106 P l u g - i n P H P : 1 0 0 P o w e r S o l u t i o n s 106 P l u g - i n P H P : 1 0 0 P o w e r S o l u t i o n s How It Works The first thing this plug-in does is make a note of the current visitor’s IP address, which is a four-part number that directly identifies that user, and looks something like 208.77.188.166. Then, because IP addresses can be shared, for example across a business or home network, the browser’s User Agent string is also noted. This is a string that identifies the type and version of a browser and varies widely in use but may look something like “Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Media Center PC 6.0)”. These two strings are then combined and placed in the string variable $data, followed by a \n newline character. Next a switch statement with four sections is entered. The first section is processed if $action is set to reset. It opens the file $filename for writing, using an argument of “w”, and then calls the function flock(). This is PHP’s file locking mechanism and what this call does is request an exclusive lock on the file by passing the argument LOCK_EX. The function waits until any and all other processes have finished using the file and then releases the lock using flock() with an argument of LOCK_UN, and closes the file. This has the effect of truncating the file to zero bytes. Had a lock not been set (and the program not waited its turn), if two requests came through at the same time, one to append to the file, and this one to truncate it, there would be no way of knowing which process might “win.” This way, all accesses to the file are queued up and all processes take their turn. The second section is executed if $action is set to add. Here the file is opened in a similar way to the previous example, except that the argument “a+” is used, which stands for append to. Again the flock() function is called, and when control over the file is gained, the data in $data is appended to the file, the lock is released, and the file closed. The third section is executed if $action is set to get, in which case the file is opened just for reading using an argument of “r”. Then, flock() is called, and after control is gained, the fread() function is called to read the entire contents of $filename into $file, except for the final character which will be a \n newline, and is not needed. The file lock is then released and the file is closed. With the contents of the file now stored in the variable $file, it is extracted into the array $lines by using the explode() function, which splits the contents of $file at every \n linefeed character. Then, the number of elements is counted using count() and assigned to the variable $raw. To obtain the unique counts (the number of hits made by different IP/browser combinations, ignoring multiple hits by the same user), the array_unique() function is called before using count() and passing the result to $unique. Afterward, a two-element array containing these raw and unique values is returned. The final section is executed when $action is set to delete and simply uses the unlink() function to delete the file pointed to by $filename. How to Use It The way you will mostly use this plug-in is as follows: PIPHP_HitCounter("counter.txt", "add"); This code passes the filename counter.txt and the parameter “add” to the function PIPHP_HitCounter(), which then appends the IP address and User Agent of the current user to the file. It’s not necessary to first create the file because, if it doesn’t already exist, it will be created. C h a p t e r 5 : C o n t e n t M a n a g e m e n t 107 C h a p t e r 5 : C o n t e n t M a n a g e m e n t 107 Should you wish to reset the file data and start over, you can issue the following command, which truncates the data file back to zero bytes in length: PIPHP_HitCounter("counter.txt", "reset"); To delete the counter, use this command: PIPHP_HitCounter("counter.txt", "delete"); To instead get an instant hit count report, use code such as this: $result = PIPHP_HitCounter("counter.txt", "get"); echo "Raw: $result[0] / Unique: $result[1]"; You can give the counter any name you like, but if you use the .txt extension, as in these examples, you’ll be able to load it into a text editor and browse through it. The Plug-in function PIPHP_HitCounter($filename, $action) { $data = getenv("REMOTE_ADDR") . getenv("HTTP_USER_AGENT") . "\n"; switch ($action) { case "reset": $fp = fopen($filename, "w"); if (flock($fp, LOCK_EX)) ; flock($fp, LOCK_UN); fclose($fp); return; case "add": $fp = fopen($filename, "a+"); if (flock($fp, LOCK_EX)) fwrite($fp, $data); flock($fp, LOCK_UN); fclose($fp); return; case "get": $fp = fopen($filename, "r"); if (flock($fp, LOCK_EX)) $file = fread($fp, filesize($filename) - 1); flock($fp, LOCK_UN); fclose($fp); $lines = explode("\n", $file); $raw = count($lines); $unique = count(array_unique($lines)); return array($raw, $unique); case "delete": unlink($filename); return; } } 108 P l u g - i n P H P : 1 0 0 P o w e r S o l u t i o n s 108 P l u g - i n P H P : 1 0 0 P o w e r S o l u t i o n s Referer Log In a similar way to being able to instantly track visitor hits, this plug-in keeps constant track of the URLs from which your users are being sent. Again, this is something you can track with a service such as Google Analytics, or by processing your log files, but neither of these methods is as quick and easy to use as this plug-in for providing instant data, as shown in Figure 5-10. About the Plug-in This plug-in takes the name of a file to hold the referring data for the current page, as well as details on what to do with it. Upon success, it either updates or returns details fr om the data file. It accepts these arguments: • $filename A path/file name to use for storing referring page data • $action What to do with the data: reset = reset all data; add = add the current visit to the data; get = retrieve referrer stats; delete = delete the file Variables, Arrays, and Functions $data String containing the referring page URL $fp File pointer to the referrer file $file String containing the contents of $filename $temp Temporary array containing unique referring URLs How It Works The first thing this plug-in does is make a note of the referring page’s URL, if there is one, placing it in $date, followed by a \n newline character. If no referring page was passed to the current program, perhaps because the URL was typed in directly, then $data is assigned the string “No Referrer”, followed by a \n newline. Next a switch statement with four sections is entered. The first section is processed if $action is set to reset. It opens the file $filename for writing, using an argument of “w”, and then calls the function flock(). The function waits until all other processes have finished using the file and then releases the lock and closes the file, truncating it to zero bytes. FIGURE 5-10 Keeping track of pages referring to your site is easy using this plug-in. 30 C h a p t e r 5 : C o n t e n t M a n a g e m e n t 109 C h a p t e r 5 : C o n t e n t M a n a g e m e n t 109 The second section is executed if $action is set to add. Here the argument “a+” is used to open the file for appending. Again the flock() function is called, and when control over the file is gained, the data in $data is appended to the file, the lock is released, and the file is closed. The third section is executed if $action is set to get, in which case the file is opened for reading using an argument of “r”. Then flock() is called, and after control is gained, the fread() function is called to read the entire contents of $filename into $file, excepting the final character which will be a \n newline character, and is therefore not needed. The file lock is then released and the file is closed. With the contents of the file now stored in the variable $file, the explode() function is used to extract this contents into the array $temp, splitting it at every \n linefeed character. All non-unique entries are then removed from the array, which is sorted to remove the gaps, and the resulting array is returned. The final section is executed when $action is set to delete and simply uses the unlink() function to delete the file pointed to by $filename. How to Use It You will normally call the plug-in with code such as the following, which creates the file refer.log if it doesn’t already exist, and writes the contents of $data to it. If the file does exist, the data is appended to it: PIPHP_RefererLog("refer.log", "add"); To delete this log file, use this command: PIPHP_RefererLog("refer.log", "delete"); Or to reset the log file by truncating it back to zero length, use: PIPHP_RefererLog("refer.log", "reset"); To display all the entries in the log file, you could use code such as the following, which uses a for loop to iterate through all the entries in the returned array and display them: $result = PIPHP_RefererLog("refer.log", "get"); for ($j = 0 ; $j < count($result) ; ++$j) echo "$result[$j]<br />"; The Plug-in function PIPHP_RefererLog($filename, $action) { $data = getenv("HTTP_REFERER") . "\n"; if ($data == "\n") $data = " No Referrer\n"; switch ($action) { case "reset": $fp = fopen($filename, "w"); if (flock($fp, LOCK_EX)) ; 110 P l u g - i n P H P : 1 0 0 P o w e r S o l u t i o n s flock($fp, LOCK_UN); fclose($fp); return; case "add": $fp = fopen($filename, "a+"); if (flock($fp, LOCK_EX)) fwrite($fp, $data); flock($fp, LOCK_UN); fclose($fp); return; case "get": $fp = fopen($filename, "r"); if (flock($fp, LOCK_EX)) $file = fread($fp, filesize($filename) -1); flock($fp, LOCK_UN); fclose($fp); $temp = array_unique(explode("\n", $file)); sort($temp); return $temp; case "delete": unlink($filename); return; } } . Functions $data String containing the referring page URL $fp File pointer to the referrer file $file String containing the contents of $filename $temp Temporary array containing unique referring URLs How. processing your log files, but neither of these methods is as quick and easy to use as this plug- in for providing instant data, as shown in Figure 5-10. About the Plug- in This plug- in takes. s Referer Log In a similar way to being able to instantly track visitor hits, this plug- in keeps constant track of the URLs from which your users are being sent. Again, this is something you can