diff options
Diffstat (limited to 'login/utmpd/utmpd.c')
-rw-r--r-- | login/utmpd/utmpd.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/login/utmpd/utmpd.c b/login/utmpd/utmpd.c new file mode 100644 index 0000000..e112181 --- /dev/null +++ b/login/utmpd/utmpd.c @@ -0,0 +1,384 @@ +/* Copyright (C) 1997 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Mark Kettenis <kettenis@phys.uva.nl>, 1997. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <errno.h> +#include <fcntl.h> +#include <getopt.h> +#include <libintl.h> +#include <pwd.h> +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <string.h> +#include <sys/select.h> +#include <sys/socket.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/un.h> +#include <syslog.h> +#include <unistd.h> + +#include "utmpd.h" +#include "utmpd-private.h" + +/* Get libc version number. */ +#include "../../version.h" + +#define PACKAGE "libc" + +/* Long options. */ +static const struct option long_options[] = +{ + { "debug", no_argument, NULL, 'd' }, + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, 'V' }, + { NULL, 0, NULL, 0} +}; + +/* The UTMP database. */ +utmp_database *utmp_db; + +/* The socket for read only requests. */ +int ro_sock = -1; + +/* The socket for read/write requests. */ +int rw_sock = -1; + + +/* Prototypes for the local functions. */ +static void usage (int status) __attribute__ ((noreturn)); +static void drop_priviliges (void); +static int make_socket (const char *name); +static void handle_requests (void) __attribute__ ((noreturn)); +static void termination_handler (int signum); +static int check_pid (const char *file); +static int write_pid (const char *file); + + +int +main (int argc, char *argv[]) +{ + mode_t mask; + int debug; + int do_help; + int do_version; + int opt; + + /* Initialize local variables. */ + debug = 0; + do_help = 0; + do_version = 0; + + while ((opt = getopt_long (argc, argv, "dhV", long_options, NULL)) != -1) + switch (opt) + { + case '\0': /* Long option. */ + break; + case 'h': + do_help = 1; + break; + case 'd': + debug = 1; + break; + case 'V': + do_version = 1; + break; + default: + usage (EXIT_FAILURE); + } + + /* Version information is reequested. */ + if (do_version) + { + printf ("utmpd (GNU %s) %s\n", PACKAGE, VERSION); + printf (gettext ("\ +Copyright (C) %s Free Software Foundation, Inc.\n\ +This is free software; see the source for copying conditions. There is NO\n\ +warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\ +"), "1997"); + printf (gettext ("Written by %s.\n"), "Mark Kettenis"); + + exit (EXIT_SUCCESS); + } + + /* Help is requested. */ + if (do_help) + usage (EXIT_SUCCESS); + + signal (SIGINT, termination_handler); + signal (SIGTERM, termination_handler); + + /* Check if we are already running. */ + if (check_pid (_PATH_UTMPDPID)) + error (EXIT_FAILURE, 0, "already running"); + + /* Open UTMP database. */ + utmp_db = open_database (_PATH_UTMP "x", _PATH_UTMP); + if (utmp_db == NULL) + error (EXIT_FAILURE, errno, "%s", _PATH_UTMP); + + /* Create sockets, with the right permissions. */ + mask = umask (S_IXUSR | S_IXGRP | S_IXOTH); + ro_sock = make_socket (_PATH_UTMPD_RO); + umask (S_IXUSR | S_IRWXG | S_IRWXO); + rw_sock = make_socket (_PATH_UTMPD_RW); + umask (mask); + + /* Set the sockets up to accept connections. */ + if (listen (ro_sock, MAX_CONNECTIONS) < 0 + || listen (rw_sock, MAX_CONNECTIONS) < 0) + error (EXIT_FAILURE, errno, "cannot enable socket to accept connections"); + + /* Behave like a daemon. */ + if (!debug) + { + openlog ("utmpd", LOG_CONS | LOG_ODELAY, LOG_DAEMON); + + if (daemon (0, 0) < 0) + error (EXIT_FAILURE, errno, "cannot auto-background"); + forked = 1; + + if (write_pid (_PATH_UTMPDPID) < 0) + warning (errno, "%s", _PATH_UTMPDPID); + } + + /* Drop priviliges. */ + drop_priviliges (); + + /* Handle incoming requests. */ + handle_requests (); +} + + +/* Display usage information and exit. */ +static void +usage (int status) +{ + if (status != EXIT_SUCCESS) + fprintf (stderr, gettext ("Try `%s --help' for more information.\n"), + program_invocation_name); + else + { + printf (gettext ("\ +Usage: %s [OPTION]...\n\ + -d, --debug do not fork and display messages on the current tty\n\ + -h, --help display this help and exit\n\ + -V, --version output version information and exit\n"), + program_invocation_name); + fputs (gettext ("\ +Report bugs to <kettenis@phys.uva.nl>.\n"), + stdout); + } + + exit (status); +} + + +/* Drop priviliges. */ +static void +drop_priviliges (void) +{ + struct passwd *pw; + + pw = getpwnam ("daemon"); + if (pw) + { + seteuid (pw->pw_uid); + setegid (pw->pw_gid); + } +} + + +/* Make a socket in the file namespace using the filename NAME as the + socket's address. */ +static int +make_socket (const char *name) +{ + struct sockaddr_un addr; + size_t size; + int sock; + + /* Create the socket. */ + sock = socket (PF_UNIX, SOCK_STREAM, 0); + if (sock < 0) + error (EXIT_FAILURE, errno, "cannot create socket"); + + /* Bind a name to the socket. */ + addr.sun_family = AF_UNIX; + strcpy (addr.sun_path, name); + + /* The size of the address is the offset of the start + of the filename, plus its length, plus one for the + terminating null byte. */ + size = (offsetof (struct sockaddr_un, sun_path) + + strlen (addr.sun_path)); + + if (bind (sock, (struct sockaddr *) &addr, size) < 0) + error (EXIT_FAILURE, errno, "%s", name); + + return sock; +} + + +/* Hanlde incoming requests. */ +static +void handle_requests (void) +{ + client_connection *connection; + fd_set active_read_fd_set; + fd_set active_write_fd_set; + fd_set read_fd_set; + fd_set write_fd_set; + int fd; + + /* Initialize the set of active sockets. */ + FD_ZERO (&active_read_fd_set); + FD_ZERO (&active_write_fd_set); + FD_SET (rw_sock, &active_read_fd_set); + FD_SET (ro_sock, &active_read_fd_set); + + while (1) + { + /* Block until input arrives on one or more active sockets. */ + read_fd_set = active_read_fd_set; + write_fd_set = active_write_fd_set; + if (select (FD_SETSIZE, &read_fd_set, &write_fd_set, NULL, NULL) < 0) + error (EXIT_FAILURE, errno, "cannot get input on sockets"); + + /* Service all the sockets with input pending. */ + for (fd = 0; fd < FD_SETSIZE; fd++) + { + if (FD_ISSET (fd, &read_fd_set)) + { + if (fd == ro_sock || fd == rw_sock) + { + int access = ((fd == rw_sock) ? (R_OK | W_OK) : R_OK); + + connection = accept_connection (fd, access); + if (connection == NULL) + error (0, errno, "cannot accept connection"); + + FD_SET (connection->sock, &active_read_fd_set); + } + else + { + connection = find_connection (fd); + if (connection == NULL) + error (EXIT_FAILURE, 0, "cannot find connection"); + + if (read_data (connection) < 0) + { + close_connection (connection); + FD_CLR (fd, &active_read_fd_set); + FD_CLR (fd, &active_write_fd_set); + } + + if (connection->write_ptr > connection->write_base) + FD_SET (fd, &active_write_fd_set); + } + } + if (FD_ISSET (fd, &write_fd_set) && + fd != rw_sock && fd != ro_sock) + { + connection = find_connection (fd); + if (connection == NULL) + error (EXIT_FAILURE, 0, "cannot find connection"); + + if (write_data (connection) < 0) + { + close_connection (connection); + FD_CLR (fd, &active_read_fd_set); + FD_CLR (fd, &active_write_fd_set); + } + + if (connection->write_ptr == connection->write_base) + FD_CLR (fd, &active_write_fd_set); + } + } + } +} + + +/* Cleanup. */ +static void +termination_handler (int signum) +{ + /* Close sockets. */ + close (ro_sock); + close (rw_sock); + + /* Restore user id. */ + seteuid (getuid ()); + + /* Clean up the files created by `bind'. */ + unlink (_PATH_UTMPD_RO); + unlink (_PATH_UTMPD_RW); + + if (utmp_db) + close_database (utmp_db); + + /* Clean up pid file. */ + unlink (_PATH_UTMPDPID); + + exit (EXIT_SUCCESS); +} + + +/* Returns 1 if the process in pid file FILE is running, 0 if not. */ +static int +check_pid (const char *file) +{ + FILE *fp; + + fp = fopen (_PATH_UTMPDPID, "r"); + if (fp) + { + pid_t pid; + + fscanf (fp, "%d", &pid); + fclose (fp); + + if (kill (pid, 0) == 0) + return 1; + } + + return 0; +} + +/* Write the current process id to the file FILE. Returns 0 if + successful, -1 if not. */ +static int +write_pid (const char *file) +{ + FILE *fp; + + fp = fopen (_PATH_UTMPDPID, "w"); + if (fp == NULL) + return -1; + + fprintf (fp, "%d\n", getpid ()); + if (ferror (fp)) + return -1; + + fclose (fp); + + return 0; +} + |