Add UDP SO_REUSEADDR support to the port manager.

Next steps include adding support to the transport demuxer and the UDP endpoint.

PiperOrigin-RevId: 284652151

2 files changed, 18 insertions, 8 deletions

diff --git a/pkg/tcpip/transport/tcp/BUILD b/pkg/tcpip/transport/tcp/BUILD
index dd1728f9c..455a1c098 100644
--- a/pkg/tcpip/transport/tcp/BUILD
+++ b/pkg/tcpip/transport/tcp/BUILD
@@ -52,6 +52,7 @@ go_library(
         "//pkg/tcpip/hash/jenkins",
         "//pkg/tcpip/header",
         "//pkg/tcpip/iptables",
+        "//pkg/tcpip/ports",
         "//pkg/tcpip/seqnum",
         "//pkg/tcpip/stack",
         "//pkg/tcpip/transport/raw",
diff --git a/pkg/tcpip/transport/tcp/endpoint.go b/pkg/tcpip/transport/tcp/endpoint.go
index 9d4a87e30..4861ab513 100644
--- a/pkg/tcpip/transport/tcp/endpoint.go
+++ b/pkg/tcpip/transport/tcp/endpoint.go
@@ -30,6 +30,7 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/hash/jenkins"
 	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/iptables"
+	"gvisor.dev/gvisor/pkg/tcpip/ports"
 	"gvisor.dev/gvisor/pkg/tcpip/seqnum"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tmutex"
@@ -343,6 +344,7 @@ type endpoint struct {
 	// Values used to reserve a port or register a transport endpoint
 	// (which ever happens first).
 	boundBindToDevice tcpip.NICID
+	boundPortFlags    ports.Flags
 
 	// effectiveNetProtos contains the network protocols actually in use. In
 	// most cases it will only contain "netProto", but in cases like IPv6
@@ -737,9 +739,10 @@ func (e *endpoint) Close() {
 			e.isRegistered = false
 		}
 
-		e.stack.ReleasePort(e.effectiveNetProtos, ProtocolNumber, e.ID.LocalAddress, e.ID.LocalPort, e.boundBindToDevice)
+		e.stack.ReleasePort(e.effectiveNetProtos, ProtocolNumber, e.ID.LocalAddress, e.ID.LocalPort, e.boundPortFlags, e.boundBindToDevice)
 		e.isPortReserved = false
 		e.boundBindToDevice = 0
+		e.boundPortFlags = ports.Flags{}
 	}
 
 	// Mark endpoint as closed.
@@ -800,10 +803,11 @@ func (e *endpoint) cleanupLocked() {
 	}
 
 	if e.isPortReserved {
-		e.stack.ReleasePort(e.effectiveNetProtos, ProtocolNumber, e.ID.LocalAddress, e.ID.LocalPort, e.boundBindToDevice)
+		e.stack.ReleasePort(e.effectiveNetProtos, ProtocolNumber, e.ID.LocalAddress, e.ID.LocalPort, e.boundPortFlags, e.boundBindToDevice)
 		e.isPortReserved = false
 	}
 	e.boundBindToDevice = 0
+	e.boundPortFlags = ports.Flags{}
 
 	e.route.Release()
 	e.stack.CompleteTransportEndpointCleanup(e)
@@ -1775,7 +1779,7 @@ func (e *endpoint) connect(addr tcpip.FullAddress, handshake bool, run bool) *tc
 			}
 			// reusePort is false below because connect cannot reuse a port even if
 			// reusePort was set.
-			if !e.stack.IsPortAvailable(netProtos, ProtocolNumber, e.ID.LocalAddress, p, false /* reusePort */, e.bindToDevice) {
+			if !e.stack.IsPortAvailable(netProtos, ProtocolNumber, e.ID.LocalAddress, p, ports.Flags{LoadBalanced: false}, e.bindToDevice) {
 				return false, nil
 			}
 
@@ -1802,7 +1806,7 @@ func (e *endpoint) connect(addr tcpip.FullAddress, handshake bool, run bool) *tc
 	// before Connect: in such a case we don't want to hold on to
 	// reservations anymore.
 	if e.isPortReserved {
-		e.stack.ReleasePort(e.effectiveNetProtos, ProtocolNumber, origID.LocalAddress, origID.LocalPort, e.boundBindToDevice)
+		e.stack.ReleasePort(e.effectiveNetProtos, ProtocolNumber, origID.LocalAddress, origID.LocalPort, e.boundPortFlags, e.boundBindToDevice)
 		e.isPortReserved = false
 	}
 
@@ -2034,28 +2038,33 @@ func (e *endpoint) Bind(addr tcpip.FullAddress) (err *tcpip.Error) {
 		}
 	}
 
-	port, err := e.stack.ReservePort(netProtos, ProtocolNumber, addr.Addr, addr.Port, e.reusePort, e.bindToDevice)
+	flags := ports.Flags{
+		LoadBalanced: e.reusePort,
+	}
+	port, err := e.stack.ReservePort(netProtos, ProtocolNumber, addr.Addr, addr.Port, flags, e.bindToDevice)
 	if err != nil {
 		return err
 	}
 
 	e.boundBindToDevice = e.bindToDevice
+	e.boundPortFlags = flags
 	e.isPortReserved = true
 	e.effectiveNetProtos = netProtos
 	e.ID.LocalPort = port
 
 	// Any failures beyond this point must remove the port registration.
-	defer func(bindToDevice tcpip.NICID) {
+	defer func(portFlags ports.Flags, bindToDevice tcpip.NICID) {
 		if err != nil {
-			e.stack.ReleasePort(netProtos, ProtocolNumber, addr.Addr, port, bindToDevice)
+			e.stack.ReleasePort(netProtos, ProtocolNumber, addr.Addr, port, portFlags, bindToDevice)
 			e.isPortReserved = false
 			e.effectiveNetProtos = nil
 			e.ID.LocalPort = 0
 			e.ID.LocalAddress = ""
 			e.boundNICID = 0
 			e.boundBindToDevice = 0
+			e.boundPortFlags = ports.Flags{}
 		}
-	}(e.boundBindToDevice)
+	}(e.boundPortFlags, e.boundBindToDevice)
 
 	// If an address is specified, we must ensure that it's one of our
 	// local addresses.