X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=command.c;h=aea48146a38cefd7aeb22ea2994c9d53b5633c08;hp=69564336c6f8228a072f699ad83dbbe19d154338;hb=07daa886fda65b868966c19e812c42433ffbfd5b;hpb=c52dfd608f15c8779df38fd46602e562b287171a

diff --git a/command.c b/command.c
index 69564336..aea48146 100644
--- a/command.c
+++ b/command.c
@@ -1,8 +1,4 @@
-/*
- * Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
 
 /** \file command.c Client authentication and server commands. */
 
@@ -52,11 +48,15 @@ static const char * const server_command_perms_txt[] = {LSG_SERVER_CMD_AUX_INFOS
 
 extern int mmd_mutex;
 extern struct misc_meta_data *mmd;
-extern struct sender senders[];
 int send_afs_status(struct command_context *cc, int parser_friendly);
+static bool subcmd_should_die;
 
-static void dummy(__a_unused int s)
+static void command_handler_sighandler(int s)
 {
+	if (s != SIGTERM)
+		return;
+	PARA_EMERG_LOG("terminating on signal %d\n", SIGTERM);
+	subcmd_should_die = true;
 }
 
 /*
@@ -239,10 +239,10 @@ static int check_sender_args(struct command_context *cc,
 		return ret;
 	}
 	arg = lls_input(0, lpr);
-	for (i = 0; senders[i].name; i++)
-		if (!strcmp(senders[i].name, arg))
+	FOR_EACH_SENDER(i)
+		if (strcmp(senders[i]->name, arg) == 0)
 			break;
-	if (!senders[i].name)
+	if (!senders[i])
 		return -E_COMMAND_SYNTAX;
 	scd->sender_num = i;
 	arg = lls_input(1, lpr);
@@ -252,7 +252,7 @@ static int check_sender_args(struct command_context *cc,
 	if (i == NUM_SENDER_CMDS)
 		return -E_COMMAND_SYNTAX;
 	scd->cmd_num = i;
-	if (!senders[scd->sender_num].client_cmds[scd->cmd_num])
+	if (!senders[scd->sender_num]->client_cmds[scd->cmd_num])
 		return -E_SENDER_CMD;
 	switch (scd->cmd_num) {
 	case SENDER_on:
@@ -334,10 +334,10 @@ static int com_sender(struct command_context *cc, struct lls_parse_result *lpr)
 	struct sender_command_data scd;
 
 	if (lls_num_inputs(lpr) == 0) {
-		for (i = 0; senders[i].name; i++) {
+		FOR_EACH_SENDER(i) {
 			char *tmp;
 			ret = xasprintf(&tmp, "%s%s\n", msg? msg : "",
-				senders[i].name);
+				senders[i]->name);
 			free(msg);
 			msg = tmp;
 		}
@@ -348,17 +348,17 @@ static int com_sender(struct command_context *cc, struct lls_parse_result *lpr)
 		if (scd.sender_num < 0)
 			return ret;
 		if (strcmp(lls_input(1, lpr), "status") == 0)
-			msg = senders[scd.sender_num].status();
+			msg = senders[scd.sender_num]->status();
 		else
-			msg = senders[scd.sender_num].help();
+			msg = senders[scd.sender_num]->help();
 		return send_sb(&cc->scc, msg, strlen(msg), SBD_OUTPUT, false);
 	}
 
 	switch (scd.cmd_num) {
 	case SENDER_add:
 	case SENDER_delete:
-		assert(senders[scd.sender_num].resolve_target);
-		ret = senders[scd.sender_num].resolve_target(lls_input(2, lpr),
+		assert(senders[scd.sender_num]->resolve_target);
+		ret = senders[scd.sender_num]->resolve_target(lls_input(2, lpr),
 			&scd);
 		if (ret < 0)
 			return ret;
@@ -398,7 +398,7 @@ static int com_si(struct command_context *cc,
 		"supported audio formats: %s\n",
 		ut, mmd->num_played,
 		(int)getppid(),
-		(int)mmd->afs_pid,
+		(int)afs_pid,
 		mmd->active_connections,
 		mmd->num_commands,
 		mmd->num_connects,
@@ -497,9 +497,21 @@ static int com_stat(struct command_context *cc, struct lls_parse_result *lpr)
 	bool parser_friendly = SERVER_CMD_OPT_GIVEN(STAT, PARSER_FRIENDLY,
 		lpr) > 0;
 	uint32_t num = SERVER_CMD_UINT32_VAL(STAT, NUM, lpr);
+	const struct timespec ts = {.tv_sec = 50, .tv_nsec = 0};
 
-	para_sigaction(SIGUSR1, dummy);
+	para_sigaction(SIGINT, SIG_IGN);
+	para_sigaction(SIGUSR1, command_handler_sighandler);
+	para_sigaction(SIGTERM, command_handler_sighandler);
+	/*
+	 * Simply checking subcmd_should_die is racy because a signal may
+	 * arrive after the check but before the subsequent call to sleep(3).
+	 * If this happens, sleep(3) would not be interrupted by the signal.
+	 * To avoid this we block SIGTERM here and allow it to arrive only
+	 * while we sleep.
+	 */
+	para_block_signal(SIGTERM);
 	for (;;) {
+		sigset_t set;
 		/*
 		 * Copy the mmd structure to minimize the time we hold the mmd
 		 * lock.
@@ -522,7 +534,15 @@ static int com_stat(struct command_context *cc, struct lls_parse_result *lpr)
 		ret = 1;
 		if (num > 0 && !--num)
 			goto out;
-		sleep(50);
+		sigemptyset(&set); /* empty set means: unblock all signals */
+		/*
+		 * pselect(2) allows to atomically unblock signals, then go to
+		 * sleep. Calling sigprocmask(2) followed by sleep(3) would
+		 * open a race window similar to the one described above.
+		 */
+		pselect(1, NULL, NULL, NULL, &ts, &set);
+		if (subcmd_should_die)
+			goto out;
 		ret = -E_SERVER_CRASH;
 		if (getppid() == 1)
 			goto out;
@@ -744,12 +764,11 @@ out:
 }
 EXPORT_SERVER_CMD_HANDLER(jmp);
 
-static int com_tasks(struct command_context *cc,
+/* deprecated, does nothing */
+static int com_tasks(__a_unused struct command_context *cc,
 		__a_unused struct lls_parse_result *lpr)
 {
-	char *tl = server_get_tasks();
-	assert(tl);
-	return send_sb(&cc->scc, tl, strlen(tl), SBD_OUTPUT, false);
+	return 1;
 }
 EXPORT_SERVER_CMD_HANDLER(tasks);
 
@@ -765,7 +784,7 @@ struct connection_features {
 	int dummy; /* none at the moment */
 };
 
-static int parse_auth_request(char *buf, int len, struct user **u,
+static int parse_auth_request(char *buf, int len, const struct user **u,
 		struct connection_features *cf)
 {
 	int ret;
@@ -799,7 +818,7 @@ static int parse_auth_request(char *buf, int len, struct user **u,
 		}
 	}
 	PARA_DEBUG_LOG("received auth request for user %s\n", username);
-	*u = lookup_user(username);
+	*u = user_list_lookup(username);
 	ret = 1;
 out:
 	free_argv(features);
@@ -808,8 +827,7 @@ out:
 
 #define HANDSHAKE_BUFSIZE 4096
 
-static int run_command(struct command_context *cc, struct iovec *iov,
-		const char *peername)
+static int run_command(struct command_context *cc, struct iovec *iov)
 {
 	int ret, i, argc;
 	char *p, *end, **argv;
@@ -842,8 +860,8 @@ static int run_command(struct command_context *cc, struct iovec *iov,
 		p += strlen(p) + 1;
 	}
 	argv[argc] = NULL;
-	PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", lls_command_name(lcmd),
-		cc->u->name, peername);
+	PARA_NOTICE_LOG("calling com_%s() for user %s\n",
+		lls_command_name(lcmd), cc->u->name);
 	ret = lls(lls_parse(argc, argv, lcmd, &lpr, &errctx));
 	if (ret >= 0) {
 		const struct server_cmd_user_data *ud = lls_user_data(lcmd);
@@ -864,7 +882,6 @@ static int run_command(struct command_context *cc, struct iovec *iov,
  * Perform user authentication and execute a command.
  *
  * \param fd The file descriptor to send output to.
- * \param peername Identifies the connecting peer.
  *
  * Whenever para_server accepts an incoming tcp connection on the port it
  * listens on, it forks and the resulting child calls this function.
@@ -879,13 +896,13 @@ static int run_command(struct command_context *cc, struct iovec *iov,
  * permissions to execute that command, the function calls the corresponding
  * command handler which does argument checking and further processing.
  *
- * In order to cope with a DOS attacks, a timeout is set up which terminates
+ * In order to cope with DOS attacks, a timeout is set up which terminates
  * the function if the connection was not authenticated when the timeout
  * expires.
  *
  * \sa alarm(2), \ref crypt.c, \ref crypt.h.
  */
-__noreturn void handle_connect(int fd, const char *peername)
+int handle_connect(int fd)
 {
 	int ret;
 	unsigned char rand_buf[CHALLENGE_SIZE + 2 * SESSION_KEY_LEN];
@@ -971,7 +988,7 @@ __noreturn void handle_connect(int fd, const char *peername)
 	ret = recv_sb(&cc->scc, SBD_COMMAND, MAX_COMMAND_LEN, &iov);
 	if (ret < 0)
 		goto net_err;
-	ret = run_command(cc, &iov, peername);
+	ret = run_command(cc, &iov);
 	free(iov.iov_base);
 	if (ret < 0)
 		goto err_out;
@@ -995,5 +1012,5 @@ out:
 	}
 	sc_free(cc->scc.recv);
 	sc_free(cc->scc.send);
-	exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
+	return ret;
 }