QNetworkInterface/Linux: fix support for P-t-P tunnels

The kernel stores the local address in IFA_LOCAL and the peer's address
in IFA_ADDRESS. My testing with loopback, Ethernet, WiFi, OpenVPN TAP
and TUN and Openconnect shows IFA_LOCAL is always passed and always
correct, so we could have used just that, but let's leave the use of
IFA_ADDRESS because that's also what all libcs' getifaddrs() do.

[ChangeLog][QtNetwork][QNetworkInterface] Fixed a regression in
reporting the local address of a point-to-point tunnel network
interface.

Task-number: QTBUG-67226
Change-Id: I04a43ee94975482f9e32fffd151eb393d1775580
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 8 insertions, 1 deletions

diff --git a/src/network/kernel/qnetworkinterface_linux.cpp b/src/network/kernel/qnetworkinterface_linux.cpp
index 01b2811070..5dc62bf7bb 100644
--- a/src/network/kernel/qnetworkinterface_linux.cpp
+++ b/src/network/kernel/qnetworkinterface_linux.cpp
@@ -382,7 +382,14 @@ static void getAddresses(int sock, char *buf, QList<QNetworkInterfacePrivate *>
             auto payloadPtr = reinterpret_cast<uchar *>(RTA_DATA(rta));
 
             switch (rta->rta_type) {
-            case IFA_ADDRESS:           // address
+            case IFA_ADDRESS:
+                // Local address (all interfaces except for point-to-point)
+                if (entry.ip().isNull())
+                    entry.setIp(makeAddress(payloadPtr, payloadLen));
+                break;
+
+            case IFA_LOCAL:
+                // Override the local address (point-to-point interfaces)
                 entry.setIp(makeAddress(payloadPtr, payloadLen));
                 break;