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// 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 iptables supports packet filtering and manipulation via the iptables
// tool.
package iptables
const (
tablenameNat = "nat"
tablenameMangle = "mangle"
)
// Chain names as defined by net/ipv4/netfilter/ip_tables.c.
const (
chainNamePrerouting = "PREROUTING"
chainNameInput = "INPUT"
chainNameForward = "FORWARD"
chainNameOutput = "OUTPUT"
chainNamePostrouting = "POSTROUTING"
)
// DefaultTables returns a default set of tables. Each chain is set to accept
// all packets.
func DefaultTables() *IPTables {
tables := IPTables{
Tables: map[string]*Table{
tablenameNat: &Table{
BuiltinChains: map[Hook]*Chain{
Prerouting: unconditionalAcceptChain(chainNamePrerouting),
Input: unconditionalAcceptChain(chainNameInput),
Output: unconditionalAcceptChain(chainNameOutput),
Postrouting: unconditionalAcceptChain(chainNamePostrouting),
},
DefaultTargets: map[Hook]Target{
Prerouting: UnconditionalAcceptTarget{},
Input: UnconditionalAcceptTarget{},
Output: UnconditionalAcceptTarget{},
Postrouting: UnconditionalAcceptTarget{},
},
UserChains: map[string]*Chain{},
},
tablenameMangle: &Table{
BuiltinChains: map[Hook]*Chain{
Prerouting: unconditionalAcceptChain(chainNamePrerouting),
Output: unconditionalAcceptChain(chainNameOutput),
},
DefaultTargets: map[Hook]Target{
Prerouting: UnconditionalAcceptTarget{},
Output: UnconditionalAcceptTarget{},
},
UserChains: map[string]*Chain{},
},
},
Priorities: map[Hook][]string{
Prerouting: []string{tablenameMangle, tablenameNat},
Output: []string{tablenameMangle, tablenameNat},
},
}
// Initialize each table's Chains field.
tables.Tables[tablenameNat].Chains = map[string]*Chain{
chainNamePrerouting: tables.Tables[tablenameNat].BuiltinChains[Prerouting],
chainNameInput: tables.Tables[tablenameNat].BuiltinChains[Input],
chainNameOutput: tables.Tables[tablenameNat].BuiltinChains[Output],
chainNamePostrouting: tables.Tables[tablenameNat].BuiltinChains[Postrouting],
}
tables.Tables[tablenameMangle].Chains = map[string]*Chain{
chainNamePrerouting: tables.Tables[tablenameMangle].BuiltinChains[Prerouting],
chainNameInput: tables.Tables[tablenameMangle].BuiltinChains[Input],
chainNameOutput: tables.Tables[tablenameMangle].BuiltinChains[Output],
chainNamePostrouting: tables.Tables[tablenameMangle].BuiltinChains[Postrouting],
}
return &tables
}
func unconditionalAcceptChain(name string) *Chain {
return &Chain{
Name: name,
Rules: []*Rule{
&Rule{
Target: UnconditionalAcceptTarget{},
},
},
}
}
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