util_funcs.c

开发snmp的开发包有两个开放的SNMP开发库

/*
 * util_funcs.c
 */
/*
 * Portions of this file are copyrighted by:
 * Copyright Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * Use is subject to license terms specified in the COPYING file
 * distributed with the Net-SNMP package.
 */

#include <net-snmp/net-snmp-config.h>

#if HAVE_IO_H
#include <io.h>
#endif
#include <stdio.h>
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_MALLOC_H
#include <malloc.h>
#endif
#include <sys/types.h>
#ifdef __alpha
#ifndef _BSD
#define _BSD
#define _myBSD
#endif
#endif
#if HAVE_SYS_WAIT_H
# include <sys/wait.h>
#endif
#ifdef __alpha
#ifdef _myBSD
#undef _BSD
#undef _myBSD
#endif
#endif
#ifndef WEXITSTATUS
# define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
#endif
#ifndef WIFEXITED
# define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
#endif
#if TIME_WITH_SYS_TIME
# ifdef WIN32
#  include <sys/timeb.h>
# else
#  include <sys/time.h>
# endif
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif
#include <errno.h>
#include <signal.h>
#if HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#include <ctype.h>
#if HAVE_WINSOCK_H
#include <winsock.h>
#endif
#if HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#if HAVE_BASETSD_H
#include <basetsd.h>
#define ssize_t SSIZE_T
#endif
#if HAVE_RAISE
#define alarm raise
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>

#include "struct.h"
#include "util_funcs.h"
#include "utilities/execute.h"

#if HAVE_LIMITS_H
#include "limits.h"
#endif
#ifdef USING_UCD_SNMP_ERRORMIB_MODULE
#include "ucd-snmp/errormib.h"
#else
#define setPerrorstatus(x) snmp_log_perror(x)
#endif


#ifdef NETSNMP_EXCACHETIME
static long     cachetime;
#endif

extern int      numprocs, numextens;

void
Exit(int var)
{
    snmp_log(LOG_ERR, "Server Exiting with code %d\n", var);
    exit(var);
}

/** deprecated, use netsnmp_mktemp instead */
const char *
make_tempfile(void)
{
    static char     name[32];
    int             fd = -1;

    strcpy(name, get_temp_file_pattern());
#ifdef HAVE_MKSTEMP
    fd = mkstemp(name);
#else
    if (mktemp(name)) {
# ifndef WIN32        
        fd = open(name, O_CREAT | O_EXCL | O_WRONLY);
# else
        /*
          Win32 needs _S_IREAD | _S_IWRITE to set permissions on file after closing
         */
        fd = _open(name, _O_CREAT, _S_IREAD | _S_IWRITE | _O_EXCL | _O_WRONLY);
# endif
    }
#endif
    if (fd >= 0) {
        close(fd);
        DEBUGMSGTL(("make_tempfile", "temp file created: %s\n", name));
        return name;
    }
    snmp_log(LOG_ERR,"make_tempfile: error creating file %s\n", name);
    return NULL;
}

int
shell_command(struct extensible *ex)
{
#if HAVE_SYSTEM
    const char     *ofname;
    char            shellline[STRMAX];
    FILE           *shellout;

    ofname = make_tempfile();
    if (ofname == NULL) {
        ex->output[0] = 0;
        ex->result = 127;
        return ex->result;
    }

    snprintf(shellline, sizeof(shellline), "%s > %s", ex->command, ofname);
    shellline[ sizeof(shellline)-1 ] = 0;
    ex->result = system(shellline);
    ex->result = WEXITSTATUS(ex->result);
    shellout = fopen(ofname, "r");
    if (shellout != NULL) {
        if (fgets(ex->output, sizeof(ex->output), shellout) == NULL) {
            ex->output[0] = 0;
        }
        fclose(shellout);
    }
    unlink(ofname);
#else
    ex->output[0] = 0;
    ex->result = 0;
#endif
    return (ex->result);
}

#define MAXOUTPUT 300

int
exec_command(struct extensible *ex)
{
#if defined (HAVE_EXECV) || defined (WIN32)
    int             fd;
    FILE           *file;

    if ((fd = get_exec_output(ex)) != -1) {
        file = fdopen(fd, "r");
        if (fgets(ex->output, sizeof(ex->output), file) == NULL) {
            ex->output[0] = 0;
        }
        fclose(file);
        wait_on_exec(ex);
    } else
#endif /* HAVE_EXECV */
    {
        ex->output[0] = 0;
        ex->result = 0;
    }
    return (ex->result);
}

struct extensible *
get_exten_instance(struct extensible *exten, size_t inst)
{
    int             i;

    if (exten == NULL)
        return (NULL);
    for (i = 1; i != (int) inst && exten != NULL; i++)
        exten = exten->next;
    return (exten);
}

void
wait_on_exec(struct extensible *ex)
{
#if defined(WIN32) && !defined (mingw32)
  int rc;
  if (ex->tid != 0 && ex->pid != 0) {
    HANDLE hThread = (HANDLE) ex->tid;
    HANDLE hProcess = (HANDLE) ex->pid;
    rc = WaitForSingleObject(hProcess, NETSNMP_TIMEOUT_WAITFORSINGLEOBJECT);
    DEBUGMSGT(("exec:wait_on_exec","WaitForSingleObject rc=(%d)\n",rc ));
    rc = CloseHandle( hThread );
    DEBUGMSGT(("exec:wait_on_exec","CloseHandle hThread=(%d)\n",rc ));
    rc = CloseHandle( hProcess );
    DEBUGMSGT(("exec:wait_on_exec","CloseHandle hProcess=(%d)\n",rc ));
    ex->pid = 0;
    ex->tid = 0;
  }
#else
#ifndef NETSNMP_EXCACHETIME
    if (ex->pid && waitpid(ex->pid, &ex->result, 0) < 0) {
        setPerrorstatus("waitpid");
    }
    ex->pid = 0;
#endif  /* NETSNMP_EXCACHETIME */
#endif  /* WIN32 */
}

#define MAXARGS 30

int
get_exec_output(struct extensible *ex)
{
#if HAVE_EXECV
    char            cachefile[STRMAX];
    char            cache[NETSNMP_MAXCACHESIZE];
    ssize_t         cachebytes;
    int             cfd;
#ifdef NETSNMP_EXCACHETIME
    long            curtime;
    static char     lastcmd[STRMAX];
    static int      lastresult;
#endif

    DEBUGMSGTL(("exec:get_exec_output","calling %s\n", ex->command));

    sprintf(cachefile, "%s/%s", get_persistent_directory(), NETSNMP_CACHEFILE);
#ifdef NETSNMP_EXCACHETIME
    curtime = time(NULL);
    if (curtime > (cachetime + NETSNMP_EXCACHETIME) ||
        strcmp(ex->command, lastcmd) != 0) {
        strcpy(lastcmd, ex->command);
        cachetime = curtime;
#endif

        cachebytes = NETSNMP_MAXCACHESIZE;
        ex->result = run_exec_command( ex->command, NULL, cache, &cachebytes );

        unlink(cachefile);
            /*
             * XXX  Use SNMP_FILEMODE_CLOSED instead of 644? 
             */
        if ((cfd = open(cachefile, O_WRONLY | O_TRUNC | O_CREAT, 0644)) < 0) {
                snmp_log(LOG_ERR,"can not create cache file\n");
                setPerrorstatus(cachefile);
                cachetime = 0;
                return -1;
        }
        if (cachebytes > 0)
            write(cfd, (void *) cache, cachebytes);
        close(cfd);
#ifdef NETSNMP_EXCACHETIME
        lastresult = ex->result;
    } else {
        ex->result = lastresult;
    }
#endif
    DEBUGMSGTL(("exec:get_exec_output","using cached value\n"));
    if ((cfd = open(cachefile, O_RDONLY)) < 0) {
        snmp_log(LOG_ERR,"can not open cache file\n");
        setPerrorstatus(cachefile);
        return -1;
    }
    return (cfd);
#else                           /* !HAVE_EXECV */
#if defined(WIN32) && !defined(HAVE_EXECV)
/* MSVC and MinGW.  Cygwin already works as it has execv and fork */
    int         fd;   
    
    /* Reference:  MS tech note: 190351 */
    HANDLE hOutputReadTmp, hOutputRead, hOutputWrite = NULL;
        
    HANDLE hErrorWrite;
    SECURITY_ATTRIBUTES sa;
    PROCESS_INFORMATION pi;
    STARTUPINFO si;
    
    sa.nLength= sizeof(SECURITY_ATTRIBUTES);
    sa.lpSecurityDescriptor = NULL;
    sa.bInheritHandle = TRUE;

    DEBUGMSGTL(("exec:get_exec_output","calling %s\n", ex->command));
    
    /* Child temporary output pipe with Inheritance on (sa.bInheritHandle is true) */    
    if (!CreatePipe(&hOutputReadTmp,&hOutputWrite,&sa,0)) {
      DEBUGMSGTL(("util_funcs", "get_exec_pipes CreatePipe ChildOut: %d\n",
            GetLastError()));
      return -1;
    }
    
    /* Copy the stdout handle to the stderr handle in case the child closes one of 
     * its stdout handles. */
    if (!DuplicateHandle(GetCurrentProcess(),hOutputWrite, GetCurrentProcess(),
          &hErrorWrite,0, TRUE,DUPLICATE_SAME_ACCESS)) {
      DEBUGMSGTL(("util_funcs", "get_exec_output DuplicateHandle: %d\n", GetLastError()));
      return -1;
    }

    /* Create new copies of the input and output handles but set bInheritHandle to 
     * FALSE so the new handle can not be inherited.  Otherwise the handles can not
     * be closed.  */
    if (!DuplicateHandle(GetCurrentProcess(), hOutputReadTmp, GetCurrentProcess(),
          &hOutputRead, 0, FALSE, DUPLICATE_SAME_ACCESS)) {
      DEBUGMSGTL(("util_funcs", "get_exec_output DupliateHandle ChildOut: %d\n", GetLastError()));
      CloseHandle(hErrorWrite);
      return -1;
    }   

    /* Close the temporary output and input handles */
    if (!CloseHandle(hOutputReadTmp)) {
      DEBUGMSGTL(("util_funcs", "get_exec_output CloseHandle (hOutputReadTmp): %d\n", GetLastError()));
      CloseHandle(hErrorWrite);
      CloseHandle(hOutputRead);
      return -1;
    }
    
    /* Associates a C run-time file descriptor with an existing operating-system file handle. */
    fd = _open_osfhandle((long) hOutputRead, 0);
    
    /* Set up STARTUPINFO for CreateProcess with the handles and have it hide the window
     * for the new process. */
    ZeroMemory(&si,sizeof(STARTUPINFO));
    si.cb = sizeof(STARTUPINFO);
    si.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
    si.hStdOutput = hOutputWrite;
    si.hStdError = hErrorWrite;
    si.wShowWindow = SW_HIDE;
   
    /* Launch the process that you want to redirect.  Example snmpd.conf pass_persist:
     * pass_persist    .1.3.6.1.4.1.2021.255  c:/perl/bin/perl c:/temp/pass_persisttest
    */
    if (!CreateProcess(NULL, ex->command, NULL, NULL, TRUE, CREATE_NEW_CONSOLE, NULL, NULL, &si, &pi)) {
      DEBUGMSGTL(("util_funcs","get_exec_output CreateProcess:'%s' %d\n",ex->command, GetLastError()));
      CloseHandle(hErrorWrite);
      CloseHandle(hOutputRead);
      return -1;
    }
    
    /* Set global child process handle */
    ex->pid = (int)pi.hProcess;
    ex->tid = (int)pi.hThread;

    /* Close pipe handles to make sure that no handles to the write end of the
     * output pipe are maintained in this process or else the pipe will
     * not close when the child process exits and any calls to ReadFile 
     * will hang.
     */

    if (!CloseHandle(hOutputWrite)){
      DEBUGMSGTL(("util_funcs","get_exec_output CloseHandle hOutputWrite: %d\n",ex->command, GetLastError()));
      return -1;
    }
    if (!CloseHandle(hErrorWrite)) {
      DEBUGMSGTL(("util_funcs","get_exec_output CloseHandle hErrorWrite: %d\n",ex->command, GetLastError()));
      return -1;
    }
    return fd;