1 ;;; Scratchy gopher server
17 (chicken process-context)
18 (chicken process-context posix)
19 srfi-1 srfi-13 matchable)
23 (define scratchy-version "1.3.0")
25 (define scratchy-footer
27 "--------------------------------------------------\n"
28 "This gopher hole was dug using Scratchy v" scratchy-version ".\n"
29 "Powered by Chicken Scheme!"))
31 (define gopher-index-filename "index")
35 ;; We don't yet use worker threads here to handle requests,
36 ;; the server just blocks until the first request is finished.
37 ;; While we should fix this, it's actually probably okay, as
38 ;; we genuinely don't expect a huge flood of gopher traffic. :-(
41 root-dir host port display-footer user group blacklist blacklist-resp)
43 (define (run-server config)
44 ;; (set-buffering-mode! (current-output-port) #:line)
45 (let ((listener (tcp-listen (config-port config) 10 "::")))
46 (print "Gopher server listening on port " (config-port config) " ...")
48 (server-loop listener config))
51 (define (drop-privs config)
52 (let ((uid (config-user config))
53 (gid (config-group config)))
54 (if (not (null? gid)) ; Group first, since only root can switch groups.
55 (set! (current-group-id) gid))
57 (set! (current-user-id) uid))))
59 (define (server-loop listener config)
60 (let-values (((in-port out-port) (tcp-accept listener)))
61 (let-values (((local-ip remote-ip) (tcp-addresses in-port)))
62 (print "Accepted connection from " remote-ip
63 " on " (seconds->string))
65 (if (or (null? (config-blacklist config))
66 (not (member remote-ip
68 (config-blacklist config)
70 (let* ((line (read-line in-port))
71 (selector-raw (string-trim-both line))
72 (selector (if (= (string-length selector-raw) 0)
77 (with-output-to-port out-port
79 (serve-selector selector config)))
80 (print "... served selector '" selector "'. Closing connection."))
82 (print-error-message o out-port)
83 (print-error-message o)
84 (print "Error while attempting to serve selector " selector "."))))
86 (print "Connection from blacklisted IP. Closing.")
87 (with-output-to-port out-port
89 (print* "Refusing to serve to IP " remote-ip ".\r\n")
90 (unless (null? (config-blacklist-resp config))
91 (for-each (lambda (l) (print* l "\r\n"))
93 (config-blacklist-resp config)
97 (print-error-message o))))
98 (close-input-port in-port)
99 (close-output-port out-port))
100 (server-loop listener config))
102 ;;; Selector type inference
104 (define (true-for-one? predicate values)
107 (if (predicate (car values))
109 (true-for-one? predicate (cdr values)))))
111 (define (has-suffix? selector . suffixes)
112 (true-for-one? (lambda (suffix)
113 (string-suffix? suffix selector))
116 (define (has-prefix? selector . prefixes)
117 (true-for-one? (lambda (prefix)
118 (string-prefix? prefix selector))
121 (define (infer-selector-type selector)
122 (let ((l (string-downcase selector)))
124 ((or (= (string-length l) 0)
125 (string-suffix? "/" l)) 1)
126 ((has-suffix? l ".txt" ".org" ".md") 0)
127 ((has-suffix? l ".png" ".jpg" ".gif" ".bmp" ".tif" ".tga") 'I)
128 ((has-suffix? l "?" "%3f") 7)
129 ((has-prefix? l "url:" "/url:") 'h)
133 ;;; Selector retrieval
135 (define (serve-selector raw-selector config)
136 (let* ((selector-list (string-split raw-selector "\t"))
137 (selector (car selector-list))
138 (arguments (cdr selector-list)))
139 (if (string-contains selector "|")
140 (let ((l (string-split selector "|" #t)))
141 (serve-script (car l) (cdr l) config))
142 (case (infer-selector-type selector)
143 ((1) (serve-directory-file selector config))
144 ((7) (let ((l (string-split selector "?" #t)))
145 (serve-script (car l) arguments config)))
146 ((0) (serve-text-file selector config))
147 ((h) (serve-url selector config))
148 (else (serve-binary-file selector config))))))
150 (define (legal-filename? filename config)
151 (and (string-prefix? (config-root-dir config)
152 (normalize-pathname filename))
153 (file-exists? filename)
154 (not (directory-exists? filename))
155 (file-readable? filename)))
157 (define (legal-script-filename? filename config)
158 (and (legal-filename? filename config)
159 (string-suffix? ".scm" filename)
160 (file-executable? filename)))
162 (define (serve-directory-file selector config)
163 (let ((filename (make-pathname (list (config-root-dir config) selector)
164 gopher-index-filename)))
165 (if (legal-filename? filename config)
167 (with-input-from-file filename
169 (let loop ((c (peek-char)))
176 (serve-record (read) selector config)
178 (serve-info-records (read-line)))
179 (loop (peek-char)))))))
180 (if (config-display-footer config)
181 (serve-info-records scratchy-footer))
183 (error "No legal index file not found."))))
185 (define (serve-text-file selector config)
186 (let ((filename (make-pathname (config-root-dir config) selector)))
187 (if (legal-filename? filename config)
189 (with-input-from-file filename
196 (error "File not found." filename))))
198 (define (serve-binary-file selector config)
199 (let ((filename (make-pathname (config-root-dir config) selector)))
200 (if (legal-filename? filename config)
201 (with-input-from-file filename
203 (let loop ((b (read-byte)))
208 (loop (read-byte)))))))
209 (error "File not found." filename))))
211 (define (serve-url selector config)
212 (let ((url (substring selector 4)))
214 "<html><head><title>Redirection</title>"
215 "<meta http-equiv=\"refresh\" content=\"10; URL='" url "'\" />"
217 "<p>If you are seeing this page, your gopher browser does not "
218 "properly support URL directory entries or cannot follow such "
220 "<p>If you are viewing this page using a web browser, you should "
221 "be redirected shortly. Otherwise, you can manually open the "
222 "the follwing url:\n"
224 "<a href=\"" url "\">" url "</a>\n"
227 (define (serve-script selector arguments config)
228 (let ((filename (make-pathname (config-root-dir config) selector)))
229 (if (legal-script-filename? filename config)
230 (let* ((sexp (with-input-from-file filename read))
231 (script-result (with-selector-dir
234 (apply (eval sexp) arguments)))))
235 (when (pair? script-result)
236 (serve-records script-result
237 (pathname-directory selector) config)
239 (error "No legal index script not found." filename))))
244 (define (serve-records records dir-selector config)
247 (serve-record record dir-selector config))
250 (define (serve-info-records string)
254 (for-each (lambda (char)
255 (print* (if (eq? char #\tab)
259 (print "\tfake\tfake\t1\r"))
260 (string-split string "\n" #t)))
262 (define (serve-record record dir-selector config)
264 ((? string?) (serve-info-records record))
265 (('shell command) (serve-shell-command command dir-selector config))
266 (('eval expression) (serve-expression expression dir-selector config))
267 (('url display-string url)
268 (print #\h display-string "\tURL:" url
269 "\t" (config-host config)
270 "\t" (config-port config) "\r"))
271 ((type display-string selector host port)
272 (print type display-string "\t" selector "\t" host "\t" port "\r"))
273 ((type display-string selector host)
274 (serve-record (list type display-string selector host 70)
275 dir-selector config))
276 ((type display-string selector)
277 (serve-record (list type display-string
278 (make-pathname dir-selector selector)
279 (config-host config) (config-port config))
280 dir-selector config))
281 ((display-string selector)
282 (serve-record (list (infer-selector-type selector) display-string selector)
283 dir-selector config))
285 (serve-record (list (infer-selector-type selector) selector)
286 dir-selector config))
287 (else (error "Unknown record type."))))
289 (define (serve-shell-command command dir-selector config)
293 (let-values (((in-port out-port id) (process command)))
294 (let ((string (read-string #f in-port)))
295 (if (and (not (eof-object? string))
296 (> (string-length string) 0))
297 (serve-info-records (string-chomp string "\n")))
298 (close-input-port in-port)
299 (close-output-port out-port))))))
301 (define (serve-expression expression dir-selector config)
305 (serve-records (eval expression) dir-selector config))))
310 (define (with-current-working-directory directory thunk)
311 (let ((old-wd (current-directory))
315 (change-directory directory)
316 (set! result (thunk))
317 (change-directory old-wd)
320 (change-directory old-wd)
323 (define (with-selector-dir selector config thunk)
324 (with-current-working-directory
325 (make-pathname (config-root-dir config)
326 (pathname-directory selector)) thunk))
331 (define (print-usage progname)
332 (let ((indent-str (make-string (string-length progname) #\space)))
334 progname " -h/--help\n"
335 progname " [-n/--no-footer] [-u/--user UID] [-g/--group GID]\n"
336 indent-str " [-b/--blacklist FILE] [-r/--blacklist-resp RESPFILE] root-dir hostname [port]\n"
338 "The -n option tells the server to not display a directory footer.\n"
339 "The -u and -g can be used to set the UID and GID of the process following\n"
340 "the creation of the TCP port listener (which often requires root).\n"
341 "The -b option can be used to specify a FILE containing a list of IP addresses\n"
342 "to block from the server. If a connection from a blocked address is served,\n"
343 "the response file RESPFILE is served instead, if this is provided.")))
346 (let* ((progname (pathname-file (car (argv))))
347 (config (make-config '() '() 70 #t '() '() '() '())))
348 (if (null? (cdr (argv)))
349 (print-usage progname)
350 (let loop ((args (cdr (argv))))
351 (let ((this-arg (car args))
352 (rest-args (cdr args)))
353 (if (string-prefix? "-" this-arg)
355 ((or (equal? this-arg "-h")
356 (equal? this-arg "--help"))
357 (print-usage progname))
358 ((or (equal? this-arg "-n")
359 (equal? this-arg "--no-footer"))
360 (config-display-footer-set! config #f)
362 ((or (equal? this-arg "-u")
363 (equal? this-arg "--user"))
364 (config-user-set! config (string->number (car rest-args)))
365 (loop (cdr rest-args)))
366 ((or (equal? this-arg "-g")
367 (equal? this-arg "--group"))
368 (config-group-set! config (string->number (car rest-args)))
369 (loop (cdr rest-args)))
370 ((or (equal? this-arg "-b")
371 (equal? this-arg "--blacklist"))
372 (config-blacklist-set! config (car rest-args))
373 (loop (cdr rest-args)))
374 ((or (equal? this-arg "-r")
375 (equal? this-arg "--blacklist-resp"))
376 (config-blacklist-resp-set! config (car rest-args))
377 (loop (cdr rest-args)))
379 (print-usage progname)))
381 (config-root-dir-set! config (car args))
382 (config-host-set! config (cadr args))
383 (if (>= (length rest-args) 2)
384 (config-port-set! config (string->number (caddr args))))
385 (run-server config))))))))
390 ;; (run-server (make-config "gopher-root" "localhost" 70 #t '() '() '() '())))