TCP simultaneous open测试

源代码

/*************************************************************************> File Name: common.h> Author: hsz> Brief:> Created Time: 2024年10月23日 星期三 09时47分51秒************************************************************************/#pragma once#include <stdio.h>
#include <string.h>
#include <errno.h>#include <memory>#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>struct PeerMessage
{uint16_t    is_server;char        host[32];uint16_t    port;
};auto size = sizeof(PeerMessage);bool ReusePortAddr(int32_t sock, int32_t reuse = 1)
{if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, (char*)&reuse, sizeof(reuse))) {perror("setsockopt(SO_REUSEPORT) error");return false;}if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char*)&reuse, sizeof(reuse))) {perror("setsockopt(SO_REUSEPORT) error");return false;}return true;
}bool TimeoutConnect(int32_t sockfd, sockaddr_in addr, uint32_t timeoutMS)
{int flags = fcntl(sockfd, F_GETFL, 0);if (fcntl(sockfd, F_SETFL, flags | O_NONBLOCK) < 0) {perror("fcntl error");}std::shared_ptr<void>(nullptr, [&](void *) {// 恢复套接字为阻塞模式fcntl(sockfd, F_SETFL, flags);});// 连接到目标地址int ret = connect(sockfd, (struct sockaddr*)&addr, sizeof(addr));if (ret < 0 && errno != EINPROGRESS) { // 连接失败且不是EINPROGRESS// EINPROGRESS 表示仍在进行连接printf("Failed to connect: [%d:%s]\n", errno, strerror(errno));return false;}// 在非阻塞模式下，需要使用 select() 或 epoll() 等函数来等待连接完成fd_set fdset;FD_ZERO(&fdset);FD_SET(sockfd, &fdset);struct timeval timeout;timeout.tv_sec = 1;timeout.tv_usec = 0;ret = select(sockfd + 1, nullptr, &fdset, nullptr, &timeout);if (ret < 0) {printf("Failed to select: [%d:%s]\n", errno, strerror(errno));return false;} else if (ret == 0) { // 超时了printf("Connection timed out\n");return false;} else {  // 连接成功或失败int valopt = -1;socklen_t optlen = sizeof(valopt);getsockopt(sockfd, SOL_SOCKET, SO_ERROR, (void*)&valopt, &optlen);  // 获取连接结果if (valopt != 0) {  // 连接失败printf("Failed to connect: [%d:%s]\n", valopt, strerror(valopt));return false;}}return true;
}

/*************************************************************************> File Name: tcp_simultaneous_open.cc> Author: hsz> Brief:> Created Time: 2024年10月25日 星期五 15时35分09秒************************************************************************/#include <iostream>
#include <string>
#include <cstring>
#include <thread>
#include <map>
#include <vector>
#include <thread>
#include <functional>#include <getopt.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <unistd.h>#include "common.h"#include <log/log.h>#define LOG_TAG "TCP simultaneous open"int32_t Bind(const char *local_host, uint16_t local_port)
{// 创建套接字int sockfd = socket(AF_INET, SOCK_STREAM, 0);if (sockfd < 0) {printf("socket error, errno: %d, errstr: %s\n", errno, strerror(errno));return -1;}int32_t flag = 1;if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEPORT, (char*)&flag, sizeof(flag))) {perror("setsockopt(SO_REUSEPORT) error");close(sockfd);return -1;}sockaddr_in local_addr;memset(&local_addr, 0, sizeof(local_addr));local_addr.sin_family = AF_INET;local_addr.sin_addr.s_addr = inet_addr(local_host);local_addr.sin_port = htons(local_port);if (bind(sockfd, (struct sockaddr*)&local_addr, sizeof(local_addr)) < 0) {perror("bind error");close(sockfd);return -1;}return sockfd;
}void thread_func(int32_t sock, const char *peer_host, uint16_t peer_port)
{sockaddr_in remote_addr;memset(&remote_addr, 0, sizeof(remote_addr));remote_addr.sin_family = AF_INET;remote_addr.sin_addr.s_addr = inet_addr(peer_host);remote_addr.sin_port = htons(peer_port);if (peer_port == 12999) {usleep(10); // usleep(1000 * 1000);}LOGI("begin");if (TimeoutConnect(sock, remote_addr, 1000)) {send(sock, "hello", 6, 0);char buf[16] = { '\0' };recv(sock, buf, sizeof(buf), 0);LOGI("recv: %s", buf);}LOGI("end");
}int main(int argc, char **argv)
{const char *bind_host = "192.168.3.10";int32_t firstSock = Bind(bind_host, 12999);int32_t secondSock = Bind(bind_host, 13999);if (firstSock < 0 || secondSock < 0) {return 0;}std::thread th1(std::bind(&thread_func, firstSock, bind_host, 13999));std::thread th2(std::bind(&thread_func, secondSock, bind_host, 12999));th1.join();th2.join();return 0;
}

测试结果

概率正常连接
抓包结果

延迟测试

由于两个套接字是客户端性质，必须保证同时处于SYN-SENT状态。
流程梳理：客户端A （127.0.0.1:12999）、客户端B（127.0.0.1:13999）
1、A向B发送SYN，此时B必须处于SYN-SENT状态，否则就会因为是客户端性质而收到RST信号
2、A收到RST信号后进入CLOSED 状态，此时B在延迟1ms后发送SYN，将同样收到RST信号