put.c

Web 服务器的配置 对PUT请求的处理

/*                                                                   put.c
   **    PUT CGI-SCRIPT
   **
   **    (c) COPYRIGHT INRIA/MIT/W3C 1996.
   **    Please first read the full copyright statement in the file COPYRIGHT.
   **
   ** DISCLAIMER:
   **
   ** This is just an example script for handling PUT requests with the CERN
   ** server. It's provided in an as-is basis, without any guarantee over its
   ** functioning or any loss of data, accidental or intentional, coming 
   ** from its use. Users of this script are encouraged to fully review it
   ** before integrating it into their systems.
   **
   ** This script has been compiled with gcc and tested with the CERN 3.0 
   ** HTTP server, running under Solaris 2.5 and Linux 2.0.0.
   ** I tested the following clients against this server:
   ** Amaya 0.9a, Netscape Gold 3.0, and AOLpress 1.2 beta.
   ** Please email me if you use this script against/under something else.
   **
   ** You may find a link to the latest version of this script at:
   **      http://www.w3.org/pub/WWW/Amaya/PutCern.html
   **
   ** HISTORY:
   ** v0   20 May 96  Jose Kahan <[e-mail]>  Created from zero
   ** v1.0 24 Dec 96  Jose Kahan                 Improved error detection
   **                                            Added HTTP/1.x return codes
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/uio.h>
#include <sys/types.h>
#include <sys/stat.h>

#define LF "\r\n"

/***** HTTP status codes this script supports *****/
#define OK         1  /* 200 */
#define CREATED    2  /* 201 */
#define UPDATED    3  /* 204 */
#define ERROR     -1  /* 500 */

/***** USER CONFIGURABLE OPTIONS *******/

/*
** Here are some error status messages, in case you want to
** customize them yourself
*/

#define INVALID_PATH_MSG       "Server did not give a valid URL path"
#define INVALID_METHOD_MSG     "You must use a PUT method with this script"
#define INVALID_CONTENT_LENGTH_MSG "Server did not send a correct Content-length"

/*
** Change the following flags  to specify which will be the Unix access rights of
** the files that this script can create 
*/
#define FILE_RIGHTS S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH

/*
** Maximum number of bytes to read/write in a single operation 
*/
#define MAX_BUF_LEN  4048 

/*
** trace_on == 1 for a simple debug mode.
** Turned off by default
*/
int trace_on = 0; 

/*
** According to the HTTP/1.1 standard, there are at least two
** different response status that a PUT command can give:
** (201) when creating a new resource and (204) when updating
** it. To find out the state of a resource, the script does an extra
** system call. This wastes some time, and well, today's
** browsers are satisfied with the 204 response. Thus, undefine
** the following macro if you don't need this feature.
 */

#define CREATE_UPDATE

/*
**  define the following macro when running the script on a
**  fully compliant HTTP/1.1 server. It'll activate
**  the generation of a Location header to be sent together
**  with an HTTP/1.1 201 response.
*/
/**
#define HTTP_11
**/

/***** END OF USER CONFIGURABLE OPTIONS ******/

extern char **environ;
extern int errno;
extern char *sys_errlist[];

#if defined(__svr4__)
#define CATCH_SIG
#endif

/*
**  Function Prototypes
**  -------------------
*/

void trace (char *trace_msg);
int copy_content (char *filename, long cl, char ** status_msg);
void dump_result (char *url, char *status_msg, int status);
static void SetSignal (void);

/* ------------------------------------------------------------------------- */

/*
**  trace
**  -----
**  Prints error messages --- for debugging
*/

void
trace (char *trace_msg)
{
  if (trace_on)
    fprintf (stderr, "PUT TRACE: %s\n", trace_msg);
}


/*
**  dump_result
**  -----------
**  Outputs the PUT result thru  stdout, according to the CGI
**  specification.
*/
void
dump_result (char *url, char *status_msg, int status)
{
  switch(status) {

  case OK:
    /* not used for the moment, but it does not hurt to have this case
       here */
    printf ("Status: 200%s", LF);
    printf ("Content-Type: text/html%s%s", LF, LF);
    printf ("<HTML><HEAD><TITLE>PUT success</TITLE></HEAD>%s"
            "<BODY><P>Created the following resource:<CODE>%s</CODE>"
	    "</P>%s</BODY></HTML>",LF,LF,url);
    break;

  case UPDATED:
    trace ("Updating a file");

    printf ("Status: 204%s%s", LF, LF); 
    break;

  case CREATED:
    trace ("Creating a file");

    printf ("Status: 201%s%s", LF, LF);

#ifdef HTTP_11
    /*    printf ("Location:%s%s", url, LF);*/
    printf ("Content-Type: text/html%s%s", LF, LF);
    printf ("<HTML><HEAD><TITLE>PUT success</TITLE></HEAD>%s"
            "<BODY><P>Created the following resource:</P><P><CODE>%s</CODE>"
	    "</P>%s</BODY></HTML>",LF, LF, url);
#endif /* HTTP/1.1 */
    break;
  
  case ERROR:
  default:
    trace ("Uh oh, an error ...");

    printf ("Status: 500 cgi PUT script error%s", LF);
    printf ("Content-Type: text/html%s%s",LF,LF); 
    printf ("<HTML><HEAD><TITLE>cgi PUT script error</TITLE></HEAD>\n");
    if(url && url[0] != '\0')
      printf("<BODY><P>Could not save the following URL:</P><P><CODE>%s</CODE></P>\n", url);
    else
      printf("<BODY><P>Could not save the URL</P>\n");
    if(status_msg && status_msg[0] != '\0')
      printf("<P>Reason: <CODE>%s</CODE></P>\n", status_msg);
  printf("</BODY></HTML>");
  break;
  } /* switch */
}


/*
**  SetSignal
**  ---------
**  This function sets up signal handlers. This might not be necessary to
**  call if the application has its own handlers.
*/
static void
SetSignal (void)
{
  /* On some systems (SYSV) it is necessary to catch the SIGPIPE signal
  ** when attemting to connect to a remote host where you normally should
  ** get `connection refused' back
  */
  if (signal (SIGPIPE, SIG_IGN) == SIG_ERR)
	trace("HTSignal.... Can't catch SIGPIPE");
  else
	trace("HTSignal.... Ignoring SIGPIPE");
}


/*
**  copy_content
**  ------------
**  Creates a filename and then copies cl bytes from stdin into it 
**  If there's an error, it returns ERROR and sets status_msg to
**  the corresponding Unix system error message. Otherwise, it
**  returns either CREATED or UPDATED, depending whether the file
**  already existed or not.
 */ 
int
copy_content (char *filename, long cl, char **status_msg)
{
  char buffer[MAX_BUF_LEN];
  int fd_out;
  int nb_elements_read, nb_elements_write;
  int buf_len;
  int status;

  /*
  ** this is for verifying if the file already existed, to be compliant
  ** with HTTP/1.1. 
  */

#ifdef CREATE_UPDATE
  if((fd_out = open (filename, O_EXCL | O_WRONLY | O_CREAT | O_TRUNC, FILE_RIGHTS)) == -1) {
    if (errno == EEXIST) {
      trace("File existed !");
      status = UPDATED;
      if ((fd_out = creat (filename, FILE_RIGHTS)) == -1) {
	*status_msg = sys_errlist[errno];
	trace (*status_msg);
	return (ERROR);
      }
    }
    else {
      *status_msg = sys_errlist[errno];
      trace (*status_msg);
      return(ERROR);
    }
  } else
    status = CREATED;
#else
  if ((fd_out = creat (filename, FILE_RIGHTS)) == -1) {
    *status_msg = sys_errlist[errno];
    trace (*status_msg);
    return (ERROR);
  }
  else 
    status = CREATED;
#endif /* CREATE_UPDATE */
 
  buf_len = MAX_BUF_LEN;

  while (status != ERROR && cl) {
    if (cl < buf_len)
	buf_len = cl;
    nb_elements_read = read (0, buffer, buf_len);
    if (nb_elements_read == -1) {
      *status_msg = sys_errlist[errno];
      trace (*status_msg);
      status = ERROR;
      break;
    }
 
    nb_elements_write = write (fd_out, buffer, nb_elements_read);
    if (nb_elements_write == -1 || nb_elements_write != nb_elements_read) {
      *status_msg = sys_errlist[errno];
      trace (*status_msg);
      status = ERROR;
      break;
    }
    cl = cl - nb_elements_read;
  }

  if (close (fd_out) == -1) {
    *status_msg = sys_errlist[errno];
    trace (*status_msg);
    status = ERROR;
  }

  return (status);
}
        

/*
**  main
**  ----
**  Does not receives any direct input parameters. They come from
**  the Unix environment variables, according to the
**  CGI specification.
*/

int
main (int argc, char *argv[])
{
  char *filename;
  char *method;
  char *url;
  char *status_msg;
  char *pcl;
  long cl;
  int status;

  trace ("I\'m alive (PUT)");

#ifdef CATCH_SIG
   SetSignal ();
#endif

  /*
  ** Read and control the CGI environment variables
  */

  trace ("Reading CGI environment variables");
  method = getenv ("REQUEST_METHOD");
  url = getenv ("PATH_INFO");
  filename = getenv ("PATH_TRANSLATED");
  pcl = getenv ("CONTENT_LENGTH");

  if(!url || !url[0] || !filename || !filename[0]) {
    status = ERROR;
    status_msg = INVALID_PATH_MSG;
    url = NULL;
    trace(status_msg);
  }
  else if (!method || strcmp(method, "PUT")) {
    status = ERROR;
    status_msg = INVALID_METHOD_MSG;
    trace(status_msg);
  }
  else if (!pcl || !pcl[0]) {
    status = ERROR;
    status_msg = INVALID_CONTENT_LENGTH_MSG;
    trace(status_msg);
  }
  else {
    if(trace_on)
      fprintf (stderr, "REQUEST_METHOD = %s\n"
	               "PATH_INFO = %s\n"
	               "PATH_TRANSLATED = %s\n"
	               "CONTENT_LENGTH = %s\n",
	                method, url, filename, pcl);

    /* set the number of bytes ( content length) to read */
    cl = atol (pcl);
    /* 
    **try to save the file
    */
    status = copy_content(filename, cl, &status_msg);
  } /* if-else */

  if(trace_on)
    fprintf(stderr,"status is %d\n", status);

  dump_result (url, status_msg, status);

  exit(0); 
}


/*
** end of module put.c
*/