| // Copyright 2021 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 tcp contains internal type definitions that are not expected to be |
| // used by anyone else outside pkg/tcpip. |
| package tcp |
| |
| import ( |
| "time" |
| |
| "gvisor.dev/gvisor/pkg/tcpip" |
| ) |
| |
| // TSOffset is an offset applied to the value of the TSVal field in the TCP |
| // Timestamp option. |
| // |
| // +stateify savable |
| type TSOffset struct { |
| milliseconds uint32 |
| } |
| |
| // NewTSOffset creates a new TSOffset from milliseconds. |
| func NewTSOffset(milliseconds uint32) TSOffset { |
| return TSOffset{ |
| milliseconds: milliseconds, |
| } |
| } |
| |
| // TSVal applies the offset to now and returns the timestamp in milliseconds. |
| func (offset TSOffset) TSVal(now tcpip.MonotonicTime) uint32 { |
| return uint32(now.Sub(tcpip.MonotonicTime{}).Milliseconds()) + offset.milliseconds |
| } |
| |
| // Elapsed calculates the elapsed time given now and the echoed back timestamp. |
| func (offset TSOffset) Elapsed(now tcpip.MonotonicTime, tsEcr uint32) time.Duration { |
| return time.Duration(offset.TSVal(now)-tsEcr) * time.Millisecond |
| } |