diff options
Diffstat (limited to 'pkg/tcpip/header/ndp_router_advert.go')
| -rw-r--r-- | pkg/tcpip/header/ndp_router_advert.go | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/pkg/tcpip/header/ndp_router_advert.go b/pkg/tcpip/header/ndp_router_advert.go new file mode 100644 index 000000000..bf7610863 --- /dev/null +++ b/pkg/tcpip/header/ndp_router_advert.go @@ -0,0 +1,112 @@ +// Copyright 2019 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package header + +import ( + "encoding/binary" + "time" +) + +// NDPRouterAdvert is an NDP Router Advertisement message. It will only contain +// the body of an ICMPv6 packet. +// +// See RFC 4861 section 4.2 for more details. +type NDPRouterAdvert []byte + +const ( + // NDPRAMinimumSize is the minimum size of a valid NDP Router + // Advertisement message (body of an ICMPv6 packet). + NDPRAMinimumSize = 12 + + // ndpRACurrHopLimitOffset is the byte of the Curr Hop Limit field + // within an NDPRouterAdvert. + ndpRACurrHopLimitOffset = 0 + + // ndpRAFlagsOffset is the byte with the NDP RA bit-fields/flags + // within an NDPRouterAdvert. + ndpRAFlagsOffset = 1 + + // ndpRAManagedAddrConfFlagMask is the mask of the Managed Address + // Configuration flag within the bit-field/flags byte of an + // NDPRouterAdvert. + ndpRAManagedAddrConfFlagMask = (1 << 7) + + // ndpRAOtherConfFlagMask is the mask of the Other Configuration flag + // within the bit-field/flags byte of an NDPRouterAdvert. + ndpRAOtherConfFlagMask = (1 << 6) + + // ndpRARouterLifetimeOffset is the start of the 2-byte Router Lifetime + // field within an NDPRouterAdvert. + ndpRARouterLifetimeOffset = 2 + + // ndpRAReachableTimeOffset is the start of the 4-byte Reachable Time + // field within an NDPRouterAdvert. + ndpRAReachableTimeOffset = 4 + + // ndpRARetransTimerOffset is the start of the 4-byte Retrans Timer + // field within an NDPRouterAdvert. + ndpRARetransTimerOffset = 8 + + // ndpRAOptionsOffset is the start of the NDP options in an + // NDPRouterAdvert. + ndpRAOptionsOffset = 12 +) + +// CurrHopLimit returns the value of the Curr Hop Limit field. +func (b NDPRouterAdvert) CurrHopLimit() uint8 { + return b[ndpRACurrHopLimitOffset] +} + +// ManagedAddrConfFlag returns the value of the Managed Address Configuration +// flag. +func (b NDPRouterAdvert) ManagedAddrConfFlag() bool { + return b[ndpRAFlagsOffset]&ndpRAManagedAddrConfFlagMask != 0 +} + +// OtherConfFlag returns the value of the Other Configuration flag. +func (b NDPRouterAdvert) OtherConfFlag() bool { + return b[ndpRAFlagsOffset]&ndpRAOtherConfFlagMask != 0 +} + +// RouterLifetime returns the lifetime associated with the default router. A +// value of 0 means the source of the Router Advertisement is not a default +// router and SHOULD NOT appear on the default router list. Note, a value of 0 +// only means that the router should not be used as a default router, it does +// not apply to other information contained in the Router Advertisement. +func (b NDPRouterAdvert) RouterLifetime() time.Duration { + // The field is the time in seconds, as per RFC 4861 section 4.2. + return time.Second * time.Duration(binary.BigEndian.Uint16(b[ndpRARouterLifetimeOffset:])) +} + +// ReachableTime returns the time that a node assumes a neighbor is reachable +// after having received a reachability confirmation. A value of 0 means +// that it is unspecified by the source of the Router Advertisement message. +func (b NDPRouterAdvert) ReachableTime() time.Duration { + // The field is the time in milliseconds, as per RFC 4861 section 4.2. + return time.Millisecond * time.Duration(binary.BigEndian.Uint32(b[ndpRAReachableTimeOffset:])) +} + +// RetransTimer returns the time between retransmitted Neighbor Solicitation +// messages. A value of 0 means that it is unspecified by the source of the +// Router Advertisement message. +func (b NDPRouterAdvert) RetransTimer() time.Duration { + // The field is the time in milliseconds, as per RFC 4861 section 4.2. + return time.Millisecond * time.Duration(binary.BigEndian.Uint32(b[ndpRARetransTimerOffset:])) +} + +// Options returns an NDPOptions of the the options body. +func (b NDPRouterAdvert) Options() NDPOptions { + return NDPOptions(b[ndpRAOptionsOffset:]) +} |