diff options
| -rw-r--r-- | pkg/tcpip/header/ndp_router_advert.go | 75 | ||||
| -rw-r--r-- | pkg/tcpip/header/ndp_test.go | 91 |
2 files changed, 143 insertions, 23 deletions
diff --git a/pkg/tcpip/header/ndp_router_advert.go b/pkg/tcpip/header/ndp_router_advert.go index bf7610863..7e2f0c797 100644 --- a/pkg/tcpip/header/ndp_router_advert.go +++ b/pkg/tcpip/header/ndp_router_advert.go @@ -19,12 +19,72 @@ import ( "time" ) +// NDPRoutePreference is the preference values for default routers or +// more-specific routes. +// +// As per RFC 4191 section 2.1, +// +// Default router preferences and preferences for more-specific routes +// are encoded the same way. +// +// Preference values are encoded as a two-bit signed integer, as +// follows: +// +// 01 High +// 00 Medium (default) +// 11 Low +// 10 Reserved - MUST NOT be sent +// +// Note that implementations can treat the value as a two-bit signed +// integer. +// +// Having just three values reinforces that they are not metrics and +// more values do not appear to be necessary for reasonable scenarios. +type NDPRoutePreference uint8 + +const ( + // HighRoutePreference indicates a high preference, as per + // RFC 4191 section 2.1. + HighRoutePreference NDPRoutePreference = 0b01 + + // MediumRoutePreference indicates a medium preference, as per + // RFC 4191 section 2.1. + // + // This is the default preference value. + MediumRoutePreference = 0b00 + + // LowRoutePreference indicates a low preference, as per + // RFC 4191 section 2.1. + LowRoutePreference = 0b11 + + // ReservedRoutePreference is a reserved preference value, as per + // RFC 4191 section 2.1. + // + // It MUST NOT be sent. + ReservedRoutePreference = 0b10 +) + // 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. +// See RFC 4861 section 4.2 and RFC 4191 section 2.2 for more details. type NDPRouterAdvert []byte +// As per RFC 4191 section 2.2, +// +// 0 1 2 3 +// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Type | Code | Checksum | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Cur Hop Limit |M|O|H|Prf|Resvd| Router Lifetime | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Reachable Time | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Retrans Timer | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | Options ... +// +-+-+-+-+-+-+-+-+-+-+-+- const ( // NDPRAMinimumSize is the minimum size of a valid NDP Router // Advertisement message (body of an ICMPv6 packet). @@ -47,6 +107,14 @@ const ( // within the bit-field/flags byte of an NDPRouterAdvert. ndpRAOtherConfFlagMask = (1 << 6) + // ndpDefaultRouterPreferenceShift is the shift of the Prf (Default Router + // Preference) field within the flags byte of an NDPRouterAdvert. + ndpDefaultRouterPreferenceShift = 3 + + // ndpDefaultRouterPreferenceMask is the mask of the Prf (Default Router + // Preference) field within the flags byte of an NDPRouterAdvert. + ndpDefaultRouterPreferenceMask = (0b11 << ndpDefaultRouterPreferenceShift) + // ndpRARouterLifetimeOffset is the start of the 2-byte Router Lifetime // field within an NDPRouterAdvert. ndpRARouterLifetimeOffset = 2 @@ -80,6 +148,11 @@ func (b NDPRouterAdvert) OtherConfFlag() bool { return b[ndpRAFlagsOffset]&ndpRAOtherConfFlagMask != 0 } +// DefaultRouterPreference returns the Default Router Preference field. +func (b NDPRouterAdvert) DefaultRouterPreference() NDPRoutePreference { + return NDPRoutePreference((b[ndpRAFlagsOffset] & ndpDefaultRouterPreferenceMask) >> ndpDefaultRouterPreferenceShift) +} + // 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 diff --git a/pkg/tcpip/header/ndp_test.go b/pkg/tcpip/header/ndp_test.go index 1b5093e58..8fd1f7d13 100644 --- a/pkg/tcpip/header/ndp_test.go +++ b/pkg/tcpip/header/ndp_test.go @@ -126,36 +126,83 @@ func TestNDPNeighborAdvert(t *testing.T) { } func TestNDPRouterAdvert(t *testing.T) { - b := []byte{ - 64, 128, 1, 2, - 3, 4, 5, 6, - 7, 8, 9, 10, + tests := []struct { + hopLimit uint8 + managedFlag, otherConfFlag bool + prf NDPRoutePreference + routerLifetimeS uint16 + reachableTimeMS, retransTimerMS uint32 + }{ + { + hopLimit: 1, + managedFlag: false, + otherConfFlag: true, + prf: HighRoutePreference, + routerLifetimeS: 2, + reachableTimeMS: 3, + retransTimerMS: 4, + }, + { + hopLimit: 64, + managedFlag: true, + otherConfFlag: false, + prf: LowRoutePreference, + routerLifetimeS: 258, + reachableTimeMS: 78492, + retransTimerMS: 13213, + }, } - ra := NDPRouterAdvert(b) + for i, test := range tests { + t.Run(fmt.Sprintf("%d", i), func(t *testing.T) { + flags := uint8(0) + if test.managedFlag { + flags |= 1 << 7 + } + if test.otherConfFlag { + flags |= 1 << 6 + } + flags |= uint8(test.prf) << 3 - if got := ra.CurrHopLimit(); got != 64 { - t.Errorf("got ra.CurrHopLimit = %d, want = 64", got) - } + b := []byte{ + test.hopLimit, flags, 1, 2, + 3, 4, 5, 6, + 7, 8, 9, 10, + } + binary.BigEndian.PutUint16(b[2:], test.routerLifetimeS) + binary.BigEndian.PutUint32(b[4:], test.reachableTimeMS) + binary.BigEndian.PutUint32(b[8:], test.retransTimerMS) - if got := ra.ManagedAddrConfFlag(); !got { - t.Errorf("got ManagedAddrConfFlag = false, want = true") - } + ra := NDPRouterAdvert(b) - if got := ra.OtherConfFlag(); got { - t.Errorf("got OtherConfFlag = true, want = false") - } + if got := ra.CurrHopLimit(); got != test.hopLimit { + t.Errorf("got ra.CurrHopLimit() = %d, want = %d", got, test.hopLimit) + } - if got, want := ra.RouterLifetime(), time.Second*258; got != want { - t.Errorf("got ra.RouterLifetime = %d, want = %d", got, want) - } + if got := ra.ManagedAddrConfFlag(); got != test.managedFlag { + t.Errorf("got ManagedAddrConfFlag() = %t, want = %t", got, test.managedFlag) + } - if got, want := ra.ReachableTime(), time.Millisecond*50595078; got != want { - t.Errorf("got ra.ReachableTime = %d, want = %d", got, want) - } + if got := ra.OtherConfFlag(); got != test.otherConfFlag { + t.Errorf("got OtherConfFlag() = %t, want = %t", got, test.otherConfFlag) + } + + if got := ra.DefaultRouterPreference(); got != test.prf { + t.Errorf("got DefaultRouterPreference() = %d, want = %d", got, test.prf) + } - if got, want := ra.RetransTimer(), time.Millisecond*117967114; got != want { - t.Errorf("got ra.RetransTimer = %d, want = %d", got, want) + if got, want := ra.RouterLifetime(), time.Second*time.Duration(test.routerLifetimeS); got != want { + t.Errorf("got ra.RouterLifetime() = %d, want = %d", got, want) + } + + if got, want := ra.ReachableTime(), time.Millisecond*time.Duration(test.reachableTimeMS); got != want { + t.Errorf("got ra.ReachableTime() = %d, want = %d", got, want) + } + + if got, want := ra.RetransTimer(), time.Millisecond*time.Duration(test.retransTimerMS); got != want { + t.Errorf("got ra.RetransTimer() = %d, want = %d", got, want) + } + }) } } |