3 b9220ca4 2021-01-11 op > dead simple, zero configuration Gemini server
5 881a9dd9 2021-01-16 op gmid is a simple and minimal Gemini server. It can run without
6 881a9dd9 2021-01-16 op configuration, so it's well suited for local development, but at the
7 881a9dd9 2021-01-16 op same time has a configuration file flexible enough to meet the
8 881a9dd9 2021-01-16 op requirements of most capsules.
10 881a9dd9 2021-01-16 op gmid was initially written to serve static files, but can also
11 881a9dd9 2021-01-16 op optionally execute CGI scripts. It was also written with security in
12 ea58dab1 2021-01-17 op mind: on Linux, FreeBSD and OpenBSD is sandboxed via `seccomp(2)`,
13 ea58dab1 2021-01-17 op `capsicum(4)`and `pledge(2)`+`unveil(2)` respectively.
18 4d2ec6d7 2021-01-13 op - IRI support (RFC3987)
19 b9220ca4 2021-01-11 op - dual stack: can serve over both IPv4 and IPv6
21 b9220ca4 2021-01-11 op - (very) low memory footprint
22 b9220ca4 2021-01-11 op - small codebase, easily hackable
23 b9220ca4 2021-01-11 op - virtual hosts
24 ea58dab1 2021-01-17 op - sandboxed by default on OpenBSD, Linux and FreeBSD
25 0b00962d 2021-01-25 op - chroot support
30 b9220ca4 2021-01-11 op - not suited for very busy hosts. If you receive an high number of
31 b9220ca4 2021-01-11 op connection per-second you'd probably want to run multiple gmid
32 b9220ca4 2021-01-11 op instances behind relayd/haproxy or a different server.
36 5f564d23 2021-01-17 op gmid depends on a POSIX libc and libtls (provided either by LibreSSL
37 5f564d23 2021-01-17 op or libretls). At build time, flex and yacc (or GNU bison) are also
40 771d8f28 2021-01-17 op The build is as simple as
44 8f0da580 2021-01-21 op If the configure scripts fails to pick up something, please open an
45 f980545b 2021-01-21 op issue or notify me via email.
47 771d8f28 2021-01-17 op To install execute:
51 17b09e3c 2021-01-18 op If you have trouble installing LibreSSL or libretls, as they aren't
52 17b09e3c 2021-01-18 op available as package on various Linux distribution, you can use Docker
53 17b09e3c 2021-01-18 op to build a `gmid` image with:
55 17b09e3c 2021-01-18 op docker build -t gmid .
57 17b09e3c 2021-01-18 op and then run it with something along the lines of
59 17b09e3c 2021-01-18 op docker run --rm -it -p 1965:1965 \
60 17b09e3c 2021-01-18 op -v /path/to/cert.pem:...:ro \
61 17b09e3c 2021-01-18 op -v /path/to/key.pem:...:ro \
62 17b09e3c 2021-01-18 op -v /path/to/docs:/var/gemini \
63 17b09e3c 2021-01-18 op gmid -f -d /var/gemini -K ... -C ...
65 17b09e3c 2021-01-18 op ellipses used for brevity.
67 dd8cc7d3 2021-01-22 op ### Local libretls
69 8f0da580 2021-01-21 op This is **NOT** recommended, please try to port LibreSSL/LibreTLS to
70 8f0da580 2021-01-21 op your distribution of choice or use docker instead.
72 8f0da580 2021-01-21 op However, it's possible to link `gmid` to locally-installed libtls
73 8f0da580 2021-01-21 op quite easily. (It's how I test gmid on Fedora, for instance)
75 04397b32 2021-01-21 op Let's say you have compiled and installed libretls in `$LIBRETLS`,
76 8f0da580 2021-01-21 op then you can build `gmid` with
78 04397b32 2021-01-21 op ./configure CFLAGS="-I$LIBRETLS/include" \
79 45b4aa6e 2021-01-23 op LDFLAGS="$LIBRETLS/lib/libtls.a -lssl -lcrypto -lpthread"
88 7f740a14 2021-01-22 op to start the suite. Keep in mind that the suite will create files
89 dd8cc7d3 2021-01-22 op inside the `regress` directory and bind the 10965 port.
92 881a9dd9 2021-01-16 op ## Architecture/Security considerations
94 881a9dd9 2021-01-16 op gmid is composed by two processes: a listener and an executor. The
95 881a9dd9 2021-01-16 op listener process is the only one that needs internet access and is
96 881a9dd9 2021-01-16 op sandboxed. When a CGI script needs to be executed, the executor
97 881a9dd9 2021-01-16 op (outside of the sandbox) sets up a pipe and gives one end to the
98 881a9dd9 2021-01-16 op listener, while the other is bound to the CGI script standard output.
99 881a9dd9 2021-01-16 op This way, is still possible to execute CGI scripts without restriction
100 15209ad9 2021-01-21 op even in the presence of a sandbox.
102 881a9dd9 2021-01-16 op On OpenBSD, the listener process runs with the `stdio recvfd rpath
103 881a9dd9 2021-01-16 op inet` pledges and has `unveil(2)`ed only the directories that it
104 ea58dab1 2021-01-17 op serves; the executor has `stdio sendfd proc exec` as pledges.
106 ea58dab1 2021-01-17 op On FreeBSD, the executor process is sandboxed with `capsicum(4)`.
108 76fd55f4 2021-01-17 op On Linux, a `seccomp(2)` filter is installed to allow only certain
109 76fd55f4 2021-01-17 op syscalls, see [sandbox.c](sandbox.c) for more information on the BPF
112 ea58dab1 2021-01-17 op In any case, you are invited to run gmid inside some sort of
113 0b00962d 2021-01-25 op container/jail/chroot.