13 (chicken process-context)
14 srfi-1 srfi-13 matchable)
17 ;; (use srfi-1 srfi-13 tcp posix matchable)
21 (define gopher-index-filename "index")
23 (define burrower-version "1.0.0")
25 (define burrower-footer
27 "--------------------------------------------------\n"
28 "This gopher hole was dug using Burrower v" burrower-version ".\n"
29 "Powered by Chicken Scheme!"))
33 ;; We don't yet use worker threads here to handle requests,
34 ;; the server just blocks until the first request is finished.
35 ;; While we should fix this, it's actually probably okay, as
36 ;; we genuinely don't expect a huge flood of gopher traffic. :-(
38 (define-record config root-dir host port display-footer)
40 (define (run-server config)
41 (set-buffering-mode! (current-output-port) #:line)
42 (print "Gopher server listening on port " (config-port config) " ...")
43 (let ((listener (tcp-listen (config-port config))))
45 (let-values (((in-port out-port) (tcp-accept listener)))
46 (let* ((line (read-line in-port))
47 (selector (string-trim-both line)))
48 (let-values (((local-ip remote-ip) (tcp-addresses in-port)))
49 (print "Accepted connection from " remote-ip
50 " on " (seconds->string))
53 (with-output-to-port out-port
55 (serve-selector (if (= (string-length selector) 0)
59 (print "... served selector '" selector "'. Closing connection."))
61 (print-error-message o out-port)
62 (print-error-message o)
63 (print "Error while attempting to serve selector " selector ".")))))
64 (close-input-port in-port)
65 (close-output-port out-port))
67 (tcp-close listener)))
70 ;;; Selector type inference
72 (define (true-for-one? predicate values)
75 (if (predicate (car values))
77 (true-for-one? predicate (cdr values)))))
79 (define (has-suffix? selector . suffixes)
80 (true-for-one? (lambda (suffix)
81 (string-suffix? suffix selector))
84 (define (has-prefix? selector . prefixes)
85 (true-for-one? (lambda (prefix)
86 (string-prefix? prefix selector))
89 (define (infer-selector-type selector)
90 (let ((l (string-downcase selector)))
92 ((or (= (string-length l) 0)
93 (string-suffix? "/" l)
94 (string-contains l ":")) 1)
95 ((has-suffix? l ".txt" ".org" ".md") 0)
96 ((has-suffix? l ".png" ".jpg" ".gif" ".bmp" ".tif" ".tga") 'I)
97 ((has-suffix? l "?" "%3f") 7)
98 ((has-prefix? l "url:" "/url:") 'h)
102 ;;; Selector retrieval
104 (define (serve-selector raw-selector config)
105 (let* ((selector-list (string-split raw-selector "\t"))
106 (selector (car selector-list))
107 (arguments (cdr selector-list)))
108 (case (infer-selector-type selector)
109 ((1) (if (string-contains selector ":")
110 (let ((l (string-split selector ":")))
111 (serve-directory-script (car l) (cdr l)
113 (serve-directory-file selector config)))
114 ((7) (let ((l (string-split selector "?")))
115 (serve-directory-script (car l) arguments config)))
116 ((0) (serve-text-file selector config))
117 ((h) (serve-url selector config))
118 (else (serve-binary-file selector config)))))
120 (define (legal-filename? filename config)
121 (and (string-prefix? (config-root-dir config)
122 (normalize-pathname filename))
123 (file-exists? filename)
124 (not (directory-exists? filename))
125 (file-readable? filename)))
127 (define (legal-script-filename? filename config)
128 (and (legal-filename? filename config)
129 (string-suffix? ".scm" filename)
130 (file-executable? filename)))
132 (define (serve-directory-script selector arguments config)
133 (let ((filename (make-pathname (config-root-dir config) selector)))
134 (if (legal-script-filename? filename config)
135 (let* ((sexp (with-input-from-file filename read))
136 (selector-dir (pathname-directory selector)))
137 (serve-records (with-selector-dir
140 (apply (eval sexp) arguments)))
143 (error "No legal index script not found." filename))))
145 (define (serve-directory-file selector config)
146 (let ((filename (make-pathname (list (config-root-dir config) selector)
147 gopher-index-filename)))
148 (if (legal-filename? filename config)
150 (with-input-from-file filename
152 (let loop ((c (peek-char)))
159 (serve-record (read) selector config)
161 (serve-info-records (read-line)))
162 (loop (peek-char)))))))
163 (if (config-display-footer config)
164 (serve-info-records burrower-footer))
166 (error "No legal index file not found."))))
168 (define (serve-text-file selector config)
169 (let ((filename (make-pathname (config-root-dir config) selector)))
170 (if (legal-filename? filename config)
172 (with-input-from-file filename
179 (error "File not found." filename))))
181 (define (serve-binary-file selector config)
182 (let ((filename (make-pathname (config-root-dir config) selector)))
183 (if (legal-filename? filename config)
184 (with-input-from-file filename
186 (let loop ((b (read-byte)))
191 (loop (read-byte)))))))
192 (error "File not found." filename))))
194 (define (serve-url selector config)
195 (let ((url (substring selector 4)))
197 "<html><head><title>Redirection</title>"
198 "<meta http-equiv=\"refresh\" content=\"10; URL='" url "'\" />"
200 "<p>If you are seeing this page, your gopher browser does not "
201 "properly support URL directory entries or cannot follow such "
203 "<p>If you are viewing this page using a web browser, you should "
204 "be redirected shortly. Otherwise, you can manually open the "
205 "the follwing url:\n"
207 "<a href=\"" url "\">" url "</a>\n"
213 (define (serve-records records dir-selector config)
216 (serve-record record dir-selector config))
219 (define (serve-info-records string)
223 (for-each (lambda (char)
224 (print* (if (eq? char #\tab)
228 (print "\tfake\tfake\t1\r"))
229 (string-split string "\n" #t)))
231 (define (serve-record record dir-selector config)
233 ((? string?) (serve-info-records record))
234 (('shell command) (serve-shell-command command dir-selector config))
235 (('eval expression) (serve-expression expression dir-selector config))
236 (('url display-string url)
237 (print #\h display-string "\tURL:" url
238 "\t" (config-host config)
239 "\t" (config-port config) "\r"))
240 ((type display-string selector host port)
241 (print type display-string "\t" selector "\t" host "\t" port "\r"))
242 ((type display-string selector host)
243 (serve-record (list type display-string selector host 70)
244 dir-selector config))
245 ((type display-string selector)
246 (serve-record (list type display-string
247 (make-pathname dir-selector selector)
248 (config-host config) (config-port config))
249 dir-selector config))
250 ((display-string selector)
251 (serve-record (list (infer-selector-type selector) display-string selector)
252 dir-selector config))
254 (serve-record (list (infer-selector-type selector) selector)
255 dir-selector config))
256 (else (error "Unknown record type."))))
258 (define (serve-shell-command command dir-selector config)
262 (let-values (((in-port out-port id) (process command)))
263 (let ((string (read-string #f in-port)))
264 (if (and (not (eof-object? string))
265 (> (string-length string) 0))
266 (serve-info-records (string-chomp string "\n"))))))))
268 (define (serve-expression expression dir-selector config)
272 (serve-records (eval expression) dir-selector config))))
277 (define (with-current-working-directory directory thunk)
278 (let ((old-wd (current-directory))
282 (change-directory directory)
283 (set! result (thunk))
284 (change-directory old-wd)
287 (change-directory old-wd)
290 (define (with-selector-dir selector config thunk)
291 (with-current-working-directory
292 (make-pathname (config-root-dir config)
293 (pathname-directory selector)) thunk))
298 (define (print-usage progname)
300 progname " -h/--help\n"
301 progname " [-n/--no-footer] gopher-root-dir server-hostname [server-port]\n"
303 "The -n option tells the server to not display a directory footer."))
306 (let* ((progname (car (argv)))
308 (config (make-config '() '() 70 #t)))
311 (equal? (car args) "-h")
312 (equal? (car args) "--help"))
313 (print-usage progname)
315 (if (or (equal? (car args) "-n")
316 (equal? (car args) "--no-footer"))
318 (config-display-footer-set! config #f)
319 (set! args (cdr args))))
320 (if (or (< (length args) 2)
322 (print-usage progname)
324 (config-root-dir-set! config (car args))
325 (config-host-set! config (cadr args))
326 (if (= (length args) 3)
327 (config-port-set! config (string->number (caddr args))))
328 (run-server config)))))))
333 (run-server (make-config "gopher-root" "localhost" 70 #t)))