add ability to filter routes based on headers

proxy/mucp/mucp.go

@@ -16,6 +16,7 @@ import (
 	"github.com/micro/go-micro/codec/bytes"
 	"github.com/micro/go-micro/config/options"
 	"github.com/micro/go-micro/errors"
+	"github.com/micro/go-micro/metadata"
 	"github.com/micro/go-micro/proxy"
 	"github.com/micro/go-micro/router"
 	"github.com/micro/go-micro/server"
@@ -105,6 +106,63 @@ func toSlice(r map[uint64]router.Route) []router.Route {
 	return routes
 }
 
+func (p *Proxy) filterRoutes(ctx context.Context, routes []router.Route) []router.Route {
+	md, ok := metadata.FromContext(ctx)
+	if !ok {
+		return routes
+	}
+
+	var filteredRoutes []router.Route
+
+	// filter the routes based on our headers
+	for _, route := range routes {
+		// process only routes for this id
+		if id := md["Micro-Router"]; len(id) > 0 {
+			if route.Router != id {
+				// skip routes that don't mwatch
+				continue
+			}
+		}
+
+		// only process routes with this network
+		if net := md["Micro-Network"]; len(net) > 0 {
+			if route.Network != net {
+				// skip routes that don't mwatch
+				continue
+			}
+		}
+
+		// process only this gateway
+		if gw := md["Micro-Gateway"]; len(gw) > 0 {
+			// if the gateway matches our address
+			// special case, take the routes with no gateway
+			// TODO: should we strip the gateway from the context?
+			if gw == p.Router.Options().Address {
+				if len(route.Gateway) > 0 && route.Gateway != gw {
+					continue
+				}
+				// otherwise its a local route and we're keeping it
+			} else {
+				// gateway does not match our own
+				if route.Gateway != gw {
+					continue
+				}
+			}
+		}
+
+		// TODO: address based filtering
+		// address := md["Micro-Address"]
+
+		// TODO: label based filtering
+		// requires new field in routing table : route.Labels
+
+		// passed the filter checks
+		filteredRoutes = append(filteredRoutes, route)
+	}
+
+	return filteredRoutes
+}
+
 func (p *Proxy) getLink(r router.Route) (client.Client, error) {
 	if r.Link == "local" || len(p.Links) == 0 {
 		return p.Client, nil
@@ -116,13 +174,14 @@ func (p *Proxy) getLink(r router.Route) (client.Client, error) {
 	return l, nil
 }
 
-func (p *Proxy) getRoute(service string) ([]router.Route, error) {
+func (p *Proxy) getRoute(ctx context.Context, service string) ([]router.Route, error) {
 	// lookup the route cache first
 	p.Lock()
 	cached, ok := p.Routes[service]
 	if ok {
 		p.Unlock()
-		return toSlice(cached), nil
+		routes := toSlice(cached)
+		return p.filterRoutes(ctx, routes), nil
 	}
 	p.Unlock()
 
@@ -132,7 +191,7 @@ func (p *Proxy) getRoute(service string) ([]router.Route, error) {
 		return nil, err
 	}
 
-	return routes, nil
+	return p.filterRoutes(ctx, routes), nil
 }
 
 func (p *Proxy) cacheRoutes(service string) ([]router.Route, error) {
@@ -255,7 +314,7 @@ func (p *Proxy) ServeRequest(ctx context.Context, req server.Request, rsp server
 			addresses = []string{p.Endpoint}
 		} else {
 			// get route for endpoint from router
-			addr, err := p.getRoute(p.Endpoint)
+			addr, err := p.getRoute(ctx, p.Endpoint)
 			if err != nil {
 				return err
 			}
@@ -267,7 +326,7 @@ func (p *Proxy) ServeRequest(ctx context.Context, req server.Request, rsp server
 	} else {
 		// no endpoint was specified just lookup the route
 		// get route for endpoint from router
-		addr, err := p.getRoute(service)
+		addr, err := p.getRoute(ctx, service)
 		if err != nil {
 			return err
 		}