Implemented timeout on send (TCP only, bug #33820)

src/include/lwip/api.h

@@ -180,6 +180,11 @@ struct netconn {
 #if LWIP_SOCKET
   int socket;
 #endif /* LWIP_SOCKET */
+#if LWIP_SO_SNDTIMEO
+  /** timeout to wait for sending data (which means enqueueing data for sending
+      in internal buffers) */
+  s32_t send_timeout;
+#endif /* LWIP_SO_RCVTIMEO */
 #if LWIP_SO_RCVTIMEO
   /** timeout to wait for new data to be received
       (or connections to arrive for listening netconns) */
@@ -299,6 +304,12 @@ err_t   netconn_gethostbyname(const char *name, ip_addr_t *addr);
 /** TCP: Get the no-auto-recved status of netconn calls (see NETCONN_FLAG_NO_AUTO_RECVED) */
 #define netconn_get_noautorecved(conn)        (((conn)->flags & NETCONN_FLAG_NO_AUTO_RECVED) != 0)
 
+#if LWIP_SO_SNDTIMEO
+/** Set the send timeout in milliseconds */
+#define netconn_set_sendtimeout(conn, timeout)      ((conn)->send_timeout = (timeout))
+/** Get the send timeout in milliseconds */
+#define netconn_get_sendtimeout(conn)               ((conn)->send_timeout)
+#endif /* LWIP_SO_SNDTIMEO */
 #if LWIP_SO_RCVTIMEO
 /** Set the receive timeout in milliseconds */
 #define netconn_set_recvtimeout(conn, timeout)      ((conn)->recv_timeout = (timeout))

src/include/lwip/api_msg.h

@@ -89,6 +89,9 @@ struct api_msg_msg {
       const void *dataptr;
       size_t len;
       u8_t apiflags;
+#if LWIP_SO_SNDTIMEO
+      u32_t time_started;
+#endif /* LWIP_SO_SNDTIMEO */
     } w;
     /** used for do_recv */
     struct {

src/include/lwip/opt.h

@@ -1434,6 +1434,14 @@
 #define LWIP_TCP_KEEPALIVE              0
 #endif
 
+/**
+ * LWIP_SO_SNDTIMEO==1: Enable send timeout for sockets/netconns and
+ * SO_SNDTIMEO processing.
+ */
+#ifndef LWIP_SO_SNDTIMEO
+#define LWIP_SO_SNDTIMEO                0
+#endif
+
 /**
  * LWIP_SO_RCVTIMEO==1: Enable receive timeout for sockets/netconns and
  * SO_RCVTIMEO processing.