Solved

Retrieving remote file information

Posted on 1997-07-07
2
150 Views
Last Modified: 2013-12-25
Is it possible to use PERL and/or CGI to query a remote server to retrieve file information?  Basically, I am looking to get the date created or last modified date of files on different servers.  If it is possible to do this, how is it done (please provide code if possible).  What information can you retrieve about remote files on servers you access anonymously?  Thanks for your assistance.  
0
Comment
Question by:mtob
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 5

Accepted Solution

by:
julio011597 earned 100 total points
ID: 1828904
Sure, i'll give a ready routine to get file informations through use of the web server's HEAD method.

You can embedd this routine anywhere you need; just pass it the right parameters - this means you could put it into a program to invoke from the shell, or into a CGI.

Please check function return types and include files on your OS, since there may be slight differences.

--//--
#include <stdlib.h>
#include <stdio.h>
#include <string.h>     /* bzero() and bcopy() */
#include <netdb.h>      /* gethostbyname() */
#include <sys/socket.h> /* socket() and connect() */
#include <arpa/inet.h>  /* htons() */
#include <errno.h>      /* errno */

#define PORT 80

/* get_url()
 * answer: file to write to (must be already open for writing - it may be stdin)
 * host: e.g. "www.experts-exchange.com"
 * url : e.g. "/topics/comp/lang/c"
 * err_str: to eventually store an error message
 *
 * returns 0 if succesful, errno otherwise
 */

int get_url(FILE *answer, const char *host, const char *url, char err_str[])
{
  int sock;
  struct hostent *hep;
  struct sockaddr_in sai;
  FILE *infile, *outfile;
  char buff[BUFSIZ];

  if(!(hep = gethostbyname(host))) {
    strcpy(err_str, "gethostbyname error");
    return errno;
  }
  if((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
    strcpy(err_str, "socket error");
    return errno;
  }

  bzero((char *)&sai, sizeof(struct sockaddr_in));
  sai.sin_family = AF_INET;
  sai.sin_port = htons((unsigned short)PORT);
  bcopy(hep->h_addr, (char *)&(sai.sin_addr.s_addr), hep->h_length); /* note: could just be 'sai.sin_addr' */

  if(connect(sock, (struct sockaddr *)&sai, sizeof(sai)) == -1) {
    strcpy(err_str, "connect error");
    return errno;
  }

  /* fine: now we are connected */
  /* let's work with stdio */
  if(!(infile = fdopen(sock, "r"))) {
    strcpy(err_str, "fdopen(in) error");
    return errno;
  }
  if(!(outfile = fdopen(sock, "w"))) {
    strcpy(err_str, "fdopen(out) error");
    return errno;
  }

  /* now, the query: i'll leave error checking now on! */
  fprintf(outfile, "HEAD %s HTTP1.0\n", url);
  fflush(outfile); /* this is mandatory: outfile would buffer */

  while(fgets(buff, BUFSIZ, infile)) fputs(buff, answer);
  fflush(answer); /* this is not mandatory:) */

  /* cleanup */
  /* note: the two fclose's are also mandatory: */
  /* the file tables are not automagically deallocated */
  /* if you just close the socket (at least on my system), */
  /* and you could go out of resources if you loop */
  /* to connect to more than one site */
  fclose(infile); fclose(outfile);
  close(sock);

  return 0;
}
--//--

Cheers, julio

P.S. maybe this is worth more than 100 points...
0
 

Author Comment

by:mtob
ID: 1828905
You're right, it was worth more.  Thank you very much.  If you could help though, is there a PERL way of doing it.  I can do it through C if I have to but would much rather through PERL.
0

Featured Post

Get 15 Days FREE Full-Featured Trial

Benefit from a mission critical IT monitoring with Monitis Premium or get it FREE for your entry level monitoring needs.
-Over 200,000 users
-More than 300,000 websites monitored
-Used in 197 countries
-Recommended by 98% of users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Making a simple AJAX shopping cart Couple years ago I made my first shopping cart, I used iframe and JavaScript, it was very good at that time, there were no sessions or AJAX, I used cookies on clients machine. Today we have more advanced techno…
Active Directory replication delay is the cause to many problems.  Here is a super easy script to force Active Directory replication to all sites with by using an elevated PowerShell command prompt, and a tool to verify your changes.
Learn the basics of strings in Python: declaration, operations, indices, and slicing. Strings are declared with quotations; for example: s = "string": Strings are immutable.: Strings may be concatenated or multiplied using the addition and multiplic…
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…

617 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question