feat: DNS checker，自研 codec/transport，支持 system/server 双模式，UDP/TCP + TC fallback

tests/server/checker/runner/detail.test.ts

@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test";
 
 import { CommandChecker } from "../../../../src/server/checker/runner/cmd/execute";
 import { DbChecker } from "../../../../src/server/checker/runner/db/execute";
+import { DnsChecker } from "../../../../src/server/checker/runner/dns/execute";
 import { HttpChecker } from "../../../../src/server/checker/runner/http/execute";
 import { IcmpChecker } from "../../../../src/server/checker/runner/icmp/execute";
 import { LlmChecker } from "../../../../src/server/checker/runner/llm/execute";
@@ -64,4 +65,142 @@ describe("Checker buildDetail", () => {
     expect(detail).toContain("output=2 chars");
     expect(detail).toContain("usage=12/2 tokens");
   });
+
+  const dnsChecker = new DnsChecker();
+
+  test("DnsChecker system mode: successful resolution shows addresses and duration", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 15,
+      error: null,
+      family: "any",
+      name: "example.com",
+      resolver: "system",
+      valueCount: 2,
+      values: ["93.184.216.34", "93.184.216.35"],
+    });
+    expect(detail).toContain("93.184.216.34");
+    expect(detail).toContain("15ms");
+  });
+
+  test("DnsChecker system mode: failed resolution shows error", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 100,
+      error: "getaddrinfo ENOTFOUND",
+      family: "any",
+      name: "example.com",
+      resolver: "system",
+      valueCount: 0,
+      values: [],
+    });
+    expect(detail).toContain("解析失败");
+    expect(detail).toContain("getaddrinfo ENOTFOUND");
+  });
+
+  test("DnsChecker system mode: no results shows '解析成功但无结果'", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 10,
+      error: null,
+      family: "any",
+      name: "example.com",
+      resolver: "system",
+      valueCount: 0,
+      values: [],
+    });
+    expect(detail).toContain("解析成功但无结果");
+  });
+
+  test("DnsChecker server mode: successful response shows rcode, values, protocol, duration", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 25,
+      error: null,
+      name: "example.com",
+      port: 53,
+      protocol: "udp",
+      protocolUsed: "udp",
+      rcode: "NOERROR",
+      recordType: "A",
+      resolver: "server",
+      responded: true,
+      server: "8.8.8.8",
+      valueCount: 2,
+      values: ["1.1.1.1", "2.2.2.2"],
+    });
+    expect(detail).toContain("NOERROR");
+    expect(detail).toContain("1.1.1.1");
+    expect(detail).toContain("UDP");
+    expect(detail).toContain("25ms");
+  });
+
+  test("DnsChecker server mode: NXDOMAIN shows rcode", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 30,
+      error: null,
+      name: "example.com",
+      port: 53,
+      protocol: "udp",
+      protocolUsed: "udp",
+      rcode: "NXDOMAIN",
+      recordType: "A",
+      resolver: "server",
+      responded: true,
+      server: "8.8.8.8",
+      valueCount: 0,
+      values: [],
+    });
+    expect(detail).toContain("NXDOMAIN");
+  });
+
+  test("DnsChecker server mode: no response shows error", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 500,
+      error: "探测超时",
+      name: "example.com",
+      port: 53,
+      protocol: "udp",
+      resolver: "server",
+      responded: false,
+      server: "8.8.8.8",
+    });
+    expect(detail).toContain("查询失败");
+    expect(detail).toContain("探测超时");
+  });
+
+  test("DnsChecker server mode: CNAME chain shows CNAME chain", () => {
+    const detail = dnsChecker.buildDetail({
+      cnameChain: ["cdn.example.com", "cdn-edge.example.net"],
+      durationMs: 40,
+      error: null,
+      name: "example.com",
+      port: 53,
+      protocol: "udp",
+      protocolUsed: "udp",
+      rcode: "NOERROR",
+      recordType: "A",
+      resolver: "server",
+      responded: true,
+      server: "8.8.8.8",
+      valueCount: 1,
+      values: ["93.184.216.34"],
+    });
+    expect(detail).toContain("CNAME: cdn.example.com → cdn-edge.example.net");
+  });
+
+  test("DnsChecker server mode: TCP fallback shows TCP in output", () => {
+    const detail = dnsChecker.buildDetail({
+      durationMs: 50,
+      error: null,
+      name: "example.com",
+      port: 53,
+      protocol: "udp",
+      protocolUsed: "tcp",
+      rcode: "NOERROR",
+      recordType: "A",
+      resolver: "server",
+      responded: true,
+      server: "8.8.8.8",
+      valueCount: 1,
+      values: ["1.2.3.4"],
+    });
+    expect(detail).toContain("TCP");
+  });
 });