_LINGER,            /*!< Keeps close from returning until queues empty */
+    NSAPI_SNDBUF,            /*!< Sets send buffer size */
+    NSAPI_RCVBUF,            /*!< Sets recv buffer size */
+    NSAPI_ADD_MEMBERSHIP,    /*!< Add membership to multicast address */
+    NSAPI_DROP_MEMBERSHIP,   /*!< Drop membership to multicast address */
 } nsapi_socket_option_t;
 
 /* Backwards compatibility - previously didn't distinguish stack and socket options */
@@ -254,6 +256,13 @@ typedef struct nsapi_stack {
     unsigned _stack_buffer[16];
 } nsapi_stack_t;
 
+/** nsapi_ip_mreq structure
+ */
+typedef struct nsapi_ip_mreq {
+    nsapi_addr_t imr_multiaddr; /* IP multicast address of group */
+    nsapi_addr_t imr_interface; /* local IP address of interface */
+} nsapi_ip_mreq_t;
+
 /** nsapi_stack_api structure
  *
  *  Common api structure for network stack operations. A network stack
@@ -275,9 +284,9 @@ typedef struct nsapi_stack_api
      *
      *  The hostname may be either a domain name or an IP address. If the
      *  hostname is an IP address, no network transactions will be performed.
-     *  
+     *
      *  If no stack-specific DNS resolution is provided, the hostname
-     *  will be resolve using a UDP socket on the stack. 
+     *  will be resolve using a UDP socket on the stack.
      *
      *  @param stack    Stack handle
      *  @param addr     Destination for the host IP address
@@ -322,7 +331,7 @@ typedef struct nsapi_stack_api
      *  @param optval   Destination for option value
      *  @param optlen   Length of the option value
      *  @return         0 on success, negative error code on failure
-     */    
+     */
     nsapi_error_t (*getstackopt)(nsapi_stack_t *stack, int level,
             int optname, void *optval, unsigned *optlen);
 
@@ -523,7 +532,7 @@ typedef struct nsapi_stack_api
      *  @param optval   Option value
      *  @param optlen   Length of the option value
      *  @return         0 on success, negative error code on failure
-     */    
+     */
     nsapi_error_t (*setsockopt)(nsapi_stack_t *stack, nsapi_socket_t socket, int level,
             int optname, const void *optval, unsigned optlen);
 
@@ -540,7 +549,7 @@ typedef struct nsapi_stack_api
      *  @param optval   Destination for option value
      *  @param optlen   Length of the option value
      *  @return         0 on success, negative error code on failure
-     */    
+     */
     nsapi_error_t (*getsockopt)(nsapi_stack_t *stack, nsapi_socket_t socket, int level,
             int optname, void *optval, unsigned *optlen);
 } nsapi_stack_api_t;