Syslog server for docker images: outputs everything to stdout

syslogdump.c

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <strings.h>
#include <errno.h>
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#define BUFSIZE 4096
#define DEBUG(...)
//#define DEBUG(...) printf(__VA_ARGS__)

static char pri[8][7] = {
    "emerg", "alert", "crit", "error", "warn", "notice", "info", "debug"
};

static char fac[24][9] = {
    "kern", "user", "mail", "daemon", "auth", "syslog", "lpr", "news", "uucp",
    "cron", "authpriv", "ftp", "kern1", "kern2", "kern3", "kern4", "local0",
    "local1", "local2", "local3", "local4", "local5", "local6", "local7"
};

void failerr(char *what, int when) {
    if (when == -1) {
        perror(what);
        exit(1);
    }
}

void handle_log(char *entry) {
    char *p, c;
    int facpriv = 0;
    p = entry;
    if (*p == '<') {
        while(isdigit(*++p)) {
            facpriv = 10 * facpriv + *p -'0';
        }
        if (*p == '>') {
            ++p;
        }
    }

    printf("<%s.%s> %s\n", fac[facpriv >> 3], pri[facpriv & 7], p);
}

int main() {
    unsigned int fd_listen;
    struct sockaddr_un local;
    char buf[BUFSIZE];

    local.sun_family = AF_UNIX;
    strcpy(local.sun_path, "/dev/log");
    unlink(local.sun_path);

    failerr("socket", (fd_listen = socket(AF_UNIX, SOCK_STREAM, 0)));
    failerr("bind", bind(fd_listen, (struct sockaddr *)&local,
        strlen(local.sun_path) + sizeof(local.sun_family)));
    failerr("listen", listen(fd_listen, 5));

    for(;;) {
        int done, fd_conn, n, t;
        struct sockaddr_un remote;
        t = sizeof(remote);
        failerr("accept", (fd_conn = accept(fd_listen, (struct sockaddr *)&remote, &t)));
        DEBUG("Accepted connection\n");
        done = 0;
        do {
            n = recv(fd_conn, buf, BUFSIZE, 0);
            DEBUG("Received %d bytes of input\n", n);
            if (n <= 0) {
                if (n < 0) perror("recv");
                done = 1;
                DEBUG("Want to close\n");
            } else {
                buf[n] = '\0';
                handle_log(buf);
            }
        } while (!done);
        close(fd_conn);
        DEBUG("Closed connection\n");
    }
}

syslogdump.py

#!/usr/bin/env python

import os
import sys
import socket
import signal
import string

bufsiz = 4096

class SyslogListener(object):
    PRIO = ["emerg", "alert", "crit", "err", "warning", "notice", "info", "debug"]
    FACILITY = ["kern", "user", "mail", "daemon", "auth", "syslog", "lpr", "news",
        "uucp", "cron", "authpriv", "ftp", "ntp", "security", "console", "mark",
        "local0", "local1", "local2", "local3", "local4", "local5", "local6", "local7"]

    def __init__(self, sockname):
        self.sockname = sockname
        self.sock = None
        self.wantstop = False
        self.signals = {}
        self.signals[signal.SIGINT] = "SIGINT"
        self.signals[signal.SIGTERM] = "SIGTERM"
        signal.signal(signal.SIGINT, self.sighandler)
        signal.signal(signal.SIGTERM, self.sighandler)

    def listen(self):
        self.cleanSocketFile
        try:
            sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
            sock.bind(self.sockname)
            self.sock = sock
        except:
            self.generalException("Socket error")

        while self.wantstop != True:
            try:
                data, addr = sock.recvfrom(bufsiz)
                print self.formatData(data, addr)
            except socket.error:
                pass
            except:
                self.generalException("Error")

        self.shutdown
        self.cleanSocketFile

    def generalException(self, message):
        xinfo = sys.exc_info()
        print "{0}: {{1}} {2}, initiating shutdown".format(message, xinfo[0], xinfo[1])
        self.wantstop = True

    def cleanSocketFile(self):
        try:
            os.remove(self.sockname)
        except:
            pass

    def formatData(self, data, addr):
        delim = string.find(data, '>')
        priofac = int(data[1:delim])
        return "<{0}.{1}> {2}".format(self.FACILITY[priofac >> 3],
                                      self.PRIO[priofac & 7], data[delim+1:])

    def sighandler(self, signum, _frame):
        print "Signal {0} caught, initiating shutdown".format(self.signals[signum])
        self.wantstop = True

    def shutdown(self):
        try:
            self.sock.close()
        except:
            pass

if __name__ == '__main__':
    sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)
    listener = SyslogListener((sys.argv[1:2] or ["/dev/log"])[0])
    listener.listen()