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tcp.go
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tcp.go
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// Copyright 2020 Authors of Hubble
//
// 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 filters
import (
"context"
"fmt"
flowpb "github.com/cilium/cilium/api/v1/flow"
v1 "github.com/cilium/cilium/pkg/hubble/api/v1"
)
func filterByTCPFlags(flags []*flowpb.TCPFlags) (FilterFunc, error) {
return func(ev *v1.Event) bool {
l4tcp := ev.GetFlow().GetL4().GetTCP()
if l4tcp == nil {
return false
}
flowFlags := l4tcp.GetFlags()
// check if the TCP event has any of the flags mentioned in flowfilter
// example: if TCP event has flags SYN and ACK set and if the flowfilter
// only has SYN, then this event should be accepted by the filter.
for _, f := range flags {
switch {
case f.FIN && !flowFlags.FIN,
f.SYN && !flowFlags.SYN,
f.RST && !flowFlags.RST,
f.PSH && !flowFlags.PSH,
f.ACK && !flowFlags.ACK,
f.URG && !flowFlags.URG,
f.ECE && !flowFlags.ECE,
f.CWR && !flowFlags.CWR,
f.NS && !flowFlags.NS:
continue
}
return true
}
return false
}, nil
}
// TCPFilter implements filtering based on TCP protocol header
type TCPFilter struct{}
// OnBuildFilter builds a TCP protocol based filter
func (p *TCPFilter) OnBuildFilter(ctx context.Context, ff *flowpb.FlowFilter) ([]FilterFunc, error) {
var fs []FilterFunc
if ff.GetTcpFlags() != nil {
pf, err := filterByTCPFlags(ff.GetTcpFlags())
if err != nil {
return nil, fmt.Errorf("invalid tcp flags filter: %w", err)
}
fs = append(fs, pf)
}
return fs, nil
}