fix half_close: send CLOSE from proxy_poll_cb when no pending data, shutdown not close on exit

src/remote_proxy.c

@@ -232,7 +232,8 @@ void remote_proxy_handle_close(struct UTUN_INSTANCE* inst, uint64_t stream_id) {
     while (*prev) {
         struct remote_proxy_conn* rc = *prev;
         if (rc->stream_id == stream_id) {
-            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "remote_proxy: close stream=%016llx", (unsigned long long)stream_id);
+            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "RP CLOSE stream=%016llx", (unsigned long long)stream_id);
+            if (rc->sock != SOCKET_INVALID && rc->connected == 1) shutdown(rc->sock, SHUT_WR);
             *prev = rc->next; rp_conn_free(rc); return;
         }
         prev = &rc->next;

src/tcp_proxy.c

@@ -263,11 +263,6 @@ static err_t proxy_recv_cb(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t
     if (p == NULL || err != LERR_OK) {
         DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY FIN stream=%016llx tun=1 active=%d", (unsigned long long)(pc->remote_stream_id ? pc->remote_stream_id : 0), pc->active);
         pc->closing_tun = 1;
-        if (pc->closing_rem) {
-            DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY CLOSE stream=%016llx tun=1 rem=1 (recv)", (unsigned long long)pc->remote_stream_id);
-        } else if (pc->transport) {
-            pc->transport->ops->close(pc->transport);
-        }
         return LERR_OK;
     }
 
@@ -314,6 +309,11 @@ static void proxy_err_cb(void *arg, err_t err) {
 static err_t proxy_poll_cb(void *arg, struct tcp_pcb *pcb) {
     struct proxy_conn *pc = (struct proxy_conn *)arg;
     if (!pc) return LERR_OK;
+    if (pc->closing_tun && !pc->closing_rem && pc->transport && pc->transport_to_uip
+        && queue_entry_count(pc->transport_to_uip) == 0) {
+        DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY CLOSE stream=%016llx tun=1 (no pending)", (unsigned long long)pc->remote_stream_id);
+        pc->transport->ops->close(pc->transport);
+    }
     if (pc->closing_tun && pc->closing_rem && pc->pcb) {
         DEBUG_INFO(DEBUG_CATEGORY_SOCKET, "PROXY CLOSE stream=%016llx tun=1 rem=1", (unsigned long long)pc->remote_stream_id);
         struct tcp_pcb *save = pc->pcb;