TCP/IP编程——recv/send与缓冲区大小实验

最新推荐文章于 2024-09-15 17:00:00 发布

kuizhao8951

最新推荐文章于 2024-09-15 17:00:00 发布

阅读量2.3k

点赞数 1

CC 4.0 BY-SA版权

分类专栏： TCPIP

本文链接：https://blog.youkuaiyun.com/kuizhao8951/article/details/89363932

TCPIP 专栏收录该内容

13 篇文章

订阅专栏

本文探讨了tcpsend函数的发送长度限制，实验证明其最大长度可超过65535字节，但受收端缓存大小影响。通过实验一和实验二的代码示例，详细展示了在不同缓存条件下，发送与接收数据的行为。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

tcp send函数发送的最大长度可以超过65535字节吗？

能的

但是要注意

发端的字节全部都会发出去，但是收端的缓存如果不够，并不会继续覆盖

测试代码如下：

实验一

客户端（发端）

#include <Winsock2.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib,"ws2_32.lib")
int main()
{
	SOCKET clientsocket;
	SOCKADDR_IN serveraddr;
	char buf[1024];

	WSADATA wsa;
	WSAStartup(MAKEWORD(2, 0), &wsa);	//初始化WS2_32.DLL

	//创建套接字
	if ((clientsocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) <= 0)
	{
		printf("套接字socket创建失败!\n");
		return -1;
	}

	serveraddr.sin_family = AF_INET;
	serveraddr.sin_port = htons(5060);
	serveraddr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");

	//请求连接
	printf("尝试连接中...\n");
	if (connect(clientsocket, (SOCKADDR *)&serveraddr, sizeof(serveraddr)) != 0)
	{
		printf("连接失败!\n");
		return -1;
	}
	printf("连接成功!\n");

	unsigned int total = 0;
	while (1)
	{
		char szSendBuf[10] = {0,1,2,3,4,5,6,7,8,9};
		int iRet = send(clientsocket, szSendBuf, sizeof(szSendBuf), 0);
		total += iRet;
		printf("%d\n", iRet);
		printf("iRet is %u, total %u\n", iRet, total);
		getchar();
	}
	closesocket(clientsocket);
	WSACleanup();    //释放WS2_32.DLL
	system("PAUSE ");
	return 0;
}

服务器（收端）

#include <Winsock2.h>
#include <stdio.h>
#pragma comment(lib,"ws2_32.lib")
int main()
{
	SOCKET serversoc;
	SOCKET clientsoc;
	SOCKADDR_IN serveraddr;
	SOCKADDR_IN clientaddr;
	char buf[1024];
	int len;

	WSADATA wsa;
	WSAStartup(MAKEWORD(2, 0), &wsa);	//初始化WS2_32.DLL

	//创建套接字
	if ((serversoc = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) <= 0)
	{
		printf("套接字socket创建失败!\n");
		return -1;
	}

	//命名协议，IP，端口
	serveraddr.sin_family = AF_INET;
	serveraddr.sin_port = htons(5060);
	serveraddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);

	//绑定套接字
	if (bind(serversoc, (SOCKADDR *)&serveraddr, sizeof(serveraddr)) != 0)
	{
		printf("套接字绑定失败!\n");
		return -1;
	}

	printf("开始监听...\n");
	//监听请求
	if (listen(serversoc, 1) != 0)
	{
		printf("监听失败!\n");
		return -1;
	}

	len = sizeof(SOCKADDR_IN);

	//接收请求
	if ((clientsoc = accept(serversoc, (SOCKADDR *)&clientaddr, &len)) <= 0)
	{
		printf("接受连接失败!\n");
		return -1;
	}
	printf("连接成功\n");
	//test TCP是否能大数据发送
	char szRecvBuf[3] = { 0,0,0 };
	int iRet = recv(clientsoc, szRecvBuf, sizeof(szRecvBuf), 0);
	printf("recv size is %d, iRet is %d\n", sizeof(szRecvBuf), iRet);
	for (int i = 0; i < 3; i++){
		printf("%d", szRecvBuf[i]);
	}
	getchar();
	WSACleanup();     //释放WS2_32.DLL
	system("PAUSE ");
	return 0;
}

结果：

实验二

收端S
	char szRecvBuf[BUFFLEN] = { 0 };
	int iRet = recv(clientsoc, szRecvBuf, sizeof(szRecvBuf), 0);
	printf("recv size is %d, iRet is %d\n", sizeof(szRecvBuf), iRet);
	for (int i = 0; i < BUFFLEN; i++){
		printf("%d", szRecvBuf[i]);
	}
	getchar();
发端C
	char szSendBuf[65535 * 10] = { 0 };
	for (int i = 0; i < 65535; i++){
		for (int j = 0; j < 10; j++){
			szSendBuf[i * 10 + j] = j;
		}
	}
	while (1)
	{
		int iRet = send(clientsocket, szSendBuf, sizeof(szSendBuf), 0);
		total += iRet;
		printf("%d\n", iRet);
		printf("iRet is %u, total %u\n", iRet, total);

		getchar();
	}

结果：

收端
#define BUFFLEN 65535

	char szRecvBuf[BUFFLEN] = { 0 };
	int iRet = recv(clientsoc, szRecvBuf, sizeof(szRecvBuf), 0);
	printf("recv size is %d, iRet is %d\n", sizeof(szRecvBuf), iRet);
	for (int i = 0; i < BUFFLEN; i++){
		printf("%d", szRecvBuf[i]);
	}
	getchar();
发端如上