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1 .\" Copyright (c) 2021 Omar Polo <op@omarpolo.com>
2 .\"
3 .\" Permission to use, copy, modify, and distribute this software for any
4 .\" purpose with or without fee is hereby granted, provided that the above
5 .\" copyright notice and this permission notice appear in all copies.
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7 .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8 .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9 .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
10 .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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12 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
13 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14 .Dd $Mdocdate: January 30 2021$
15 .Dt GMIND 1
16 .Os
17 .Sh NAME
18 .Nm gmid
19 .Nd simple and secure Gemini server
20 .Sh SYNOPSIS
21 .Nm
22 .Bk -words
23 .Op Fl fnv
24 .Op Fl c Ar config
25 .Ek
26 .Nm
27 .Bk -words
28 .Op Fl 6hv
29 .Op Fl d Pa certs-dir
30 .Op Fl H Ar hostname
31 .Op Fl p Ar port
32 .Op Fl x Pa cgi
33 .Op Pa dir
34 .Ek
35 .Sh DESCRIPTION
36 .Nm
37 is a simple and minimal gemini server that can serve static files and
38 execute CGI scripts.
39 It can run without a configuration file with a limited set of features
40 available.
41 .Pp
42 .Nm
43 rereads the configuration file when it receives
44 .Dv SIGHUP .
45 .Pp
46 The options are as follows:
47 .Bl -tag -width 14m
48 .It Fl c Pa config
49 Specify the configuration file.
50 .It Fl f
51 Stays and logs on the foreground.
52 .It Fl n
53 Check that the configuration is valid, but don't start the server.
54 .El
55 .Pp
56 If no configuration file is given,
57 .Nm
58 will look for the following options
59 .Bl -tag -width 14m
60 .It Fl 6
61 Enable IPv6.
62 .It Fl d Pa certs-path
63 Directory where certificates for the config-less mode are stored.
64 By default is
65 .Pa $XDG_DATA_HOME/gmid ,
66 i.e.
67 .Pa ~/.local/share/gmid .
68 .It Fl H Ar hostname
69 The hostname, by default
70 .Ar localhost .
71 Certificates for the given
72 .Ar hostname
73 are searched inside the
74 .Pa certs-dir
75 directory given with the
76 .Fl d
77 option.
78 They have the form
79 .Pa hostname.cert.pem
80 and
81 .Pa hostname.key.pem .
82 If a certificate and key doesn't exists for a given hostname they
83 will be automatically generated.
84 .It Fl h
85 Print the usage and exit.
86 .It Fl p Ar port
87 The port to listen on, by default 1965.
88 .It Fl v
89 Increase the verbosity of the logs.
90 .It Fl x Pa path
91 Enable execution of CGI scripts.
92 See the description of the
93 .Ic cgi
94 option in the section
95 .Sq Servers
96 below to learn how
97 .Pa path
98 is processed.
99 Cannot be provided more than once.
100 .It Pa dir
101 The root directory to serve.
102 By default the current working directory is assumed.
103 .El
104 .Sh CONFIGURATION FILE
105 The configuration file is divided into two sections:
106 .Bl -tag -width xxxx
107 .It Sy Global Options
108 Global settings for
109 .Nm .
110 .It Sy Servers
111 Virtual hosts definition.
112 .El
113 .Pp
114 Within the sections, empty lines are ignored and comments can be put
115 anywhere in the file using a hash mark
116 .Pq Sq # ,
117 and extend to the end of the current line.
118 A boolean is either the symbol
119 .Sq on
120 or
121 .Sq off .
122 A string is a sequence of characters wrapped in double quotes,
123 .Dq like this .
124 .Ss Global Options
125 .Bl -tag -width 12m
126 .It Ic chroot Pa path
127 .Xr chroot 2
128 the process to the given
129 .Pa path .
130 The daemon has to be run with root privileges and thus the option
131 .Ic user
132 needs to be provided, so privileges can be dropped.
133 Note that
134 .Nm
135 will enter the chroot after loading the TLS keys, but before opening
136 the virtual host root directories.
137 It's recommended to keep the TLS keys outside the chroot.
138 Future version of
139 .Nm
140 may require this.
141 .It Ic ipv6 Ar bool
142 Enable or disable IPv6 support.
143 By default is off.
144 .It Ic mime Ar mime-type Ar file-extension
145 Add a mapping for the given
146 .Ar file-extension
147 to the given
148 .Ar mime-type .
149 Both argument are strings.
150 .It Ic port Ar portno
151 The port to listen on.
152 By default is 1965.
153 .It Ic protocols Ar string
154 Specify the TLS protocols to enable.
155 Refer to
156 .Xr tls_config_parse_protocols 3
157 for the valid protocol string values.
158 By default, both TLSv1.3 and TLSv1.2 are enabled.
159 Use
160 .Dq tlsv1.3
161 to enable only TLSv1.3.
162 .It Ic user Ar string
163 Run the daemon as the given user.
164 .El
165 .Ss Servers
166 Every virtual host is defined by a
167 .Ic server
168 block:
169 .Bl -tag -width Ds
170 .It Ic server Ar hostname Brq ...
171 Match the server name using shell globbing rules.
172 This can be an explicit name,
173 .Ar www.example.com ,
174 or a name including a wildcards,
175 .Ar *.example.com .
176 .El
177 .Pp
178 Followed by a block of options that is enclosed in curly brackets:
179 .Bl -tag -width Ds
180 .It Ic auto Ic index Ar bool
181 If no index file is found, automatically generate a directory listing.
182 It's disabled by default.
183 .It Ic block Op Ic return Ar code Op Ar meta
184 Send a reply and close the connection;
185 .Ar code
186 is 40
187 and
188 .Ar meta
189 is
190 .Dq temporary failure
191 by default.
192 If
193 .Ar code
194 is in the 3x range, then
195 .Ar meta
196 must be provided.
197 Inside
198 .Ar meta ,
199 the following special sequences are replaced:
200 .Bl -tag -compact
201 .It \&%\&%
202 is replaced with a single
203 .Sq \&% .
204 .It \&%p
205 is replaced with the request path.
206 .It \&%q
207 is replaced with the query string of the request.
208 .It \&%P
209 is replaced with the server port.
210 .It \&%N
211 is replaced with the server name.
212 .El
213 .It Ic cert Pa file
214 Path to the certificate to use for this server.
215 The
216 .Pa file
217 should contain a PEM encoded certificate.
218 This option is mandatory.
219 .It Ic cgi Pa path
220 Execute CGI scripts that matches
221 .Pa path
222 using shell globbing rules.
223 .It Ic default type Ar string
224 Set the default media type that is used if the media type for a
225 specified extension is not found.
226 If not specified, the
227 .Ic default type
228 is set to
229 .Dq application/octet-stream .
230 .It Ic entrypoint Pa path
231 Make the CGI script at
232 .Pa path
233 .Pq relative to the Ic root No directory
234 handle all the requests for the current virtual host
235 .It Ic index Ar string
236 Set the directory index file.
237 If not specified, it defaults to
238 .Pa index.gmi .
239 .It Ic key Pa file
240 Specify the private key to use for this server.
241 The
242 .Pa file
243 should contain a PEM encoded private key.
244 This option is mandatory.
245 .It Ic lang Ar string
246 Specify the language tag for the text/gemini content served.
247 If not specified, no
248 .Dq lang
249 parameter will be added in the response.
250 .It Ic location Pa path Brq ...
251 Specify server configuration rules for a specific location.
252 The
253 .Pa path
254 argument will be matched against the request path with shell globbing
255 rules.
256 In case of multiple location statements in the same context, the first
257 matching location will be put into effect and the later ones ignored.
258 Therefore is advisable to match for more specific paths first and for
259 generic ones later on.
261 .Ic location
262 section may include most of the server configuration rules
263 except
264 .Ic cert , Ic key , Ic root , Ic location ,
265 .Ic entrypoint No and Ic cgi .
266 .It Ic root Pa directory
267 Specify the root directory for this server.
268 This option is mandatory.
269 It's relative to the chroot, if enabled.
270 .It Ic strip Ar number
271 Strip
272 .Ar number
273 components from the beginning of the path.
274 It's only considered for the
275 .Ar meta
276 parameter in the scope of a
277 .Ic block return .
278 .El
279 .Sh CGI
280 When a request for an executable file matches the
281 .Ic cgi
282 rule, that file will be execute and its output fed to the client.
283 .Pp
284 The CGI scripts are executed in the directory they reside and inherit
285 the environment from
286 .Nm
287 with these additional variables set:
288 .Bl -tag -width 24m
289 .It Ev GATEWAY_INTERFACE
290 .Dq CGI/1.1
291 .It Ev GEMINI_DOCUMENT_ROOT
292 The root directory of the virtual host.
293 .It Ev GEMINI_SCRIPT_FILENAME
294 Full path to the CGI script being executed.
295 .It Ev GEMINI_URL
296 The full IRI of the request.
297 .It Ev GEMINI_URL_PATH
298 The path of the request.
299 .It Ev PATH_INFO
300 The portion of the requested path that is derived from the the IRI
301 path hierarchy following the part that identifies the script itself.
302 Can be unset.
303 .It Ev PATH_TRANSLATED
304 Present if and only if
305 .Ev PATH_INFO
306 is set.
307 It represent the translation of the
308 .Ev PATH_INFO .
309 .Nm
310 builds this by appending the
311 .Ev PATH_INFO
312 to the virtual host directory root.
313 .It Ev QUERY_STRING
314 The decoded query string.
315 .It Ev REMOTE_ADDR , Ev REMOTE_HOST
316 Textual representation of the client IP.
317 .It Ev REQUEST_METHOD
318 This is present only for RFC3875 (CGI) compliance.
319 It's always set to the empty string.
320 .It Ev SCRIPT_NAME
321 The part of the
322 .Ev GEMINI_URL_PATH
323 that identifies the current CGI script.
324 .It Ev SERVER_NAME
325 The name of the server
326 .It Ev SERVER_PORT
327 The port the server is listening on.
328 .It Ev SERVER_PROTOCOL
329 .Dq GEMINI
330 .It Ev SERVER_SOFTWARE
331 The name and version of the server, i.e.
332 .Dq gmid/1.5
333 .It Ev AUTH_TYPE
334 The string "Certificate" if the client used a certificate, otherwise
335 unset.
336 .It Ev REMOTE_USER
337 The subject of the client certificate if provided, otherwise unset.
338 .It Ev TLS_CLIENT_ISSUER
339 The is the issuer of the client certificate if provided, otherwise
340 unset.
341 .It Ev TLS_CLIENT_HASH
342 The hash of the client certificate if provided, otherwise unset.
343 The format is
344 .Dq ALGO:HASH .
345 .El
346 .Pp
347 .Sh MIME
348 To auto-detect the MIME type of the response
349 .Nm
350 looks at the file extension and consults its internal table.
351 By default the following mappings are loaded, but they can be
352 overridden or extended using the
353 .Ic mime
354 configuration option.
355 If no MIME is found, the value of
356 .Ic default type
357 matching the file
358 .Ic location
359 will be used, which is
360 .Dq application/octet-stream
361 by default.
362 .Pp
363 .Bl -tag -offset indent -width 14m -compact
364 .It gemini, gmi
365 text/gemini
366 .It gif
367 image/gif
368 .It jpeg
369 image/jpeg
370 .It jpg
371 image/jpeg
372 .It markdown, md
373 text/markdown
374 .It pdf
375 application/pdf
376 .It png
377 image/png
378 .It svg
379 image/svg+xml
380 .It txt
381 text/plain
382 .It xml
383 text/xml
384 .El
385 .Sh EXAMPLES
386 Serve the current directory
387 .Bd -literal -offset indent
388 $ gmid .
389 .Ed
390 .Pp
391 To serve the directory
392 .Pa docs
393 and enable CGI scripts inside
394 .Pa docs/cgi ,
395 you can
396 .Bd -literal -offset indent
397 $ mkdir docs/cgi
398 $ cat <<EOF > cgi/hello
399 #!/bin/sh
400 printf "20 text/plain\\r\\n"
401 echo "hello world"
402 EOF
403 $ chmod +x docs/cgi/hello
404 $ gmid -x cgi docs
405 .Ed
406 .Pp
407 The following is an example of a possible configuration for a site
408 that enables only TLSv1.3, adds a mime type for the file extension
409 "rtf" and defines two virtual host:
410 .Bd -literal -offset indent
411 ipv6 on # enable ipv6
413 protocols "tlsv1.3"
415 mime "application/rtf" "rtf"
417 server "example.com" {
418 cert "/path/to/cert.pem"
419 key "/path/to/key.pem"
420 root "/var/gemini/example.com"
423 server "it.example.com" {
424 cert "/path/to/cert.pem"
425 key "/path/to/key.pem"
426 root "/var/gemini/it.example.com"
427 cgi "/cgi-bin/*"
428 lang "it"
430 .Ed
431 .Pp
432 Yet another example, showing how to enable a
433 .Ic chroot
434 and use
435 .Ic location
436 rule
437 .Bd -literal -offset indent
438 chroot "/var/gemini"
439 user "_gmid"
441 server "example.com" {
442 cert "/path/to/cert.pem"
443 key "/path/to/key.pem"
444 root "/example.com" # in the /var/gemini chroot
446 location "/static/*" {
447 auto index on
448 index "index.gemini"
451 .Ed
452 .Sh ACKNOWLEDGEMENTS
453 .Nm
454 uses the
455 .Dq Flexible and Economical
456 UTF-8 decoder written by
457 .An Bjoern Hoehrmann .
458 .Sh AUTHORS
459 .An -nosplit
460 The
461 .Nm
462 program was written by
463 .An Omar Polo Aq Mt op@omarpolo.com .
464 .Sh CAVEATS
465 .Bl -bullet
466 .It
467 The root directories of all virtual hosts are opened during the daemon
468 startup; this means that if a root directory gets deleted and then
469 re-created,
470 .Nm
471 won't be able to serve files inside that directory until a restart.
472 This restriction applies only to the root directories and not their content.
473 .It
474 a %2F sequence is indistinguishable from a literal slash: this is not
475 RFC3986-compliant.
476 .It
477 a %00 sequence is treated as invalid character and thus rejected.
478 .El