#!/usr/local/bin/perl
#
# checklinks.pl
#
# This script extracts all links from a HTML page and checks their validity.
# Written to use 'curl' for URL checking.
#
# Author: Daniel Stenberg <Daniel.Stenberg@sth.frontec.se>
# Version: 0.7 Sept 30, 1998
#
# HISTORY
#
# 0.5 - Cuts off the #-part from links before checking.
#
# 0.6 - Now deals with error codes 3XX better and follows the Location:
#       properly.
#     - Added the -x flag that only checks http:// -links
#
# 0.7 - Ok, http://www.viunga.se/main.html didn't realize this had no path
#       but a document. Now it does.
#
#

$in="";

 argv:
if($ARGV[0] eq "-v" ) {
    $verbose = 1;
    shift @ARGV;
    goto argv;
}
elsif($ARGV[0] eq "-i" ) {
    $usestdin = 1;
    shift @ARGV;
    goto argv;
}
elsif($ARGV[0] eq "-l" ) {
    $linenumber = 1;
    shift @ARGV;
    goto argv;
}
elsif($ARGV[0] eq "-h" ) {
    $help = 1;
    shift @ARGV;
    goto argv;
}
elsif($ARGV[0] eq "-x" ) {
    $external = 1;
    shift @ARGV;
    goto argv;
}

$geturl = $ARGV[0];

if(($geturl eq "") || $help) {
    print  "Usage: $0 [-hilvx] <full URL>\n",
    " Use a traling slash for directory URLs!\n",
    " -h  This help text\n",
    " -i  Read the initial page from stdin\n",
    " -l  Line number report for BAD links\n",
    " -v  Verbose mode\n",
    " -x  Check non-local (external?) links only\n";
    exit;
}

if($ARGV[1] eq "-") {
    print "We use stdin!\n";
    $usestdin = 1;
}

# This is necessary from where I tried this:
#$proxy =" -x 194.237.142.41:80";

# linkchecker, URL will be appended to the right of this command line
# this is the one using HEAD:
$linkcheck = "curl -s -m 20 -I$proxy";

# as a second attempt, this will be used. This is not using HEAD but will
# get the whole frigging document!
$linkcheckfull = "curl -s -m 20 -i$proxy";

# htmlget, URL will be appended to the right of this command line
$htmlget = "curl -s$proxy";

# Parse the input URL and split it into the relevant parts:

sub SplitURL {
    my $inurl = $_[0];

    if($inurl=~ /^([^:]+):\/\/([^\/]*)\/(.*)\/(.*)/ ) {
	$getprotocol = $1;
	$getserver = $2;
	$getpath = $3;
	$getdocument = $4;
    }
    elsif ($inurl=~ /^([^:]+):\/\/([^\/]*)\/(.*)/ ) {
	$getprotocol = $1;
	$getserver = $2;
	$getpath = $3;
	$getdocument = "";
	
	if($getpath !~ /\//) {
	    $getpath ="";
	    $getdocument = $3;
	}
    
    }
    elsif ($inurl=~ /^([^:]+):\/\/(.*)/ ) {
	$getprotocol = $1;
	$getserver = $2;
	$getpath = "";
	$getdocument = "";
    }
    else {
	print "Couldn't parse the specified URL, retry please!\n";
	exit;
    }
}

&SplitURL($geturl);

#print "protocol = $getprotocol\n";
#print "server = $getserver\n";
#print "path = $getpath\n";
#print "document = $getdocument\n";
#exit;

if(!$usestdin) {
    open(HEADGET, "$linkcheck $geturl|") ||
	die "Couldn't get web page for some reason";
  headget:
    while(<HEADGET>) {
#	print $_;
	if($_ =~ /HTTP\/.*3\d\d /) {
	    $pagemoved=1;
	}
	elsif($pagemoved &&
	       ($_ =~ /^Location: (.*)/)) {
	    $geturl = $1;

	    &SplitURL($geturl);

	    $pagemoved++;
	    last headget;
	}
    }
    close(HEADGET);

    if($pagemoved == 1) {
	print "Page is moved but we don't know where. Did you forget the ",
	"traling slash?\n";
	exit;
    }

    open(WEBGET, "$htmlget $geturl|") ||
	die "Couldn't get web page for some reason";

    while(<WEBGET>) {
	$line = $_;
	push @indoc, $line;
	$line=~ s/\n//g;
	$line=~ s/\r//g;
#    print $line."\n";
	$in=$in.$line;
    }

    close(WEBGET);
}
else {
    while(<STDIN>) {
	$line = $_;
	push @indoc, $line;
	$line=~ s/\n//g;
	$line=~ s/\r//g;
	$in=$in.$line;
    }
}

#print length($in)."\n";

sub LinkWorks {
    my $check = $_[0];

#   URL encode:
#    $check =~s/([^a-zA-Z0-9_:\/.-])/uc sprintf("%%%02x",ord($1))/eg;

    @doc = `$linkcheck \"$check\"`;

    $head = 1;

#    print "COMMAND: $linkcheck \"$check\"\n";
#    print $doc[0]."\n";

  boo:
    if( $doc[0] =~ /^HTTP[^ ]+ (\d+)/ ) {
	$error = $1;

	if($error < 400 ) {
	    return "GOOD";
	}
	else {
	    
	    if($head && ($error >= 500)) {
		# This server doesn't like HEAD!
		@doc = `$linkcheckfull \"$check\"`;
		$head = 0;
		goto boo;
	    }
	    return "BAD";
	}
    }
    return "BAD";
}


sub GetLinks {
    my $in = $_[0];
    my @result;

  getlinkloop:
    while($in =~ /[^<]*(<[^>]+>)/g ) {
	# we have a tag in $1
	$tag = $1;
	
	if($tag =~ /^<!--/) {
	    # this is a comment tag, ignore it 
	}
	else {
	    if($tag =~ /(src|href|background|archive) *= *(\"[^\"]\"|[^ )>]*)/i) {
   	        $url=$2;
		if($url =~ /^\"(.*)\"$/) {
		    # this was a "string" now $1 has removed the quotes:
		    $url=$1;
		}


		$url =~ s/([^\#]*)\#.*/$1/g;

		if($url eq "") {
		    # if the link was nothing than a #-link it may now have
		    # been emptied completely so then we skip the rest
		    next getlinkloop;		    
		}

		if($done{$url}) {
		    # if this url already is done, do next
		    $done{$url}++;
		    next getlinkloop;
		}

		$done{$url} = 1; # this is "done"

	        push @result, $url;
		if($tag =~ /< *([^ ]+)/) {
#		    print "TAG: $1\n";
		    $tagtype{$url}=$1;
		}
	    }
        }
    }
    return @result;
}

@links = &GetLinks($in);

 linkloop:
for(@links) {
    $url = $_;

    if($url =~ /^([^:]+):/) {
	$prot = $1;
#	if($prot !~ /(http|ftp|gopher)/i) {
	if($prot !~ /http/i) {
	    # this is an unsupported protocol, we ignore this
	    next linkloop;
	}
	$link = $url;
    }
    else {
	if($external) {
	    next linkloop;
	}

	# this is a link on the save server:
	if($url =~ /^\//) {
	    # from root
	    $link = "$getprotocol://$getserver$url";
	}
	else {
	    # from the scanned page's dir
	    $nyurl=$url;

	    if(length($getpath) &&
	       ($getpath !~ /\/$/) &&
	       ($nyurl !~ /^\//)) {
		# lacks ending slash, add one to the document part:
		$nyurl = "/".$nyurl;
	    }
	    $link = "$getprotocol://$getserver/$getpath$nyurl";
	}
    }

#print "test $link\n";
#$success = "GOOD";

    $success = &LinkWorks($link);

    $count = $done{$url};

    $allcount += $count;

    print "$success $count <".$tagtype{$url}."> $link $url\n";

# If bad and -l, present the line numbers of the usage
    if("BAD" eq $success) {
	$badlinks++;
	if($linenumber) {
	    $line =1;
	    for(@indoc) {
		if($_ =~ /$url/) {
		    print " line $line\n";
		}
		$line++;
	    }
	}
    }

}

if($verbose) {
    print "$allcount links were checked";
    if($badlinks > 0) {
	print ", $badlinks were found bad";
    }
    print "\n";
}