tango-tsg-master/src/tsg_tamper.cpp

#include <stdio.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "tsg_entry.h"
#include <MESA/MESA_handle_logger.h>
#include "tsg_protocol_common.h"

#define MTU_LEN 65535
#define MAC_LEN 6
#define MAC_LEN_2  ((MAC_LEN)+(MAC_LEN))
#define ETH_IP_TYPE_LEN 2
#define ETH_LEN ((MAC_LEN_2)+(ETH_IP_TYPE_LEN))

#define IPV4_TYPE   1 //ADDR_TYPE_IPV4 ==1 , 取的enum 0x0800
#define IPV6_TYPE   2 //ADDR_TYPE_IPV6 ==2 0x86dd   
#define TCP_TYPE 0x06
#define UDP_TYPE 0x11

#define IPV4_LEN                    20    //ip_len(20) 
#define IPV4_PROTOCOL_INDEX         9     //ipv4_protocol_index_len
#define IPV4_TCP_HEAD_LEN_INDEX     32    //ip_len(20) + tcp_head_len_index()
#define ETH_IPV4_IP_UPD_LEN         28    //ip_len(20) + udp_len(8) 
#define IPV4_IP_LEN_INDEX   2             //ip_len_index(2)

#define IPV6_PROTOCOL_INDEX         6    //ipv6_protocol_index(6)
#define IPV6_LEN        40
#define ETH_IPV6_LEN                40    //ipv6_len(40)
#define IPV6_TCP_OPTION_LEN_INDEX   52    //ipv6_len(40) + tcp_head_len_index(12)
#define IPV6_UDP_PALYLOAD_START_INDEX 48  //ipv6_len(40) + udp_len(8)
#define IPV6_IP_PAYLOAD_INDEX  4         //ipv6_payload_index(4)


int tamper_calc(const struct streaminfo *a_stream, char *str, int endlen)
{
    int i = 0;
    int j = 0;
    char temp;
    int startlen = 0;
    int data_len = a_stream->ptcpdetail->datalen;   //tcp和udp结构体内容一样，取tcp的datalen即可


    //判断是否需要偏移一个字节
    if(data_len%2!=0){
         startlen = 1;     
    }

    //最小交换paythod的第2个字节和第四个字节，否则不处理
    if ((endlen - startlen) < 4){
        return 0;
    }

    //start_len+1 : 因为计算校验和是16bit为单位，这里调换16bit的低8bit。
    for(i=startlen+1; i<endlen; i=i+2){
        for (j=i+2; j<endlen; j=j+2){
            if(str[i] != str[j]){
                temp = str[i];
                str[i] = str[j];
                str[j] = temp;
                return i;
            }
        }
    }
    return 0;
}

unsigned char send_tamper_xxx(const struct streaminfo *a_stream, const void *raw_pkt)
{
    const char *p_trans_payload = NULL;
    int trans_layload_len = 0;
    char tamper_buf[MTU_LEN] = {0}; 
    int  ret = 0;
    
    if(a_stream==NULL){
        return STATE_GIVEME;   
    }

    p_trans_payload = (char *)a_stream->ptcpdetail->pdata;
    trans_layload_len = a_stream->ptcpdetail->datalen;
    if((p_trans_payload==NULL)||(trans_layload_len<=0)){
        return STATE_GIVEME;   
    }

    memcpy(tamper_buf, p_trans_payload, trans_layload_len);
    ret = tamper_calc(a_stream, tamper_buf, trans_layload_len);
    MESA_handle_runtime_log(g_tsg_para.logger,
            RLOG_LV_DEBUG,
            __FUNCTION__,
            "Modify the index position of the payload: %d",
            ret);
    if(ret > 0){
        ret=tsg_send_inject_packet(a_stream, SIO_DEFAULT, tamper_buf, trans_layload_len, a_stream->routedir); 
        if(ret == 0){
            return STATE_DROPPKT;
        }
    }

    return STATE_GIVEME;   
}