From ceaddee1dd2fb5a6f395fe25c5fc841708238027 Mon Sep 17 00:00:00 2001
From: Ivailo Monev <xakepa10@gmail.com>
Date: Fri, 10 May 2024 23:05:13 +0300
Subject: [PATCH] kutils: check if the avahi client pointer is null before
 using it in KDNSSD

should fix crashes due to internal avahi asserts in some cases (e.g. when
the daemon is not running)

Signed-off-by: Ivailo Monev <xakepa10@gmail.com>
---
 kutils/kdnssd/kdnssd.cpp | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/kutils/kdnssd/kdnssd.cpp b/kutils/kdnssd/kdnssd.cpp
index 1d5a1e21..02110600 100644
--- a/kutils/kdnssd/kdnssd.cpp
+++ b/kutils/kdnssd/kdnssd.cpp
@@ -149,6 +149,9 @@ KDNSSDPrivate::~KDNSSDPrivate()
 bool KDNSSDPrivate::publishService(const QByteArray &servicetype, const uint serviceport, const QString &servicename)
 {
 #if defined(HAVE_AVAHI)
+    if (!m_avahiclient) {
+        return false;
+    }
     if (m_avahigroup) {
         avahi_entry_group_reset(m_avahigroup);
     }
@@ -158,7 +161,6 @@ bool KDNSSDPrivate::publishService(const QByteArray &servicetype, const uint ser
         return false;
     }
     const QByteArray servicenamebytes = servicename.toUtf8();
-    // qDebug() << Q_FUNC_INFO << servicenamebytes << servicetype;
     int avahiresult = avahi_entry_group_add_service(
         m_avahigroup,
         AVAHI_IF_UNSPEC, s_avahiproto,
@@ -201,8 +203,9 @@ bool KDNSSDPrivate::unpublishService()
 bool KDNSSDPrivate::startBrowse(const QByteArray &servicetype)
 {
 #if defined(HAVE_AVAHI)
-    // qDebug() << Q_FUNC_INFO << servicetype;
-
+    if (!m_avahiclient) {
+        return false;
+    }
     m_pollcounter = 0;
     QList<QByteArray> servicetypes;
     if (servicetype.isEmpty()) {
@@ -220,7 +223,6 @@ bool KDNSSDPrivate::startBrowse(const QByteArray &servicetype)
         m_pollcounter++;
         m_servicetypes.clear();
         while (m_pollcounter) {
-            // qDebug() << Q_FUNC_INFO << m_pollcounter;
             avahi_simple_poll_iterate(m_avahipoll, 0);
         }
 
@@ -247,7 +249,6 @@ bool KDNSSDPrivate::startBrowse(const QByteArray &servicetype)
 
         m_pollcounter++;
         while (m_pollcounter) {
-            // qDebug() << Q_FUNC_INFO << m_pollcounter;
             avahi_simple_poll_iterate(m_avahipoll, 0);
         }
 
@@ -277,8 +278,6 @@ QString KDNSSDPrivate::errorString() const
 #if defined(HAVE_AVAHI)
 void KDNSSDPrivate::groupCallback(AvahiEntryGroup *avahigroup, AvahiEntryGroupState avahistate, void *userdata)
 {
-    // qDebug() << Q_FUNC_INFO << avahigroup << avahistate << userdata;
-
     if (avahistate == AVAHI_ENTRY_GROUP_FAILURE) {
         KDNSSDPrivate *kdnssdprivate = static_cast<KDNSSDPrivate*>(userdata);
         kdnssdprivate->m_errorstring = getAvahiClientError(avahi_entry_group_get_client(avahigroup));
@@ -287,8 +286,6 @@ void KDNSSDPrivate::groupCallback(AvahiEntryGroup *avahigroup, AvahiEntryGroupSt
 
 void KDNSSDPrivate::clientCallback(AvahiClient *avahiclient, AvahiClientState avahistate, void *userdata)
 {
-    // qDebug() << Q_FUNC_INFO << avahistate << userdata;
-
     if (avahistate == AVAHI_CLIENT_FAILURE) {
         KDNSSDPrivate *kdnssdprivate = static_cast<KDNSSDPrivate*>(userdata);
         kdnssdprivate->m_errorstring = getAvahiClientError(avahiclient);
@@ -303,8 +300,6 @@ void KDNSSDPrivate::browseCallback(AvahiServiceBrowser *avahibrowser, AvahiIfInd
 {
     Q_UNUSED(avahiflags);
 
-    // qDebug() << Q_FUNC_INFO << avahievent << avahiname << avahitype << avahidomain << userdata;
-
     KDNSSDPrivate *kdnssdprivate = static_cast<KDNSSDPrivate*>(userdata);
     AvahiClient *avahiclient = avahi_service_browser_get_client(avahibrowser);
     switch (avahievent) {
@@ -357,8 +352,6 @@ void KDNSSDPrivate::resolveCallback(AvahiServiceResolver *avahiresolver, AvahiIf
     Q_UNUSED(avahiflags);
     Q_UNUSED(avahiflags);
 
-    // qDebug() << Q_FUNC_INFO << avahievent << avahiname << avahitype << avahidomain << userdata;
-
     KDNSSDPrivate *kdnssdprivate = static_cast<KDNSSDPrivate*>(userdata);
     switch (avahievent) {
         case AVAHI_RESOLVER_FOUND: {
@@ -429,8 +422,6 @@ void KDNSSDPrivate::serviceCallback(AvahiServiceTypeBrowser *avahiservice,
     Q_UNUSED(avahiprotocol);
     Q_UNUSED(avahiflags);
 
-    // qDebug() << Q_FUNC_INFO << avahievent << avahitype << avahidomain << userdata;
-
     KDNSSDPrivate *kdnssdprivate = static_cast<KDNSSDPrivate*>(userdata);
     AvahiClient *avahiclient = avahi_service_type_browser_get_client(avahiservice);
     switch (avahievent) {