From 57ce26c0b465dce332a59c9fabb05f737ff4241d Mon Sep 17 00:00:00 2001 From: Andrei Vagin Date: Wed, 18 Dec 2019 18:22:50 -0800 Subject: net/tcp: allow to call listen without bind When listen(2) is called on an unbound socket, the socket is automatically bound to a random free port with the local address set to INADDR_ANY. PiperOrigin-RevId: 286305906 --- pkg/tcpip/transport/tcp/endpoint.go | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'pkg') diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go index dd8b47cbe..fe629aa40 100644 --- a/pkg/tcpip/transport/tcp/endpoint.go +++ b/pkg/tcpip/transport/tcp/endpoint.go @@ -1974,6 +1974,15 @@ func (e *endpoint) listen(backlog int) *tcpip.Error { return nil } + if e.state == StateInitial { + // The listen is called on an unbound socket, the socket is + // automatically bound to a random free port with the local + // address set to INADDR_ANY. + if err := e.bindLocked(tcpip.FullAddress{}); err != nil { + return err + } + } + // Endpoint must be bound before it can transition to listen mode. if e.state != StateBound { e.stats.ReadErrors.InvalidEndpointState.Increment() @@ -2033,6 +2042,10 @@ func (e *endpoint) Bind(addr tcpip.FullAddress) (err *tcpip.Error) { e.mu.Lock() defer e.mu.Unlock() + return e.bindLocked(addr) +} + +func (e *endpoint) bindLocked(addr tcpip.FullAddress) (err *tcpip.Error) { // Don't allow binding once endpoint is not in the initial state // anymore. This is because once the endpoint goes into a connected or // listen state, it is already bound. -- cgit v1.2.3