From fd1fd560bc7dedd33a4e5232dfbcd9e0f7d88c92 Mon Sep 17 00:00:00 2001
From: bodqhrohro <bodqhrohro@gmail.com>
Date: Fri, 10 Jan 2020 15:02:25 +0200
Subject: [PATCH] Try to resume connection and resend a stanza on failure

---
 xmpp/component.go       |  4 ++--
 xmpp/gateway/gateway.go | 28 +++++++++++++++++++++++-----
 xmpp/handlers.go        | 16 ++++++++++++++--
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/xmpp/component.go b/xmpp/component.go
index d1c71ae..bbf0483 100644
--- a/xmpp/component.go
+++ b/xmpp/component.go
@@ -76,9 +76,9 @@ func heartbeat(component *xmpp.Component) {
 	for {
 		time.Sleep(60e9)
 		for key, presence := range gateway.Queue {
-			err = component.Send(presence)
+			err = gateway.ResumableSend(component, presence)
 			if err != nil {
-				gateway.LogBadPresence(err, presence)
+				gateway.LogBadPresence(presence)
 			} else {
 				delete(gateway.Queue, key)
 			}
diff --git a/xmpp/gateway/gateway.go b/xmpp/gateway/gateway.go
index 8629698..01269d0 100644
--- a/xmpp/gateway/gateway.go
+++ b/xmpp/gateway/gateway.go
@@ -2,6 +2,7 @@ package gateway
 
 import (
 	"encoding/xml"
+	"strings"
 
 	"dev.narayana.im/narayana/telegabber/xmpp/extensions"
 
@@ -55,12 +56,12 @@ func SendMessage(to string, from string, body string, component *xmpp.Component)
 		}
 	}
 
-	_ = component.Send(message)
+	_ = ResumableSend(component, message)
 }
 
 // LogBadPresence verbosely logs a presence
-func LogBadPresence(err error, presence *stanza.Presence) {
-	log.Errorf("Couldn't send presence: %v: %#v", err, presence)
+func LogBadPresence(presence *stanza.Presence) {
+	log.Errorf("Couldn't send presence: %#v", presence)
 }
 
 // SPFrom is a Telegram user id
@@ -167,9 +168,9 @@ func SendPresence(component *xmpp.Component, to string, args ...args.V) error {
 
 	immed := SPImmed.Get(args)
 	if immed {
-		err := component.Send(presence)
+		err := ResumableSend(component, presence)
 		if err != nil {
-			LogBadPresence(err, &presence)
+			LogBadPresence(&presence)
 			return err
 		}
 	} else {
@@ -178,3 +179,20 @@ func SendPresence(component *xmpp.Component, to string, args ...args.V) error {
 
 	return nil
 }
+
+// ResumableSend tries to resume the connection once and sends the packet again
+func ResumableSend(component *xmpp.Component, packet stanza.Packet) error {
+	err := component.Send(packet)
+	if err != nil && strings.HasPrefix(err.Error(), "cannot send packet") {
+		log.Warn("Packet send failed, trying to resume the connection...")
+		err = component.Connect()
+		if err == nil {
+			err = component.Send(packet)
+		}
+	}
+
+	if err != nil {
+		log.Error(err.Error())
+	}
+	return err
+}
diff --git a/xmpp/handlers.go b/xmpp/handlers.go
index 8778423..2e44411 100644
--- a/xmpp/handlers.go
+++ b/xmpp/handlers.go
@@ -126,7 +126,13 @@ func handleSubscription(s xmpp.Sender, p stanza.Presence) {
 		Type: "subscribed",
 	}}
 
-	_ = s.Send(reply)
+	component, ok := s.(*xmpp.Component)
+	if !ok {
+		log.Error("Not a component")
+		return
+	}
+
+	_ = gateway.ResumableSend(component, reply)
 }
 
 func handlePresence(s xmpp.Sender, p stanza.Presence) {
@@ -262,5 +268,11 @@ func handleGetVcardTempIq(s xmpp.Sender, iq stanza.IQ) {
 	}
 	log.Debugf("%#v", answer)
 
-	_ = s.Send(answer)
+	component, ok := s.(*xmpp.Component)
+	if !ok {
+		log.Error("Not a component")
+		return
+	}
+
+	_ = gateway.ResumableSend(component, answer)
 }