User keypairs and HTTP signatures for ActivityPub federation using go-ap

custom/conf/app.example.ini

@@ -2253,6 +2253,23 @@ PATH =
 ;;
 ;; Enable/Disable user statistics for nodeinfo if federation is enabled
 ; SHARE_USER_STATISTICS = true
+;;
+;; Maximum federation request and response size (MB)
+; MAX_SIZE = 4
+;;
+;; WARNING: Changing the settings below can break federation.
+;;
+;; HTTP signature algorithms
+; ALGORITHMS = rsa-sha256, rsa-sha512, ed25519
+;;
+;; HTTP signature digest algorithm
+; DIGEST_ALGORITHM = SHA-256
+;;
+;; GET headers for federation requests
+; GET_HEADERS = (request-target), Date
+;;
+;; POST headers for federation requests
+; POST_HEADERS = (request-target), Date, Digest
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -1090,6 +1090,14 @@ Task queue configuration has been moved to `queue.task`. However, the below conf
 
 - `ENABLED`: **true**: Enable/Disable federation capabilities
 - `SHARE_USER_STATISTICS`: **true**: Enable/Disable user statistics for nodeinfo if federation is enabled
+- `MAX_SIZE`: **4**: Maximum federation request and response size (MB)
+
+ WARNING: Changing the settings below can break federation.
+
+- `ALGORITHMS`: **rsa-sha256, rsa-sha512, ed25519**: HTTP signature algorithms
+- `DIGEST_ALGORITHM`: **SHA-256**: HTTP signature digest algorithm
+- `GET_HEADERS`: **(request-target), Date**: GET headers for federation requests
+- `POST_HEADERS`: **(request-target), Date, Digest**: POST headers for federation requests
 
 ## Packages (`packages`)
 

go.mod

@@ -28,10 +28,12 @@ require (
 	github.com/ethantkoenig/rupture v1.0.1
 	github.com/felixge/fgprof v0.9.2
 	github.com/gliderlabs/ssh v0.3.4
+	github.com/go-ap/activitypub v0.0.0-20220615144428-48208c70483b
+	github.com/go-ap/jsonld v0.0.0-20220615144122-1d862b15410d
 	github.com/go-chi/chi/v5 v5.0.7
 	github.com/go-chi/cors v1.2.1
 	github.com/go-enry/go-enry/v2 v2.8.2
-	github.com/go-fed/httpsig v1.1.0
+	github.com/go-fed/httpsig v1.1.1-0.20201223112313-55836744818e
 	github.com/go-git/go-billy/v5 v5.3.1
 	github.com/go-git/go-git/v5 v5.4.3-0.20210630082519-b4368b2a2ca4
 	github.com/go-ldap/ldap/v3 v3.4.3
@@ -107,6 +109,7 @@ require (
 
 require (
 	cloud.google.com/go v0.99.0 // indirect
+	git.sr.ht/~mariusor/go-xsd-duration v0.0.0-20200411073322-f0bcc40f0bf2 // indirect
 	github.com/Azure/go-ntlmssp v0.0.0-20211209120228-48547f28849e // indirect
 	github.com/Microsoft/go-winio v0.5.2 // indirect
 	github.com/ProtonMail/go-crypto v0.0.0-20220407094043-a94812496cf5 // indirect
@@ -160,6 +163,7 @@ require (
 	github.com/fsnotify/fsnotify v1.5.4 // indirect
 	github.com/fullstorydev/grpcurl v1.8.1 // indirect
 	github.com/fxamacker/cbor/v2 v2.4.0 // indirect
+	github.com/go-ap/errors v0.0.0-20220615144307-e8bc4a40ae9f // indirect
 	github.com/go-asn1-ber/asn1-ber v1.5.4 // indirect
 	github.com/go-enry/go-oniguruma v1.2.1 // indirect
 	github.com/go-git/gcfg v1.5.0 // indirect
@@ -252,6 +256,7 @@ require (
 	github.com/toqueteos/webbrowser v1.2.0 // indirect
 	github.com/ulikunitz/xz v0.5.10 // indirect
 	github.com/unknwon/com v1.0.1 // indirect
+	github.com/valyala/fastjson v1.6.3 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	github.com/xanzy/ssh-agent v0.3.1 // indirect
 	github.com/xi2/xz v0.0.0-20171230120015-48954b6210f8 // indirect

go.sum

@@ -69,6 +69,8 @@ contrib.go.opencensus.io/exporter/stackdriver v0.13.5/go.mod h1:aXENhDJ1Y4lIg4EU
 contrib.go.opencensus.io/integrations/ocsql v0.1.4/go.mod h1:8DsSdjz3F+APR+0z0WkU1aRorQCFfRxvqjUUPMbF3fE=
 contrib.go.opencensus.io/resource v0.1.1/go.mod h1:F361eGI91LCmW1I/Saf+rX0+OFcigGlFvXwEGEnkRLA=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
+git.sr.ht/~mariusor/go-xsd-duration v0.0.0-20200411073322-f0bcc40f0bf2 h1:2OrsyJYZp7J6nyAsKi2q1SELYRaIc0aQmcQ/EQqPfk8=
+git.sr.ht/~mariusor/go-xsd-duration v0.0.0-20200411073322-f0bcc40f0bf2/go.mod h1:g/V2Hjas6Z1UHUp4yIx6bATpNzJ7DYtD0FG3+xARWxs=
 gitea.com/go-chi/binding v0.0.0-20220309004920-114340dabecb h1:Yy0Bxzc8R2wxiwXoG/rECGplJUSpXqCsog9PuJFgiHs=
 gitea.com/go-chi/binding v0.0.0-20220309004920-114340dabecb/go.mod h1:77TZu701zMXWJFvB8gvTbQ92zQ3DQq/H7l5wAEjQRKc=
 gitea.com/go-chi/cache v0.0.0-20210110083709-82c4c9ce2d5e/go.mod h1:k2V/gPDEtXGjjMGuBJiapffAXTv76H4snSmlJRLUhH0=
@@ -460,6 +462,12 @@ github.com/globalsign/mgo v0.0.0-20180905125535-1ca0a4f7cbcb/go.mod h1:xkRDCp4j0
 github.com/globalsign/mgo v0.0.0-20181015135952-eeefdecb41b8/go.mod h1:xkRDCp4j0OGD1HRkm4kmhM+pmpv3AKq5SU7GMg4oO/Q=
 github.com/glycerine/go-unsnap-stream v0.0.0-20181221182339-f9677308dec2/go.mod h1:/20jfyN9Y5QPEAprSgKAUr+glWDY39ZiUEAYOEv5dsE=
 github.com/glycerine/goconvey v0.0.0-20190410193231-58a59202ab31/go.mod h1:Ogl1Tioa0aV7gstGFO7KhffUsb9M4ydbEbbxpcEDc24=
+github.com/go-ap/activitypub v0.0.0-20220615144428-48208c70483b h1:+RjYfEfoZdM3wHFs752dlOpGaoRhwRRyQxjajg08LcQ=
+github.com/go-ap/activitypub v0.0.0-20220615144428-48208c70483b/go.mod h1:DE3vvc6Didgfd3k7M1Mos6qMDFNmMrxJmYVMHG9h9Io=
+github.com/go-ap/errors v0.0.0-20220615144307-e8bc4a40ae9f h1:kJhGo4NApJP0Lt9lkJnfmuTnRWVFbCynY0kiTxpPUR4=
+github.com/go-ap/errors v0.0.0-20220615144307-e8bc4a40ae9f/go.mod h1:KHkKFKZvc05lr79+RGoq/zG8YjWi3+FK60Bxd+mpCew=
+github.com/go-ap/jsonld v0.0.0-20220615144122-1d862b15410d h1:Z/oRXMlZHjvjIqDma1FrIGL3iE5YL7MUI0bwYEZ6qbA=
+github.com/go-ap/jsonld v0.0.0-20220615144122-1d862b15410d/go.mod h1:jyveZeGw5LaADntW+UEsMjl3IlIwk+DxlYNsbofQkGA=
 github.com/go-asn1-ber/asn1-ber v1.5.4 h1:vXT6d/FNDiELJnLb6hGNa309LMsrCoYFvpwHDF0+Y1A=
 github.com/go-asn1-ber/asn1-ber v1.5.4/go.mod h1:hEBeB/ic+5LoWskz+yKT7vGhhPYkProFKoKdwZRWMe0=
 github.com/go-chi/chi/v5 v5.0.1/go.mod h1:DslCQbL2OYiznFReuXYUmQ2hGd1aDpCnlMNITLSKoi8=
@@ -472,8 +480,8 @@ github.com/go-enry/go-enry/v2 v2.8.2 h1:uiGmC+3K8sVd/6DOe2AOJEOihJdqda83nPyJNtMR
 github.com/go-enry/go-enry/v2 v2.8.2/go.mod h1:GVzIiAytiS5uT/QiuakK7TF1u4xDab87Y8V5EJRpsIQ=
 github.com/go-enry/go-oniguruma v1.2.1 h1:k8aAMuJfMrqm/56SG2lV9Cfti6tC4x8673aHCcBk+eo=
 github.com/go-enry/go-oniguruma v1.2.1/go.mod h1:bWDhYP+S6xZQgiRL7wlTScFYBe023B6ilRZbCAD5Hf4=
-github.com/go-fed/httpsig v1.1.0 h1:9M+hb0jkEICD8/cAiNqEB66R87tTINszBRTjwjQzWcI=
-github.com/go-fed/httpsig v1.1.0/go.mod h1:RCMrTZvN1bJYtofsG4rd5NaO5obxQ5xBkdiS7xsT7bM=
+github.com/go-fed/httpsig v1.1.1-0.20201223112313-55836744818e h1:oRq/fiirun5HqlEWMLIcDmLpIELlG4iGbd0s8iqgPi8=
+github.com/go-fed/httpsig v1.1.1-0.20201223112313-55836744818e/go.mod h1:RCMrTZvN1bJYtofsG4rd5NaO5obxQ5xBkdiS7xsT7bM=
 github.com/go-git/gcfg v1.5.0 h1:Q5ViNfGF8zFgyJWPqYwA7qGFoMTEiBmdlkcfRmpIMa4=
 github.com/go-git/gcfg v1.5.0/go.mod h1:5m20vg6GwYabIxaOonVkTdrILxQMpEShl1xiMF4ua+E=
 github.com/go-git/go-billy/v5 v5.2.0/go.mod h1:pmpqyWchKfYfrkb/UVH4otLvyi/5gJlGI4Hb3ZqZ3W0=
@@ -1507,6 +1515,8 @@ github.com/urfave/cli v1.22.9 h1:cv3/KhXGBGjEXLC4bH0sLuJ9BewaAbpk5oyMOveu4pw=
 github.com/urfave/cli v1.22.9/go.mod h1:Gos4lmkARVdJ6EkW0WaNv/tZAAMe9V7XWyB60NtXRu0=
 github.com/urfave/cli/v2 v2.2.0/go.mod h1:SE9GqnLQmjVa0iPEY0f1w3ygNIYcIJ0OKPMoW2caLfQ=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
+github.com/valyala/fastjson v1.6.3 h1:tAKFnnwmeMGPbwJ7IwxcTPCNr3uIzoIj3/Fh90ra4xc=
+github.com/valyala/fastjson v1.6.3/go.mod h1:CLCAqky6SMuOcxStkYQvblddUtoRxhYMGLrsQns1aXY=
 github.com/valyala/fasttemplate v1.0.1/go.mod h1:UQGH1tvbgY+Nz5t2n7tXsz52dQxojPUpymEIMZ47gx8=
 github.com/vektah/gqlparser v1.1.2/go.mod h1:1ycwN7Ij5njmMkPPAOaRFY4rET2Enx7IkVv3vaXspKw=
 github.com/weppos/publicsuffix-go v0.13.1-0.20210123135404-5fd73613514e/go.mod h1:HYux0V0Zi04bHNwOHy4cXJVz/TQjYonnF6aoYhj+3QE=

integrations/api_activitypub_person_test.go

@@ -0,0 +1,103 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package integrations
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/activitypub"
+	"code.gitea.io/gitea/modules/setting"
+
+	ap "github.com/go-ap/activitypub"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestActivityPubPerson(t *testing.T) {
+	onGiteaRun(t, func(*testing.T, *url.URL) {
+		setting.Federation.Enabled = true
+		defer func() {
+			setting.Federation.Enabled = false
+		}()
+
+		username := "user2"
+		req := NewRequestf(t, "GET", fmt.Sprintf("/api/v1/activitypub/user/%s", username))
+		resp := MakeRequest(t, req, http.StatusOK)
+		body := resp.Body.Bytes()
+		assert.Contains(t, string(body), "@context")
+
+		var person ap.Person
+		err := person.UnmarshalJSON(body)
+		assert.NoError(t, err)
+
+		assert.Equal(t, ap.PersonType, person.Type)
+		assert.Equal(t, username, person.PreferredUsername.String())
+		keyID := person.GetID().String()
+		assert.Regexp(t, fmt.Sprintf("activitypub/user/%s$", username), keyID)
+		assert.Regexp(t, fmt.Sprintf("activitypub/user/%s/outbox$", username), person.Outbox.GetID().String())
+		assert.Regexp(t, fmt.Sprintf("activitypub/user/%s/inbox$", username), person.Inbox.GetID().String())
+
+		pubKey := person.PublicKey
+		assert.NotNil(t, pubKey)
+		publicKeyID := keyID + "#main-key"
+		assert.Equal(t, pubKey.ID.String(), publicKeyID)
+
+		pubKeyPem := pubKey.PublicKeyPem
+		assert.NotNil(t, pubKeyPem)
+		assert.Regexp(t, "^-----BEGIN PUBLIC KEY-----", pubKeyPem)
+	})
+}
+
+func TestActivityPubMissingPerson(t *testing.T) {
+	onGiteaRun(t, func(*testing.T, *url.URL) {
+		setting.Federation.Enabled = true
+		defer func() {
+			setting.Federation.Enabled = false
+		}()
+
+		req := NewRequestf(t, "GET", "/api/v1/activitypub/user/nonexistentuser")
+		resp := MakeRequest(t, req, http.StatusNotFound)
+		assert.Contains(t, resp.Body.String(), "user redirect does not exist")
+	})
+}
+
+func TestActivityPubPersonInbox(t *testing.T) {
+	srv := httptest.NewServer(c)
+	defer srv.Close()
+
+	onGiteaRun(t, func(*testing.T, *url.URL) {
+		appURL := setting.AppURL
+		setting.Federation.Enabled = true
+		setting.AppURL = srv.URL
+		defer func() {
+			setting.Federation.Enabled = false
+			setting.Database.LogSQL = false
+			setting.AppURL = appURL
+		}()
+		username1 := "user1"
+		ctx := context.Background()
+		user1, err := user_model.GetUserByName(ctx, username1)
+		assert.NoError(t, err)
+		user1url := fmt.Sprintf("%s/api/v1/activitypub/user/%s#main-key", srv.URL, username1)
+		c, err := activitypub.NewClient(user1, user1url)
+		assert.NoError(t, err)
+		username2 := "user2"
+		user2inboxurl := fmt.Sprintf("%s/api/v1/activitypub/user/%s/inbox", srv.URL, username2)
+
+		// Signed request succeeds
+		resp, err := c.Post([]byte{}, user2inboxurl)
+		assert.NoError(t, err)
+		assert.Equal(t, http.StatusNoContent, resp.StatusCode)
+
+		// Unsigned request fails
+		req := NewRequest(t, "POST", user2inboxurl)
+		MakeRequest(t, req, http.StatusInternalServerError)
+	})
+}

integrations/webfinger_test.go

@@ -52,7 +52,7 @@ func TestWebfinger(t *testing.T) {
 	var jrd webfingerJRD
 	DecodeJSON(t, resp, &jrd)
 	assert.Equal(t, "acct:user2@"+appURL.Host, jrd.Subject)
-	assert.ElementsMatch(t, []string{user.HTMLURL()}, jrd.Aliases)
+	assert.ElementsMatch(t, []string{user.HTMLURL(), appURL.String() + "api/v1/activitypub/user/" + url.PathEscape(user.Name)}, jrd.Aliases)
 
 	req = NewRequest(t, "GET", fmt.Sprintf("/.well-known/webfinger?resource=acct:%s@%s", user.LowerName, "unknown.host"))
 	MakeRequest(t, req, http.StatusBadRequest)

models/user/setting_keys.go

@@ -9,4 +9,8 @@ const (
 	SettingsKeyHiddenCommentTypes = "issue.hidden_comment_types"
 	// SettingsKeyDiffWhitespaceBehavior is the setting key for whitespace behavior of diff
 	SettingsKeyDiffWhitespaceBehavior = "diff.whitespace_behaviour"
+	// UserActivityPubPrivPem is user's private key
+	UserActivityPubPrivPem = "activitypub.priv_pem"
+	// UserActivityPubPubPem is user's public key
+	UserActivityPubPubPem = "activitypub.pub_pem"
 )

modules/activitypub/client.go

@@ -0,0 +1,124 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package activitypub
+
+import (
+	"bytes"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/proxy"
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/go-fed/httpsig"
+)
+
+const (
+	// ActivityStreamsContentType const
+	ActivityStreamsContentType = `application/ld+json; profile="https://www.w3.org/ns/activitystreams"`
+	httpsigExpirationTime      = 60
+)
+
+// Gets the current time as an RFC 2616 formatted string
+// RFC 2616 requires RFC 1123 dates but with GMT instead of UTC
+func CurrentTime() string {
+	return strings.ReplaceAll(time.Now().UTC().Format(time.RFC1123), "UTC", "GMT")
+}
+
+func containsRequiredHTTPHeaders(method string, headers []string) error {
+	var hasRequestTarget, hasDate, hasDigest bool
+	for _, header := range headers {
+		hasRequestTarget = hasRequestTarget || header == httpsig.RequestTarget
+		hasDate = hasDate || header == "Date"
+		hasDigest = hasDigest || header == "Digest"
+	}
+	if !hasRequestTarget {
+		return fmt.Errorf("missing http header for %s: %s", method, httpsig.RequestTarget)
+	} else if !hasDate {
+		return fmt.Errorf("missing http header for %s: Date", method)
+	} else if !hasDigest && method != http.MethodGet {
+		return fmt.Errorf("missing http header for %s: Digest", method)
+	}
+	return nil
+}
+
+// Client struct
+type Client struct {
+	client      *http.Client
+	algs        []httpsig.Algorithm
+	digestAlg   httpsig.DigestAlgorithm
+	getHeaders  []string
+	postHeaders []string
+	priv        *rsa.PrivateKey
+	pubID       string
+}
+
+// NewClient function
+func NewClient(user *user_model.User, pubID string) (c *Client, err error) {
+	if err = containsRequiredHTTPHeaders(http.MethodGet, setting.Federation.GetHeaders); err != nil {
+		return
+	} else if err = containsRequiredHTTPHeaders(http.MethodPost, setting.Federation.PostHeaders); err != nil {
+		return
+	}
+
+	priv, err := GetPrivateKey(user)
+	if err != nil {
+		return
+	}
+	privPem, _ := pem.Decode([]byte(priv))
+	privParsed, err := x509.ParsePKCS1PrivateKey(privPem.Bytes)
+	if err != nil {
+		return
+	}
+
+	c = &Client{
+		client: &http.Client{
+			Transport: &http.Transport{
+				Proxy: proxy.Proxy(),
+			},
+		},
+		algs:        setting.HttpsigAlgs,
+		digestAlg:   httpsig.DigestAlgorithm(setting.Federation.DigestAlgorithm),
+		getHeaders:  setting.Federation.GetHeaders,
+		postHeaders: setting.Federation.PostHeaders,
+		priv:        privParsed,
+		pubID:       pubID,
+	}
+	return
+}
+
+// NewRequest function
+func (c *Client) NewRequest(b []byte, to string) (req *http.Request, err error) {
+	buf := bytes.NewBuffer(b)
+	req, err = http.NewRequest(http.MethodPost, to, buf)
+	if err != nil {
+		return
+	}
+	req.Header.Add("Content-Type", ActivityStreamsContentType)
+	req.Header.Add("Date", CurrentTime())
+	req.Header.Add("User-Agent", "Gitea/"+setting.AppVer)
+	signer, _, err := httpsig.NewSigner(c.algs, c.digestAlg, c.postHeaders, httpsig.Signature, httpsigExpirationTime)
+	if err != nil {
+		return
+	}
+	err = signer.SignRequest(c.priv, c.pubID, req, b)
+	return
+}
+
+// Post function
+func (c *Client) Post(b []byte, to string) (resp *http.Response, err error) {
+	var req *http.Request
+	if req, err = c.NewRequest(b, to); err != nil {
+		return
+	}
+	resp, err = c.client.Do(req)
+	return
+}