Improve type safety for transport protocol options

The existing implementation for TransportProtocol.{Set}Option take
arguments of an empty interface type which all types (implicitly)
implement; any type may be passed to the functions.

This change introduces marker interfaces for transport protocol options
that may be set or queried which transport protocol option types
implement to ensure that invalid types are caught at compile time.
Different interfaces are used to allow the compiler to enforce read-only
or set-only socket options.

RELNOTES: n/a
PiperOrigin-RevId: 330559811

1 files changed, 122 insertions, 5 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 8ba615521..5e34e27ba 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -864,12 +864,93 @@ func (*DefaultTTLOption) isGettableNetworkProtocolOption() {}
 
 func (*DefaultTTLOption) isSettableNetworkProtocolOption() {}
 
-// AvailableCongestionControlOption is used to query the supported congestion
-// control algorithms.
-type AvailableCongestionControlOption string
+// GettableTransportProtocolOption is a marker interface for transport protocol
+// options that may be queried.
+type GettableTransportProtocolOption interface {
+	isGettableTransportProtocolOption()
+}
+
+// SettableTransportProtocolOption is a marker interface for transport protocol
+// options that may be set.
+type SettableTransportProtocolOption interface {
+	isSettableTransportProtocolOption()
+}
+
+// TCPSACKEnabled the SACK option for TCP.
+//
+// See: https://tools.ietf.org/html/rfc2018.
+type TCPSACKEnabled bool
+
+func (*TCPSACKEnabled) isGettableTransportProtocolOption() {}
+
+func (*TCPSACKEnabled) isSettableTransportProtocolOption() {}
+
+// TCPRecovery is the loss deteoction algorithm used by TCP.
+type TCPRecovery int32
+
+func (*TCPRecovery) isGettableTransportProtocolOption() {}
+
+func (*TCPRecovery) isSettableTransportProtocolOption() {}
+
+const (
+	// TCPRACKLossDetection indicates RACK is used for loss detection and
+	// recovery.
+	TCPRACKLossDetection TCPRecovery = 1 << iota
+
+	// TCPRACKStaticReoWnd indicates the reordering window should not be
+	// adjusted when DSACK is received.
+	TCPRACKStaticReoWnd
+
+	// TCPRACKNoDupTh indicates RACK should not consider the classic three
+	// duplicate acknowledgements rule to mark the segments as lost. This
+	// is used when reordering is not detected.
+	TCPRACKNoDupTh
+)
+
+// TCPDelayEnabled enables/disables Nagle's algorithm in TCP.
+type TCPDelayEnabled bool
+
+func (*TCPDelayEnabled) isGettableTransportProtocolOption() {}
+
+func (*TCPDelayEnabled) isSettableTransportProtocolOption() {}
+
+// TCPSendBufferSizeRangeOption is the send buffer size range for TCP.
+type TCPSendBufferSizeRangeOption struct {
+	Min     int
+	Default int
+	Max     int
+}
+
+func (*TCPSendBufferSizeRangeOption) isGettableTransportProtocolOption() {}
+
+func (*TCPSendBufferSizeRangeOption) isSettableTransportProtocolOption() {}
+
+// TCPReceiveBufferSizeRangeOption is the receive buffer size range for TCP.
+type TCPReceiveBufferSizeRangeOption struct {
+	Min     int
+	Default int
+	Max     int
+}
+
+func (*TCPReceiveBufferSizeRangeOption) isGettableTransportProtocolOption() {}
+
+func (*TCPReceiveBufferSizeRangeOption) isSettableTransportProtocolOption() {}
+
+// TCPAvailableCongestionControlOption is the supported congestion control
+// algorithms for TCP
+type TCPAvailableCongestionControlOption string
+
+func (*TCPAvailableCongestionControlOption) isGettableTransportProtocolOption() {}
+
+func (*TCPAvailableCongestionControlOption) isSettableTransportProtocolOption() {}
+
+// TCPModerateReceiveBufferOption enables/disables receive buffer moderation
+// for TCP.
+type TCPModerateReceiveBufferOption bool
 
-// ModerateReceiveBufferOption is used by buffer moderation.
-type ModerateReceiveBufferOption bool
+func (*TCPModerateReceiveBufferOption) isGettableTransportProtocolOption() {}
+
+func (*TCPModerateReceiveBufferOption) isSettableTransportProtocolOption() {}
 
 // GettableSocketOption is a marker interface for socket options that may be
 // queried.
@@ -935,6 +1016,10 @@ func (*CongestionControlOption) isGettableSocketOption() {}
 
 func (*CongestionControlOption) isSettableSocketOption() {}
 
+func (*CongestionControlOption) isGettableTransportProtocolOption() {}
+
+func (*CongestionControlOption) isSettableTransportProtocolOption() {}
+
 // TCPLingerTimeoutOption is used by SetSockOpt/GetSockOpt to set/get the
 // maximum duration for which a socket lingers in the TCP_FIN_WAIT_2 state
 // before being marked closed.
@@ -944,6 +1029,10 @@ func (*TCPLingerTimeoutOption) isGettableSocketOption() {}
 
 func (*TCPLingerTimeoutOption) isSettableSocketOption() {}
 
+func (*TCPLingerTimeoutOption) isGettableTransportProtocolOption() {}
+
+func (*TCPLingerTimeoutOption) isSettableTransportProtocolOption() {}
+
 // TCPTimeWaitTimeoutOption is used by SetSockOpt/GetSockOpt to set/get the
 // maximum duration for which a socket lingers in the TIME_WAIT state
 // before being marked closed.
@@ -953,6 +1042,10 @@ func (*TCPTimeWaitTimeoutOption) isGettableSocketOption() {}
 
 func (*TCPTimeWaitTimeoutOption) isSettableSocketOption() {}
 
+func (*TCPTimeWaitTimeoutOption) isGettableTransportProtocolOption() {}
+
+func (*TCPTimeWaitTimeoutOption) isSettableTransportProtocolOption() {}
+
 // TCPDeferAcceptOption is used by SetSockOpt/GetSockOpt to allow a
 // accept to return a completed connection only when there is data to be
 // read. This usually means the listening socket will drop the final ACK
@@ -971,6 +1064,10 @@ func (*TCPMinRTOOption) isGettableSocketOption() {}
 
 func (*TCPMinRTOOption) isSettableSocketOption() {}
 
+func (*TCPMinRTOOption) isGettableTransportProtocolOption() {}
+
+func (*TCPMinRTOOption) isSettableTransportProtocolOption() {}
+
 // TCPMaxRTOOption is use by SetSockOpt/GetSockOpt to allow overriding
 // default MaxRTO used by the Stack.
 type TCPMaxRTOOption time.Duration
@@ -979,6 +1076,10 @@ func (*TCPMaxRTOOption) isGettableSocketOption() {}
 
 func (*TCPMaxRTOOption) isSettableSocketOption() {}
 
+func (*TCPMaxRTOOption) isGettableTransportProtocolOption() {}
+
+func (*TCPMaxRTOOption) isSettableTransportProtocolOption() {}
+
 // TCPMaxRetriesOption is used by SetSockOpt/GetSockOpt to set/get the
 // maximum number of retransmits after which we time out the connection.
 type TCPMaxRetriesOption uint64
@@ -987,6 +1088,10 @@ func (*TCPMaxRetriesOption) isGettableSocketOption() {}
 
 func (*TCPMaxRetriesOption) isSettableSocketOption() {}
 
+func (*TCPMaxRetriesOption) isGettableTransportProtocolOption() {}
+
+func (*TCPMaxRetriesOption) isSettableTransportProtocolOption() {}
+
 // TCPSynRcvdCountThresholdOption is used by SetSockOpt/GetSockOpt to specify
 // the number of endpoints that can be in SYN-RCVD state before the stack
 // switches to using SYN cookies.
@@ -996,6 +1101,10 @@ func (*TCPSynRcvdCountThresholdOption) isGettableSocketOption() {}
 
 func (*TCPSynRcvdCountThresholdOption) isSettableSocketOption() {}
 
+func (*TCPSynRcvdCountThresholdOption) isGettableTransportProtocolOption() {}
+
+func (*TCPSynRcvdCountThresholdOption) isSettableTransportProtocolOption() {}
+
 // TCPSynRetriesOption is used by SetSockOpt/GetSockOpt to specify stack-wide
 // default for number of times SYN is retransmitted before aborting a connect.
 type TCPSynRetriesOption uint8
@@ -1004,6 +1113,10 @@ func (*TCPSynRetriesOption) isGettableSocketOption() {}
 
 func (*TCPSynRetriesOption) isSettableSocketOption() {}
 
+func (*TCPSynRetriesOption) isGettableTransportProtocolOption() {}
+
+func (*TCPSynRetriesOption) isSettableTransportProtocolOption() {}
+
 // MulticastInterfaceOption is used by SetSockOpt/GetSockOpt to specify a
 // default interface for multicast.
 type MulticastInterfaceOption struct {
@@ -1062,6 +1175,10 @@ func (*TCPTimeWaitReuseOption) isGettableSocketOption() {}
 
 func (*TCPTimeWaitReuseOption) isSettableSocketOption() {}
 
+func (*TCPTimeWaitReuseOption) isGettableTransportProtocolOption() {}
+
+func (*TCPTimeWaitReuseOption) isSettableTransportProtocolOption() {}
+
 const (
 	// TCPTimeWaitReuseDisabled indicates reuse of port bound by endponts in TIME-WAIT cannot
 	// be reused for new connections.