jschoubben
d59649de0a
The mesh's resolver is more than config after all. Tools: dnsmasq_names (what this node answers, from the generated wildcard file) and dnsmasq_resolve (resolve a name through this node's own resolver — the check that wildcard-resolution actually answers). Event: it watches the wildcard file and emits module.dnsmasq.name.added/.removed as machines' names become resolvable here — DNS having propagated to this node, distinct from the mesh's node.* events. Typechecks; manifest parses.
60 lines
2.2 KiB
TypeScript
60 lines
2.2 KiB
TypeScript
// dnsmasq's own code, living in the module (novox/hq ADR 0044). dnsmasq here is a pure resolver: it
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// answers the mesh's generated wildcard names (<service>.<node>.<suffix>) and forwards nothing. So
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// its code reads what it was told to answer, and can resolve through itself to prove that it does.
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import { readFile } from "node:fs/promises";
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import { Resolver } from "node:dns/promises";
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export interface AnsweredName {
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/** A machine's internal name, e.g. "anchor.internal" — it and everything under it resolve here. */
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name: string;
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address: string;
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}
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export class DnsmasqClient {
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constructor(
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private readonly resolverPath: string,
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private readonly address: string,
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) {}
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/**
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* Build from the environment. Both values are node-local facts with mesh-chosen defaults — the
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* wildcard file the module is sent, and the loopback address its config listens on — so there is
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* nothing to be unconfigured about; it never throws.
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*/
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static fromEnv(env: NodeJS.ProcessEnv = process.env): DnsmasqClient {
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return new DnsmasqClient(
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env.MESH_DNSMASQ_RESOLVER_PATH ?? "/etc/mesh-resolver/nodes.conf",
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env.MESH_DNSMASQ_ADDRESS ?? "127.0.0.55",
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);
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}
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/** The names this resolver answers, read from the mesh-generated wildcard file. */
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async answeredNames(): Promise<AnsweredName[]> {
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let text: string;
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try {
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text = await readFile(this.resolverPath, "utf8");
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} catch {
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return []; // not yet on the network, or the file has not been written — no names, not an error
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}
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const names: AnsweredName[] = [];
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for (const line of text.split("\n")) {
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// dnsmasq wildcard syntax the mesh writes: address=/<node>.<suffix>/<address>
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const match = line.match(/^address=\/([^/]+)\/(.+)$/);
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if (match) names.push({ name: match[1], address: match[2] });
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}
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return names;
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}
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/** Resolve a name through this node's own resolver — the check that wildcard-resolution answers. */
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async resolve(name: string): Promise<string[]> {
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const resolver = new Resolver();
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resolver.setServers([this.address]);
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try {
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return await resolver.resolve4(name);
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} catch {
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return await resolver.resolve6(name);
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}
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}
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}
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