实现滑动窗口协议仿真的C++源代码

以下是一个简单的滑动窗口协议仿真的C++源代码示例：

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <vector>

using namespace std;

// 定义数据包结构体
struct Packet {
    int seq; // 数据序号
    int len; // 数据长度
    string data; // 数据内容
};

// 定义发送方和接收方窗口大小
const int WINDOW_SIZE = 8;

// 定义发送方和接收方窗口内的数据包信息
vector<Packet> sendWindow;
vector<bool> sendAcked;
vector<Packet> recvWindow;
vector<bool> recvAcked;

// 定义超时时间和重传次数
const int TIMEOUT = 1000; // 超时时间为1s
const int MAX_RESEND = 3; // 最多重传3次

// 模拟网络延时和丢包
void simulateDelay() {
    srand(time(NULL));
    int delay = rand() % 500; // 延时0-500ms
    int loss = rand() % 100; // 丢包率0-100%
    if (loss < 5) { // 丢包率为5%
        cout << "Packet lost!" << endl;
        exit(0);
    }
    else {
        cout << "Delay " << delay << "ms" << endl;
        clock_t start_time = clock();
        while (clock() - start_time < delay) {}
    }
}

// 发送数据包
void sendPacket(Packet packet) {
    sendWindow.push_back(packet);
    sendAcked.push_back(false);
    simulateDelay();
    cout << "Packet " << packet.seq << " sent" << endl;
}

// 发送确认消息
void sendAck(int seq) {
    simulateDelay();
    cout << "Ack " << seq << " sent" << endl;
}

// 发送方的逻辑
void sender() {
    int nextSeqNum = 0;
    int base = 0;
    int resendCount = 0;

    // 发送窗口向前移动
    for (int i = base; i < base + WINDOW_SIZE && i < sendWindow.size(); i++) {
        if (!sendAcked[i]) {
            sendPacket(sendWindow[i]);
        }
        else {
            cout << "Packet " << sendWindow[i].seq << " already acked" << endl;
        }
    }

    // 接收确认消息
    while (true) {
        if (base == sendWindow.size()) { // 所有数据包都已发送并确认
            cout << "All packets sent and acked" << endl;
            break;
        }
        if (resendCount == MAX_RESEND) { // 超过最大重传次数
            cout << "Resend count exceeded, transmission failed" << endl;
            break;
        }
        // 检查是否有超时未确认的数据包
        for (int i = base; i < base + WINDOW_SIZE && i < sendWindow.size(); i++) {
            if (!sendAcked[i] && clock() - sendWindow[i].seq > TIMEOUT) {
                resendCount++;
                sendPacket(sendWindow[i]);
            }
        }
        // 接收确认消息
        int ackSeq;
        cout << "Waiting for ack..." << endl;
        cin >> ackSeq;
        for (int i = base; i < base + WINDOW_SIZE && i < sendWindow.size(); i++) {
            if (!sendAcked[i] && sendWindow[i].seq == ackSeq) {
                sendAcked[i] = true;
            }
        }
        // 移动发送窗口
        while (sendAcked[base] && base < sendWindow.size()) {
            base++;
        }
        for (int i = base; i < base + WINDOW_SIZE && i < sendWindow.size(); i++) {
            if (!sendAcked[i]) {
                sendPacket(sendWindow[i]);
            }
        }
    }
}

// 接收方的逻辑
void receiver() {
    int expectedSeqNum = 0;
    int base = 0;

    // 接收窗口向前移动
    for (int i = base; i < base + WINDOW_SIZE && i < recvWindow.size(); i++) {
        if (!recvAcked[i] && recvWindow[i].seq == expectedSeqNum) {
            sendAck(recvWindow[i].seq);
            recvAcked[i] = true;
            expectedSeqNum++;
        }
    }

    // 接收数据包并发送确认消息
    while (true) {
        // 接收数据包
        Packet packet;
        cout << "Waiting for packet..." << endl;
        cin >> packet.seq >> packet.len >> packet.data;
        if (packet.seq < expectedSeqNum) { // 已经接收过的数据包
            cout << "Packet " << packet.seq << " already received" << endl;
            sendAck(packet.seq);
        }
        else if (packet.seq >= expectedSeqNum + WINDOW_SIZE) { // 窗口外的数据包
            cout << "Packet " << packet.seq << " out of window" << endl;
            sendAck(expectedSeqNum - 1);
        }
        else { // 窗口内的未接收数据包
            recvWindow.push_back(packet);
            recvAcked.push_back(false);
            // 移动接收窗口
            while (recvAcked[base] && base < recvWindow.size()) {
                base++;
            }
            for (int i = base; i < base + WINDOW_SIZE && i < recvWindow.size(); i++) {
                if (!recvAcked[i] && recvWindow[i].seq == expectedSeqNum) {
                    sendAck(recvWindow[i].seq);
                    recvAcked[i] = true;
                    expectedSeqNum++;
                }
            }
        }
        if (base == recvWindow.size()) { // 所有数据包都已接收并确认
            cout << "All packets received and acked" << endl;
            break;
        }
    }
}

int main() {
    int choice;
    cout << "Choose mode: 1 for sender, 2 for receiver" << endl;
    cin >> choice;
    if (choice == 1) {
        sender();
    }
    else if (choice == 2) {
        receiver();
    }
    else {
        cout << "Invalid choice" << endl;
    }
    return 0;
}

这个示例实现了一个简单的滑动窗口协议仿真，其中包括发送方和接收方的逻辑。在实际应用中，还需要考虑更多的细节和错误处理。