s_server: Do not use SSL_sendfile when KTLS is not being used

Fix a bug in `openssl s_server -WWW` where it would attempt to invoke
`SSL_sendfile` if `-ktls -sendfile` was passed on the command line, even
if KTLS has not actually been enabled, for example because it is not
supported by the host. Since `SSL_sendfile` is only supported when KTLS
is actually being used, this resulted in a failure to serve requests.

Fixes #17503.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17788)

(cherry picked from commit aea68b0ddb7113b982ab503bf830d641e8425759)

diff --git a/apps/s_server.c b/apps/s_server.c
index 5ab58aebfa8506face4ce8476bd9c0e8b6ee9caa..acf577180afa7e6c31ef2632e54347c34576b663 100644 (file)
--- a/apps/s_server.c
+++ b/apps/s_server.c
@@ -2992,6 +2992,9 @@ static int www_body(int s, int stype, int prot, unsigned char *context)
     int total_bytes = 0;
 #endif
     int width;
+#ifndef OPENSSL_NO_KTLS
+    int use_sendfile_for_req = use_sendfile;
+#endif
     fd_set readfds;
     const char *opmode;
 #ifdef CHARSET_EBCDIC
@@ -3329,7 +3332,11 @@ static int www_body(int s, int stype, int prot, unsigned char *context)
             }
             /* send the file */
 #ifndef OPENSSL_NO_KTLS
-            if (use_sendfile) {
+            if (use_sendfile_for_req && !BIO_get_ktls_send(SSL_get_wbio(con))) {
+                BIO_printf(bio_err, "Warning: sendfile requested but KTLS is not available\n");
+                use_sendfile_for_req = 0;
+            }
+            if (use_sendfile_for_req) {
                 FILE *fp = NULL;
                 int fd;
                 struct stat st;