Merge pull request #1666 from pguyot/w20/add-support-for-loopback-on-rp2

Add support to connect to loopback address on RP2 platform

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

libs/estdlib/src/socket.erl

@@ -400,7 +400,7 @@ recv0(Socket, Length, Timeout) ->
 
 recv0_nowait(Socket, Length, Ref) ->
     case ?MODULE:nif_recv(Socket, Length) of
-        {error, timeout} ->
+        {error, Reason} when Reason =:= timeout orelse Reason =:= eagain ->
             case ?MODULE:nif_select_read(Socket, Ref) of
                 ok ->
                     {select, {select_info, recv, Ref}};

src/libAtomVM/otp_socket.c

@@ -146,6 +146,7 @@ struct UDPReceivedItem
 
 static err_t tcp_recv_cb(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err);
 static void udp_recv_cb(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port);
+static void tcp_err_cb(void *arg, err_t err);
 
 #endif
 
@@ -620,6 +621,7 @@ static term nif_socket_open(Context *ctx, int argc, term argv[])
         if (rsrc_obj->socket_state & SocketStateTCP) {
             LWIP_BEGIN();
             tcp_arg(rsrc_obj->tcp_pcb, rsrc_obj);
+            tcp_err(rsrc_obj->tcp_pcb, tcp_err_cb);
             tcp_recv(rsrc_obj->tcp_pcb, tcp_recv_cb);
             LWIP_END();
         } else {
@@ -996,6 +998,23 @@ static void udp_recv_cb(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip
         otp_socket_lwip_enqueue(&event);
     } // Otherwise socket was closed.
 }
+
+// LwIP tcpip_try_callback uses queue.
+static void tcpip_try_callback_handler(struct LWIPEvent *event)
+{
+    event->tcpip_try_callback.function(event->tcpip_try_callback.ctx);
+}
+
+int tcpip_try_callback(tcpip_callback_fn function, void *ctx)
+{
+    struct LWIPEvent event;
+    event.handler = tcpip_try_callback_handler;
+    event.tcpip_try_callback.function = function;
+    event.tcpip_try_callback.ctx = ctx;
+    otp_socket_lwip_enqueue(&event);
+    return ERR_OK;
+}
+
 #endif
 
 static term nif_socket_select_read(Context *ctx, int argc, term argv[])
@@ -2639,6 +2658,25 @@ static err_t tcp_connected_cb(void *arg, struct tcp_pcb *tpcb, err_t err)
     } // else: sender died
     return ERR_OK;
 }
+
+static void tcp_err_cb(void *arg, err_t err)
+{
+    UNUSED(err);
+
+    struct SocketResource *rsrc_obj = (struct SocketResource *) arg;
+    struct RefcBinary *rsrc_refc = refc_binary_from_data(rsrc_obj);
+    GlobalContext *global = rsrc_refc->resource_type->global;
+    int32_t target_pid = rsrc_obj->selecting_process_id;
+    rsrc_obj->selecting_process_id = INVALID_PROCESS_ID;
+    rsrc_obj->socket_state = SocketStateTCPConnected;
+    if (target_pid != INVALID_PROCESS_ID) {
+        struct LWIPEvent event;
+        event.handler = trap_answer_closed;
+        event.trap_answer_closed.global = global;
+        event.trap_answer_closed.target_pid = target_pid;
+        otp_socket_lwip_enqueue(&event);
+    } // else: sender died
+}
 #endif
 
 static term nif_socket_connect(Context *ctx, int argc, term argv[])
@@ -2741,6 +2779,9 @@ static term nif_socket_connect(Context *ctx, int argc, term argv[])
     LWIP_END();
 
     if (UNLIKELY(err != ERR_OK)) {
+        if (err == ERR_USE || err == ERR_RTE) {
+            return make_error_tuple(CLOSED_ATOM, ctx);
+        }
         RAISE_ERROR(OUT_OF_MEMORY_ATOM);
     }
     if (rsrc_obj->socket_state & SocketStateUDP) {

src/libAtomVM/otp_socket.h

@@ -131,6 +131,11 @@ struct LWIPEvent
         {
             struct SocketResource *rsrc_obj;
         } finalize_close;
+        struct
+        {
+            tcpip_callback_fn function;
+            void *ctx;
+        } tcpip_try_callback;
         // Used by otp_net
         struct
         {

src/platforms/rp2/src/lib/lwipopts.h

@@ -107,4 +107,16 @@ void sntp_set_system_time_us(unsigned long sec, unsigned long usec);
 #define SNTP_SET_SYSTEM_TIME_US(sec, usec) sntp_set_system_time_us(sec, usec)
 
 #define TCP_LISTEN_BACKLOG 1
+
+#define LWIP_NETIF_LOOPBACK 1
+#define LWIP_NETIF_LOOPBACK_MULTITHREADING 1
+#define LWIP_HAVE_LOOPIF 0
+
+// To support loopback, we implement our own version of tcpip_try_callback that
+// enqueues a call to netif_poll.
+struct netif;
+void netif_poll(struct netif *netif);
+typedef void (*tcpip_callback_fn)(void *ctx);
+int tcpip_try_callback(tcpip_callback_fn function, void *ctx);
+
 #endif /* __LWIPOPTS_H__ */