1 files changed, 58 insertions, 0 deletions

diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index c021c67ac..a35d6562e 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -57,6 +57,9 @@ type Error struct {
 
 // String implements fmt.Stringer.String.
 func (e *Error) String() string {
+	if e == nil {
+		return "<nil>"
+	}
 	return e.msg
 }
 
@@ -495,6 +498,10 @@ type ReuseAddressOption int
 // to be bound to an identical socket address.
 type ReusePortOption int
 
+// BindToDeviceOption is used by SetSockOpt/GetSockOpt to specify that sockets
+// should bind only on a specific NIC.
+type BindToDeviceOption string
+
 // QuickAckOption is stubbed out in SetSockOpt/GetSockOpt.
 type QuickAckOption int
 
@@ -546,6 +553,12 @@ type ModerateReceiveBufferOption bool
 // Maximum Segment Size(MSS) value as specified using the TCP_MAXSEG option.
 type MaxSegOption int
 
+// TTLOption is used by SetSockOpt/GetSockOpt to control the default TTL/hop
+// limit value for unicast messages. The default is protocol specific.
+//
+// A zero value indicates the default.
+type TTLOption uint8
+
 // MulticastTTLOption is used by SetSockOpt/GetSockOpt to control the default
 // TTL value for multicast messages. The default is 1.
 type MulticastTTLOption uint8
@@ -587,6 +600,10 @@ type OutOfBandInlineOption int
 // datagram sockets are allowed to send packets to a broadcast address.
 type BroadcastOption int
 
+// DefaultTTLOption is used by stack.(*Stack).NetworkProtocolOption to specify
+// a default TTL.
+type DefaultTTLOption uint8
+
 // Route is a row in the routing table. It specifies through which NIC (and
 // gateway) sets of packets should be routed. A row is considered viable if the
 // masked target address matches the destination address in the row.
@@ -1091,6 +1108,47 @@ func (a AddressWithPrefix) String() string {
 	return fmt.Sprintf("%s/%d", a.Address, a.PrefixLen)
 }
 
+// Subnet converts the address and prefix into a Subnet value and returns it.
+func (a AddressWithPrefix) Subnet() Subnet {
+	addrLen := len(a.Address)
+	if a.PrefixLen <= 0 {
+		return Subnet{
+			address: Address(strings.Repeat("\x00", addrLen)),
+			mask:    AddressMask(strings.Repeat("\x00", addrLen)),
+		}
+	}
+	if a.PrefixLen >= addrLen*8 {
+		return Subnet{
+			address: a.Address,
+			mask:    AddressMask(strings.Repeat("\xff", addrLen)),
+		}
+	}
+
+	sa := make([]byte, addrLen)
+	sm := make([]byte, addrLen)
+	n := uint(a.PrefixLen)
+	for i := 0; i < addrLen; i++ {
+		if n >= 8 {
+			sa[i] = a.Address[i]
+			sm[i] = 0xff
+			n -= 8
+			continue
+		}
+		sm[i] = ^byte(0xff >> n)
+		sa[i] = a.Address[i] & sm[i]
+		n = 0
+	}
+
+	// For extra caution, call NewSubnet rather than directly creating the Subnet
+	// value. If that fails it indicates a serious bug in this code, so panic is
+	// in order.
+	s, err := NewSubnet(Address(sa), AddressMask(sm))
+	if err != nil {
+		panic("invalid subnet: " + err.Error())
+	}
+	return s
+}
+
 // ProtocolAddress is an address and the network protocol it is associated
 // with.
 type ProtocolAddress struct {