Why does QHostAddress::protocol() always return QAbstractSocket::IPv6Protocol

yvbbrjdr · wrote on 4 Sept 2016, 08:46

When I establish IPv4 connection between a QTcpSocket and a QTcpServer, I find out that the socket.peerAddress().toString() returns a IPv6 version of IPv4 address, which is like ::ffff:192.168.1.100. And then I check the socket.peerAddress().protocol() and it returns QAbstractSocket::IPv6Protocol. Why does it return an IPv6 when I am using IPv4?

yvbbrjdr · wrote on 4 Sept 2016, 11:23

I found that it is the same in all platforms, including Windows, Linux, and macOS.

SGaist · 5 Sept 2016, 16:04

Hi,

AFAICS, your system is using a IPV4 mapped IPV6. So technically there's nothing wrong going on from a Qt point of view. The IPV4/IPV6 handling is done outside of Qt's scope and you get accurate information.

yvbbrjdr · S SGaist 4 Sept 2016, 20:29

@SGaist So I am trying to use the function QHostAddress::toIPv4Address(bool *ok) and check the "ok" to see if the IP address is a IPv4. Is that OK?

SGaist · wrote on 5 Sept 2016, 20:34

AFAIK, it should be yes.

alex_la · wrote on 14 Nov 2022, 22:33

It's a bug in Qt. Appears everytime. Even if disable IPv6 stack.

ChrisW67 · wrote on 16 Nov 2022, 08:10

This post is deleted!