altcp_tls_mbedtls: tcp_out: Fix handshake when called from u-boot

When using the http-client LWIP app in U-Boot (OS_SYS=0), the handshake
fails because LWIP doesn't send TCP packets after it initiates.

Signed-off-by: Javier Tia <javier.tia@linaro.org>

Author: jetm

src/apps/altcp_tls/altcp_tls_mbedtls.c

@@ -1292,6 +1292,8 @@ altcp_mbedtls_bio_send(void *ctx, const unsigned char *dataptr, size_t size)
   while (size_left) {
     u16_t write_len = (u16_t)LWIP_MIN(size_left, 0xFFFF);
     err_t err = altcp_write(conn->inner_conn, (const void *)dataptr, write_len, apiflags);
+    /* try to send data... */
+    altcp_output(conn->inner_conn);
     if (err == ERR_OK) {
       written += write_len;
       size_left -= write_len;

src/core/tcp_out.c

@@ -1255,14 +1255,6 @@ tcp_output(struct tcp_pcb *pcb)
   LWIP_ASSERT("don't call tcp_output for listen-pcbs",
               pcb->state != LISTEN);
 
-  /* First, check if we are invoked by the TCP input processing
-     code. If so, we do not output anything. Instead, we rely on the
-     input processing code to call us when input processing is done
-     with. */
-  if (tcp_input_pcb == pcb) {
-    return ERR_OK;
-  }
-
   wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
 
   seg = pcb->unsent;
@@ -2039,7 +2031,7 @@ tcp_rst(const struct tcp_pcb *pcb, u32_t seqno, u32_t ackno,
         u16_t local_port, u16_t remote_port)
 {
   struct pbuf *p;
-  
+
   p = tcp_rst_common(pcb, seqno, ackno, local_ip, remote_ip, local_port, remote_port);
   if (p != NULL) {
     tcp_output_control_segment(pcb, p, local_ip, remote_ip);