From 4ac636670684f0b070455585b6b9c94973ccba43 Mon Sep 17 00:00:00 2001
From: Alexander <papatutuwawa@polynom.me>
Date: Thu, 21 Jan 2021 22:50:04 +0100
Subject: [PATCH] Allow the XMPP bridge to use slack compatible webhooks (xmpp)
 (#1364)

* Add mod_slack_webhook support to the XMPP bridge

* Replace b.webhookURL with b.GetString

* Do not return a message ID on webhook POST

* Add the XMPP webhook to the sample configuration
---
 bridge/xmpp/xmpp.go      | 57 +++++++++++++++++++++++++++++++++++-----
 matterbridge.toml.sample |  5 ++++
 2 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/bridge/xmpp/xmpp.go b/bridge/xmpp/xmpp.go
index 45c5beb0..e92c3d69 100644
--- a/bridge/xmpp/xmpp.go
+++ b/bridge/xmpp/xmpp.go
@@ -1,8 +1,11 @@
 package bxmpp
 
 import (
+	"bytes"
 	"crypto/tls"
+	"encoding/json"
 	"fmt"
+	"net/http"
 	"strings"
 	"sync"
 	"time"
@@ -86,14 +89,21 @@ func (b *Bxmpp) Send(msg config.Message) (string, error) {
 	}
 
 	// Upload a file (in XMPP case send the upload URL because XMPP has no native upload support).
+	var err error
 	if msg.Extra != nil {
 		for _, rmsg := range helper.HandleExtra(&msg, b.General) {
 			b.Log.Debugf("=> Sending attachement message %#v", rmsg)
-			if _, err := b.xc.Send(xmpp.Chat{
-				Type:   "groupchat",
-				Remote: rmsg.Channel + "@" + b.GetString("Muc"),
-				Text:   rmsg.Username + rmsg.Text,
-			}); err != nil {
+			if b.GetString("WebhookURL") != "" {
+				err = b.postSlackCompatibleWebhook(msg)
+			} else {
+				_, err = b.xc.Send(xmpp.Chat{
+					Type:   "groupchat",
+					Remote: rmsg.Channel + "@" + b.GetString("Muc"),
+					Text:   rmsg.Username + rmsg.Text,
+				})
+			}
+
+			if err != nil {
 				b.Log.WithError(err).Error("Unable to send message with share URL.")
 			}
 		}
@@ -102,13 +112,24 @@ func (b *Bxmpp) Send(msg config.Message) (string, error) {
 		}
 	}
 
+	if b.GetString("WebhookURL") != "" {
+		b.Log.Debugf("Sending message using Webhook")
+		err := b.postSlackCompatibleWebhook(msg)
+		if err != nil {
+			b.Log.Errorf("Failed to send message using webhook: %s", err)
+			return "", err
+		}
+
+		return "", nil
+	}
+
+	// Post normal message.
 	var msgReplaceID string
 	msgID := xid.New().String()
 	if msg.ID != "" {
 		msgID = msg.ID
 		msgReplaceID = msg.ID
 	}
-	// Post normal message.
 	b.Log.Debugf("=> Sending message %#v", msg)
 	if _, err := b.xc.Send(xmpp.Chat{
 		Type:      "groupchat",
@@ -122,6 +143,25 @@ func (b *Bxmpp) Send(msg config.Message) (string, error) {
 	return msgID, nil
 }
 
+func (b *Bxmpp) postSlackCompatibleWebhook(msg config.Message) error {
+	type XMPPWebhook struct {
+		Username string `json:"username"`
+		Text     string `json:"text"`
+	}
+	webhookBody, err := json.Marshal(XMPPWebhook{
+		Username: msg.Username,
+		Text:     msg.Text,
+	})
+	if err != nil {
+		b.Log.Errorf("Failed to marshal webhook: %s", err)
+		return err
+	}
+
+	resp, err := http.Post(b.GetString("WebhookURL")+"/"+msg.Channel, "application/json", bytes.NewReader(webhookBody))
+	resp.Body.Close()
+	return err
+}
+
 func (b *Bxmpp) createXMPP() error {
 	if !strings.Contains(b.GetString("Jid"), "@") {
 		return fmt.Errorf("the Jid %s doesn't contain an @", b.GetString("Jid"))
@@ -378,6 +418,11 @@ func (b *Bxmpp) skipMessage(message xmpp.Chat) bool {
 		return true
 	}
 
+	// Ignore messages posted by our webhook
+	if b.GetString("WebhookURL") != "" && strings.Contains(message.ID, "webhookbot") {
+		return true
+	}
+
 	// skip delayed messages
 	return !message.Stamp.IsZero() && time.Since(message.Stamp).Minutes() > 5
 }
diff --git a/matterbridge.toml.sample b/matterbridge.toml.sample
index a92892b0..a398961a 100644
--- a/matterbridge.toml.sample
+++ b/matterbridge.toml.sample
@@ -310,6 +310,11 @@ StripNick=false
 #OPTIONAL (default false)
 ShowTopicChange=false
 
+#Enable sending messages using a webhook instead of regular MUC messages.
+#Only works with a prosody server using mod_slack_webhook. Does not support editing.
+#OPTIONAL (default "")
+WebhookURL="https://yourdomain/prosody/msg/someid"
+
 ###################################################################
 #mattermost section
 ###################################################################