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utils.go
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utils.go
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/*
*
* Copyright 2018 gRPC 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 conn
import core "google.golang.org/grpc/credentials/alts/internal"
// NewOutCounter returns an outgoing counter initialized to the starting sequence
// number for the client/server side of a connection.
func NewOutCounter(s core.Side, overflowLen int) (c Counter) {
c.overflowLen = overflowLen
if s == core.ServerSide {
// Server counters in ALTS record have the little-endian high bit
// set.
c.value[counterLen-1] = 0x80
}
return
}
// NewInCounter returns an incoming counter initialized to the starting sequence
// number for the client/server side of a connection. This is used in ALTS record
// to check that incoming counters are as expected, since ALTS record guarantees
// that messages are unwrapped in the same order that the peer wrapped them.
func NewInCounter(s core.Side, overflowLen int) (c Counter) {
c.overflowLen = overflowLen
if s == core.ClientSide {
// Server counters in ALTS record have the little-endian high bit
// set.
c.value[counterLen-1] = 0x80
}
return
}
// CounterFromValue creates a new counter given an initial value.
func CounterFromValue(value []byte, overflowLen int) (c Counter) {
c.overflowLen = overflowLen
copy(c.value[:], value)
return
}
// CounterSide returns the connection side (client/server) a sequence counter is
// associated with.
func CounterSide(c []byte) core.Side {
if c[counterLen-1]&0x80 == 0x80 {
return core.ServerSide
}
return core.ClientSide
}