afs: Shutdown signals on exit.
[paraslash.git] / command.c
index 69564336c6f8228a072f699ad83dbbe19d154338..aea48146a38cefd7aeb22ea2994c9d53b5633c08 100644 (file)
--- 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 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;
 }