web服务器

首先创建几个函数以方便我们调用

open_clinetfd: 创建一个网络socket，作为客户端，并且尝试连接主机
open_listenfd: 创建socket，作为主机，并开始监听

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#include "mynet.h"

int open_clientfd(char *hostname, char *port){
	int clientfd;
	struct addrinfo hints, *listp, *p;

	memset(&hints, 0,sizeof(struct addrinfo));
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_NUMERICSERV;
	hints.ai_flags |= AI_ADDRCONFIG;
	getaddrinfo(hostname, port, &hints, &listp);
	for(p=listp;p;p=p->ai_next){
		if((clientfd = socket(p->ai_family, p->ai_socktype,p->ai_protocol))<0)
		  continue;
		if(connect(clientfd,p->ai_addr,p->ai_addrlen)!=-1)
		  break;
		close(clientfd);
	}

	freeaddrinfo(listp);
	if(!p) return -1;
	else return clientfd;
}
int open_listenfd(char *port)
{
	struct addrinfo hints, *listp, *p;
	int listenfd, optval=1;
	memset(&hints, 0 ,sizeof(struct addrinfo));
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG;
	hints.ai_flags |= AI_NUMERICSERV;
	getaddrinfo(NULL, port, &hints, &listp);

	for(p=listp;p;p=p->ai_next){
		if((listenfd = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) < 0)
		  continue;
		setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,(const void *)&optval,sizeof(int));

		if(bind(listenfd,p->ai_addr,p->ai_addrlen)==0)
		  break; //success
		close(listenfd); //bind fail, try next
	}

	freeaddrinfo(listp);
	if(!p)
	  return -1;
	if(listen(listenfd,LISTENQ)<0){
		close(listenfd);
		return -1;
	}
	return listenfd;
}

我们的服务器有以下几个模块

int main(int argc, char** argv)：从shell读取参数作为端口，使用上述open_listenfd创建一个监听端口，使用accept创建一个连接，进入do_it开始处理事务
void doit(int fd)：do_it的参数是connfd，读取请求，调用parse_uri分析请求是静态请求还是动态请求，分别调用serve_static和serve_dynamic进行响应
int parse_uri(char *uri, char *filename, char *cgiargs)：url不包含cgi-bin则认为是静态请求，读取请求的文件，若没有，默认返回home.html；否则认为是动态请求
void serve_static(int fd, char *filename, int filesize)：发送header，再发送文件
void serve_dynamic(int fd, char *filename, char *cgiargs)：服务动态内容，在cgi-bin找运行程序

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#include "mynet.h"

void doit(int fd);
void read_requesthdrs(int fd);
int parse_uri(char *uri, char *filename, char *cgiargs);
void serve_static(int fd, char *filename, int filesize);
void get_filetype(char *filename, char *filetype);
void serve_dynamic(int fd, char *filename, char *cgiargs);
void clienterror(int fd, char*cause, char *errnum, char *shortmsg, char *longmsg);

int main(int argc, char** argv)
{
	int listenfd,connfd;
	char hostname[MAXLINE], port[MAXLINE];
	socklen_t clientlen;
	struct sockaddr_storage clientaddr;

	if(argc!=2){
		fprintf(stderr, "usage: %s <port>\n",argv[0]);
		exit(1);
	}

	listenfd = open_listenfd(argv[1]);
	while(1){
		clientlen = sizeof(clientaddr);
		connfd = accept(listenfd,(SA*)&clientaddr,&clientlen);
		getnameinfo((SA*)&clientaddr,clientlen,hostname,MAXLINE,port,MAXLINE,0);
		printf("Accepted connection from (%s, %s)\n",hostname,port);
		doit(connfd);
		close(connfd);
	}
}


void doit(int fd){
	int is_static;
	struct stat sbuf;
	char buf[MAXLINE], method[MAXLINE], uri[MAXLINE], version[MAXLINE];
	char filename[MAXLINE], cgiargs[MAXLINE];

	read(fd, buf, MAXLINE);
	printf("Requset hears:\n");
	printf("%s",buf);
	sscanf(buf, "%s %s %s", method, uri, version);
	if(strcasecmp(method, "GET")){
		clienterror(fd, method, "501", "Not implementedd","Tiny does not implement this method");
		return;
	}
	//read_requesthdrs(fd);
	is_static = parse_uri(uri,filename,cgiargs);
	if(stat(filename,&sbuf)<0){
		clienterror(fd, filename, "404", "Not found", "Tiny couldn't find this file");
		return;
	}

	if(is_static){
		if(!(S_ISREG(sbuf.st_mode)) || !(S_IRUSR & sbuf.st_mode)){
			clienterror(fd, filename, "403", "Forbidden", "Tiny couldn't read the file");
			return;
		}
		serve_static(fd,filename,sbuf.st_size);
	}
	else {
		if(!(S_ISREG(sbuf.st_mode)) || !(S_IXUSR & sbuf.st_mode)){
			clienterror(fd, filename, "403", "Forbidden", "Tiny couldn't run the CGI program");
			return;
		}
		serve_dynamic(fd,filename,cgiargs);
	}
}

void read_requesthdrs(int fd){
	char buf[MAXLINE];

	read(fd,buf,MAXLINE);
	while(strcmp(buf, "\r\n")){
		read(fd,buf,MAXLINE);
		printf("%s",buf);
	}
	return;
}
int parse_uri(char *uri, char *filename, char *cgiargs){
	char *ptr;

	if(!strstr(uri, "cgi-bin")) {
		strcpy(cgiargs,"");
		strcpy(filename,".");
		strcat(filename,uri);
		if(uri[strlen(uri)-1] == '/')
		  strcat(filename,"home.html");
		return 1;
	}
	else{	//dynammic content
		ptr = index(uri,'?');
		if (ptr) {
			strcpy(cgiargs, ptr+1);
			*ptr = '\0';
		}
		else
		  strcpy(cgiargs, ptr+1);
		strcpy(filename,".");
		strcat(filename,uri);
		return 0;
	}
}


void serve_static(int fd, char *filename, int filesize){
	int srcfd;
	char *srcp, filetype[MAXLINE], buf[MAXLINE*10];

	get_filetype(filename, filetype);
	sprintf(buf, "HTTP/1.0 200 OK\r\n");
	sprintf(buf, "%sServer: Tiny Web Server\r\n",buf);
	sprintf(buf, "%sConnection: close\r\n",buf);
	sprintf(buf, "%sContent-length: %d\r\n",buf,filesize);
	sprintf(buf, "%sContent-type: %s\r\n\r\n",buf,filetype);
	write(fd,buf,strlen(buf));
	printf("Response headers:\n");
	printf("%s",buf);

	srcfd = open(filename,O_RDONLY, 0);
	srcp = mmap(0, filesize, PROT_READ, MAP_PRIVATE, srcfd, 0);
	close(srcfd);
	write(fd,srcp,filesize);
	munmap(srcp,filesize);
}

void get_filetype(char *filename, char *filetype){
	 if(strstr(filename,".html"))
	   strcpy(filetype, "text/html");
	 else if (strstr(filename,".gif"))
	   strcpy(filetype, "image/gif");
	else if (strstr(filename,".png"))
	   strcpy(filetype, "image/png");
	else if (strstr(filename,".jpg"))
	   strcpy(filetype, "image/jpeg");
	else
	   strcpy(filetype, "image/plain");
}

void serve_dynamic(int fd, char *filename, char *cgiargs){
	char buf[MAXLINE],*emptylist[] = {NULL};

	sprintf(buf,"HTTP/1.0 200 OK\r\n");
	write(fd,buf,strlen(buf));
	sprintf(buf,"Server: Tiny Web Server\r\n");
	write(fd,buf,strlen(buf));

	if(fork()==0) {
		setenv("QUERY_STRING",cgiargs,1);
		dup2(fd,STDOUT_FILENO);
		execve(filename,emptylist,environ);
	}
	wait(NULL);
}

void clienterror(int fd, char*cause, char *errnum, char *shortmsg, char *longmsg){
	char buf[MAXLINE], body[100*MAXLINE];
	sprintf(body,"<html><title>Tiny Error</title>");
	sprintf(body,"%s<body bgcolor=""ffffff"">\r\n",body);
	sprintf(body,"%s%s: %s\r\n",body,errnum,shortmsg);
	sprintf(body,"%s<p>%s: %s\r\n",body,longmsg,cause);
	sprintf(body,"%s<hr><em>The Tiny Web server</em>\r\n",body);

	sprintf(buf, "HTTP/1.0 %s %s\r\n",errnum,shortmsg);
	write(fd,buf,strlen(buf));
	sprintf(buf, "Content-type: text/html\r\n");
	write(fd,buf,strlen(buf));
	sprintf(buf, "Content-length: %d\r\n\r\n",(int)strlen(body));
	write(fd,buf,strlen(buf));
	write(fd,body,strlen(body));
}

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