busybox/sysklogd/syslogd.c
2008-02-19 01:10:20 +00:00

665 lines
17 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Mini syslogd implementation for busybox
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
*
* Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
*
* "circular buffer" Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>
*
* Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include "libbb.h"
#define SYSLOG_NAMES
#define SYSLOG_NAMES_CONST
#include <syslog.h>
#include <paths.h>
#include <sys/un.h>
#include <sys/uio.h>
#if ENABLE_FEATURE_REMOTE_LOG
#include <netinet/in.h>
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#endif
#define DEBUG 0
/* MARK code is not very useful, is bloat, and broken:
* can deadlock if alarmed to make MARK while writing to IPC buffer
* (semaphores are down but do_mark routine tries to down them again) */
#undef SYSLOGD_MARK
enum {
MAX_READ = 256,
DNS_WAIT_SEC = 2 * 60,
};
/* Semaphore operation structures */
struct shbuf_ds {
int32_t size; /* size of data - 1 */
int32_t tail; /* end of message list */
char data[1]; /* data/messages */
};
/* Allows us to have smaller initializer. Ugly. */
#define GLOBALS \
const char *logFilePath; \
int logFD; \
/* interval between marks in seconds */ \
/*int markInterval;*/ \
/* level of messages to be logged */ \
int logLevel; \
USE_FEATURE_ROTATE_LOGFILE( \
/* max size of file before rotation */ \
unsigned logFileSize; \
/* number of rotated message files */ \
unsigned logFileRotate; \
unsigned curFileSize; \
smallint isRegular; \
) \
USE_FEATURE_REMOTE_LOG( \
/* udp socket for remote logging */ \
int remoteFD; \
len_and_sockaddr* remoteAddr; \
) \
USE_FEATURE_IPC_SYSLOG( \
int shmid; /* ipc shared memory id */ \
int s_semid; /* ipc semaphore id */ \
int shm_size; \
struct sembuf SMwup[1]; \
struct sembuf SMwdn[3]; \
)
struct init_globals {
GLOBALS
};
struct globals {
GLOBALS
#if ENABLE_FEATURE_REMOTE_LOG
unsigned last_dns_resolve;
char *remoteAddrStr;
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
struct shbuf_ds *shbuf;
#endif
time_t last_log_time;
/* localhost's name */
char localHostName[64];
/* We recv into recvbuf... */
char recvbuf[MAX_READ];
/* ...then copy to parsebuf, escaping control chars */
/* (can grow x2 max) */
char parsebuf[MAX_READ*2];
/* ...then sprintf into printbuf, adding timestamp (15 chars),
* host (64), fac.prio (20) to the message */
/* (growth by: 15 + 64 + 20 + delims = ~110) */
char printbuf[MAX_READ*2 + 128];
};
static const struct init_globals init_data = {
.logFilePath = "/var/log/messages",
.logFD = -1,
#ifdef SYSLOGD_MARK
.markInterval = 20 * 60,
#endif
.logLevel = 8,
#if ENABLE_FEATURE_ROTATE_LOGFILE
.logFileSize = 200 * 1024,
.logFileRotate = 1,
#endif
#if ENABLE_FEATURE_REMOTE_LOG
.remoteFD = -1,
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
.shmid = -1,
.s_semid = -1,
.shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024), // default shm size
.SMwup = { {1, -1, IPC_NOWAIT} },
.SMwdn = { {0, 0}, {1, 0}, {1, +1} },
#endif
};
#define G (*ptr_to_globals)
#define INIT_G() do { \
PTR_TO_GLOBALS = memcpy(xzalloc(sizeof(G)), &init_data, sizeof(init_data)); \
} while (0)
/* Options */
enum {
OPTBIT_mark = 0, // -m
OPTBIT_nofork, // -n
OPTBIT_outfile, // -O
OPTBIT_loglevel, // -l
OPTBIT_small, // -S
USE_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize ,) // -s
USE_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt ,) // -b
USE_FEATURE_REMOTE_LOG( OPTBIT_remote ,) // -R
USE_FEATURE_REMOTE_LOG( OPTBIT_locallog ,) // -L
USE_FEATURE_IPC_SYSLOG( OPTBIT_circularlog,) // -C
OPT_mark = 1 << OPTBIT_mark ,
OPT_nofork = 1 << OPTBIT_nofork ,
OPT_outfile = 1 << OPTBIT_outfile ,
OPT_loglevel = 1 << OPTBIT_loglevel,
OPT_small = 1 << OPTBIT_small ,
OPT_filesize = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize )) + 0,
OPT_rotatecnt = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt )) + 0,
OPT_remotelog = USE_FEATURE_REMOTE_LOG( (1 << OPTBIT_remote )) + 0,
OPT_locallog = USE_FEATURE_REMOTE_LOG( (1 << OPTBIT_locallog )) + 0,
OPT_circularlog = USE_FEATURE_IPC_SYSLOG( (1 << OPTBIT_circularlog)) + 0,
};
#define OPTION_STR "m:nO:l:S" \
USE_FEATURE_ROTATE_LOGFILE("s:" ) \
USE_FEATURE_ROTATE_LOGFILE("b:" ) \
USE_FEATURE_REMOTE_LOG( "R:" ) \
USE_FEATURE_REMOTE_LOG( "L" ) \
USE_FEATURE_IPC_SYSLOG( "C::")
#define OPTION_DECL *opt_m, *opt_l \
USE_FEATURE_ROTATE_LOGFILE(,*opt_s) \
USE_FEATURE_ROTATE_LOGFILE(,*opt_b) \
USE_FEATURE_IPC_SYSLOG( ,*opt_C = NULL)
#define OPTION_PARAM &opt_m, &G.logFilePath, &opt_l \
USE_FEATURE_ROTATE_LOGFILE(,&opt_s) \
USE_FEATURE_ROTATE_LOGFILE(,&opt_b) \
USE_FEATURE_REMOTE_LOG( ,&G.remoteAddrStr) \
USE_FEATURE_IPC_SYSLOG( ,&opt_C)
/* circular buffer variables/structures */
#if ENABLE_FEATURE_IPC_SYSLOG
#if CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE < 4
#error Sorry, you must set the syslogd buffer size to at least 4KB.
#error Please check CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
#endif
/* our shared key */
#define KEY_ID ((long)0x414e4547) /* "GENA" */
static void ipcsyslog_cleanup(void)
{
if (G.shmid != -1) {
shmdt(G.shbuf);
}
if (G.shmid != -1) {
shmctl(G.shmid, IPC_RMID, NULL);
}
if (G.s_semid != -1) {
semctl(G.s_semid, 0, IPC_RMID, 0);
}
}
static void ipcsyslog_init(void)
{
if (DEBUG)
printf("shmget(%lx, %d,...)\n", KEY_ID, G.shm_size);
G.shmid = shmget(KEY_ID, G.shm_size, IPC_CREAT | 0644);
if (G.shmid == -1) {
bb_perror_msg_and_die("shmget");
}
G.shbuf = shmat(G.shmid, NULL, 0);
if (G.shbuf == (void*) -1L) { /* shmat has bizarre error return */
bb_perror_msg_and_die("shmat");
}
memset(G.shbuf, 0, G.shm_size);
G.shbuf->size = G.shm_size - offsetof(struct shbuf_ds, data) - 1;
/*G.shbuf->tail = 0;*/
// we'll trust the OS to set initial semval to 0 (let's hope)
G.s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023);
if (G.s_semid == -1) {
if (errno == EEXIST) {
G.s_semid = semget(KEY_ID, 2, 0);
if (G.s_semid != -1)
return;
}
bb_perror_msg_and_die("semget");
}
}
/* Write message to shared mem buffer */
static void log_to_shmem(const char *msg, int len)
{
int old_tail, new_tail;
if (semop(G.s_semid, G.SMwdn, 3) == -1) {
bb_perror_msg_and_die("SMwdn");
}
/* Circular Buffer Algorithm:
* --------------------------
* tail == position where to store next syslog message.
* tail's max value is (shbuf->size - 1)
* Last byte of buffer is never used and remains NUL.
*/
len++; /* length with NUL included */
again:
old_tail = G.shbuf->tail;
new_tail = old_tail + len;
if (new_tail < G.shbuf->size) {
/* store message, set new tail */
memcpy(G.shbuf->data + old_tail, msg, len);
G.shbuf->tail = new_tail;
} else {
/* k == available buffer space ahead of old tail */
int k = G.shbuf->size - old_tail;
/* copy what fits to the end of buffer, and repeat */
memcpy(G.shbuf->data + old_tail, msg, k);
msg += k;
len -= k;
G.shbuf->tail = 0;
goto again;
}
if (semop(G.s_semid, G.SMwup, 1) == -1) {
bb_perror_msg_and_die("SMwup");
}
if (DEBUG)
printf("tail:%d\n", G.shbuf->tail);
}
#else
void ipcsyslog_cleanup(void);
void ipcsyslog_init(void);
void log_to_shmem(const char *msg);
#endif /* FEATURE_IPC_SYSLOG */
/* Print a message to the log file. */
static void log_locally(time_t now, char *msg)
{
struct flock fl;
int len = strlen(msg);
#if ENABLE_FEATURE_IPC_SYSLOG
if ((option_mask32 & OPT_circularlog) && G.shbuf) {
log_to_shmem(msg, len);
return;
}
#endif
if (G.logFD >= 0) {
if (!now)
now = time(NULL);
if (G.last_log_time != now) {
G.last_log_time = now; /* reopen log file every second */
close(G.logFD);
goto reopen;
}
} else {
reopen:
G.logFD = device_open(G.logFilePath, O_WRONLY | O_CREAT
| O_NOCTTY | O_APPEND | O_NONBLOCK);
if (G.logFD < 0) {
/* cannot open logfile? - print to /dev/console then */
int fd = device_open(DEV_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
if (fd < 0)
fd = 2; /* then stderr, dammit */
full_write(fd, msg, len);
if (fd != 2)
close(fd);
return;
}
#if ENABLE_FEATURE_ROTATE_LOGFILE
{
struct stat statf;
G.isRegular = (fstat(G.logFD, &statf) == 0 && S_ISREG(statf.st_mode));
/* bug (mostly harmless): can wrap around if file > 4gb */
G.curFileSize = statf.st_size;
}
#endif
}
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = 1;
fl.l_type = F_WRLCK;
fcntl(G.logFD, F_SETLKW, &fl);
#if ENABLE_FEATURE_ROTATE_LOGFILE
if (G.logFileSize && G.isRegular && G.curFileSize > G.logFileSize) {
if (G.logFileRotate) { /* always 0..99 */
int i = strlen(G.logFilePath) + 3 + 1;
char oldFile[i];
char newFile[i];
i = G.logFileRotate - 1;
/* rename: f.8 -> f.9; f.7 -> f.8; ... */
while (1) {
sprintf(newFile, "%s.%d", G.logFilePath, i);
if (i == 0) break;
sprintf(oldFile, "%s.%d", G.logFilePath, --i);
xrename(oldFile, newFile);
}
/* newFile == "f.0" now */
xrename(G.logFilePath, newFile);
fl.l_type = F_UNLCK;
fcntl(G.logFD, F_SETLKW, &fl);
close(G.logFD);
goto reopen;
}
ftruncate(G.logFD, 0);
}
G.curFileSize +=
#endif
full_write(G.logFD, msg, len);
fl.l_type = F_UNLCK;
fcntl(G.logFD, F_SETLKW, &fl);
}
static void parse_fac_prio_20(int pri, char *res20)
{
const CODE *c_pri, *c_fac;
if (pri != 0) {
c_fac = facilitynames;
while (c_fac->c_name) {
if (c_fac->c_val != (LOG_FAC(pri) << 3)) {
c_fac++;
continue;
}
/* facility is found, look for prio */
c_pri = prioritynames;
while (c_pri->c_name) {
if (c_pri->c_val != LOG_PRI(pri)) {
c_pri++;
continue;
}
snprintf(res20, 20, "%s.%s",
c_fac->c_name, c_pri->c_name);
return;
}
/* prio not found, bail out */
break;
}
snprintf(res20, 20, "<%d>", pri);
}
}
/* len parameter is used only for "is there a timestamp?" check.
* NB: some callers cheat and supply len==0 when they know
* that there is no timestamp, short-circuiting the test. */
static void timestamp_and_log(int pri, char *msg, int len)
{
char *timestamp;
time_t now;
if (len < 16 || msg[3] != ' ' || msg[6] != ' '
|| msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
) {
time(&now);
timestamp = ctime(&now) + 4; /* skip day of week */
} else {
now = 0;
timestamp = msg;
msg += 16;
}
timestamp[15] = '\0';
if (option_mask32 & OPT_small)
sprintf(G.printbuf, "%s %s\n", timestamp, msg);
else {
char res[20];
parse_fac_prio_20(pri, res);
sprintf(G.printbuf, "%s %s %s %s\n", timestamp, G.localHostName, res, msg);
}
/* Log message locally (to file or shared mem) */
log_locally(now, G.printbuf);
}
static void timestamp_and_log_internal(const char *msg)
{
if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_locallog))
return;
timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)msg, 0);
}
/* tmpbuf[len] is a NUL byte (set by caller), but there can be other,
* embedded NULs. Split messages on each of these NULs, parse prio,
* escape control chars and log each locally. */
static void split_escape_and_log(char *tmpbuf, int len)
{
char *p = tmpbuf;
tmpbuf += len;
while (p < tmpbuf) {
char c;
char *q = G.parsebuf;
int pri = (LOG_USER | LOG_NOTICE);
if (*p == '<') {
/* Parse the magic priority number */
pri = bb_strtou(p + 1, &p, 10);
if (*p == '>')
p++;
if (pri & ~(LOG_FACMASK | LOG_PRIMASK))
pri = (LOG_USER | LOG_NOTICE);
}
while ((c = *p++)) {
if (c == '\n')
c = ' ';
if (!(c & ~0x1f) && c != '\t') {
*q++ = '^';
c += '@'; /* ^@, ^A, ^B... */
}
*q++ = c;
}
*q = '\0';
/* Now log it */
if (LOG_PRI(pri) < G.logLevel)
timestamp_and_log(pri, G.parsebuf, q - G.parsebuf);
}
}
static void quit_signal(int sig)
{
timestamp_and_log_internal("syslogd exiting");
puts("syslogd exiting");
if (ENABLE_FEATURE_IPC_SYSLOG)
ipcsyslog_cleanup();
exit(1);
}
#ifdef SYSLOGD_MARK
static void do_mark(int sig)
{
if (G.markInterval) {
timestamp_and_log_internal("-- MARK --");
alarm(G.markInterval);
}
}
#endif
/* Don't inline: prevent struct sockaddr_un to take up space on stack
* permanently */
static NOINLINE int create_socket(void)
{
struct sockaddr_un sunx;
int sock_fd;
char *dev_log_name;
memset(&sunx, 0, sizeof(sunx));
sunx.sun_family = AF_UNIX;
/* Unlink old /dev/log or object it points to. */
/* (if it exists, bind will fail) */
strcpy(sunx.sun_path, "/dev/log");
dev_log_name = xmalloc_follow_symlinks("/dev/log");
if (dev_log_name) {
safe_strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
free(dev_log_name);
}
unlink(sunx.sun_path);
sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
xbind(sock_fd, (struct sockaddr *) &sunx, sizeof(sunx));
chmod("/dev/log", 0666);
return sock_fd;
}
#if ENABLE_FEATURE_REMOTE_LOG
static int try_to_resolve_remote(void)
{
if (!G.remoteAddr) {
unsigned now = monotonic_sec();
/* Don't resolve name too often - DNS timeouts can be big */
if ((now - G.last_dns_resolve) < DNS_WAIT_SEC)
return -1;
G.last_dns_resolve = now;
G.remoteAddr = host2sockaddr(G.remoteAddrStr, 514);
if (!G.remoteAddr)
return -1;
}
return socket(G.remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
}
#endif
static void do_syslogd(void) ATTRIBUTE_NORETURN;
static void do_syslogd(void)
{
int sock_fd;
/* Set up signal handlers */
bb_signals(0
+ (1 << SIGINT)
+ (1 << SIGTERM)
+ (1 << SIGQUIT)
, quit_signal);
signal(SIGHUP, SIG_IGN);
/* signal(SIGCHLD, SIG_IGN); - why? */
#ifdef SYSLOGD_MARK
signal(SIGALRM, do_mark);
alarm(G.markInterval);
#endif
sock_fd = create_socket();
if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
ipcsyslog_init();
}
timestamp_and_log_internal("syslogd started: BusyBox v" BB_VER);
for (;;) {
size_t sz;
read_again:
sz = safe_read(sock_fd, G.recvbuf, MAX_READ - 1);
if (sz < 0)
bb_perror_msg_and_die("read from /dev/log");
/* Drop trailing '\n' and NULs (typically there is one NUL) */
while (1) {
if (sz == 0)
goto read_again;
/* man 3 syslog says: "A trailing newline is added when needed".
* However, neither glibc nor uclibc do this:
* syslog(prio, "test") sends "test\0" to /dev/log,
* syslog(prio, "test\n") sends "test\n\0".
* IOW: newline is passed verbatim!
* I take it to mean that it's syslogd's job
* to make those look identical in the log files. */
if (G.recvbuf[sz-1] != '\0' && G.recvbuf[sz-1] != '\n')
break;
sz--;
}
/* TODO: maybe suppress duplicates? */
#if ENABLE_FEATURE_REMOTE_LOG
/* We are not modifying log messages in any way before send */
/* Remote site cannot trust _us_ anyway and need to do validation again */
if (G.remoteAddrStr) {
if (-1 == G.remoteFD) {
G.remoteFD = try_to_resolve_remote();
if (-1 == G.remoteFD)
goto no_luck;
}
/* Stock syslogd sends it '\n'-terminated
* over network, mimic that */
G.recvbuf[sz] = '\n';
/* send message to remote logger, ignore possible error */
/* TODO: on some errors, close and set G.remoteFD to -1
* so that DNS resolution and connect is retried? */
sendto(G.remoteFD, G.recvbuf, sz+1, MSG_DONTWAIT,
&G.remoteAddr->u.sa, G.remoteAddr->len);
no_luck: ;
}
#endif
if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
G.recvbuf[sz] = '\0'; /* ensure it *is* NUL terminated */
split_escape_and_log(G.recvbuf, sz);
}
} /* for (;;) */
}
int syslogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int syslogd_main(int argc, char **argv)
{
char OPTION_DECL;
char *p;
INIT_G();
#if ENABLE_FEATURE_REMOTE_LOG
G.last_dns_resolve = monotonic_sec() - DNS_WAIT_SEC - 1;
#endif
/* do normal option parsing */
opt_complementary = "=0"; /* no non-option params */
getopt32(argv, OPTION_STR, OPTION_PARAM);
#ifdef SYSLOGD_MARK
if (option_mask32 & OPT_mark) // -m
G.markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
#endif
//if (option_mask32 & OPT_nofork) // -n
//if (option_mask32 & OPT_outfile) // -O
if (option_mask32 & OPT_loglevel) // -l
G.logLevel = xatou_range(opt_l, 1, 8);
//if (option_mask32 & OPT_small) // -S
#if ENABLE_FEATURE_ROTATE_LOGFILE
if (option_mask32 & OPT_filesize) // -s
G.logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
if (option_mask32 & OPT_rotatecnt) // -b
G.logFileRotate = xatou_range(opt_b, 0, 99);
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
if (opt_C) // -Cn
G.shm_size = xatoul_range(opt_C, 4, INT_MAX/1024) * 1024;
#endif
/* If they have not specified remote logging, then log locally */
if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_remotelog))
option_mask32 |= OPT_locallog;
/* Store away localhost's name before the fork */
gethostname(G.localHostName, sizeof(G.localHostName));
/* "It is unspecified whether the truncated hostname
* will be null-terminated". Idiots! */
G.localHostName[sizeof(G.localHostName) - 1] = '\0';
*strchrnul(G.localHostName, '.') = '\0';
if (!(option_mask32 & OPT_nofork)) {
bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
}
umask(0);
write_pidfile("/var/run/syslogd.pid");
do_syslogd();
/* return EXIT_SUCCESS; */
}