linux如何分析获取到的网卡数据包

[mznxbc123456]

我socket先绑定本地网卡，然后recvfrom(fd, g_acRecvBuf, g_iRecvBufSize, 0, NULL, &stFromLen);
然后这个g_acRecvBuf我定义
struct ether_header *pstEthHead = NULL;
struct ip *pstIpHead = NULL;
能Ethnet帧头解析和ip数据包解析
struct ether_header *pstEthHead = NULL;
struct ip *pstIpHead = NULL;
//以太网数据,ip数据,TCP首部,应用数据,以太网尾部
//Ethnet帧头解析
pstEthHead = (struct ether_header*)pcFrameData;
iRet = parseEthHead(pstEthHead);
if (0 > iRet){
return iRet;
}
//IP数据包类型
pstIpHead = (struct ip *)(pstEthHead + 1);
iRet = parseIpHead(pstIpHead);
这样只是能获取到eth协议，接收发送的mac地址以及ip协议和接收发送的ip，我无法获取到数据，%S都是乱码。
我想获取http的url信息，我怎么打印这个g_acRecvBuf里的数据信息呢

[mznxbc123456]

1111111111111SIZE=54,MESSAGE= SMAC=[00:0c:29:6d:a8:89] DMAC=[00:50:56:f9:e6:de] IP-Type:6(tcp) 我%s打印出g_acRecvBuf基本都是空，但是有大小是recvfrom的返回值是54

[赵4老师]

仅供参考：

void HexDump(char *buf,int len,int addr) {
    int i,j,k;
    char binstr[80];

    for (i=0;i<len;i++) {
        if (0==(i%16)) {
            sprintf(binstr,"%08x -",i+addr);
            sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
        } else if (15==(i%16)) {
            sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
            sprintf(binstr,"%s  ",binstr);
            for (j=i-15;j<=i;j++) {
                sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
            }
            printf("%s\n",binstr);
        } else {
            sprintf(binstr,"%s %02x",binstr,(unsigned char)buf[i]);
        }
    }
    if (0!=(i%16)) {
        k=16-(i%16);
        for (j=0;j<k;j++) {
            sprintf(binstr,"%s   ",binstr);
        }
        sprintf(binstr,"%s  ",binstr);
        k=16-k;
        for (j=i-k;j<i;j++) {
            sprintf(binstr,"%s%c",binstr,('!'<buf[j]&&buf[j]<='~')?buf[j]:'.');
        }
        printf("%s\n",binstr);
    }
}

[mznxbc123456]

我已经知道怎么获取信息了，ip下面还有一层tcp，跳过tcp就能进入数据区，这样就能打印出数据啦