[PATCH] Properly handle unknown ctrl requests in bio implementation

[Denis Kovalchuk]

Hello!

I noticed that serf bio implementation does not properly handle unknown ctrl
requests by returning 1 instead of 0. According to the documentation [1],
the implementation is expected to return 0 for unknown ctrls.

This issue has been discussed in SERF-198 [2]. I would like to propose an
updated and extended patch to solve the issue.

The patch includes:
- The fix for the bio_bucket_ctrl() function.
- Similar fix for the new bio_file_ctrl() function.
- Similar fix for the bio_apr_socket_ctrl() function in the MockHTTP server.

[1] https://www.openssl.org/docs/manmaster/man3/BIO_ctrl.html#NOTES
[2] https://issues.apache.org/jira/browse/SERF-198

Kind Regards,
Denis Kovalchuk

Fix the return value for unknown controls in the BIO control functions.

According to the BIO_ctrl() manual page [1]:

[[[
Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl() operation.
]]]

OpenSSL 3.0 adds support for Kernel TLS and uses new controls to determine if
KTLS is used for sending or receiving:

1) BIO_get_ktls_send()
2) BIO_get_ktls_recv()

These controls return 1 if KTLS is used and 0 if not [2].

As a result, OpenSSL believed that serf BIOs support KTLS and thus handle TLS
header insertion and encryption/decryption in the BIO layer, breaking the use
of HTTPS. This bug was observed in FreeBSD [3].

[1] https://www.openssl.org/docs/manmaster/man3/BIO_ctrl.html#NOTES
[2] https://www.openssl.org/docs/manmaster/man3/BIO_ctrl.html#RETURN-VALUES
[3] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253135

* buckets/ssl_buckets.c
  (bio_bucket_ctrl,
   bio_file_ctrl): Return 0 for unknown controls.

* test/MockHTTPinC/MockHTTP_server.c
  (bio_apr_socket_ctrl): Return 0 for unknown controls.

Index: test/MockHTTPinC/MockHTTP_server.c
===================================================================
--- test/MockHTTPinC/MockHTTP_server.c  (revision 1902209)
+++ test/MockHTTPinC/MockHTTP_server.c  (working copy)
@@ -2339,7 +2339,7 @@ static long bio_apr_socket_ctrl(BIO *bio, int cmd,
             return ssl_ctx->hit_eof;
         default:
             /* abort(); */
-            return 1;
+            return 0;
     }
 }
 
Index: buckets/ssl_buckets.c
===================================================================
--- buckets/ssl_buckets.c       (revision 1902209)
+++ buckets/ssl_buckets.c       (working copy)
@@ -524,7 +524,7 @@ static long bio_bucket_ctrl(BIO *bio, int cmd, lon
         return ctx->hit_eof;
     default:
         /* abort(); */
-        return 1;
+        return 0;
     }
 }
 
@@ -546,7 +546,7 @@ static long bio_file_ctrl(BIO *bio, int cmd, long
             return 0;
     default:
         /* abort(); */
-        return 1;
+        return 0;
     }
 }