[C++知识库]Linux下用c语言实现一个简单的web服务器

github链接：c语言web服务器
这个服务器程序能够处理简单的GET请求，能够解析类似/%s或/./%s类的url
因为后期解析url时感觉c语言的原生字符串不太方便，所以自己简单封装了一个字符串库。
头文件：mystring.h

#ifndef MYSTRING_H
#define MYSTRING_H

typedef struct
{
	char *data;
	long length;
	long ptr;
} String;

String initString();
void addChar(String *str, char ch);
void addString(String *dec, char *src, long len);
int isEqual(String src, char *dec);
long getStringSize(String str);
void freeString(String str);
char *toCString(String str);

#endif //MY_STRING

对应的mystring.c

#include <stdlib.h>
#include <string.h>
#include "mystring.h"
#include "stringarray.h"

#define STRINGLENGTH 30

String initString()
{
	String string;
	string.length = STRINGLENGTH;
	string.ptr = 0;
	string.data = (char *)malloc(sizeof(char) * string.length);
	return string;
}

void addChar(String *str, char ch)
{
	if (str->ptr >= str->length)
	{
		str->length *= 2;
		str->data = (char *)realloc(str->data, str->length);
	}
	str->data[str->ptr++] = ch;
}

void addString(String *dec, char *src, long len)
{
	while (len--)
	{
		addChar(dec, *src);
		src++;
	}
}

int isEqual(String src, char *dec)
{
	for (long i = 0; i < src.ptr; i++)
	{
		if (src.data[i] != dec[i])
		{
			return 0;
		}
	}
	return 1;
}

long getStringSize(String str)
{
	return str.ptr;
}

void freeString(String str)
{
	free(str.data);
}

char *toCString(String str)
{
	str.data[str.ptr] = 0;
	return str.data;
}

然后封装了对mystring类型的列表操作
头文件stringarray.h

#ifndef STRINGARRAY_H
#define STRINGARRAY_H

#include "mystring.h"

typedef struct
{
	String *data;
	long length;
	long ptr;
} StringArray;

StringArray initArray();
void pushBack(StringArray *array, String str);
long getArraySize(StringArray array);
String getString(StringArray array, long ptr);
StringArray split(String str, const char *pat);
void freeArray(StringArray array);

#endif //STRINGARRAY_H

对应的stringarray.c

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

#define ARRAYLENGTH 30

StringArray initArray()
{
	StringArray array;
	array.length = ARRAYLENGTH;
	array.data = (String *)malloc(sizeof(String) * array.length);
	array.ptr = 0;
	return array;
}

void pushBack(StringArray *array, String str)
{
	if (array->ptr >= array->length)
	{
		array->length *= 2;
		array->data = (String *)realloc(array->data, sizeof(String) * array->length);
	}
	array->data[array->ptr++] = str;
}

long getArraySize(StringArray array)
{
	return array.ptr;
}

String getString(StringArray array, long ptr)
{
	if (array.ptr <= ptr)
	{
		fprintf(stderr, "StringArray out of index\n");
		exit(1);
	}
	return array.data[ptr];
}

StringArray split(String str, const char *pat)
{
	StringArray array = initArray();
	char *temp = str.data;
	char *ptr;
	long p = 0;

	while ((ptr = strstr(temp, pat)) != NULL)
	{
		String x = initString();
		while (temp != ptr)
		{
			addChar(&x, *temp);
			temp++;
			p++;
		}
		temp += strlen(pat);
		p++;
		pushBack(&array, x);
	}
	String x = initString();
	while (p < str.ptr)
	{
		addChar(&x, *temp);
		temp++;
		p++;
	}
	pushBack(&array, x);
	return array;
}

void freeArray(StringArray array)
{
	free(array.data);
}

最后是main.c

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <pthread.h>
#include "mystring.h"
#include "stringarray.h"

int server;

void interrupt(int x) //当输入CTRL-C时关闭服务器
{
	if (x == SIGINT)
	{
		shutdown(server, SHUT_RDWR);
		close(server);
		exit(0);
	}
}

String numToStr(long x) //获得将要传输的文件大小并转为字符串类型，以便于写入到http头中
{
	String ans = initString();
	int ptr = 0;
	int data[1000];
	while (x)
	{
		data[ptr++] = x % 10;
		x /= 10;
	}
	for(ptr--; ptr >= 0; ptr--)
	{
		addChar(&ans, (char) (data[ptr] + 0x30));
	}
	return ans;
}

void sender(int client, char *fileName)
{
	String str = initString();
	FILE *fp = fopen(fileName, "rb");
	if (fp) //如果打开文件成功，发送200文件头，否则说明要传输的文件不存在，发送404文件头和404页面
	{
		printf("200\n", fileName);
		char *t = "HTTP/1.0 200 OK\r\n";
		addString(&str, t, strlen(t));
		addString(&str, "Content-Length: ", 16);
		int x;
		long len = 0;
		String temp = initString();
		while ((x = fgetc(fp)) != EOF) //将文件中读到的字符加到temp中并记录文件大小
		{
			len++;
			addChar(&temp, (char) x);
		}
		String l = numToStr(len); //获得将要传输的文件大小并转为字符串类型，以便于写入到http头中
		addString(&str, toCString(l), getStringSize(l)); //向http头中添加文件大小信息
		addString(&str, "\r\n\r\n", 4);
		addString(&str, toCString(temp), getStringSize(temp)); //将要传输的内容写在http头后面
		freeString(l);
		freeString(temp);
		fclose(fp);
	}
	else
	{
		printf("404\n", fileName);
		addString(&str, "HTTP/1.1 404 Not Found\r\n\r\n", 26);
		fp = fopen("404.html", "rb");
		int x;
		while ((x = fgetc(fp)) != EOF)
		{
			addChar(&str, (char) x);
		}
		fclose(fp);
	}
	write(client, toCString(str), str.ptr);
	freeString(str);
}

void *handle(void *arg) //处理请求
{
	int client = *(int *)arg; //获得客户端socket
	String str = initString();
	char buffer[1024];
	read(client, buffer, sizeof(buffer));
	/* 开始解析url信息
	在这里只解析GET信息
	只判断url为/%s和/./%s时的情况，%s为请求的文件
	*/
	addString(&str, buffer, strlen(buffer));
	StringArray array = split(str, "\r\n"); //将http请求头按行分割
	for (long i = 0; i < getArraySize(array); i++)
	{
		if (strstr(toCString(getString(array, i)), "GET")) //请求GET
		{
			String url = getString(split(getString(array, i), " "), 1); //得到url信息
			StringArray arr = split(url, "/");
			printf("get %s ", toCString(url));
			if (getArraySize(arr) == 2) //处理url为/%s的情况
			{
				String fileName = getString(arr, 1);
				sender(client, toCString(fileName));
				freeString(fileName);
			}
			else if (getArraySize(arr) == 3 && isEqual(getString(arr, 1), ".")) //处理url为/./%s的情况
			{
				String fileName = getString(arr, 2);
				sender(client, toCString(fileName));
				freeString(fileName);
			}
			freeString(url);
			freeArray(arr);
		}
	}
	freeArray(array);
	freeString(str);
	shutdown(client, SHUT_RDWR);
	close(client);
	return NULL;
}

int main()
{
	//服务器地址为127.0.0.1:8080
	char *addr = "127.0.0.1";
	int port = 8080;
	signal(SIGINT, interrupt); //接收CTRL-C信号
	server = socket(AF_INET, SOCK_STREAM, 0);
	struct sockaddr_in serverAddr;
	memset(&serverAddr, 0, sizeof(serverAddr));
	serverAddr.sin_family = AF_INET;
	serverAddr.sin_port = htons(port);
	serverAddr.sin_addr.s_addr = inet_addr(addr);
	int x = bind(server, (struct sockaddr *) &serverAddr, sizeof(serverAddr));
	if (x != -1)
	{
		printf("Listen at %s:%d\n", addr, port);
		listen(server, 1000);
		struct sockaddr_in clientAddr;
		socklen_t len = sizeof(clientAddr);
		while (1)
		{
			int client = accept(server, (struct sockaddr *) &clientAddr, &len);
			printf("connected by %s\n", inet_ntoa(clientAddr.sin_addr)); //打印客户端连接
			/* 多线程处理 */
			pthread_t th;
			pthread_create(&th, NULL, handle, &client);
		}
	}
	else
	{
		printf("%s:%d cannot be used\n", addr, port);
	}
	close(server);
	return 0;
}