global desc lookup

Author: Marc Odermatt

scion/cmd/scion/fabrid.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 	"net"
+	"strconv"
 	"time"
 
 	"github.com/scionproto/scion/pkg/addr"
@@ -46,7 +47,7 @@ func newFabrid(pather CommandPather) *cobra.Command {
 	var cmd = &cobra.Command{
 		Use:   "fabrid",
 		Short: "Display FABRID policy information",
-		Args:  cobra.ExactArgs(1),
+		Args:  cobra.RangeArgs(1, 2),
 		Example: fmt.Sprintf(`  %[1]s showpaths 1-ff00:0:110 --extended
   %[1]s showpaths 1-ff00:0:110 --local 127.0.0.55 --json
   %[1]s showpaths 1-ff00:0:111 --sequence="0-0#2 0*" # outgoing IfID=2
@@ -56,10 +57,6 @@ func newFabrid(pather CommandPather) *cobra.Command {
 		Long: `'fabrid' lists available policies at a remote AS, or shows the
 description of a specific policy.`,
 		RunE: func(cmd *cobra.Command, args []string) error {
-			dst, err := addr.ParseIA(args[0])
-			if err != nil {
-				return serrors.WrapStr("invalid destination ISD-AS", err)
-			}
 			if err := app.SetupLog(flags.logLevel); err != nil {
 				return serrors.WrapStr("setting up logging", err)
 			}
@@ -87,16 +84,35 @@ description of a specific policy.`,
 			)
 
 			span, traceCtx := tracing.CtxWith(context.Background(), "run")
-			span.SetTag("dst.isd_as", dst)
 			defer span.Finish()
 
 			ctx, cancel := context.WithTimeout(traceCtx, flags.timeout)
 			defer cancel()
-			res, err := fabrid.Run(ctx, dst, flags.cfg)
-			if err != nil {
-				return err
+			if len(args) == 1 {
+				identifier, err := strconv.ParseUint(args[0], 10, 32)
+				if err != nil {
+					return serrors.WrapStr("invalid policy  identifier", err)
+				}
+				_, err = fabrid.Run(ctx, nil, uint32(identifier), flags.cfg)
+				if err != nil {
+					return err
+				}
+
+			} else if len(args) == 2 {
+				dst, err := addr.ParseIA(args[0])
+				if err != nil {
+					return serrors.WrapStr("invalid destination ISD-AS", err)
+				}
+				identifier, err := strconv.ParseUint(args[1], 10, 32)
+				if err != nil {
+					return serrors.WrapStr("invalid policy  identifier", err)
+				}
+				_, err = fabrid.Run(ctx, &dst, uint32(identifier), flags.cfg)
+				if err != nil {
+					return err
+				}
+				span.SetTag("dst.isd_as", dst)
 			}
-			fmt.Println(res.Destination, res.Description)
 			switch flags.format {
 			case "human":
 				return nil

scion/fabrid/fabrid.go

@@ -16,30 +16,92 @@ package fabrid
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"github.com/scionproto/scion/pkg/addr"
 	"github.com/scionproto/scion/pkg/daemon"
 	"github.com/scionproto/scion/pkg/private/serrors"
+	"io/ioutil"
+	"net/http"
 )
 
 // Result contains all the discovered paths.
 type Result struct {
-	Destination addr.IA `json:"destination" yaml:"destination"`
-	Description string  `json:"description,omitempty" yaml:"description,omitempty"`
+	Destination *addr.IA `json:"destination" yaml:"destination"`
+	Description string   `json:"description,omitempty" yaml:"description,omitempty"`
 }
 
 // Run lists information for FABRID policies to stdout.
-func Run(ctx context.Context, dst addr.IA, cfg Config) (*Result, error) {
-	sdConn, err := daemon.NewService(cfg.Daemon).Connect(ctx)
+func Run(ctx context.Context, dst *addr.IA, identifier uint32, cfg Config) (*Result, error) {
+	var description string
+	if dst != nil {
+		sdConn, err := daemon.NewService(cfg.Daemon).Connect(ctx)
+		if err != nil {
+			return nil, serrors.WrapStr("connecting to the SCION Daemon", err, "addr", cfg.Daemon)
+		}
+		defer sdConn.Close()
+
+		description, err = sdConn.RemotePolicyDescription(ctx, identifier, *dst)
+		if err != nil {
+			return nil, serrors.WrapStr("retrieving description from the SCION Daemon", err)
+		}
+	} else {
+		// Replace with the raw URL of your GitHub content (e.g., https://raw.githubusercontent.com/user/repo/branch/path/to/policies.json)
+		globalPolicyURL := "https://raw.githubusercontent.com/marcodermatt/fabrid-global-policies/main/policy-descriptions.json"
+
+		// Fetch the global policy from the URL
+		policy, err := FetchGlobalPolicy(globalPolicyURL)
+		if err != nil {
+			return nil, serrors.WrapStr("fetching global policy", err)
+		}
+
+		// Retrieve the description for the given identifier
+		description, err = GetPolicyDescription(policy, identifier)
+		if err != nil {
+			return nil, serrors.WrapStr("getting global policy description", err)
+		}
+
+	}
+	// Output the description
+	fmt.Printf("Policy %d: %s\n", identifier, description)
+	return &Result{Destination: dst, Description: description}, nil
+}
+
+// GlobalPolicy holds the mapping of uint32 identifiers to their string descriptions
+type GlobalPolicy map[uint32]string
+
+// FetchGlobalPolicy fetches and parses the global policy from the given URL
+func FetchGlobalPolicy(url string) (GlobalPolicy, error) {
+	resp, err := http.Get(url)
 	if err != nil {
-		return nil, serrors.WrapStr("connecting to the SCION Daemon", err, "addr", cfg.Daemon)
+		return nil, serrors.WrapStr("failed to fetch global policy", err)
 	}
-	defer sdConn.Close()
+	defer resp.Body.Close()
 
-	description, err := sdConn.RemotePolicyDescription(ctx, 10, dst)
+	if resp.StatusCode != http.StatusOK {
+		return nil, serrors.New("failed to fetch global policy", "StatusCode", resp.StatusCode)
+	}
+
+	// Read the response body
+	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return nil, serrors.WrapStr("retrieving description from the SCION Daemon", err)
+		return nil, serrors.WrapStr("failed to read response body", err)
 	}
-	fmt.Println(description)
-	return &Result{Destination: dst, Description: description}, nil
+
+	// Unmarshal the JSON data into a map
+	var policy GlobalPolicy
+	if err = json.Unmarshal(body, &policy); err != nil {
+		return nil, serrors.WrapStr("failed to unmarshal policy JSON", err)
+	}
+
+	return policy, nil
+}
+
+// GetPolicyDescription retrieves the description for the given identifier
+func GetPolicyDescription(policy GlobalPolicy, identifier uint32) (string, error) {
+	description, exists := policy[identifier]
+	if !exists {
+		return "", serrors.New("no policy found", "identifier", identifier)
+	}
+	return description, nil
 }