1 files changed, 62 insertions, 0 deletions
diff --git a/021/ch2.pl b/021/ch2.pl
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+++ b/021/ch2.pl
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+#!/usr/bin/env perl
+#
+# Write a script for URL normalization based on rfc3986
+#
+# According to Wikipedia, URL normalization is the process by which URLs are
+# modified and standardized in a consistent manner. The goal of the
+# normalization process is to transform a URL into a normalized URL so it is
+# possible to determine if two syntactically different URLs may be equivalent.
+#
+# (https://en.wikipedia.org/wiki/URL_normalization).
+################################################################################
+
+use strict;
+use warnings;
+
+my $url = shift or die "Usage: $0 <url>\n";
+
+my $scheme_re = qr<([hH][tT][tT][pP][sS]?)>;
+my $ipv4_re = qr<(?:[0-9]{1,3}\.){3}[0-9]{1,3}>;
+my $hostname_re = qr<[a-zA-Z0-9.\-]+>;
+my $host_re = qr<($ipv4_re|$hostname_re)>;
+my $port_re = qr<(?::([0-9]+))?>;
+my $rest_re = qr<([a-zA-Z0-9/\-._~\?=&%#]*)>;
+
+# Capitalizing letters in escape sequences
+$url =~ s<%[a-zA-Z0-9]{2}>< uc($&) >ge;
+
+sub decode_octet {
+    my $octet = shift;
+    my $hex = hex(substr($octet, 1, length($octet)));
+    if (grep /^$hex$/, map ord, 'a'..'z', 'A'..'Z', '0'..'9', qw<- . _ ~>) {
+        return chr($hex);
+    } else {
+        return $octet;
+    }
+}
+
+# Decoding percent-encoded octets of unreserved characters
+$url =~ s<%[a-zA-Z0-9]{2}>< decode_octet($&) >ge;
+
+my ($scheme, $host, $port, $path) = $url =~
+    m<^$scheme_re://$host_re$port_re$rest_re>;
+
+die "Unable to decode URI" unless $scheme and $host;
+
+# Converting the scheme and host to lower case
+$scheme = lc($scheme);
+$host = lc($host);
+
+# Removing the default port
+if (!$port || $scheme eq 'http' && $port == 80 || $scheme eq 'https' && $port == 443) {
+    $port = '';
+} else {
+    $port = ":$port";
+}
+
+# Removing dot-segments
+$path =~ s</\./|/\.$></>g; # Remove all '.'
+$path =~ s</[^/]+/\.\.><>g; # Remove instances of the pattern: '/x/..'
+$path =~ s<(\.\./)+><>g; # Remove all '..'s left at the beginning
+
+print "$scheme://$host$port$path\n";