WinSock2 实现简单服务器

不管用啥语言写，原理都是差不多的，用Server Socket持续监听某个端口，每次accept到一个请求，就对这个Client Socket的发送的内容进行接收、分析，再发送给客户端一些信息。

// ConsoleApplication4.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#ifndef _MSC_VER
#define _WIN32_WINNT 0x0501
#endif
#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <Windows.h>

#ifdef _MSC_VER
#pragma warning(disable: 4996)
#endif

#define BUFSIZE 1024

#pragma comment(lib, "Ws2_32.lib")

typedef struct
{
	char* name;
	char* value;
} Header;

typedef struct
{
	char* protocol;
	char* statusCode;
	int headersSize;
	Header* headers;
	char* body;
} HttpResponseMessage;

void send_http_response_message(SOCKET socket, HttpResponseMessage httpResponseMessage);

int main()
{
	int result = 0;
	WSADATA wsaData;
	SOCKET netSocket;

	struct addrinfo* resultAddrInfo = NULL;
	struct addrinfo hintsAddrInfo;

	result = WSAStartup(MAKEWORD(2, 2), &wsaData);

	if (result)
	{
		printf("Error code %d\n", result);
		return 0;
	}

	ZeroMemory(&hintsAddrInfo, sizeof(hintsAddrInfo));
	hintsAddrInfo.ai_family = AF_INET;
	hintsAddrInfo.ai_socktype = SOCK_STREAM;
	hintsAddrInfo.ai_protocol = IPPROTO_TCP;
	hintsAddrInfo.ai_flags = AI_PASSIVE;
	getaddrinfo(NULL, "6680", &hintsAddrInfo, &resultAddrInfo);

	netSocket = socket(
		resultAddrInfo->ai_family,
		resultAddrInfo->ai_socktype,
		resultAddrInfo->ai_protocol
	);

	if (netSocket == INVALID_SOCKET)
	{
		printf("invalid socket\n");
		return 0;
	}

	result = bind(
		netSocket,
		resultAddrInfo->ai_addr,
		(int)resultAddrInfo->ai_addrlen
	);

	if (result == SOCKET_ERROR)
	{
		printf("bind failed\n");
		return 0;
	}

	result = listen(netSocket, SOMAXCONN);

	if (result == SOCKET_ERROR)
	{
		printf("listen failed\n");
		return 0;
	}

	printf("Open http://localhost:6680/\n");

	while (1)
	{
		SOCKET clientSocket = accept(netSocket, NULL, NULL);

		if (clientSocket == INVALID_SOCKET) continue;

		printf("receive a client\n");

		HttpResponseMessage hrm;

		hrm.protocol = "HTTP/1.1";
		hrm.statusCode = "200 OK";
		Header* headers = (Header*)malloc(sizeof(Header) * 1);

		if (headers != NULL)
		{
			headers[0].name = (char*)malloc(sizeof(char) * 20);
			if (headers[0].name != NULL)
				strcpy(headers[0].name, "Content-Type");

			headers[0].value = (char*)malloc(sizeof(char) * 20);
			if (headers[0].value != NULL)
				strcpy(headers[0].value, "text/html");

		}

		hrm.headers = headers;
		hrm.headersSize = 1;
		hrm.body = (char*)malloc(sizeof(char) * 1024);

		if (hrm.body != NULL)
			strcpy(
				hrm.body,
				"#<span style=\"color:blue;\">include</span> &lt;stdio.h&gt;<br /><br />"
				"<span style=\"color:red;\">int</span> main() {<br />"
				"&emsp;<span style=\"color: #ffa500;\">printf</span>(<span style=\"color: green;\">\"Hello World!\"</span>);<br />"
				"}"
				"<script>alert('Welcome to SIPC115!');</script>"
			);

		send_http_response_message(clientSocket, hrm);

		printf("send message finished\n");
		closesocket(clientSocket);
	}
}


void send_http_response_message(
	const SOCKET socket,
	const HttpResponseMessage httpResponseMessage
)
{
	char contentLength[33];

	send(socket, httpResponseMessage.protocol, strlen(httpResponseMessage.protocol), 0);
	send(socket, " ", 1, 0);
	send(socket, httpResponseMessage.statusCode, strlen(httpResponseMessage.statusCode), 0);
	send(socket, "\n", 1, 0);

	send(
		socket,
		"Content-Length: ",
		16,
		0
	);

	itoa(strlen(httpResponseMessage.body), contentLength, 10);

	send(
		socket,
		contentLength,
		strlen(contentLength),
		0
	);

	send(
		socket,
		"\n",
		1,
		0
	);

	for (int i = 0; i < httpResponseMessage.headersSize; i++)
	{
		send(
			socket,
			httpResponseMessage.headers[i].name,
			strlen(httpResponseMessage.headers[i].name),
			0
		);
		send(socket, ": ", 2, 0);
		send(
			socket,
			httpResponseMessage.headers[i].value,
			strlen(httpResponseMessage.headers[i].value),
			0
		);
		send(socket, "\n", 1, 0);
	}
	send(socket, "\n", 1, 0);
	send(socket, httpResponseMessage.body, strlen(httpResponseMessage.body), 0);
}

上面没有写接收内容的功能，不过不难，差不多就是下面的样子：

#define BUFSIZE 1024

// ......

char recvBuf[BUFSIZE];
int result = 0;
// ......

while ((result = recv(clientSocket, recvBuf, BUFSIZE, 0)) > 0)
{
	content = content.append(recvBuf);
	printf("%d, ", result);
	if (result < BUFSIZE) break;
}

//......

result表示每次接收到的字节数，接收状态下，result大于0，并小于等于缓冲区大小，即BUFSIZE。

当然，最好不要直接使用std::string的append，可能会出现乱码等情况。

先写这么多。