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
29 b9220ca4 2021-01-11 op - not suited for very busy hosts. If you receive an high number of
30 b9220ca4 2021-01-11 op connection per-second you'd probably want to run multiple gmid
31 b9220ca4 2021-01-11 op instances behind relayd/haproxy or a different server.
35 b9220ca4 2021-01-11 op gmid depends a POSIX libc and libtls. It can probably be linked
36 b9220ca4 2021-01-11 op against libretls, but I've never tried.
38 b9220ca4 2021-01-11 op See [INSTALL.gmi](INSTALL.gmi) for more info, but the build is as
43 b9220ca4 2021-01-11 op The Makefile isn't able to produce a statically linked executable
44 b9220ca4 2021-01-11 op (yet), so for that you have to execute by hand
47 b9220ca4 2021-01-11 op cc -static *.o /usr/lib/lib{crypto,tls,ssl}.a -o gmid
50 b9220ca4 2021-01-11 op to enjoy your ~2.3M statically-linked gmid.
53 881a9dd9 2021-01-16 op ## Architecture/Security considerations
55 881a9dd9 2021-01-16 op gmid is composed by two processes: a listener and an executor. The
56 881a9dd9 2021-01-16 op listener process is the only one that needs internet access and is
57 881a9dd9 2021-01-16 op sandboxed. When a CGI script needs to be executed, the executor
58 881a9dd9 2021-01-16 op (outside of the sandbox) sets up a pipe and gives one end to the
59 881a9dd9 2021-01-16 op listener, while the other is bound to the CGI script standard output.
60 881a9dd9 2021-01-16 op This way, is still possible to execute CGI scripts without restriction
61 881a9dd9 2021-01-16 op even if the presence of a sandbox.
63 881a9dd9 2021-01-16 op On OpenBSD, the listener process runs with the `stdio recvfd rpath
64 881a9dd9 2021-01-16 op inet` pledges and has `unveil(2)`ed only the directories that it
65 ea58dab1 2021-01-17 op serves; the executor has `stdio sendfd proc exec` as pledges.
67 ea58dab1 2021-01-17 op On FreeBSD, the executor process is sandboxed with `capsicum(4)`.
69 76fd55f4 2021-01-17 op On Linux, a `seccomp(2)` filter is installed to allow only certain
70 76fd55f4 2021-01-17 op syscalls, see [sandbox.c](sandbox.c) for more information on the BPF
73 ea58dab1 2021-01-17 op In any case, you are invited to run gmid inside some sort of
74 ea58dab1 2021-01-17 op container/jail.