Do not reset SNI data in SSL_do_handshake()

PR #3783 introduce coded to reset the server side SNI state in
SSL_do_handshake() to ensure any erroneous config time SNI changes are
cleared. Unfortunately SSL_do_handshake() can be called mid-handshake
multiple times so this is the wrong place to do this and can mean that
any SNI data is cleared later on in the handshake too.

Therefore move the code to a more appropriate place.

Fixes #7014

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/7149)

ssl/ssl_lib.c

@@ -3559,12 +3559,6 @@ int SSL_do_handshake(SSL *s)
 
     s->method->ssl_renegotiate_check(s, 0);
 
-    if (SSL_is_server(s)) {
-        /* clear SNI settings at server-side */
-        OPENSSL_free(s->ext.hostname);
-        s->ext.hostname = NULL;
-    }
-
     if (SSL_in_init(s) || SSL_in_before(s)) {
         if ((s->mode & SSL_MODE_ASYNC) && ASYNC_get_current_job() == NULL) {
             struct ssl_async_args args;

ssl/statem/extensions.c

@@ -904,9 +904,13 @@ static int final_renegotiate(SSL *s, unsigned int context, int sent)
 
 static int init_server_name(SSL *s, unsigned int context)
 {
-    if (s->server)
+    if (s->server) {
         s->servername_done = 0;
 
+        OPENSSL_free(s->ext.hostname);
+        s->ext.hostname = NULL;
+    }
+
     return 1;
 }
 

test/build.info

@@ -364,7 +364,7 @@ INCLUDE_MAIN___test_libtestutil_OLB = /INCLUDE=MAIN
   INCLUDE[ciphername_test]=../include
   DEPEND[ciphername_test]=../libcrypto ../libssl libtestutil.a
 
-  SOURCE[servername_test]=servername_test.c
+  SOURCE[servername_test]=servername_test.c ssltestlib.c
   INCLUDE[servername_test]=../include
   DEPEND[servername_test]=../libcrypto ../libssl libtestutil.a
 

test/recipes/70-test_servername.t

@@ -11,7 +11,7 @@ use strict;
 use warnings;
 
 use OpenSSL::Test::Simple;
-use OpenSSL::Test;
+use OpenSSL::Test qw/:DEFAULT srctop_file/;
 use OpenSSL::Test::Utils qw(alldisabled available_protocols);
 
 setup("test_servername");
@@ -19,4 +19,8 @@ setup("test_servername");
 plan skip_all => "No TLS/SSL protocols are supported by this OpenSSL build"
     if alldisabled(grep { $_ ne "ssl3" } available_protocols("tls"));
 
-simple_test("test_servername", "servername_test");
+plan tests => 1;
+
+ok(run(test(["servername_test", srctop_file("apps", "server.pem"),
+             srctop_file("apps", "server.pem")])),
+             "running servername_test");

test/servername_test.c

@@ -22,11 +22,15 @@
 
 #include "testutil.h"
 #include "internal/nelem.h"
+#include "ssltestlib.h"
 
 #define CLIENT_VERSION_LEN      2
 
 static const char *host = "dummy-host";
 
+static char *cert = NULL;
+static char *privkey = NULL;
+
 static int get_sni_from_client_hello(BIO *bio, char **sni)
 {
     long len;
@@ -176,45 +180,38 @@ end:
 
 static int server_setup_sni(void)
 {
-    SSL_CTX *ctx;
-    SSL *con = NULL;
-    BIO *rbio;
-    BIO *wbio;
-    int ret = 0;
+    SSL_CTX *cctx = NULL, *sctx = NULL;
+    SSL *clientssl = NULL, *serverssl = NULL;
+    int testresult = 0;
 
-    /* use TLS_server_method to choose 'server-side' */
-    ctx = SSL_CTX_new(TLS_server_method());
-    if (!TEST_ptr(ctx))
+    if (!TEST_true(create_ssl_ctx_pair(TLS_server_method(),
+                                       TLS_client_method(),
+                                       TLS1_VERSION, TLS_MAX_VERSION,
+                                       &sctx, &cctx, cert, privkey))
+            || !TEST_true(create_ssl_objects(sctx, cctx, &serverssl, &clientssl,
+                                             NULL, NULL)))
         goto end;
 
-    con = SSL_new(ctx);
-    if (!TEST_ptr(con))
-        goto end;
-
-    rbio = BIO_new(BIO_s_mem());
-    wbio = BIO_new(BIO_s_mem());
-    if (!TEST_ptr(rbio)|| !TEST_ptr(wbio)) {
-        BIO_free(rbio);
-        BIO_free(wbio);
-        goto end;
-    }
-
-    SSL_set_bio(con, rbio, wbio);
-
     /* set SNI at server side */
-    SSL_set_tlsext_host_name(con, host);
+    SSL_set_tlsext_host_name(serverssl, host);
 
-    if (!TEST_int_le(SSL_accept(con), 0))
-        /* This shouldn't succeed because we have nothing to listen on */
+    if (!TEST_true(create_ssl_connection(serverssl, clientssl, SSL_ERROR_NONE)))
         goto end;
-    if (!TEST_ptr_null(SSL_get_servername(con, TLSEXT_NAMETYPE_host_name)))
-        /* SNI should be cleared by SSL_accpet */
+
+    if (!TEST_ptr_null(SSL_get_servername(serverssl,
+                                          TLSEXT_NAMETYPE_host_name))) {
+        /* SNI should have been cleared during handshake */
         goto end;
-    ret = 1;
+    }
+    
+    testresult = 1;
 end:
-    SSL_free(con);
-    SSL_CTX_free(ctx);
-    return ret;
+    SSL_free(serverssl);
+    SSL_free(clientssl);
+    SSL_CTX_free(sctx);
+    SSL_CTX_free(cctx);
+
+    return testresult;
 }
 
 typedef int (*sni_test_fn)(void);
@@ -236,6 +233,10 @@ static int test_servername(int test)
 
 int setup_tests(void)
 {
+    if (!TEST_ptr(cert = test_get_argument(0))
+            || !TEST_ptr(privkey = test_get_argument(1)))
+        return 0;
+
     ADD_ALL_TESTS(test_servername, OSSL_NELEM(sni_test_fns));
     return 1;
 }