From a72df7a282b9e7a7df06468516e39acff206efd3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Florian=20H=C3=BCbner?= <code@hub.lol>
Date: Fri, 24 Nov 2023 18:57:54 +0100
Subject: [PATCH] generate hostname from mac addrs

---
 README.md         |  5 +++++
 build.sh          | 19 +++++++++++--------
 installer/late.sh | 17 +++++++++++++++++
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index d42f85f..30cda44 100644
--- a/README.md
+++ b/README.md
@@ -68,6 +68,11 @@ echo "ssh-ed25519 AAAA... bar" >> configs/authorized_keys
 
 If the `-p` flag is not set, a random admin password will be generated.
 
+### Hostname
+
+If the `-n` flag is not set, a hostname will be generated at installation.
+The hostname will be based on the installed machines mac addresses.
+
 ## Debug in VM
 
 While running the installer, press `ctrl`+`alt`+`f4` to show the installers log output.
diff --git a/build.sh b/build.sh
index 3e060b4..a59031a 100755
--- a/build.sh
+++ b/build.sh
@@ -22,8 +22,8 @@ usage() {
 username="janitor"
 password="$(pwgen -ns 16 1)"
 password_mask="false"
-hostname="machine"
-domain="example.org"
+hostname="undefined"
+domain="home.arpa"
 iso_url="https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-12.2.0-amd64-netinst.iso"
 sign_key="DA87E80D6294BE9B"
 out_file="debian-12.2.0-amd64-auto.iso"
@@ -85,17 +85,20 @@ cp -a installer/* "${workdir}"
 
 # generate password hash
 salt="$(pwgen -ns 16 1)"
-hash="$(mkpasswd -m sha-512 -S "${salt}" "${password}")"
+passhash="$(mkpasswd -m sha-512 -S "${salt}" "${password}")"
 if test "${password_mask}" == "true"; then
     password="$(echo "${password}" | tr '[:print:]' 'x')"
 fi
 
 # replace tokens
-find "${workdir}" -type f -exec sed -i "s#@USERNAME@#${username}#" {} \;
-sed -i "s#@PASSHASH@#${hash}#"        "${workdir}/preseed.cfg"
-sed -i "s#@HOSTNAME@#${hostname}#"    "${workdir}/preseed.cfg"
-sed -i "s#@DOMAIN@#${domain}#"        "${workdir}/preseed.cfg"
-sed -i "s#@PACKAGES@#${apt_pkgs[*]}#" "${workdir}/preseed.cfg"
+replace_token() {
+    find "${workdir}" -type f -exec sed -i "s#${1}#${2}#" {} \;
+}
+replace_token "@USERNAME@" "${username}"
+replace_token "@PASSHASH@" "${passhash}"
+replace_token "@HOSTNAME@" "${hostname}"
+replace_token "@DOMAIN@"   "${domain}"
+replace_token "@PACKAGES@" "${apt_pkgs[*]}"
 
 # clear existing output iso file
 if test -f "${out_file}"; then
diff --git a/installer/late.sh b/installer/late.sh
index 5170879..deef93d 100755
--- a/installer/late.sh
+++ b/installer/late.sh
@@ -4,6 +4,23 @@ set -eu
 
 prefix="/target"
 admin="@USERNAME@"
+hostname="@HOSTNAME@"
+domain="@DOMAIN@"
+
+if test "${hostname}" == "undefined"; then
+    # generate hostname from mac addresses
+    hostname="DEB$(cat /sys/class/net/*/address | tr -d '\n' | sha256sum | tr '[:lower:]' '[:upper:]' | head -c 5)"
+    echo "${hostname}" >"${prefix}/etc/hostname"
+    cat <<EOF >"${prefix}/etc/hosts"
+127.0.0.1	localhost
+127.0.1.1	${hostname}.${domain}	${hostname}
+
+# The following lines are desirable for IPv6 capable hosts
+::1     localhost ip6-localhost ip6-loopback
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+EOF
+fi
 
 # custom configs
 cp -a "/cdrom/configs/bashrc.bash" "${prefix}/etc/skel/.bashrc"