app service unix socket support (#3022)

This is the last part of unix socket support to talk to app servers, go
based app services already support unix sockets:

https://github.com/mautrix/go/commit/5a68173fe39345b8473e04bfa67cae5a13f6ca7f
```
appservice:
  # The address that the homeserver can use to connect to this appservice.
  address: unix:///var/snap/matrix/current/whatsapp.socket

  # The hostname and port where this appservice should listen.
  hostname: /var/snap/matrix/current/whatsapp.socket
  port: 0
```

### Pull Request Checklist

<!-- Please read
https://matrix-org.github.io/dendrite/development/contributing before
submitting your pull request -->

* [x] I have added Go unit tests or [Complement integration
tests](https://github.com/matrix-org/complement) for this PR _or_ I have
justified why this PR doesn't need tests
* [x] Pull request includes a [sign off below using a legally
identifiable
name](https://matrix-org.github.io/dendrite/development/contributing#sign-off)
_or_ I have already signed off privately

Signed-off-by: `Boris Rybalkin <ribalkin@gmail.com>`

6 files changed, 189 insertions, 61 deletions

diff --git a/.gitignore b/.gitignore
index fe5e8279..dcfbf800 100644
--- a/.gitignore
+++ b/.gitignore
@@ -74,3 +74,4 @@ complement/
 docs/_site
 
 media_store/
+build
\ No newline at end of file
diff --git a/appservice/appservice.go b/appservice/appservice.go
index d13d9eb1..1f6037ee 100644
--- a/appservice/appservice.go
+++ b/appservice/appservice.go
@@ -16,10 +16,7 @@ package appservice
 
 import (
 	"context"
-	"crypto/tls"
-	"net/http"
 	"sync"
-	"time"
 
 	"github.com/matrix-org/dendrite/setup/jetstream"
 	"github.com/matrix-org/dendrite/setup/process"
@@ -44,20 +41,10 @@ func NewInternalAPI(
 	userAPI userapi.AppserviceUserAPI,
 	rsAPI roomserverAPI.RoomserverInternalAPI,
 ) appserviceAPI.AppServiceInternalAPI {
-	client := &http.Client{
-		Timeout: time.Second * 30,
-		Transport: &http.Transport{
-			DisableKeepAlives: true,
-			TLSClientConfig: &tls.Config{
-				InsecureSkipVerify: cfg.AppServiceAPI.DisableTLSValidation,
-			},
-			Proxy: http.ProxyFromEnvironment,
-		},
-	}
+
 	// Create appserivce query API with an HTTP client that will be used for all
 	// outbound and inbound requests (inbound only for the internal API)
 	appserviceQueryAPI := &query.AppServiceQueryAPI{
-		HTTPClient:    client,
 		Cfg:           &cfg.AppServiceAPI,
 		ProtocolCache: map[string]appserviceAPI.ASProtocolResponse{},
 		CacheMu:       sync.Mutex{},
@@ -84,7 +71,7 @@ func NewInternalAPI(
 	js, _ := natsInstance.Prepare(processContext, &cfg.Global.JetStream)
 	consumer := consumers.NewOutputRoomEventConsumer(
 		processContext, &cfg.AppServiceAPI,
-		client, js, rsAPI,
+		js, rsAPI,
 	)
 	if err := consumer.Start(); err != nil {
 		logrus.WithError(err).Panicf("failed to start appservice roomserver consumer")
diff --git a/appservice/appservice_test.go b/appservice/appservice_test.go
index 752901a9..5189bdf9 100644
--- a/appservice/appservice_test.go
+++ b/appservice/appservice_test.go
@@ -3,14 +3,19 @@ package appservice_test
 import (
 	"context"
 	"encoding/json"
+	"fmt"
+	"net"
 	"net/http"
 	"net/http/httptest"
+	"path"
 	"reflect"
 	"regexp"
 	"strings"
 	"testing"
 	"time"
 
+	"github.com/stretchr/testify/assert"
+
 	"github.com/matrix-org/dendrite/appservice"
 	"github.com/matrix-org/dendrite/appservice/api"
 	"github.com/matrix-org/dendrite/internal/caching"
@@ -114,20 +119,20 @@ func TestAppserviceInternalAPI(t *testing.T) {
 		defer close()
 
 		// Create a dummy application service
-		cfg.AppServiceAPI.Derived.ApplicationServices = []config.ApplicationService{
-			{
-				ID:              "someID",
-				URL:             srv.URL,
-				ASToken:         "",
-				HSToken:         "",
-				SenderLocalpart: "senderLocalPart",
-				NamespaceMap: map[string][]config.ApplicationServiceNamespace{
-					"users":   {{RegexpObject: regexp.MustCompile("as-.*")}},
-					"aliases": {{RegexpObject: regexp.MustCompile("asroom-.*")}},
-				},
-				Protocols: []string{existingProtocol},
+		as := &config.ApplicationService{
+			ID:              "someID",
+			URL:             srv.URL,
+			ASToken:         "",
+			HSToken:         "",
+			SenderLocalpart: "senderLocalPart",
+			NamespaceMap: map[string][]config.ApplicationServiceNamespace{
+				"users":   {{RegexpObject: regexp.MustCompile("as-.*")}},
+				"aliases": {{RegexpObject: regexp.MustCompile("asroom-.*")}},
 			},
+			Protocols: []string{existingProtocol},
 		}
+		as.CreateHTTPClient(cfg.AppServiceAPI.DisableTLSValidation)
+		cfg.AppServiceAPI.Derived.ApplicationServices = []config.ApplicationService{*as}
 
 		t.Cleanup(func() {
 			ctx.ShutdownDendrite()
@@ -145,6 +150,103 @@ func TestAppserviceInternalAPI(t *testing.T) {
 	})
 }
 
+func TestAppserviceInternalAPI_UnixSocket_Simple(t *testing.T) {
+
+	// Set expected results
+	existingProtocol := "irc"
+	wantLocationResponse := []api.ASLocationResponse{{Protocol: existingProtocol, Fields: []byte("{}")}}
+	wantUserResponse := []api.ASUserResponse{{Protocol: existingProtocol, Fields: []byte("{}")}}
+	wantProtocolResponse := api.ASProtocolResponse{Instances: []api.ProtocolInstance{{Fields: []byte("{}")}}}
+
+	// create a dummy AS url, handling some cases
+	srv := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case strings.Contains(r.URL.Path, "location"):
+			// Check if we've got an existing protocol, if so, return a proper response.
+			if r.URL.Path[len(r.URL.Path)-len(existingProtocol):] == existingProtocol {
+				if err := json.NewEncoder(w).Encode(wantLocationResponse); err != nil {
+					t.Fatalf("failed to encode response: %s", err)
+				}
+				return
+			}
+			if err := json.NewEncoder(w).Encode([]api.ASLocationResponse{}); err != nil {
+				t.Fatalf("failed to encode response: %s", err)
+			}
+			return
+		case strings.Contains(r.URL.Path, "user"):
+			if r.URL.Path[len(r.URL.Path)-len(existingProtocol):] == existingProtocol {
+				if err := json.NewEncoder(w).Encode(wantUserResponse); err != nil {
+					t.Fatalf("failed to encode response: %s", err)
+				}
+				return
+			}
+			if err := json.NewEncoder(w).Encode([]api.UserResponse{}); err != nil {
+				t.Fatalf("failed to encode response: %s", err)
+			}
+			return
+		case strings.Contains(r.URL.Path, "protocol"):
+			if r.URL.Path[len(r.URL.Path)-len(existingProtocol):] == existingProtocol {
+				if err := json.NewEncoder(w).Encode(wantProtocolResponse); err != nil {
+					t.Fatalf("failed to encode response: %s", err)
+				}
+				return
+			}
+			if err := json.NewEncoder(w).Encode(nil); err != nil {
+				t.Fatalf("failed to encode response: %s", err)
+			}
+			return
+		default:
+			t.Logf("hit location: %s", r.URL.Path)
+		}
+	}))
+
+	tmpDir := t.TempDir()
+	socket := path.Join(tmpDir, "socket")
+	l, err := net.Listen("unix", socket)
+	assert.NoError(t, err)
+	_ = srv.Listener.Close()
+	srv.Listener = l
+	srv.Start()
+	defer srv.Close()
+
+	cfg, ctx, tearDown := testrig.CreateConfig(t, test.DBTypeSQLite)
+	defer tearDown()
+
+	// Create a dummy application service
+	as := &config.ApplicationService{
+		ID:              "someID",
+		URL:             fmt.Sprintf("unix://%s", socket),
+		ASToken:         "",
+		HSToken:         "",
+		SenderLocalpart: "senderLocalPart",
+		NamespaceMap: map[string][]config.ApplicationServiceNamespace{
+			"users":   {{RegexpObject: regexp.MustCompile("as-.*")}},
+			"aliases": {{RegexpObject: regexp.MustCompile("asroom-.*")}},
+		},
+		Protocols: []string{existingProtocol},
+	}
+	as.CreateHTTPClient(cfg.AppServiceAPI.DisableTLSValidation)
+	cfg.AppServiceAPI.Derived.ApplicationServices = []config.ApplicationService{*as}
+
+	t.Cleanup(func() {
+		ctx.ShutdownDendrite()
+		ctx.WaitForShutdown()
+	})
+	caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
+	// Create required internal APIs
+	natsInstance := jetstream.NATSInstance{}
+	cm := sqlutil.NewConnectionManager(ctx, cfg.Global.DatabaseOptions)
+	rsAPI := roomserver.NewInternalAPI(ctx, cfg, cm, &natsInstance, caches, caching.DisableMetrics)
+	usrAPI := userapi.NewInternalAPI(ctx, cfg, cm, &natsInstance, rsAPI, nil)
+	asAPI := appservice.NewInternalAPI(ctx, cfg, &natsInstance, usrAPI, rsAPI)
+
+	t.Run("UserIDExists", func(t *testing.T) {
+		testUserIDExists(t, asAPI, "@as-testing:test", true)
+		testUserIDExists(t, asAPI, "@as1-testing:test", false)
+	})
+
+}
+
 func testUserIDExists(t *testing.T, asAPI api.AppServiceInternalAPI, userID string, wantExists bool) {
 	ctx := context.Background()
 	userResp := &api.UserIDExistsResponse{}
@@ -254,20 +356,21 @@ func TestRoomserverConsumerOneInvite(t *testing.T) {
 		}))
 		defer srv.Close()
 
-		// Create a dummy application service
-		cfg.AppServiceAPI.Derived.ApplicationServices = []config.ApplicationService{
-			{
-				ID:              "someID",
-				URL:             srv.URL,
-				ASToken:         "",
-				HSToken:         "",
-				SenderLocalpart: "senderLocalPart",
-				NamespaceMap: map[string][]config.ApplicationServiceNamespace{
-					"users":   {{RegexpObject: regexp.MustCompile(bob.ID)}},
-					"aliases": {{RegexpObject: regexp.MustCompile(room.ID)}},
-				},
+		as := &config.ApplicationService{
+			ID:              "someID",
+			URL:             srv.URL,
+			ASToken:         "",
+			HSToken:         "",
+			SenderLocalpart: "senderLocalPart",
+			NamespaceMap: map[string][]config.ApplicationServiceNamespace{
+				"users":   {{RegexpObject: regexp.MustCompile(bob.ID)}},
+				"aliases": {{RegexpObject: regexp.MustCompile(room.ID)}},
 			},
 		}
+		as.CreateHTTPClient(cfg.AppServiceAPI.DisableTLSValidation)
+
+		// Create a dummy application service
+		cfg.AppServiceAPI.Derived.ApplicationServices = []config.ApplicationService{*as}
 
 		caches := caching.NewRistrettoCache(128*1024*1024, time.Hour, caching.DisableMetrics)
 		// Create required internal APIs
diff --git a/appservice/consumers/roomserver.go b/appservice/consumers/roomserver.go
index 16b3b823..308b0367 100644
--- a/appservice/consumers/roomserver.go
+++ b/appservice/consumers/roomserver.go
@@ -40,7 +40,6 @@ import (
 type OutputRoomEventConsumer struct {
 	ctx       context.Context
 	cfg       *config.AppServiceAPI
-	client    *http.Client
 	jetstream nats.JetStreamContext
 	topic     string
 	rsAPI     api.AppserviceRoomserverAPI
@@ -56,14 +55,12 @@ type appserviceState struct {
 func NewOutputRoomEventConsumer(
 	process *process.ProcessContext,
 	cfg *config.AppServiceAPI,
-	client *http.Client,
 	js nats.JetStreamContext,
 	rsAPI api.AppserviceRoomserverAPI,
 ) *OutputRoomEventConsumer {
 	return &OutputRoomEventConsumer{
 		ctx:       process.Context(),
 		cfg:       cfg,
-		client:    client,
 		jetstream: js,
 		topic:     cfg.Matrix.JetStream.Prefixed(jetstream.OutputRoomEvent),
 		rsAPI:     rsAPI,
@@ -189,13 +186,13 @@ func (s *OutputRoomEventConsumer) sendEvents(
 
 	// Send the transaction to the appservice.
 	// https://matrix.org/docs/spec/application_service/r0.1.2#put-matrix-app-v1-transactions-txnid
-	address := fmt.Sprintf("%s/transactions/%s?access_token=%s", state.URL, txnID, url.QueryEscape(state.HSToken))
+	address := fmt.Sprintf("%s/transactions/%s?access_token=%s", state.RequestUrl(), txnID, url.QueryEscape(state.HSToken))
 	req, err := http.NewRequestWithContext(ctx, "PUT", address, bytes.NewBuffer(transaction))
 	if err != nil {
 		return err
 	}
 	req.Header.Set("Content-Type", "application/json")
-	resp, err := s.client.Do(req)
+	resp, err := state.HTTPClient.Do(req)
 	if err != nil {
 		return state.backoffAndPause(err)
 	}
@@ -206,7 +203,7 @@ func (s *OutputRoomEventConsumer) sendEvents(
 	case http.StatusOK:
 		state.backoff = 0
 	default:
-		return state.backoffAndPause(fmt.Errorf("received HTTP status code %d from appservice", resp.StatusCode))
+		return state.backoffAndPause(fmt.Errorf("received HTTP status code %d from appservice url %s", resp.StatusCode, address))
 	}
 	return nil
 }
diff --git a/appservice/query/query.go b/appservice/query/query.go
index 0466f81d..ca8d7b3a 100644
--- a/appservice/query/query.go
+++ b/appservice/query/query.go
@@ -37,7 +37,6 @@ const userIDExistsPath = "/users/"
 
 // AppServiceQueryAPI is an implementation of api.AppServiceQueryAPI
 type AppServiceQueryAPI struct {
-	HTTPClient    *http.Client
 	Cfg           *config.AppServiceAPI
 	ProtocolCache map[string]api.ASProtocolResponse
 	CacheMu       sync.Mutex
@@ -57,7 +56,7 @@ func (a *AppServiceQueryAPI) RoomAliasExists(
 	for _, appservice := range a.Cfg.Derived.ApplicationServices {
 		if appservice.URL != "" && appservice.IsInterestedInRoomAlias(request.Alias) {
 			// The full path to the rooms API, includes hs token
-			URL, err := url.Parse(appservice.URL + roomAliasExistsPath)
+			URL, err := url.Parse(appservice.RequestUrl() + roomAliasExistsPath)
 			if err != nil {
 				return err
 			}
@@ -73,7 +72,7 @@ func (a *AppServiceQueryAPI) RoomAliasExists(
 			}
 			req = req.WithContext(ctx)
 
-			resp, err := a.HTTPClient.Do(req)
+			resp, err := appservice.HTTPClient.Do(req)
 			if resp != nil {
 				defer func() {
 					err = resp.Body.Close()
@@ -124,7 +123,7 @@ func (a *AppServiceQueryAPI) UserIDExists(
 	for _, appservice := range a.Cfg.Derived.ApplicationServices {
 		if appservice.URL != "" && appservice.IsInterestedInUserID(request.UserID) {
 			// The full path to the rooms API, includes hs token
-			URL, err := url.Parse(appservice.URL + userIDExistsPath)
+			URL, err := url.Parse(appservice.RequestUrl() + userIDExistsPath)
 			if err != nil {
 				return err
 			}
@@ -137,7 +136,7 @@ func (a *AppServiceQueryAPI) UserIDExists(
 			if err != nil {
 				return err
 			}
-			resp, err := a.HTTPClient.Do(req.WithContext(ctx))
+			resp, err := appservice.HTTPClient.Do(req.WithContext(ctx))
 			if resp != nil {
 				defer func() {
 					err = resp.Body.Close()
@@ -212,12 +211,12 @@ func (a *AppServiceQueryAPI) Locations(
 		var asLocations []api.ASLocationResponse
 		params.Set("access_token", as.HSToken)
 
-		url := as.URL + api.ASLocationPath
+		url := as.RequestUrl() + api.ASLocationPath
 		if req.Protocol != "" {
 			url += "/" + req.Protocol
 		}
 
-		if err := requestDo[[]api.ASLocationResponse](a.HTTPClient, url+"?"+params.Encode(), &asLocations); err != nil {
+		if err := requestDo[[]api.ASLocationResponse](as.HTTPClient, url+"?"+params.Encode(), &asLocations); err != nil {
 			log.WithError(err).Error("unable to get 'locations' from application service")
 			continue
 		}
@@ -247,12 +246,12 @@ func (a *AppServiceQueryAPI) User(
 		var asUsers []api.ASUserResponse
 		params.Set("access_token", as.HSToken)
 
-		url := as.URL + api.ASUserPath
+		url := as.RequestUrl() + api.ASUserPath
 		if req.Protocol != "" {
 			url += "/" + req.Protocol
 		}
 
-		if err := requestDo[[]api.ASUserResponse](a.HTTPClient, url+"?"+params.Encode(), &asUsers); err != nil {
+		if err := requestDo[[]api.ASUserResponse](as.HTTPClient, url+"?"+params.Encode(), &asUsers); err != nil {
 			log.WithError(err).Error("unable to get 'user' from application service")
 			continue
 		}
@@ -290,7 +289,7 @@ func (a *AppServiceQueryAPI) Protocols(
 		response := api.ASProtocolResponse{}
 		for _, as := range a.Cfg.Derived.ApplicationServices {
 			var proto api.ASProtocolResponse
-			if err := requestDo[api.ASProtocolResponse](a.HTTPClient, as.URL+api.ASProtocolPath+req.Protocol, &proto); err != nil {
+			if err := requestDo[api.ASProtocolResponse](as.HTTPClient, as.RequestUrl()+api.ASProtocolPath+req.Protocol, &proto); err != nil {
 				log.WithError(err).Error("unable to get 'protocol' from application service")
 				continue
 			}
@@ -320,7 +319,7 @@ func (a *AppServiceQueryAPI) Protocols(
 	for _, as := range a.Cfg.Derived.ApplicationServices {
 		for _, p := range as.Protocols {
 			var proto api.ASProtocolResponse
-			if err := requestDo[api.ASProtocolResponse](a.HTTPClient, as.URL+api.ASProtocolPath+p, &proto); err != nil {
+			if err := requestDo[api.ASProtocolResponse](as.HTTPClient, as.RequestUrl()+api.ASProtocolPath+p, &proto); err != nil {
 				log.WithError(err).Error("unable to get 'protocol' from application service")
 				continue
 			}
diff --git a/setup/config/config_appservice.go b/setup/config/config_appservice.go
index 37e20a97..ef10649d 100644
--- a/setup/config/config_appservice.go
+++ b/setup/config/config_appservice.go
@@ -15,16 +15,23 @@
 package config
 
 import (
+	"context"
+	"crypto/tls"
 	"fmt"
+	"net"
+	"net/http"
 	"os"
 	"path/filepath"
 	"regexp"
 	"strings"
+	"time"
 
 	log "github.com/sirupsen/logrus"
 	"gopkg.in/yaml.v2"
 )
 
+const UnixSocketPrefix = "unix://"
+
 type AppServiceAPI struct {
 	Matrix  *Global  `yaml:"-"`
 	Derived *Derived `yaml:"-"` // TODO: Nuke Derived from orbit
@@ -80,7 +87,41 @@ type ApplicationService struct {
 	// Whether rate limiting is applied to each application service user
 	RateLimited bool `yaml:"rate_limited"`
 	// Any custom protocols that this application service provides (e.g. IRC)
-	Protocols []string `yaml:"protocols"`
+	Protocols    []string `yaml:"protocols"`
+	HTTPClient   *http.Client
+	isUnixSocket bool
+	unixSocket   string
+}
+
+func (a *ApplicationService) CreateHTTPClient(insecureSkipVerify bool) {
+	client := &http.Client{
+		Timeout: time.Second * 30,
+		Transport: &http.Transport{
+			DisableKeepAlives: true,
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: insecureSkipVerify,
+			},
+			Proxy: http.ProxyFromEnvironment,
+		},
+	}
+	if strings.HasPrefix(a.URL, UnixSocketPrefix) {
+		a.isUnixSocket = true
+		a.unixSocket = "http://unix"
+		client.Transport = &http.Transport{
+			DialContext: func(_ context.Context, _, _ string) (net.Conn, error) {
+				return net.Dial("unix", strings.TrimPrefix(a.URL, UnixSocketPrefix))
+			},
+		}
+	}
+	a.HTTPClient = client
+}
+
+func (a *ApplicationService) RequestUrl() string {
+	if a.isUnixSocket {
+		return a.unixSocket
+	} else {
+		return a.URL
+	}
 }
 
 // IsInterestedInRoomID returns a bool on whether an application service's
@@ -152,7 +193,7 @@ func (a *ApplicationService) IsInterestedInRoomAlias(
 func loadAppServices(config *AppServiceAPI, derived *Derived) error {
 	for _, configPath := range config.ConfigFiles {
 		// Create a new application service with default options
-		appservice := ApplicationService{
+		appservice := &ApplicationService{
 			RateLimited: true,
 		}
 
@@ -169,13 +210,13 @@ func loadAppServices(config *AppServiceAPI, derived *Derived) error {
 		}
 
 		// Load the config data into our struct
-		if err = yaml.Unmarshal(configData, &appservice); err != nil {
+		if err = yaml.Unmarshal(configData, appservice); err != nil {
 			return err
 		}
-
+		appservice.CreateHTTPClient(config.DisableTLSValidation)
 		// Append the parsed application service to the global config
 		derived.ApplicationServices = append(
-			derived.ApplicationServices, appservice,
+			derived.ApplicationServices, *appservice,
 		)
 	}