一个web服务器的实现 - Chinaunix

/* webserv.c - a web server
* build: gcc webserv.c -o webserv
*/
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/stat.h>
#include <time.h>
#include <string.h>
#define HOSTLEN 256
#define BACKLOG 1
main(int ac, char *av[])
{
int sock, fd;
FILE *fpin;
char request[BUFSIZ];
if ( ac == 1 ){
fprintf(stderr,"usage: ws portnum\n");
exit(1);
}
sock = make_server_socket( atoi(av[1]) );
if ( sock == -1 ) exit(2);
/* main loop here */
while(1){
/* take a call and buffer it */
fd = accept( sock, NULL, NULL );
fpin = fdopen(fd, "r" );
/* read request */
fgets(request,BUFSIZ,fpin);
printf("got a call: request = %s", request);
read_til_crnl(fpin);
/* do what client asks */
process_rq(request, fd);
fclose(fpin);
}
}
/* ------------------------------------------------------ *
make_server_socket(int portnum)
创建一个服务器套接字,并调用listen监听
------------------------------------------------------ */
int make_server_socket(int portnum)
{
return make_server_socket_q(portnum, BACKLOG);
}
int make_server_socket_q(int portnum, int backlog)
{
struct sockaddr_in saddr; /* build our address here */
struct hostent *hp; /* this is part of our */
char hostname[HOSTLEN]; /* address */
int sock_id; /* the socket */
sock_id = socket(PF_INET, SOCK_STREAM, 0); /* get a socket */
if ( sock_id == -1 )
return -1;
/** build address and bind it to socket **/
bzero((void *)&saddr, sizeof(saddr)); /* clear out struct */
gethostname(hostname, HOSTLEN); /* where am I ? */
hp = gethostbyname(hostname); /* get info about host */
/* fill in host part */
bcopy( (void *)hp->h_addr, (void *)&saddr.sin_addr, hp->h_length);
saddr.sin_port = htons(portnum); /* fill in socket port */
saddr.sin_family = AF_INET ; /* fill in addr family */
if ( bind(sock_id, (struct sockaddr *)&saddr, sizeof(saddr)) != 0 )
return -1;
/** arrange for incoming calls **/
if ( listen(sock_id, backlog) != 0 )
return -1;
return sock_id;
}
/* ------------------------------------------------------ *
read_til_crnl(FILE *)
skip over all request info until a CRNL is seen
------------------------------------------------------ */
read_til_crnl(FILE *fp)
{
char buf[BUFSIZ];
while( fgets(buf,BUFSIZ,fp) != NULL && strcmp(buf,"\r\n") != 0 )
;
}
/* ------------------------------------------------------ *
process_rq( char *rq, int fd )
分析客户端的请求，分析然后做出相应的应答
rq is HTTP command: GET /foo/bar.html HTTP/1.0
------------------------------------------------------ */
process_rq( char *rq, int fd )
{
char cmd[BUFSIZ], arg[BUFSIZ];
/* create 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 functions 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(fp, "Content-type: text/plain\r\n");
fprintf(fp, "\r\n");
fprintf(fp, "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: text/plain\r\n");
fprintf(fp, "\r\n");
fprintf(fp, "The item you requested: %s\r\nis not found\r\n",
item);
fclose(fp);
}
/* ------------------------------------------------------ *
the directory listing section
isadir() uses stat, not_exist() uses stat
do_ls runs ls. It should not
------------------------------------------------------ */
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)
/* returns 'extension' of file */
{
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/jpeg";
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);
}

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/* webserv_pthread.c - a threaded web server
* building: gcc webserv_pthread.c -lpthread -o webserv_pthread
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/stat.h>
#include <string.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <dirent.h>
#include <time.h>
#define HOSTLEN 256
#define BACKLOG 1
/* 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);
}
}
/* ------------------------------------------------------ *
make_server_socket(int portnum)
创建一个服务器套接字,并调用listen监听
------------------------------------------------------ */
int make_server_socket_q(int , int );
int make_server_socket(int portnum)
{
return make_server_socket_q(portnum, BACKLOG);
}
int make_server_socket_q(int portnum, int backlog)
{
struct sockaddr_in saddr; /* build our address here */
struct hostent *hp; /* this is part of our */
char hostname[HOSTLEN]; /* address */
int sock_id; /* the socket */
sock_id = socket(PF_INET, SOCK_STREAM, 0); /* get a socket */
if ( sock_id == -1 )
return -1;
/** build address and bind it to socket **/
bzero((void *)&saddr, sizeof(saddr)); /* clear out struct */
gethostname(hostname, HOSTLEN); /* where am I ? */
hp = gethostbyname(hostname); /* get info about host */
/* fill in host part */
bcopy( (void *)hp->h_addr, (void *)&saddr.sin_addr, hp->h_length);
saddr.sin_port = htons(portnum); /* fill in socket port */
saddr.sin_family = AF_INET ; /* fill in addr family */
if ( bind(sock_id, (struct sockaddr *)&saddr, sizeof(saddr)) != 0 )
return -1;
/** arrange for incoming calls **/
if ( listen(sock_id, backlog) != 0 )
return -1;
return sock_id;
}
/*
* 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;
}

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