[参考译文] TM4C129XNCZAD：如何检测网络上的 IP 冲突

您好！

 我认为 NDK 中没有内置 API 或方法来检测 IP 冲突。 您将需要在应用程序中检测冲突。 在一些谷歌搜索后,我认为你在做什么是正确的路径-你的第二种方法 似乎是建议在各种文章。 也许、您可以将方法1和方法2结合在一起。 下面是一些提供有关如何检测 IP 冲突的建议的文章。 您可以自行进行更多搜索。  

https://www.dnsstuff.com/ip-address-conflict#:~:text=The%20best%20way%20to%20avoid,addresses%20from%20your%20core%20devices。

https://documentation.its.umich.edu/node/523

https://www.auvik.com/franklyit/blog/how-to-fix-ip-address-conflicts/

谢谢、Charles

这些文章非常有用、我依赖 TI 堆栈中的这些函数

-  在 NDK 引导期间使用 arp 挂钩的读取 arp 包(仅限)
- conmping 我修改了这个函数 alittle 位,以重构它,并适合我的应用程序

第一个场景是使用网络中已有的 IP 对节点进行静态配置

- NDK 启动任务在本质上会发送一条 ARP 广播消息，在网络上声明自己，因此如果此节点已经存在(冲突)
远程节点使用其 MAC 地址、该地址与当前节点 Mac 不同。因此在引导任务期间、我们会设置 ARP 挂钩并读取接收到的消息、如果我们收到配置为源发送器的 IP、并使用不同的 MAC、被视为冲突、 我们采取了措施、我禁用了堆栈、但是您可以禁用接口并定期对其进行检查

对于这种方法、我使用了代码片段、

LLI_setARPHook(fxnARPCallback); //to set the arp hook before starting (booting) the stack

do
{
    rc= NC_NetStart(hCfgIpAddr,\
    SoAd_vNetworkOpenHook,\
    SoAd_vNetworkCloseHook,\
    SoAd_vNetworkIPAddressChangeHook);
}while(rc> 0);

和钩子本身  

void fxnARPCallback(void* data)
{
    ARPHDR* ARPPacketHDR;
    ARPPacketHDR = (ARPHDR*)( ((INT8U*)data) + 14U);

    if( memcmp((ARPPacketHDR->IPSrc),&(SoAd_objstrDCFGType.objstrIPSettings.u32LocalIP), (INT32U) 4U ) == 0U)
    {
        if( memcmp((ARPPacketHDR->SrcAddr), SoAd_objstrDCFGType.objstrIPSettings.u8MACAdressArray, (INT32U) 6U) != 0U)
        {
            /*conflict is detected */
        }
    }
}

然后通过删除和添加 IP 条目在更改 IP 时进行 DETech 合并，在执行此操作之前，我们需要对这个新的 IP 执行 ping 操作，如果它没有 ping 操作，则 IP 不被使用，如果 ping 操作成功，则我们可以更改我们的 IP 配置。  在运行时使用并回复我并记录检测到 conflcit 的消息   

我的 ping 函数版本如下所示

INT8 SoAd_Ping( IPN *IPAddr, INT8S s8Attempts )
{
    fd_set              ibits;
    INT32S              cc,fromlen;
    UINT16              cnt_send=0, cnt_recv=0;     /* Packets send and received */
    SOCKET              s;                          /* ICMP socket file descriptor */
    struct  sockaddr_in to;                         /* who to ping */
    struct  sockaddr_in from;                       /* who replied */
    static INT8S        pBuf[30] = {0};
    struct  timeval     timeout;                    /* Timeout struct for select */
    INT32U              timestart;

    INT8S               retCode;
    INT8U               SucessAttempts;

    (void)fdOpenSession(TaskSelf());
    retCode = Ping_Success;
    SucessAttempts = 0U;
    /* Create the ICMP Socket */
    s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
    if( s == INVALID_SOCKET )
    {
        SoAd_vmLogError1(&objstrSoAdModuleInfoType, "failed socket create (%d)",fdError());
        retCode = Ping_INVALID_SOCKET;
    }
    /* Create to "to" address */
    bzero( &to, sizeof(struct sockaddr_in));
    to.sin_family       = AF_INET;
    to.sin_addr.s_addr  = *IPAddr;
    /* Create to "from" address */
    bzero( &from, sizeof(struct sockaddr_in));
    from.sin_family     = AF_INET;
    /* Set socket option to allow us to broadcast */
    cc = 1;
    if( setsockopt( s, SOL_SOCKET, SO_BROADCAST, &cc, sizeof(INT32S) ) < 0 )
    {
        SoAd_vmLogError1(&objstrSoAdModuleInfoType, "failed set IP broadcast (%d)",fdError());
        retCode = Ping_Failed_SetIPBroadcast;
    }
    /* Configure our timeout to be 0.5 seconds */
    timeout.tv_sec  = 0;
    timeout.tv_usec = 500000;

    SoAd_vmLogActivity5(&objstrSoAdModuleInfoType, "Pinging %d.%d.%d.%d with %d data bytes",\
                        (INT32U)(*IPAddr & 0xFFU),\
                        (INT32U)((*IPAddr >> 8)&0xFFU),\
                        (INT32U)((*IPAddr >> 16)&0xFFU),\
                        (INT32U)((*IPAddr >> 24)&0xFFU),\
                        PING_DATALEN );
    /* Ping loop */
    while( cnt_send < s8Attempts )
    {
        /* Use send count for sequence - starts at "1" */
        cnt_send++;
        memset(pBuf, 0x00, sizeof(char)*40);
        /* Build the ping packet */
        SoAd_BuildPing( pBuf, cnt_send );
        /* Get the time now */
        timestart = llTimerGetTime(0);
        cnt_recv = 0;
        /* Send the ping */
        cc = sendto( s, pBuf, PING_DATALEN, 0,(struct sockaddr *)&to, sizeof(to) );
        if( cc < 0 )
        {
            SoAd_vmLogError1(&objstrSoAdModuleInfoType, "failed sento (%d)",fdError());
        }
        else if( cc != PING_DATALEN )
        {
            SoAd_vmLogError0(&objstrSoAdModuleInfoType, "sento - partial write!");
        }
        else{
            while( (timestart+2) > llTimerGetTime(0) )
            {
                /* Select for timeout period second */
                FD_ZERO(&ibits);
                FD_SET(s, &ibits);
                if( fdSelect( (INT32S)s, &ibits, 0, 0, &timeout ) < 0 )
                {
                    SoAd_vmLogError1(&objstrSoAdModuleInfoType, "failed select (%d)",fdError());
                    retCode = Ping_Failed_SelectSocket;
                    break;
                }
                /* Check for a reply */
                if( FD_ISSET(s, &ibits) )
                {
                    fromlen = sizeof(from);
                    cc = (INT32S)recvfrom( s, pBuf, PING_DATALEN, 0,(struct sockaddr *)&from, &fromlen );
                    if( cc < 0 )
                    {
                        SoAd_vmLogError1(&objstrSoAdModuleInfoType, "failed recvfrom (%d)",fdError());
                        retCode = Ping_Failed_recvfrom;
                        break;
                    }
                    /* Check the reply. Bump the recv count if good reply */
                    if( SoAd_CheckPing( pBuf, cnt_send, cc, IPAddr) )
                    {
                        SucessAttempts++;
                        cnt_recv++;
                        break;
                    }
                }
            }
            /* If send is more than reply, then we missed a reply */
            if( !cnt_recv )
            {
                SoAd_vmLogError0(&objstrSoAdModuleInfoType, "Reply timeout");
                retCode = Ping_Reply_Timeout;
            }
        }
    }

    if(retCode == Ping_Success && SucessAttempts > s8Attempts/2)
    {
        retCode = Ping_Success;
    }
    else
    {
        /*do nothing*/
        retCode = Ping_Fail;
    }

    if( s != INVALID_SOCKET )
        fdClose( s );

    return retCode;
}

static INT8 SoAd_CheckPing( INT8S *ps8Buf,INT16U u16Seq,INT32S s32NumberOfBytes, IPN* ps8IpStr)
{
    INT32S     ICMPLen;
    INT16U     Id,Seq;
    INT8U      retCode;

    retCode = Ping_SUCCESS_ECHOREPLY;
    /* Get header pointers */

    /* Get the total length of the ICMP message */
    ICMPLen = (uint)(HNC16( ((IPHDR *)ps8Buf)->TotalLen )) - ( (((IPHDR *)ps8Buf)->VerLen & 0xF) * 4 );

    /* Verify the ICMP type */
    if( ((ICMPHDR *)(ps8Buf+( (((IPHDR *)ps8Buf)->VerLen & 0xF) * 4 )))->Type != ICMP_ECHOREPLY )
        retCode = Ping_NOTICMP_ECHOREPLY ;

    /* Get the seq and the id */
    Seq = (INT32S)HNC16(((ICMPREQHDR *)((ICMPHDR *)(ps8Buf+( (((IPHDR *)ps8Buf)->VerLen & 0xF) * 4 )))->Data)->Seq);
    Id  = (INT32S)HNC16(((ICMPREQHDR *)((ICMPHDR *)(ps8Buf+( (((IPHDR *)ps8Buf)->VerLen & 0xF) * 4 )))->Data)->Id);

    /* If the reply is incorrect, don't continue */
    if( Id != PING_IDENTIFICATION || Seq != u16Seq )
    {
        SoAd_vmLogError4(&objstrSoAdModuleInfoType, "Non-matching echo reply from %d.%d.%d.%d", \
                         (INT32U)(*ps8IpStr & 0xFFU),\
                         (INT32U)((*ps8IpStr >> 8)&0xFFU),\
                         (INT32U)((*ps8IpStr >> 16)&0xFFU),\
                         (INT32U)((*ps8IpStr >> 24)&0xFFU));
        retCode = Ping_NonMatching_ECHOREPLY;
    }

    /* Print out data on correct reply */
    SoAd_vmLogActivity7(&objstrSoAdModuleInfoType, "Reply from %d.%d.%d.%d, with %d bytes, Seq=%u, TTL = %d", \
                        (INT32U)(*ps8IpStr & 0xFFU),\
                        (INT32U)((*ps8IpStr >> 8)&0xFFU),\
                        (INT32U)((*ps8IpStr >> 16)&0xFFU),\
                        (INT32U)((*ps8IpStr >> 24)&0xFFU),\
                        ICMPLen-8,\
                        Seq,\
                        ((IPHDR *)ps8Buf)->Ttl);

    /* Validate the data payload */
    if( ICMPLen != PING_DATALEN )
    {
        SoAd_vmLogError2(&objstrSoAdModuleInfoType, "Data length error in reply (%d of %d)", s32NumberOfBytes, PING_DATALEN);
        retCode = Ping_DataLenError_ECHOREPLY;
    }


    if( *(UINT8 *)((ps8Buf+( (((IPHDR *)ps8Buf)->VerLen & 0xF) * 4 )+8)) != (UINT8)('0'+8) )
    {
        SoAd_vmLogError3(&objstrSoAdModuleInfoType, "Data verification error in reply (%d 0x%x 0x%x)", \
                         s32NumberOfBytes, \
                         *(UINT8 *)((ps8Buf+( (((IPHDR *)ps8Buf)->VerLen & 0xF) * 4 )+s32NumberOfBytes)), \
                         '0'+s32NumberOfBytes );
        retCode = Ping_DataVerFailed_ECHOREPLY;
    }
    return retCode;
}

static void SoAd_BuildPing( INT8S *ps8Buf, INT16U u16seq )
{
    *(ps8Buf+8) = '0'+8;
    /* Get pointers to the ICMP and ICMPREQ headers */

    /* Fill out echo request */
    ((ICMPHDR *)ps8Buf)->Type   = ICMP_ECHO;
    ((ICMPHDR *)ps8Buf)->Code   = 0;
    ((ICMPREQHDR *)(((ICMPHDR *)ps8Buf)->Data))->Id    = HNC16(PING_IDENTIFICATION);
    ((ICMPREQHDR *)(((ICMPHDR *)ps8Buf)->Data))->Seq   = HNC16(u16seq);

    /* Checksum the ICMP header */
    /* Although the checksum function is reentrant, we follow the rules */
    /* and call llEnter()/llExit() since this is a stack function. */
    llEnter();
    ICMPChecksum( (ICMPHDR *)ps8Buf, PING_DATALEN );
    llExit();
}