1 files changed, 216 insertions, 0 deletions
diff --git a/internal/typeutils/asextractionutil.go b/internal/typeutils/asextractionutil.go
new file mode 100644
index 000000000..8d39be3ec
--- /dev/null
+++ b/internal/typeutils/asextractionutil.go
@@ -0,0 +1,216 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   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 typeutils
+
+import (
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"net/url"
+
+	"github.com/go-fed/activity/pub"
+)
+
+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
+}
+
+func extractName(i withDisplayName) (string, error) {
+	nameProp := i.GetActivityStreamsName()
+	if nameProp == nil {
+		return "", errors.New("activityStreamsName not found")
+	}
+
+	// take the first name string we can find
+	for nameIter := nameProp.Begin(); nameIter != nameProp.End(); nameIter = nameIter.Next() {
+		if nameIter.IsXMLSchemaString() && nameIter.GetXMLSchemaString() != "" {
+			return nameIter.GetXMLSchemaString(), nil
+		}
+	}
+
+	return "", errors.New("activityStreamsName not found")
+}
+
+// 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 iconIter := iconProp.Begin(); iconIter != iconProp.End(); iconIter = iconIter.Next() {
+		// 1. is an image
+		if !iconIter.IsActivityStreamsImage() {
+			continue
+		}
+		imageValue := iconIter.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 imageIter := imageProp.Begin(); imageIter != imageProp.End(); imageIter = imageIter.Next() {
+		// 1. is an image
+		if !imageIter.IsActivityStreamsImage() {
+			continue
+		}
+		imageValue := imageIter.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")
+}
+
+func extractSummary(i withSummary) (string, error) {
+	summaryProp := i.GetActivityStreamsSummary()
+	if summaryProp == nil {
+		return "", errors.New("summary property was nil")
+	}
+
+	for summaryIter := summaryProp.Begin(); summaryIter != summaryProp.End(); summaryIter = summaryIter.Next() {
+		if summaryIter.IsXMLSchemaString() && summaryIter.GetXMLSchemaString() != "" {
+			return summaryIter.GetXMLSchemaString(), nil
+		}
+	}
+
+	return "", errors.New("could not extract summary")
+}
+
+func extractDiscoverable(i withDiscoverable) (bool, error) {
+	if i.GetTootDiscoverable() == nil {
+		return false, errors.New("discoverable was nil")
+	}
+	return i.GetTootDiscoverable().Get(), nil
+}
+
+func extractURL(i withURL) (*url.URL, error) {
+	urlProp := i.GetActivityStreamsUrl()
+	if urlProp == nil {
+		return nil, errors.New("url property was nil")
+	}
+
+	for urlIter := urlProp.Begin(); urlIter != urlProp.End(); urlIter = urlIter.Next() {
+		if urlIter.IsIRI() && urlIter.GetIRI() != nil {
+			return urlIter.GetIRI(), nil
+		}
+	}
+
+	return nil, errors.New("could not extract url")
+}
+
+func extractPublicKeyForOwner(i withPublicKey, forOwner *url.URL) (*rsa.PublicKey, *url.URL, error) {
+	publicKeyProp := i.GetW3IDSecurityV1PublicKey()
+	if publicKeyProp == nil {
+		return nil, nil, errors.New("public key property was nil")
+	}
+
+	for publicKeyIter := publicKeyProp.Begin(); publicKeyIter != publicKeyProp.End(); publicKeyIter = publicKeyIter.Next() {
+		pkey := publicKeyIter.Get()
+		if pkey == nil {
+			continue
+		}
+
+		pkeyID, err := pub.GetId(pkey)
+		if err != nil || pkeyID == nil {
+			continue
+		}
+
+		if pkey.GetW3IDSecurityV1Owner() == nil || pkey.GetW3IDSecurityV1Owner().Get() == nil || pkey.GetW3IDSecurityV1Owner().Get().String() != forOwner.String() {
+			continue
+		}
+
+		if pkey.GetW3IDSecurityV1PublicKeyPem() == nil {
+			continue
+		}
+
+		pkeyPem := pkey.GetW3IDSecurityV1PublicKeyPem().Get()
+		if pkeyPem == "" {
+			continue
+		}
+
+		block, _ := pem.Decode([]byte(pkeyPem))
+		if block == nil || block.Type != "PUBLIC KEY" {
+			return nil, nil, errors.New("could not decode publicKeyPem to PUBLIC KEY pem block type")
+		}
+
+		p, err := x509.ParsePKIXPublicKey(block.Bytes)
+		if err != nil {
+			return nil, nil, fmt.Errorf("could not parse public key from block bytes: %s", err)
+		}
+		if p == nil {
+			return nil, nil, errors.New("returned public key was empty")
+		}
+
+		if publicKey, ok := p.(*rsa.PublicKey); ok {
+			return publicKey, pkeyID, nil
+		}
+	}
+	return nil, nil, errors.New("couldn't find public key")
+}