source: MondoRescue/branches/3.2/mindi-busybox/networking/isrv_identd.c@ 3232

/* vi: set sw=4 ts=4: */
/*
 * Fake identd server.
 *
 * Copyright (C) 2007 Denys Vlasenko
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */

//usage:#define fakeidentd_trivial_usage
//usage:       "[-fiw] [-b ADDR] [STRING]"
//usage:#define fakeidentd_full_usage "\n\n"
//usage:       "Provide fake ident (auth) service\n"
//usage:     "\n    -f  Run in foreground"
//usage:     "\n    -i  Inetd mode"
//usage:     "\n    -w  Inetd 'wait' mode"
//usage:     "\n    -b ADDR Bind to specified address"
//usage:     "\n    STRING  Ident answer string (default: nobody)"

#include "libbb.h"
#include <syslog.h>
#include "isrv.h"

enum { TIMEOUT = 20 };

typedef struct identd_buf_t {
    int pos;
    int fd_flag;
    char buf[64 - 2*sizeof(int)];
} identd_buf_t;

#define bogouser bb_common_bufsiz1

static int new_peer(isrv_state_t *state, int fd)
{
    int peer;
    identd_buf_t *buf = xzalloc(sizeof(*buf));

    peer = isrv_register_peer(state, buf);
    if (peer < 0)
        return 0; /* failure */
    if (isrv_register_fd(state, peer, fd) < 0)
        return peer; /* failure, unregister peer */

    buf->fd_flag = fcntl(fd, F_GETFL) | O_NONBLOCK;
    isrv_want_rd(state, fd);
    return 0;
}

static int do_rd(int fd, void **paramp)
{
    identd_buf_t *buf = *paramp;
    char *cur, *p;
    int retval = 0; /* session is ok (so far) */
    int sz;

    cur = buf->buf + buf->pos;

    if (buf->fd_flag & O_NONBLOCK)
        fcntl(fd, F_SETFL, buf->fd_flag);
    sz = safe_read(fd, cur, sizeof(buf->buf) - buf->pos);

    if (sz < 0) {
        if (errno != EAGAIN)
            goto term; /* terminate this session if !EAGAIN */
        goto ok;
    }

    buf->pos += sz;
    buf->buf[buf->pos] = '\0';
    p = strpbrk(cur, "\r\n");
    if (p)
        *p = '\0';
    if (!p && sz && buf->pos <= (int)sizeof(buf->buf))
        goto ok;
    /* Terminate session. If we are in server mode, then
     * fd is still in nonblocking mode - we never block here */
    if (fd == 0) fd++; /* inetd mode? then write to fd 1 */
    fdprintf(fd, "%s : USERID : UNIX : %s\r\n", buf->buf, bogouser);
 term:
    free(buf);
    retval = 1; /* terminate */
 ok:
    if (buf->fd_flag & O_NONBLOCK)
        fcntl(fd, F_SETFL, buf->fd_flag & ~O_NONBLOCK);
    return retval;
}

static int do_timeout(void **paramp UNUSED_PARAM)
{
    return 1; /* terminate session */
}

static void inetd_mode(void)
{
    identd_buf_t *buf = xzalloc(sizeof(*buf));
    /* buf->pos = 0; - xzalloc did it */
    /* We do NOT want nonblocking I/O here! */
    /* buf->fd_flag = 0; - xzalloc did it */
    do
        alarm(TIMEOUT);
    while (do_rd(0, (void*)&buf) == 0);
}

int fakeidentd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int fakeidentd_main(int argc UNUSED_PARAM, char **argv)
{
    enum {
        OPT_foreground = 0x1,
        OPT_inetd      = 0x2,
        OPT_inetdwait  = 0x4,
        OPT_fiw        = 0x7,
        OPT_bindaddr   = 0x8,
    };

    const char *bind_address = NULL;
    unsigned opt;
    int fd;

    opt = getopt32(argv, "fiwb:", &bind_address);
    strcpy(bogouser, "nobody");
    if (argv[optind])
        strncpy(bogouser, argv[optind], sizeof(bogouser));

    /* Daemonize if no -f and no -i and no -w */
    if (!(opt & OPT_fiw))
        bb_daemonize_or_rexec(0, argv);

    /* Where to log in inetd modes? "Classic" inetd
     * probably has its stderr /dev/null'ed (we need log to syslog?),
     * but daemontools-like utilities usually expect that children
     * log to stderr. I like daemontools more. Go their way.
     * (Or maybe we need yet another option "log to syslog") */
    if (!(opt & OPT_fiw) /* || (opt & OPT_syslog) */) {
        openlog(applet_name, LOG_PID, LOG_DAEMON);
        logmode = LOGMODE_SYSLOG;
    }

    if (opt & OPT_inetd) {
        inetd_mode();
        return 0;
    }

    /* Ignore closed connections when writing */
    signal(SIGPIPE, SIG_IGN);

    fd = 0;
    if (!(opt & OPT_inetdwait)) {
        fd = create_and_bind_stream_or_die(bind_address,
                bb_lookup_port("identd", "tcp", 113));
        xlisten(fd, 5);
    }

    isrv_run(fd, new_peer, do_rd, /*do_wr:*/ NULL, do_timeout,
            TIMEOUT, (opt & OPT_inetdwait) ? TIMEOUT : 0);
    return 0;
}