gotosocial/internal/ap/extract.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
// Package ap contains models and utilities for working with activitypub/activitystreams representations.
//
// It is built on top of go-fed/activity.
package ap
import (
"crypto"
"crypto/rsa"
"crypto/x509"
"encoding/pem"
"errors"
"fmt"
"net/url"
"strings"
"time"
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"github.com/superseriousbusiness/activity/pub"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
"github.com/superseriousbusiness/gotosocial/internal/util"
)
// ExtractPreferredUsername returns a string representation of an interface's preferredUsername property.
func ExtractPreferredUsername(i WithPreferredUsername) (string, error) {
u := i.GetActivityStreamsPreferredUsername()
if u == nil || !u.IsXMLSchemaString() {
return "", errors.New("preferredUsername was not a string")
}
if u.GetXMLSchemaString() == "" {
return "", errors.New("preferredUsername was empty")
}
return u.GetXMLSchemaString(), nil
}
// ExtractName returns a string representation of an interface's name property,
// or an empty string if this is not found.
func ExtractName(i WithName) string {
nameProp := i.GetActivityStreamsName()
if nameProp == nil {
return ""
}
// Take the first useful value for the name string we can find.
for iter := nameProp.Begin(); iter != nameProp.End(); iter = iter.Next() {
switch {
case iter.IsXMLSchemaString():
return iter.GetXMLSchemaString()
case iter.IsIRI():
return iter.GetIRI().String()
}
}
return ""
}
// ExtractInReplyToURI extracts the inReplyToURI property (if present) from an interface.
func ExtractInReplyToURI(i WithInReplyTo) *url.URL {
inReplyToProp := i.GetActivityStreamsInReplyTo()
if inReplyToProp == nil {
// the property just wasn't set
return nil
}
for iter := inReplyToProp.Begin(); iter != inReplyToProp.End(); iter = iter.Next() {
if iter.IsIRI() {
if iter.GetIRI() != nil {
return iter.GetIRI()
}
}
}
// couldn't find a URI
return nil
}
// ExtractURLItems extracts a slice of URLs from a property that has withItems.
func ExtractURLItems(i WithItems) []*url.URL {
urls := []*url.URL{}
items := i.GetActivityStreamsItems()
if items == nil || items.Len() == 0 {
return urls
}
for iter := items.Begin(); iter != items.End(); iter = iter.Next() {
if iter.IsIRI() {
urls = append(urls, iter.GetIRI())
}
}
return urls
}
// ExtractTos returns a list of URIs that the activity addresses as To.
func ExtractTos(i WithTo) ([]*url.URL, error) {
to := []*url.URL{}
toProp := i.GetActivityStreamsTo()
if toProp == nil {
return nil, errors.New("toProp was nil")
}
for iter := toProp.Begin(); iter != toProp.End(); iter = iter.Next() {
if iter.IsIRI() {
if iter.GetIRI() != nil {
to = append(to, iter.GetIRI())
}
}
}
return to, nil
}
// ExtractCCs returns a list of URIs that the activity addresses as CC.
func ExtractCCs(i WithCC) ([]*url.URL, error) {
cc := []*url.URL{}
ccProp := i.GetActivityStreamsCc()
if ccProp == nil {
return cc, nil
}
for iter := ccProp.Begin(); iter != ccProp.End(); iter = iter.Next() {
if iter.IsIRI() {
if iter.GetIRI() != nil {
cc = append(cc, iter.GetIRI())
}
}
}
return cc, nil
}
// ExtractAttributedTo returns the URL of the actor that the withAttributedTo is attributed to.
func ExtractAttributedTo(i WithAttributedTo) (*url.URL, error) {
attributedToProp := i.GetActivityStreamsAttributedTo()
if attributedToProp == nil {
return nil, errors.New("attributedToProp was nil")
}
for iter := attributedToProp.Begin(); iter != attributedToProp.End(); iter = iter.Next() {
if iter.IsIRI() {
if iter.GetIRI() != nil {
return iter.GetIRI(), nil
}
}
}
return nil, errors.New("couldn't find iri for attributed to")
}
// ExtractPublished extracts the publication time of an activity.
func ExtractPublished(i WithPublished) (time.Time, error) {
publishedProp := i.GetActivityStreamsPublished()
if publishedProp == nil {
return time.Time{}, errors.New("published prop was nil")
}
if !publishedProp.IsXMLSchemaDateTime() {
return time.Time{}, errors.New("published prop was not date time")
}
t := publishedProp.Get()
if t.IsZero() {
return time.Time{}, errors.New("published time was zero")
}
return t, nil
}
// ExtractIconURL extracts a URL to a supported image file from something like:
//
// "icon": {
// "mediaType": "image/jpeg",
// "type": "Image",
// "url": "http://example.org/path/to/some/file.jpeg"
// },
func ExtractIconURL(i WithIcon) (*url.URL, error) {
iconProp := i.GetActivityStreamsIcon()
if iconProp == nil {
return nil, errors.New("icon property was nil")
}
// icon can potentially contain multiple entries, so we iterate through all of them
// here in order to find the first one that meets these criteria:
// 1. is an image
// 2. has a URL so we can grab it
for iter := iconProp.Begin(); iter != iconProp.End(); iter = iter.Next() {
// 1. is an image
if !iter.IsActivityStreamsImage() {
continue
}
imageValue := iter.GetActivityStreamsImage()
if imageValue == nil {
continue
}
// 2. has a URL so we can grab it
url, err := ExtractURL(imageValue)
if err == nil && url != nil {
return url, nil
}
}
// if we get to this point we didn't find an icon meeting our criteria :'(
return nil, errors.New("could not extract valid image from icon")
}
// ExtractImageURL extracts a URL to a supported image file from something like:
//
// "image": {
// "mediaType": "image/jpeg",
// "type": "Image",
// "url": "http://example.org/path/to/some/file.jpeg"
// },
func ExtractImageURL(i WithImage) (*url.URL, error) {
imageProp := i.GetActivityStreamsImage()
if imageProp == nil {
return nil, errors.New("icon property was nil")
}
// icon can potentially contain multiple entries, so we iterate through all of them
// here in order to find the first one that meets these criteria:
// 1. is an image
// 2. has a URL so we can grab it
for iter := imageProp.Begin(); iter != imageProp.End(); iter = iter.Next() {
// 1. is an image
if !iter.IsActivityStreamsImage() {
continue
}
imageValue := iter.GetActivityStreamsImage()
if imageValue == nil {
continue
}
// 2. has a URL so we can grab it
url, err := ExtractURL(imageValue)
if err == nil && url != nil {
return url, nil
}
}
// if we get to this point we didn't find an image meeting our criteria :'(
return nil, errors.New("could not extract valid image from image property")
}
// ExtractSummary extracts the summary/content warning of an interface.
// Will return an empty string if no summary was present.
func ExtractSummary(i WithSummary) string {
summaryProp := i.GetActivityStreamsSummary()
if summaryProp == nil || summaryProp.Len() == 0 {
// no summary to speak of
return ""
}
for iter := summaryProp.Begin(); iter != summaryProp.End(); iter = iter.Next() {
switch {
case iter.IsXMLSchemaString():
return iter.GetXMLSchemaString()
case iter.IsIRI():
return iter.GetIRI().String()
}
}
return ""
}
func ExtractFields(i WithAttachment) []*gtsmodel.Field {
attachmentProp := i.GetActivityStreamsAttachment()
if attachmentProp == nil {
// Nothing to do.
return nil
}
l := attachmentProp.Len()
if l == 0 {
// Nothing to do.
return nil
}
fields := make([]*gtsmodel.Field, 0, l)
for iter := attachmentProp.Begin(); iter != attachmentProp.End(); iter = iter.Next() {
if !iter.IsSchemaPropertyValue() {
continue
}
propertyValue := iter.GetSchemaPropertyValue()
if propertyValue == nil {
continue
}
nameProp := propertyValue.GetActivityStreamsName()
if nameProp == nil || nameProp.Len() != 1 {
continue
}
name := nameProp.At(0).GetXMLSchemaString()
if name == "" {
continue
}
valueProp := propertyValue.GetSchemaValue()
if valueProp == nil || !valueProp.IsXMLSchemaString() {
continue
}
value := valueProp.Get()
if value == "" {
continue
}
fields = append(fields, &gtsmodel.Field{
Name: name,
Value: value,
})
}
return fields
}
// ExtractDiscoverable extracts the Discoverable boolean of an interface.
func ExtractDiscoverable(i WithDiscoverable) (bool, error) {
if i.GetTootDiscoverable() == nil {
return false, errors.New("discoverable was nil")
}
return i.GetTootDiscoverable().Get(), nil
}
// ExtractURL extracts the URL property of an interface.
func ExtractURL(i WithURL) (*url.URL, error) {
urlProp := i.GetActivityStreamsUrl()
if urlProp == nil {
return nil, errors.New("url property was nil")
}
for iter := urlProp.Begin(); iter != urlProp.End(); iter = iter.Next() {
if iter.IsIRI() && iter.GetIRI() != nil {
return iter.GetIRI(), nil
}
}
return nil, errors.New("could not extract url")
}
// ExtractPublicKey extracts the public key, public key ID, and public
// key owner ID from an interface, or an error if something goes wrong.
func ExtractPublicKey(i WithPublicKey) (
*rsa.PublicKey, // pubkey
*url.URL, // pubkey ID
*url.URL, // pubkey owner
error,
) {
pubKeyProp := i.GetW3IDSecurityV1PublicKey()
if pubKeyProp == nil {
return nil, nil, nil, gtserror.New("public key property was nil")
}
for iter := pubKeyProp.Begin(); iter != pubKeyProp.End(); iter = iter.Next() {
if !iter.IsW3IDSecurityV1PublicKey() {
continue
}
pkey := iter.Get()
if pkey == nil {
continue
}
pubKeyID, err := pub.GetId(pkey)
if err != nil {
continue
}
pubKeyOwnerProp := pkey.GetW3IDSecurityV1Owner()
if pubKeyOwnerProp == nil {
continue
}
pubKeyOwner := pubKeyOwnerProp.GetIRI()
if pubKeyOwner == nil {
continue
}
pubKeyPemProp := pkey.GetW3IDSecurityV1PublicKeyPem()
if pubKeyPemProp == nil {
continue
}
pkeyPem := pubKeyPemProp.Get()
if pkeyPem == "" {
continue
}
block, _ := pem.Decode([]byte(pkeyPem))
if block == nil {
continue
}
var p crypto.PublicKey
switch block.Type {
case "PUBLIC KEY":
p, err = x509.ParsePKIXPublicKey(block.Bytes)
case "RSA PUBLIC KEY":
p, err = x509.ParsePKCS1PublicKey(block.Bytes)
default:
err = fmt.Errorf("unknown block type: %q", block.Type)
}
if err != nil {
err = gtserror.Newf("could not parse public key from block bytes: %w", err)
return nil, nil, nil, err
}
if p == nil {
return nil, nil, nil, gtserror.New("returned public key was empty")
}
pubKey, ok := p.(*rsa.PublicKey)
if !ok {
continue
}
return pubKey, pubKeyID, pubKeyOwner, nil
}
return nil, nil, nil, gtserror.New("couldn't find public key")
}
// ExtractContent returns a string representation of the interface's Content property,
// or an empty string if no Content is found.
func ExtractContent(i WithContent) string {
contentProperty := i.GetActivityStreamsContent()
if contentProperty == nil {
return ""
}
for iter := contentProperty.Begin(); iter != contentProperty.End(); iter = iter.Next() {
switch {
case iter.IsXMLSchemaString():
return iter.GetXMLSchemaString()
case iter.IsIRI():
return iter.GetIRI().String()
}
}
return ""
}
// ExtractAttachment returns a gts model of an attachment from an attachmentable interface.
func ExtractAttachment(i Attachmentable) (*gtsmodel.MediaAttachment, error) {
attachment := &gtsmodel.MediaAttachment{}
attachmentURL, err := ExtractURL(i)
if err != nil {
return nil, err
}
attachment.RemoteURL = attachmentURL.String()
mediaType := i.GetActivityStreamsMediaType()
if mediaType != nil {
attachment.File.ContentType = mediaType.Get()
}
attachment.Type = gtsmodel.FileTypeImage
attachment.Description = ExtractName(i)
attachment.Blurhash = ExtractBlurhash(i)
attachment.Processing = gtsmodel.ProcessingStatusReceived
return attachment, nil
}
// ExtractBlurhash extracts the blurhash value (if present) from a WithBlurhash interface.
func ExtractBlurhash(i WithBlurhash) string {
if i.GetTootBlurhash() == nil {
return ""
}
return i.GetTootBlurhash().Get()
}
// ExtractHashtags returns a slice of tags on the interface.
func ExtractHashtags(i WithTag) ([]*gtsmodel.Tag, error) {
tags := []*gtsmodel.Tag{}
tagsProp := i.GetActivityStreamsTag()
if tagsProp == nil {
return tags, nil
}
for iter := tagsProp.Begin(); iter != tagsProp.End(); iter = iter.Next() {
t := iter.GetType()
if t == nil {
continue
}
if t.GetTypeName() != "Hashtag" {
continue
}
hashtaggable, ok := t.(Hashtaggable)
if !ok {
continue
}
tag, err := ExtractHashtag(hashtaggable)
if err != nil {
continue
}
tags = append(tags, tag)
}
return tags, nil
}
// ExtractHashtag returns a gtsmodel tag from a hashtaggable.
func ExtractHashtag(i Hashtaggable) (*gtsmodel.Tag, error) {
tag := &gtsmodel.Tag{}
hrefProp := i.GetActivityStreamsHref()
if hrefProp == nil || !hrefProp.IsIRI() {
return nil, errors.New("no href prop")
}
tag.URL = hrefProp.GetIRI().String()
name := ExtractName(i)
if name == "" {
return nil, errors.New("name prop empty")
}
tag.Name = strings.TrimPrefix(name, "#")
return tag, nil
}
// ExtractEmojis returns a slice of emojis on the interface.
func ExtractEmojis(i WithTag) ([]*gtsmodel.Emoji, error) {
emojis := []*gtsmodel.Emoji{}
emojiMap := make(map[string]*gtsmodel.Emoji)
tagsProp := i.GetActivityStreamsTag()
if tagsProp == nil {
return emojis, nil
}
for iter := tagsProp.Begin(); iter != tagsProp.End(); iter = iter.Next() {
t := iter.GetType()
if t == nil {
continue
}
if t.GetTypeName() != "Emoji" {
continue
}
emojiable, ok := t.(Emojiable)
if !ok {
continue
}
emoji, err := ExtractEmoji(emojiable)
if err != nil {
continue
}
emojiMap[emoji.URI] = emoji
}
for _, emoji := range emojiMap {
emojis = append(emojis, emoji)
}
return emojis, nil
}
// ExtractEmoji ...
func ExtractEmoji(i Emojiable) (*gtsmodel.Emoji, error) {
emoji := &gtsmodel.Emoji{}
idProp := i.GetJSONLDId()
if idProp == nil || !idProp.IsIRI() {
return nil, errors.New("no id for emoji")
}
uri := idProp.GetIRI()
emoji.URI = uri.String()
emoji.Domain = uri.Host
name := ExtractName(i)
if name == "" {
return nil, errors.New("name prop empty")
}
emoji.Shortcode = strings.Trim(name, ":")
if i.GetActivityStreamsIcon() == nil {
return nil, errors.New("no icon for emoji")
}
imageURL, err := ExtractIconURL(i)
if err != nil {
return nil, errors.New("no url for emoji image")
}
emoji.ImageRemoteURL = imageURL.String()
// assume false for both to begin
emoji.Disabled = new(bool)
emoji.VisibleInPicker = new(bool)
updatedProp := i.GetActivityStreamsUpdated()
if updatedProp != nil && updatedProp.IsXMLSchemaDateTime() {
emoji.UpdatedAt = updatedProp.Get()
}
return emoji, nil
}
// ExtractMentions extracts a slice of gtsmodel Mentions from a WithTag interface.
func ExtractMentions(i WithTag) ([]*gtsmodel.Mention, error) {
mentions := []*gtsmodel.Mention{}
tagsProp := i.GetActivityStreamsTag()
if tagsProp == nil {
return mentions, nil
}
for iter := tagsProp.Begin(); iter != tagsProp.End(); iter = iter.Next() {
t := iter.GetType()
if t == nil {
continue
}
if t.GetTypeName() != "Mention" {
continue
}
mentionable, ok := t.(Mentionable)
if !ok {
return nil, errors.New("mention was not convertable to ap.Mentionable")
}
mention, err := ExtractMention(mentionable)
if err != nil {
return nil, err
}
mentions = append(mentions, mention)
}
return mentions, nil
}
// ExtractMention extracts a gts model mention from a Mentionable.
func ExtractMention(i Mentionable) (*gtsmodel.Mention, error) {
mention := &gtsmodel.Mention{}
mentionString := ExtractName(i)
if mentionString == "" {
return nil, errors.New("name prop empty")
}
// just make sure the mention string is valid so we can handle it properly later on...
if _, _, err := util.ExtractNamestringParts(mentionString); err != nil {
return nil, err
}
mention.NameString = mentionString
// the href prop should be the AP URI of a user we know, eg https://example.org/users/whatever_user
hrefProp := i.GetActivityStreamsHref()
if hrefProp == nil || !hrefProp.IsIRI() {
return nil, errors.New("no href prop")
}
mention.TargetAccountURI = hrefProp.GetIRI().String()
return mention, nil
}
// ExtractActor extracts the actor ID/IRI from an interface WithActor.
func ExtractActor(i WithActor) (*url.URL, error) {
actorProp := i.GetActivityStreamsActor()
if actorProp == nil {
return nil, errors.New("actor property was nil")
}
for iter := actorProp.Begin(); iter != actorProp.End(); iter = iter.Next() {
if iter.IsIRI() && iter.GetIRI() != nil {
return iter.GetIRI(), nil
}
}
return nil, errors.New("no iri found for actor prop")
}
// ExtractObject extracts the first URL object from a WithObject interface.
func ExtractObject(i WithObject) (*url.URL, error) {
objectProp := i.GetActivityStreamsObject()
if objectProp == nil {
return nil, errors.New("object property was nil")
}
for iter := objectProp.Begin(); iter != objectProp.End(); iter = iter.Next() {
if iter.IsIRI() && iter.GetIRI() != nil {
return iter.GetIRI(), nil
}
}
return nil, errors.New("no iri found for object prop")
}
// ExtractObjects extracts a slice of URL objects from a WithObject interface.
func ExtractObjects(i WithObject) ([]*url.URL, error) {
objectProp := i.GetActivityStreamsObject()
if objectProp == nil {
return nil, errors.New("object property was nil")
}
urls := make([]*url.URL, 0, objectProp.Len())
for iter := objectProp.Begin(); iter != objectProp.End(); iter = iter.Next() {
if iter.IsIRI() && iter.GetIRI() != nil {
urls = append(urls, iter.GetIRI())
}
}
return urls, nil
}
// ExtractVisibility extracts the gtsmodel.Visibility of a given addressable with a To and CC property.
//
// ActorFollowersURI is needed to check whether the visibility is FollowersOnly or not. The passed-in value
// should just be the string value representation of the followers URI of the actor who created the activity,
// eg https://example.org/users/whoever/followers.
func ExtractVisibility(addressable Addressable, actorFollowersURI string) (gtsmodel.Visibility, error) {
to, err := ExtractTos(addressable)
if err != nil {
return "", fmt.Errorf("deriveVisibility: error extracting TO values: %s", err)
}
cc, err := ExtractCCs(addressable)
if err != nil {
return "", fmt.Errorf("deriveVisibility: error extracting CC values: %s", err)
}
if len(to) == 0 && len(cc) == 0 {
return "", errors.New("deriveVisibility: message wasn't TO or CC anyone")
}
// for visibility derivation, we start by assuming most restrictive, and work our way to least restrictive
visibility := gtsmodel.VisibilityDirect
// if it's got followers in TO and it's not also CC'ed to public, it's followers only
if isFollowers(to, actorFollowersURI) {
visibility = gtsmodel.VisibilityFollowersOnly
}
// if it's CC'ed to public, it's unlocked
// mentioned SPECIFIC ACCOUNTS also get added to CC'es if it's not a direct message
if isPublic(cc) {
visibility = gtsmodel.VisibilityUnlocked
}
// if it's To public, it's just straight up public
if isPublic(to) {
visibility = gtsmodel.VisibilityPublic
}
return visibility, nil
}
// isPublic checks if at least one entry in the given uris slice equals
// the activitystreams public uri.
func isPublic(uris []*url.URL) bool {
for _, entry := range uris {
if strings.EqualFold(entry.String(), pub.PublicActivityPubIRI) {
return true
}
}
return false
}
// isFollowers checks if at least one entry in the given uris slice equals
// the given followersURI.
func isFollowers(uris []*url.URL, followersURI string) bool {
for _, entry := range uris {
if strings.EqualFold(entry.String(), followersURI) {
return true
}
}
return false
}
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// ExtractSensitive extracts whether or not an item is 'sensitive'.
// If no sensitive property is set on the item at all, or if this property
// isn't a boolean, then false will be returned by default.
func ExtractSensitive(withSensitive WithSensitive) bool {
sensitiveProp := withSensitive.GetActivityStreamsSensitive()
if sensitiveProp == nil {
return false
}
for iter := sensitiveProp.Begin(); iter != sensitiveProp.End(); iter = iter.Next() {
if iter.IsXMLSchemaBoolean() {
return iter.Get()
}
}
return false
}
// ExtractSharedInbox extracts the sharedInbox URI properly from an Actor.
// Returns nil if this property is not set.
func ExtractSharedInbox(withEndpoints WithEndpoints) *url.URL {
endpointsProp := withEndpoints.GetActivityStreamsEndpoints()
if endpointsProp == nil {
return nil
}
for iter := endpointsProp.Begin(); iter != endpointsProp.End(); iter = iter.Next() {
if iter.IsActivityStreamsEndpoints() {
endpoints := iter.Get()
if endpoints == nil {
return nil
}
sharedInboxProp := endpoints.GetActivityStreamsSharedInbox()
if sharedInboxProp == nil {
return nil
}
if !sharedInboxProp.IsIRI() {
return nil
}
return sharedInboxProp.GetIRI()
}
}
return nil
}