Yang library advertisement and yang file download

rest/main/main.go

@@ -25,13 +25,14 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
+	"net"
 	"net/http"
 	"os"
 	"os/signal"
 	"syscall"
 
-	"github.com/Azure/sonic-mgmt-framework/rest/server"
 	"github.com/Azure/sonic-mgmt-framework/build/rest_server/dist/swagger"
+	"github.com/Azure/sonic-mgmt-framework/rest/server"
 	"github.com/golang/glog"
 	"github.com/pkg/profile"
 )
@@ -82,6 +83,9 @@ func main() {
 	if clientAuth == "user" {
 		rtrConfig.AuthEnable = true
 	}
+	if ip := findAManagementIP(); ip != "" {
+		rtrConfig.ServerAddr = fmt.Sprintf("https://%s:%d", ip, port)
+	}
 
 	router := server.NewRouter(rtrConfig)
 
@@ -190,3 +194,27 @@ func getPreferredCipherSuites() []uint16 {
 		tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
 	}
 }
+
+// findAManagementIP returns a valid IPv4 address of eth0.
+// Empty string is returned if no address could be resolved.
+func findAManagementIP() string {
+	var addrs []net.Addr
+	eth0, err := net.InterfaceByName("eth0")
+	if err == nil {
+		addrs, err = eth0.Addrs()
+	}
+	if err != nil {
+		glog.Errorf("Could not read eth0 info; err=%v", err)
+		return ""
+	}
+
+	for _, addr := range addrs {
+		ip, _, err := net.ParseCIDR(addr.String())
+		if err == nil && ip.To4() != nil {
+			return ip.String()
+		}
+	}
+
+	glog.Warning("Could not find a management address!!")
+	return ""
+}

rest/server/restconf.go

@@ -45,6 +45,9 @@ func init() {
 	// Metadata discovery handler
 	AddRoute("hostMetadataHandler", "GET", "/.well-known/host-meta", hostMetadataHandler)
 
+	// yanglib version handler
+	AddRoute("yanglibVersionHandler", "GET", "/restconf/yang-library-version", yanglibVersionHandler)
+
 	// RESTCONF capability handler
 	AddRoute("capabilityHandler", "GET",
 		"/restconf/data/ietf-restconf-monitoring:restconf-state/capabilities", capabilityHandler)
@@ -66,6 +69,27 @@ func hostMetadataHandler(w http.ResponseWriter, r *http.Request) {
 	w.Write(data.Bytes())
 }
 
+// yanglibVersionHandler handles "GET /restconf/yang-library-version"
+// request as per RFC8040. Yanglib version supported is "2016-06-21"
+func yanglibVersionHandler(w http.ResponseWriter, r *http.Request) {
+	var data bytes.Buffer
+	var contentType string
+	accept := r.Header.Get("Accept")
+
+	// Rudimentary content negotiation
+	if strings.Contains(accept, mimeYangDataXML) {
+		contentType = mimeYangDataXML
+		data.WriteString("<yang-library-version xmlns='urn:ietf:params:xml:ns:yang:ietf-restconf'>")
+		data.WriteString("2016-06-21</yang-library-version>")
+	} else {
+		contentType = mimeYangDataJSON
+		data.WriteString("{\"ietf-restconf:yang-library-version\": \"2016-06-21\"}")
+	}
+
+	w.Header().Set("Content-Type", contentType)
+	w.Write(data.Bytes())
+}
+
 // capabilityHandler serves RESTCONF capability requests -
 // "GET /restconf/data/ietf-restconf-monitoring:restconf-state/capabilities"
 func capabilityHandler(w http.ResponseWriter, r *http.Request) {

rest/server/restconf_test.go

@@ -78,6 +78,63 @@ func TestMetaHandler(t *testing.T) {
 	}
 }
 
+func TestYanglibVer_json(t *testing.T) {
+	testYanglibVer(t, mimeYangDataJSON, mimeYangDataJSON)
+}
+
+func TestYanglibVer_xml(t *testing.T) {
+	testYanglibVer(t, mimeYangDataXML, mimeYangDataXML)
+}
+
+func TestYanglibVer_default(t *testing.T) {
+	testYanglibVer(t, "", mimeYangDataJSON)
+}
+
+func TestYanglibVer_unknown(t *testing.T) {
+	testYanglibVer(t, "text/plain", mimeYangDataJSON)
+}
+
+func testYanglibVer(t *testing.T, requestAcceptType, expectedContentType string) {
+	w := httptest.NewRecorder()
+	r := httptest.NewRequest("GET", "/restconf/yang-library-version", nil)
+	if requestAcceptType != "" {
+		r.Header.Set("Accept", requestAcceptType)
+	}
+
+	t.Logf("GET /restconf/yang-library-version with accept=%s", requestAcceptType)
+	newDefaultRouter().ServeHTTP(w, r)
+
+	if w.Code != 200 {
+		t.Fatalf("Request failed with status %d", w.Code)
+	}
+	if len(w.Body.Bytes()) == 0 {
+		t.Fatalf("No response body")
+	}
+	if w.Header().Get("Content-Type") != expectedContentType {
+		t.Fatalf("Expected content-type=%s, found=%s", expectedContentType, w.Header().Get("Content-Type"))
+	}
+
+	var err error
+	var resp struct {
+		XMLName xml.Name `json:"-" xml:"urn:ietf:params:xml:ns:yang:ietf-restconf yang-library-version"`
+		Version string   `json:"ietf-restconf:yang-library-version" xml:",chardata"`
+	}
+
+	if expectedContentType == mimeYangDataXML {
+		err = xml.Unmarshal(w.Body.Bytes(), &resp)
+	} else {
+		err = json.Unmarshal(w.Body.Bytes(), &resp)
+	}
+	if err != nil {
+		t.Fatalf("Response parsing failed; err=%v", err)
+	}
+
+	t.Logf("GOT yang-library-version %s; content-type=%s", resp.Version, w.Header().Get("Content-Type"))
+	if resp.Version != "2016-06-21" {
+		t.Fatalf("Expected yanglib version 2016-06-21; received=%s", resp.Version)
+	}
+}
+
 func TestCapability_1(t *testing.T) {
 	testCapability(t, "/restconf/data/ietf-restconf-monitoring:restconf-state/capabilities")
 }

rest/server/router.go

@@ -27,6 +27,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Azure/sonic-mgmt-common/translib"
 	"github.com/golang/glog"
 	"github.com/gorilla/mux"
 )
@@ -51,6 +52,10 @@ type Router struct {
 type RouterConfig struct {
 	// AuthEnable indicates if client authentication is enabled
 	AuthEnable bool
+
+	// ServerAddr is the address to contact main server. Will be used to
+	// advertise the server's address (like yang download path).. Optional
+	ServerAddr string
 }
 
 // ServeHTTP resolves and invokes the handler for http request r.
@@ -298,7 +303,7 @@ func NewRouter(config RouterConfig) *Router {
 		allRoutes.rcRouteCount, allRoutes.muxRouteCount)
 
 	// Add internal service API routes if not added already
-	allRoutes.addServiceRoutes()
+	allRoutes.addServiceRoutes(&config)
 
 	router := &Router{
 		config: config,
@@ -322,8 +327,6 @@ type routeStore struct {
 	muxOptsHandler http.Handler        // OPTIONS handler for mux routes
 	muxOptsData    map[string][]string // path to operations map for mux routes
 	muxRouteCount  uint32              // number of routes in mux router
-
-	svcRoutesAdded bool // indicates if service routes have been registered
 }
 
 // newRouteStore creates an empty routeStore instance.
@@ -363,23 +366,33 @@ func (rs *routeStore) addMuxRoute(rr *routeRegInfo) {
 	rs.muxRouteCount++
 }
 
-// finish creates routes for all internal service API handlers in
+// addServiceRoutes creates routes for all internal service API handlers in
 // mux router. Should be called after all REST API routes are added.
-func (rs *routeStore) addServiceRoutes() {
-	if rs.svcRoutesAdded {
-		return
-	}
-
-	rs.svcRoutesAdded = true
+func (rs *routeStore) addServiceRoutes(config *RouterConfig) {
 	router := rs.muxRoutes
 
 	// Documentation and test UI
-	uiHandler := http.StripPrefix("/ui/", http.FileServer(http.Dir(swaggerUIDir)))
-	router.Methods("GET").PathPrefix("/ui/").Handler(uiHandler)
+	if router.Get("swaggerUI") == nil {
+		rs.addFilesystemRoute("swaggerUI", "/ui/", swaggerUIDir)
+
+		// Redirect "/ui" to "/ui/index.html"
+		router.Methods("GET").Path("/ui").
+			Handler(http.RedirectHandler("/ui/index.html", http.StatusMovedPermanently))
+	}
+
+	// Yang download
+	if config.ServerAddr != "" && router.Get("yangDownload") == nil {
+		yangPrefix := "/models/yang/"
+		translib.SetSchemaRootURL(strings.TrimSuffix(config.ServerAddr, "/") + yangPrefix)
+		rs.addFilesystemRoute("yangDownload", yangPrefix, translib.GetYangPath())
+	}
+}
 
-	// Redirect "/ui" to "/ui/index.html"
-	router.Methods("GET").Path("/ui").
-		Handler(http.RedirectHandler("/ui/index.html", http.StatusMovedPermanently))
+// addFilesystemRoute creates a mux route to handle file system based GET requests.
+func (rs *routeStore) addFilesystemRoute(name, prefix, dir string) {
+	h := http.StripPrefix(prefix, http.FileServer(http.Dir(dir)))
+	//TODO enable authentication?
+	rs.muxRoutes.Name(name).Methods("GET", "HEAD").PathPrefix(prefix).Handler(h)
 }
 
 // getRouteMatchInfo returns routeMatchInfo from request context.