Apply connect_timeout to TLS handshake

SSL_connect() blocks indefinitely when connecting with TLS to a non-TLS server.
Apply the connect_timeout as a socket timeout around the SSL_connect() call for
blocking connections.

Signed-off-by: Björn Svensson <bjorn.a.svensson@est.tech>

Author: bjosv

src/tls.c

@@ -376,7 +376,23 @@ static int valkeyTLSConnect(valkeyContext *c, SSL *ssl) {
 
     ERR_clear_error();
 
+    /* Apply connect_timeout to the TLS handshake. */
+    if ((c->flags & VALKEY_BLOCK) && c->connect_timeout != NULL) {
+        c->funcs->set_timeout(c, *c->connect_timeout);
+    }
+
     int rv = SSL_connect(rssl->ssl);
+
+    /* Restore the command_timeout. */
+    if ((c->flags & VALKEY_BLOCK) && c->connect_timeout != NULL) {
+        if (c->command_timeout != NULL) {
+            c->funcs->set_timeout(c, *c->command_timeout);
+        } else {
+            struct timeval tv_zero = {0, 0};
+            c->funcs->set_timeout(c, tv_zero);
+        }
+    }
+
     if (rv == 1) {
         c->funcs = &valkeyContextTLSFuncs;
         c->privctx = rssl;

tests/client_test.c

@@ -2676,6 +2676,36 @@ static void sharded_pubsub_test(struct config cfg) {
 }
 #endif /* VALKEY_TEST_ASYNC */
 
+#ifdef VALKEY_TEST_TLS
+/* Test that a TLS handshake to a non-TLS server times out using
+ * connect_timeout rather than hanging indefinitely. */
+static void test_tls_handshake_timeout(struct config config) {
+    test("TLS handshake to non-TLS port times out with connect_timeout: ");
+
+#ifndef _WIN32
+    /* Abort the test after 5 seconds. */
+    unsigned int old_alarm = alarm(5);
+#endif
+
+    struct timeval tv = {0, 100000}; /* 100ms */
+    valkeyOptions opt = {0};
+    VALKEY_OPTIONS_SET_TCP(&opt, config.tcp.host, config.tcp.port); /* TCP */
+    opt.connect_timeout = &tv;
+    /* No command timeout set. */
+
+    valkeyContext *c = valkeyConnectWithOptions(&opt);
+    assert(c != NULL && c->err == 0);
+
+    int rc = valkeyInitiateTLSWithContext(c, _tls_ctx);
+    test_cond(rc == VALKEY_ERR && c->err != 0);
+    valkeyFree(c);
+
+#ifndef _WIN32
+    alarm(old_alarm); /* Reset any alarm. */
+#endif
+}
+#endif /* VALKEY_TEST_TLS */
+
 int main(int argc, char **argv) {
     struct config cfg = {
         .tcp = {
@@ -2840,6 +2870,7 @@ int main(int argc, char **argv) {
         test_blocking_io_errors(cfg);
         test_invalid_timeout_errors(cfg);
         test_append_formatted_commands(cfg);
+        test_tls_handshake_timeout(cfg);
         if (throughput)
             test_throughput(cfg);