windows网络编程-2015.12.29

在windows环境下，使用netstat命令查看网络状态，具体命令如下所示：

netstat -ano | findstr listenport

在windows环境下，创建udp程序接收端，具体代码如下：

// Command line options:
//    udp_server [-i:IP] [-p:port]
//           -i:IP    Local IP address to listen on
//           -p:int   Local port

#include <string>
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib, "ws2_32.lib")

const int DEFAULT_BUFFER_LENGTH = 4096;

void Usage()
{
    printf("usage: udp_server [-i:IP] [-p:port]
");
    printf("       -i:IP    Local IP address to listen on
");
    printf("       -p:int   Local port
");
    ExitProcess(1);
}

struct AddrInfo
{
    std::string ip;
    int port;
};

AddrInfo GetInputAddrInfo(int argc, char **argv)
{
    if(argc < 3)
    {
        Usage();
    }

    AddrInfo addrInfo;
    for(int i = 1; i < argc; i++)
    {
        if ((argv[i][0] == '-'))
        {
            switch (tolower(argv[i][1]))
            {
            case 'p':   //port
                if (strlen(argv[i]) > 3)
                {
                    addrInfo.port = atoi(&argv[i][3]);
                }
                break;
            case 'i':    //ip
                if (strlen(argv[i]) > 3)
                {
                    addrInfo.ip = std::string(&argv[i][3]);
                }
                break;
            default:
                Usage();
                break;
            }
        }
    }
    return addrInfo;
}

int main(int argc, char **argv)
{
    AddrInfo addrInfo = GetInputAddrInfo(argc, argv);

    WSADATA wsd;
    if (WSAStartup(MAKEWORD(1,1), &wsd) != 0)
    {
        printf("WSAStartup failed!
");
        return 1;
    }

    SOCKET s;
    if( (s = socket(AF_INET, SOCK_DGRAM, 0)) == INVALID_SOCKET)
    {
        printf("socket() failed; %d
", WSAGetLastError());
        return 1;
    }

    SOCKADDR_IN local;
    local.sin_family = AF_INET;
    local.sin_port = htons((short)addrInfo.port);
    local.sin_addr.s_addr = inet_addr(addrInfo.ip.c_str());

    if (bind(s, (SOCKADDR *)&local, sizeof(local)) == SOCKET_ERROR)
    {
        printf("bind() failed: %d
", WSAGetLastError());
        return 1;
    }

    char* recvBuf = (char*)malloc(DEFAULT_BUFFER_LENGTH);
    if (recvBuf == NULL)
    {
        printf("GlobalAlloc() failed: %d
", GetLastError());
        return 1;
    }

    SOCKADDR_IN sender;

    while(true)
    {
        int sendSize = sizeof(SOCKADDR_IN);
        int ret = recvfrom(s, recvBuf, DEFAULT_BUFFER_LENGTH, 0, (SOCKADDR *)&sender, &sendSize);
        if (ret == SOCKET_ERROR)
        {
            printf("recvfrom() failed; %d
", WSAGetLastError());
            break;
        }
        else if (ret == 0)
        {
            break;
        }
        else
        {
            recvBuf[ret] = '';
            printf("[%s] send me [%s]
", inet_ntoa(sender.sin_addr), recvBuf);
        }
    }

    closesocket(s);
    free(recvBuf);
    WSACleanup();
    return 0;
}

运行上述程序，使用命令netstat -ano | findstr 8888，获得如下输出结果：

按照相同步骤，创建udp程序发送端，具体代码如下：

// Command line options:
//    udp_client [-r:IP] [-p:port]
//           -r:IP    Recipient's IP address
//           -p:int   Remote port
//           -n:x     Number of times to send message

#include <string>
#include <winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib, "ws2_32.lib")

const char SEND_MESSAGE[] = "Hello world!";

void Usage()
{
    printf("usage: udp_client [-r:IP] [-p:port] [-n:x]
");
    printf("       -r:IP    Recipient's IP address
");
    printf("       -p:int   Remote port
");
    printf("       -n:x     Number of times to send message");
    ExitProcess(1);
}

struct InputInfo
{
    std::string ip;
    int port;
    int sendTimes;
};

InputInfo GetInputInfo(int argc, char **argv)
{
    if(argc < 4)
    {
        Usage();
    }

    InputInfo inputInfo;
    for(int i = 1; i < argc; i++)
    {
        if ((argv[i][0] == '-'))
        {
            switch (tolower(argv[i][1]))
            {
            case 'p':   //port
                if (strlen(argv[i]) > 3)
                {
                    inputInfo.port = atoi(&argv[i][3]);
                }
                break;
            case 'r':    //ip
                if (strlen(argv[i]) > 3)
                {
                    inputInfo.ip = std::string(&argv[i][3]);
                }
                break;
            case 'n':   //Number of times to send message
                if (strlen(argv[i]) > 3)
                {
                    inputInfo.sendTimes = atol(&argv[i][3]);
                }
                break;
            default:
                Usage();
                break;
            }
        }
    }

    return inputInfo;
}

int main(int argc, char **argv)
{
    InputInfo inputInfo = GetInputInfo(argc, argv);

    WSADATA wsd;
    if (WSAStartup(MAKEWORD(1,1), &wsd) != 0)
    {
        printf("WSAStartup failed!
");
        return 1;
    }

    SOCKET s;
    if( (s = socket(AF_INET, SOCK_DGRAM, 0)) == INVALID_SOCKET)
    {
        printf("socket() failed; %d
", WSAGetLastError());
        return 1;
    }

    SOCKADDR_IN recipient;
    recipient.sin_family = AF_INET;
    recipient.sin_port = htons((short)inputInfo.port);
    recipient.sin_addr.s_addr = inet_addr(inputInfo.ip.c_str());

    for(int i = 0; i < inputInfo.sendTimes; ++i)
    {
        int ret = sendto(s, SEND_MESSAGE, strlen(SEND_MESSAGE), 0, (SOCKADDR*)&recipient, sizeof(recipient));
        if(ret == SOCKET_ERROR)
        {
            printf("sendto() failed, %d
", WSAGetLastError());
            break;
        }
        else if(ret == 0)
        {
            break;
        }        
        else
        {
            printf("send [%s] to [%s]
", std::string(SEND_MESSAGE, ret).c_str(), inet_ntoa(recipient.sin_addr));
        }
    }

    closesocket(s);
    WSACleanup();
    return 0;
}