/
config.go
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/
config.go
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// Copyright 2015 flannel 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 subnet
import (
"encoding/json"
"errors"
"fmt"
"math/big"
"github.com/flannel-io/flannel/pkg/ip"
)
type Config struct {
EnableIPv4 bool
EnableIPv6 bool
Network ip.IP4Net
IPv6Network ip.IP6Net
SubnetMin ip.IP4
SubnetMax ip.IP4
IPv6SubnetMin *ip.IP6
IPv6SubnetMax *ip.IP6
SubnetLen uint
IPv6SubnetLen uint
BackendType string `json:"-"`
Backend json.RawMessage `json:",omitempty"`
}
func parseBackendType(be json.RawMessage) (string, error) {
var bt struct {
Type string
}
if len(be) == 0 {
return "udp", nil
} else if err := json.Unmarshal(be, &bt); err != nil {
return "", fmt.Errorf("error decoding Backend property of config: %v", err)
}
return bt.Type, nil
}
func ParseConfig(s string) (*Config, error) {
cfg := new(Config)
// Enable ipv4 by default
cfg.EnableIPv4 = true
err := json.Unmarshal([]byte(s), cfg)
if err != nil {
return nil, err
}
if cfg.EnableIPv4 {
if cfg.Network.Empty() {
return nil, errors.New("Please define a correct Network parameter in the flannel config")
}
if cfg.SubnetLen > 0 {
// SubnetLen needs to allow for a tunnel and bridge device on each host.
if cfg.SubnetLen > 30 {
return nil, errors.New("SubnetLen must be less than /31")
}
// SubnetLen needs to fit _more_ than twice into the Network.
// the first subnet isn't used, so splitting into two one only provide one usable host.
if cfg.SubnetLen < cfg.Network.PrefixLen+2 {
return nil, errors.New("Network must be able to accommodate at least four subnets")
}
} else {
// If the network is smaller than a /28 then the network isn't big enough for flannel so return an error.
// Default to giving each host at least a /24 (as long as the network is big enough to support at least four hosts)
// Otherwise, if the network is too small to give each host a /24 just split the network into four.
if cfg.Network.PrefixLen > 28 {
// Each subnet needs at least four addresses (/30) and the network needs to accommodate at least four
// since the first subnet isn't used, so splitting into two would only provide one usable host.
// So the min useful PrefixLen is /28
return nil, errors.New("Network is too small. Minimum useful network prefix is /28")
} else if cfg.Network.PrefixLen <= 22 {
// Network is big enough to give each host a /24
cfg.SubnetLen = 24
} else {
// Use +2 to provide four hosts per subnet.
cfg.SubnetLen = cfg.Network.PrefixLen + 2
}
}
subnetSize := ip.IP4(1 << (32 - cfg.SubnetLen))
if cfg.SubnetMin == ip.IP4(0) {
// skip over the first subnet otherwise it causes problems. e.g.
// if Network is 10.100.0.0/16, having an interface with 10.100.0.0
// conflicts with the network address.
cfg.SubnetMin = cfg.Network.IP + subnetSize
} else if !cfg.Network.Contains(cfg.SubnetMin) {
return nil, errors.New("SubnetMin is not in the range of the Network")
}
if cfg.SubnetMax == ip.IP4(0) {
cfg.SubnetMax = cfg.Network.Next().IP - subnetSize
} else if !cfg.Network.Contains(cfg.SubnetMax) {
return nil, errors.New("SubnetMax is not in the range of the Network")
}
// The SubnetMin and SubnetMax need to be aligned to a SubnetLen boundary
mask := ip.IP4(0xFFFFFFFF << (32 - cfg.SubnetLen))
if cfg.SubnetMin != cfg.SubnetMin&mask {
return nil, fmt.Errorf("SubnetMin is not on a SubnetLen boundary: %v", cfg.SubnetMin)
}
if cfg.SubnetMax != cfg.SubnetMax&mask {
return nil, fmt.Errorf("SubnetMax is not on a SubnetLen boundary: %v", cfg.SubnetMax)
}
}
if cfg.EnableIPv6 {
if cfg.IPv6Network.Empty() {
return nil, errors.New("Please define a correct IPv6Network parameter in the flannel config")
}
if cfg.IPv6SubnetLen > 0 {
// SubnetLen needs to allow for a tunnel and bridge device on each host.
if cfg.IPv6SubnetLen > 126 {
return nil, errors.New("SubnetLen must be less than /127")
}
// SubnetLen needs to fit _more_ than twice into the Network.
// the first subnet isn't used, so splitting into two one only provide one usable host.
if cfg.IPv6SubnetLen < cfg.IPv6Network.PrefixLen+2 {
return nil, errors.New("Network must be able to accommodate at least four subnets")
}
} else {
// If the network is smaller than a /124 then the network isn't big enough for flannel so return an error.
// Default to giving each host at least a /64 (as long as the network is big enough to support at least four hosts)
// Otherwise, if the network is too small to give each host a /64 just split the network into four.
if cfg.IPv6Network.PrefixLen > 124 {
// Each subnet needs at least four addresses (/126) and the network needs to accommodate at least four
// since the first subnet isn't used, so splitting into two would only provide one usable host.
// So the min useful PrefixLen is /124
return nil, errors.New("IPv6Network is too small. Minimum useful network prefix is /124")
} else if cfg.IPv6Network.PrefixLen <= 62 {
// Network is big enough to give each host a /64
cfg.IPv6SubnetLen = 64
} else {
// Use +2 to provide four hosts per subnet.
cfg.IPv6SubnetLen = cfg.IPv6Network.PrefixLen + 2
}
}
ipv6SubnetSize := big.NewInt(0).Lsh(big.NewInt(1), 128-cfg.IPv6SubnetLen)
if ip.IsEmpty(cfg.IPv6SubnetMin) {
// skip over the first subnet otherwise it causes problems. e.g.
// if Network is fc00::/48, having an interface with fc00::
// conflicts with the broadcast address.
cfg.IPv6SubnetMin = ip.GetIPv6SubnetMin(cfg.IPv6Network.IP, ipv6SubnetSize)
} else if !cfg.IPv6Network.Contains(cfg.IPv6SubnetMin) {
return nil, errors.New("IPv6SubnetMin is not in the range of the IPv6Network")
}
if ip.IsEmpty(cfg.IPv6SubnetMax) {
cfg.IPv6SubnetMax = ip.GetIPv6SubnetMax(cfg.IPv6Network.Next().IP, ipv6SubnetSize)
} else if !cfg.IPv6Network.Contains(cfg.IPv6SubnetMax) {
return nil, errors.New("IPv6SubnetMax is not in the range of the IPv6Network")
}
// The SubnetMin and SubnetMax need to be aligned to a SubnetLen boundary
mask := ip.Mask(int(cfg.IPv6SubnetLen))
if !ip.CheckIPv6Subnet(cfg.IPv6SubnetMin, mask) {
return nil, fmt.Errorf("IPv6SubnetMin is not on a SubnetLen boundary: %v", cfg.IPv6SubnetMin)
}
if !ip.CheckIPv6Subnet(cfg.IPv6SubnetMax, mask) {
return nil, fmt.Errorf("IPv6SubnetMax is not on a SubnetLen boundary: %v", cfg.IPv6SubnetMax)
}
}
bt, err := parseBackendType(cfg.Backend)
if err != nil {
return nil, err
}
cfg.BackendType = bt
return cfg, nil
}