Initial commit

Generic SRV records checker for happyDomain.

For each SRV record attached to an svcs.UnknownSRV service, the checker
resolves every target and probes reachability:

  - DNS resolution (A/AAAA), CNAME detection (RFC 2782 violation),
    null-target detection (RFC 2782 "service explicitly unavailable")
  - TCP connect to target:port for _tcp SRVs
  - UDP probe for _udp SRVs, using ICMP port-unreachable detection

The checker also publishes TLS endpoints (host, port, SNI) for every
SRV target hitting a well-known direct-TLS port (443, 465, 636, 853,
993, 995, 5061, 5223, …) via the EndpointDiscoverer SDK interface, so
a downstream TLS checker can pick them up.

The HTML report groups records as cards and surfaces the most common
failure scenarios (DNS failure, CNAME target, TCP unreachable,
null-target) at the top with remediation guidance.

main.go

@@ -0,0 +1,24 @@
+// Command checker-srv is the standalone binary for the SRV checker.
+package main
+
+import (
+	"flag"
+	"log"
+
+	"git.happydns.org/checker-sdk-go/checker/server"
+	srv "git.happydns.org/checker-srv/checker"
+)
+
+var Version = "custom-build"
+
+var listenAddr = flag.String("listen", ":8080", "HTTP listen address")
+
+func main() {
+	flag.Parse()
+	srv.Version = Version
+
+	httpSrv := server.New(srv.Provider())
+	if err := httpSrv.ListenAndServe(*listenAddr); err != nil {
+		log.Fatalf("server error: %v", err)
+	}
+}