The fix for PR#1949 unfortunately broke cases where the BIO_CTRL_WPENDING

ctrl is incorrectly implemented (e.g. some versions of Apache). As a workaround
call both BIO_CTRL_INFO and BIO_CTRL_WPENDING if it returns zero. This should
both address the original bug and retain compatibility with the old behaviour.

diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index 00fc2616b77a472a58373477a6d0482231648d0e..c8bed170b5e409d183be6cf062c4724109e59d03 100644 (file)
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -484,7 +484,21 @@ int ssl3_accept(SSL *s)
                
                case SSL3_ST_SW_FLUSH:
                        /* number of bytes to be flushed */
-                       num1=BIO_ctrl(s->wbio,BIO_CTRL_WPENDING,0,NULL);
+                       /* This originally and incorrectly called BIO_CTRL_INFO
+                        * The reason why this is wrong is mentioned in PR#1949.
+                        * Unfortunately, as suggested in that bug some
+                        * versions of Apache unconditionally return 0
+                        * for BIO_CTRL_WPENDING meaning we don't correctly
+                        * flush data and some operations, like renegotiation,
+                        * don't work. Other software may also be affected so
+                        * call BIO_CTRL_INFO to retain compatibility with
+                        * previous behaviour and BIO_CTRL_WPENDING if we
+                        * get zero to address the PR#1949 case.
+                        */
+
+                       num1=BIO_ctrl(s->wbio,BIO_CTRL_INFO,0,NULL);
+                       if (num1 == 0)
+                               num1=BIO_ctrl(s->wbio,BIO_CTRL_WPENDING,0,NULL);
                        if (num1 > 0)
                                {
                                s->rwstate=SSL_WRITING;