xen/tools/misc/xen_log.c

#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>

#include "dom0_defs.h"
#include "mem_defs.h"

#define SILENT_ERRORS_FROM_XEN
#define SYSLOG 1
#define SYSLOGTO LOG_LOCAL5

int logoutput;

void stripit(char *str)
{
    int i;
    for ( i = 0; str[i]; i++ )
        if ( (str[i] == '\n') || (str[i] == '\r') ) 
            str[i] = '\0';
}

void errexit(char *str)
{
    if ( logoutput == SYSLOG )
    {
        stripit(str);
        syslog(LOG_ERR, "%s failed: %d (%m)", str, errno);
    } 
    else 
    {
        printf("%s", str);
    }
    exit(1);
}

void log(char *str)
{
    if ( logoutput == SYSLOG )
    {
        stripit(str);
        syslog(LOG_INFO, "%s", str);
    } 
    else 
    {
        printf("%s", str);
    }
}

void process(void)
{
    dom0_op_t op;
    unsigned char buf[208], obuf[224];
    struct sockaddr_in addr, from;
    int fromlen = sizeof(from);
    int len, fd = socket(PF_INET, SOCK_DGRAM, 0);
    unsigned short int lastport = 0, curport = 0;
    
    if ( fd < 0 )
        errexit("could not open datagram socket");

    memset(&addr, 0, sizeof(addr));
    addr.sin_addr.s_addr = htonl(0xa9fe0100); /* 169.254.1.0 */
    addr.sin_port = htons(666);
    addr.sin_family = AF_INET;

    if ( bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0 )
        errexit("could not bind to local address and port");

    op.cmd = DOM0_GETDOMAININFO;

    while ( (len = recvfrom(fd, buf, sizeof(buf), 0,
                            (struct sockaddr *)&from, &fromlen)) >= 0 )
    {
        curport = ntohs(from.sin_port);
        if ( lastport != curport )
        {
            op.u.getdomaininfo.domain = (int)curport;
            if ( do_dom0_op(&op) < 0 )
                log("Error resolving domain name\n");
            else
                lastport = curport;
        }

        sprintf(obuf, "[%s] %s", op.u.getdomaininfo.name, buf);
        log(obuf);

        fromlen = sizeof(from);
    }
}

void closeall(int fd)
{
    int fdlimit = sysconf(_SC_OPEN_MAX);

    while (fd < fdlimit)
        close(fd++);
}

int daemon(int nochdir, int noclose)
{
    switch (fork())
    {
    case 0:  break;
    case -1: return -1;
    default: _exit(0);
    }

    if (setsid() < 0)
        return -1;

    switch (fork())
    {
    case 0:  break;
    case -1: return -1;
    default: _exit(0);
    }

    if (!nochdir)
        chdir("/");

    if (!noclose)
    {
        closeall(0);
        open("/dev/null",O_RDWR);
        dup(0); dup(0);
    }

    return 0;
}

int main(int argc, char **argv)
{
    int c;

    logoutput = 0;
    opterr = 0;

    while ( (c = getopt (argc, argv, "dh")) != -1 )
    {
        switch(c)
        {
        case 'd':
            logoutput = SYSLOG;
            if (daemon(0,0) < 0)
            {
                errno = 2;
                errexit("daemon");
            } else {
                openlog("xen_log", LOG_PID, SYSLOGTO);
            }
            break;
        case 'h':
            printf("Usage: xen_log [options]\n");
            printf("Capture and display output of xen domains.\n\n");
            printf("  -d       Daemonize and send output to syslog.\n");
            exit(0);
            break;
        }
    }

    process();

    return 0;
}