Add smtp client example

src/event.h

@@ -13,6 +13,7 @@ enum {
   MG_EV_RESOLVE,     // Host name is resolved        NULL
   MG_EV_CONNECT,     // Connection established       NULL
   MG_EV_ACCEPT,      // Connection accepted          NULL
+  MG_EV_TLS_HS,      // TLS handshake succeeded      NULL
   MG_EV_READ,        // Data received from socket    long *bytes_read
   MG_EV_WRITE,       // Data written to socket       long *bytes_written
   MG_EV_CLOSE,       // Connection closed            NULL

src/tls_mbed.c

@@ -48,6 +48,7 @@ void mg_tls_handshake(struct mg_connection *c) {
   if (rc == 0) {  // Success
     MG_DEBUG(("%lu success", c->id));
     c->is_tls_hs = 0;
+    mg_call(c, MG_EV_TLS_HS, NULL);
   } else if (rc == MBEDTLS_ERR_SSL_WANT_READ ||
              rc == MBEDTLS_ERR_SSL_WANT_WRITE) {  // Still pending
     MG_VERBOSE(("%lu pending, %d%d %d (-%#x)", c->id, c->is_connecting,
@@ -185,7 +186,7 @@ size_t mg_tls_pending(struct mg_connection *c) {
 long mg_tls_recv(struct mg_connection *c, void *buf, size_t len) {
   struct mg_tls *tls = (struct mg_tls *) c->tls;
   long n = mbedtls_ssl_read(&tls->ssl, (unsigned char *) buf, len);
-  if (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE) 
+  if (n == MBEDTLS_ERR_SSL_WANT_READ || n == MBEDTLS_ERR_SSL_WANT_WRITE)
     return MG_IO_WAIT;
   if (n <= 0) return MG_IO_ERR;
   return n;

src/tls_openssl.c

@@ -116,6 +116,7 @@ void mg_tls_handshake(struct mg_connection *c) {
   if (rc == 1) {
     MG_DEBUG(("%lu success", c->id));
     c->is_tls_hs = 0;
+    mg_call(c, MG_EV_TLS_HS, NULL);
   } else {
     int code = mg_tls_err(tls, rc);
     if (code != 0) mg_error(c, "tls hs: rc %d, err %d", rc, code);