webserver.c

这是linux上的一个webserver的示例程式,是我是一实验性的作品.希望对大家有帮助.

/*
the sample web server -----based in the HTTP  
*/

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <socklib.c>

#define  BUFFSIZE  1024
#define  oops(msg)   {perror(msg);exit(1);}
main(int arvc,char *argv[])
{
	      int sock,fd;
	      FILE *fpin;
	      char request[BUFFSIZE];
	      if(argc == 1){
	      	   fprintf(stderr,"usage : ws portnum \n");
	      	   exit(1)
	      	  }
	       
	       sock = make_server_socket(atoi(argv[1]));
	       if(sock == -1)
	       	  oops("build the socket")
	       	  
	       	  
	      while(1){
	      	     /*take a call and buffer it*/
	      	     fd=accept(sock,NULL,NULL);
	      	     fpin=fdopen(fd,"r");
	      	     /*read request*/
	      	     fgets(request,BUFFSIZE,fpin);
	      	     printf("got a call : request = %s",request);
	      	     read_til_crnl(fpin);
	      	     /*do what client asks*/
	      	     process_rq(request,fd);
	      	     fclose(fpin);
	      	    
	      }

  }
  
  
 /*------------------------------------------------------------
 read_til_crnl(FILE *)
 --------------------------------------------------------------*/ 
 read_til_crnl(FILE *fp)
{
	  char buf[BUFFSIZE];
	  while(fgets(buf,BUFFSIZE,fp) != NULL && strcmp(buf,"\r\n")!=0);
	 
} 
 
/*------------------------------------------------------------
process_rq(char *rq,int fd)
do what the request asks for and write reply to fd
handles request in a new process
rq is HTTP command : GET /foo/bar.html  HTTP/1.0
----------------------------------------------------------------*/ 

process_rq(char *rq, int fd)
{
	 char cmd[BUFFSIZE] ,arg[BUFFSIZE];
	 /*creat a new process and return if not the child*/
	 if(fork()!=0)
	 	   return;
	 strcpy(arg,"./"); /*precede args with ./*/
	 
	 if(sscanf(rq,"%s%s",cmd,arg+2)!=2)	
	 	   return;
	 if(strcmp(cmd,"GET")!=0)
   	 	   cannot_do(fd);
	 else if(not_exist(arg))
	 	   do_404(arg,fd);
	 else if(isadir(arg))
	 	   do_ls(arg,fd);
	 else if(ends_in_cgi(arg))
	 	   do_exec(arg,fd);
	 else
	 	   do_cat(arg,fd);
	
	
	}
 
 
 
/*----------------------------------------------------------------------
the reply header thing:all functions need one 
if content_type is NULL then don't send content type
------------------------------------------------------------------------*/ 
 
 header(FILE *fp , char *content_type)
 {
 	    fprintf(fp,"HTTP/1.0 200 OK\r\n");
 	    if(content_type)
 	    	fprintf(fp,"Content-type: %s\r\n",content_type);
 	}
 
/*---------------------------------------------------------------------
simple function first:
     cannot_do(fd)   unimplemented HTTP command
  and do_404(item,fd) no such object
-----------------------------------------------------------------------*/ 
 
 cannot_do(int fd)
 {
 	   FILE *fp = fdopen(fd,"w");
 	   fprintf(fp,"HTTP/1.0 501 Not Implemented\r\n");
 	   fprintf(fd,"Content-type:text/plain\r\n");
 	   fprintf(fd,"\r\n");
 	   fprintf(fd,"That command is not yet implemented\r\n");
 	   fclose(fp);
 	 }
 
do_404(char *item ,int fd)
{
	  FILE *fp = fdopen(fd,"w"); 
	  fprintf(fp,"HTTP/1.0 404 Not Found\r\n");
	  fprintf(fp,"Content-type:t:text/plain\r\n");
	  fprintf(fp,"\r\n");
	  
	  fprintf(fp,"The item you requested :$s\r\nis not found\r\n",item);
	  fclose(fp);
	 }
 
 
isadir(char *f)
{
	  struct stat info;
	  return(stat(f,&info) != -1 && S_ISDIR(info.st_mode));
	 
	
	}
	
not_exist(char *f)
{
	struct stat info;
	return(stat(f,&info) == -1);
  
}


do_ls(char *dir,int fd)
{
	FILE *fp;
	fp = fdopen(fd,"w");
	header(fp,"text/plain");
	fprintf(fp,"\r\n");
	fflush(fp);
	
	dup2(fd,1);
	dup2(fd,2);
	close(fd);
	execlp("ls","ls","-l",dir,NULL);
	perror(dir);
	exit(1); 

}


/*----------------------------------------------------------------------------------------'
the cgi stuff . function to check extension and one to run the program.
-------------------------------------------------------------------------------------------*/
char *file_type(char *f)
{
	char *cp;
	if((cp = strrchr(f,'. ')) != NULL)
		return cp+1;
	return "";
}

ends_in_cgi(char *f)
{
	return(strcmp(file_type(f),"cgi") == 0);

}

do_exec(char *prog,int fd)
{
	FILE *fp;
	
	fp = fdopen(fd,"w");
	header(fp,NULL)
	fflush(fp);
	dup2(fd,1);
	dup2(fd,2);
	close(fd);
	execl(prog,prog,NULL);
	perror(prog);

}


/*------------------------------------------------------------------------------------------
do_cat(filename,fd)
sends back contents after a header
-------------------------------------------------------------------------------------------*/
do_cat(char *f,int fd)
{
	char *extension = file_type(f);
	char *content = "text/plain";
	FILE *fpsock,*fpfile;
	
	int  c;
	
	if(strcmp(extension,"html") == 0)
		content = "text/html";
	else if(strcmp(extension,"gif") == 0)
		content = "image/gif";
	else if(strcmp(extension,"jpg")== 0)
		content = "image/jpg";
	else if(strcmp(extension,"jpeg") == 0)
		content = "image/jpeg";
	
	fpsock = fdopen(fd,"w");
	fpfile = fopen(f,"r");
	if(fpsock != NULL && fpfile != NULL)
	{
		header(fpsock,content);
		fprintf(fpsock ,"\r\n");
		while((c = getc(fpfile)) != EOF)
			putc(c,fpsock);
		fclose(fpfile);
		fclose(fpsock);
	
	
	}
	exit(0);
}