1;;; cgi.el -- using Emacs for CGI scripting 2;;; 3;;; Author: Eric Marsden <emarsden@laas.fr> 4;;; Michael Olson <mwolson@gnu.org> (slight modifications) 5;;; Keywords: CGI web scripting slow 6;;; Version: 0.3 7;;; Time-stamp: <2001-08-24 emarsden> 8;;; Copyright: (C) 2000 Eric Marsden 9;;; Parts copyright (C) 2006 Free Software Foundation, Inc. 10;; 11;; This program is free software; you can redistribute it and/or 12;; modify it under the terms of the GNU General Public License as 13;; published by the Free Software Foundation; either version 3 of 14;; the License, or (at your option) any later version. 15;; 16;; This program is distributed in the hope that it will be useful, 17;; but WITHOUT ANY WARRANTY; without even the implied warranty of 18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19;; GNU General Public License for more details. 20;; 21;; You should have received a copy of the GNU General Public 22;; License along with this program; if not, write to the Free 23;; Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, 24;; MA 02111-1307, USA. 25;; 26;; 27;;; Commentary: 28;; 29;; People who like this sort of thing will find this the sort of 30;; thing they like. -- Abraham Lincoln 31;; 32;; 33;; Overview ========================================================== 34;; 35;; A simple library for the Common Gateway Interface for Emacs, 36;; allowing you to service requests for non static web pages in elisp. 37;; Provides routines for decoding arguments to GET- and POST-type CGI 38;; requests. 39;; 40;; Usage: place a shell script such as the following in your web 41;; server's CGI directory (typically called something like 42;; /var/www/cgi-bin/): 43;; 44;; ,------------------------------------------------------------------- 45;; | #!/bin/sh 46;; | 47;; | emacs -batch -l cgi.el -f cgi-calendar 48;; `------------------------------------------------------------------- 49;; 50;; (`cgi-calendar' is a sample elisp CGI script provided at the end of 51;; this file). 52;; 53;; Alternatively, if you're running version 2.x of the linux kernel 54;; you could make .elc files directly executable via the binfmt_misc 55;; mechanism and run them straight from the cgi-bin directory. 56;; 57;; Efficiency would be improved by having Emacs bind to the http 58;; service port and spawn a thread per connection. Extending Emacs to 59;; support server sockets and multithreading is left as an exercise 60;; for the reader. 61;; 62;; References: 63;; * rfc1738 "Uniform Resource Locators" 64;; * rfc1630 "Universal Resource Identifiers in WWW" 65;; 66;; Thanks to Christoph Conrad <christoph.conrad@gmx.de> for pointing 67;; out a bug in the URI-decoding. 68 69;;; Code: 70 71(eval-when-compile 72 (require 'cl) 73 (require 'calendar)) 74 75(defconst cgi-url-unreserved-chars '( 76 ?a ?b ?c ?d ?e ?f ?g ?h ?i ?j ?k ?l ?m 77 ?n ?o ?p ?q ?r ?s ?t ?u ?v ?w ?x ?y ?z 78 ?A ?B ?C ?D ?E ?F ?G ?H ?I ?J ?K ?L ?M 79 ?N ?O ?P ?Q ?R ?S ?T ?U ?V ?W ?X ?Y ?Z 80 ?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 81 ?\$ ?\- ?\_ ?\. ?\! ?\~ ?\* ?\' ?\( ?\) ?\,)) 82 83(defun cgi-int-char (i) 84 (if (fboundp 'int-char) (int-char i) i)) 85 86(defun cgi-hex-char-p (ch) 87 (declare (character ch)) 88 (let ((hexchars '(?0 ?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 89 ?A ?B ?C ?D ?E ?F))) 90 (member (upcase ch) hexchars))) 91 92;; decode %xx to the corresponding character and + to ' ' 93(defun cgi-decode-string (str) 94 (do ((i 0) 95 (len (length str)) 96 (decoded '())) 97 ((>= i len) (concat (nreverse decoded))) 98 (let ((ch (aref str i))) 99 (cond ((eq ?+ ch) 100 (push ?\ decoded) 101 (incf i)) 102 ((and (eq ?% ch) 103 (< (+ i 2) len) 104 (cgi-hex-char-p (aref str (+ i 1))) 105 (cgi-hex-char-p (aref str (+ i 2)))) 106 (let ((hex (string-to-number (substring str (+ i 1) (+ i 3)) 16))) 107 (push (cgi-int-char hex) decoded) 108 (incf i 3))) 109 (t (push ch decoded) 110 (incf i)))))) 111 112(defun cgi-position (item seq &optional start end) 113 (or start (setq start 0)) 114 (or end (setq end (length seq))) 115 (while (and (< start end) 116 (not (equal item (aref seq start)))) 117 (setq start (1+ start))) 118 (and (< start end) start)) 119 120;; Parse "foo=x&bar=y+re" into (("foo" . "x") ("bar" . "y re")) 121;; Substrings are plus-decoded and then URI-decoded. 122(defun cgi-decode (q) 123 (when q 124 (flet ((split-= (str) 125 (let ((pos (or (cgi-position ?= str) 0))) 126 (cons (cgi-decode-string (substring str 0 pos)) 127 (cgi-decode-string (substring str (+ pos 1))))))) 128 (mapcar #'split-= (split-string q "&"))))) 129 130(defun cgi-lose (fmt &rest args) 131 (let ((why (apply #'format fmt args))) 132 (message "Script error: %s" why) ; to error_log 133 (princ "Content-type: text/html\n\n") ; to browser 134 (princ "<html><head><title>Script error</title></head>\r\n") 135 (princ "<body><h1>Script error</h1>\r\n<p>\r\n") 136 (princ why) 137 (princ "\r\n</body></html>\r\n") 138 (kill-emacs 0))) 139 140(defmacro cgi-evaluate (&rest forms) 141 `(condition-case why 142 (princ (with-output-to-string ,@forms)) 143 (error (cgi-lose "Emacs Lisp error: %s" why)))) 144 145(defun cgi-arguments () 146 (let ((method (getenv "REQUEST_METHOD")) 147 req buf) 148 (cond ((null method) 149 (cgi-lose "No request method specified")) 150 ((string= "GET" method) 151 (unless (getenv "QUERY_STRING") 152 (cgi-lose "No query string for GET request")) 153 (cgi-decode (getenv "QUERY_STRING"))) 154 ((string= "POST" method) 155 (setq req (getenv "CONTENT_LENGTH")) 156 (unless req 157 (cgi-lose "No content-length for POST request")) 158 (setq buf (get-buffer-create " *cgi*")) 159 (set-buffer buf) 160 (erase-buffer) 161 (loop for i from 1 to (string-to-number req) 162 do (insert (read-event))) 163 (cgi-decode (buffer-string))) 164 (t 165 (cgi-lose "Can't handle request method %s" method))))) 166 167;; ==================================================================== 168;; a sample application: calendar via the web. If invoked without 169;; arguments, presents a calendar for the three months around the 170;; current date. You can request a calendar for a specific period by 171;; specifying the year and the month in the query string: 172;; 173;; ~$ lynx -dump 'http://localhost/cgi-bin/cal?year=1975&month=6' 174;; 175;; When run in batch mode, text normally displayed in the echo area 176;; (via `princ' for example) goes to stdout, and thus to the browser. 177;; Text output using `message' goes to stderr, and thus normally to 178;; your web server's error_log. 179;; ==================================================================== 180 181(eval-and-compile 182 (if (fboundp 'calendar-extract-month) 183 (defalias 'cgi-calendar-extract-month 'calendar-extract-month) 184 (defalias 'cgi-calendar-extract-month 'extract-calendar-month)) 185 186 (if (fboundp 'calendar-extract-year) 187 (defalias 'cgi-calendar-extract-year 'calendar-extract-year) 188 (defalias 'cgi-calendar-extract-year 'extract-calendar-year)) 189 190 (if (fboundp 'calendar-generate) 191 (defalias 'cgi-calendar-generate 'calendar-generate) 192 (defalias 'cgi-calendar-generate 'generate-calendar))) 193 194(defun cgi-calendar-string () 195 (require 'calendar) 196 (let* ((args (cgi-arguments)) 197 (now (calendar-current-date)) 198 (mnth (cdr (assoc "month" args))) 199 (month (if mnth (string-to-number mnth) 200 (cgi-calendar-extract-month now))) 201 (yr (cdr (assoc "year" args))) 202 (year (if yr (string-to-number yr) 203 (cgi-calendar-extract-year now)))) 204 (with-temp-buffer 205 (cgi-calendar-generate month year) 206 (buffer-string)))) 207 208(defun cgi-calendar () 209 (cgi-evaluate 210 (princ "Content-type: text/html\n\n") 211 (princ "<html><head><title>Emacs calendar</title></head>\r\n") 212 (princ "<body> <h1>Emacs calendar</h1>\r\n") 213 (princ "<pre>\r\n") 214 (princ (cgi-calendar-string)) 215 (princ "\r\n</pre></body></html>\r\n"))) 216 217(provide 'cgi) 218 219;; cgi.el ends here 220