Initial version

.github/dependabot.yml

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+version: 2
+updates:
+- package-ecosystem: github-actions
+  directory: "/"
+  schedule:
+    interval: daily
+    timezone: Europe/Copenhagen
+  assignees:
+  - arnested
+- package-ecosystem: gomod
+  directory: "/"
+  schedule:
+    interval: daily
+    timezone: Europe/Copenhagen
+  assignees:
+  - arnested

.github/workflows/bump-version.yml

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+name: Bump version
+on:
+  push:
+    branches:
+    - main
+jobs:
+  bump-version:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 0
+    - name: Bump version and push tag
+      uses: anothrNick/github-tag-action@1.33.0
+      id: version
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        WITH_V: true
+        DEFAULT_BUMP: patch
+    - name: Create release
+      if: ${{ steps.version.outputs.new_tag }} != ""
+      uses: actions/create-release@v1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        tag_name: ${{ steps.version.outputs.new_tag }}
+        release_name: Release ${{ steps.version.outputs.new_tag }}
+        draft: false
+        prerelease: false

.github/workflows/codeql-analysis.yml

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+name: "CodeQL"
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [main]
+  schedule:
+    - cron: '0 2 * * 5'
+
+jobs:
+  analyse:
+    name: Analyse
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+      with:
+        # We must fetch at least the immediate parents so that if this is
+        # a pull request then we can checkout the head.
+        fetch-depth: 2
+
+    # If this run was triggered by a pull request event, then checkout
+    # the head of the pull request instead of the merge commit.
+    - run: git checkout HEAD^2
+      if: ${{ github.event_name == 'pull_request' }}
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v1
+      with:
+        languages: go
+
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v1
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v1

.github/workflows/golangci-lint.yml

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+name: golangci-lint
+on:
+  pull_request:
+jobs:
+  golangci:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v2
+        with:
+          version: latest
+          only-new-issues: true

.github/workflows/push.yml

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+on: push
+name: Build and test
+jobs:
+  go_generate:
+    name: Check generated code is up to date
+    if: '!github.event.deleted'
+    runs-on: ubuntu-latest
+    env:
+      workdir: go/src/arnested.dk/go/ldddns
+    steps:
+    - uses: actions/checkout@v2.3.1
+      with:
+        path: ${{env.workdir}}
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: '1.15'
+    - name: go generate
+      env:
+        GO111MODULE: 'on'
+        GOPATH: ${{ github.workspace }}/go
+      working-directory: ${{env.workdir}}
+      run: go generate -x
+    - name: Diff after go generate
+      working-directory: ${{env.workdir}}
+      run: git diff --exit-code
+  build_and_test:
+    name: Build and test
+    if: '!github.event.deleted'
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: ['1.15']
+    steps:
+    - uses: actions/checkout@v2.3.1
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: ${{ matrix.go-version }}
+    - name: go test
+      env:
+        GO111MODULE: 'on'
+      run: go test -v -race -cover -covermode=atomic -coverprofile=coverage.txt ./...
+    - name: Upload coverage report to Codecov
+      uses: codecov/codecov-action@v1.1.0
+      with:
+        flags: go${{ matrix.go-version }}
+        token: ${{secrets.CODECOV_TOKEN}}
+  license_check:
+    name: License check
+    if: '!github.event.deleted'
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2.3.1
+    - name: Install Go
+      uses: actions/setup-go@v2
+      with:
+        go-version: '1.15'
+    - name: Install wwhrd
+      env:
+        GO111MODULE: 'off'
+      run: go get -u github.com/frapposelli/wwhrd
+    - name: go mod vendor
+      env:
+        GO111MODULE: 'on'
+      run: go mod vendor
+    - name: wwhrd check
+      run: wwhrd check

.gitignore

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+/ldddns

.wwhrd.yml

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+---
+whitelist:
+  - MIT
+  - Apache-2.0
+  - BSD-2-Clause
+  - BSD-3-Clause
+  - CC-BY-SA-4.0
+
+exceptions:
+  - github.com/gogo/protobuf/proto

container.go

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+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"strconv"
+	"strings"
+
+	"github.com/docker/docker/api/types"
+	"honnef.co/go/netdb"
+)
+
+func handleContainer(
+	ctx context.Context,
+	container types.ContainerJSON,
+	egs *EntryGroups,
+	status string,
+) {
+	eg, commit, err := egs.Get(container.ID)
+	defer commit()
+
+	if err != nil {
+		panic(fmt.Errorf("cannot get entry group for container %q: %w", container.ID, err))
+	}
+
+	empty, _ := eg.IsEmpty()
+	if !empty {
+		_ = eg.Reset()
+	}
+
+	if status == "die" || status == "kill" || status == "pause" {
+		return
+	}
+
+	ips := extractIPNumbers(ctx, container)
+	if len(ips) == 0 {
+		return
+	}
+
+	hostname := extractHostname(ctx, container)
+	if hostname == "" {
+		return
+	}
+
+	services := extractServices(ctx, container)
+
+	hostname = rewriteHostname(ctx, hostname)
+
+	addToDNS(eg, hostname, ips, services)
+}
+
+// extractIPnumbers from a container.
+func extractIPNumbers(_ context.Context, container types.ContainerJSON) []string {
+	ips := []string{}
+
+	if container.NetworkSettings.IPAddress != "" {
+		ips = append(ips, container.NetworkSettings.IPAddress)
+	}
+
+	for _, v := range container.NetworkSettings.Networks {
+		ips = append(ips, v.IPAddress)
+	}
+
+	return ips
+}
+
+// extractServices from a container.
+func extractServices(_ context.Context, container types.ContainerJSON) map[string]uint16 {
+	services := map[string]uint16{}
+
+	for k := range container.NetworkSettings.Ports {
+		port := strings.SplitN(string(k), "/", 2)
+
+		proto := netdb.GetProtoByName(port[1])
+
+		portNumber, err := strconv.Atoi(port[0])
+		if err != nil {
+			log.Printf("Could not get port number from %q", k)
+
+			continue
+		}
+
+		service := netdb.GetServByPort(portNumber, proto)
+
+		if service == nil || proto == nil {
+			continue
+		}
+
+		services[fmt.Sprintf("_%s._%s", service.Name, proto.Name)] = uint16(portNumber)
+	}
+
+	return services
+}
+
+// extractHostname from a container.
+func extractHostname(_ context.Context, container types.ContainerJSON) string {
+	for _, v := range container.Config.Env {
+		if strings.HasPrefix(v, "VIRTUAL_HOST=") {
+			return v[13:]
+		}
+	}
+
+	return ""
+}

dns.go

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+package main
+
+import (
+	"fmt"
+
+	"github.com/holoplot/go-avahi"
+)
+
+func addToDNS(eg *avahi.EntryGroup, hostname string, ips []string, services map[string]uint16) {
+	if hostname == "" {
+		return
+	}
+
+	for _, ip := range ips {
+		if ip == "" {
+			continue
+		}
+
+		err := eg.AddAddress(avahi.InterfaceUnspec, avahi.ProtoUnspec, 0, hostname, ip)
+		if err != nil {
+			panic(fmt.Errorf("AddAddess() failed: %w", err))
+		}
+
+		logf(PriDebug, "added address for %q pointing to %q", hostname, ip)
+
+		for service, portNumber := range services {
+			err = eg.AddService(
+				avahi.InterfaceUnspec,
+				avahi.ProtoUnspec,
+				0,
+				hostname,
+				service,
+				"local",
+				hostname,
+				portNumber,
+				nil,
+			)
+			if err != nil {
+				panic(fmt.Errorf("AddService() failed: %w", err))
+			}
+		}
+	}
+}

entry_groups.go

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+package main
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/holoplot/go-avahi"
+)
+
+type EntryGroups struct {
+	avahiServer *avahi.Server
+	groups      map[string]*avahi.EntryGroup
+	mutex       sync.Mutex
+}
+
+func NewEntryGroups(avahiServer *avahi.Server) *EntryGroups {
+	return &EntryGroups{
+		avahiServer: avahiServer,
+		groups:      make(map[string]*avahi.EntryGroup),
+	}
+}
+
+func (e *EntryGroups) Get(containerID string) (*avahi.EntryGroup, func(), error) {
+	commit := func() {
+		empty, _ := e.groups[containerID].IsEmpty()
+		if !empty {
+			err := e.groups[containerID].Commit()
+			if err != nil {
+				logf(PriErr, "error committing: %v\n", err)
+			}
+		}
+
+		e.mutex.Unlock()
+	}
+
+	e.mutex.Lock()
+	if _, ok := e.groups[containerID]; !ok {
+		eg, err := e.avahiServer.EntryGroupNew()
+		if err != nil {
+			return nil, commit, fmt.Errorf("error creating new entry group: %w", err)
+		}
+
+		e.groups[containerID] = eg
+	}
+
+	return e.groups[containerID], commit, nil
+}