Catch hanging commands on server side

i.e. a buggy server that never sends a tagged response to a command

Otherwise, imaptest will hang until the connection is terminated (which
might be ~30 minutes)

src/commands.c

@@ -121,6 +121,13 @@ command_get_cmdline(struct imap_client *client, const char **_cmdline,
 	*_cmdline_len = str_len(str);
 }
 
+static void command_delay_timeout(struct imap_client *client)
+{
+	imap_client_input_error(client,
+				"Timeout while waiting for server response");
+	client_disconnect(&client->client);
+}
+
 struct command *command_send(struct imap_client *client, const char *cmdline,
 			     command_callback_t *callback)
 {
@@ -203,6 +210,10 @@ command_send_binary(struct imap_client *client, const char *cmdline,
 	o_stream_nsendv(client->client.output, iov, 3);
 	i_gettimeofday(&cmd->tv_start);
 
+	if (client->delay_timeout_ms > 0)
+		cmd->delay_to = timeout_add(client->delay_timeout_ms,
+					    command_delay_timeout, client);
+
 	array_append(&client->commands, &cmd, 1);
 	client->last_cmd = cmd;
 	return cmd;
@@ -231,6 +242,7 @@ void command_free(struct command *cmd)
 {
 	if (array_is_created(&cmd->seq_range))
 		array_free(&cmd->seq_range);
+	timeout_remove(&cmd->delay_to);
 	i_free(cmd->cmdline);
 	i_free(cmd);
 }

src/commands.h

@@ -26,6 +26,7 @@ struct command {
 
 	command_callback_t *callback;
 	struct timeval tv_start;
+	struct timeout *delay_to;
 
 	bool expect_bad:1;
 };

src/imap-client.h

@@ -74,6 +74,8 @@ struct imap_client {
 
 	int (*handle_untagged)(struct imap_client *, const struct imap_arg *);
 
+	unsigned int delay_timeout_ms;
+
 	bool seen_banner:1;
 	bool append_unfinished:1;
 	bool try_create_mailbox:1;

src/test-exec.c

@@ -23,6 +23,7 @@
 #include <ctype.h>
 
 #define IS_VAR_CHAR(c) (i_isalnum(c) || (c) == '_')
+#define TEST_EXEC_DELAY_TIMEOUT_SECS 30
 
 struct tests_execute_context {
 	const ARRAY_TYPE(test) *tests;
@@ -1320,6 +1321,8 @@ static int test_execute(const struct test *test,
 		ctx->clients[i]->client.v.send_more_commands =
 			test_send_lstate_commands;
 		ctx->clients[i]->test_exec_ctx = ctx;
+		ctx->clients[i]->delay_timeout_ms =
+			TEST_EXEC_DELAY_TIMEOUT_SECS * 1000;
 
 		key = i == 0 ? "user" : p_strdup_printf(pool, "user%u", i+1);
 		value = p_strdup(pool, ctx->clients[i]->client.user->username);