From 7744f0d543141c125aca907bc995cc29b7843ff9 Mon Sep 17 00:00:00 2001
From: Eric Blankenhorn <eric@wolfssl.com>
Date: Thu, 13 Aug 2020 15:33:20 -0500
Subject: [PATCH] Check for non-blocking return code in BioSend

---
 src/wolfio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wolfio.c b/src/wolfio.c
index 95bb6171f..3c060c6a6 100644
--- a/src/wolfio.c
+++ b/src/wolfio.c
@@ -181,7 +181,7 @@ int BioSend(WOLFSSL* ssl, char *buf, int sz, void *ctx)
     if (ssl->biowr->method && ssl->biowr->method->writeCb) {
         WOLFSSL_MSG("Calling custom biowr");
         sent = ssl->biowr->method->writeCb(ssl->biowr, buf, sz);
-        if (sent < 0) {
+        if ((sent < 0) && (sent != WOLFSSL_CBIO_ERR_WANT_WRITE)) {
             return WOLFSSL_CBIO_ERR_GENERAL;
         }
         return sent;