Move router and proxy into network package

network/router/default_table.go

@@ -0,0 +1,289 @@
+package router
+
+import (
+	"fmt"
+	"hash"
+	"hash/fnv"
+	"strings"
+	"sync"
+
+	"github.com/google/uuid"
+	"github.com/olekukonko/tablewriter"
+)
+
+// TableOptions are routing table options
+// TODO: table options TBD in the future
+type TableOptions struct{}
+
+// table is in memory routing table
+type table struct {
+	// opts are table options
+	opts TableOptions
+	// m stores routing table map
+	m map[string]map[uint64]Route
+	// h hashes route entries
+	h hash.Hash64
+	// w is a list of table watchers
+	w map[string]*tableWatcher
+	sync.RWMutex
+}
+
+// newTable creates in memory routing table and returns it
+func newTable(opts ...TableOption) Table {
+	// default options
+	var options TableOptions
+
+	// apply requested options
+	for _, o := range opts {
+		o(&options)
+	}
+
+	h := fnv.New64()
+	h.Reset()
+
+	return &table{
+		opts: options,
+		m:    make(map[string]map[uint64]Route),
+		w:    make(map[string]*tableWatcher),
+		h:    h,
+	}
+}
+
+// Init initializes routing table with options
+func (t *table) Init(opts ...TableOption) error {
+	for _, o := range opts {
+		o(&t.opts)
+	}
+	return nil
+}
+
+// Options returns routing table options
+func (t *table) Options() TableOptions {
+	return t.opts
+}
+
+// Add adds a route to the routing table
+func (t *table) Add(r Route) error {
+	destAddr := r.Destination
+	sum := t.hash(r)
+
+	t.Lock()
+	defer t.Unlock()
+
+	// check if the destination has any routes in the table
+	if _, ok := t.m[destAddr]; !ok {
+		t.m[destAddr] = make(map[uint64]Route)
+		t.m[destAddr][sum] = r
+		go t.sendEvent(&Event{Type: CreateEvent, Route: r})
+		return nil
+	}
+
+	// add new route to the table for the given destination
+	if _, ok := t.m[destAddr][sum]; !ok {
+		t.m[destAddr][sum] = r
+		go t.sendEvent(&Event{Type: CreateEvent, Route: r})
+		return nil
+	}
+
+	// only add the route if the route override is explicitly requested
+	if _, ok := t.m[destAddr][sum]; ok && r.Policy == OverrideIfExists {
+		t.m[destAddr][sum] = r
+		go t.sendEvent(&Event{Type: UpdateEvent, Route: r})
+		return nil
+	}
+
+	// if we reached this point without already returning the route already exists
+	// we return nil only if explicitly requested by the client
+	if r.Policy == IgnoreIfExists {
+		return nil
+	}
+
+	return ErrDuplicateRoute
+}
+
+// Delete deletes the route from the routing table
+func (t *table) Delete(r Route) error {
+	t.Lock()
+	defer t.Unlock()
+
+	destAddr := r.Destination
+	sum := t.hash(r)
+
+	if _, ok := t.m[destAddr]; !ok {
+		return ErrRouteNotFound
+	}
+
+	delete(t.m[destAddr], sum)
+	go t.sendEvent(&Event{Type: DeleteEvent, Route: r})
+
+	return nil
+}
+
+// Update updates routing table with new route
+func (t *table) Update(r Route) error {
+	destAddr := r.Destination
+	sum := t.hash(r)
+
+	t.Lock()
+	defer t.Unlock()
+
+	// check if the destAddr has ANY routes in the table
+	if _, ok := t.m[destAddr]; !ok {
+		return ErrRouteNotFound
+	}
+
+	// if the route has been found update it
+	if _, ok := t.m[destAddr][sum]; ok {
+		t.m[destAddr][sum] = r
+		go t.sendEvent(&Event{Type: UpdateEvent, Route: r})
+		return nil
+	}
+
+	return ErrRouteNotFound
+}
+
+// List returns a list of all routes in the table
+func (t *table) List() ([]Route, error) {
+	t.RLock()
+	defer t.RUnlock()
+
+	var routes []Route
+	for _, rmap := range t.m {
+		for _, route := range rmap {
+			routes = append(routes, route)
+		}
+	}
+
+	return routes, nil
+}
+
+// Lookup queries routing table and returns all routes that match it
+func (t *table) Lookup(q Query) ([]Route, error) {
+	t.RLock()
+	defer t.RUnlock()
+
+	var results []Route
+
+	for destAddr, routes := range t.m {
+		if q.Options().Destination != "*" {
+			if q.Options().Destination != destAddr {
+				continue
+			}
+			for _, route := range routes {
+				if q.Options().Network == "*" || q.Options().Network == route.Network {
+					if q.Options().Router.ID() == "*" || q.Options().Router.ID() == route.Router.ID() {
+						if route.Metric <= q.Options().Metric {
+							results = append(results, route)
+						}
+					}
+				}
+			}
+		}
+
+		if q.Options().Destination == "*" {
+			for _, route := range routes {
+				if q.Options().Network == "*" || q.Options().Network == route.Router.Network() {
+					if q.Options().Router.ID() == "*" || q.Options().Router.ID() == route.Router.ID() {
+						if route.Metric <= q.Options().Metric {
+							results = append(results, route)
+						}
+					}
+				}
+			}
+		}
+	}
+
+	if len(results) == 0 && q.Options().Policy != DiscardNoRoute {
+		return nil, ErrRouteNotFound
+	}
+
+	return results, nil
+}
+
+// Watch returns routing table entry watcher
+func (t *table) Watch(opts ...WatchOption) (Watcher, error) {
+	// by default watch everything
+	wopts := WatchOptions{
+		Destination: "*",
+		Network:     "*",
+	}
+
+	for _, o := range opts {
+		o(&wopts)
+	}
+
+	watcher := &tableWatcher{
+		opts:    wopts,
+		resChan: make(chan *Event, 10),
+		done:    make(chan struct{}),
+	}
+
+	t.Lock()
+	t.w[uuid.New().String()] = watcher
+	t.Unlock()
+
+	return watcher, nil
+}
+
+// sendEvent sends rules to all subscribe watchers
+func (t *table) sendEvent(r *Event) {
+	t.RLock()
+	defer t.RUnlock()
+
+	for _, w := range t.w {
+		select {
+		case w.resChan <- r:
+		case <-w.done:
+		}
+	}
+}
+
+// Size returns the size of the routing table
+func (t *table) Size() int {
+	t.RLock()
+	defer t.RUnlock()
+
+	return len(t.m)
+}
+
+// String returns debug information
+func (t *table) String() string {
+	t.RLock()
+	defer t.RUnlock()
+
+	// this will help us build routing table string
+	sb := &strings.Builder{}
+
+	// create nice table printing structure
+	table := tablewriter.NewWriter(sb)
+	table.SetHeader([]string{"Destination", "Router", "Network", "Metric"})
+
+	for _, destRoute := range t.m {
+		for _, route := range destRoute {
+			strRoute := []string{
+				route.Destination,
+				route.Router.Address(),
+				route.Network,
+				fmt.Sprintf("%d", route.Metric),
+			}
+			table.Append(strRoute)
+		}
+	}
+
+	// render table into sb
+	table.Render()
+
+	return sb.String()
+}
+
+// hash hashes the route using router gateway and network address
+func (t *table) hash(r Route) uint64 {
+	destAddr := r.Destination
+	routerAddr := r.Router.Address()
+	netAddr := r.Network
+
+	t.h.Reset()
+	t.h.Write([]byte(destAddr + routerAddr + netAddr))
+
+	return t.h.Sum64()
+}