Move some useful internal logic from recvfrom.c and udp_callback.c and put them in ip.h where they can be used more generally

3 files changed, 60 insertions, 21 deletions

diff --git a/nuttx/include/nuttx/net/ip.h b/nuttx/include/nuttx/net/ip.h
index 3bb221f10..0f80cd2e1 100644
--- a/nuttx/include/nuttx/net/ip.h
+++ b/nuttx/include/nuttx/net/ip.h
@@ -328,17 +328,50 @@ EXTERN const net_ipv6addr_t g_ipv6_llnetmask;   /* Netmask for local link addres
   } while (0)
 
 /****************************************************************************
+ * Macro: ip6_map_ipv4addr
+ *
+ * Description:
+ *   Hybrid dual-stack IPv6/IPv4 implementations recognize a special class
+ *   of addresses, the IPv4-mapped IPv6 addresses. These addresses consist
+ *   of:
+ *
+ *     1. An 80-bit prefix of zeros,
+ *     2. Te next 16 bits are one, and
+ *     3. he remaining, least-significant 32 bits contain the IPv4 address.
+ *
+ *   This macro encodes an IPv4 address in an IPv6 address in this fashion.
+ *
+ * Input Parameters:
+ *   ipv4addr - The IPv4 address to be mapped (scalar)
+ *   ipv6addr - The IPv6 address in which to map the IPv4 address (array)
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+#define ip6_map_ipv4addr(ipv4addr, ipv6addr) \
+  do \
+    { \
+      memset(ipv6addr, 0, 5 * sizeof(uint16_t)); \
+      ipv6addr[5] = 0xffff; \
+      ipv6addr[6] = (uint16_t)((uint32_t)ip4addr >> 16); \
+      ipv6addr[7] = (uint16_t)ip4addr & 0xffff; \
+    } \
+  while (0)
+
+/****************************************************************************
  * Macro: ip6_get_ipv4addr
  *
  * Description:
- *   Decode an encoded IPv4 address.
+ *   Decode an IPv4-mapped IPv6 address.
  *
  * Input Parameters:
- *   ipv6addr - The IPv6 address (net_ipv6addr_t) containing the encoded
+ *   ipv6addr - The IPv6 address (net_ipv6addr_t array) containing the mapped
  *     IPv4 address
  *
  * Returned Value:
- *   The decode IPv4 addreses (in_addr_t)
+ *   The decoded IPv4 address (scalar in_addr_t)
  *
  ****************************************************************************/
 
@@ -352,13 +385,13 @@ EXTERN const net_ipv6addr_t g_ipv6_llnetmask;   /* Netmask for local link addres
  * Macro: ip6_is_ipv4addr
  *
  * Description:
- *   Test if an IPv6 is an encoded IPv4 address.
+ *   Test if an IPv6 is an IPv4-mapped IPv6 address.
  *
  * Input Parameters:
  *   ipv6addr - The IPv6 address to be tested
  *
  * Returned Value:
- *   True is returned if ipv6addr holds an encoded IPv4 address.
+ *   True is returned if ipv6addr holds a mapped IPv4 address.
  *
  ****************************************************************************/
 
diff --git a/nuttx/net/socket/recvfrom.c b/nuttx/net/socket/recvfrom.c
index 3ca7b125e..13d42061a 100644
--- a/nuttx/net/socket/recvfrom.c
+++ b/nuttx/net/socket/recvfrom.c
@@ -971,20 +971,23 @@ static inline void recvfrom_udpsender(struct net_driver_s *dev, struct recvfrom_
           FAR struct udp_conn_s *conn = (FAR struct udp_conn_s*)pstate->rf_sock->s_conn;
           FAR struct sockaddr_in6 *infrom6 = (FAR struct sockaddr_in6 *)infrom;
 
+          /* Hybrid dual-stack IPv6/IPv4 implementations recognize a special
+           * class of addresses, the IPv4-mapped IPv6 addresses.
+           */
+
           if (conn->domain == PF_INET6)
             {
+              in_addr_t ipv4addr;
+
+              /* Encode the IPv4 address as an IPv4-mapped IPv6 address */
+
               infrom6->sin6_family = AF_INET6;
               infrom6->sin6_port = udp->srcport;
               *fromlen = sizeof(struct sockaddr_in6);
 
-              memset(infrom6->sin6_addr.s6_addr, 0,
-                     sizeof(infrom6->sin6_addr.s6_addr) - sizeof(in_addr_t));
-
-              infrom6->sin6_addr.s6_addr[10] = 0xff;
-              infrom6->sin6_addr.s6_addr[11] = 0xff;
-
-              memcpy(&infrom6->sin6_addr.s6_addr[12], ipv4->srcipaddr
-                     sizeof(in_addr_t));
+              ipv4addr = net_ip4addr_conv32(ipv4->srcipaddr);
+              ip6_map_ipv4addr(ipv4addr,
+                               (net_ipv6addr_t)src_addr6.sin6_addr.s6_addr16);
             }
           else
 #endif
diff --git a/nuttx/net/udp/udp_callback.c b/nuttx/net/udp/udp_callback.c
index 583f348af..807c12446 100644
--- a/nuttx/net/udp/udp_callback.c
+++ b/nuttx/net/udp/udp_callback.c
@@ -133,19 +133,22 @@ static uint16_t udp_datahandler(FAR struct net_driver_s *dev, FAR struct udp_con
       FAR struct ipv4_hdr_s *ipv4 = IPv4BUF;
 
 #ifdef CONFIG_NET_IPv6
+      /* Hybrid dual-stack IPv6/IPv4 implementations recognize a special
+       * class of addresses, the IPv4-mapped IPv6 addresses.
+       */
+
       if (conn->domain == PF_INET6)
         {
-          src_addr6.sin6_family = AF_INET6;
-          src_addr6.sin6_port = udp->srcport;
+          in_addr_t ipv4addr;
 
-          memset(src_addr6.sin6_addr.s6_addr, 0,
-                 sizeof(src_addr6.sin6_addr.s6_addr) - sizeof(in_addr_t));
+          /* Encode the IPv4 address as an IPv-mapped IPv6 address */
 
-          src_addr6.sin6_addr.s6_addr[10] = 0xff;
-          src_addr6.sin6_addr.s6_addr[11] = 0xff;
+          src_addr6.sin6_family = AF_INET6;
+          src_addr6.sin6_port = udp->srcport;
 
-          memcpy(&src_addr6.sin6_addr.s6_addr[12], ipv4->srcipaddr,
-                 sizeof(in_addr_t));
+          ipv4addr = net_ip4addr_conv32(ipv4->srcipaddr);
+          ip6_map_ipv4addr(ipv4addr,
+                           (net_ipv6addr_t)src_addr6.sin6_addr.s6_addr16);
 
           src_addr_size = sizeof(src_addr6);
           src_addr = &src_addr6;