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LIB_resolve_addresses.php
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/
LIB_resolve_addresses.php
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<?php
/*
########################################################################
Copyright 2007, Michael Schrenk
This software is designed for use with the book,
"Webbots, Spiders, and Screen Scarpers", Michael Schrenk, 2007 No Starch Press, San Francisco CA
W3C® SOFTWARE NOTICE AND LICENSE
This work (and included software, documentation such as READMEs, or other
related items) is being provided by the copyright holders under the following license.
By obtaining, using and/or copying this work, you (the licensee) agree that you have read,
understood, and will comply with the following terms and conditions.
Permission to copy, modify, and distribute this software and its documentation, with or
without modification, for any purpose and without fee or royalty is hereby granted, provided
that you include the following on ALL copies of the software and documentation or portions thereof,
including modifications:
1. The full text of this NOTICE in a location viewable to users of the redistributed
or derivative work.
2. Any pre-existing intellectual property disclaimers, notices, or terms and conditions.
If none exist, the W3C Software Short Notice should be included (hypertext is preferred,
text is permitted) within the body of any redistributed or derivative code.
3. Notice of any changes or modifications to the files, including the date changes were made.
(We recommend you provide URIs to the location from which the code is derived.)
THIS SOFTWARE AND DOCUMENTATION IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE NO REPRESENTATIONS OR
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD
PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS.
COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT
OF ANY USE OF THE SOFTWARE OR DOCUMENTATION.
The name and trademarks of copyright holders may NOT be used in advertising or publicity pertaining to the
software without specific, written prior permission. Title to copyright in this software and any associated
documentation will at all times remain with copyright holders.
########################################################################
*/
########################################################################
#
# LIB_resolve_addresses
#
# This library provides routines that create fully resolved
# web addresses
#
#-----------------------------------------------------------------------
# FUNCTIONS
#
# resolve_address()
# This function returns fully resolved URLs for the $link
# which could be an images, css, javascript file, etc.
#
# get_base_page_address()
# Search from right to left for first occurrence of "/".
# Then use everything from the left of that character as the
# page base address.
#
# get_base_domain_address()
# Note that the base DOMAIN address is different than the base
# PAGE address. The base page address may indicate a directory
# structure, while the base domain address is simply the
# domain, without any files or directories.
#
#-----------------------------------------------------------------------
/***********************************************************************
resolve_address($link, $page_base)
-------------------------------------------------------------
DESCRIPTION:
This function returns fully resolved URLs for the $link
which could be an images, css, javascript file, etc.
RETURNS:
A fully resolved URL for the $link
***********************************************************************/
function resolve_address($link, $page_base)
{
#----------------------------------------------------------
# CONDITION INCOMING LINK ADDRESS
#
$link = trim($link);
$page_base = trim($page_base);
# if there isn't one, put a "/" at the end of the $page_base
$page_base = trim($page_base);
if( (strrpos($page_base, "/")+1) != strlen($page_base) )
$page_base = $page_base."/";
# remove unwanted characters from $link
$link = str_replace(";", "", $link); // remove ; characters
$link = str_replace("\"", "", $link); // remove " characters
$link = str_replace("'", "", $link); // remove ' characters
$abs_address = $page_base.$link;
$abs_address = str_replace("/./", "/", $abs_address);
$abs_done = 0;
#----------------------------------------------------------
# LOOK FOR REFERENCES TO THE BASE DOMAIN ADDRESS
#----------------------------------------------------------
# There are essentially four types of addresses to resolve:
# 1. References to the base domain address
# 2. References to higher directories
# 3. References to the base directory
# 4. Addresses that are alreday fully resolved
#
if($abs_done==0)
{
# Use domain base address if $link starts with "/"
if (substr($link, 0, 1) == "/")
{
// find the left_most "."
$pos_left_most_dot = strrpos($page_base, ".");
# Find the left-most "/" in $page_base after the dot
for($xx=$pos_left_most_dot; $xx<strlen($page_base); $xx++)
{
if( substr($page_base, $xx, 1)=="/")
break;
}
$domain_base_address = get_base_domain_address($page_base);
$abs_address = $domain_base_address.$link;
$abs_done=1;
}
}
#----------------------------------------------------------
# LOOK FOR REFERENCES TO HIGHER DIRECTORIES
#
if($abs_done==0)
{
if (substr($link, 0, 3) == "../")
{
$page_base=trim($page_base);
$right_most_slash = strrpos($page_base, "/");
// remove slash if at end of $page base
if($right_most_slash==strlen($page_base)-1)
{
$page_base = substr($page_base, 0, strlen($page_base)-1);
$right_most_slash = strrpos($page_base, "/");
}
if ($right_most_slash<8)
$unadjusted_base_address = $page_base;
$not_done=TRUE;
while($not_done)
{
// bring page base back one level
list($page_base, $link) = move_address_back_one_level($page_base, $link);
if(substr($link, 0, 3)!="../")
$not_done=FALSE;
}
if(isset($unadjusted_base_address))
$abs_address = $unadjusted_base_address."/".$link;
else
$abs_address = $page_base."/".$link;
$abs_done=1;
}
}
#----------------------------------------------------------
# LOOK FOR REFERENCES TO BASE DIRECTORY
#
if($abs_done==0)
{
if (substr($link, 0, "1") == "/")
{
$link = substr($link, 1, strlen($link)-1); // remove leading "/"
$abs_address = $page_base.$link; // combine object with base address
$abs_done=1;
}
}
#----------------------------------------------------------
# LOOK FOR REFERENCES THAT ARE ALREADY ABSOLUTE
#
if($abs_done==0)
{
if (substr($link, 0, 4) == "http")
{
$abs_address = $link;
$abs_done=1;
}
}
#----------------------------------------------------------
# ADD PROTOCOL IDENTIFIER IF NEEDED
#
if( (substr($abs_address, 0, 7)!="http://") && (substr($abs_address, 0, 8)!="https://") )
$abs_address = "http://".$abs_address;
return $abs_address;
}
/***********************************************************************
get_base_page_address($url)
-------------------------------------------------------------
DESCRIPTION:
Search from right to left for first occurrence of "/".
Then use everything from the left of that character as the page
base address.
If the position of "/" is less than 7, then that character is
part of an URL that is directly referenced.
(i.e. "http://www.someplace.com".
With direct URL references, always make sure that the base page
address always ends in a "\".
INPUTS:
$url
RETURNS:
The base page address for $url
***********************************************************************/
function get_base_page_address($url)
{
$slash_position = strrpos($url, "/");
if ($slash_position>8)
$page_base = substr($url, 0, $slash_position+1); // "$slash_position+1" to include the "/".
else
{
$page_base = $url; // $url is already the page base, without modification.
if($slash_position!=strlen($url))
$page_base=$page_base."/";
}
# If the page base ends with a \\, replace with a \
$last_two_characters = substr($page_base, strlen($page_base)-2, 2);
if($last_two_characters=="//")
$page_base = substr($page_base, 0, strlen($page_base)-1);
return $page_base;
}
/***********************************************************************
get_base_domain_address($page_base)
-------------------------------------------------------------
DESCRIPTION:
Note that the base DOMAIN address is different than the base
PAGE address. The base page address may indicate a directory
structure, while the base domain address is simply the domain,
without any files or directories.
The base domain address found by taking everything to the right
of the first "/" once past the initial "/"'s found after the
protocol specifier (http:// or https://)
INPUTS:
$page_base, (from get_base_page_address)
RETURNS:
The base page domain address for URL
***********************************************************************/
function get_base_domain_address($page_base)
{
for ($pointer=8; $pointer<strlen($page_base); $pointer++)
{
if (substr($page_base, $pointer, 1)=="/")
{
$domain_base=substr($page_base, 0, $pointer);
break;
}
}
$last_two_characters = substr($page_base, strlen($page_base)-2, 2);
if($last_two_characters=="//")
$page_base = substr($page_base, 0, strlen($page_base)-1);
return $domain_base;
}
/***********************************************************************
move_address_back_one_level($page_base, $object_source)
-------------------------------------------------------------
DESCRIPTION:
This function is used by the library and not intended for
external use.
-------------------------------------------------------------
*/
function move_address_back_one_level($page_base, $object_source)
{
// bring page base back one leve
$right_most_slash = strrpos($page_base, "/");
$new_page_base = substr($page_base, 0, $right_most_slash);
// remove "../" from front of object_source
$object_source = substr($object_source, 3, strlen($object_source)-3);
$return_array[0]=$new_page_base;
$return_array[1]=$object_source;
return $return_array;
}
?>