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-rw-r--r--pkg/tcpip/network/ipv4/ipv4.go168
-rw-r--r--pkg/tcpip/network/ipv4/ipv4_test.go78
2 files changed, 105 insertions, 141 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index a2be64fb8..79c939129 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -190,99 +190,26 @@ func (e *endpoint) NetworkProtocolNumber() tcpip.NetworkProtocolNumber {
return e.protocol.Number()
}
-// writePacketFragments calls e.linkEP.WritePacket with each packet fragment to
-// write. It assumes that the IP header is already present in pkt.NetworkHeader.
-// pkt.TransportHeader may be set. mtu includes the IP header and options. This
-// does not support the DontFragment IP flag.
-func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int, pkt *stack.PacketBuffer) *tcpip.Error {
- // This packet is too big, it needs to be fragmented.
- ip := header.IPv4(pkt.NetworkHeader().View())
- flags := ip.Flags()
-
- // Update mtu to take into account the header, which will exist in all
- // fragments anyway.
- innerMTU := mtu - int(ip.HeaderLength())
-
- // Round the MTU down to align to 8 bytes. Then calculate the number of
- // fragments. Calculate fragment sizes as in RFC791.
- innerMTU &^= 7
- n := (int(ip.PayloadLength()) + innerMTU - 1) / innerMTU
-
- outerMTU := innerMTU + int(ip.HeaderLength())
- offset := ip.FragmentOffset()
-
- // Keep the length reserved for link-layer, we need to create fragments with
- // the same reserved length.
- reservedForLink := pkt.AvailableHeaderBytes()
-
- // Destroy the packet, pull all payloads out for fragmentation.
- transHeader, data := pkt.TransportHeader().View(), pkt.Data
-
- // Where possible, the first fragment that is sent has the same
- // number of bytes reserved for header as the input packet. The link-layer
- // endpoint may depend on this for looking at, eg, L4 headers.
- transFitsFirst := len(transHeader) <= innerMTU
-
- for i := 0; i < n; i++ {
- reserve := reservedForLink + int(ip.HeaderLength())
- if i == 0 && transFitsFirst {
- // Reserve for transport header if it's going to be put in the first
- // fragment.
- reserve += len(transHeader)
- }
- fragPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
- ReserveHeaderBytes: reserve,
- })
- fragPkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
-
- // Copy data for the fragment.
- avail := innerMTU
-
- if n := len(transHeader); n > 0 {
- if n > avail {
- n = avail
- }
- if i == 0 && transFitsFirst {
- copy(fragPkt.TransportHeader().Push(n), transHeader)
- } else {
- fragPkt.Data.AppendView(transHeader[:n:n])
- }
- transHeader = transHeader[n:]
- avail -= n
- }
-
- if avail > 0 {
- n := data.Size()
- if n > avail {
- n = avail
- }
- data.ReadToVV(&fragPkt.Data, n)
- avail -= n
- }
-
- copied := uint16(innerMTU - avail)
-
- // Set lengths in header and calculate checksum.
- h := header.IPv4(fragPkt.NetworkHeader().Push(len(ip)))
- copy(h, ip)
- if i != n-1 {
- h.SetTotalLength(uint16(outerMTU))
- h.SetFlagsFragmentOffset(flags|header.IPv4FlagMoreFragments, offset)
- } else {
- h.SetTotalLength(uint16(h.HeaderLength()) + copied)
- h.SetFlagsFragmentOffset(flags, offset)
- }
- h.SetChecksum(0)
- h.SetChecksum(^h.CalculateChecksum())
- offset += copied
-
- // Send out the fragment.
+// writePacketFragments fragments pkt and writes the results on the link
+// endpoint. The IP header must already present in the original packet. The mtu
+// is the maximum size of the packets.
+func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu uint32, pkt *stack.PacketBuffer) *tcpip.Error {
+ networkHeader := header.IPv4(pkt.NetworkHeader().View())
+ fragMTU := int(calculateFragmentInnerMTU(mtu, pkt))
+ pf := fragmentation.MakePacketFragmenter(pkt, fragMTU, pkt.AvailableHeaderBytes()+len(networkHeader))
+
+ for {
+ fragPkt, more := buildNextFragment(&pf, networkHeader)
if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, fragPkt); err != nil {
- r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(n - i))
+ r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(pf.RemainingFragmentCount() + 1))
return err
}
r.Stats().IP.PacketsSent.Increment()
+ if !more {
+ break
+ }
}
+
return nil
}
@@ -304,7 +231,7 @@ func (e *endpoint) addIPHeader(r *stack.Route, pkt *stack.PacketBuffer, params s
DstAddr: r.RemoteAddress,
})
ip.SetChecksum(^ip.CalculateChecksum())
- pkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
+ pkt.NetworkProtocolNumber = ProtocolNumber
}
// WritePacket writes a packet to the given destination address and protocol.
@@ -330,7 +257,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
// short circuits broadcasts before they are sent out to other hosts.
if pkt.NatDone {
netHeader := header.IPv4(pkt.NetworkHeader().View())
- ep, err := e.protocol.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress())
+ ep, err := e.protocol.stack.FindNetworkEndpoint(ProtocolNumber, netHeader.DestinationAddress())
if err == nil {
route := r.ReverseRoute(netHeader.SourceAddress(), netHeader.DestinationAddress())
ep.HandlePacket(&route, pkt)
@@ -347,7 +274,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
return nil
}
if pkt.Size() > int(e.linkEP.MTU()) && (gso == nil || gso.Type == stack.GSONone) {
- return e.writePacketFragments(r, gso, int(e.linkEP.MTU()), pkt)
+ return e.writePacketFragments(r, gso, e.linkEP.MTU(), pkt)
}
if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, pkt); err != nil {
r.Stats().IP.OutgoingPacketErrors.Increment()
@@ -397,7 +324,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
}
if _, ok := natPkts[pkt]; ok {
netHeader := header.IPv4(pkt.NetworkHeader().View())
- if ep, err := e.protocol.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress()); err == nil {
+ if ep, err := e.protocol.stack.FindNetworkEndpoint(ProtocolNumber, netHeader.DestinationAddress()); err == nil {
src := netHeader.SourceAddress()
dst := netHeader.DestinationAddress()
route := r.ReverseRoute(src, dst)
@@ -809,14 +736,36 @@ func calculateMTU(mtu uint32) uint32 {
return mtu - header.IPv4MinimumSize
}
+// calculateFragmentInnerMTU calculates the maximum number of bytes of
+// fragmentable data a fragment can have, based on the link layer mtu and pkt's
+// network header size.
+func calculateFragmentInnerMTU(mtu uint32, pkt *stack.PacketBuffer) uint32 {
+ if mtu > MaxTotalSize {
+ mtu = MaxTotalSize
+ }
+ mtu -= uint32(pkt.NetworkHeader().View().Size())
+ // Round the MTU down to align to 8 bytes.
+ mtu &^= 7
+ return mtu
+}
+
+// addressToUint32 translates an IPv4 address into its little endian uint32
+// representation.
+//
+// This function does the same thing as binary.LittleEndian.Uint32 but operates
+// on a tcpip.Address (a string) without the need to convert it to a byte slice,
+// which would cause an allocation.
+func addressToUint32(addr tcpip.Address) uint32 {
+ _ = addr[3] // bounds check hint to compiler
+ return uint32(addr[0]) | uint32(addr[1])<<8 | uint32(addr[2])<<16 | uint32(addr[3])<<24
+}
+
// hashRoute calculates a hash value for the given route. It uses the source &
-// destination address, the transport protocol number, and a random initial
-// value (generated once on initialization) to generate the hash.
+// destination address, the transport protocol number and a 32-bit number to
+// generate the hash.
func hashRoute(r *stack.Route, protocol tcpip.TransportProtocolNumber, hashIV uint32) uint32 {
- t := r.LocalAddress
- a := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24
- t = r.RemoteAddress
- b := uint32(t[0]) | uint32(t[1])<<8 | uint32(t[2])<<16 | uint32(t[3])<<24
+ a := addressToUint32(r.LocalAddress)
+ b := addressToUint32(r.RemoteAddress)
return hash.Hash3Words(a, b, uint32(protocol), hashIV)
}
@@ -839,3 +788,26 @@ func NewProtocol(s *stack.Stack) stack.NetworkProtocol {
fragmentation: fragmentation.NewFragmentation(fragmentblockSize, fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout, s.Clock()),
}
}
+
+func buildNextFragment(pf *fragmentation.PacketFragmenter, originalIPHeader header.IPv4) (*stack.PacketBuffer, bool) {
+ fragPkt, offset, copied, more := pf.BuildNextFragment()
+ fragPkt.NetworkProtocolNumber = ProtocolNumber
+
+ originalIPHeaderLength := len(originalIPHeader)
+ nextFragIPHeader := header.IPv4(fragPkt.NetworkHeader().Push(originalIPHeaderLength))
+
+ if copied := copy(nextFragIPHeader, originalIPHeader); copied != len(originalIPHeader) {
+ panic(fmt.Sprintf("wrong number of bytes copied into fragmentIPHeaders: got = %d, want = %d", copied, originalIPHeaderLength))
+ }
+
+ flags := originalIPHeader.Flags()
+ if more {
+ flags |= header.IPv4FlagMoreFragments
+ }
+ nextFragIPHeader.SetFlagsFragmentOffset(flags, uint16(offset))
+ nextFragIPHeader.SetTotalLength(uint16(nextFragIPHeader.HeaderLength()) + uint16(copied))
+ nextFragIPHeader.SetChecksum(0)
+ nextFragIPHeader.SetChecksum(^nextFragIPHeader.CalculateChecksum())
+
+ return fragPkt, more
+}
diff --git a/pkg/tcpip/network/ipv4/ipv4_test.go b/pkg/tcpip/network/ipv4/ipv4_test.go
index 712fbb861..f250a3cde 100644
--- a/pkg/tcpip/network/ipv4/ipv4_test.go
+++ b/pkg/tcpip/network/ipv4/ipv4_test.go
@@ -396,16 +396,6 @@ func compareFragments(t *testing.T, packets []*stack.PacketBuffer, sourcePacketI
if got, want := len(ip), int(mtu); got > want {
t.Errorf("fragment is too large, got %d want %d", got, want)
}
- if i == 0 {
- got := packet.NetworkHeader().View().Size() + packet.TransportHeader().View().Size()
- // sourcePacketInfo does not have NetworkHeader added, simulate one.
- want := header.IPv4MinimumSize + sourcePacketInfo.TransportHeader().View().Size()
- // Check that it kept the transport header in packet.TransportHeader if
- // it fits in the first fragment.
- if want < int(mtu) && got != want {
- t.Errorf("first fragment hdr parts should have unmodified length if possible: got %d, want %d", got, want)
- }
- }
if got, want := packet.AvailableHeaderBytes(), sourcePacketInfo.AvailableHeaderBytes()-header.IPv4MinimumSize; got != want {
t.Errorf("fragment #%d should have the same available space for prepending as source: got %d, want %d", i, got, want)
}
@@ -435,6 +425,8 @@ func compareFragments(t *testing.T, packets []*stack.PacketBuffer, sourcePacketI
}
func TestFragmentation(t *testing.T) {
+ const ttl = 42
+
var manyPayloadViewsSizes [1000]int
for i := range manyPayloadViewsSizes {
manyPayloadViewsSizes[i] = 7
@@ -448,15 +440,15 @@ func TestFragmentation(t *testing.T) {
payloadViewsSizes []int
expectedFrags int
}{
- {"NoFragmentation", 2000, &stack.GSO{}, 0, header.IPv4MinimumSize, []int{1000}, 1},
- {"NoFragmentationWithBigHeader", 2000, &stack.GSO{}, 16, header.IPv4MinimumSize, []int{1000}, 1},
+ {"No fragmentation", 2000, &stack.GSO{}, 0, header.IPv4MinimumSize, []int{1000}, 1},
+ {"No fragmentation with big header", 2000, &stack.GSO{}, 16, header.IPv4MinimumSize, []int{1000}, 1},
{"Fragmented", 800, &stack.GSO{}, 0, header.IPv4MinimumSize, []int{1000}, 2},
- {"FragmentedWithGsoNil", 800, nil, 0, header.IPv4MinimumSize, []int{1000}, 2},
- {"FragmentedWithManyViews", 300, &stack.GSO{}, 0, header.IPv4MinimumSize, manyPayloadViewsSizes[:], 25},
- {"FragmentedWithManyViewsAndPrependableBytes", 300, &stack.GSO{}, 0, header.IPv4MinimumSize + 55, manyPayloadViewsSizes[:], 25},
- {"FragmentedWithBigHeader", 800, &stack.GSO{}, 20, header.IPv4MinimumSize, []int{1000}, 2},
- {"FragmentedWithBigHeaderAndPrependableBytes", 800, &stack.GSO{}, 20, header.IPv4MinimumSize + 66, []int{1000}, 2},
- {"FragmentedWithMTUSmallerThanHeaderAndPrependableBytes", 300, &stack.GSO{}, 1000, header.IPv4MinimumSize + 77, []int{500}, 6},
+ {"Fragmented with gso nil", 800, nil, 0, header.IPv4MinimumSize, []int{1000}, 2},
+ {"Fragmented with many views", 300, &stack.GSO{}, 0, header.IPv4MinimumSize, manyPayloadViewsSizes[:], 25},
+ {"Fragmented with many views and prependable bytes", 300, &stack.GSO{}, 0, header.IPv4MinimumSize + 55, manyPayloadViewsSizes[:], 25},
+ {"Fragmented with big header", 800, &stack.GSO{}, 20, header.IPv4MinimumSize, []int{1000}, 2},
+ {"Fragmented with big header and prependable bytes", 800, &stack.GSO{}, 20, header.IPv4MinimumSize + 66, []int{1000}, 2},
+ {"Fragmented with MTU smaller than header and prependable bytes", 300, &stack.GSO{}, 1000, header.IPv4MinimumSize + 77, []int{500}, 6},
}
for _, ft := range fragTests {
@@ -467,11 +459,11 @@ func TestFragmentation(t *testing.T) {
source := pkt.Clone()
err := r.WritePacket(ft.gso, stack.NetworkHeaderParams{
Protocol: tcp.ProtocolNumber,
- TTL: 42,
+ TTL: ttl,
TOS: stack.DefaultTOS,
}, pkt)
if err != nil {
- t.Errorf("got err = %s, want = nil", err)
+ t.Fatalf("r.WritePacket(_, _, _) = %s", err)
}
if got := len(ep.WrittenPackets); got != ft.expectedFrags {
@@ -491,48 +483,46 @@ func TestFragmentation(t *testing.T) {
// TestFragmentationErrors checks that errors are returned from write packet
// correctly.
func TestFragmentationErrors(t *testing.T) {
+ const ttl = 42
+
+ expectedError := tcpip.ErrAborted
fragTests := []struct {
description string
mtu uint32
transportHeaderLength int
- payloadViewsSizes []int
- err *tcpip.Error
+ payloadSize int
allowPackets int
fragmentCount int
}{
{
- description: "NoFrag",
+ description: "No frag",
mtu: 2000,
transportHeaderLength: 0,
- payloadViewsSizes: []int{1000},
- err: tcpip.ErrAborted,
+ payloadSize: 1000,
allowPackets: 0,
fragmentCount: 1,
},
{
- description: "ErrorOnFirstFrag",
+ description: "Error on first frag",
mtu: 500,
transportHeaderLength: 0,
- payloadViewsSizes: []int{1000},
- err: tcpip.ErrAborted,
+ payloadSize: 1000,
allowPackets: 0,
fragmentCount: 3,
},
{
- description: "ErrorOnSecondFrag",
+ description: "Error on second frag",
mtu: 500,
transportHeaderLength: 0,
- payloadViewsSizes: []int{1000},
- err: tcpip.ErrAborted,
+ payloadSize: 1000,
allowPackets: 1,
fragmentCount: 3,
},
{
- description: "ErrorOnFirstFragMTUSmallerThanHeader",
+ description: "Error on first frag MTU smaller than header",
mtu: 500,
transportHeaderLength: 1000,
- payloadViewsSizes: []int{500},
- err: tcpip.ErrAborted,
+ payloadSize: 500,
allowPackets: 0,
fragmentCount: 4,
},
@@ -540,16 +530,16 @@ func TestFragmentationErrors(t *testing.T) {
for _, ft := range fragTests {
t.Run(ft.description, func(t *testing.T) {
- ep := testutil.NewMockLinkEndpoint(ft.mtu, ft.err, ft.allowPackets)
+ ep := testutil.NewMockLinkEndpoint(ft.mtu, expectedError, ft.allowPackets)
r := buildRoute(t, ep)
- pkt := testutil.MakeRandPkt(ft.transportHeaderLength, header.IPv4MinimumSize, ft.payloadViewsSizes, header.IPv4ProtocolNumber)
+ pkt := testutil.MakeRandPkt(ft.transportHeaderLength, header.IPv4MinimumSize, []int{ft.payloadSize}, header.IPv4ProtocolNumber)
err := r.WritePacket(&stack.GSO{}, stack.NetworkHeaderParams{
Protocol: tcp.ProtocolNumber,
- TTL: 42,
+ TTL: ttl,
TOS: stack.DefaultTOS,
}, pkt)
- if err != ft.err {
- t.Errorf("got WritePacket() = %s, want = %s", err, ft.err)
+ if err != expectedError {
+ t.Errorf("got WritePacket() = %s, want = %s", err, expectedError)
}
if got, want := len(ep.WrittenPackets), int(r.Stats().IP.PacketsSent.Value()); err != nil && got != want {
t.Errorf("got len(ep.WrittenPackets) = %d, want = %d", got, want)
@@ -1317,6 +1307,7 @@ func TestReceiveFragments(t *testing.T) {
func TestWriteStats(t *testing.T) {
const nPackets = 3
+
tests := []struct {
name string
setup func(*testing.T, *stack.Stack)
@@ -1462,12 +1453,13 @@ func buildRoute(t *testing.T, ep stack.LinkEndpoint) stack.Route {
dst = "\x10\x00\x00\x02"
)
if err := s.AddAddress(1, ipv4.ProtocolNumber, src); err != nil {
- t.Fatalf("AddAddress(1, %d, _) failed: %s", ipv4.ProtocolNumber, err)
+ t.Fatalf("AddAddress(1, %d, %s) failed: %s", ipv4.ProtocolNumber, src, err)
}
{
- subnet, err := tcpip.NewSubnet(dst, tcpip.AddressMask(header.IPv4Broadcast))
+ mask := tcpip.AddressMask(header.IPv4Broadcast)
+ subnet, err := tcpip.NewSubnet(dst, mask)
if err != nil {
- t.Fatalf("NewSubnet(_, _) failed: %v", err)
+ t.Fatalf("NewSubnet(%s, %s) failed: %v", dst, mask, err)
}
s.SetRouteTable([]tcpip.Route{{
Destination: subnet,
@@ -1476,7 +1468,7 @@ func buildRoute(t *testing.T, ep stack.LinkEndpoint) stack.Route {
}
rt, err := s.FindRoute(1, src, dst, ipv4.ProtocolNumber, false /* multicastLoop */)
if err != nil {
- t.Fatalf("got FindRoute(1, _, _, %d, false) = %s, want = nil", ipv4.ProtocolNumber, err)
+ t.Fatalf("FindRoute(1, %s, %s, %d, false) = %s", src, dst, ipv4.ProtocolNumber, err)
}
return rt
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 23:52:59 +0000