2019-06-07 01:29:24 +03:00
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package router
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2019-06-07 19:20:22 +03:00
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import (
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"errors"
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"fmt"
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"hash"
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2019-06-10 01:09:38 +03:00
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"hash/fnv"
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"strings"
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"sync"
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"github.com/olekukonko/tablewriter"
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2019-06-07 19:20:22 +03:00
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)
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2019-06-07 01:29:24 +03:00
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var (
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// ErrRouteNotFound is returned when no route was found
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ErrRouteNotFound = errors.New("route not found")
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// ErrDuplicateRoute is return when route already exists
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ErrDuplicateRoute = errors.New("duplicate route")
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// ErrNotImplemented is returned when some functionality has not been implemented
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ErrNotImplemented = errors.New("not implemented")
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)
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// Table is routing table
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type Table interface {
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// Add adds new route to the table
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Add(Route) error
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// Remove removes route from the table
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Remove(Route) error
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// Update updates route in the table
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Update(...RouteOption) error
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// Lookup looks up routes in the table
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Lookup(Query) ([]Route, error)
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// Size returns the size of the table
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Size() int
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// String prints the routing table
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String() string
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}
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// table is routing table
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// It maps service name to routes
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type table struct {
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// m stores routing table map
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m map[uint64]Route
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// h is a hasher hashes route entries
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h hash.Hash64
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sync.RWMutex
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}
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// NewTable creates new routing table and returns it
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func NewTable() Table {
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h := fnv.New64()
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h.Reset()
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return &table{
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m: make(map[uint64]Route),
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h: h,
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}
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}
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// Add adds new routing entry
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func (t *table) Add(r Route) error {
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t.Lock()
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defer t.Unlock()
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sum := t.hash(r)
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if _, ok := t.m[sum]; !ok {
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t.m[sum] = r
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return nil
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}
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if _, ok := t.m[sum]; ok && r.Options().Policy == OverrideIfExists {
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t.m[sum] = r
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return nil
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}
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return ErrDuplicateRoute
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}
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// Remove removes entry from the routing table
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func (t *table) Remove(r Route) error {
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t.Lock()
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defer t.Unlock()
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sum := t.hash(r)
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if _, ok := t.m[sum]; !ok {
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return ErrRouteNotFound
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}
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delete(t.m, sum)
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return nil
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}
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// Update updates routing entry
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func (t *table) Update(opts ...RouteOption) error {
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t.Lock()
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defer t.Unlock()
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r := NewRoute(opts...)
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sum := t.hash(r)
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if _, ok := t.m[sum]; !ok {
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return ErrRouteNotFound
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}
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if _, ok := t.m[sum]; ok {
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t.m[sum] = r
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return nil
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}
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return ErrRouteNotFound
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}
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// Lookup looks up entry in the routing table
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func (t *table) Lookup(q Query) ([]Route, error) {
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return nil, ErrNotImplemented
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}
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// Size returns the size of the routing table
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func (t *table) Size() int {
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t.RLock()
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defer t.RUnlock()
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return len(t.m)
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}
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// String returns text representation of routing table
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func (t *table) String() string {
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t.RLock()
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defer t.RUnlock()
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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{"Dest", "Hop", "Src", "Metric"})
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for _, route := range t.m {
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strRoute := []string{
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route.Options().DestAddr,
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route.Options().Hop.Address(),
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fmt.Sprintf("%d", route.Options().SrcAddr),
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fmt.Sprintf("%d", route.Options().Metric),
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}
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table.Append(strRoute)
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}
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return sb.String()
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}
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func (t *table) hash(r Route) uint64 {
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srcAddr := r.Options().SrcAddr
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destAddr := r.Options().DestAddr
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routerAddr := r.Options().Hop.Address()
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t.h.Reset()
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t.h.Write([]byte(srcAddr + destAddr + routerAddr))
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return t.h.Sum64()
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}
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