axtls: call ssl_read repeatedly

Perform more work in between sleeps. This is work around the
fact that axtls does not expose any knowledge about when work needs
to be performed. Depending on connection and how often perform is
being called this can save ~25% of time on SSL handshakes (measured
on 20ms latency connection calling perform roughly every 10ms).

1 files changed, 9 insertions, 8 deletions

diff --git a/lib/vtls/axtls.c b/lib/vtls/axtls.c
index d5d6db2ff..73602a4e7 100644
--- a/lib/vtls/axtls.c
+++ b/lib/vtls/axtls.c
@@ -398,6 +398,7 @@ CURLcode Curl_axtls_connect_nonblocking(
 {
   CURLcode conn_step;
   int ssl_fcn_return;
+  int i;
 
  *done = FALSE;
   /* connectdata is calloc'd and connecting_state is only changed in this
@@ -414,14 +415,14 @@ CURLcode Curl_axtls_connect_nonblocking(
   if(conn->ssl[sockindex].connecting_state == ssl_connect_2) {
     /* Check to make sure handshake was ok. */
     if(ssl_handshake_status(conn->ssl[sockindex].ssl) != SSL_OK) {
-      ssl_fcn_return = ssl_read(conn->ssl[sockindex].ssl, NULL);
-      if(ssl_fcn_return < 0) {
-        Curl_axtls_close(conn, sockindex);
-        ssl_display_error(ssl_fcn_return); /* goes to stdout. */
-        return map_error_to_curl(ssl_fcn_return);
-      }
-      else {
-        return CURLE_OK; /* Return control to caller for retries */
+      for(i=0; i<5; i++) {
+        ssl_fcn_return = ssl_read(conn->ssl[sockindex].ssl, NULL);
+        if(ssl_fcn_return < 0) {
+          Curl_axtls_close(conn, sockindex);
+          ssl_display_error(ssl_fcn_return); /* goes to stdout. */
+          return map_error_to_curl(ssl_fcn_return);
+        }
+        return CURLE_OK;
       }
     }
     infof (conn->data, "handshake completed successfully\n");