1 ;; The Right-Awful Gemini Server
3 ;; This is a gemini server in the spirit of the
4 ;; scratchy gopher server. Just as for that server,
5 ;; rags uses runtime evaluation of embedded scheme
6 ;; expressions to provide dynamically generated content.
8 ;; See the readme for details.
18 (chicken process-context)
19 (chicken process-context posix)
20 matchable srfi-13 srfi-1
21 uri-common tcp6 openssl)
24 root-dir host port certfile keyfile uid gid)
27 '(("gmi" "text/gemini" "charset=utf-8")
28 ("txt" "text/plain" "charset=utf-8")
29 ("csv" "text/csv" "charset=utf-8")
30 ("html" "text/html" "charset=utf-8")
31 ("xml" "text/xml" "charset=utf-8")
32 ("pdf" "application/pdf")
33 ("zip" "application/zip")
37 ("mp3" "audio/mpeg")))
39 (define eval-env-file "eval-env.scm")
40 (define eval-env (interaction-environment))
42 (define (process-request config request-line)
43 (let ((uri (uri-normalize-path-segments (absolute-uri request-line))))
45 ((not (eq? (uri-scheme uri) 'gemini))
46 (fail-permanent "Unsupported scheme."))
48 (fail-permanent "URL lacks host name."))
49 ((not (equal? (uri-host uri) (config-host config)))
50 (fail-permanent "Proxy requests forbidden."))
51 ((uri-path-relative? uri)
52 (fail-permanent "Path must be absolute."))
53 ((not (document-available? config uri))
54 (fail-permanent "Document not found."))
55 ((and (document-path-directory? config uri)
56 (uri-lacks-trailing-slash? uri))
57 (redirect-permanent (uri-with-trailing-slash uri)))
58 ((document-script? config uri)
59 (serve-script config uri))
61 (serve-document config uri)))))
63 (define (fail-permanent reason)
64 (print "50 " reason "\r"))
66 (define (redirect-permanent new-uri)
67 (print "30 " (uri->string new-uri) "\r"))
69 (define (serve-query prompt)
70 (print "10 " prompt "\r"))
72 (define (uri-lacks-trailing-slash? uri)
73 (not (string-null? (last (uri-path uri)))))
75 (define (uri-with-trailing-slash uri)
76 (update-uri uri path: (append (uri-path uri) '(""))))
78 (define (document-available? config uri)
79 (file-exists? (document-path config uri)))
81 (define (document-script? config uri)
82 (let ((path (document-path config uri)))
83 (and (file-exists? path)
84 (file-executable? path)
85 (equal? (pathname-extension path) "scm"))))
87 (define (document-path-directory? config uri)
88 (directory-exists? (document-path-raw config uri)))
90 (define (document-path-raw config uri)
91 (let* ((crumbs (reverse (cons (config-root-dir config) (cdr (uri-path uri))))))
92 (make-pathname (reverse (cdr crumbs)) (car crumbs))))
94 (define (document-path config uri)
95 (let* ((path (document-path-raw config uri)))
96 (if (directory-exists? path)
97 (make-pathname path "index.gmi")
100 (define (ext->mime ext)
101 (let* ((mime-detected (assoc ext file-types)))
102 (cdr (if mime-detected
104 (assoc "txt" file-types)))))
106 (define (serve-document-header mime)
107 (print "20 " (string-intersperse mime ";") "\r"))
109 (define (serve-document config uri)
110 (let* ((path (document-path config uri))
111 (ext (pathname-extension path))
112 (mime (ext->mime ext)))
113 (serve-document-header mime)
115 ((file-executable? path)
116 (serve-text-dynamic path)) ; Binary-files can also be generated here, but the source is dynamic text
117 ((string-prefix? "text/" (car mime))
118 (serve-text-plain path))
119 (else (serve-binary path)))))
121 (define (serve-text-plain path)
122 (with-input-from-file path
124 (let loop ((str (read-string)))
125 (unless (eof-object? str)
127 (loop (read-string)))))))
129 (define (serve-text-dynamic path)
130 (with-input-from-file path
132 (let loop ((c (peek-char)))
139 (serve-dynamic-element (read) (pathname-directory path))
142 (loop (peek-char))))))))
144 (define (serve-dynamic-element element working-directory)
147 (with-current-working-directory
150 (eval expression eval-env))))
152 (with-current-working-directory
155 (let-values (((in-port out-port id) (process command)))
156 (let ((string (read-string #f in-port)))
157 (unless (eof-object? string)
159 (close-input-port in-port)
160 (close-output-port out-port))))))
161 (else (error "Unknown element type."))))
163 (define (serve-script config uri)
164 ;; Scripts are responsible for the entire response, including header
165 (let* ((path (document-path config uri))
166 (proc (eval (with-input-from-file path read) eval-env)))
167 (with-current-working-directory
168 (pathname-directory (document-path config uri))
170 (apply proc (list uri))))))
172 (define (with-current-working-directory directory thunk)
173 (let ((old-wd (current-directory))
177 (change-directory directory)
178 (set! result (thunk))
179 (change-directory old-wd)
182 (change-directory old-wd)
185 (define (run-server config)
186 (set-buffering-mode! (current-output-port) #:line)
187 (define listener (ssl-listen* port: (config-port config)
188 certificate: (config-certfile config)
189 private-key: (config-keyfile config)
192 (print "Host: '" (config-host config) "'\n"
193 "Port: '" (config-port config) "'\n"
194 "Root directory: '" (config-root-dir config) "'\n"
195 "Cert file: '" (config-certfile config) "'\n"
196 "Key file: '" (config-keyfile config) "'\n")
198 (print* "Dropping privilages ... ")
202 (print* "Setting up environment ... ")
206 (print "\nGemini server listening ...")
207 (server-loop listener config))
209 (define (setup-env config)
210 (with-current-working-directory
211 (config-root-dir config)
213 (if (and (file-exists? eval-env-file) (file-readable? eval-env-file))
214 (with-input-from-file eval-env-file
216 (let loop ((next-expr (read)))
217 (unless (eof-object? next-expr)
218 (eval next-expr eval-env)
219 (loop (read))))))))))
221 (define (drop-privs config)
222 (let ((uid (config-uid config))
223 (gid (config-gid config)))
224 (if gid ; Group first, since only root can switch groups.
225 (set! (current-group-id) gid))
227 (set! (current-user-id) uid))))
230 (define (server-loop listener config)
231 (let-values (((in-port out-port) (ssl-accept listener)))
232 (let-values (((local-ip remote-ip) (tcp-addresses (ssl-port->tcp-port in-port))))
233 (print "Accepted connection from " remote-ip
234 " on " (seconds->string))
236 (let ((request-line (read-line in-port)))
237 (print* "Serving request '" request-line "' ... ")
238 (with-output-to-port out-port
240 (process-request config request-line)))
243 (print-error-message o))))
244 (close-input-port in-port)
245 (close-output-port out-port))
246 (server-loop listener config))
249 (define (print-usage progname)
250 (let ((indent-str (make-string (string-length progname) #\space)))
252 progname " [-h/--help]\n"
253 progname " [-p/--port PORT] [-u/--user UID] [-g/--group GID]\n"
254 indent-str " server-root-dir hostname certfile keyfile")))
257 (let* ((progname (pathname-file (car (argv))))
258 (config (make-config #f #f 1965 #f #f #f #f)))
259 (if (null? (command-line-arguments))
260 (print-usage progname)
261 (let loop ((args (command-line-arguments)))
262 (let ((this-arg (car args))
263 (rest-args (cdr args)))
264 (if (string-prefix? "-" this-arg)
266 ((or (equal? this-arg "-h")
267 (equal? this-arg "--help"))
268 (print-usage progname))
269 ((or (equal? this-arg "-p")
270 (equal? this-arg "--port"))
271 (config-port-set! config (string->number (car rest-args)))
272 (loop (cdr rest-args)))
273 ((or (equal? this-arg "-u")
274 (equal? this-arg "--user"))
275 (config-uid-set! config (string->number (car rest-args)))
276 (loop (cdr rest-args)))
277 ((or (equal? this-arg "-g")
278 (equal? this-arg "--group"))
279 (config-gid-set! config (string->number (car rest-args)))
280 (loop (cdr rest-args)))
282 (print-usage progname)))
284 ((root-dir host certfile keyfile)
285 (config-root-dir-set! config root-dir)
286 (config-host-set! config host)
287 (config-certfile-set! config certfile)
288 (config-keyfile-set! config keyfile)
291 (print "One or more invalid arguments.")
292 (print-usage progname)))))))))