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.
107 lines
3.6 KiB
Go
107 lines
3.6 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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// Single-priority with multiple targets is Info (not Warn) because it is legal; all-zero-weight within a group is Warn because it almost always indicates a misconfiguration.
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type rulePriorityWeightSanity struct{}
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func RulePriorityWeightSanity() sdk.CheckRule { return &rulePriorityWeightSanity{} }
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func (rulePriorityWeightSanity) Name() string { return "srv_priority_weight_sanity" }
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func (rulePriorityWeightSanity) Description() string {
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return "Priority/weight values follow RFC 2782 conventions (failover present, weights meaningful)."
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}
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func (rulePriorityWeightSanity) 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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type groupKey struct{ owner string }
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type group struct {
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priorities map[uint16]int
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zeroWeight map[uint16]int
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}
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groups := map[groupKey]*group{}
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for _, r := range d.Records {
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if r.IsNullTarget {
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continue
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}
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k := groupKey{owner: r.Owner}
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g := groups[k]
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if g == nil {
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g = &group{priorities: map[uint16]int{}, zeroWeight: map[uint16]int{}}
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groups[k] = g
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}
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g.priorities[r.Priority]++
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if r.Weight == 0 {
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g.zeroWeight[r.Priority]++
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}
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}
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if len(groups) == 0 {
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return []sdk.CheckState{{Status: sdk.StatusInfo, Code: "srv_prio_weight_na",
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Message: "No active SRV records to analyse."}}
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}
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var noFailover []string
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var zeroWeightGroups []string
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for k, g := range groups {
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if len(g.priorities) < 2 {
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total := 0
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for _, c := range g.priorities {
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total += c
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}
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if total > 1 {
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noFailover = append(noFailover, k.owner)
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}
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}
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for prio, zc := range g.zeroWeight {
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if zc > 1 && zc == g.priorities[prio] {
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zeroWeightGroups = append(zeroWeightGroups, fmt.Sprintf("%s@prio=%d", k.owner, prio))
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}
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}
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}
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var out []sdk.CheckState
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if len(zeroWeightGroups) > 0 {
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out = append(out, sdk.CheckState{Status: sdk.StatusWarn, Code: "srv_weight_all_zero",
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Message: fmt.Sprintf("Priority group(s) with multiple targets all weighted 0: %s", strings.Join(zeroWeightGroups, ", "))})
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}
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if len(noFailover) > 0 {
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out = append(out, sdk.CheckState{Status: sdk.StatusInfo, Code: "srv_single_priority",
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Message: fmt.Sprintf("Service(s) with multiple records but a single priority tier (no failover): %s", strings.Join(noFailover, ", "))})
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}
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if len(out) == 0 {
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out = append(out, sdk.CheckState{Status: sdk.StatusOK, Code: "srv_prio_weight_ok",
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Message: "Priority and weight values are consistent with RFC 2782 conventions."})
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}
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return out
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}
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