tcp拥塞控制算法代码

以下是TCP Reno算法的简单实现代码：

#include <stdio.h>
#include <stdlib.h>

#define MAX_PACKETS 1000 // 最大数据包数量
#define MSS 512 // 最大段大小
#define RTT 200 // 往返时间
#define ALPHA 0.125 // 慢启动下降因子
#define BETA 0.25 // 拥塞避免下降因子
#define THRESHOLD 16 // 拥塞阈值

// TCP Reno算法状态
typedef enum {
    SLOW_START,
    CONGESTION_AVOIDANCE,
    FAST_RECOVERY
} TCP_Reno_State;

// 数据包结构体
typedef struct {
    int seq_num; // 序列号
    int size; // 数据包大小
} Packet;

// 计算超时时间
int timeout() {
    return 2 * RTT;
}

// 慢启动算法
int slow_start(int cwnd, int ssthresh) {
    cwnd += MSS;
    if (cwnd >= ssthresh) {
        return CONGESTION_AVOIDANCE;
    }
    return SLOW_START;
}

// 拥塞避免算法
int congestion_avoidance(int cwnd, int ssthresh) {
    cwnd += MSS * (MSS / cwnd);
    if (cwnd >= ssthresh) {
        return CONGESTION_AVOIDANCE;
    }
    return SLOW_START;
}

// 快速恢复算法
int fast_recovery(int cwnd, int ssthresh) {
    cwnd = ssthresh;
    return CONGESTION_AVOIDANCE;
}

// TCP Reno算法
int tcp_reno(Packet packets[], int num_packets) {
    int cwnd = MSS;
    int ssthresh = THRESHOLD * MSS;
    int state = SLOW_START;
    int acked = 0;
    int dup_ack_count = 0;
    int i;

    for (i = 0; i < num_packets; i++) {
        // 接收到确认号
        if (packets[i].seq_num <= acked) {
            continue;
        }
        acked = packets[i].seq_num;

        // 慢启动状态下
        if (state == SLOW_START) {
            state = slow_start(cwnd, ssthresh);
        }
        // 拥塞避免状态下
        else if (state == CONGESTION_AVOIDANCE) {
            state = congestion_avoidance(cwnd, ssthresh);
        }
        // 快速恢复状态下
        else if (state == FAST_RECOVERY) {
            cwnd += MSS;
            state = CONGESTION_AVOIDANCE;
        }

        // 重传数据包
        if (dup_ack_count >= 3) {
            ssthresh = cwnd / 2;
            cwnd = ssthresh + 3 * MSS;
            state = FAST_RECOVERY;
            dup_ack_count = 0;
            continue;
        }

        // 发送数据包
        while (cwnd >= packets[i].size) {
            cwnd -= packets[i].size;
        }

        // 接收到重复确认号
        if (packets[i].seq_num == acked) {
            dup_ack_count++;
            continue;
        }

        // 更新拥塞窗口大小
        if (state == SLOW_START) {
            cwnd += MSS;
        } else if (state == CONGESTION_AVOIDANCE) {
            cwnd += MSS * (MSS / cwnd);
        }
    }

    return 0;
}

// 主函数
int main() {
    Packet packets[MAX_PACKETS];
    int num_packets;
    int i;
    for (i = 0; i < num_packets; i++) {
        packets[i].seq_num = i;
        packets[i].size = MSS;
    }
    tcp_reno(packets, num_packets);
    return 0;
}