metadata-api: support dnsmasq (#3115)

hack/qemu-metadata-api/dhcp/BUILD.bazel

@@ -0,0 +1,8 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "dhcp",
+    srcs = ["dhcp.go"],
+    importpath = "github.com/edgelesssys/constellation/v2/hack/qemu-metadata-api/dhcp",
+    visibility = ["//visibility:public"],
+)

hack/qemu-metadata-api/dhcp/dhcp.go

@@ -0,0 +1,13 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package dhcp
+
+// NetworkDHCPLease abstracts a DHCP lease.
+type NetworkDHCPLease struct {
+	IPaddr   string
+	Hostname string
+}

hack/qemu-metadata-api/dhcp/dnsmasq/BUILD.bazel

@@ -0,0 +1,24 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("//bazel/go:go_test.bzl", "go_test")
+
+go_library(
+    name = "dnsmasq",
+    srcs = ["dnsmasq.go"],
+    importpath = "github.com/edgelesssys/constellation/v2/hack/qemu-metadata-api/dhcp/dnsmasq",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//hack/qemu-metadata-api/dhcp",
+        "@com_github_spf13_afero//:afero",
+    ],
+)
+
+go_test(
+    name = "dnsmasq_test",
+    srcs = ["dnsmasq_test.go"],
+    embed = [":dnsmasq"],
+    deps = [
+        "@com_github_spf13_afero//:afero",
+        "@com_github_stretchr_testify//assert",
+        "@com_github_stretchr_testify//require",
+    ],
+)

hack/qemu-metadata-api/dhcp/dnsmasq/dnsmasq.go

@@ -0,0 +1,56 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package dnsmasq
+
+import (
+	"bufio"
+	"strings"
+
+	"github.com/edgelesssys/constellation/v2/hack/qemu-metadata-api/dhcp"
+	"github.com/spf13/afero"
+)
+
+// DNSMasq is a DHCP lease getter for dnsmasq.
+type DNSMasq struct {
+	leasesFileName string
+	fs             *afero.Afero
+}
+
+// New creates a new DNSMasq.
+func New(leasesFileName string) *DNSMasq {
+	return &DNSMasq{
+		leasesFileName: leasesFileName,
+		fs:             &afero.Afero{Fs: afero.NewOsFs()},
+	}
+}
+
+// GetDHCPLeases returns the underlying DHCP leases.
+func (d *DNSMasq) GetDHCPLeases() ([]dhcp.NetworkDHCPLease, error) {
+	file, err := d.fs.Open(d.leasesFileName)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	// read file
+	var leases []dhcp.NetworkDHCPLease
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+		// split by whitespace
+		fields := strings.Fields(line)
+		leases = append(leases, dhcp.NetworkDHCPLease{
+			IPaddr:   fields[2],
+			Hostname: fields[3],
+		})
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, err
+	}
+
+	return leases, nil
+}

hack/qemu-metadata-api/dhcp/dnsmasq/dnsmasq_test.go

@@ -0,0 +1,40 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package dnsmasq
+
+import (
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetDHCPLeases(t *testing.T) {
+	require := require.New(t)
+	assert := assert.New(t)
+
+	fs := afero.NewMemMapFs()
+	leasesFileName := "dnsmasq.leases"
+	leasesFile, err := fs.Create(leasesFileName)
+	require.NoError(err)
+	_, err = leasesFile.WriteString("1716219737 52:54:af:a1:98:9f 10.42.2.1 worker0 ff:c2:72:f6:09:00:02:00:00:ab:11:18:fc:48:85:40:3f:bc:41\n")
+	require.NoError(err)
+	_, err = leasesFile.WriteString("1716219735 52:54:7f:8f:ba:91 10.42.1.1 controlplane0 ff:c2:72:f6:09:00:02:00:00:ab:11:21:7c:b5:14:ec:43:b7:43\n")
+	require.NoError(err)
+	leasesFile.Close()
+
+	d := DNSMasq{leasesFileName: leasesFileName, fs: &afero.Afero{Fs: fs}}
+	leases, err := d.GetDHCPLeases()
+	require.NoError(err)
+
+	assert.Len(leases, 2)
+	assert.Equal("10.42.2.1", leases[0].IPaddr)
+	assert.Equal("worker0", leases[0].Hostname)
+	assert.Equal("10.42.1.1", leases[1].IPaddr)
+	assert.Equal("controlplane0", leases[1].Hostname)
+}

hack/qemu-metadata-api/dhcp/virtwrapper/BUILD.bazel

@@ -0,0 +1,16 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "virtwrapper",
+    srcs = [
+        "virtwrapper.go",
+        "virtwrapper_cgo.go",
+        "virtwrapper_cross.go",
+    ],
+    importpath = "github.com/edgelesssys/constellation/v2/hack/qemu-metadata-api/dhcp/virtwrapper",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//hack/qemu-metadata-api/dhcp",
+        "@org_libvirt_go_libvirt//:libvirt",
+    ],
+)

hack/qemu-metadata-api/dhcp/virtwrapper/virtwrapper.go

@@ -0,0 +1,7 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package virtwrapper

hack/qemu-metadata-api/dhcp/virtwrapper/virtwrapper_cgo.go

@@ -0,0 +1,60 @@
+//go:build cgo
+
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package virtwrapper
+
+import (
+	"github.com/edgelesssys/constellation/v2/hack/qemu-metadata-api/dhcp"
+
+	"libvirt.org/go/libvirt"
+)
+
+// Connect wraps a libvirt connection.
+type Connect struct {
+	conn        *libvirt.Connect
+	networkName string
+}
+
+// New creates a new libvirt Connct wrapper.
+func New(conn *libvirt.Connect, networkName string) *Connect {
+	return &Connect{
+		conn:        conn,
+		networkName: networkName,
+	}
+}
+
+// LookupNetworkByName looks up a network by name.
+func (c *Connect) lookupNetworkByName(name string) (*libvirt.Network, error) {
+	net, err := c.conn.LookupNetworkByName(name)
+	if err != nil {
+		return nil, err
+	}
+	return net, nil
+}
+
+// GetDHCPLeases returns the underlying DHCP leases.
+func (c *Connect) GetDHCPLeases() ([]dhcp.NetworkDHCPLease, error) {
+	net, err := c.lookupNetworkByName(c.networkName)
+	if err != nil {
+		return nil, err
+	}
+	defer net.Free()
+
+	leases, err := net.GetDHCPLeases()
+	if err != nil {
+		return nil, err
+	}
+	ret := make([]dhcp.NetworkDHCPLease, len(leases))
+	for i, l := range leases {
+		ret[i] = dhcp.NetworkDHCPLease{
+			IPaddr:   l.IPaddr,
+			Hostname: l.Hostname,
+		}
+	}
+	return ret, nil
+}

hack/qemu-metadata-api/dhcp/virtwrapper/virtwrapper_cross.go

@@ -0,0 +1,24 @@
+//go:build !cgo
+
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package virtwrapper
+
+import (
+	"errors"
+
+	"github.com/edgelesssys/constellation/v2/hack/qemu-metadata-api/dhcp"
+)
+
+// Connect wraps a libvirt connection.
+type Connect struct{}
+
+// GetDHCPLeases returns the underlying DHCP leases.
+// This function errors if CGO is disabled.
+func (n *Connect) GetDHCPLeases() ([]dhcp.NetworkDHCPLease, error) {
+	return nil, errors.New("using virtwrapper requires building with CGO")
+}