├── README.md
├── redirect.php
└── screenshot.png


/README.md:
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 1 | # wp-debug-redirect
 2 | Allows you to debug mysterious page redirects
 3 | 
 4 | # How to use it
 5 | Simply install and activate the plugin.
 6 | 
 7 | From now on all page redirects that were initiated by WordPress will include some additonal HTTP headers with a stack-trace that triggered the redirect.
 8 | 
 9 | ![Screenshot](/screenshot.png?raw=true "Example of debug headers for a WP redirect")
10 | 


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/redirect.php:
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  1 | <?php
  2 | /**
  3 |  * Plugin Name: Debug - WP Redirect
  4 |  * Description: Adds debugging output to the HTTP header response to find out which file/function triggered a redirect.
  5 |  * Author:      Philipp Stracker
  6 |  * Author URI:  http://www.stracker.net/
  7 |  * Created:     15.09.2015
  8 |  * Version:     1.0.0
  9 |  *
 10 |  * Simply activate the plugin and it will add debugging information to all
 11 |  * WordPress redirects.
 12 |  *
 13 |  * Inspect the HTTP response in your browsers developer console to see the
 14 |  * debug information.
 15 |  * ----------------------------------------------------------------------------
 16 |  */
 17 | 
 18 | class WDevDebug_Redirect {
 19 | 
 20 | 	/**
 21 | 	 * Returns the singleton instance.
 22 | 	 *
 23 | 	 * @since  1.0.0
 24 | 	 * @return WDevDebug_Redirect
 25 | 	 */
 26 | 	static public function instance() {
 27 | 		static $Inst = null;
 28 | 
 29 | 		if ( null === $Inst ) {
 30 | 			$Inst = new WDevDebug_Redirect();
 31 | 		}
 32 | 
 33 | 		return $Inst;
 34 | 	}
 35 | 
 36 | 	/**
 37 | 	 * Constructor.
 38 | 	 * Hooks up this module.
 39 | 	 *
 40 | 	 * @since  1.0.0
 41 | 	 */
 42 | 	protected function __construct() {
 43 | 		add_filter(
 44 | 			'wp_redirect',
 45 | 			array( $this, 'redirect_headers' ),
 46 | 			9999
 47 | 		);
 48 | 	}
 49 | 
 50 | 	/**
 51 | 	 * Adds some redirect headers with debugging information to the response.
 52 | 	 *
 53 | 	 * @since  1.0.0
 54 | 	 */
 55 | 	public function redirect_headers( $location ) {
 56 | 		if ( $location ) {
 57 | 			$trace = $this->get_trace();
 58 | 
 59 | 			if ( ! headers_sent() ) {
 60 | 				foreach ( $trace as $ind => $line ) {
 61 | 					header( "WPDev-Redirect-Trace-$ind: $line", false );
 62 | 				}
 63 | 			} else {
 64 | 				echo "\n";
 65 | 				foreach ( $trace as $ind => $line ) {
 66 | 					echo "<!-- wdpu-redirect-trace-$ind: $line -->\n";
 67 | 				}
 68 | 			}
 69 | 		}
 70 | 
 71 | 		return $location;
 72 | 	}
 73 | 
 74 | 	/**
 75 | 	 * Generates an array of stack-trace information. Each array item is a
 76 | 	 * simple string that can be directly output.
 77 | 	 *
 78 | 	 * @since  1.0.0
 79 | 	 * @return array Trace information
 80 | 	 */
 81 | 	public function get_trace() {
 82 | 		$result = array();
 83 | 
 84 | 		$trace = debug_backtrace();
 85 | 		$trace_count = count( $trace );
 86 | 		$_num = 0;
 87 | 		$start_at = 0;
 88 | 
 89 | 		// Skip the first 4 trace lines (filter call inside wp_redirect)
 90 | 		if ( $trace_count > 4 ) { $start_at = 4; }
 91 | 
 92 | 		for ( $i = $start_at; $i < $trace_count; $i += 1 ) {
 93 | 			$trace_info = $trace[$i];
 94 | 			$line_info = $trace_info;
 95 | 			$j = $i;
 96 | 
 97 | 			while ( empty( $line_info['line'] ) && $j < $trace_count ) {
 98 | 				$line_info = $trace[$j];
 99 | 				$j += 1;
100 | 			}
101 | 
102 | 			$_file = empty( $line_info['file'] ) ? '' : $line_info['file'];
103 | 			$_line = empty( $line_info['line'] ) ? '' : $line_info['line'];
104 | 			$_args = empty( $trace_info['args'] ) ? array() : $trace_info['args'];
105 | 			$_class = empty( $trace_info['class'] ) ? '' : $trace_info['class'];
106 | 			$_type = empty( $trace_info['type'] ) ? '' : $trace_info['type'];
107 | 			$_function = empty( $trace_info['function'] ) ? '' : $trace_info['function'];
108 | 
109 | 			$_num += 1;
110 | 			$_arg_string = '';
111 | 			$_args_arr = array();
112 | 
113 | 			if ( $i > 0 && is_array( $_args ) && count( $_args ) ) {
114 | 				foreach ( $_args as $arg ) {
115 | 					if ( is_scalar( $arg ) ) {
116 | 						if ( is_bool( $arg ) ) {
117 | 							$_args_arr[] = ( $arg ? 'true' : 'false' );
118 | 						} elseif ( is_string( $arg ) ) {
119 | 							$_args_arr[] = '"' . $arg . '"';
120 | 						} else {
121 | 							$_args_arr[] = $arg;
122 | 						}
123 | 					} elseif ( is_array( $arg ) ) {
124 | 						$_args_arr[] = '[Array]';
125 | 					} elseif ( is_object( $arg ) ) {
126 | 						$_args_arr[] = '[' . get_class( $arg ) . ']';
127 | 					} elseif ( is_null( $arg ) ) {
128 | 						$_args_arr[] = 'NULL';
129 | 					} else {
130 | 						$_args_arr[] = '[?]';
131 | 					}
132 | 				}
133 | 
134 | 				$_arg_string = implode( ',', $_args_arr );
135 | 			}
136 | 
137 | 			if ( strlen( $_file ) > 80 ) {
138 | 				$_file = '...' . substr( $_file, -77 );
139 | 			} else {
140 | 				$_file = str_pad( $_file, 80, ' ', STR_PAD_RIGHT );
141 | 			}
142 | 
143 | 			$result_item = sprintf(
144 | 				'%s:%s %s(%s)',
145 | 				$_file,
146 | 				str_pad( $_line, 5, ' ', STR_PAD_LEFT ),
147 | 				$_class . $_type . $_function,
148 | 				$_arg_string
149 | 			);
150 | 
151 | 			$_num_str = str_pad( $_num, 2, '0', STR_PAD_LEFT );
152 | 			$result[$_num_str] = $result_item;
153 | 		}
154 | 
155 | 		return $result;
156 | 	}
157 | 
158 | }
159 | WDevDebug_Redirect::instance();


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/screenshot.png:
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https://raw.githubusercontent.com/stracker-phil/wp-debug-redirect/12758fe92737284a581c68517a031d861e7d6aab/screenshot.png


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