windows下用UDP 广播在特定网卡上发包

背景

https://www.jianshu.com/p/a3692e86cb1e

总结

通过路由表来达到在指定网卡上发包的效果。

解决方案

  1. 更改路由表
    使用python的pysnmp库更方便
    这里给出的是windows自带的dos命令
route change 255.255.255.255 mask 255.255.255.255 192.168.1.101 metric 230 if 22

其中 192.168.1.101 是你本机的IP地址
metric 230 是你决定的metric值，比其他的小就行
if 22 是无线网络接口编号，也是通过route print命令看出来的


  1. 得到无线网卡信息之后，在特定网络广播（192.168.1.255）而不使用255.255.255.255
    main.c
#include<stdio.h>
#include<WinSock2.h>

#include "GetNICMsg.h"
void raise_message(char *msg);
char * changeIPaddrtoBroadcastIPaddr(char *ipaddr, char *netmask);

#pragma comment(lib,"ws2_32.lib")
#pragma warning(disable:4996)
#define RECV_PORT 2019
#define SEND_PORT 2019
#define MAXBUFLEN 1024
#define DONTPRINTIT 0
#define PRINTIT 1

#define FIRST_USING_WIRELESS_NIC 0

int main()
{
    WSADATA wsa;
    WSAStartup(0x201, &wsa);

    SOCKET sock_host;
    sock_host = socket(AF_INET, SOCK_DGRAM, 0);
    BOOL bBoardcast = TRUE;
    if (SOCKET_ERROR == setsockopt(sock_host, SOL_SOCKET, SO_BROADCAST, (char*)&bBoardcast, sizeof(bBoardcast)))
    {
        printf("setsockopt failed with error code: %d/n", WSAGetLastError());
        return -1;
    }

    char *ipaddr = NULL, *netmask = NULL,*ip_broadcast;
    
    if (getAllAdapterInfo(&ipaddr, &netmask, MIB_IF_TYPE_WiFi, DONTPRINTIT, FIRST_USING_WIRELESS_NIC)!= 0)
    {
        raise_message("找不到一个可用的无线网卡\n");
        closesocket(sock_host);
        return -1;
    }

        // 获得无线网卡的广播地址
    ip_broadcast = changeIPaddrtoBroadcastIPaddr(ipaddr, netmask);


    sockaddr_in addr_local, addr_remote;
    addr_remote.sin_addr.S_un.S_addr = inet_addr(ip_broadcast);
    addr_remote.sin_port = htons(SEND_PORT);
    addr_remote.sin_family = AF_INET;


    int retval, headlen = sizeof(addr_remote);
    char buf[MAXBUFLEN] = "hello???";
    
    
    
    int ID_list_temp[5] = { htons(1), htons(2), htons(4), htons(8), htons(16) };
    while (1)
    {
        for (int i = 0; i < 5; ++i)
        {
            retval = sendto(sock_host, (char *)(ID_list_temp + i), sizeof(int), 0, (sockaddr *)&addr_remote, headlen);
            if (retval < 0)
            {
                retval = WSAGetLastError();
                return -1;
            }
        }


    }

    return 0;

}

void raise_message(char *msg)
{
    printf(msg);
}

char * changeIPaddrtoBroadcastIPaddr(char *ipaddr,char *netmask)
{
    unsigned long int ipaddr_int = inet_addr(ipaddr);
    unsigned long int netmask_int = inet_addr(netmask);
    unsigned long int netmask_low = inet_addr("255.255.255.255");
    netmask_low = netmask_low^netmask_int;
    ipaddr_int = ipaddr_int | netmask_low;
    char *ipbroadcast;
    in_addr ipaddr_in;
    ipaddr_in.S_un.S_addr = ipaddr_int;
    ipbroadcast = inet_ntoa(ipaddr_in);
    return ipbroadcast;

}

GetNICMsg.cpp

#include "GetNICMsg.h"

void GetMsgfromcur(char** ipaddr, char **netmask,PIP_ADAPTER_INFO cur, bool printit)
{
    IP_ADDR_STRING *pIpAddrString = &(cur->IpAddressList);
    if (printit)
    {
        
        cout << "IP:" << pIpAddrString->IpAddress.String << endl;
        cout << "子网掩码:" << pIpAddrString->IpMask.String << endl;
        cout << "Context:" << pIpAddrString->Context << endl;

        char hex[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

        // mac 地址一般6个字节 
        // mac 二进制转16进制字符串
        char macStr[18] = { 0 };//12+5+1
        int k = 0;
        for (int j = 0; j < cur->AddressLength; j++){

            macStr[k++] = hex[(cur->Address[j] & 0xf0) >> 4];
            macStr[k++] = hex[cur->Address[j] & 0x0f];
            macStr[k++] = '-';
        }
        macStr[k - 1] = 0;

        cout << "MAC:" << macStr << endl; // mac地址 16进制字符串表示 
        cout << "--------------------------------------------------" << endl;

    }
    *ipaddr = (char *)malloc(sizeof(IP_ADDRESS_STRING));
    strcpy(*ipaddr, pIpAddrString->IpAddress.String);
    *netmask = (char *)malloc(sizeof(IP_ADDRESS_STRING));
    strcpy(*netmask, pIpAddrString->IpMask.String);
    

}

int getAllAdapterInfo(char** ipaddr, char **netmask, int NICtype, bool printit, int sequence)
{
    if (sequence == 0)
        sequence = 1;
    int CurrentSequence = 1;

    //char *ipaddr = (char *)malloc(sizeof(IP_ADDRESS_STRING));


    PIP_ADAPTER_INFO pIpAdapterInfo = new IP_ADAPTER_INFO[ADAPTERNUM];// 20个网卡空间 足够了 
    unsigned long stSize = sizeof(IP_ADAPTER_INFO) * ADAPTERNUM;
    // 获取所有网卡信息，参数二为输入输出参数 
    int nRel = GetAdaptersInfo(pIpAdapterInfo, &stSize);
    // 空间不足
    if (ERROR_BUFFER_OVERFLOW == nRel) {
        // 释放空间
        if (pIpAdapterInfo != NULL)
            delete[] pIpAdapterInfo;
        return -1;
    }

    PIP_ADAPTER_INFO cur = pIpAdapterInfo;
    // 多个网卡 通过链表形式链接起来的 
    while (cur){
        
        if (cur->Type == NICtype)
        {
            switch (cur->Type) {
            case MIB_IF_TYPE_OTHER:
                break;
            case MIB_IF_TYPE_ETHERNET:
                GetMsgfromcur(ipaddr, netmask,cur, printit);
                if (strcmp(UeslessIPaddr, *ipaddr) != 0)
                {
                    if (CurrentSequence == sequence)
                        return 0;
                    else
                        ++CurrentSequence;
                }

                break;
            case MIB_IF_TYPE_TOKENRING:
                break;
            case MIB_IF_TYPE_FDDI:
                break;
            case MIB_IF_TYPE_PPP:
                break;
            case MIB_IF_TYPE_LOOPBACK:
                break;
            case MIB_IF_TYPE_SLIP:
                break;
            case MIB_IF_TYPE_WiFi:
                GetMsgfromcur(ipaddr, netmask, cur, printit);
                
                if (strcmp(UeslessIPaddr, *ipaddr) != 0)
                {
                    if (CurrentSequence == sequence)
                        return 0;
                    else
                        ++CurrentSequence;
                }

                break;
            default://无线网卡,Unknown type

                break;
            }
        }


        cur = cur->Next;
        
    }

    // 释放空间
    if (pIpAdapterInfo != NULL)
        delete[] pIpAdapterInfo;
}

void getAllAdapterInfo()
{

    PIP_ADAPTER_INFO pIpAdapterInfo = new IP_ADAPTER_INFO[ADAPTERNUM];// 20个网卡空间 足够了 
    unsigned long stSize = sizeof(IP_ADAPTER_INFO) * ADAPTERNUM;
    // 获取所有网卡信息，参数二为输入输出参数 
    int nRel = GetAdaptersInfo(pIpAdapterInfo, &stSize);
    // 空间不足
    if (ERROR_BUFFER_OVERFLOW == nRel) {
        // 释放空间
        if (pIpAdapterInfo != NULL)
            delete[] pIpAdapterInfo;
        return;
    }

    PIP_ADAPTER_INFO cur = pIpAdapterInfo;
    // 多个网卡 通过链表形式链接起来的 
    while (cur){
        cout << "网卡描述：" << cur->Description << endl;
        switch (cur->Type) {
        case MIB_IF_TYPE_OTHER:
            break;
        case MIB_IF_TYPE_ETHERNET:
        {
            IP_ADDR_STRING *pIpAddrString = &(cur->IpAddressList);
            cout << "IP:" << pIpAddrString->IpAddress.String << endl;
            cout << "子网掩码:" << pIpAddrString->IpMask.String << endl;
            cout << "Context:" << pIpAddrString->Context << endl;
        }
            break;
        case MIB_IF_TYPE_TOKENRING:
            break;
        case MIB_IF_TYPE_FDDI:
            break;
        case MIB_IF_TYPE_PPP:
            break;
        case MIB_IF_TYPE_LOOPBACK:
            break;
        case MIB_IF_TYPE_SLIP:
            break;

        default://无线网卡,Unknown type
        {
            IP_ADDR_STRING *pIpAddrString = &(cur->IpAddressList);
            cout << "IP:" << pIpAddrString->IpAddress.String << endl;
            cout << "子网掩码:" << pIpAddrString->IpMask.String << endl;

        }
            break;
        }
        char hex[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

        // mac 地址一般6个字节 
        // mac 二进制转16进制字符串
        char macStr[18] = { 0 };//12+5+1
        int k = 0;
        for (int j = 0; j < cur->AddressLength; j++){

            macStr[k++] = hex[(cur->Address[j] & 0xf0) >> 4];
            macStr[k++] = hex[cur->Address[j] & 0x0f];
            macStr[k++] = '-';
        }
        macStr[k - 1] = 0;

        cout << "MAC:" << macStr << endl; // mac地址 16进制字符串表示 
        cur = cur->Next;
        cout << "--------------------------------------------------" << endl;
    }

    // 释放空间
    if (pIpAdapterInfo != NULL)
        delete[] pIpAdapterInfo;
}

GetNICMsg.h

#ifndef __GETNICMSG__
#define __GETNICMSG__

#include <iostream>
#include <vector>
#include <WinSock2.h>
#include <Iphlpapi.h>
#pragma comment(lib,"Iphlpapi.lib") 
#pragma comment(lib,"ws2_32.lib")
#pragma warning(disable:4996)
using namespace std;



#define ADAPTERNUM 20
#define MIB_IF_TYPE_WiFi 71
#define UeslessIPaddr "0.0.0.0"
int getAllAdapterInfo(char** ipaddr, char **netmask, int NICtype, bool printit, int sequence);
void getAllAdapterInfo();
void GetMsgfromcur(char** ipaddr, char **netmask, PIP_ADAPTER_INFO cur, bool printit);
#endif
  1. 通过setsockopt函数确定在哪个网卡上发送
    在windows下不可行，但是在Linux下可以通过setsockopt(..., SOL_SOCKET, SO_BINDTODEVICE, "ethX")完成。
    参考https://stackoverflow.com/questions/683624/udp-broadcast-on-all-interfaces
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