Implement attachments for Discord -> Matrix

bridge/attachments.go

@@ -0,0 +1,60 @@
+package bridge
+
+import (
+	"bytes"
+	"image"
+	"io/ioutil"
+	"net/http"
+	"strings"
+
+	"github.com/bwmarrin/discordgo"
+
+	"maunium.net/go/mautrix/appservice"
+	"maunium.net/go/mautrix/event"
+)
+
+func (p *Portal) downloadDiscordAttachment(url string) ([]byte, error) {
+	// We might want to make this save to disk in the future. Discord defaults
+	// to 8mb for all attachments to a messages for non-nitro users and
+	// non-boosted servers.
+	//
+	// If the user has nitro classic, their limit goes up to 50mb but if a user
+	// has regular nitro the limit is increased to 100mb.
+	//
+	// Servers boosted to level 2 will have the limit bumped to 50mb.
+
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("User-Agent", discordgo.DroidBrowserUserAgent)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+
+	return ioutil.ReadAll(resp.Body)
+}
+
+func (p *Portal) uploadMatrixAttachment(intent *appservice.IntentAPI, data []byte, content *event.MessageEventContent) error {
+	uploaded, err := intent.UploadBytes(data, content.Info.MimeType)
+	if err != nil {
+		return err
+	}
+
+	content.URL = uploaded.ContentURI.CUString()
+
+	content.Info.Size = len(data)
+
+	if content.Info.Width == 0 && content.Info.Height == 0 && strings.HasPrefix(content.Info.MimeType, "image/") {
+		cfg, _, _ := image.DecodeConfig(bytes.NewReader(data))
+		content.Info.Width = cfg.Width
+		content.Info.Height = cfg.Height
+	}
+
+	return nil
+}