1 ;; The Right-Awful Gemini Server
12 (chicken process-context)
13 (chicken process-context posix)
14 matchable srfi-13 srfi-1
15 uri-common tcp6 openssl)
18 root-dir host port certfile keyfile uid gid)
21 '(("gmi" "text/gemini" "charset=utf-8")
22 ("txt" "text/plain" "charset=utf-8")
23 ("xml" "text/xml" "charset=utf-8")))
25 (define (process-request config request-line)
26 (let ((uri (uri-normalize-path-segments (absolute-uri request-line))))
28 ((not (eq? (uri-scheme uri) 'gemini))
29 (fail-permanent "Unsupported scheme."))
31 (fail-permanent "URL lacks host name."))
32 ((not (equal? (uri-host uri) (config-host config)))
33 (fail-permanent "Proxy requests forbidden."))
34 ((uri-path-relative? uri)
35 (fail-permanent "Path must be absolute."))
36 ((not (document-available? config uri))
37 (fail-permanent "Document not found."))
38 ((and (document-path-directory? config uri)
39 (uri-lacks-trailing-slash? uri))
40 (redirect-permanent (uri-with-trailing-slash uri)))
42 (serve-document config uri)))))
44 (define (fail-permanent reason)
45 (print "50 " reason "\r"))
47 (define (redirect-permanent new-uri)
48 (print "30 " (uri->string new-uri) "\r"))
50 (define (uri-lacks-trailing-slash? uri)
51 (not (string-null? (last (uri-path uri)))))
53 (define (uri-with-trailing-slash uri)
54 (update-uri uri path: (append (uri-path uri) '(""))))
56 (define (document-available? config uri)
57 (file-exists? (document-path config uri)))
59 (define (document-path-directory? config uri)
60 (directory-exists? (document-path-raw config uri)))
62 (define (document-path-raw config uri)
63 (let* ((crumbs (reverse (cons (config-root-dir config) (cdr (uri-path uri))))))
64 (make-pathname (reverse (cdr crumbs)) (car crumbs))))
66 (define (document-path config uri)
67 (let* ((path (document-path-raw config uri)))
68 (if (directory-exists? path)
69 (make-pathname path "index.gmi")
72 (define (serve-document config uri)
73 (let* ((path (document-path config uri))
74 (ext (pathname-extension path))
75 (mime-detected (assoc ext file-types))
76 (mime (if mime-detected mime-detected (assoc "txt" file-types)))
77 (mime-type (cadr mime)))
78 (print "20 " (string-intersperse (cdr mime) ";") "\r")
80 ((file-executable? path)
81 (serve-text-dynamic path)) ; Binary-files can also be generated here, but the source is dynamic text
82 ((string-prefix? "text/" mime-type)
83 (serve-text-plain path))
84 (else (serve-binary path)))))
86 (define (serve-text-plain path)
87 (with-input-from-file path
89 (let loop ((str (read-string)))
90 (unless (eof-object? str)
92 (loop (read-string)))))))
94 (define (serve-text-dynamic path)
95 (with-input-from-file path
97 (let loop ((c (peek-char)))
104 (serve-dynamic-element (read) (pathname-directory path))
107 (loop (peek-char))))))))
109 (define (serve-dynamic-element element working-directory)
112 (with-current-working-directory
117 (with-current-working-directory
120 (let-values (((in-port out-port id) (process command)))
121 (let ((string (read-string #f in-port)))
122 (unless (eof-object? string)
124 (close-input-port in-port)
125 (close-output-port out-port))))))
126 (else (error "Unknown element type."))))
128 (define (with-current-working-directory directory thunk)
129 (let ((old-wd (current-directory))
133 (change-directory directory)
134 (set! result (thunk))
135 (change-directory old-wd)
138 (change-directory old-wd)
141 (define (run-server config)
142 (set-buffering-mode! (current-output-port) #:line)
143 (define listener (ssl-listen* port: (config-port config)
144 certificate: (config-certfile config)
145 private-key: (config-keyfile config)
148 (print "Host: '" (config-host config) "'\n"
149 "Port: '" (config-port config) "'\n"
150 "Root directory: '" (config-root-dir config) "'\n"
151 "Cert file: '" (config-certfile config) "'\n"
152 "Key file: '" (config-keyfile config) "'\n"
154 "Gemini server listening ...")
157 (server-loop listener config))
159 (define (drop-privs config)
160 (let ((uid (config-uid config))
161 (gid (config-gid config)))
162 (if gid ; Group first, since only root can switch groups.
163 (set! (current-group-id) gid))
165 (set! (current-user-id) uid))))
168 (define (server-loop listener config)
169 (let-values (((in-port out-port) (ssl-accept listener)))
170 (let-values (((local-ip remote-ip) (tcp-addresses (ssl-port->tcp-port in-port))))
171 (print "Accepted connection from " remote-ip
172 " on " (seconds->string))
174 (let ((request-line (read-line in-port)))
175 (print* "Serving request '" request-line "' ... ")
176 (with-output-to-port out-port
178 (process-request config request-line)))
181 (print-error-message o))))
182 (close-input-port in-port)
183 (close-output-port out-port))
184 (server-loop listener config))
187 (define (print-usage progname)
188 (let ((indent-str (make-string (string-length progname) #\space)))
190 progname " [-h/--help]\n"
191 progname " [-p/--port PORT] [-u/--user UID] [-g/--group GID]\n"
192 indent-str " server-root-dir hostname certfile keyfile")))
195 (let* ((progname (pathname-file (car (argv))))
196 (config (make-config #f #f 1965 #f #f #f #f)))
197 (if (null? (cdr (argv)))
198 (print-usage progname)
199 (let loop ((args (cdr (argv))))
200 (let ((this-arg (car args))
201 (rest-args (cdr args)))
202 (if (string-prefix? "-" this-arg)
204 ((or (equal? this-arg "-h")
205 (equal? this-arg "--help"))
206 (print-usage progname))
207 ((or (equal? this-arg "-p")
208 (equal? this-arg "--port"))
209 (config-port-set! config (string->number (car rest-args)))
210 (loop (cdr rest-args)))
211 ((or (equal? this-arg "-u")
212 (equal? this-arg "--user"))
213 (config-uid-set! config (string->number (car rest-args)))
214 (loop (cdr rest-args)))
215 ((or (equal? this-arg "-g")
216 (equal? this-arg "--group"))
217 (config-gid-set! config (string->number (car rest-args)))
218 (loop (cdr rest-args)))
220 (print-usage progname)))
222 ((root-dir host certfile keyfile)
223 (config-root-dir-set! config root-dir)
224 (config-host-set! config host)
225 (config-certfile-set! config certfile)
226 (config-keyfile-set! config keyfile)
229 (print "One or more invalid arguments.")
230 (print-usage progname)))))))))