sysklogd/syslogd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini syslogd implementation for busybox
   4  *
   5  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   6  *
   7  * Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
   8  *
   9  * "circular buffer" Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>
  10  *
  11  * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
  12  *
  13  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  14  */
  15
  16 /*
  17  * Done in syslogd_and_logger.c:
  18 #include "libbb.h"
  19 #define SYSLOG_NAMES
  20 #define SYSLOG_NAMES_CONST
  21 #include <syslog.h>
  22 */
  23
  24 #include <sys/un.h>
  25 #include <sys/uio.h>
  26
  27 #if ENABLE_FEATURE_REMOTE_LOG
  28 #include <netinet/in.h>
  29 #endif
  30
  31 #if ENABLE_FEATURE_IPC_SYSLOG
  32 #include <sys/ipc.h>
  33 #include <sys/sem.h>
  34 #include <sys/shm.h>
  35 #endif
  36
  37
  38 #define DEBUG 0
  39
  40 /* MARK code is not very useful, is bloat, and broken:
  41  * can deadlock if alarmed to make MARK while writing to IPC buffer
  42  * (semaphores are down but do_mark routine tries to down them again) */
  43 #undef SYSLOGD_MARK
  44
  45 /* Write locking does not seem to be useful either */
  46 #undef SYSLOGD_WRLOCK
  47
  48 enum {
  49         MAX_READ = CONFIG_FEATURE_SYSLOGD_READ_BUFFER_SIZE,
  50         DNS_WAIT_SEC = 2 * 60,
  51 };
  52
  53 /* Semaphore operation structures */
  54 struct shbuf_ds {
  55         int32_t size;   /* size of data - 1 */
  56         int32_t tail;   /* end of message list */
  57         char data[1];   /* data/messages */
  58 };
  59
  60 #if ENABLE_FEATURE_REMOTE_LOG
  61 typedef struct {
  62         int remoteFD;
  63         unsigned last_dns_resolve;
  64         len_and_sockaddr *remoteAddr;
  65         const char *remoteHostname;
  66 } remoteHost_t;
  67 #endif
  68
  69 typedef struct logFile_t {
  70         const char *path;
  71         int fd;
  72 #if ENABLE_FEATURE_ROTATE_LOGFILE
  73         unsigned size;
  74         uint8_t isRegular;
  75 #endif
  76 } logFile_t;
  77
  78 #if ENABLE_FEATURE_SYSLOGD_CFG
  79 typedef struct logRule_t {
  80         uint8_t enabled_facility_priomap[LOG_NFACILITIES];
  81         struct logFile_t *file;
  82         struct logRule_t *next;
  83 } logRule_t;
  84 #endif
  85
  86 /* Allows us to have smaller initializer. Ugly. */
  87 #define GLOBALS \
  88         logFile_t logFile;                      \
  89         /* interval between marks in seconds */ \
  90         /*int markInterval;*/                   \
  91         /* level of messages to be logged */    \
  92         int logLevel;                           \
  93 IF_FEATURE_ROTATE_LOGFILE( \
  94         /* max size of file before rotation */  \
  95         unsigned logFileSize;                   \
  96         /* number of rotated message files */   \
  97         unsigned logFileRotate;                 \
  98 ) \
  99 IF_FEATURE_IPC_SYSLOG( \
 100         int shmid; /* ipc shared memory id */   \
 101         int s_semid; /* ipc semaphore id */     \
 102         int shm_size;                           \
 103         struct sembuf SMwup[1];                 \
 104         struct sembuf SMwdn[3];                 \
 105 ) \
 106 IF_FEATURE_SYSLOGD_CFG( \
 107         logRule_t *log_rules; \
 108 )
 109
 110 struct init_globals {
 111         GLOBALS
 112 };
 113
 114 struct globals {
 115         GLOBALS
 116
 117 #if ENABLE_FEATURE_REMOTE_LOG
 118         llist_t *remoteHosts;
 119 #endif
 120 #if ENABLE_FEATURE_IPC_SYSLOG
 121         struct shbuf_ds *shbuf;
 122 #endif
 123         time_t last_log_time;
 124         /* localhost's name. We print only first 64 chars */
 125         char *hostname;
 126
 127         /* We recv into recvbuf... */
 128         char recvbuf[MAX_READ * (1 + ENABLE_FEATURE_SYSLOGD_DUP)];
 129         /* ...then copy to parsebuf, escaping control chars */
 130         /* (can grow x2 max) */
 131         char parsebuf[MAX_READ*2];
 132         /* ...then sprintf into printbuf, adding timestamp (15 chars),
 133          * host (64), fac.prio (20) to the message */
 134         /* (growth by: 15 + 64 + 20 + delims = ~110) */
 135         char printbuf[MAX_READ*2 + 128];
 136 };
 137
 138 static const struct init_globals init_data = {
 139         .logFile = {
 140                 .path = "/var/log/messages",
 141                 .fd = -1,
 142         },
 143 #ifdef SYSLOGD_MARK
 144         .markInterval = 20 * 60,
 145 #endif
 146         .logLevel = 8,
 147 #if ENABLE_FEATURE_ROTATE_LOGFILE
 148         .logFileSize = 200 * 1024,
 149         .logFileRotate = 1,
 150 #endif
 151 #if ENABLE_FEATURE_IPC_SYSLOG
 152         .shmid = -1,
 153         .s_semid = -1,
 154         .shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024), /* default shm size */
 155         .SMwup = { {1, -1, IPC_NOWAIT} },
 156         .SMwdn = { {0, 0}, {1, 0}, {1, +1} },
 157 #endif
 158 };
 159
 160 #define G (*ptr_to_globals)
 161 #define INIT_G() do { \
 162         SET_PTR_TO_GLOBALS(memcpy(xzalloc(sizeof(G)), &init_data, sizeof(init_data))); \
 163 } while (0)
 164
 165
 166 /* Options */
 167 enum {
 168         OPTBIT_mark = 0, // -m
 169         OPTBIT_nofork, // -n
 170         OPTBIT_outfile, // -O
 171         OPTBIT_loglevel, // -l
 172         OPTBIT_small, // -S
 173         IF_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize   ,)  // -s
 174         IF_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt  ,)  // -b
 175         IF_FEATURE_REMOTE_LOG(    OPTBIT_remotelog  ,)  // -R
 176         IF_FEATURE_REMOTE_LOG(    OPTBIT_locallog   ,)  // -L
 177         IF_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,)  // -C
 178         IF_FEATURE_SYSLOGD_DUP(   OPTBIT_dup        ,)  // -D
 179         IF_FEATURE_SYSLOGD_CFG(   OPTBIT_cfg        ,)  // -f
 180
 181         OPT_mark        = 1 << OPTBIT_mark    ,
 182         OPT_nofork      = 1 << OPTBIT_nofork  ,
 183         OPT_outfile     = 1 << OPTBIT_outfile ,
 184         OPT_loglevel    = 1 << OPTBIT_loglevel,
 185         OPT_small       = 1 << OPTBIT_small   ,
 186         OPT_filesize    = IF_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize   )) + 0,
 187         OPT_rotatecnt   = IF_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt  )) + 0,
 188         OPT_remotelog   = IF_FEATURE_REMOTE_LOG(    (1 << OPTBIT_remotelog  )) + 0,
 189         OPT_locallog    = IF_FEATURE_REMOTE_LOG(    (1 << OPTBIT_locallog   )) + 0,
 190         OPT_circularlog = IF_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
 191         OPT_dup         = IF_FEATURE_SYSLOGD_DUP(   (1 << OPTBIT_dup        )) + 0,
 192         OPT_cfg         = IF_FEATURE_SYSLOGD_CFG(   (1 << OPTBIT_cfg        )) + 0,
 193 };
 194 #define OPTION_STR "m:nO:l:S" \
 195         IF_FEATURE_ROTATE_LOGFILE("s:" ) \
 196         IF_FEATURE_ROTATE_LOGFILE("b:" ) \
 197         IF_FEATURE_REMOTE_LOG(    "R:" ) \
 198         IF_FEATURE_REMOTE_LOG(    "L"  ) \
 199         IF_FEATURE_IPC_SYSLOG(    "C::") \
 200         IF_FEATURE_SYSLOGD_DUP(   "D"  ) \
 201         IF_FEATURE_SYSLOGD_CFG(   "f:"  )
 202 #define OPTION_DECL *opt_m, *opt_l \
 203         IF_FEATURE_ROTATE_LOGFILE(,*opt_s) \
 204         IF_FEATURE_ROTATE_LOGFILE(,*opt_b) \
 205         IF_FEATURE_IPC_SYSLOG(    ,*opt_C = NULL) \
 206         IF_FEATURE_SYSLOGD_CFG(   ,*opt_f = NULL)
 207 #define OPTION_PARAM &opt_m, &(G.logFile.path), &opt_l \
 208         IF_FEATURE_ROTATE_LOGFILE(,&opt_s) \
 209         IF_FEATURE_ROTATE_LOGFILE(,&opt_b) \
 210         IF_FEATURE_REMOTE_LOG(    ,&remoteAddrList) \
 211         IF_FEATURE_IPC_SYSLOG(    ,&opt_C) \
 212         IF_FEATURE_SYSLOGD_CFG(   ,&opt_f)
 213
 214
 215 #if ENABLE_FEATURE_SYSLOGD_CFG
 216 static const CODE* find_by_name(char *name, const CODE* c_set)
 217 {
 218         for (; c_set->c_name; c_set++) {
 219                 if (strcmp(name, c_set->c_name) == 0)
 220                         return c_set;
 221         }
 222         return NULL;
 223 }
 224 #endif
 225 static const CODE* find_by_val(int val, const CODE* c_set)
 226 {
 227         for (; c_set->c_name; c_set++) {
 228                 if (c_set->c_val == val)
 229                         return c_set;
 230         }
 231         return NULL;
 232 }
 233
 234 #if ENABLE_FEATURE_SYSLOGD_CFG
 235 static void parse_syslogdcfg(const char *file)
 236 {
 237         char *t;
 238         logRule_t **pp_rule;
 239         /* tok[0] set of selectors */
 240         /* tok[1] file name */
 241         /* tok[2] has to be NULL */
 242         char *tok[3];
 243         parser_t *parser;
 244
 245         parser = config_open2(file ? file : "/etc/syslog.conf",
 246                                 file ? xfopen_for_read : fopen_or_warn_stdin);
 247         if (!parser)
 248                 /* didn't find default /etc/syslog.conf */
 249                 /* proceed as if we built busybox without config support */
 250                 return;
 251
 252         /* use ptr to ptr to avoid checking whether head was initialized */
 253         pp_rule = &G.log_rules;
 254         /* iterate through lines of config, skipping comments */
 255         while (config_read(parser, tok, 3, 2, "# \t", PARSE_NORMAL | PARSE_MIN_DIE)) {
 256                 char *cur_selector;
 257                 logRule_t *cur_rule;
 258
 259                 /* unexpected trailing token? */
 260                 if (tok[2]) {
 261                         t = tok[2];
 262                         goto cfgerr;
 263                 }
 264
 265                 cur_rule = *pp_rule = xzalloc(sizeof(*cur_rule));
 266
 267                 cur_selector = tok[0];
 268                 /* iterate through selectors: "kern.info;kern.!err;..." */
 269                 do {
 270                         const CODE *code;
 271                         char *next_selector;
 272                         uint8_t negated_prio; /* "kern.!err" */
 273                         uint8_t single_prio;  /* "kern.=err" */
 274                         uint32_t facmap; /* bitmap of enabled facilities */
 275                         uint8_t primap;  /* bitmap of enabled priorities */
 276                         unsigned i;
 277
 278                         next_selector = strchr(cur_selector, ';');
 279                         if (next_selector)
 280                                 *next_selector++ = '\0';
 281
 282                         t = strchr(cur_selector, '.');
 283                         if (!t) {
 284                                 t = cur_selector;
 285                                 goto cfgerr;
 286                         }
 287                         *t++ = '\0'; /* separate facility from priority */
 288
 289                         negated_prio = 0;
 290                         single_prio = 0;
 291                         if (*t == '!') {
 292                                 negated_prio = 1;
 293                                 ++t;
 294                         }
 295                         if (*t == '=') {
 296                                 single_prio = 1;
 297                                 ++t;
 298                         }
 299
 300                         /* parse priority */
 301                         if (*t == '*')
 302                                 primap = 0xff; /* all 8 log levels enabled */
 303                         else {
 304                                 uint8_t priority;
 305                                 code = find_by_name(t, prioritynames);
 306                                 if (!code)
 307                                         goto cfgerr;
 308                                 primap = 0;
 309                                 priority = code->c_val;
 310                                 if (priority == INTERNAL_NOPRI) {
 311                                         /* ensure we take "enabled_facility_priomap[fac] &= 0" branch below */
 312                                         negated_prio = 1;
 313                                 } else {
 314                                         priority = 1 << priority;
 315                                         do {
 316                                                 primap |= priority;
 317                                                 if (single_prio)
 318                                                         break;
 319                                                 priority >>= 1;
 320                                         } while (priority);
 321                                         if (negated_prio)
 322                                                 primap = ~primap;
 323                                 }
 324                         }
 325
 326                         /* parse facility */
 327                         if (*cur_selector == '*')
 328                                 facmap = (1<<LOG_NFACILITIES) - 1;
 329                         else {
 330                                 char *next_facility;
 331                                 facmap = 0;
 332                                 t = cur_selector;
 333                                 /* iterate through facilities: "kern,daemon.<priospec>" */
 334                                 do {
 335                                         next_facility = strchr(t, ',');
 336                                         if (next_facility)
 337                                                 *next_facility++ = '\0';
 338                                         code = find_by_name(t, facilitynames);
 339                                         if (!code)
 340                                                 goto cfgerr;
 341                                         /* "mark" is not a real facility, skip it */
 342                                         if (code->c_val != INTERNAL_MARK)
 343                                                 facmap |= 1<<(LOG_FAC(code->c_val));
 344                                         t = next_facility;
 345                                 } while (t);
 346                         }
 347
 348                         /* merge result with previous selectors */
 349                         for (i = 0; i < LOG_NFACILITIES; ++i) {
 350                                 if (!(facmap & (1<<i)))
 351                                         continue;
 352                                 if (negated_prio)
 353                                         cur_rule->enabled_facility_priomap[i] &= primap;
 354                                 else
 355                                         cur_rule->enabled_facility_priomap[i] |= primap;
 356                         }
 357
 358                         cur_selector = next_selector;
 359                 } while (cur_selector);
 360
 361                 /* check whether current file name was mentioned in previous rules.
 362                  * temporarily use cur_rule as iterator, but *pp_rule still points to
 363                  * currently processing rule entry.
 364                  * NOTE: *pp_rule points to the current (and last in the list) rule.
 365                  */
 366                 for (cur_rule = G.log_rules; cur_rule != *pp_rule; cur_rule = cur_rule->next) {
 367                         if (strcmp(cur_rule->file->path, tok[1]) == 0) {
 368                                 /* found - reuse the same file structure */
 369                                 (*pp_rule)->file = cur_rule->file;
 370                                 cur_rule = *pp_rule;
 371                                 goto found;
 372                         }
 373                 }
 374                 cur_rule->file = xzalloc(sizeof(*cur_rule->file));
 375                 cur_rule->file->fd = -1;
 376                 cur_rule->file->path = xstrdup(tok[1]);
 377  found:
 378                 pp_rule = &cur_rule->next;
 379         }
 380         config_close(parser);
 381         return;
 382
 383  cfgerr:
 384         bb_error_msg_and_die("bad line %d: wrong token '%s'", parser->lineno, t);
 385 }
 386 #endif
 387
 388 /* circular buffer variables/structures */
 389 #if ENABLE_FEATURE_IPC_SYSLOG
 390
 391 #if CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE < 4
 392 #error Sorry, you must set the syslogd buffer size to at least 4KB.
 393 #error Please check CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
 394 #endif
 395
 396 /* our shared key (syslogd.c and logread.c must be in sync) */
 397 enum { KEY_ID = 0x414e4547 }; /* "GENA" */
 398
 399 static void ipcsyslog_cleanup(void)
 400 {
 401         if (G.shmid != -1) {
 402                 shmdt(G.shbuf);
 403         }
 404         if (G.shmid != -1) {
 405                 shmctl(G.shmid, IPC_RMID, NULL);
 406         }
 407         if (G.s_semid != -1) {
 408                 semctl(G.s_semid, 0, IPC_RMID, 0);
 409         }
 410 }
 411
 412 static void ipcsyslog_init(void)
 413 {
 414         if (DEBUG)
 415                 printf("shmget(%x, %d,...)\n", (int)KEY_ID, G.shm_size);
 416
 417         G.shmid = shmget(KEY_ID, G.shm_size, IPC_CREAT | 0644);
 418         if (G.shmid == -1) {
 419                 bb_perror_msg_and_die("shmget");
 420         }
 421
 422         G.shbuf = shmat(G.shmid, NULL, 0);
 423         if (G.shbuf == (void*) -1L) { /* shmat has bizarre error return */
 424                 bb_perror_msg_and_die("shmat");
 425         }
 426
 427         memset(G.shbuf, 0, G.shm_size);
 428         G.shbuf->size = G.shm_size - offsetof(struct shbuf_ds, data) - 1;
 429         /*G.shbuf->tail = 0;*/
 430
 431         /* we'll trust the OS to set initial semval to 0 (let's hope) */
 432         G.s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023);
 433         if (G.s_semid == -1) {
 434                 if (errno == EEXIST) {
 435                         G.s_semid = semget(KEY_ID, 2, 0);
 436                         if (G.s_semid != -1)
 437                                 return;
 438                 }
 439                 bb_perror_msg_and_die("semget");
 440         }
 441 }
 442
 443 /* Write message to shared mem buffer */
 444 static void log_to_shmem(const char *msg)
 445 {
 446         int old_tail, new_tail;
 447         int len;
 448
 449         if (semop(G.s_semid, G.SMwdn, 3) == -1) {
 450                 bb_perror_msg_and_die("SMwdn");
 451         }
 452
 453         /* Circular Buffer Algorithm:
 454          * --------------------------
 455          * tail == position where to store next syslog message.
 456          * tail's max value is (shbuf->size - 1)
 457          * Last byte of buffer is never used and remains NUL.
 458          */
 459         len = strlen(msg) + 1; /* length with NUL included */
 460  again:
 461         old_tail = G.shbuf->tail;
 462         new_tail = old_tail + len;
 463         if (new_tail < G.shbuf->size) {
 464                 /* store message, set new tail */
 465                 memcpy(G.shbuf->data + old_tail, msg, len);
 466                 G.shbuf->tail = new_tail;
 467         } else {
 468                 /* k == available buffer space ahead of old tail */
 469                 int k = G.shbuf->size - old_tail;
 470                 /* copy what fits to the end of buffer, and repeat */
 471                 memcpy(G.shbuf->data + old_tail, msg, k);
 472                 msg += k;
 473                 len -= k;
 474                 G.shbuf->tail = 0;
 475                 goto again;
 476         }
 477         if (semop(G.s_semid, G.SMwup, 1) == -1) {
 478                 bb_perror_msg_and_die("SMwup");
 479         }
 480         if (DEBUG)
 481                 printf("tail:%d\n", G.shbuf->tail);
 482 }
 483 #else
 484 void ipcsyslog_cleanup(void);
 485 void ipcsyslog_init(void);
 486 void log_to_shmem(const char *msg);
 487 #endif /* FEATURE_IPC_SYSLOG */
 488
 489 /* Print a message to the log file. */
 490 static void log_locally(time_t now, char *msg, logFile_t *log_file)
 491 {
 492 #ifdef SYSLOGD_WRLOCK
 493         struct flock fl;
 494 #endif
 495         int len = strlen(msg);
 496
 497         if (log_file->fd >= 0) {
 498                 /* Reopen log file every second. This allows admin
 499                  * to delete the file and not worry about restarting us.
 500                  * This costs almost nothing since it happens
 501                  * _at most_ once a second.
 502                  */
 503                 if (!now)
 504                         now = time(NULL);
 505                 if (G.last_log_time != now) {
 506                         G.last_log_time = now;
 507                         close(log_file->fd);
 508                         goto reopen;
 509                 }
 510         } else {
 511  reopen:
 512                 log_file->fd = open(log_file->path, O_WRONLY | O_CREAT
 513                                         | O_NOCTTY | O_APPEND | O_NONBLOCK,
 514                                         0666);
 515                 if (log_file->fd < 0) {
 516                         /* cannot open logfile? - print to /dev/console then */
 517                         int fd = device_open(DEV_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
 518                         if (fd < 0)
 519                                 fd = 2; /* then stderr, dammit */
 520                         full_write(fd, msg, len);
 521                         if (fd != 2)
 522                                 close(fd);
 523                         return;
 524                 }
 525 #if ENABLE_FEATURE_ROTATE_LOGFILE
 526                 {
 527                         struct stat statf;
 528                         log_file->isRegular = (fstat(log_file->fd, &statf) == 0 && S_ISREG(statf.st_mode));
 529                         /* bug (mostly harmless): can wrap around if file > 4gb */
 530                         log_file->size = statf.st_size;
 531                 }
 532 #endif
 533         }
 534
 535 #ifdef SYSLOGD_WRLOCK
 536         fl.l_whence = SEEK_SET;
 537         fl.l_start = 0;
 538         fl.l_len = 1;
 539         fl.l_type = F_WRLCK;
 540         fcntl(log_file->fd, F_SETLKW, &fl);
 541 #endif
 542
 543 #if ENABLE_FEATURE_ROTATE_LOGFILE
 544         if (G.logFileSize && log_file->isRegular && log_file->size > G.logFileSize) {
 545                 if (G.logFileRotate) { /* always 0..99 */
 546                         int i = strlen(log_file->path) + 3 + 1;
 547                         char oldFile[i];
 548                         char newFile[i];
 549                         i = G.logFileRotate - 1;
 550                         /* rename: f.8 -> f.9; f.7 -> f.8; ... */
 551                         while (1) {
 552                                 sprintf(newFile, "%s.%d", log_file->path, i);
 553                                 if (i == 0) break;
 554                                 sprintf(oldFile, "%s.%d", log_file->path, --i);
 555                                 /* ignore errors - file might be missing */
 556                                 rename(oldFile, newFile);
 557                         }
 558                         /* newFile == "f.0" now */
 559                         rename(log_file->path, newFile);
 560 #ifdef SYSLOGD_WRLOCK
 561                         fl.l_type = F_UNLCK;
 562                         fcntl(log_file->fd, F_SETLKW, &fl);
 563 #endif
 564                         close(log_file->fd);
 565                         goto reopen;
 566                 }
 567                 ftruncate(log_file->fd, 0);
 568         }
 569         log_file->size +=
 570 #endif
 571                         full_write(log_file->fd, msg, len);
 572 #ifdef SYSLOGD_WRLOCK
 573         fl.l_type = F_UNLCK;
 574         fcntl(log_file->fd, F_SETLKW, &fl);
 575 #endif
 576 }
 577
 578 static void parse_fac_prio_20(int pri, char *res20)
 579 {
 580         const CODE *c_pri, *c_fac;
 581
 582         c_fac = find_by_val(LOG_FAC(pri) << 3, facilitynames);
 583         if (c_fac) {
 584                 c_pri = find_by_val(LOG_PRI(pri), prioritynames);
 585                 if (c_pri) {
 586                         snprintf(res20, 20, "%s.%s", c_fac->c_name, c_pri->c_name);
 587                         return;
 588                 }
 589         }
 590         snprintf(res20, 20, "<%d>", pri);
 591 }
 592
 593 /* len parameter is used only for "is there a timestamp?" check.
 594  * NB: some callers cheat and supply len==0 when they know
 595  * that there is no timestamp, short-circuiting the test. */
 596 static void timestamp_and_log(int pri, char *msg, int len)
 597 {
 598         char *timestamp;
 599         time_t now;
 600
 601         /* Jan 18 00:11:22 msg... */
 602         /* 01234567890123456 */
 603         if (len < 16 || msg[3] != ' ' || msg[6] != ' '
 604          || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
 605         ) {
 606                 time(&now);
 607                 timestamp = ctime(&now) + 4; /* skip day of week */
 608         } else {
 609                 now = 0;
 610                 timestamp = msg;
 611                 msg += 16;
 612         }
 613         timestamp[15] = '\0';
 614
 615         if (option_mask32 & OPT_small)
 616                 sprintf(G.printbuf, "%s %s\n", timestamp, msg);
 617         else {
 618                 char res[20];
 619                 parse_fac_prio_20(pri, res);
 620                 sprintf(G.printbuf, "%s %.64s %s %s\n", timestamp, G.hostname, res, msg);
 621         }
 622
 623         /* Log message locally (to file or shared mem) */
 624 #if ENABLE_FEATURE_SYSLOGD_CFG
 625         {
 626                 bool match = 0;
 627                 logRule_t *rule;
 628                 uint8_t facility = LOG_FAC(pri);
 629                 uint8_t prio_bit = 1 << LOG_PRI(pri);
 630
 631                 for (rule = G.log_rules; rule; rule = rule->next) {
 632                         if (rule->enabled_facility_priomap[facility] & prio_bit) {
 633                                 log_locally(now, G.printbuf, rule->file);
 634                                 match = 1;
 635                         }
 636                 }
 637                 if (match)
 638                         return;
 639         }
 640 #endif
 641         if (LOG_PRI(pri) < G.logLevel) {
 642 #if ENABLE_FEATURE_IPC_SYSLOG
 643                 if ((option_mask32 & OPT_circularlog) && G.shbuf) {
 644                         log_to_shmem(msg);
 645                         return;
 646                 }
 647 #endif
 648                 log_locally(now, G.printbuf, &G.logFile);
 649         }
 650 }
 651
 652 static void timestamp_and_log_internal(const char *msg)
 653 {
 654         /* -L, or no -R */
 655         if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_locallog))
 656                 return;
 657         timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)msg, 0);
 658 }
 659
 660 /* tmpbuf[len] is a NUL byte (set by caller), but there can be other,
 661  * embedded NULs. Split messages on each of these NULs, parse prio,
 662  * escape control chars and log each locally. */
 663 static void split_escape_and_log(char *tmpbuf, int len)
 664 {
 665         char *p = tmpbuf;
 666
 667         tmpbuf += len;
 668         while (p < tmpbuf) {
 669                 char c;
 670                 char *q = G.parsebuf;
 671                 int pri = (LOG_USER | LOG_NOTICE);
 672
 673                 if (*p == '<') {
 674                         /* Parse the magic priority number */
 675                         pri = bb_strtou(p + 1, &p, 10);
 676                         if (*p == '>')
 677                                 p++;
 678                         if (pri & ~(LOG_FACMASK | LOG_PRIMASK))
 679                                 pri = (LOG_USER | LOG_NOTICE);
 680                 }
 681
 682                 while ((c = *p++)) {
 683                         if (c == '\n')
 684                                 c = ' ';
 685                         if (!(c & ~0x1f) && c != '\t') {
 686                                 *q++ = '^';
 687                                 c += '@'; /* ^@, ^A, ^B... */
 688                         }
 689                         *q++ = c;
 690                 }
 691                 *q = '\0';
 692
 693                 /* Now log it */
 694                 timestamp_and_log(pri, G.parsebuf, q - G.parsebuf);
 695         }
 696 }
 697
 698 #ifdef SYSLOGD_MARK
 699 static void do_mark(int sig)
 700 {
 701         if (G.markInterval) {
 702                 timestamp_and_log_internal("-- MARK --");
 703                 alarm(G.markInterval);
 704         }
 705 }
 706 #endif
 707
 708 /* Don't inline: prevent struct sockaddr_un to take up space on stack
 709  * permanently */
 710 static NOINLINE int create_socket(void)
 711 {
 712         struct sockaddr_un sunx;
 713         int sock_fd;
 714         char *dev_log_name;
 715
 716 #if ENABLE_FEATURE_SYSTEMD
 717         if (sd_listen_fds() == 1)
 718                 return SD_LISTEN_FDS_START;
 719 #endif
 720
 721         memset(&sunx, 0, sizeof(sunx));
 722         sunx.sun_family = AF_UNIX;
 723
 724         /* Unlink old /dev/log or object it points to. */
 725         /* (if it exists, bind will fail) */
 726         strcpy(sunx.sun_path, "/dev/log");
 727         dev_log_name = xmalloc_follow_symlinks("/dev/log");
 728         if (dev_log_name) {
 729                 safe_strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
 730                 free(dev_log_name);
 731         }
 732         unlink(sunx.sun_path);
 733
 734         sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
 735         xbind(sock_fd, (struct sockaddr *) &sunx, sizeof(sunx));
 736         chmod("/dev/log", 0666);
 737
 738         return sock_fd;
 739 }
 740
 741 #if ENABLE_FEATURE_REMOTE_LOG
 742 static int try_to_resolve_remote(remoteHost_t *rh)
 743 {
 744         if (!rh->remoteAddr) {
 745                 unsigned now = monotonic_sec();
 746
 747                 /* Don't resolve name too often - DNS timeouts can be big */
 748                 if ((now - rh->last_dns_resolve) < DNS_WAIT_SEC)
 749                         return -1;
 750                 rh->last_dns_resolve = now;
 751                 rh->remoteAddr = host2sockaddr(rh->remoteHostname, 514);
 752                 if (!rh->remoteAddr)
 753                         return -1;
 754         }
 755         return xsocket(rh->remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
 756 }
 757 #endif
 758
 759 static void do_syslogd(void) NORETURN;
 760 static void do_syslogd(void)
 761 {
 762         int sock_fd;
 763 #if ENABLE_FEATURE_REMOTE_LOG
 764         llist_t *item;
 765 #endif
 766 #if ENABLE_FEATURE_SYSLOGD_DUP
 767         int last_sz = -1;
 768         char *last_buf;
 769         char *recvbuf = G.recvbuf;
 770 #else
 771 #define recvbuf (G.recvbuf)
 772 #endif
 773
 774         /* Set up signal handlers (so that they interrupt read()) */
 775         signal_no_SA_RESTART_empty_mask(SIGTERM, record_signo);
 776         signal_no_SA_RESTART_empty_mask(SIGINT, record_signo);
 777         //signal_no_SA_RESTART_empty_mask(SIGQUIT, record_signo);
 778         signal(SIGHUP, SIG_IGN);
 779 #ifdef SYSLOGD_MARK
 780         signal(SIGALRM, do_mark);
 781         alarm(G.markInterval);
 782 #endif
 783         sock_fd = create_socket();
 784
 785         if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
 786                 ipcsyslog_init();
 787         }
 788
 789         timestamp_and_log_internal("syslogd started: BusyBox v" BB_VER);
 790
 791         while (!bb_got_signal) {
 792                 ssize_t sz;
 793
 794 #if ENABLE_FEATURE_SYSLOGD_DUP
 795                 last_buf = recvbuf;
 796                 if (recvbuf == G.recvbuf)
 797                         recvbuf = G.recvbuf + MAX_READ;
 798                 else
 799                         recvbuf = G.recvbuf;
 800 #endif
 801  read_again:
 802                 sz = read(sock_fd, recvbuf, MAX_READ - 1);
 803                 if (sz < 0) {
 804                         if (!bb_got_signal)
 805                                 bb_perror_msg("read from /dev/log");
 806                         break;
 807                 }
 808
 809                 /* Drop trailing '\n' and NULs (typically there is one NUL) */
 810                 while (1) {
 811                         if (sz == 0)
 812                                 goto read_again;
 813                         /* man 3 syslog says: "A trailing newline is added when needed".
 814                          * However, neither glibc nor uclibc do this:
 815                          * syslog(prio, "test")   sends "test\0" to /dev/log,
 816                          * syslog(prio, "test\n") sends "test\n\0".
 817                          * IOW: newline is passed verbatim!
 818                          * I take it to mean that it's syslogd's job
 819                          * to make those look identical in the log files. */
 820                         if (recvbuf[sz-1] != '\0' && recvbuf[sz-1] != '\n')
 821                                 break;
 822                         sz--;
 823                 }
 824 #if ENABLE_FEATURE_SYSLOGD_DUP
 825                 if ((option_mask32 & OPT_dup) && (sz == last_sz))
 826                         if (memcmp(last_buf, recvbuf, sz) == 0)
 827                                 continue;
 828                 last_sz = sz;
 829 #endif
 830 #if ENABLE_FEATURE_REMOTE_LOG
 831                 /* Stock syslogd sends it '\n'-terminated
 832                  * over network, mimic that */
 833                 recvbuf[sz] = '\n';
 834
 835                 /* We are not modifying log messages in any way before send */
 836                 /* Remote site cannot trust _us_ anyway and need to do validation again */
 837                 for (item = G.remoteHosts; item != NULL; item = item->link) {
 838                         remoteHost_t *rh = (remoteHost_t *)item->data;
 839
 840                         if (rh->remoteFD == -1) {
 841                                 rh->remoteFD = try_to_resolve_remote(rh);
 842                                 if (rh->remoteFD == -1)
 843                                         continue;
 844                         }
 845
 846                         /* Send message to remote logger.
 847                          * On some errors, close and set remoteFD to -1
 848                          * so that DNS resolution is retried.
 849                          */
 850                         if (sendto(rh->remoteFD, recvbuf, sz+1,
 851                                         MSG_DONTWAIT | MSG_NOSIGNAL,
 852                                         &(rh->remoteAddr->u.sa), rh->remoteAddr->len) == -1
 853                         ) {
 854                                 switch (errno) {
 855                                 case ECONNRESET:
 856                                 case ENOTCONN: /* paranoia */
 857                                 case EPIPE:
 858                                         close(rh->remoteFD);
 859                                         rh->remoteFD = -1;
 860                                         free(rh->remoteAddr);
 861                                         rh->remoteAddr = NULL;
 862                                 }
 863                         }
 864                 }
 865 #endif
 866                 if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
 867                         recvbuf[sz] = '\0'; /* ensure it *is* NUL terminated */
 868                         split_escape_and_log(recvbuf, sz);
 869                 }
 870         } /* while (!bb_got_signal) */
 871
 872         timestamp_and_log_internal("syslogd exiting");
 873         puts("syslogd exiting");
 874         if (ENABLE_FEATURE_IPC_SYSLOG)
 875                 ipcsyslog_cleanup();
 876         kill_myself_with_sig(bb_got_signal);
 877 #undef recvbuf
 878 }
 879
 880 int syslogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 881 int syslogd_main(int argc UNUSED_PARAM, char **argv)
 882 {
 883         int opts;
 884         char OPTION_DECL;
 885 #if ENABLE_FEATURE_REMOTE_LOG
 886         llist_t *remoteAddrList = NULL;
 887 #endif
 888
 889         INIT_G();
 890
 891         /* No non-option params, -R can occur multiple times */
 892         opt_complementary = "=0" IF_FEATURE_REMOTE_LOG(":R::");
 893         opts = getopt32(argv, OPTION_STR, OPTION_PARAM);
 894 #if ENABLE_FEATURE_REMOTE_LOG
 895         while (remoteAddrList) {
 896                 remoteHost_t *rh = xzalloc(sizeof(*rh));
 897                 rh->remoteHostname = llist_pop(&remoteAddrList);
 898                 rh->remoteFD = -1;
 899                 rh->last_dns_resolve = monotonic_sec() - DNS_WAIT_SEC - 1;
 900                 llist_add_to(&G.remoteHosts, rh);
 901         }
 902 #endif
 903
 904 #ifdef SYSLOGD_MARK
 905         if (opts & OPT_mark) // -m
 906                 G.markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
 907 #endif
 908         //if (opts & OPT_nofork) // -n
 909         //if (opts & OPT_outfile) // -O
 910         if (opts & OPT_loglevel) // -l
 911                 G.logLevel = xatou_range(opt_l, 1, 8);
 912         //if (opts & OPT_small) // -S
 913 #if ENABLE_FEATURE_ROTATE_LOGFILE
 914         if (opts & OPT_filesize) // -s
 915                 G.logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
 916         if (opts & OPT_rotatecnt) // -b
 917                 G.logFileRotate = xatou_range(opt_b, 0, 99);
 918 #endif
 919 #if ENABLE_FEATURE_IPC_SYSLOG
 920         if (opt_C) // -Cn
 921                 G.shm_size = xatoul_range(opt_C, 4, INT_MAX/1024) * 1024;
 922 #endif
 923         /* If they have not specified remote logging, then log locally */
 924         if (ENABLE_FEATURE_REMOTE_LOG && !(opts & OPT_remotelog)) // -R
 925                 option_mask32 |= OPT_locallog;
 926 #if ENABLE_FEATURE_SYSLOGD_CFG
 927         parse_syslogdcfg(opt_f);
 928 #endif
 929
 930         /* Store away localhost's name before the fork */
 931         G.hostname = safe_gethostname();
 932         *strchrnul(G.hostname, '.') = '\0';
 933
 934         if (!(opts & OPT_nofork)) {
 935                 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
 936         }
 937         //umask(0); - why??
 938         write_pidfile("/var/run/syslogd.pid");
 939         do_syslogd();
 940         /* return EXIT_SUCCESS; */
 941 }
 942
 943 /* Clean up. Needed because we are included from syslogd_and_logger.c */
 944 #undef DEBUG
 945 #undef SYSLOGD_MARK
 946 #undef SYSLOGD_WRLOCK
 947 #undef G
 948 #undef GLOBALS
 949 #undef INIT_G
 950 #undef OPTION_STR
 951 #undef OPTION_DECL
 952 #undef OPTION_PARAM