Pierre-Olivier Mercier
7e50f404a1
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.
64 lines
1.8 KiB
Go
64 lines
1.8 KiB
Go
//go:build standalone
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package checker
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import (
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"context"
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"fmt"
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"net"
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"strings"
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sdk "git.happydns.org/checker-sdk-go/checker"
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)
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// collectFallback queries DNS for SRV records directly when no upstream
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// service payload is available (standalone CLI/HTTP mode).
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func (p *srvProvider) collectFallback(ctx context.Context, opts sdk.CheckerOptions) (any, error) {
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subdomain, _ := sdk.GetOption[string](opts, "subdomain")
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domain, _ := sdk.GetOption[string](opts, "domain")
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serviceDomain := strings.TrimSuffix(subdomain, ".")
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if domain != "" {
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if serviceDomain != "" {
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serviceDomain += "." + strings.TrimSuffix(domain, ".")
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} else {
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serviceDomain = strings.TrimSuffix(domain, ".")
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}
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}
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if serviceDomain == "" {
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return nil, fmt.Errorf("missing 'domain' option")
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}
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// Empty service/proto tells the resolver to query the literal name as-is,
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// preserving _svc._proto labels already encoded in serviceDomain.
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_, srvs, err := net.DefaultResolver.LookupSRV(ctx, "", "", serviceDomain)
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if err != nil {
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return nil, fmt.Errorf("SRV lookup for %s: %w", serviceDomain, err)
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}
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if len(srvs) == 0 {
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return nil, fmt.Errorf("no SRV records at %s", serviceDomain)
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}
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tcpTimeout := durationOpt(opts, "tcpTimeout", 3000)
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udpTimeout := durationOpt(opts, "udpTimeout", 2000)
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svc, proto := parseOwner(serviceDomain, serviceDomain)
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data := &SRVData{
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ServiceDomain: serviceDomain,
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Records: make([]SRVRecord, 0, len(srvs)),
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}
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for _, s := range srvs {
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rec := SRVRecord{
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Service: svc,
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Proto: proto,
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Owner: serviceDomain,
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Target: strings.TrimSuffix(s.Target, "."),
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Port: s.Port,
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Priority: s.Priority,
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Weight: s.Weight,
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}
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resolveAndProbe(ctx, &rec, tcpTimeout, udpTimeout)
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data.Records = append(data.Records, rec)
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}
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return data, nil
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}
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