Merge branch 'main' into update-contributors

.golangci.yaml

@@ -48,6 +48,7 @@ linters-settings:
       - ip
       - ok
       - c
+      - tt
 
   gocritic:
     disabled-checks:

CHANGELOG.md

@@ -2,6 +2,24 @@
 
 **TBD (TBD):**
 
+**0.14.0 (2022-xx-xx):**
+
+**UPCOMING BREAKING**:
+From the **next** version (`0.15.0`), all machines will be able to communicate regardless of
+if they are in the same namespace. This means that the behaviour currently limited to ACLs
+will become default. From version `0.15.0`, all limitation of communications must be done
+with ACLs.
+
+This is a part of aligning `headscale`'s behaviour with Tailscale's upstream behaviour.
+
+**BREAKING**:
+
+- ACLs have been rewritten to align with the bevaviour Tailscale Control Panel provides. **NOTE:** This is only active if you use ACLs
+  - Namespaces are now treated as Users
+  - All machines can communicate with all machines by default
+  - Tags should now work correctly and adding a host to Headscale should now reload the rules.
+  - The documentation have a [fictional example](docs/acls.md) that should cover some use cases of the ACLs features
+
 **0.13.0 (2022-02-18):**
 
 **Features**:

acls.go

@@ -20,7 +20,6 @@ const (
 	errInvalidUserSection = Error("invalid user section")
 	errInvalidGroup       = Error("invalid group")
 	errInvalidTag         = Error("invalid tag")
-	errInvalidNamespace   = Error("invalid namespace")
 	errInvalidPortFormat  = Error("invalid port format")
 )
 
@@ -69,13 +68,17 @@ func (h *Headscale) LoadACLPolicy(path string) error {
 	}
 
 	h.aclPolicy = &policy
+
+	return h.UpdateACLRules()
+}
+
+func (h *Headscale) UpdateACLRules() error {
 	rules, err := h.generateACLRules()
 	if err != nil {
 		return err
 	}
-	h.aclRules = rules
-
 	log.Trace().Interface("ACL", rules).Msg("ACL rules generated")
+	h.aclRules = rules
 
 	return nil
 }
@@ -83,16 +86,23 @@ func (h *Headscale) LoadACLPolicy(path string) error {
 func (h *Headscale) generateACLRules() ([]tailcfg.FilterRule, error) {
 	rules := []tailcfg.FilterRule{}
 
+	if h.aclPolicy == nil {
+		return nil, errEmptyPolicy
+	}
+
+	machines, err := h.ListAllMachines()
+	if err != nil {
+		return nil, err
+	}
+
 	for index, acl := range h.aclPolicy.ACLs {
 		if acl.Action != "accept" {
 			return nil, errInvalidAction
 		}
 
-		filterRule := tailcfg.FilterRule{}
-
 		srcIPs := []string{}
 		for innerIndex, user := range acl.Users {
-			srcs, err := h.generateACLPolicySrcIP(user)
+			srcs, err := h.generateACLPolicySrcIP(machines, *h.aclPolicy, user)
 			if err != nil {
 				log.Error().
 					Msgf("Error parsing ACL %d, User %d", index, innerIndex)
@@ -101,11 +111,10 @@ func (h *Headscale) generateACLRules() ([]tailcfg.FilterRule, error) {
 			}
 			srcIPs = append(srcIPs, srcs...)
 		}
-		filterRule.SrcIPs = srcIPs
 
 		destPorts := []tailcfg.NetPortRange{}
 		for innerIndex, ports := range acl.Ports {
-			dests, err := h.generateACLPolicyDestPorts(ports)
+			dests, err := h.generateACLPolicyDestPorts(machines, *h.aclPolicy, ports)
 			if err != nil {
 				log.Error().
 					Msgf("Error parsing ACL %d, Port %d", index, innerIndex)
@@ -124,11 +133,17 @@ func (h *Headscale) generateACLRules() ([]tailcfg.FilterRule, error) {
 	return rules, nil
 }
 
-func (h *Headscale) generateACLPolicySrcIP(u string) ([]string, error) {
+func (h *Headscale) generateACLPolicySrcIP(
-	return h.expandAlias(u)
+	machines []Machine,
+	aclPolicy ACLPolicy,
+	u string,
+) ([]string, error) {
+	return expandAlias(machines, aclPolicy, u)
 }
 
 func (h *Headscale) generateACLPolicyDestPorts(
+	machines []Machine,
+	aclPolicy ACLPolicy,
 	d string,
 ) ([]tailcfg.NetPortRange, error) {
 	tokens := strings.Split(d, ":")
@@ -149,11 +164,11 @@ func (h *Headscale) generateACLPolicyDestPorts(
 		alias = fmt.Sprintf("%s:%s", tokens[0], tokens[1])
 	}
 
-	expanded, err := h.expandAlias(alias)
+	expanded, err := expandAlias(machines, aclPolicy, alias)
 	if err != nil {
 		return nil, err
 	}
-	ports, err := h.expandPorts(tokens[len(tokens)-1])
+	ports, err := expandPorts(tokens[len(tokens)-1])
 	if err != nil {
 		return nil, err
 	}
@@ -172,21 +187,28 @@ func (h *Headscale) generateACLPolicyDestPorts(
 	return dests, nil
 }
 
-func (h *Headscale) expandAlias(alias string) ([]string, error) {
+// expandalias has an input of either
+// - a namespace
+// - a group
+// - a tag
+// and transform these in IPAddresses.
+func expandAlias(
+	machines []Machine,
+	aclPolicy ACLPolicy,
+	alias string,
+) ([]string, error) {
+	ips := []string{}
 	if alias == "*" {
 		return []string{"*"}, nil
 	}
 
 	if strings.HasPrefix(alias, "group:") {
-		if _, ok := h.aclPolicy.Groups[alias]; !ok {
+		namespaces, err := expandGroup(aclPolicy, alias)
-			return nil, errInvalidGroup
+		if err != nil {
+			return ips, err
 		}
-		ips := []string{}
+		for _, n := range namespaces {
-		for _, n := range h.aclPolicy.Groups[alias] {
+			nodes := filterMachinesByNamespace(machines, n)
-			nodes, err := h.ListMachinesInNamespace(n)
-			if err != nil {
-				return nil, errInvalidNamespace
-			}
 			for _, node := range nodes {
 				ips = append(ips, node.IPAddresses.ToStringSlice()...)
 			}
@@ -196,35 +218,23 @@ func (h *Headscale) expandAlias(alias string) ([]string, error) {
 	}
 
 	if strings.HasPrefix(alias, "tag:") {
-		if _, ok := h.aclPolicy.TagOwners[alias]; !ok {
+		owners, err := expandTagOwners(aclPolicy, alias)
-			return nil, errInvalidTag
+		if err != nil {
+			return ips, err
 		}
-
+		for _, namespace := range owners {
-		// This will have HORRIBLE performance.
+			machines := filterMachinesByNamespace(machines, namespace)
-		// We need to change the data model to better store tags
+			for _, machine := range machines {
-		machines := []Machine{}
+				if len(machine.HostInfo) == 0 {
-		if err := h.db.Where("registered").Find(&machines).Error; err != nil {
+					continue
-			return nil, err
-		}
-		ips := []string{}
-		for _, machine := range machines {
-			hostinfo := tailcfg.Hostinfo{}
-			if len(machine.HostInfo) != 0 {
-				hi, err := machine.HostInfo.MarshalJSON()
-				if err != nil {
-					return nil, err
 				}
-				err = json.Unmarshal(hi, &hostinfo)
+				hi, err := machine.GetHostInfo()
 				if err != nil {
-					return nil, err
+					return ips, err
 				}
-
+				for _, t := range hi.RequestTags {
-				// FIXME: Check TagOwners allows this
+					if alias == t {
-				for _, t := range hostinfo.RequestTags {
-					if alias[4:] == t {
 						ips = append(ips, machine.IPAddresses.ToStringSlice()...)
-
-						break
 					}
 				}
 			}
@@ -233,38 +243,82 @@ func (h *Headscale) expandAlias(alias string) ([]string, error) {
 		return ips, nil
 	}
 
-	n, err := h.GetNamespace(alias)
+	// if alias is a namespace
-	if err == nil {
+	nodes := filterMachinesByNamespace(machines, alias)
-		nodes, err := h.ListMachinesInNamespace(n.Name)
+	nodes, err := excludeCorrectlyTaggedNodes(aclPolicy, nodes, alias)
-		if err != nil {
+	if err != nil {
-			return nil, err
+		return ips, err
-		}
+	}
-		ips := []string{}
+	for _, n := range nodes {
-		for _, n := range nodes {
+		ips = append(ips, n.IPAddresses.ToStringSlice()...)
-			ips = append(ips, n.IPAddresses.ToStringSlice()...)
+	}
-		}
+	if len(ips) > 0 {
-
 		return ips, nil
 	}
 
-	if h, ok := h.aclPolicy.Hosts[alias]; ok {
+	// if alias is an host
+	if h, ok := aclPolicy.Hosts[alias]; ok {
 		return []string{h.String()}, nil
 	}
 
+	// if alias is an IP
 	ip, err := netaddr.ParseIP(alias)
 	if err == nil {
 		return []string{ip.String()}, nil
 	}
 
+	// if alias is an CIDR
 	cidr, err := netaddr.ParseIPPrefix(alias)
 	if err == nil {
 		return []string{cidr.String()}, nil
 	}
 
-	return nil, errInvalidUserSection
+	return ips, errInvalidUserSection
 }
 
-func (h *Headscale) expandPorts(portsStr string) (*[]tailcfg.PortRange, error) {
+// excludeCorrectlyTaggedNodes will remove from the list of input nodes the ones
+// that are correctly tagged since they should not be listed as being in the namespace
+// we assume in this function that we only have nodes from 1 namespace.
+func excludeCorrectlyTaggedNodes(
+	aclPolicy ACLPolicy,
+	nodes []Machine,
+	namespace string,
+) ([]Machine, error) {
+	out := []Machine{}
+	tags := []string{}
+	for tag, ns := range aclPolicy.TagOwners {
+		if containsString(ns, namespace) {
+			tags = append(tags, tag)
+		}
+	}
+	// for each machine if tag is in tags list, don't append it.
+	for _, machine := range nodes {
+		if len(machine.HostInfo) == 0 {
+			out = append(out, machine)
+
+			continue
+		}
+		hi, err := machine.GetHostInfo()
+		if err != nil {
+			return out, err
+		}
+		found := false
+		for _, t := range hi.RequestTags {
+			if containsString(tags, t) {
+				found = true
+
+				break
+			}
+		}
+		if !found {
+			out = append(out, machine)
+		}
+	}
+
+	return out, nil
+}
+
+func expandPorts(portsStr string) (*[]tailcfg.PortRange, error) {
 	if portsStr == "*" {
 		return &[]tailcfg.PortRange{
 			{First: portRangeBegin, Last: portRangeEnd},
@@ -306,3 +360,64 @@ func (h *Headscale) expandPorts(portsStr string) (*[]tailcfg.PortRange, error) {
 
 	return &ports, nil
 }
+
+func filterMachinesByNamespace(machines []Machine, namespace string) []Machine {
+	out := []Machine{}
+	for _, machine := range machines {
+		if machine.Namespace.Name == namespace {
+			out = append(out, machine)
+		}
+	}
+
+	return out
+}
+
+// expandTagOwners will return a list of namespace. An owner can be either a namespace or a group
+// a group cannot be composed of groups.
+func expandTagOwners(aclPolicy ACLPolicy, tag string) ([]string, error) {
+	var owners []string
+	ows, ok := aclPolicy.TagOwners[tag]
+	if !ok {
+		return []string{}, fmt.Errorf(
+			"%w. %v isn't owned by a TagOwner. Please add one first. https://tailscale.com/kb/1018/acls/#tag-owners",
+			errInvalidTag,
+			tag,
+		)
+	}
+	for _, owner := range ows {
+		if strings.HasPrefix(owner, "group:") {
+			gs, err := expandGroup(aclPolicy, owner)
+			if err != nil {
+				return []string{}, err
+			}
+			owners = append(owners, gs...)
+		} else {
+			owners = append(owners, owner)
+		}
+	}
+
+	return owners, nil
+}
+
+// expandGroup will return the list of namespace inside the group
+// after some validation.
+func expandGroup(aclPolicy ACLPolicy, group string) ([]string, error) {
+	groups, ok := aclPolicy.Groups[group]
+	if !ok {
+		return []string{}, fmt.Errorf(
+			"group %v isn't registered. %w",
+			group,
+			errInvalidGroup,
+		)
+	}
+	for _, g := range groups {
+		if strings.HasPrefix(g, "group:") {
+			return []string{}, fmt.Errorf(
+				"%w. A group cannot be composed of groups. https://tailscale.com/kb/1018/acls/#groups",
+				errInvalidGroup,
+			)
+		}
+	}
+
+	return groups, nil
+}

acls_test.go

@@ -1,7 +1,14 @@
 package headscale
 
 import (
+	"errors"
+	"reflect"
+	"testing"
+
 	"gopkg.in/check.v1"
+	"gorm.io/datatypes"
+	"inet.af/netaddr"
+	"tailscale.com/tailcfg"
 )
 
 func (s *Suite) TestWrongPath(c *check.C) {
@@ -52,6 +59,245 @@ func (s *Suite) TestBasicRule(c *check.C) {
 	c.Assert(rules, check.NotNil)
 }
 
+// TODO(kradalby): Make tests values safe, independent and descriptive.
+func (s *Suite) TestInvalidAction(c *check.C) {
+	app.aclPolicy = &ACLPolicy{
+		ACLs: []ACL{
+			{Action: "invalidAction", Users: []string{"*"}, Ports: []string{"*:*"}},
+		},
+	}
+	err := app.UpdateACLRules()
+	c.Assert(errors.Is(err, errInvalidAction), check.Equals, true)
+}
+
+func (s *Suite) TestInvalidGroupInGroup(c *check.C) {
+	// this ACL is wrong because the group in users sections doesn't exist
+	app.aclPolicy = &ACLPolicy{
+		Groups: Groups{
+			"group:test":  []string{"foo"},
+			"group:error": []string{"foo", "group:test"},
+		},
+		ACLs: []ACL{
+			{Action: "accept", Users: []string{"group:error"}, Ports: []string{"*:*"}},
+		},
+	}
+	err := app.UpdateACLRules()
+	c.Assert(errors.Is(err, errInvalidGroup), check.Equals, true)
+}
+
+func (s *Suite) TestInvalidTagOwners(c *check.C) {
+	// this ACL is wrong because no tagOwners own the requested tag for the server
+	app.aclPolicy = &ACLPolicy{
+		ACLs: []ACL{
+			{Action: "accept", Users: []string{"tag:foo"}, Ports: []string{"*:*"}},
+		},
+	}
+	err := app.UpdateACLRules()
+	c.Assert(errors.Is(err, errInvalidTag), check.Equals, true)
+}
+
+// this test should validate that we can expand a group in a TagOWner section and
+// match properly the IP's of the related hosts. The owner is valid and the tag is also valid.
+// the tag is matched in the Users section.
+func (s *Suite) TestValidExpandTagOwnersInUsers(c *check.C) {
+	namespace, err := app.CreateNamespace("user1")
+	c.Assert(err, check.IsNil)
+
+	pak, err := app.CreatePreAuthKey(namespace.Name, false, false, nil)
+	c.Assert(err, check.IsNil)
+
+	_, err = app.GetMachine("user1", "testmachine")
+	c.Assert(err, check.NotNil)
+	hostInfo := []byte(
+		"{\"OS\":\"centos\",\"Hostname\":\"testmachine\",\"RequestTags\":[\"tag:test\"]}",
+	)
+	machine := Machine{
+		ID:             0,
+		MachineKey:     "foo",
+		NodeKey:        "bar",
+		DiscoKey:       "faa",
+		Name:           "testmachine",
+		IPAddresses:    MachineAddresses{netaddr.MustParseIP("100.64.0.1")},
+		NamespaceID:    namespace.ID,
+		Registered:     true,
+		RegisterMethod: RegisterMethodAuthKey,
+		AuthKeyID:      uint(pak.ID),
+		HostInfo:       datatypes.JSON(hostInfo),
+	}
+	app.db.Save(&machine)
+
+	app.aclPolicy = &ACLPolicy{
+		Groups:    Groups{"group:test": []string{"user1", "user2"}},
+		TagOwners: TagOwners{"tag:test": []string{"user3", "group:test"}},
+		ACLs: []ACL{
+			{Action: "accept", Users: []string{"tag:test"}, Ports: []string{"*:*"}},
+		},
+	}
+	err = app.UpdateACLRules()
+	c.Assert(err, check.IsNil)
+	c.Assert(app.aclRules, check.HasLen, 1)
+	c.Assert(app.aclRules[0].SrcIPs, check.HasLen, 1)
+	c.Assert(app.aclRules[0].SrcIPs[0], check.Equals, "100.64.0.1")
+}
+
+// this test should validate that we can expand a group in a TagOWner section and
+// match properly the IP's of the related hosts. The owner is valid and the tag is also valid.
+// the tag is matched in the Ports section.
+func (s *Suite) TestValidExpandTagOwnersInPorts(c *check.C) {
+	namespace, err := app.CreateNamespace("user1")
+	c.Assert(err, check.IsNil)
+
+	pak, err := app.CreatePreAuthKey(namespace.Name, false, false, nil)
+	c.Assert(err, check.IsNil)
+
+	_, err = app.GetMachine("user1", "testmachine")
+	c.Assert(err, check.NotNil)
+	hostInfo := []byte(
+		"{\"OS\":\"centos\",\"Hostname\":\"testmachine\",\"RequestTags\":[\"tag:test\"]}",
+	)
+	machine := Machine{
+		ID:             1,
+		MachineKey:     "12345",
+		NodeKey:        "bar",
+		DiscoKey:       "faa",
+		Name:           "testmachine",
+		IPAddresses:    MachineAddresses{netaddr.MustParseIP("100.64.0.1")},
+		NamespaceID:    namespace.ID,
+		Registered:     true,
+		RegisterMethod: RegisterMethodAuthKey,
+		AuthKeyID:      uint(pak.ID),
+		HostInfo:       datatypes.JSON(hostInfo),
+	}
+	app.db.Save(&machine)
+
+	app.aclPolicy = &ACLPolicy{
+		Groups:    Groups{"group:test": []string{"user1", "user2"}},
+		TagOwners: TagOwners{"tag:test": []string{"user3", "group:test"}},
+		ACLs: []ACL{
+			{Action: "accept", Users: []string{"*"}, Ports: []string{"tag:test:*"}},
+		},
+	}
+	err = app.UpdateACLRules()
+	c.Assert(err, check.IsNil)
+	c.Assert(app.aclRules, check.HasLen, 1)
+	c.Assert(app.aclRules[0].DstPorts, check.HasLen, 1)
+	c.Assert(app.aclRules[0].DstPorts[0].IP, check.Equals, "100.64.0.1")
+}
+
+// need a test with:
+// tag on a host that isn't owned by a tag owners. So the namespace
+// of the host should be valid.
+func (s *Suite) TestInvalidTagValidNamespace(c *check.C) {
+	namespace, err := app.CreateNamespace("user1")
+	c.Assert(err, check.IsNil)
+
+	pak, err := app.CreatePreAuthKey(namespace.Name, false, false, nil)
+	c.Assert(err, check.IsNil)
+
+	_, err = app.GetMachine("user1", "testmachine")
+	c.Assert(err, check.NotNil)
+	hostInfo := []byte(
+		"{\"OS\":\"centos\",\"Hostname\":\"testmachine\",\"RequestTags\":[\"tag:foo\"]}",
+	)
+	machine := Machine{
+		ID:             1,
+		MachineKey:     "12345",
+		NodeKey:        "bar",
+		DiscoKey:       "faa",
+		Name:           "testmachine",
+		IPAddresses:    MachineAddresses{netaddr.MustParseIP("100.64.0.1")},
+		NamespaceID:    namespace.ID,
+		Registered:     true,
+		RegisterMethod: RegisterMethodAuthKey,
+		AuthKeyID:      uint(pak.ID),
+		HostInfo:       datatypes.JSON(hostInfo),
+	}
+	app.db.Save(&machine)
+
+	app.aclPolicy = &ACLPolicy{
+		TagOwners: TagOwners{"tag:test": []string{"user1"}},
+		ACLs: []ACL{
+			{Action: "accept", Users: []string{"user1"}, Ports: []string{"*:*"}},
+		},
+	}
+	err = app.UpdateACLRules()
+	c.Assert(err, check.IsNil)
+	c.Assert(app.aclRules, check.HasLen, 1)
+	c.Assert(app.aclRules[0].SrcIPs, check.HasLen, 1)
+	c.Assert(app.aclRules[0].SrcIPs[0], check.Equals, "100.64.0.1")
+}
+
+// tag on a host is owned by a tag owner, the tag is valid.
+// an ACL rule is matching the tag to a namespace. It should not be valid since the
+// host should be tied to the tag now.
+func (s *Suite) TestValidTagInvalidNamespace(c *check.C) {
+	namespace, err := app.CreateNamespace("user1")
+	c.Assert(err, check.IsNil)
+
+	pak, err := app.CreatePreAuthKey(namespace.Name, false, false, nil)
+	c.Assert(err, check.IsNil)
+
+	_, err = app.GetMachine("user1", "webserver")
+	c.Assert(err, check.NotNil)
+	hostInfo := []byte(
+		"{\"OS\":\"centos\",\"Hostname\":\"webserver\",\"RequestTags\":[\"tag:webapp\"]}",
+	)
+	machine := Machine{
+		ID:             1,
+		MachineKey:     "12345",
+		NodeKey:        "bar",
+		DiscoKey:       "faa",
+		Name:           "webserver",
+		IPAddresses:    MachineAddresses{netaddr.MustParseIP("100.64.0.1")},
+		NamespaceID:    namespace.ID,
+		Registered:     true,
+		RegisterMethod: RegisterMethodAuthKey,
+		AuthKeyID:      uint(pak.ID),
+		HostInfo:       datatypes.JSON(hostInfo),
+	}
+	app.db.Save(&machine)
+	_, err = app.GetMachine("user1", "user")
+	hostInfo = []byte("{\"OS\":\"debian\",\"Hostname\":\"user\"}")
+	c.Assert(err, check.NotNil)
+	machine = Machine{
+		ID:             2,
+		MachineKey:     "56789",
+		NodeKey:        "bar2",
+		DiscoKey:       "faab",
+		Name:           "user",
+		IPAddresses:    MachineAddresses{netaddr.MustParseIP("100.64.0.2")},
+		NamespaceID:    namespace.ID,
+		Registered:     true,
+		RegisterMethod: RegisterMethodAuthKey,
+		AuthKeyID:      uint(pak.ID),
+		HostInfo:       datatypes.JSON(hostInfo),
+	}
+	app.db.Save(&machine)
+
+	app.aclPolicy = &ACLPolicy{
+		TagOwners: TagOwners{"tag:webapp": []string{"user1"}},
+		ACLs: []ACL{
+			{
+				Action: "accept",
+				Users:  []string{"user1"},
+				Ports:  []string{"tag:webapp:80,443"},
+			},
+		},
+	}
+	err = app.UpdateACLRules()
+	c.Assert(err, check.IsNil)
+	c.Assert(app.aclRules, check.HasLen, 1)
+	c.Assert(app.aclRules[0].SrcIPs, check.HasLen, 1)
+	c.Assert(app.aclRules[0].SrcIPs[0], check.Equals, "100.64.0.2")
+	c.Assert(app.aclRules[0].DstPorts, check.HasLen, 2)
+	c.Assert(app.aclRules[0].DstPorts[0].Ports.First, check.Equals, uint16(80))
+	c.Assert(app.aclRules[0].DstPorts[0].Ports.Last, check.Equals, uint16(80))
+	c.Assert(app.aclRules[0].DstPorts[0].IP, check.Equals, "100.64.0.1")
+	c.Assert(app.aclRules[0].DstPorts[1].Ports.First, check.Equals, uint16(443))
+	c.Assert(app.aclRules[0].DstPorts[1].Ports.Last, check.Equals, uint16(443))
+	c.Assert(app.aclRules[0].DstPorts[1].IP, check.Equals, "100.64.0.1")
+}
+
 func (s *Suite) TestPortRange(c *check.C) {
 	err := app.LoadACLPolicy("./tests/acls/acl_policy_basic_range.hujson")
 	c.Assert(err, check.IsNil)
@@ -94,7 +340,7 @@ func (s *Suite) TestPortNamespace(c *check.C) {
 	ips, _ := app.getAvailableIPs()
 	machine := Machine{
 		ID:             0,
-		MachineKey:     "foo",
+		MachineKey:     "12345",
 		NodeKey:        "bar",
 		DiscoKey:       "faa",
 		Name:           "testmachine",
@@ -165,3 +411,723 @@ func (s *Suite) TestPortGroup(c *check.C) {
 	c.Assert(len(ips), check.Equals, 1)
 	c.Assert(rules[0].SrcIPs[0], check.Equals, ips[0].String())
 }
+
+func Test_expandGroup(t *testing.T) {
+	type args struct {
+		aclPolicy ACLPolicy
+		group     string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    []string
+		wantErr bool
+	}{
+		{
+			name: "simple test",
+			args: args{
+				aclPolicy: ACLPolicy{
+					Groups: Groups{
+						"group:test": []string{"user1", "user2", "user3"},
+						"group:foo":  []string{"user2", "user3"},
+					},
+				},
+				group: "group:test",
+			},
+			want:    []string{"user1", "user2", "user3"},
+			wantErr: false,
+		},
+		{
+			name: "InexistantGroup",
+			args: args{
+				aclPolicy: ACLPolicy{
+					Groups: Groups{
+						"group:test": []string{"user1", "user2", "user3"},
+						"group:foo":  []string{"user2", "user3"},
+					},
+				},
+				group: "group:undefined",
+			},
+			want:    []string{},
+			wantErr: true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := expandGroup(test.args.aclPolicy, test.args.group)
+			if (err != nil) != test.wantErr {
+				t.Errorf("expandGroup() error = %v, wantErr %v", err, test.wantErr)
+
+				return
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("expandGroup() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}
+
+func Test_expandTagOwners(t *testing.T) {
+	type args struct {
+		aclPolicy ACLPolicy
+		tag       string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    []string
+		wantErr bool
+	}{
+		{
+			name: "simple tag expansion",
+			args: args{
+				aclPolicy: ACLPolicy{
+					TagOwners: TagOwners{"tag:test": []string{"user1"}},
+				},
+				tag: "tag:test",
+			},
+			want:    []string{"user1"},
+			wantErr: false,
+		},
+		{
+			name: "expand with tag and group",
+			args: args{
+				aclPolicy: ACLPolicy{
+					Groups:    Groups{"group:foo": []string{"user1", "user2"}},
+					TagOwners: TagOwners{"tag:test": []string{"group:foo"}},
+				},
+				tag: "tag:test",
+			},
+			want:    []string{"user1", "user2"},
+			wantErr: false,
+		},
+		{
+			name: "expand with namespace and group",
+			args: args{
+				aclPolicy: ACLPolicy{
+					Groups:    Groups{"group:foo": []string{"user1", "user2"}},
+					TagOwners: TagOwners{"tag:test": []string{"group:foo", "user3"}},
+				},
+				tag: "tag:test",
+			},
+			want:    []string{"user1", "user2", "user3"},
+			wantErr: false,
+		},
+		{
+			name: "invalid tag",
+			args: args{
+				aclPolicy: ACLPolicy{
+					TagOwners: TagOwners{"tag:foo": []string{"group:foo", "user1"}},
+				},
+				tag: "tag:test",
+			},
+			want:    []string{},
+			wantErr: true,
+		},
+		{
+			name: "invalid group",
+			args: args{
+				aclPolicy: ACLPolicy{
+					Groups:    Groups{"group:bar": []string{"user1", "user2"}},
+					TagOwners: TagOwners{"tag:test": []string{"group:foo", "user2"}},
+				},
+				tag: "tag:test",
+			},
+			want:    []string{},
+			wantErr: true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := expandTagOwners(test.args.aclPolicy, test.args.tag)
+			if (err != nil) != test.wantErr {
+				t.Errorf("expandTagOwners() error = %v, wantErr %v", err, test.wantErr)
+
+				return
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("expandTagOwners() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}
+
+func Test_expandPorts(t *testing.T) {
+	type args struct {
+		portsStr string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    *[]tailcfg.PortRange
+		wantErr bool
+	}{
+		{
+			name: "wildcard",
+			args: args{portsStr: "*"},
+			want: &[]tailcfg.PortRange{
+				{First: portRangeBegin, Last: portRangeEnd},
+			},
+			wantErr: false,
+		},
+		{
+			name: "two ports",
+			args: args{portsStr: "80,443"},
+			want: &[]tailcfg.PortRange{
+				{First: 80, Last: 80},
+				{First: 443, Last: 443},
+			},
+			wantErr: false,
+		},
+		{
+			name: "a range and a port",
+			args: args{portsStr: "80-1024,443"},
+			want: &[]tailcfg.PortRange{
+				{First: 80, Last: 1024},
+				{First: 443, Last: 443},
+			},
+			wantErr: false,
+		},
+		{
+			name:    "out of bounds",
+			args:    args{portsStr: "854038"},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "wrong port",
+			args:    args{portsStr: "85a38"},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "wrong port in first",
+			args:    args{portsStr: "a-80"},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "wrong port in last",
+			args:    args{portsStr: "80-85a38"},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "wrong port format",
+			args:    args{portsStr: "80-85a38-3"},
+			want:    nil,
+			wantErr: true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := expandPorts(test.args.portsStr)
+			if (err != nil) != test.wantErr {
+				t.Errorf("expandPorts() error = %v, wantErr %v", err, test.wantErr)
+
+				return
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("expandPorts() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}
+
+func Test_listMachinesInNamespace(t *testing.T) {
+	type args struct {
+		machines  []Machine
+		namespace string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []Machine
+	}{
+		{
+			name: "1 machine in namespace",
+			args: args{
+				machines: []Machine{
+					{Namespace: Namespace{Name: "joe"}},
+				},
+				namespace: "joe",
+			},
+			want: []Machine{
+				{Namespace: Namespace{Name: "joe"}},
+			},
+		},
+		{
+			name: "3 machines, 2 in namespace",
+			args: args{
+				machines: []Machine{
+					{ID: 1, Namespace: Namespace{Name: "joe"}},
+					{ID: 2, Namespace: Namespace{Name: "marc"}},
+					{ID: 3, Namespace: Namespace{Name: "marc"}},
+				},
+				namespace: "marc",
+			},
+			want: []Machine{
+				{ID: 2, Namespace: Namespace{Name: "marc"}},
+				{ID: 3, Namespace: Namespace{Name: "marc"}},
+			},
+		},
+		{
+			name: "5 machines, 0 in namespace",
+			args: args{
+				machines: []Machine{
+					{ID: 1, Namespace: Namespace{Name: "joe"}},
+					{ID: 2, Namespace: Namespace{Name: "marc"}},
+					{ID: 3, Namespace: Namespace{Name: "marc"}},
+					{ID: 4, Namespace: Namespace{Name: "marc"}},
+					{ID: 5, Namespace: Namespace{Name: "marc"}},
+				},
+				namespace: "mickael",
+			},
+			want: []Machine{},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := filterMachinesByNamespace(test.args.machines, test.args.namespace); !reflect.DeepEqual(
+				got,
+				test.want,
+			) {
+				t.Errorf("listMachinesInNamespace() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}
+
+// nolint
+func Test_expandAlias(t *testing.T) {
+	type args struct {
+		machines  []Machine
+		aclPolicy ACLPolicy
+		alias     string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    []string
+		wantErr bool
+	}{
+		{
+			name: "wildcard",
+			args: args{
+				alias: "*",
+				machines: []Machine{
+					{IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.1")}},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.78.84.227"),
+						},
+					},
+				},
+				aclPolicy: ACLPolicy{},
+			},
+			want:    []string{"*"},
+			wantErr: false,
+		},
+		{
+			name: "simple group",
+			args: args{
+				alias: "group:accountant",
+				machines: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "mickael"},
+					},
+				},
+				aclPolicy: ACLPolicy{
+					Groups: Groups{"group:accountant": []string{"joe", "marc"}},
+				},
+			},
+			want:    []string{"100.64.0.1", "100.64.0.2", "100.64.0.3"},
+			wantErr: false,
+		},
+		{
+			name: "wrong group",
+			args: args{
+				alias: "group:hr",
+				machines: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "mickael"},
+					},
+				},
+				aclPolicy: ACLPolicy{
+					Groups: Groups{"group:accountant": []string{"joe", "marc"}},
+				},
+			},
+			want:    []string{},
+			wantErr: true,
+		},
+		{
+			name: "simple ipaddress",
+			args: args{
+				alias:     "10.0.0.3",
+				machines:  []Machine{},
+				aclPolicy: ACLPolicy{},
+			},
+			want:    []string{"10.0.0.3"},
+			wantErr: false,
+		},
+		{
+			name: "private network",
+			args: args{
+				alias:    "homeNetwork",
+				machines: []Machine{},
+				aclPolicy: ACLPolicy{
+					Hosts: Hosts{
+						"homeNetwork": netaddr.MustParseIPPrefix("192.168.1.0/24"),
+					},
+				},
+			},
+			want:    []string{"192.168.1.0/24"},
+			wantErr: false,
+		},
+		{
+			name: "simple host",
+			args: args{
+				alias:     "10.0.0.1",
+				machines:  []Machine{},
+				aclPolicy: ACLPolicy{},
+			},
+			want:    []string{"10.0.0.1"},
+			wantErr: false,
+		},
+		{
+			name: "simple CIDR",
+			args: args{
+				alias:     "10.0.0.0/16",
+				machines:  []Machine{},
+				aclPolicy: ACLPolicy{},
+			},
+			want:    []string{"10.0.0.0/16"},
+			wantErr: false,
+		},
+		{
+			name: "simple tag",
+			args: args{
+				alias: "tag:hr-webserver",
+				machines: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"foo\",\"RequestTags\":[\"tag:hr-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"foo\",\"RequestTags\":[\"tag:hr-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+				},
+				aclPolicy: ACLPolicy{
+					TagOwners: TagOwners{"tag:hr-webserver": []string{"joe"}},
+				},
+			},
+			want:    []string{"100.64.0.1", "100.64.0.2"},
+			wantErr: false,
+		},
+		{
+			name: "No tag defined",
+			args: args{
+				alias: "tag:hr-webserver",
+				machines: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "mickael"},
+					},
+				},
+				aclPolicy: ACLPolicy{
+					Groups: Groups{"group:accountant": []string{"joe", "marc"}},
+					TagOwners: TagOwners{
+						"tag:accountant-webserver": []string{"group:accountant"},
+					},
+				},
+			},
+			want:    []string{},
+			wantErr: true,
+		},
+		{
+			name: "list host in namespace without correctly tagged servers",
+			args: args{
+				alias: "joe",
+				machines: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"foo\",\"RequestTags\":[\"tag:accountant-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"foo\",\"RequestTags\":[\"tag:accountant-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+				},
+				aclPolicy: ACLPolicy{
+					TagOwners: TagOwners{"tag:accountant-webserver": []string{"joe"}},
+				},
+			},
+			want:    []string{"100.64.0.4"},
+			wantErr: false,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := expandAlias(
+				test.args.machines,
+				test.args.aclPolicy,
+				test.args.alias,
+			)
+			if (err != nil) != test.wantErr {
+				t.Errorf("expandAlias() error = %v, wantErr %v", err, test.wantErr)
+
+				return
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("expandAlias() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}
+
+func Test_excludeCorrectlyTaggedNodes(t *testing.T) {
+	type args struct {
+		aclPolicy ACLPolicy
+		nodes     []Machine
+		namespace string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    []Machine
+		wantErr bool
+	}{
+		{
+			name: "exclude nodes with valid tags",
+			args: args{
+				aclPolicy: ACLPolicy{
+					TagOwners: TagOwners{"tag:accountant-webserver": []string{"joe"}},
+				},
+				nodes: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"foo\",\"RequestTags\":[\"tag:accountant-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"foo\",\"RequestTags\":[\"tag:accountant-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+				},
+				namespace: "joe",
+			},
+			want: []Machine{
+				{
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.4")},
+					Namespace:   Namespace{Name: "joe"},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "all nodes have invalid tags, don't exclude them",
+			args: args{
+				aclPolicy: ACLPolicy{
+					TagOwners: TagOwners{"tag:accountant-webserver": []string{"joe"}},
+				},
+				nodes: []Machine{
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"hr-web1\",\"RequestTags\":[\"tag:hr-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "joe"},
+						HostInfo: []byte(
+							"{\"OS\":\"centos\",\"Hostname\":\"hr-web2\",\"RequestTags\":[\"tag:hr-webserver\"]}",
+						),
+					},
+					{
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.4"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+				},
+				namespace: "joe",
+			},
+			want: []Machine{
+				{
+					IPAddresses: MachineAddresses{
+						netaddr.MustParseIP("100.64.0.1"),
+					},
+					Namespace: Namespace{Name: "joe"},
+					HostInfo: []byte(
+						"{\"OS\":\"centos\",\"Hostname\":\"hr-web1\",\"RequestTags\":[\"tag:hr-webserver\"]}",
+					),
+				},
+				{
+					IPAddresses: MachineAddresses{
+						netaddr.MustParseIP("100.64.0.2"),
+					},
+					Namespace: Namespace{Name: "joe"},
+					HostInfo: []byte(
+						"{\"OS\":\"centos\",\"Hostname\":\"hr-web2\",\"RequestTags\":[\"tag:hr-webserver\"]}",
+					),
+				},
+				{
+					IPAddresses: MachineAddresses{
+						netaddr.MustParseIP("100.64.0.4"),
+					},
+					Namespace: Namespace{Name: "joe"},
+				},
+			},
+			wantErr: false,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, err := excludeCorrectlyTaggedNodes(
+				test.args.aclPolicy,
+				test.args.nodes,
+				test.args.namespace,
+			)
+			if (err != nil) != test.wantErr {
+				t.Errorf(
+					"excludeCorrectlyTaggedNodes() error = %v, wantErr %v",
+					err,
+					test.wantErr,
+				)
+
+				return
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("excludeCorrectlyTaggedNodes() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}

api.go

@@ -261,7 +261,16 @@ func (h *Headscale) getMapResponse(
 
 	var respBody []byte
 	if req.Compress == "zstd" {
-		src, _ := json.Marshal(resp)
+		src, err := json.Marshal(resp)
+		if err != nil {
+			log.Error().
+				Caller().
+				Str("func", "getMapResponse").
+				Err(err).
+				Msg("Failed to marshal response for the client")
+
+			return nil, err
+		}
 
 		encoder, _ := zstd.NewWriter(nil)
 		srcCompressed := encoder.EncodeAll(src, nil)
@@ -290,7 +299,16 @@ func (h *Headscale) getMapKeepAliveResponse(
 	var respBody []byte
 	var err error
 	if mapRequest.Compress == "zstd" {
-		src, _ := json.Marshal(mapResponse)
+		src, err := json.Marshal(mapResponse)
+		if err != nil {
+			log.Error().
+				Caller().
+				Str("func", "getMapKeepAliveResponse").
+				Err(err).
+				Msg("Failed to marshal keepalive response for the client")
+
+			return nil, err
+		}
 		encoder, _ := zstd.NewWriter(nil)
 		srcCompressed := encoder.EncodeAll(src, nil)
 		respBody = h.privateKey.SealTo(machineKey, srcCompressed)

dns.go

@@ -163,7 +163,15 @@ func getMapResponseDNSConfig(
 		dnsConfig = dnsConfigOrig.Clone()
 		dnsConfig.Domains = append(
 			dnsConfig.Domains,
-			fmt.Sprintf("%s.%s", machine.Namespace.Name, baseDomain),
+			fmt.Sprintf(
+				"%s.%s",
+				strings.ReplaceAll(
+					machine.Namespace.Name,
+					"@",
+					".",
+				), // Replace @ with . for valid domain for machine
+				baseDomain,
+			),
 		)
 
 		namespaceSet := set.New(set.ThreadSafe)
@@ -171,8 +179,14 @@ func getMapResponseDNSConfig(
 		for _, p := range peers {
 			namespaceSet.Add(p.Namespace)
 		}
-		for _, namespace := range namespaceSet.List() {
+		for _, ns := range namespaceSet.List() {
-			dnsRoute := fmt.Sprintf("%s.%s", namespace.(Namespace).Name, baseDomain)
+			namespace, ok := ns.(Namespace)
+			if !ok {
+				dnsConfig = dnsConfigOrig
+
+				continue
+			}
+			dnsRoute := fmt.Sprintf("%v.%v", namespace.Name, baseDomain)
 			dnsConfig.Routes[dnsRoute] = nil
 		}
 	} else {

docs/README.md

@@ -39,6 +39,14 @@ use namespaces (which are the equivalent to user/logins in Tailscale.com).
 
 Please check https://tailscale.com/kb/1018/acls/, and `./tests/acls/` in this repo for working examples.
 
+When using ACL's the Namespace borders are no longer applied. All machines
+whichever the Namespace have the ability to communicate with other hosts as
+long as the ACL's permits this exchange.
+
+The [ACLs](acls.md) document should help understand a fictional case of setting
+up ACLs in a small company. All concepts presented in this document could be
+applied outside of business oriented usage.
+
 ### Apple devices
 
 An endpoint with information on how to connect your Apple devices (currently macOS only) is available at `/apple` on your running instance.

docs/acls.md

@@ -0,0 +1,141 @@
+# ACLs use case example
+
+Let's build an example use case for a small business (It may be the place where
+ACL's are the most useful).
+
+We have a small company with a boss, an admin, two developers and an intern.
+
+The boss should have access to all servers but not to the users hosts. Admin
+should also have access to all hosts except that their permissions should be
+limited to maintaining the hosts (for example purposes). The developers can do
+anything they want on dev hosts, but only watch on productions hosts. Intern
+can only interact with the development servers.
+
+Each user have at least a device connected to the network and we have some
+servers.
+
+- database.prod
+- database.dev
+- app-server1.prod
+- app-server1.dev
+- billing.internal
+
+## Setup of the network
+
+Let's create the namespaces. Each user should have his own namespace. The users
+here are represented as namespaces.
+
+```bash
+headscale namespaces create boss
+headscale namespaces create admin1
+headscale namespaces create dev1
+headscale namespaces create dev2
+headscale namespaces create intern1
+```
+
+We don't need to create namespaces for the servers because the servers will be
+tagged. When registering the servers we will need to add the flag
+`--advertised-tags=tag:<tag1>,tag:<tag2>`, and the user (namespace) that is
+registering the server should be allowed to do it. Since anyone can add tags to
+a server they can register, the check of the tags is done on headscale server
+and only valid tags are applied. A tag is valid if the namespace that is
+registering it is allowed to do it.
+
+Here are the ACL's to implement the same permissions as above:
+
+```json
+{
+  // groups are collections of users having a common scope. A user can be in multiple groups
+  // groups cannot be composed of groups
+  "groups": {
+    "group:boss": ["boss"],
+    "group:dev": ["dev1", "dev2"],
+    "group:admin": ["admin1"],
+    "group:intern": ["intern1"]
+  },
+  // tagOwners in tailscale is an association between a TAG and the people allowed to set this TAG on a server.
+  // This is documented [here](https://tailscale.com/kb/1068/acl-tags#defining-a-tag)
+  // and explained [here](https://tailscale.com/blog/rbac-like-it-was-meant-to-be/)
+  "tagOwners": {
+    // the administrators can add servers in production
+    "tag:prod-databases": ["group:admin"],
+    "tag:prod-app-servers": ["group:admin"],
+
+    // the boss can tag any server as internal
+    "tag:internal": ["group:boss"],
+
+    // dev can add servers for dev purposes as well as admins
+    "tag:dev-databases": ["group:admin", "group:dev"],
+    "tag:dev-app-servers": ["group:admin", "group:dev"]
+
+    // interns cannot add servers
+  },
+  "acls": [
+    // boss have access to all servers
+    {
+      "action": "accept",
+      "users": ["group:boss"],
+      "ports": [
+        "tag:prod-databases:*",
+        "tag:prod-app-servers:*",
+        "tag:internal:*",
+        "tag:dev-databases:*",
+        "tag:dev-app-servers:*"
+      ]
+    },
+
+    // admin have only access to administrative ports of the servers
+    {
+      "action": "accept",
+      "users": ["group:admin"],
+      "ports": [
+        "tag:prod-databases:22",
+        "tag:prod-app-servers:22",
+        "tag:internal:22",
+        "tag:dev-databases:22",
+        "tag:dev-app-servers:22"
+      ]
+    },
+
+    // developers have access to databases servers and application servers on all ports
+    // they can only view the applications servers in prod and have no access to databases servers in production
+    {
+      "action": "accept",
+      "users": ["group:dev"],
+      "ports": [
+        "tag:dev-databases:*",
+        "tag:dev-app-servers:*",
+        "tag:prod-app-servers:80,443"
+      ]
+    },
+
+    // servers should be able to talk to database. Database should not be able to initiate connections to
+    // applications servers
+    {
+      "action": "accept",
+      "users": ["tag:dev-app-servers"],
+      "ports": ["tag:dev-databases:5432"]
+    },
+    {
+      "action": "accept",
+      "users": ["tag:prod-app-servers"],
+      "ports": ["tag:prod-databases:5432"]
+    },
+
+    // interns have access to dev-app-servers only in reading mode
+    {
+      "action": "accept",
+      "users": ["group:intern"],
+      "ports": ["tag:dev-app-servers:80,443"]
+    },
+
+    // We still have to allow internal namespaces communications since nothing guarantees that each user have
+    // their own namespaces.
+    { "action": "accept", "users": ["boss"], "ports": ["boss:*"] },
+    { "action": "accept", "users": ["dev1"], "ports": ["dev1:*"] },
+    { "action": "accept", "users": ["dev2"], "ports": ["dev2:*"] },
+    { "action": "accept", "users": ["admin1"], "ports": ["admin1:*"] },
+    { "action": "accept", "users": ["intern1"], "ports": ["intern1:*"] }
+  ]
+}
+```

machine.go

@@ -119,6 +119,118 @@ func (machine Machine) isExpired() bool {
 	return time.Now().UTC().After(*machine.Expiry)
 }
 
+func (h *Headscale) ListAllMachines() ([]Machine, error) {
+	machines := []Machine{}
+	if err := h.db.Preload("AuthKey").
+		Preload("AuthKey.Namespace").
+		Preload("Namespace").
+		Where("registered").
+		Find(&machines).Error; err != nil {
+		return nil, err
+	}
+
+	return machines, nil
+}
+
+func containsAddresses(inputs []string, addrs []string) bool {
+	for _, addr := range addrs {
+		if containsString(inputs, addr) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// matchSourceAndDestinationWithRule.
+func matchSourceAndDestinationWithRule(
+	ruleSources []string,
+	ruleDestinations []string,
+	source []string,
+	destination []string,
+) bool {
+	return containsAddresses(ruleSources, source) &&
+		containsAddresses(ruleDestinations, destination)
+}
+
+// getFilteredByACLPeerss should return the list of peers authorized to be accessed from machine.
+func getFilteredByACLPeers(
+	machines []Machine,
+	rules []tailcfg.FilterRule,
+	machine *Machine,
+) Machines {
+	log.Trace().
+		Caller().
+		Str("machine", machine.Name).
+		Msg("Finding peers filtered by ACLs")
+
+	peers := make(map[uint64]Machine)
+	// Aclfilter peers here. We are itering through machines in all namespaces and search through the computed aclRules
+	// for match between rule SrcIPs and DstPorts. If the rule is a match we allow the machine to be viewable.
+
+	// FIXME: On official control plane if a rule allow user A to talk to user B but NO rule allows user B to talk to
+	// user A. The behaviour is the following
+	//
+	// On official tailscale control plane:
+	//   on first `tailscale status`` on node A we can see node B. The `tailscale status` command on node B doesn't show node A
+	//   We can successfully establish a communication from A to B. When it's done, if we run the `tailscale status` command
+	//   on node B again we can now see node A. It's not possible to establish a communication from node B to node A.
+	// On this implementation of the feature
+	//   on any `tailscale status` command on node A we can see node B. The `tailscale status` command on node B DOES show A.
+	//
+	// I couldn't find a way to not clutter the output of `tailscale status` with all nodes that we could be talking to.
+	// In order to do this we would need to be able to identify that node A want to talk to node B but that Node B doesn't know
+	// how to talk to node A and then add the peering resource.
+
+	for _, peer := range machines {
+		if peer.ID == machine.ID {
+			continue
+		}
+		for _, rule := range rules {
+			var dst []string
+			for _, d := range rule.DstPorts {
+				dst = append(dst, d.IP)
+			}
+			if matchSourceAndDestinationWithRule(
+				rule.SrcIPs,
+				dst,
+				machine.IPAddresses.ToStringSlice(),
+				peer.IPAddresses.ToStringSlice(),
+			) || // match source and destination
+				matchSourceAndDestinationWithRule(
+					rule.SrcIPs,
+					dst,
+					machine.IPAddresses.ToStringSlice(),
+					[]string{"*"},
+				) || // match source and all destination
+				matchSourceAndDestinationWithRule(
+					rule.SrcIPs,
+					dst,
+					peer.IPAddresses.ToStringSlice(),
+					machine.IPAddresses.ToStringSlice(),
+				) { // match return path
+				peers[peer.ID] = peer
+			}
+		}
+	}
+
+	authorizedPeers := make([]Machine, 0, len(peers))
+	for _, m := range peers {
+		authorizedPeers = append(authorizedPeers, m)
+	}
+	sort.Slice(
+		authorizedPeers,
+		func(i, j int) bool { return authorizedPeers[i].ID < authorizedPeers[j].ID },
+	)
+
+	log.Trace().
+		Caller().
+		Str("machine", machine.Name).
+		Msgf("Found some machines: %v", machines)
+
+	return authorizedPeers
+}
+
 func (h *Headscale) getDirectPeers(machine *Machine) (Machines, error) {
 	log.Trace().
 		Caller().
@@ -206,39 +318,54 @@ func (h *Headscale) getSharedTo(machine *Machine) (Machines, error) {
 }
 
 func (h *Headscale) getPeers(machine *Machine) (Machines, error) {
-	direct, err := h.getDirectPeers(machine)
+	var peers Machines
-	if err != nil {
+	var err error
-		log.Error().
-			Caller().
-			Err(err).
-			Msg("Cannot fetch peers")
 
-		return Machines{}, err
+	// If ACLs rules are defined, filter visible host list with the ACLs
+	// else use the classic namespace scope
+	if h.aclPolicy != nil {
+		var machines []Machine
+		machines, err = h.ListAllMachines()
+		if err != nil {
+			log.Error().Err(err).Msg("Error retrieving list of machines")
+
+			return Machines{}, err
+		}
+		peers = getFilteredByACLPeers(machines, h.aclRules, machine)
+	} else {
+		direct, err := h.getDirectPeers(machine)
+		if err != nil {
+			log.Error().
+				Caller().
+				Err(err).
+				Msg("Cannot fetch peers")
+
+			return Machines{}, err
+		}
+
+		shared, err := h.getShared(machine)
+		if err != nil {
+			log.Error().
+				Caller().
+				Err(err).
+				Msg("Cannot fetch peers")
+
+			return Machines{}, err
+		}
+
+		sharedTo, err := h.getSharedTo(machine)
+		if err != nil {
+			log.Error().
+				Caller().
+				Err(err).
+				Msg("Cannot fetch peers")
+
+			return Machines{}, err
+		}
+		peers = append(direct, shared...)
+		peers = append(peers, sharedTo...)
 	}
 
-	shared, err := h.getShared(machine)
-	if err != nil {
-		log.Error().
-			Caller().
-			Err(err).
-			Msg("Cannot fetch peers")
-
-		return Machines{}, err
-	}
-
-	sharedTo, err := h.getSharedTo(machine)
-	if err != nil {
-		log.Error().
-			Caller().
-			Err(err).
-			Msg("Cannot fetch peers")
-
-		return Machines{}, err
-	}
-
-	peers := append(direct, shared...)
-	peers = append(peers, sharedTo...)
-
 	sort.Slice(peers, func(i, j int) bool { return peers[i].ID < peers[j].ID })
 
 	log.Trace().
@@ -597,7 +724,11 @@ func (machine Machine) toNode(
 		hostname = fmt.Sprintf(
 			"%s.%s.%s",
 			machine.Name,
-			machine.Namespace.Name,
+			strings.ReplaceAll(
+				machine.Namespace.Name,
+				"@",
+				".",
+			), // Replace @ with . for valid domain for machine
 			baseDomain,
 		)
 	} else {

machine_test.go

@@ -1,11 +1,15 @@
 package headscale
 
 import (
+	"fmt"
+	"reflect"
 	"strconv"
+	"testing"
 	"time"
 
 	"gopkg.in/check.v1"
 	"inet.af/netaddr"
+	"tailscale.com/tailcfg"
 )
 
 func (s *Suite) TestGetMachine(c *check.C) {
@@ -154,6 +158,89 @@ func (s *Suite) TestGetDirectPeers(c *check.C) {
 	c.Assert(peersOfMachine0[8].Name, check.Equals, "testmachine10")
 }
 
+func (s *Suite) TestGetACLFilteredPeers(c *check.C) {
+	type base struct {
+		namespace *Namespace
+		key       *PreAuthKey
+	}
+
+	stor := make([]base, 0)
+
+	for _, name := range []string{"test", "admin"} {
+		namespace, err := app.CreateNamespace(name)
+		c.Assert(err, check.IsNil)
+		pak, err := app.CreatePreAuthKey(namespace.Name, false, false, nil)
+		c.Assert(err, check.IsNil)
+		stor = append(stor, base{namespace, pak})
+	}
+
+	_, err := app.GetMachineByID(0)
+	c.Assert(err, check.NotNil)
+
+	for index := 0; index <= 10; index++ {
+		machine := Machine{
+			ID:         uint64(index),
+			MachineKey: "foo" + strconv.Itoa(index),
+			NodeKey:    "bar" + strconv.Itoa(index),
+			DiscoKey:   "faa" + strconv.Itoa(index),
+			IPAddresses: MachineAddresses{
+				netaddr.MustParseIP(fmt.Sprintf("100.64.0.%v", strconv.Itoa(index+1))),
+			},
+			Name:           "testmachine" + strconv.Itoa(index),
+			NamespaceID:    stor[index%2].namespace.ID,
+			Registered:     true,
+			RegisterMethod: RegisterMethodAuthKey,
+			AuthKeyID:      uint(stor[index%2].key.ID),
+		}
+		app.db.Save(&machine)
+	}
+
+	app.aclPolicy = &ACLPolicy{
+		Groups: map[string][]string{
+			"group:test": {"admin"},
+		},
+		Hosts:     map[string]netaddr.IPPrefix{},
+		TagOwners: map[string][]string{},
+		ACLs: []ACL{
+			{Action: "accept", Users: []string{"admin"}, Ports: []string{"*:*"}},
+			{Action: "accept", Users: []string{"test"}, Ports: []string{"test:*"}},
+		},
+		Tests: []ACLTest{},
+	}
+
+	err = app.UpdateACLRules()
+	c.Assert(err, check.IsNil)
+
+	adminMachine, err := app.GetMachineByID(1)
+	c.Logf("Machine(%v), namespace: %v", adminMachine.Name, adminMachine.Namespace)
+	c.Assert(err, check.IsNil)
+
+	testMachine, err := app.GetMachineByID(2)
+	c.Logf("Machine(%v), namespace: %v", testMachine.Name, testMachine.Namespace)
+	c.Assert(err, check.IsNil)
+
+	_, err = testMachine.GetHostInfo()
+	c.Assert(err, check.IsNil)
+
+	machines, err := app.ListAllMachines()
+	c.Assert(err, check.IsNil)
+
+	peersOfTestMachine := getFilteredByACLPeers(machines, app.aclRules, testMachine)
+	peersOfAdminMachine := getFilteredByACLPeers(machines, app.aclRules, adminMachine)
+
+	c.Log(peersOfTestMachine)
+	c.Assert(len(peersOfTestMachine), check.Equals, 4)
+	c.Assert(peersOfTestMachine[0].Name, check.Equals, "testmachine4")
+	c.Assert(peersOfTestMachine[1].Name, check.Equals, "testmachine6")
+	c.Assert(peersOfTestMachine[3].Name, check.Equals, "testmachine10")
+
+	c.Log(peersOfAdminMachine)
+	c.Assert(len(peersOfAdminMachine), check.Equals, 9)
+	c.Assert(peersOfAdminMachine[0].Name, check.Equals, "testmachine2")
+	c.Assert(peersOfAdminMachine[2].Name, check.Equals, "testmachine4")
+	c.Assert(peersOfAdminMachine[5].Name, check.Equals, "testmachine7")
+}
+
 func (s *Suite) TestExpireMachine(c *check.C) {
 	namespace, err := app.CreateNamespace("test")
 	c.Assert(err, check.IsNil)
@@ -208,3 +295,178 @@ func (s *Suite) TestSerdeAddressStrignSlice(c *check.C) {
 		c.Assert(deserialized[i], check.Equals, input[i])
 	}
 }
+
+func Test_getFilteredByACLPeers(t *testing.T) {
+	type args struct {
+		machines []Machine
+		rules    []tailcfg.FilterRule
+		machine  *Machine
+	}
+	tests := []struct {
+		name string
+		args args
+		want Machines
+	}{
+		{
+			name: "all hosts can talk to each other",
+			args: args{
+				machines: []Machine{ // list of all machines in the database
+					{
+						ID: 1,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						ID: 2,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						ID: 3,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "mickael"},
+					},
+				},
+				rules: []tailcfg.FilterRule{ // list of all ACLRules registered
+					{
+						SrcIPs: []string{"100.64.0.1", "100.64.0.2", "100.64.0.3"},
+						DstPorts: []tailcfg.NetPortRange{
+							{IP: "*"},
+						},
+					},
+				},
+				machine: &Machine{ // current machine
+					ID:          1,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.1")},
+					Namespace:   Namespace{Name: "joe"},
+				},
+			},
+			want: Machines{
+				{
+					ID:          2,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.2")},
+					Namespace:   Namespace{Name: "marc"},
+				},
+				{
+					ID:          3,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.3")},
+					Namespace:   Namespace{Name: "mickael"},
+				},
+			},
+		},
+		{
+			name: "One host can talk to another, but not all hosts",
+			args: args{
+				machines: []Machine{ // list of all machines in the database
+					{
+						ID: 1,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						ID: 2,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						ID: 3,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "mickael"},
+					},
+				},
+				rules: []tailcfg.FilterRule{ // list of all ACLRules registered
+					{
+						SrcIPs: []string{"100.64.0.1", "100.64.0.2", "100.64.0.3"},
+						DstPorts: []tailcfg.NetPortRange{
+							{IP: "100.64.0.2"},
+						},
+					},
+				},
+				machine: &Machine{ // current machine
+					ID:          1,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.1")},
+					Namespace:   Namespace{Name: "joe"},
+				},
+			},
+			want: Machines{
+				{
+					ID:          2,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.2")},
+					Namespace:   Namespace{Name: "marc"},
+				},
+			},
+		},
+		{
+			name: "host cannot directly talk to destination, but return path is authorized",
+			args: args{
+				machines: []Machine{ // list of all machines in the database
+					{
+						ID: 1,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.1"),
+						},
+						Namespace: Namespace{Name: "joe"},
+					},
+					{
+						ID: 2,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.2"),
+						},
+						Namespace: Namespace{Name: "marc"},
+					},
+					{
+						ID: 3,
+						IPAddresses: MachineAddresses{
+							netaddr.MustParseIP("100.64.0.3"),
+						},
+						Namespace: Namespace{Name: "mickael"},
+					},
+				},
+				rules: []tailcfg.FilterRule{ // list of all ACLRules registered
+					{
+						SrcIPs: []string{"100.64.0.3"},
+						DstPorts: []tailcfg.NetPortRange{
+							{IP: "100.64.0.2"},
+						},
+					},
+				},
+				machine: &Machine{ // current machine
+					ID:          1,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.2")},
+					Namespace:   Namespace{Name: "marc"},
+				},
+			},
+			want: Machines{
+				{
+					ID:          3,
+					IPAddresses: MachineAddresses{netaddr.MustParseIP("100.64.0.3")},
+					Namespace:   Namespace{Name: "mickael"},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := getFilteredByACLPeers(
+				tt.args.machines,
+				tt.args.rules,
+				tt.args.machine,
+			)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("getFilteredByACLPeers() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

poll.go

@@ -85,12 +85,26 @@ func (h *Headscale) PollNetMapHandler(ctx *gin.Context) {
 		Str("machine", machine.Name).
 		Msg("Found machine in database")
 
-	hostinfo, _ := json.Marshal(req.Hostinfo)
+	hostinfo, err := json.Marshal(req.Hostinfo)
+	if err != nil {
+		return
+	}
 	machine.Name = req.Hostinfo.Hostname
 	machine.HostInfo = datatypes.JSON(hostinfo)
 	machine.DiscoKey = DiscoPublicKeyStripPrefix(req.DiscoKey)
 	now := time.Now().UTC()
 
+	// update ACLRules with peer informations (to update server tags if necessary)
+	if h.aclPolicy != nil {
+		err = h.UpdateACLRules()
+		if err != nil {
+			log.Error().
+				Caller().
+				Str("func", "handleAuthKey").
+				Str("machine", machine.Name).
+				Err(err)
+		}
+	}
 	// From Tailscale client:
 	//
 	// ReadOnly is whether the client just wants to fetch the MapResponse,
@@ -100,7 +114,17 @@ func (h *Headscale) PollNetMapHandler(ctx *gin.Context) {
 	// The intended use is for clients to discover the DERP map at start-up
 	// before their first real endpoint update.
 	if !req.ReadOnly {
-		endpoints, _ := json.Marshal(req.Endpoints)
+		endpoints, err := json.Marshal(req.Endpoints)
+		if err != nil {
+			log.Error().
+				Caller().
+				Str("func", "PollNetMapHandler").
+				Err(err).
+				Msg("Failed to mashal requested endpoints for the client")
+			ctx.String(http.StatusInternalServerError, ":(")
+
+			return
+		}
 		machine.Endpoints = datatypes.JSON(endpoints)
 		machine.LastSeen = &now
 	}

utils.go

@@ -212,6 +212,16 @@ func (h *Headscale) getUsedIPs() ([]netaddr.IP, error) {
 	return ips, nil
 }
 
+func containsString(ss []string, s string) bool {
+	for _, v := range ss {
+		if v == s {
+			return true
+		}
+	}
+
+	return false
+}
+
 func containsIPs(ips []netaddr.IP, ip netaddr.IP) bool {
 	for _, v := range ips {
 		if v == ip {