/*** $Id: servaccept.c,v 1.5 2003/09/04 06:02:53 weiym Exp $** ** servaccept.c: accept connection from clients.** ** Copyright (C) 2003 Feynman Software** Copyright (C) 2000 ~ 2002 Wei Yongming.**** Current maintainer: Wei Yongming.**** Create date: 2000/12/19**** NOTE: The idea comes from sample code in APUE.*//*** This program is free software; you can redistribute it and/or modify** it under the terms of the GNU General Public License as published by** the Free Software Foundation; either version 2 of the License, or** (at your option) any later version.**** This program is distributed in the hope that it will be useful,** but WITHOUT ANY WARRANTY; without even the implied warranty of** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the** GNU General Public License for more details.**** You should have received a copy of the GNU General Public License** along with this program; if not, write to the Free Software** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA*//*** TODO:*/#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/socket.h>#include <sys/stat.h>#include <sys/un.h>#include <stddef.h>#include <time.h>#include <unistd.h>#include "ourhdr.h"#define    STALE    30    /* client's name can't be older than this (sec) *//* Wait for a client connection to arrive, and accept it. * We also obtain the client's pid from the pathname * that it must bind before calling us. *//* returns new fd if all OK, < 0 on error */int serv_accept (int listenfd, pid_t *pidptr, uid_t *uidptr){    int                clifd, len;    time_t             staletime;    struct sockaddr_un unix_addr;    struct stat        statbuf;    const char*        pid_str;    len = sizeof (unix_addr);    if ( (clifd = accept (listenfd, (struct sockaddr *) &unix_addr, &len)) < 0)        return (-1);        /* often errno=EINTR, if signal caught */    /* obtain the client's uid from its calling address */    len -= /* th sizeof(unix_addr.sun_len) - */ sizeof(unix_addr.sun_family);                    /* len of pathname */    unix_addr.sun_path[len] = 0;            /* null terminate */    if (stat(unix_addr.sun_path, &statbuf) < 0)        return(-2);#ifdef    S_ISSOCK    /* not defined for SVR4 */    if (S_ISSOCK(statbuf.st_mode) == 0)        return(-3);        /* not a socket */#endif    if ((statbuf.st_mode & (S_IRWXG | S_IRWXO)) ||        (statbuf.st_mode & S_IRWXU) != S_IRWXU)          return(-4);    /* is not rwx------ */    staletime = time(NULL) - STALE;    if (statbuf.st_atime < staletime ||        statbuf.st_ctime < staletime ||        statbuf.st_mtime < staletime)          return(-5);    /* i-node is too old */    if (uidptr != NULL)        *uidptr = statbuf.st_uid;    /* return uid of caller */    /* get pid of client from sun_path */    pid_str = strrchr (unix_addr.sun_path, '/');    pid_str++;    *pidptr = atoi (pid_str);        unlink (unix_addr.sun_path);        /* we're done with pathname now */    return (clifd);}