/* twebserv.c - a threaded minimal web server (version 0.2) *    usage: tws portnumber * features: supports the GET command only *           runs in the current directory *           creates a thread to handle each request *           supports a special status URL to report internal state * building: cc twebserv.c socklib.c -lpthread -o twebserv */#include <stdio.h>#include <sys/types.h>#include <sys/stat.h>#include <string.h>#include <pthread.h>#include <stdlib.h>#include <unistd.h>#include <dirent.h>#include <time.h>/* server facts here */time_t	 server_started ;int	 server_bytes_sent;int	 server_requests;main(int ac, char *av[]){	int 		sock, fd;	int		*fdptr;	pthread_t	worker;	pthread_attr_t	attr;	void *handle_call(void *);	if ( ac == 1 ){		fprintf(stderr,"usage: tws portnum\n");		exit(1);	}	sock = make_server_socket( atoi(av[1]) );	if ( sock == -1 ) { perror("making socket"); exit(2); }	setup(&attr);	/* main loop here: take call, handle call in new thread  */	while(1){		fd = accept( sock, NULL, NULL );		server_requests++;		fdptr = malloc(sizeof(int));		*fdptr = fd;		pthread_create(&worker,&attr,handle_call,fdptr);	}}/* * initialize the status variables and * set the thread attribute to detached */setup(pthread_attr_t *attrp){	pthread_attr_init(attrp);	pthread_attr_setdetachstate(attrp,PTHREAD_CREATE_DETACHED);	time(&server_started);	server_requests = 0;	server_bytes_sent = 0;}void *handle_call(void *fdptr){	FILE	*fpin;	char	request[BUFSIZ];	int	fd ;	fd = *(int *)fdptr;	free(fdptr);				/* get fd from arg  */	fpin = fdopen(fd, "r");			/* buffer input	*/	fgets(request,BUFSIZ,fpin);		/* read client request */	printf("got a call on %d: request = %s", fd, request);	skip_rest_of_header(fpin);	process_rq(request, fd);		/* process client rq */	fclose(fpin);}/* ------------------------------------------------------ *   skip_rest_of_header(FILE *)   skip over all request info until a CRNL is seen   ------------------------------------------------------ */skip_rest_of_header(FILE *fp){	char	buf[BUFSIZ];	while( fgets(buf,BUFSIZ,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[BUFSIZ], arg[BUFSIZ];	if ( sscanf(rq, "%s%s", cmd, arg) != 2 )		return;	sanitize(arg);	printf("sanitized version is %s\n", arg);	if ( strcmp(cmd,"GET") != 0 )		not_implemented();	else if ( built_in(arg, fd) )		;	else if ( not_exist( arg ) )		do_404(arg, fd);	else if ( isadir( arg ) )		do_ls( arg, fd );	else		do_cat( arg, fd );}/* * make sure all paths are below the current directory */sanitize(char *str){	char	*src, *dest;	src = dest = str;	while( *src ){		if( strncmp(src,"/../",4) == 0 )			src += 3;		else if ( strncmp(src,"//",2) == 0 )			src++;		else			*dest++ = *src++;	}	*dest = '\0';	if ( *str == '/' )		strcpy(str,str+1);	if ( str[0]=='\0' || strcmp(str,"./")==0 || strcmp(str,"./..")==0 )		strcpy(str,".");}/* handle built-in URLs here.  Only one so far is "status" */built_in(char *arg, int fd){	FILE	*fp;	if ( strcmp(arg,"status") != 0 )		return 0;	http_reply(fd, &fp, 200, "OK", "text/plain",NULL);	fprintf(fp,"Server started: %s", ctime(&server_started));	fprintf(fp,"Total requests: %d\n", server_requests);	fprintf(fp,"Bytes sent out: %d\n", server_bytes_sent);	fclose(fp);	return 1;}http_reply(int fd, FILE **fpp, int code, char *msg, char *type, char *content){	FILE	*fp = fdopen(fd, "w");	int	bytes = 0;	if ( fp != NULL ){		bytes = fprintf(fp,"HTTP/1.0 %d %s\r\n", code, msg);		bytes += fprintf(fp,"Content-type: %s\r\n\r\n", type);		if ( content )			bytes += fprintf(fp,"%s\r\n", content);	}	fflush(fp);	if ( fpp )		*fpp = fp;	else		fclose(fp);	return bytes;}/* ------------------------------------------------------ *   simple functions first:        not_implemented(fd)      unimplemented HTTP command        and do_404(item,fd)     no such object   ------------------------------------------------------ */not_implemented(int fd){	http_reply(fd,NULL,501,"Not Implemented","text/plain",			"That command is not implemented");}do_404(char *item, int fd){	http_reply(fd,NULL,404,"Not Found","text/plain",			"The item you seek is not here");}/* ------------------------------------------------------ *   the directory listing section   isadir() uses stat, not_exist() uses stat   ------------------------------------------------------ */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){	DIR	      *dirptr;	struct dirent *direntp;	FILE	      *fp;	int	      bytes = 0;	bytes = http_reply(fd,&fp,200,"OK","text/plain",NULL);	bytes += fprintf(fp,"Listing of Directory %s\n", dir);	if ( (dirptr = opendir(dir)) != NULL ){		while( direntp = readdir(dirptr) ){			bytes += fprintf(fp, "%s\n", direntp->d_name);		}		closedir(dirptr);	}	fclose(fp);	server_bytes_sent += bytes;}/* ------------------------------------------------------ *   functions to cat files here.   file_type(filename) returns the 'extension': cat uses it   ------------------------------------------------------ */char * file_type(char *f){	char	*cp;	if ( (cp = strrchr(f, '.' )) != NULL )		return cp+1;	return "";}/* do_cat(filename,fd): sends header then the contents */do_cat(char *f, int fd){	char	*extension = file_type(f);	char	*type = "text/plain";	FILE	*fpsock, *fpfile;	int	c;	int	bytes = 0;	if ( strcmp(extension,"html") == 0 )		type = "text/html";	else if ( strcmp(extension, "gif") == 0 )		type = "image/gif";	else if ( strcmp(extension, "jpg") == 0 )		type = "image/jpeg";	else if ( strcmp(extension, "jpeg") == 0 )		type = "image/jpeg";	fpsock = fdopen(fd, "w");	fpfile = fopen( f , "r");	if ( fpsock != NULL && fpfile != NULL )	{		bytes = http_reply(fd,&fpsock,200,"OK",type,NULL);		while( (c = getc(fpfile) ) != EOF ){			putc(c, fpsock);			bytes++;		}		fclose(fpfile);		fclose(fpsock);	}	server_bytes_sent += bytes;}