标题: 在CE 4.2上实现ping功能

CE 4.2不支持raw socket，因此移植BSD Socket、Winsock的ping实现到PDA上，这个
想法趁早放弃吧。我最初也是不信邪的，其实这种不信邪完全没道理，仅仅是个人发
傻。

进MSDN里搜了一番，发现CE 4.2虽然不支持raw socket，但直接提供了一批用于实现
ping的函数。我最终实践成功的方案如下:

#include <icmpapi.h>

#pragma comment( lib, "iphlpapi.lib" )

/*
 * 发送ICMP Echo Request报文，等待ICMP Echo Reply报文。
 *
 * CE不支持raw socket，被迫使用IcmpCreateFile()这类函数。
 */
static void ping
(
    unsigned int        ip,
    FILE               *o,
    unsigned char      *str
)
{
    HANDLE              icmphandle  = INVALID_HANDLE_VALUE;
    unsigned char      *buf         = NULL;
    unsigned int        buflen;
    /*
     * 取自Windows平台的ping实现
     */
    unsigned char       icmpdata[]  =
    {
    0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
    0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70,
    0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x61,
    0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69
    };
    DWORD               n;

    buflen  = sizeof( ICMP_ECHO_REPLY ) + sizeof( icmpdata );
    buf     = ( unsigned char * )Calloc( buflen, 1 );
    if ( INVALID_HANDLE_VALUE == ( icmphandle = IcmpCreateFile() ) )
    {
        PrintWin32ErrorCLI( "IcmpCreateFile() failed", GetLastError() );
        goto ping_exit;
    }
    /*
     * 发送请求报文
     */
    n       = IcmpSendEcho
    (
        icmphandle,
        ip,
        &icmpdata,
        sizeof( icmpdata ),
        NULL,
        buf,
        buflen,
        timeout * 1000
    );
    if ( 0 == n )
    {
#if 0
        fprintf
        (
            stderr,
            "ip              = 0x%08X\n",
            ip
        );
        PrintWin32ErrorCLI( "IcmpSendEcho() failed", GetLastError() );
#endif
        goto ping_exit;
    }
    if ( debug )
    {
        fprintf
        (
            stderr,
            "n               = %u\n",
            n
        );
        outputBinary
        (
            stderr,
            buf,
            buflen
        );
    }
    if
    (
        ( 1 == n )  &&
        ( ( ( ICMP_ECHO_REPLY * )buf )->Address == ip )
    )
    {
        fprintf
        (
            o,
            "%s\n",
            str
        );
    }

ping_exit:

    if ( INVALID_HANDLE_VALUE != icmphandle )
    {
        IcmpCloseHandle( icmphandle );
        icmphandle  = INVALID_HANDLE_VALUE;
    }
    if ( NULL != buf )
    {
        free( buf );
        buf         = NULL;
    }
    return;
}  /* end of ping */