From 1719b8a036356c08bac8c934997cac2d2716dbbd Mon Sep 17 00:00:00 2001
From: Arun Isaac
Date: Fri, 6 Oct 2023 13:34:40 +0100
Subject: Provide G-expression script for UTHSC VPN.

* topics/uthsc-vpn-with-free-software.gmi (Putting it all together
using Guix G-expressions): New section.
* topics/uthsc-vpn.scm: New file.
* tissue.scm (#:web-files): Publish scm files.
---
 tissue.scm                              |  3 ++-
 topics/uthsc-vpn-with-free-software.gmi |  9 +++++++
 topics/uthsc-vpn.scm                    | 44 +++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 topics/uthsc-vpn.scm

diff --git a/tissue.scm b/tissue.scm
index 645a84b..bdeac24 100644
--- a/tissue.scm
+++ b/tissue.scm
@@ -62,7 +62,8 @@
                                                             #:engine %engine)))
                                    ((or (string-suffix? ".jpg" filename)
                                         (string-suffix? ".png" filename)
-                                        (string-suffix? ".svg" filename))
+                                        (string-suffix? ".svg" filename)
+                                        (string-suffix? ".scm" filename))
                                     (file filename
                                           (copier filename)))
                                    (else #f)))
diff --git a/topics/uthsc-vpn-with-free-software.gmi b/topics/uthsc-vpn-with-free-software.gmi
index 5288101..34c9901 100644
--- a/topics/uthsc-vpn-with-free-software.gmi
+++ b/topics/uthsc-vpn-with-free-software.gmi
@@ -44,6 +44,15 @@ export OPENSSL_CONF=/tmp/openssl.cnf
 ```
 Then, run the openconnect-sso client as usual.
 
+## Putting it all together using Guix G-expressions
+
+Remembering to do all these steps is a hassle. Writing a shell script to automate this is a good idea, but why write shell scripts when we have G-expressions! Here's a G-expression that I prepared earlier.
+=> uthsc-vpn.scm
+Download it, tweak the %hosts variable to specify the hosts you are interested in, and run it like so:
+```
+$(guix build -f uthsc-vpn.scm)
+```
+
 ## Acknowledgement
 
 Many thanks to Pjotr Prins and Erik Garrison without whose earlier work this guide would not be possible.
diff --git a/topics/uthsc-vpn.scm b/topics/uthsc-vpn.scm
new file mode 100644
index 0000000..c714731
--- /dev/null
+++ b/topics/uthsc-vpn.scm
@@ -0,0 +1,44 @@
+(use-modules ((gnu packages guile-xyz) #:select (guile-ini guile-lib guile-smc))
+             ((gnu packages vpn) #:select (openconnect-sso vpn-slice))
+             (guix gexp))
+
+;; Put in the hosts you are interested in here.
+(define %hosts
+  (list "octopus01"
+        "tux01.genenetwork.org"))
+
+(define (ini-file name scm)
+  "Return a file-like object representing INI file with @var{name} and
+@var{scm} data."
+  (computed-file name
+                 (with-extensions (list guile-ini guile-lib guile-smc)
+                   #~(begin
+                       (use-modules (srfi srfi-26)
+                                    (ini))
+
+                       (call-with-output-file #$output
+                         (cut scm->ini #$scm #:port <>))))))
+
+(define uthsc-vpn
+  (with-imported-modules '((guix build utils))
+    #~(begin
+        (use-modules (guix build utils))
+
+        (setenv "OPENSSL_CONF"
+                #$(ini-file "openssl.cnf"
+                            #~'((#f
+                                 ("openssl_conf" . "openssl_init"))
+                                ("openssl_init"
+                                 ("ssl_conf" . "ssl_sect"))
+                                ("ssl_sect"
+                                 ("system_default" . "system_default_sect"))
+                                ("system_default_sect"
+                                 ("Options" . "UnsafeLegacyRenegotiation")))))
+        (invoke #$(file-append openconnect-sso "/bin/openconnect-sso")
+                "--server" "uthscvpn1.uthsc.edu"
+                "--authgroup" "UTHSC"
+                "--"
+                "--script" (string-join (cons #$(file-append vpn-slice "/bin/vpn-slice")
+                                              '#$%hosts))))))
+
+(program-file "uthsc-vpn" uthsc-vpn)
-- 
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