Pierre-Olivier Mercier
90f1b4943f
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.
60 lines
2.2 KiB
Go
60 lines
2.2 KiB
Go
// This file is part of the happyDomain (R) project.
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// Copyright (c) 2020-2026 happyDomain
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// Authors: Pierre-Olivier Mercier, et al.
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//
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// This program is offered under a commercial and under the AGPL license.
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// For commercial licensing, contact us at <contact@happydomain.org>.
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//
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// For AGPL licensing:
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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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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"strings"
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sdk "git.happydns.org/checker-sdk-go/checker"
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)
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type ruleNullTarget struct{}
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func RuleNullTarget() sdk.CheckRule { return &ruleNullTarget{} }
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func (ruleNullTarget) Name() string { return "srv_null_target" }
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func (ruleNullTarget) Description() string {
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return "Detects SRV records with target \".\", which signals the service is intentionally not available."
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}
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func (ruleNullTarget) Evaluate(ctx context.Context, obs sdk.ObservationGetter, _ sdk.CheckerOptions) []sdk.CheckState {
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d, cs := getData(ctx, obs)
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if cs != nil {
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return []sdk.CheckState{*cs}
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}
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var nulls []string
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for _, r := range d.Records {
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if r.IsNullTarget {
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nulls = append(nulls, r.Owner)
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}
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}
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if len(nulls) == 0 {
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return []sdk.CheckState{{Status: sdk.StatusOK, Code: "srv_no_null",
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Message: "No null-target SRV records."}}
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}
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if len(nulls) == len(d.Records) {
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return []sdk.CheckState{{Status: sdk.StatusWarn, Code: "srv_all_null",
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Message: fmt.Sprintf("All %d SRV records use null target (\".\"): service explicitly disabled.", len(nulls))}}
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}
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return []sdk.CheckState{{Status: sdk.StatusInfo, Code: "srv_some_null",
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Message: fmt.Sprintf("%d record(s) have null target: %s", len(nulls), strings.Join(nulls, ", "))}}
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}
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