syslogd: don't die if remote host's IP cannot be resolved.

retry resolutions every two minutes instead.

function                                             old     new   delta
syslogd_main                                         865     904     +39
timestamp_and_log                                    324     313     -11
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 39/-11)             Total: 28 bytes

1 files changed, 63 insertions, 37 deletions

diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 5998732bd..7000e9301 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -42,7 +42,10 @@
  * (semaphores are down but do_mark routine tries to down them again) */
 #undef SYSLOGD_MARK
 
-enum { MAX_READ = 256 };
+enum {
+        MAX_READ = 256,
+        DNS_WAIT_SEC = 2 * 60,
+};
 
 /* Semaphore operation structures */
 struct shbuf_ds {
@@ -86,6 +89,12 @@ struct init_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
@@ -128,6 +137,9 @@ static const struct init_globals init_data = {
 };
 
 #define G (*ptr_to_globals)
+#define INIT_G() do { \
+        PTR_TO_GLOBALS = memcpy(xzalloc(sizeof(G)), &init_data, sizeof(init_data)); \
+} while (0)
 
 
 /* Options */
@@ -140,7 +152,7 @@ enum {
         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_localtoo   ,) // -L
+        USE_FEATURE_REMOTE_LOG(    OPTBIT_locallog   ,) // -L
         USE_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,) // -C
 
         OPT_mark        = 1 << OPTBIT_mark    ,
@@ -151,7 +163,7 @@ enum {
         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_localtoo   )) + 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" \
@@ -163,12 +175,11 @@ enum {
 #define OPTION_DECL *opt_m, *opt_l \
         USE_FEATURE_ROTATE_LOGFILE(,*opt_s) \
         USE_FEATURE_ROTATE_LOGFILE(,*opt_b) \
-        USE_FEATURE_REMOTE_LOG(    ,*opt_R) \
         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(    ,&opt_R) \
+        USE_FEATURE_REMOTE_LOG(    ,&G.remoteAddrStr) \
         USE_FEATURE_IPC_SYSLOG(    ,&opt_C)
 
 
@@ -387,6 +398,9 @@ static void timestamp_and_log(int pri, char *msg, int len)
 {
         char *timestamp;
 
+        if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_locallog))
+                return;
+
         if (len < 16 || msg[3] != ' ' || msg[6] != ' '
          || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
         ) {
@@ -400,18 +414,14 @@ static void timestamp_and_log(int pri, char *msg, int len)
         timestamp[15] = '\0';
 
         /* Log message locally (to file or shared mem) */
-        if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
-                if (LOG_PRI(pri) < G.logLevel) {
-                        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_locally(G.printbuf);
-                }
+        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_locally(G.printbuf);
 }
 
 static void split_escape_and_log(char *tmpbuf, int len)
@@ -443,8 +453,10 @@ static void split_escape_and_log(char *tmpbuf, int len)
                         *q++ = c;
                 }
                 *q = '\0';
+
                 /* Now log it */
-                timestamp_and_log(pri, G.parsebuf, q - G.parsebuf);
+                if (LOG_PRI(pri) < G.logLevel)
+                        timestamp_and_log(pri, G.parsebuf, q - G.parsebuf);
         }
 }
 
@@ -495,6 +507,24 @@ static NOINLINE int create_socket(void)
         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->sa.sa_family, SOCK_DGRAM, 0);
+}
+#endif
+
 static void do_syslogd(void) ATTRIBUTE_NORETURN;
 static void do_syslogd(void)
 {
@@ -505,10 +535,7 @@ static void do_syslogd(void)
         signal(SIGTERM, quit_signal);
         signal(SIGQUIT, quit_signal);
         signal(SIGHUP, SIG_IGN);
-        signal(SIGCHLD, SIG_IGN);
-#ifdef SIGCLD
-        signal(SIGCLD, SIG_IGN);
-#endif
+        /* signal(SIGCHLD, SIG_IGN); - why? */
 #ifdef SYSLOGD_MARK
         signal(SIGALRM, do_mark);
         alarm(G.markInterval);
@@ -554,19 +581,21 @@ static void do_syslogd(void)
 #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.remoteAddr) {
+                if (G.remoteAddrStr) {
                         if (-1 == G.remoteFD) {
-                                G.remoteFD = socket(G.remoteAddr->sa.sa_family, SOCK_DGRAM, 0);
-                        }
-                        if (-1 != G.remoteFD) {
-                                /* send message to remote logger, ignore possible error */
-                                sendto(G.remoteFD, G.recvbuf, sz, MSG_DONTWAIT,
-                                        &G.remoteAddr->sa, G.remoteAddr->len);
+                                G.remoteFD = try_to_resolve_remote();
+                                if (-1 == G.remoteFD)
+                                        goto no_luck;
                         }
+                        /* send message to remote logger, ignore possible error */
+                        sendto(G.remoteFD, G.recvbuf, sz, MSG_DONTWAIT,
+                                    &G.remoteAddr->sa, G.remoteAddr->len);
+ no_luck: ;
                 }
 #endif
-                split_escape_and_log(G.recvbuf, sz);
-        } /* for */
+                if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog))
+                        split_escape_and_log(G.recvbuf, sz);
+        } /* for (;;) */
 }
 
 int syslogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@@ -575,7 +604,10 @@ int syslogd_main(int argc, char **argv)
         char OPTION_DECL;
         char *p;
 
-        PTR_TO_GLOBALS = memcpy(xzalloc(sizeof(G)), &init_data, sizeof(init_data));
+        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 */
@@ -595,12 +627,6 @@ int syslogd_main(int argc, char **argv)
         if (option_mask32 & OPT_rotatecnt) // -b
                 G.logFileRotate = xatou_range(opt_b, 0, 99);
 #endif
-#if ENABLE_FEATURE_REMOTE_LOG
-        if (option_mask32 & OPT_remotelog) { // -R
-                G.remoteAddr = xhost2sockaddr(opt_R, 514);
-        }
-        //if (option_mask32 & OPT_locallog) // -L
-#endif
 #if ENABLE_FEATURE_IPC_SYSLOG
         if (opt_C) // -Cn
                 G.shm_size = xatoul_range(opt_C, 4, INT_MAX/1024) * 1024;