UDP服务器/客户端代码示例

UDP服务器代码：

#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    if (argc != 3)
    {
        cout << "usage: " << argv[0] << " ip port" << endl;
        return -1;
    }

    char *szIp = argv[1];
    in_addr_t iIp = inet_addr(szIp);
    if (iIp == INADDR_NONE)
    {
        cerr << "fail to parse ip: " << szIp << endl;
        return -1;
    }
    char *pEnd = NULL;
    uint16_t usPort = strtoul(argv[2], &pEnd, 10);
    if (*pEnd != '')
    {
        cerr << "fail to parse port: " << argv[2] << endl;
        return -1;
    }

    int iSockFd = socket(AF_INET, SOCK_DGRAM, 0);
    if (iSockFd < 0)
    {
        cerr << "fail to create socket, err: " << strerror(errno) << endl;
        return -1;
    }
    cout << "create socket fd " << iSockFd << endl;

    sockaddr_in oAddr;
    memset(&oAddr, 0, sizeof(oAddr));
    oAddr.sin_family = AF_INET;
    oAddr.sin_addr.s_addr = iIp;
    oAddr.sin_port = htons(usPort);
    if (bind(iSockFd, (sockaddr *)&oAddr, sizeof(oAddr)) < 0)
    {
        cerr << "fail to bind addr " << szIp << ":" << usPort << ", err: " << strerror(errno) << endl;
        return -1;
    }
    cout << "bind addr " << szIp << ":" >> usPort << endl;

    uint8_t acRecvBuf[64 * 1024];
    while (true)
    {
        sockaddr_in oClientAddr;
        socklen_t iAddrLen = sizeof(oClientAddr);
        ssize_t iRecvLen = recvfrom(iSockFd, acRecvBuf, sizeof(acRecvBuf), 0, (sockaddr *)&oClientAddr, &iAddrLen);
        if (iRecvLen < 0)
        {
            cerr << "fail to recv, err: " << strerror(errno) << endl;
            continue;
        }
        cout << "recv data from " << inet_ntoa(oClientAddr.sin_addr) << ":" << ntohs(oClientAddr.sin_port) << ", len: " << iRecvLen << endl;

        ssize_t iSendLen = sendto(iSockFd, acRecvBuf, iRecvLen, 0, (sockaddr *)&oClientAddr, iAddrLen);
        if (iSendLen < 0)
        {
            cerr << "fail to send, err: " << strerror(errno) << endl;
            continue;
        }
        cout << "echo to client, len: " << iSendLen << endl;
    }

    return 0;
}

UDP客户端代码：

#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    if (argc != 4)
    {
        cout << "usage: " << argv[0] << " ip port message" << endl;
        return -1;
    }

    char *szIp = argv[1];
    in_addr_t iIp = inet_addr(szIp);
    if (iIp == INADDR_NONE)
    {
        cerr << "fail to parse ip: " << szIp << endl;
        return -1;
    }
    char *pEnd = NULL;
    uint16_t usPort = strtoul(argv[2], &pEnd, 10);
    if (*pEnd != '')
    {
        cerr << "fail to parse port: " << argv[2] << endl;
        return -1;
    }
    char *szMsg = argv[3];
    size_t uiMsgLen = strlen(szMsg);

    int iSockFd = socket(AF_INET, SOCK_DGRAM, 0);
    if (iSockFd < 0)
    {
        cerr << "fail to create socket, err: " << strerror(errno) << endl;
        return -1;
    }
    cout << "create socket fd " << iSockFd << endl;

    sockaddr_in oServerAddr;
    memset(&oServerAddr, 0, sizeof(oServerAddr));
    oServerAddr.sin_family = AF_INET;
    oServerAddr.sin_addr.s_addr = iIp;
    oServerAddr.sin_port = htons(usPort);
    ssize_t iSendLen = sendto(iSockFd, szMsg, uiMsgLen, 0, (sockaddr *)&oServerAddr, sizeof(oServerAddr));
    if (iSendLen < 0)
    {
        cerr << "fail to send, err: " << strerror(errno) << endl;
        return -1;
    }
    cout << "send to " << szIp <<  ":" << usPort << ", len: " << uiMsgLen << ", msg: " << szMsg << endl;

    char szRecvBuf[64 * 1024];
    sockaddr_in oRecvAddr;
    socklen_t iAddrLen = sizeof(oRecvAddr);
    ssize_t iRecvLen = recvfrom(iSockFd, szRecvBuf, sizeof(szRecvBuf), 0, (sockaddr *)&oRecvAddr, &iAddrLen);
    if (iRecvLen < 0)
    {
        cerr << "fail to recv, err: " << strerror(errno) << endl;
        return -1;
    }
    szRecvBuf[iRecvLen] = '';
    cout << "recv from " << inet_ntoa(oRecvAddr.sin_addr) << ":" << ntohs(oRecvAddr.sin_port) << ", len: " << iRecvLen << ", msg: " << szRecvBuf << endl; 

    return 0;
}