141 lines
2.7 KiB
Go
141 lines
2.7 KiB
Go
package router
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import (
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"fmt"
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"strings"
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"github.com/olekukonko/tablewriter"
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)
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var (
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// DefaultLocalMetric is default route cost for local network
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DefaultLocalMetric = 1
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// DefaultNetworkMetric is default route cost for micro network
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DefaultNetworkMetric = 10
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)
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// AddPolicy defines routing table addition policy
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type AddPolicy int
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const (
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// OverrideIfExists overrides route if it already exists
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OverrideIfExists AddPolicy = iota
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// IgnoreIfExists does not modify existing route
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IgnoreIfExists
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)
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// String returns human reprensentation of policy
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func (p AddPolicy) String() string {
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switch p {
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case OverrideIfExists:
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return "OVERRIDE"
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case IgnoreIfExists:
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return "IGNORE"
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default:
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return "UNKNOWN"
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}
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}
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// RouteOption is used to set routing table entry options
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type RouteOption func(*RouteOptions)
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// RouteOptions are route options
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type RouteOptions struct {
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// DestAddr is destination address
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DestAddr string
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// Gateway is the next route hop
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Gateway Router
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// Network defines micro network
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Network string
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// Metric is route cost metric
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Metric int
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// Policy defines route addition policy
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Policy AddPolicy
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}
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// DestAddr sets destination address
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func DestAddr(a string) RouteOption {
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return func(o *RouteOptions) {
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o.DestAddr = a
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}
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}
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// Gateway sets the route gateway
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func Gateway(r Router) RouteOption {
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return func(o *RouteOptions) {
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o.Gateway = r
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}
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}
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// Network sets micro network
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func Network(n string) RouteOption {
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return func(o *RouteOptions) {
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o.Network = n
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}
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}
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// Metric sets route metric
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func Metric(m int) RouteOption {
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return func(o *RouteOptions) {
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o.Metric = m
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}
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}
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// RoutePolicy sets add route policy
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func RoutePolicy(p AddPolicy) RouteOption {
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return func(o *RouteOptions) {
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o.Policy = p
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}
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}
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// Route is routing table route
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type Route interface {
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// Options returns route options
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Options() RouteOptions
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}
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type route struct {
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opts RouteOptions
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}
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// NewRoute returns new routing table route
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func NewRoute(opts ...RouteOption) Route {
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eopts := RouteOptions{}
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for _, o := range opts {
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o(&eopts)
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}
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return &route{
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opts: eopts,
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}
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}
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// Options returns route options
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func (r *route) Options() RouteOptions {
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return r.opts
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}
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// String allows to print the route
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func (r *route) String() string {
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// this will help us build routing table string
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sb := &strings.Builder{}
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// create nice table printing structure
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table := tablewriter.NewWriter(sb)
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table.SetHeader([]string{"Destination", "Gateway", "Network", "Metric"})
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strRoute := []string{
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r.opts.DestAddr,
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r.opts.Gateway.Address(),
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r.opts.Network,
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fmt.Sprintf("%d", r.opts.Metric),
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}
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table.Append(strRoute)
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// render table into sb
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table.Render()
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return sb.String()
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}
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