web服务器实现

最近工作中需要客户端和服务器使用https协议进行通信，我负责客户端程序的编写，想到以前在深入理解操作系统中看过web服务器的实现，代码整理如：

#include"apue.h"

extern char **environ;
void clienterror(int fd,char *cause,char *errnum,char *shortmsg,char *longmsg)
{
    char buf[MAXLINE],body[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);
    rio_writen(fd,buf,strlen(buf));
    sprintf(buf,"Content-type:text/html\r\n");
    rio_writen(fd,buf,strlen(buf));
    sprintf(buf,"Content-length:%d\r\n\r\n",(int)strlen(body));
    rio_writen(fd,buf,strlen(buf));
    rio_writen(fd,body,strlen(body));
}


void read_requesthdrs(rio_t *rp)
{

    char buf[MAXLINE];
    rio_readlineb(rp,buf,MAXLINE);
    while(strcmp(buf,"\r\n"))
    {
        rio_readlineb(rp,buf,MAXLINE);
	printf("%s",buf);
    }
    return;
}

int parse_uri(char *uri,char *filename,char *cgiargs)
{
    char *ptr;
    printf("parse_uri(uri):%s\n",uri);
    if(!strstr(uri,"cgi-bin"))
    {
        strcpy(cgiargs,"");
	strcpy(filename,".");
	strcat(filename,uri);
	if(uri[strlen(uri)-1]=='/')
	    strcat(filename,"home.html");
        return 1;
    }

    else
    {
        ptr=index(uri,'?');
	if(ptr)
	{
	    strcpy(cgiargs,ptr+1);
	    *ptr='\0';
	}
	else
	    strcpy(cgiargs,"");
         strcpy(filename,".");
	 strcat(filename,uri);
	 return 0;

    }
}


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,".jpg"))
        strcpy(filetype,"image/jpeg"); 
    else
        strcpy(filetype,"text/plain");
}

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

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

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


void serve_static(int fd,char *filename,int filesize)
{

    int srcfd;
    char *srcp,filetype[MAXLINE],buf[MAXLINE];

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

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


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

    rio_readinitb(&rio,fd);
    rio_readlineb(&rio,buf,MAXLINE);
    sscanf(buf,"%s %s %s",method,uri,version);
    if(strcasecmp(method,"GET"))
    {
        clienterror(fd,method,"501","Not implemented","Tiny does not implemented this method");
	return;
    }

    read_requesthdrs(&rio);

    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 could'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 could't run the CGI program");
	    return;
	}
	serve_dynamic(fd,filename,cgiargs);
    }


}

int main(int argc,char **argv)
{
    int listenfd,connfd,port,clientlen;
    struct sockaddr_in clientaddr;

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

    port=atoi(argv[1]);

    listenfd=open_listenfd(port);
    while(1)
    {
        clientlen=sizeof(clientaddr);
	connfd=accept(listenfd,(SA*)&clientaddr,&clientlen);
	doit(connfd);
	close(connfd);
    }
}

我们可以直接使用浏览器测试上面的程序，比如当前服务器程序的目录下面有一个index.html，只要我们在浏览器中输入：

localhost:<port>/index.html就可以请求到index.html

服务器端收到的浏览器请求行如下：