syslogd: close/re-resolve/reopen remote sockets on some sendto() errors
[oweals/busybox.git] / sysklogd / syslogd.c
index 38ea3d7ff2e4177907cc94b0c8b2dca0d167468e..37a119b3d7b2cd66e325cdb2195dcb9204373a3b 100644 (file)
@@ -21,7 +21,6 @@
 #include <syslog.h>
 */
 
-#include <paths.h>
 #include <sys/un.h>
 #include <sys/uio.h>
 
  * (semaphores are down but do_mark routine tries to down them again) */
 #undef SYSLOGD_MARK
 
+/* Write locking does not seem to be useful either */
+#undef SYSLOGD_WRLOCK
+
 enum {
-       MAX_READ = 256,
+       MAX_READ = CONFIG_FEATURE_SYSLOGD_READ_BUFFER_SIZE,
        DNS_WAIT_SEC = 2 * 60,
 };
 
@@ -55,6 +57,15 @@ struct shbuf_ds {
        char data[1];   /* data/messages */
 };
 
+#if ENABLE_FEATURE_REMOTE_LOG
+typedef struct {
+       int remoteFD;
+       unsigned last_dns_resolve;
+       len_and_sockaddr *remoteAddr;
+       const char *remoteHostname;
+} remoteHost_t;
+#endif
+
 /* Allows us to have smaller initializer. Ugly. */
 #define GLOBALS \
        const char *logFilePath;                \
@@ -63,7 +74,7 @@ struct shbuf_ds {
        /*int markInterval;*/                   \
        /* level of messages to be logged */    \
        int logLevel;                           \
-USE_FEATURE_ROTATE_LOGFILE( \
+IF_FEATURE_ROTATE_LOGFILE( \
        /* max size of file before rotation */  \
        unsigned logFileSize;                   \
        /* number of rotated message files */   \
@@ -71,12 +82,7 @@ USE_FEATURE_ROTATE_LOGFILE( \
        unsigned curFileSize;                   \
        smallint isRegular;                     \
 ) \
-USE_FEATURE_REMOTE_LOG( \
-       /* udp socket for remote logging */     \
-       int remoteFD;                           \
-       len_and_sockaddr* remoteAddr;           \
-) \
-USE_FEATURE_IPC_SYSLOG( \
+IF_FEATURE_IPC_SYSLOG( \
        int shmid; /* ipc shared memory id */   \
        int s_semid; /* ipc semaphore id */     \
        int shm_size;                           \
@@ -92,10 +98,8 @@ struct globals {
        GLOBALS
 
 #if ENABLE_FEATURE_REMOTE_LOG
-       unsigned last_dns_resolve;
-       char *remoteAddrStr;
+       llist_t *remoteHosts;
 #endif
-
 #if ENABLE_FEATURE_IPC_SYSLOG
        struct shbuf_ds *shbuf;
 #endif
@@ -125,9 +129,6 @@ static const struct init_globals init_data = {
        .logFileSize = 200 * 1024,
        .logFileRotate = 1,
 #endif
-#if ENABLE_FEATURE_REMOTE_LOG
-       .remoteFD = -1,
-#endif
 #if ENABLE_FEATURE_IPC_SYSLOG
        .shmid = -1,
        .s_semid = -1,
@@ -150,41 +151,41 @@ enum {
        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
-       USE_FEATURE_SYSLOGD_DUP(   OPTBIT_dup        ,) // -D
+       IF_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize   ,)  // -s
+       IF_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt  ,)  // -b
+       IF_FEATURE_REMOTE_LOG(    OPTBIT_remotelog  ,)  // -R
+       IF_FEATURE_REMOTE_LOG(    OPTBIT_locallog   ,)  // -L
+       IF_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,)  // -C
+       IF_FEATURE_SYSLOGD_DUP(   OPTBIT_dup        ,)  // -D
 
        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,
-       OPT_dup         = USE_FEATURE_SYSLOGD_DUP(   (1 << OPTBIT_dup        )) + 0,
+       OPT_filesize    = IF_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize   )) + 0,
+       OPT_rotatecnt   = IF_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt  )) + 0,
+       OPT_remotelog   = IF_FEATURE_REMOTE_LOG(    (1 << OPTBIT_remotelog  )) + 0,
+       OPT_locallog    = IF_FEATURE_REMOTE_LOG(    (1 << OPTBIT_locallog   )) + 0,
+       OPT_circularlog = IF_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
+       OPT_dup         = IF_FEATURE_SYSLOGD_DUP(   (1 << OPTBIT_dup        )) + 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::") \
-       USE_FEATURE_SYSLOGD_DUP(   "D"  )
+       IF_FEATURE_ROTATE_LOGFILE("s:" ) \
+       IF_FEATURE_ROTATE_LOGFILE("b:" ) \
+       IF_FEATURE_REMOTE_LOG(    "R:" ) \
+       IF_FEATURE_REMOTE_LOG(    "L"  ) \
+       IF_FEATURE_IPC_SYSLOG(    "C::") \
+       IF_FEATURE_SYSLOGD_DUP(   "D"  )
 #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)
+       IF_FEATURE_ROTATE_LOGFILE(,*opt_s) \
+       IF_FEATURE_ROTATE_LOGFILE(,*opt_b) \
+       IF_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)
+       IF_FEATURE_ROTATE_LOGFILE(,&opt_s) \
+       IF_FEATURE_ROTATE_LOGFILE(,&opt_b) \
+       IF_FEATURE_REMOTE_LOG(    ,&remoteAddrList) \
+       IF_FEATURE_IPC_SYSLOG(    ,&opt_C)
 
 
 /* circular buffer variables/structures */
@@ -291,7 +292,9 @@ void log_to_shmem(const char *msg);
 /* Print a message to the log file. */
 static void log_locally(time_t now, char *msg)
 {
+#ifdef SYSLOGD_WRLOCK
        struct flock fl;
+#endif
        int len = strlen(msg);
 
 #if ENABLE_FEATURE_IPC_SYSLOG
@@ -301,17 +304,23 @@ static void log_locally(time_t now, char *msg)
        }
 #endif
        if (G.logFD >= 0) {
+               /* Reopen log file every second. This allows admin
+                * to delete the file and not worry about restarting us.
+                * This costs almost nothing since it happens
+                * _at most_ once a second.
+                */
                if (!now)
                        now = time(NULL);
                if (G.last_log_time != now) {
-                       G.last_log_time = now; /* reopen log file every second */
+                       G.last_log_time = now;
                        close(G.logFD);
                        goto reopen;
                }
        } else {
  reopen:
-               G.logFD = device_open(G.logFilePath, O_WRONLY | O_CREAT
-                                       | O_NOCTTY | O_APPEND | O_NONBLOCK);
+               G.logFD = open(G.logFilePath, O_WRONLY | O_CREAT
+                                       | O_NOCTTY | O_APPEND | O_NONBLOCK,
+                                       0666);
                if (G.logFD < 0) {
                        /* cannot open logfile? - print to /dev/console then */
                        int fd = device_open(DEV_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
@@ -332,11 +341,13 @@ static void log_locally(time_t now, char *msg)
 #endif
        }
 
+#ifdef SYSLOGD_WRLOCK
        fl.l_whence = SEEK_SET;
        fl.l_start = 0;
        fl.l_len = 1;
        fl.l_type = F_WRLCK;
        fcntl(G.logFD, F_SETLKW, &fl);
+#endif
 
 #if ENABLE_FEATURE_ROTATE_LOGFILE
        if (G.logFileSize && G.isRegular && G.curFileSize > G.logFileSize) {
@@ -355,8 +366,10 @@ static void log_locally(time_t now, char *msg)
                        }
                        /* newFile == "f.0" now */
                        rename(G.logFilePath, newFile);
+#ifdef SYSLOGD_WRLOCK
                        fl.l_type = F_UNLCK;
                        fcntl(G.logFD, F_SETLKW, &fl);
+#endif
                        close(G.logFD);
                        goto reopen;
                }
@@ -365,8 +378,10 @@ static void log_locally(time_t now, char *msg)
        G.curFileSize +=
 #endif
                        full_write(G.logFD, msg, len);
+#ifdef SYSLOGD_WRLOCK
        fl.l_type = F_UNLCK;
        fcntl(G.logFD, F_SETLKW, &fl);
+#endif
 }
 
 static void parse_fac_prio_20(int pri, char *res20)
@@ -406,6 +421,8 @@ static void timestamp_and_log(int pri, char *msg, int len)
        char *timestamp;
        time_t now;
 
+       /* Jan 18 00:11:22 msg... */
+       /* 01234567890123456 */
        if (len < 16 || msg[3] != ' ' || msg[6] != ' '
         || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
        ) {
@@ -432,6 +449,7 @@ static void timestamp_and_log(int pri, char *msg, int len)
 
 static void timestamp_and_log_internal(const char *msg)
 {
+       /* -L, or no -R */
        if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_locallog))
                return;
        timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)msg, 0);
@@ -476,15 +494,6 @@ static void split_escape_and_log(char *tmpbuf, int len)
        }
 }
 
-static void quit_signal(int sig)
-{
-       timestamp_and_log_internal("syslogd exiting");
-       puts("syslogd exiting");
-       if (ENABLE_FEATURE_IPC_SYSLOG)
-               ipcsyslog_cleanup();
-       kill_myself_with_sig(sig);
-}
-
 #ifdef SYSLOGD_MARK
 static void do_mark(int sig)
 {
@@ -524,20 +533,20 @@ static NOINLINE int create_socket(void)
 }
 
 #if ENABLE_FEATURE_REMOTE_LOG
-static int try_to_resolve_remote(void)
+static int try_to_resolve_remote(remoteHost_t *rh)
 {
-       if (!G.remoteAddr) {
+       if (!rh->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)
+               if ((now - rh->last_dns_resolve) < DNS_WAIT_SEC)
                        return -1;
-               G.last_dns_resolve = now;
-               G.remoteAddr = host2sockaddr(G.remoteAddrStr, 514);
-               if (!G.remoteAddr)
+               rh->last_dns_resolve = now;
+               rh->remoteAddr = host2sockaddr(rh->remoteHostname, 514);
+               if (!rh->remoteAddr)
                        return -1;
        }
-       return socket(G.remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
+       return xsocket(rh->remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
 }
 #endif
 
@@ -545,6 +554,9 @@ static void do_syslogd(void) NORETURN;
 static void do_syslogd(void)
 {
        int sock_fd;
+#if ENABLE_FEATURE_REMOTE_LOG
+       llist_t *item;
+#endif
 #if ENABLE_FEATURE_SYSLOGD_DUP
        int last_sz = -1;
        char *last_buf;
@@ -553,14 +565,11 @@ static void do_syslogd(void)
 #define recvbuf (G.recvbuf)
 #endif
 
-       /* Set up signal handlers */
-       bb_signals(0
-               + (1 << SIGINT)
-               + (1 << SIGTERM)
-               + (1 << SIGQUIT)
-               , quit_signal);
+       /* Set up signal handlers (so that they interrupt read()) */
+       signal_no_SA_RESTART_empty_mask(SIGTERM, record_signo);
+       signal_no_SA_RESTART_empty_mask(SIGINT, record_signo);
+       //signal_no_SA_RESTART_empty_mask(SIGQUIT, record_signo);
        signal(SIGHUP, SIG_IGN);
-       /* signal(SIGCHLD, SIG_IGN); - why? */
 #ifdef SYSLOGD_MARK
        signal(SIGALRM, do_mark);
        alarm(G.markInterval);
@@ -573,7 +582,7 @@ static void do_syslogd(void)
 
        timestamp_and_log_internal("syslogd started: BusyBox v" BB_VER);
 
-       for (;;) {
+       while (!bb_got_signal) {
                ssize_t sz;
 
 #if ENABLE_FEATURE_SYSLOGD_DUP
@@ -584,9 +593,12 @@ static void do_syslogd(void)
                        recvbuf = G.recvbuf;
 #endif
  read_again:
-               sz = safe_read(sock_fd, recvbuf, MAX_READ - 1);
-               if (sz < 0)
-                       bb_perror_msg_and_die("read from /dev/log");
+               sz = read(sock_fd, recvbuf, MAX_READ - 1);
+               if (sz < 0) {
+                       if (!bb_got_signal)
+                               bb_perror_msg("read from /dev/log");
+                       break;
+               }
 
                /* Drop trailing '\n' and NULs (typically there is one NUL) */
                while (1) {
@@ -610,59 +622,92 @@ static void do_syslogd(void)
                last_sz = sz;
 #endif
 #if ENABLE_FEATURE_REMOTE_LOG
+               /* Stock syslogd sends it '\n'-terminated
+                * over network, mimic that */
+               recvbuf[sz] = '\n';
+
                /* 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;
+               for (item = G.remoteHosts; item != NULL; item = item->link) {
+                       remoteHost_t *rh = (remoteHost_t *)item->data;
+
+                       if (rh->remoteFD == -1) {
+                               rh->remoteFD = try_to_resolve_remote(rh);
+                               if (rh->remoteFD == -1)
+                                       continue;
+                       }
+
+                       /* Send message to remote logger.
+                        * On some errors, close and set remoteFD to -1
+                        * so that DNS resolution is retried.
+                        */
+                       if (sendto(rh->remoteFD, recvbuf, sz+1,
+                                       MSG_DONTWAIT | MSG_NOSIGNAL,
+                                       &(rh->remoteAddr->u.sa), rh->remoteAddr->len) == -1
+                       ) {
+                               switch (errno) {
+                               case ECONNRESET:
+                               case ENOTCONN: /* paranoia */
+                               case EPIPE:
+                                       close(rh->remoteFD);
+                                       rh->remoteFD = -1;
+                                       free(rh->remoteAddr);
+                                       rh->remoteAddr = NULL;
+                               }
                        }
-                       /* Stock syslogd sends it '\n'-terminated
-                        * over network, mimic that */
-                       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, recvbuf, sz+1, MSG_DONTWAIT,
-                                   &G.remoteAddr->u.sa, G.remoteAddr->len);
- no_luck: ;
                }
 #endif
                if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
                        recvbuf[sz] = '\0'; /* ensure it *is* NUL terminated */
                        split_escape_and_log(recvbuf, sz);
                }
-       } /* for (;;) */
+       } /* while (!bb_got_signal) */
+
+       timestamp_and_log_internal("syslogd exiting");
+       puts("syslogd exiting");
+       if (ENABLE_FEATURE_IPC_SYSLOG)
+               ipcsyslog_cleanup();
+       kill_myself_with_sig(bb_got_signal);
 #undef recvbuf
 }
 
 int syslogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int syslogd_main(int argc UNUSED_PARAM, char **argv)
 {
+       int opts;
        char OPTION_DECL;
+#if ENABLE_FEATURE_REMOTE_LOG
+       llist_t *remoteAddrList = NULL;
+#endif
 
        INIT_G();
+
+       /* No non-option params, -R can occur multiple times */
+       opt_complementary = "=0" IF_FEATURE_REMOTE_LOG(":R::");
+       opts = getopt32(argv, OPTION_STR, OPTION_PARAM);
 #if ENABLE_FEATURE_REMOTE_LOG
-       G.last_dns_resolve = monotonic_sec() - DNS_WAIT_SEC - 1;
+       while (remoteAddrList) {
+               remoteHost_t *rh = xzalloc(sizeof(*rh));
+               rh->remoteHostname = llist_pop(&remoteAddrList);
+               rh->remoteFD = -1;
+               rh->last_dns_resolve = monotonic_sec() - DNS_WAIT_SEC - 1;
+               llist_add_to(&G.remoteHosts, rh);
+       }
 #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
+       if (opts & 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
+       //if (opts & OPT_nofork) // -n
+       //if (opts & OPT_outfile) // -O
+       if (opts & OPT_loglevel) // -l
                G.logLevel = xatou_range(opt_l, 1, 8);
-       //if (option_mask32 & OPT_small) // -S
+       //if (opts & OPT_small) // -S
 #if ENABLE_FEATURE_ROTATE_LOGFILE
-       if (option_mask32 & OPT_filesize) // -s
+       if (opts & OPT_filesize) // -s
                G.logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
-       if (option_mask32 & OPT_rotatecnt) // -b
+       if (opts & OPT_rotatecnt) // -b
                G.logFileRotate = xatou_range(opt_b, 0, 99);
 #endif
 #if ENABLE_FEATURE_IPC_SYSLOG
@@ -671,23 +716,26 @@ int syslogd_main(int argc UNUSED_PARAM, char **argv)
 #endif
 
        /* If they have not specified remote logging, then log locally */
-       if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_remotelog))
+       if (ENABLE_FEATURE_REMOTE_LOG && !(opts & OPT_remotelog)) // -R
                option_mask32 |= OPT_locallog;
 
        /* Store away localhost's name before the fork */
        G.hostname = safe_gethostname();
        *strchrnul(G.hostname, '.') = '\0';
 
-       if (!(option_mask32 & OPT_nofork)) {
+       if (!(opts & OPT_nofork)) {
                bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
        }
-       umask(0);
+       //umask(0); - why??
        write_pidfile("/var/run/syslogd.pid");
        do_syslogd();
        /* return EXIT_SUCCESS; */
 }
 
 /* Clean up. Needed because we are included from syslogd_and_logger.c */
+#undef DEBUG
+#undef SYSLOGD_MARK
+#undef SYSLOGD_WRLOCK
 #undef G
 #undef GLOBALS
 #undef INIT_G