Beginning Web Development With Perl : From Novice to ... - Nabo

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CHAPTER 2 ■ POPULAR CGI MODULES 41print header,start_html("Making URLs Safe Is Our Business"),p("The string that is unsafe for a URL is: $unsafestring\n"),p("When fed through the url_escape() function it becomes:$safestring\n"),end_html;exit;The code is pretty simple but illustrates the uri_escape() function very well. As usual, theURI::Escape functions are imported into the namespace with this code:use URI::Escape;From there, a string is created with all sorts of unsafe characters, including a $, brackets,and spaces. Notice the \ included in the string. The backslash doesn’t actually appear in theoutput, since it’s used to escape the $5, so that Perl doesn’t interpret the $5 as a variable!my $unsafestring = "\$5/[3454]/this is a windows filename.asp";The string is then run through the uri_escape() function, with the results placed intoa variable called $safestring:my $safestring = uri_escape($unsafestring);The next lines of code in the example are ones that you’ve seen in earlier examples, beginningthe web page output and so on. Two lines of output to the resulting web page are basedon the output from the uri_escape() function:p("The string that is unsafe for a URL is: $unsafestring\n"),p("When fed through the url_escape() function it becomes: $safestring\n"),First, you’re shown the string as it would appear before any escaping of unsafe characters(the variable $unsafestring). Next, the result of the uri_escape function is shown as the contentsof the $safestring variable. Viewing the page through a browser, as shown in Figure 2-3,illustrates the results of the program.Parsing an escaped URI string is a useful task, not only when programming for the Web,but also when performing forensics or monitoring security logs. Attackers and malicious codewill frequently disguise their code by escaping it using the hex equivalent. Feeding that encodedstring into the uri_unescape() function can help reveal the intent of such an attack. Listing 2-5shows an example of using uri_escape().
42CHAPTER 2 ■ POPULAR CGI MODULESFigure 2-3. An escaped string viewed through a web browserListing 2-5. Using uri_unescape to Make a String Without Escape Characters#!/usr/bin/perl -Tuse strict;use URI::Escape;use CGI qw/:standard/;my $unsafestring = "\$5/[3454]/this is a windows filename.asp";my $safestring = uri_escape($unsafestring);my $unescstring = uri_unescape($safestring);print header,start_html("Making URLs Safe Is Our Business"),p("The string that is unsafe for a URL is: $unsafestring\n"),p("When fed through the url_escape() function it becomes: $safestring\n"),p("When the escaped string is unescaped, it becomes: $unescstring\n"),end_html;exit;
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Beginning Web Development with Perl
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PART 5 ■ ■ ■ Creating Web Tem
Page 8 and 9: ■CONTENTSvii■CHAPTER 4 System I
Page 10 and 11: ■CONTENTSixCreating a SOAP Listen
Page 12 and 13: ■CONTENTSxiTemplate Toolkit Synta
Page 14 and 15: About the Author■STEVE SUEHRING i
Page 16 and 17: AcknowledgmentsThanks to James Lee
Page 18 and 19: xx■INTRODUCTIONThis book will use
Page 20 and 21: CHAPTER 1■ ■ ■The CGI ModuleT
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Page 66 and 67: 50CHAPTER 3 ■ DATABASES AND PERLT
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Page 104 and 105: CHAPTER 5■ ■ ■LWP ModulesLWP
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CHAPTER 5 ■ LWP MODULES 93Get Fun
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CHAPTER 5 ■ LWP MODULES 97These a
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CHAPTER 5 ■ LWP MODULES 99Recall
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CHAPTER 5 ■ LWP MODULES 101which
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108CHAPTER 6 ■ NET:: TOOLSCreatin
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110CHAPTER 6 ■ NET:: TOOLSThe out
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112CHAPTER 6 ■ NET:: TOOLSmy $pop
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114CHAPTER 6 ■ NET:: TOOLSthe POP
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116CHAPTER 6 ■ NET:: TOOLS($messa
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118CHAPTER 6 ■ NET:: TOOLSListing
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120CHAPTER 6 ■ NET:: TOOLSFor the
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122CHAPTER 6 ■ NET:: TOOLSNet::SM
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124CHAPTER 6 ■ NET:: TOOLS$smtpco
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126CHAPTER 6 ■ NET:: TOOLSuse Net
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128CHAPTER 6 ■ NET:: TOOLSListing
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130CHAPTER 6 ■ NET:: TOOLSFor exa
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132CHAPTER 6 ■ NET:: TOOLSSending
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PART 3■ ■ ■XML and RSS
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138CHAPTER 7 ■ SOAP-BASED WEB SER
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154CHAPTER 8 ■ PERL AND RSSFigure
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156CHAPTER 8 ■ PERL AND RSShttp:/
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158CHAPTER 8 ■ PERL AND RSSDebugg
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160CHAPTER 8 ■ PERL AND RSS$rsswr
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162CHAPTER 8 ■ PERL AND RSSListin
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CHAPTER 9■ ■ ■XML Parsing wit
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CHAPTER 9 ■ XML PARSING WITH PERL
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PART 4■ ■ ■PerformanceEnhance
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184CHAPTER 10 ■ APACHE AND MOD_PE
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202CHAPTER 11 ■ DEVELOPMENT WITH
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CHAPTER 12■ ■ ■The Template T
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CHAPTER 12 ■ THE TEMPLATE TOOLKIT
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CHAPTER 13■ ■ ■Perl Web Sites
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CHAPTER 13 ■ PERL WEB SITES WITH
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284APPENDIX ■ PERL BASICSKeywords
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286APPENDIX ■ PERL BASICS$ perl n
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288APPENDIX ■ PERL BASICSAnd line
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290APPENDIX ■ PERL BASICSCan you
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292APPENDIX ■ PERL BASICSBy defau
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294APPENDIX ■ PERL BASICS#!/usr/b
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296APPENDIX ■ PERL BASICSThe last
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298APPENDIX ■ PERL BASICSThe NOT
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300APPENDIX ■ PERL BASICSprint "S
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302APPENDIX ■ PERL BASICSthe syst
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304APPENDIX ■ PERL BASICS$ perl s
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306APPENDIX ■ PERL BASICSThis cod
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308APPENDIX ■ PERL BASICS$a = 6 *
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310APPENDIX ■ PERL BASICS$a = "A9
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312APPENDIX ■ PERL BASICS#!/usr/b
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314APPENDIX ■ PERL BASICSmy $name
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316APPENDIX ■ PERL BASICSis short
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318APPENDIX ■ PERL BASICSLet’s
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320APPENDIX ■ PERL BASICSOther Te
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322APPENDIX ■ PERL BASICS}}}actio
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324APPENDIX ■ PERL BASICSNotice t
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326APPENDIX ■ PERL BASICSLooping
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328APPENDIX ■ PERL BASICSuse stri
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330APPENDIX ■ PERL BASICSuntil ($
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332APPENDIX ■ PERL BASICSuse stri
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334APPENDIX ■ PERL BASICSdoneAll
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336APPENDIX ■ PERL BASICS$ perl r
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338APPENDIX ■ PERL BASICSSummaryT
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340■INDEXmethods for retrieving r
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342■INDEXdo() method for, 62dumpi
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344■INDEXhello option for Net::SM
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346■INDEXNet::DNS module, 125-128
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348■INDEXrecord with Net::DNS mod
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350■INDEXstoring mail server in e
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352■INDEXlogging based on, 229pri
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