net: context: Add helpers for figuring out local endpoint address

We usually cannot use context->local for established TCP connections
because the local address is not updated for TCP if we are bound to
any address. So create helper that try to figure out the end point
addresses.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>

Author: jukkar

subsys/net/ip/net_context.c

@@ -3181,6 +3181,51 @@ int net_context_get_option(struct net_context *context,
 	return ret;
 }
 
+int net_context_get_local_addr(struct net_context *ctx,
+			       struct sockaddr *addr,
+			       socklen_t *addrlen)
+{
+	if (ctx == NULL || addr == NULL || addrlen == NULL) {
+		return -EINVAL;
+	}
+
+	if (IS_ENABLED(CONFIG_NET_TCP) &&
+	    net_context_get_type(ctx) == SOCK_STREAM) {
+		return net_tcp_endpoint_copy(ctx, addr, NULL, addrlen);
+	}
+
+	if (IS_ENABLED(CONFIG_NET_UDP) && net_context_get_type(ctx) == SOCK_DGRAM) {
+		socklen_t newlen;
+
+		if (IS_ENABLED(CONFIG_NET_IPV4) && ctx->local.family == AF_INET) {
+			newlen = MIN(*addrlen, sizeof(struct sockaddr_in));
+
+			net_sin(addr)->sin_family = AF_INET;
+			net_sin(addr)->sin_port = net_sin_ptr(&ctx->local)->sin_port;
+			memcpy(&net_sin(addr)->sin_addr,
+			       net_sin_ptr(&ctx->local)->sin_addr,
+			       sizeof(struct in_addr));
+
+		} else if (IS_ENABLED(CONFIG_NET_IPV6) && ctx->local.family == AF_INET6) {
+			newlen = MIN(*addrlen, sizeof(struct sockaddr_in6));
+
+			net_sin6(addr)->sin6_family = AF_INET6;
+			net_sin6(addr)->sin6_port = net_sin6_ptr(&ctx->local)->sin6_port;
+			memcpy(&net_sin6(addr)->sin6_addr,
+			       net_sin6_ptr(&ctx->local)->sin6_addr,
+			       sizeof(struct in6_addr));
+		} else {
+			return -EAFNOSUPPORT;
+		}
+
+		*addrlen = newlen;
+
+		return 0;
+	}
+
+	return -ENOPROTOOPT;
+}
+
 void net_context_foreach(net_context_cb_t cb, void *user_data)
 {
 	int i;

subsys/net/ip/net_private.h

@@ -81,6 +81,9 @@ extern bool net_context_is_recv_pktinfo_set(struct net_context *context);
 extern void net_pkt_init(void);
 extern void net_tc_tx_init(void);
 extern void net_tc_rx_init(void);
+int net_context_get_local_addr(struct net_context *context,
+			       struct sockaddr *addr,
+			       socklen_t *addrlen);
 #else
 static inline void net_context_init(void) { }
 static inline void net_pkt_init(void) { }
@@ -106,6 +109,17 @@ static inline bool net_context_is_recv_pktinfo_set(struct net_context *context)
 	ARG_UNUSED(context);
 	return false;
 }
+
+static inline int net_context_get_local_addr(struct net_context *context,
+					     struct sockaddr *addr,
+					     socklen_t *addrlen)
+{
+	ARG_UNUSED(context);
+	ARG_UNUSED(addr);
+	ARG_UNUSED(addrlen);
+
+	return -ENOTSUP;
+}
 #endif
 
 #if defined(CONFIG_NET_NATIVE)

subsys/net/ip/tcp.c

@@ -239,6 +239,51 @@ static int tcp_endpoint_set(union tcp_endpoint *ep, struct net_pkt *pkt,
 	return ret;
 }
 
+int net_tcp_endpoint_copy(struct net_context *ctx,
+			  struct sockaddr *local,
+			  struct sockaddr *peer,
+			  socklen_t *addrlen)
+{
+	const struct tcp *conn = ctx->tcp;
+	socklen_t newlen = ctx->local.family == AF_INET ?
+		sizeof(struct sockaddr_in) :
+		sizeof(struct sockaddr_in6);
+
+	if (local != NULL) {
+		/* If we are connected, then get the address we are actually
+		 * using, otherwise get the address we are bound as these might
+		 * be different if we are bound to any address.
+		 */
+		if (conn->state < TCP_ESTABLISHED) {
+			if (IS_ENABLED(CONFIG_NET_IPV4) && ctx->local.family == AF_INET) {
+				memcpy(&net_sin(local)->sin_addr,
+				       net_sin_ptr(&ctx->local)->sin_addr,
+				       sizeof(struct in_addr));
+				net_sin(local)->sin_port = net_sin_ptr(&ctx->local)->sin_port;
+				net_sin(local)->sin_family = AF_INET;
+			} else if (IS_ENABLED(CONFIG_NET_IPV4) && ctx->local.family == AF_INET6) {
+				memcpy(&net_sin6(local)->sin6_addr,
+				       net_sin6_ptr(&ctx->local)->sin6_addr,
+				       sizeof(struct in6_addr));
+				net_sin6(local)->sin6_port = net_sin6_ptr(&ctx->local)->sin6_port;
+				net_sin6(local)->sin6_family = AF_INET6;
+				net_sin6(local)->sin6_scope_id =
+					net_sin6_ptr(&ctx->local)->sin6_scope_id;
+			} else {
+				return -EINVAL;
+			}
+		} else {
+			memcpy(local, &conn->src.sa, newlen);
+		}
+	}
+
+	if (peer != NULL) {
+		memcpy(local, &conn->dst.sa, newlen);
+	}
+
+	return 0;
+}
+
 static const char *tcp_flags(uint8_t flags)
 {
 #define BUF_SIZE 25 /* 6 * 4 + 1 */

subsys/net/ip/tcp_internal.h

@@ -448,6 +448,21 @@ static inline void net_tcp_reply_rst(struct net_pkt *pkt)
 }
 #endif
 
+/**
+ * @brief Get the TCP connection endpoint information.
+ *
+ * @param context Network context
+ * @param local TCP connection local socket information is copied here
+ * @param peer TCP connection peer socket information is copied here
+ * @param addrlen Size of the sockaddr struct. Copied size is returned.
+ *
+ * @return <0 if there was an error, 0 if ok
+ */
+int net_tcp_endpoint_copy(struct net_context *ctx,
+			  struct sockaddr *local,
+			  struct sockaddr *peer,
+			  socklen_t *addrlen);
+
 #ifdef __cplusplus
 }
 #endif