From b29e32df30f5cfed250a347cc63c147d13b65a90 Mon Sep 17 00:00:00 2001
From: "Dustin C. Hatch" <dustin@hatch.name>
Date: Sat, 12 Mar 2022 16:23:18 -0600
Subject: [PATCH] rootfs: Get syslog servers from DHCP options

Instead of parsing the kernel command line to find the destination(s)
where syslog messages should be forwarded, we can use a *dhcpcd* hook to
get them from the DHCP lease.
---
 cmdline.txt                                   |  2 +-
 rootfs/overlay/etc/dhcpcd.conf                |  2 ++
 .../usr/lib/dhcpcd/dhcpcd-hooks/60-syslog     | 28 +++++++++++++++++++
 .../systemd/system/gen-rsyslog-conf.service   |  7 -----
 .../after-network-online.conf                 |  2 ++
 .../gen-rsyslog-conf.service                  |  1 -
 .../overlay/usr/libexec/gen-rsyslog-conf.sh   | 12 --------
 7 files changed, 33 insertions(+), 21 deletions(-)
 create mode 100644 rootfs/overlay/usr/lib/dhcpcd/dhcpcd-hooks/60-syslog
 delete mode 100644 rootfs/overlay/usr/lib/systemd/system/gen-rsyslog-conf.service
 create mode 100644 rootfs/overlay/usr/lib/systemd/system/rsyslog.service.d/after-network-online.conf
 delete mode 120000 rootfs/overlay/usr/lib/systemd/system/rsyslog.service.wants/gen-rsyslog-conf.service
 delete mode 100755 rootfs/overlay/usr/libexec/gen-rsyslog-conf.sh

diff --git a/cmdline.txt b/cmdline.txt
index 21320e6..32d518e 100644
--- a/cmdline.txt
+++ b/cmdline.txt
@@ -1 +1 @@
-audit=0 panic=5 console=ttyAMA0 root=nbd:rosalina.pyrocufflink.blue:jenkinsagent rsyslog.dest=rosalina.pyrocufflink.blue sshkeys.root=http://rosalina.pyrocufflink.blue/~dustin/id_ed25519.pub
+audit=0 panic=5 console=ttyAMA0 root=nbd:rosalina.pyrocufflink.blue:jenkinsagent sshkeys.root=http://rosalina.pyrocufflink.blue/~dustin/id_ed25519.pub
diff --git a/rootfs/overlay/etc/dhcpcd.conf b/rootfs/overlay/etc/dhcpcd.conf
index 7ee8c1a..e61eec7 100644
--- a/rootfs/overlay/etc/dhcpcd.conf
+++ b/rootfs/overlay/etc/dhcpcd.conf
@@ -39,6 +39,8 @@ option ntp_servers
 # on the server to actually work.
 option rapid_commit
 
+option log_servers
+
 # A ServerID is required by RFC2131.
 require dhcp_server_identifier
 
diff --git a/rootfs/overlay/usr/lib/dhcpcd/dhcpcd-hooks/60-syslog b/rootfs/overlay/usr/lib/dhcpcd/dhcpcd-hooks/60-syslog
new file mode 100644
index 0000000..f377917
--- /dev/null
+++ b/rootfs/overlay/usr/lib/dhcpcd/dhcpcd-hooks/60-syslog
@@ -0,0 +1,28 @@
+#!/bin/sh
+
+gen_action() {
+    echo   'action('
+    echo   '    type="omfwd"'
+    printf '    Target="%s"\n' "${1}"
+    echo   '    Port="514"'
+    echo   '    template="RSYSLOG_SyslogProtocol23Format"'
+    echo   ')'
+}
+
+changed=false
+if [ -n "${interface}" ] && [ -d /run/rsyslog.d ]; then
+    if [ -n "${new_log_servers}" ]; then
+        echo '# Generated by dhcpcd' > /run/rsyslog.d/dhcpcd."${interface}".conf
+        for s in ${new_log_servers}; do
+            gen_action "${s}" >> /run/rsyslog.d/dhcpcd."${interface}".conf
+        done
+        changed=true
+    elif [ -n "${old_log_servers}" ]; then
+        rm -f /run/rsyslog.d/dhcpcd."${interface}".conf
+        changed=true
+    fi
+fi
+
+if ${changed}; then
+    systemctl try-restart rsyslog
+fi
diff --git a/rootfs/overlay/usr/lib/systemd/system/gen-rsyslog-conf.service b/rootfs/overlay/usr/lib/systemd/system/gen-rsyslog-conf.service
deleted file mode 100644
index 62081b2..0000000
--- a/rootfs/overlay/usr/lib/systemd/system/gen-rsyslog-conf.service
+++ /dev/null
@@ -1,7 +0,0 @@
-[Unit]
-Description=Generate rsyslog.conf
-Before=rsyslog.service
-
-[Service]
-Type=oneshot
-ExecStart=/usr/libexec/gen-rsyslog-conf.sh
diff --git a/rootfs/overlay/usr/lib/systemd/system/rsyslog.service.d/after-network-online.conf b/rootfs/overlay/usr/lib/systemd/system/rsyslog.service.d/after-network-online.conf
new file mode 100644
index 0000000..758b827
--- /dev/null
+++ b/rootfs/overlay/usr/lib/systemd/system/rsyslog.service.d/after-network-online.conf
@@ -0,0 +1,2 @@
+[Unit]
+After=network-online.target
diff --git a/rootfs/overlay/usr/lib/systemd/system/rsyslog.service.wants/gen-rsyslog-conf.service b/rootfs/overlay/usr/lib/systemd/system/rsyslog.service.wants/gen-rsyslog-conf.service
deleted file mode 120000
index d670be7..0000000
--- a/rootfs/overlay/usr/lib/systemd/system/rsyslog.service.wants/gen-rsyslog-conf.service
+++ /dev/null
@@ -1 +0,0 @@
-../gen-rsyslog-conf.service
\ No newline at end of file
diff --git a/rootfs/overlay/usr/libexec/gen-rsyslog-conf.sh b/rootfs/overlay/usr/libexec/gen-rsyslog-conf.sh
deleted file mode 100755
index 340a0e1..0000000
--- a/rootfs/overlay/usr/libexec/gen-rsyslog-conf.sh
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/bin/sh -e
-
-# shellcheck disable=SC2046
-set -- $(cat /proc/cmdline)
-while [ $# -ge 1 ]; do
-    case "$1" in
-    rsyslog.dest=*)
-        printf '*.* @%s\n' "${1#*=}" >> /run/rsyslog.d/remote.conf
-        ;;
-    esac
-    shift
-done