142 lines
5 KiB
Bash
Executable file
142 lines
5 KiB
Bash
Executable file
#!/bin/sh
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# mesh-hosts-render — render a static /etc/hosts block for the wg1 mesh from
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# data/mesh-hosts.json, and optionally splice it into /etc/hosts.
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#
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# For ROAMING / DNS-less clients (plum off-LAN, or any host before dnsmasq is
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# reachable). On-LAN hosts get the same names from dnsmasq; this static block is
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# the fallback that always works while the tunnel is up.
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#
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# Emits a marked, idempotently-replaceable block:
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# # >>> mesh-hosts (managed by smart-lan-router/bin/mesh-hosts-render)
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# 10.9.0.2 apricot.wg apricot
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# ...
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# # <<< mesh-hosts
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#
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# .wg names map to mesh IPs (always reachable via tunnel). .lan names map to LAN
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# IPs (home network only) for hosts that have a stable LAN IP. Roaming hosts
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# (lan == null) get no .lan record. The bare host name aliases the .wg view.
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#
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# Usage:
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# mesh-hosts-render # print the block to stdout (default; safe)
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# mesh-hosts-render --install # splice/replace the block in /etc/hosts (needs root)
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# mesh-hosts-render --diff # show what --install would change, no write
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#
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# Exit codes:
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# 0 success (printed, or installed, or already up to date)
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# 1 missing dependency / unlocatable or invalid JSON
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# 2 --install needs root but it isn't available
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set -eu
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mode=print
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case "${1:-}" in
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""|--print) mode=print ;;
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--install) mode=install ;;
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--diff) mode=diff ;;
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*) echo "mesh-hosts-render: unknown arg '$1' (use --print|--install|--diff)" >&2; exit 1 ;;
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esac
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BEGIN='# >>> mesh-hosts (managed by smart-lan-router/bin/mesh-hosts-render)'
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END='# <<< mesh-hosts'
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# Legacy block this tool replaces — stripped on install so its stale (drifted)
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# host entries don't shadow ours in first-match resolution.
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LEGACY_BEGIN='# >>> LAN hosts — managed by setup-lan-dns.sh'
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LEGACY_END='# <<< LAN hosts'
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HOSTS_FILE=/etc/hosts
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# --- locate data file, surviving symlink invocation ----------------------------
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self=$0
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while [ -L "$self" ]; do
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link=$(readlink "$self")
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case $link in
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/*) self=$link ;;
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*) self=$(dirname "$self")/$link ;;
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esac
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done
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root=$(cd "$(dirname "$self")" && pwd)
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while [ "$root" != "/" ] && [ ! -f "$root/data/mesh-hosts.json" ]; do
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root=$(dirname "$root")
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done
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data_file="$root/data/mesh-hosts.json"
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[ -f "$data_file" ] || { echo "mesh-hosts-render: cannot locate data/mesh-hosts.json (from $self)" >&2; exit 1; }
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command -v jq >/dev/null || { echo "mesh-hosts-render: jq not installed" >&2; exit 1; }
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jq empty "$data_file" || { echo "mesh-hosts-render: invalid JSON in $data_file" >&2; exit 1; }
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# Overlay: current LAN IPs discovered by the daemon (data/lan-state.json, a
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# {name: ip} map) override the static `lan` seed, so records track DHCP drift.
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overlay='{}'
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state_file="$root/data/lan-state.json"
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if [ -f "$state_file" ] && jq -e . "$state_file" >/dev/null 2>&1; then
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overlay=$(cat "$state_file")
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fi
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render_block() {
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printf '%s\n' "$BEGIN"
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printf '# Auto-generated from smart-lan-router/data/mesh-hosts.json — re-run to update.\n'
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printf '# .wg = mesh IP (anywhere via tunnel) · .lan = LAN IP (home network only)\n'
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# Mesh (.wg) records + bare-name alias to the mesh view.
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jq -r '
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.hosts[]
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| . as $h
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| "\($h.wg)\t" + (([($h.name + ".wg"), $h.name] + (($h.aliases // []) | map(. + ".wg") + .)) | join(" "))
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' "$data_file"
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# LAN (.lan) records — current discovered IP (overlay) wins over the static seed.
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jq -r --argjson ov "$overlay" '
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.hosts[]
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| . as $h
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| (($ov[$h.name]) // $h.lan) as $lan
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| select($lan != null)
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| "\($lan)\t\($h.name).lan"
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' "$data_file"
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printf '%s\n' "$END"
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}
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block=$(render_block)
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if [ "$mode" = "print" ]; then
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printf '%s\n' "$block"
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exit 0
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fi
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# Compute the new /etc/hosts: everything outside the markers, with our block
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# appended (or replaced in place if markers already exist).
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current=$(cat "$HOSTS_FILE" 2>/dev/null || true)
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stripped=$(printf '%s\n' "$current" | awk -v b="$BEGIN" -v e="$END" '
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$0 == b { skip = 1 }
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skip != 1 { print }
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$0 == e { skip = 0 }
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')
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# Trim trailing blank lines from the stripped body.
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stripped=$(printf '%s\n' "$stripped" | awk 'NF {p=NR} {l[NR]=$0} END {for(i=1;i<=p;i++) print l[i]}')
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# PREPEND our block so its records win /etc/hosts first-match resolution over any
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# other (e.g. a stale setup-lan-dns block that still lists a drifted apricot.lan).
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new=$(printf '%s\n\n%s\n' "$block" "$stripped")
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if [ "$mode" = "diff" ]; then
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if command -v diff >/dev/null 2>&1; then
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printf '%s\n' "$new" | diff -u "$HOSTS_FILE" - || true
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else
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printf '%s\n' "$new"
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fi
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exit 0
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fi
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# --install
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if printf '%s\n' "$new" | cmp -s - "$HOSTS_FILE"; then
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echo "mesh-hosts-render: $HOSTS_FILE already up to date"
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exit 0
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fi
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SUDO=
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if [ "$(id -u)" -ne 0 ]; then
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if command -v sudo >/dev/null 2>&1; then
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SUDO="sudo"
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else
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echo "mesh-hosts-render: --install needs root" >&2
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exit 2
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fi
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fi
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printf '%s\n' "$new" | $SUDO tee "$HOSTS_FILE" >/dev/null
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echo "mesh-hosts-render: updated $HOSTS_FILE"
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