1 ;; The Right-Awful Gemini Server
12 (chicken process-context)
13 (chicken process-context posix)
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")))
24 (define (process-request config request-line)
25 (let ((uri (uri-normalize-path-segments (absolute-uri request-line))))
27 ((not (eq? (uri-scheme uri) 'gemini))
28 (fail-permanent "Unsupported scheme."))
30 (fail-permanent "URL lacks host name."))
31 ((not (equal? (uri-host uri) (config-host config)))
32 (fail-permanent "Proxy requests forbidden."))
33 ((uri-path-relative? uri)
34 (fail-permanent "Path must be absolute."))
35 ((not (document-available? config uri))
36 (fail-permanent "Document not found."))
38 (serve-document config uri)))))
40 (define (fail-permanent reason)
41 (print "50 " reason "\r"))
43 (define (document-available? config uri)
44 (file-exists? (document-path config uri)))
46 (define (document-path config uri)
47 (let* ((crumbs (reverse (cons (config-root-dir config) (cdr (uri-path uri)))))
48 (path (make-pathname (reverse (cdr crumbs)) (car crumbs))))
49 (if (directory-exists? path)
50 (make-pathname path "index.gmi")
53 (define (serve-document config uri)
54 (let* ((path (document-path config uri))
55 (ext (pathname-extension path))
56 (mime-detected (assoc ext file-types))
57 (mime (if mime-detected mime-detected (assoc "txt" file-types)))
58 (mime-type (cadr mime)))
59 (print "20 " (string-intersperse (cdr mime) ";") "\r")
61 ((and (equal? mime-type "text/gemini")
62 (file-executable? path))
63 (serve-text-dynamic path))
64 ((string-prefix? "text/" mime-type)
65 (serve-text-plain path))
66 (else (serve-binary path)))))
68 (define (serve-text-plain path)
69 (with-input-from-file path
71 (let loop ((str (read-string)))
72 (unless (eof-object? str)
74 (loop (read-string)))))))
76 (define (serve-text-dynamic path)
77 (with-input-from-file path
79 (let loop ((c (peek-char)))
86 (serve-dynamic-element (read) (pathname-directory path))
89 (loop (peek-char))))))))
91 (define (serve-dynamic-element element working-directory)
94 (with-current-working-directory
99 (with-current-working-directory
102 (let-values (((in-port out-port id) (process command)))
103 (let ((string (read-string #f in-port)))
104 (unless (eof-object? string)
106 (close-input-port in-port)
107 (close-output-port out-port))))))
108 (else (error "Unknown element type."))))
110 (define (with-current-working-directory directory thunk)
111 (let ((old-wd (current-directory))
115 (change-directory directory)
116 (set! result (thunk))
117 (change-directory old-wd)
120 (change-directory old-wd)
123 (define (run-server config)
124 (set-buffering-mode! (current-output-port) #:line)
125 (define listener (ssl-listen* port: (config-port config)
126 certificate: (config-certfile config)
127 private-key: (config-keyfile config)
130 (print "Host: '" (config-host config) "'\n"
131 "Port: '" (config-port config) "'\n"
132 "Root directory: '" (config-root-dir config) "'\n"
133 "Cert file: '" (config-certfile config) "'\n"
134 "Key file: '" (config-keyfile config) "'\n"
136 "Gemini server listening ...")
139 (server-loop listener config))
141 (define (drop-privs config)
142 (let ((uid (config-uid config))
143 (gid (config-gid config)))
144 (if gid ; Group first, since only root can switch groups.
145 (set! (current-group-id) gid))
147 (set! (current-user-id) uid))))
150 (define (server-loop listener config)
151 (let-values (((in-port out-port) (ssl-accept listener)))
152 (let-values (((local-ip remote-ip) (tcp-addresses (ssl-port->tcp-port in-port))))
153 (print "Accepted connection from " remote-ip
154 " on " (seconds->string))
156 (let ((request-line (read-line in-port)))
157 (print* "Serving request '" request-line "' ... ")
158 (with-output-to-port out-port
160 (process-request config request-line)))
163 (print-error-message o))))
164 (close-input-port in-port)
165 (close-output-port out-port))
166 (server-loop listener config))
169 (define (print-usage progname)
170 (let ((indent-str (make-string (string-length progname) #\space)))
172 progname " [-h/--help]\n"
173 progname " [-p/--port PORT] [-u/--user UID] [-g/--group GID]\n"
174 indent-str " server-root-dir hostname certfile keyfile")))
177 (let* ((progname (pathname-file (car (argv))))
178 (config (make-config #f #f 1965 #f #f #f #f)))
179 (if (null? (cdr (argv)))
180 (print-usage progname)
181 (let loop ((args (cdr (argv))))
182 (let ((this-arg (car args))
183 (rest-args (cdr args)))
184 (if (string-prefix? "-" this-arg)
186 ((or (equal? this-arg "-h")
187 (equal? this-arg "--help"))
188 (print-usage progname))
189 ((or (equal? this-arg "-p")
190 (equal? this-arg "--port"))
191 (config-port-set! config (string->number (car rest-args)))
192 (loop (cdr rest-args)))
193 ((or (equal? this-arg "-u")
194 (equal? this-arg "--user"))
195 (config-uid-set! config (string->number (car rest-args)))
196 (loop (cdr rest-args)))
197 ((or (equal? this-arg "-g")
198 (equal? this-arg "--group"))
199 (config-gid-set! config (string->number (car rest-args)))
200 (loop (cdr rest-args)))
202 (print-usage progname)))
204 ((root-dir host certfile keyfile)
205 (config-root-dir-set! config root-dir)
206 (config-host-set! config host)
207 (config-certfile-set! config certfile)
208 (config-keyfile-set! config keyfile)
211 (print "One or more invalid arguments.")
212 (print-usage progname)))))))))