3 b9231167 2021-02-08 op gmid is a fast Gemini server written with security in mind. I
4 b9231167 2021-02-08 op initially wrote it to serve static files, but it has grown into a
5 747b35d0 2021-02-08 op featureful server.
10 601bc1cc 2021-01-30 op (random order)
12 747b35d0 2021-02-08 op - reconfiguration: reload the running configuration without
14 86edc4f4 2021-02-04 op - sandboxed by default on OpenBSD, Linux and FreeBSD
15 4d2ec6d7 2021-01-13 op - IRI support (RFC3987)
16 286c4f40 2021-01-27 op - punycode support
17 601bc1cc 2021-01-30 op - dual stack (IPv4 and IPv6)
18 601bc1cc 2021-01-30 op - automatic certificate generation for config-less mode
20 b9220ca4 2021-01-11 op - (very) low memory footprint
21 b9231167 2021-02-08 op - event-based asynchronous I/O model
22 b9220ca4 2021-01-11 op - small codebase, easily hackable
23 b9220ca4 2021-01-11 op - virtual hosts
24 286c4f40 2021-01-27 op - per-location rules
25 286c4f40 2021-01-27 op - optional directory listings
26 286c4f40 2021-01-27 op - configurable mime types
27 0b00962d 2021-01-25 op - chroot support
30 286c4f40 2021-01-27 op ## Internationalisation (IRIs, UNICODE, punycode, all that stuff)
32 286c4f40 2021-01-27 op Even thought the current Gemini specification doesn't mention anything
33 601bc1cc 2021-01-30 op in this regard, I do think these are important things and so I tried
34 601bc1cc 2021-01-30 op to implement them in the most user-friendly way I could think of.
36 601bc1cc 2021-01-30 op For starters, gmid has full support for IRI (RFC3987 —
37 22a742e4 2021-01-29 op Internationalized Resource Identifiers). IRIs are a superset of URIs,
38 286c4f40 2021-01-27 op so there aren't incompatibilities with URI-only clients.
40 601bc1cc 2021-01-30 op There is full support also for punycode. In theory, the user doesn't
41 286c4f40 2021-01-27 op even need to know that punycode is a thing. The hostname in the
42 601bc1cc 2021-01-30 op configuration file can (and must be) in the decoded form (e.g. `naïve`
43 601bc1cc 2021-01-30 op and not `xn--nave-6pa`), gmid will do the rest.
45 601bc1cc 2021-01-30 op The only missing piece is UNICODE normalisation of the IRI path: gmid
46 601bc1cc 2021-01-30 op doesn't do that (yet).
49 1487e11e 2021-02-06 op ## Configuration
51 1487e11e 2021-02-06 op gmid has a rich configuration file, heavily inspired by OpenBSD'
52 1487e11e 2021-02-06 op httpd. While you should definitely check the manpage because it
53 1487e11e 2021-02-06 op documents every option in depth, here's an example of what gmid can
57 1487e11e 2021-02-06 op ipv6 on # enable ipv6
59 1487e11e 2021-02-06 op server "example.com" {
60 1487e11e 2021-02-06 op cert "/path/to/cert.pem"
61 1487e11e 2021-02-06 op key "/path/to/key.pem"
62 1487e11e 2021-02-06 op root "/var/gemini/example.com"
66 1487e11e 2021-02-06 op location "/files/*" {
70 1487e11e 2021-02-06 op location "/repo/*" {
71 1487e11e 2021-02-06 op # change the index file name
72 1487e11e 2021-02-06 op index "README.gmi"
75 1487e11e 2021-02-06 op # redirect /cgi/man/... to man.example.com/...
76 1487e11e 2021-02-06 op location "/cgi/man*" {
78 1487e11e 2021-02-06 op block return 31 "gemini://man.example.com%p"
82 1487e11e 2021-02-06 op server "man.example.com" {
85 1487e11e 2021-02-06 op root "/var/gemini/man.example.com"
87 1487e11e 2021-02-06 op # handle every request with the CGI script `man'
88 1487e11e 2021-02-06 op entrypoint "man"
95 b9231167 2021-02-08 op gmid depends on a POSIX libc, libevent2, OpenSSL/LibreSSL and libtls
96 b9231167 2021-02-08 op (provided either by LibreSSL or libretls). At build time, flex and
97 b9231167 2021-02-08 op yacc (or GNU bison) are also needed.
99 771d8f28 2021-01-17 op The build is as simple as
104 8f0da580 2021-01-21 op If the configure scripts fails to pick up something, please open an
105 f980545b 2021-01-21 op issue or notify me via email.
107 771d8f28 2021-01-17 op To install execute:
113 601bc1cc 2021-01-30 op If you have trouble installing LibreSSL or libretls, you can use
114 601bc1cc 2021-01-30 op Docker to build a `gmid` image with:
116 17b09e3c 2021-01-18 op docker build -t gmid .
118 17b09e3c 2021-01-18 op and then run it with something along the lines of
120 17b09e3c 2021-01-18 op docker run --rm -it -p 1965:1965 \
121 6c117838 2021-01-25 op -v /path/to/gmid.conf:...:ro \
122 17b09e3c 2021-01-18 op -v /path/to/docs:/var/gemini \
123 6c117838 2021-01-25 op gmid -c .../gmid.conf
125 601bc1cc 2021-01-30 op (ellipses used for brevity)
127 dd8cc7d3 2021-01-22 op ### Local libretls
129 8f0da580 2021-01-21 op This is **NOT** recommended, please try to port LibreSSL/LibreTLS to
130 8f0da580 2021-01-21 op your distribution of choice or use docker instead.
132 601bc1cc 2021-01-30 op However, it's possible to statically-link `gmid` to locally-installed
133 601bc1cc 2021-01-30 op libretls quite easily. (It's how I test gmid on Fedora, for instance)
135 04397b32 2021-01-21 op Let's say you have compiled and installed libretls in `$LIBRETLS`,
136 8f0da580 2021-01-21 op then you can build `gmid` with
138 04397b32 2021-01-21 op ./configure CFLAGS="-I$LIBRETLS/include" \
139 1606927e 2021-02-11 op LDFLAGS="$LIBRETLS/lib/libtls.a -lssl -lcrypto -lpthread -levent"
148 601bc1cc 2021-01-30 op to start the suite. Keep in mind that the regression tests will
149 601bc1cc 2021-01-30 op create files inside the `regress` directory and bind the 10965 port.
152 881a9dd9 2021-01-16 op ## Architecture/Security considerations
154 881a9dd9 2021-01-16 op gmid is composed by two processes: a listener and an executor. The
155 881a9dd9 2021-01-16 op listener process is the only one that needs internet access and is
156 881a9dd9 2021-01-16 op sandboxed. When a CGI script needs to be executed, the executor
157 881a9dd9 2021-01-16 op (outside of the sandbox) sets up a pipe and gives one end to the
158 881a9dd9 2021-01-16 op listener, while the other is bound to the CGI script standard output.
159 909ea500 2021-01-27 op This way, is still possible to execute CGI scripts without
160 601bc1cc 2021-01-30 op restrictions even in the presence of a sandboxed network process.
162 601bc1cc 2021-01-30 op On OpenBSD, the listener runs with the `stdio recvfd rpath inet`
163 601bc1cc 2021-01-30 op pledges, while the executor has `stdio sendfd proc exec`; both have
164 601bc1cc 2021-01-30 op unveiled only the served directories.
166 ea58dab1 2021-01-17 op On FreeBSD, the executor process is sandboxed with `capsicum(4)`.
168 601bc1cc 2021-01-30 op On Linux, a `seccomp(2)` filter is installed in the listener to allow
169 601bc1cc 2021-01-30 op only certain syscalls, see [sandbox.c](sandbox.c) for more information
170 601bc1cc 2021-01-30 op on the BPF program.
172 ea58dab1 2021-01-17 op In any case, you are invited to run gmid inside some sort of
173 0b00962d 2021-01-25 op container/jail/chroot.