jochen
0f6986aead
During the 2026-10-09 outage the control node's resolver stayed active while it no longer listened on its private address, and nothing on the mesh could ask that address a question or show which sockets were bound. netcheck_dns takes server (and tcp) to ask one resolver alone and say its response code; netcheck_listening reads the kernel's socket tables, as ss -lunt does, with the owning program where the tool's account may see it and a sentence where it may not.
103 lines
3.9 KiB
Go
103 lines
3.9 KiB
Go
// netcheck's Go tools bundle (novox/hq ADR 0188, ADR 0193): a process the node's runtime launches
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// and speaks MCP over stdio to, through the Go SDK. It serves the two checks that are the machine's
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// own sockets and resolver — a TCP connect, a DNS lookup (of the machine's resolver, or of one named),
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// and what listens here — and nothing that changes anything.
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// The module's HTTP check is its TypeScript bundle; the runtime serves both under one module.
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package main
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import (
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"fmt"
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"os"
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"strings"
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stdio "git.novox.be/novox/mesh-sdk/go"
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)
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func main() {
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// An empty name serves as the module the runtime names (MESH_SERVED_MODULE): netcheck.
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if err := stdio.Serve("", tools()); err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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}
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func tools() []stdio.Tool {
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return []stdio.Tool{
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{
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Name: "netcheck_listening",
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Description: "What listens on this machine: every TCP socket in the listen state and every bound UDP socket, " +
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"from the kernel's own tables (what ss -lunt reads), with the program holding it where this tool may see it. " +
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"port narrows it to one port, e.g. 53 to see on which addresses the resolver answers.",
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Input: map[string]any{
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"port": map[string]any{"type": "integer", "description": "only this port (default every port)"},
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},
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Run: func(args map[string]any) (any, error) {
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port := 0
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if _, given := args["port"]; given {
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p, err := whole(args, "port", 0)
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if err != nil {
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return nil, err
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}
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if p < 1 || p > 65535 {
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return nil, fmt.Errorf("port %d is not a port (1-65535)", p)
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}
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port = p
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}
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return Listening("/proc", port), nil
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},
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},
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{
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Name: "netcheck_tcp",
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Description: "Check whether a TCP port is reachable from this machine: opens one connection " +
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"and closes it at once, sending nothing. Answers reachable, elapsed_ms and the error when not.",
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Input: map[string]any{
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"host": map[string]any{"type": "string", "description": "host name or IP address"},
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"port": map[string]any{"type": "integer", "description": "TCP port, 1-65535"},
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"timeout_ms": map[string]any{"type": "integer", "description": "give up after this long (default 3000, at most 30000)"},
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},
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Run: func(args map[string]any) (any, error) {
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host, err := text(args, "host")
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if err != nil {
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return nil, err
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}
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port, err := whole(args, "port", 0)
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if err != nil {
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return nil, err
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}
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timeout, err := timeoutOf(args)
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if err != nil {
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return nil, err
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}
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return CheckTCP(host, port, timeout)
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},
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},
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{
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Name: "netcheck_dns",
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Description: "Look a name up with this machine's resolver (its /etc/resolv.conf and /etc/hosts), or — with server — ask " +
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"that one resolver alone over UDP (or TCP), answering its response code (NOERROR, NXDOMAIN, REFUSED…). " +
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"type is A, AAAA, CNAME, TXT or MX; answers the records found, or the error.",
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Input: map[string]any{
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"name": map[string]any{"type": "string", "description": "the name to look up"},
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"type": map[string]any{"type": "string", "enum": []string{"A", "AAAA", "CNAME", "TXT", "MX"}, "description": "record type (default A)"},
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"server": map[string]any{"type": "string", "description": "ask this resolver alone: an address, with :port or without (53), e.g. 10.10.0.1"},
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"tcp": map[string]any{"type": "boolean", "description": "ask the server over TCP rather than UDP (default false)"},
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"timeout_ms": map[string]any{"type": "integer", "description": "give up after this long (default 3000, at most 30000)"},
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},
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Run: func(args map[string]any) (any, error) {
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name, err := text(args, "name")
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if err != nil {
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return nil, err
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}
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kind, _ := args["type"].(string)
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timeout, err := timeoutOf(args)
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if err != nil {
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return nil, err
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}
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server, _ := args["server"].(string)
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overTCP, _ := args["tcp"].(bool)
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return AskDNS(name, kind, strings.TrimSpace(server), overTCP, timeout)
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},
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},
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}
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}
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