From fc568ff045e6a8956221c3f095ed8e7200fa5f74 Mon Sep 17 00:00:00 2001
From: zhenhaonong <zhenhaonong@tencent.com>
Date: Fri, 17 Mar 2023 19:53:50 +0800
Subject: [PATCH] Deal with partial writes on SSL write

SSL write may do partial writes in some cases. For example, document
of mbedtls_ssl_write says:
  If the return value is non-negative but less than length, the function
  must be called again with updated arguments: buf + ret, len - ret
  (if ret is the return value) until it returns a value equal to the
  last 'len' argument.

In case of partial writes, we should continue writing the same chain of
buffer, not the next chain.
---
 bufferevent_ssl.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/bufferevent_ssl.c b/bufferevent_ssl.c
index 837b84c4..64c36ae6 100644
--- a/bufferevent_ssl.c
+++ b/bufferevent_ssl.c
@@ -339,15 +339,17 @@ do_write(struct bufferevent_ssl *bev_ssl, int atmost)
 
 	if (n > 8)
 		n = 8;
-	for (i=0; i < n; ++i) {
+	for (i=0; i < n;) {
 		if (bev_ssl->bev.write_suspended)
 			break;
 
 		/* SSL_write will (reasonably) return 0 if we tell it to
 		   send 0 data.  Skip this case so we don't interpret the
 		   result as an error */
-		if (space[i].iov_len == 0)
+		if (space[i].iov_len == 0) {
+			++i;
 			continue;
+		}
 
 		bev_ssl->ssl_ops->clear_error();
 		r = bev_ssl->ssl_ops->write(bev_ssl->ssl, space[i].iov_base,
@@ -360,6 +362,10 @@ do_write(struct bufferevent_ssl *bev_ssl, int atmost)
 			n_written += r;
 			bev_ssl->last_write = -1;
 			bev_ssl->ssl_ops->decrement_buckets(bev_ssl);
+			space[i].iov_base = (unsigned char *)space[i].iov_base + r;
+			space[i].iov_len -= r;
+			if (space[i].iov_len == 0)
+				++i;
 		} else {
 			int err = bev_ssl->ssl_ops->get_error(bev_ssl->ssl, r);
 			bev_ssl->ssl_ops->print_err(err);