feat: add JWKS provider to the josev2 validator (#97)

Author: grounded042

.github/workflows/test.yaml

@@ -17,7 +17,7 @@ jobs:
       - name: install go
         uses: actions/setup-go@v1
         with:
-          go-version: 1.14
+          go-version: 1.16
       - name: checkout code
         uses: actions/checkout@v2
       - name: test

examples/http-example/main.go

@@ -20,7 +20,7 @@ var handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		fmt.Println(err)
 	}
 
-	fmt.Fprintf(w, "This is an authenticated request")
+	fmt.Fprintf(w, "This is an authenticated request\n")
 	fmt.Fprintf(w, "Claim content:\n")
 	fmt.Fprint(w, string(j))
 })

examples/http-jwks-example/README.md

@@ -0,0 +1,15 @@
+# HTTP JWKS example
+
+This is an example of how to use the http middleware with JWKS.
+
+# Using it
+
+To try this out:
+1. Install all dependencies with `go install`
+1. Go to https://manage.auth0.com/ and create a new API.
+1. Go to the "Test" tab of the API and copy the cURL example.
+1. Run the cURL example in your terminal and copy the `access_token` from the response. The tool jq can be helpful for this.
+1. In the example change `<your tenant domain>` on line 29 to the domain used in the cURL request.
+1. Run the example with `go run main.go`.
+1. In a new terminal use cURL to talk to the API: `curl -v --request GET --url http://localhost:3000`
+1. Now try it again with the `access_token` you copied earlier and run `curl -v --request GET --url http://localhost:3000 --header "authorization: Bearer $TOKEN"` to see a successful request.

examples/http-jwks-example/main.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+
+	jwtmiddleware "github.com/auth0/go-jwt-middleware"
+	"github.com/auth0/go-jwt-middleware/validate/josev2"
+	"gopkg.in/square/go-jose.v2"
+)
+
+var handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	user := r.Context().Value(jwtmiddleware.ContextKey{})
+	j, err := json.MarshalIndent(user, "", "\t")
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Println(err)
+	}
+
+	fmt.Fprintf(w, "This is an authenticated request\n")
+	fmt.Fprintf(w, "Claim content:\n")
+	fmt.Fprint(w, string(j))
+})
+
+func main() {
+	u, err := url.Parse("https://<your tenant domain>")
+	if err != nil {
+		// we'll panic in order to fail fast
+		panic(err)
+	}
+
+	p := josev2.NewCachingJWKSProvider(*u, 5*time.Minute)
+
+	// setup the piece which will validate tokens
+	validator, err := josev2.New(
+		p.KeyFunc,
+		jose.RS256,
+	)
+	if err != nil {
+		// we'll panic in order to fail fast
+		panic(err)
+	}
+
+	// setup the middleware
+	m := jwtmiddleware.New(validator.ValidateToken)
+
+	http.ListenAndServe("0.0.0.0:3000", m.CheckJWT(handler))
+}

go.mod

@@ -4,7 +4,7 @@ go 1.14
 
 require (
 	github.com/golang-jwt/jwt v3.2.1+incompatible
-	github.com/google/go-cmp v0.5.5
+	github.com/google/go-cmp v0.5.6
 	github.com/stretchr/testify v1.7.0 // indirect
 	golang.org/x/crypto v0.0.0-20210513164829-c07d793c2f9a // indirect
 	gopkg.in/square/go-jose.v2 v2.5.1

go.sum

@@ -4,6 +4,8 @@ github.com/golang-jwt/jwt v3.2.1+incompatible h1:73Z+4BJcrTC+KczS6WvTPvRGOp1WmfE
 github.com/golang-jwt/jwt v3.2.1+incompatible/go.mod h1:8pz2t5EyA70fFQQSrl6XZXzqecmYZeUEB8OUGHkxJ+I=
 github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

internal/oidc/oidc.go

@@ -0,0 +1,39 @@
+package oidc
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"path"
+)
+
+// WellKnownEndpoints holds the well known OIDC endpoints
+type WellKnownEndpoints struct {
+	JWKSURI string `json:"jwks_uri"`
+}
+
+// GetWellKnownEndpointsFromIssuerURL gets the well known endpoints for the
+// passed in issuer url
+func GetWellKnownEndpointsFromIssuerURL(ctx context.Context, issuerURL url.URL) (*WellKnownEndpoints, error) {
+	issuerURL.Path = path.Join(issuerURL.Path, ".well-known/openid-configuration")
+
+	req, err := http.NewRequest(http.MethodGet, issuerURL.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("could not build request to get well known endpoints: %w", err)
+	}
+	req = req.WithContext(ctx)
+
+	r, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("could not get well known endpoints from url %s: %w", issuerURL.String(), err)
+	}
+	var wkEndpoints WellKnownEndpoints
+	err = json.NewDecoder(r.Body).Decode(&wkEndpoints)
+	if err != nil {
+		return nil, fmt.Errorf("could not decode json body when getting well known endpoints: %w", err)
+	}
+
+	return &wkEndpoints, nil
+}

validate/josev2/examples/README.md

@@ -81,5 +81,7 @@ It will print out something like
 The token isn't valid: expected claims not validated: square/go-jose/jwt: validation failed, invalid issuer claim (iss)
 ```
 
+### JWKS
+For a JWKS example please see [examples/http-jwks-example/README.md](../../../examples/http-jwks-example/README.md).
 
 Take a look through the example code and things will make a lot more sense.

validate/josev2/josev2.go

@@ -2,10 +2,15 @@ package josev2
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"net/http"
+	"net/url"
+	"sync"
 	"time"
 
+	"github.com/auth0/go-jwt-middleware/internal/oidc"
 	"gopkg.in/square/go-jose.v2"
 	"gopkg.in/square/go-jose.v2/jwt"
 )
@@ -115,7 +120,7 @@ func (v *Validator) ValidateToken(ctx context.Context, token string) (interface{
 	// if jwt.ParseSigned did not error there will always be at least one
 	// header in the token
 	if signatureAlgorithm != "" && signatureAlgorithm != tok.Headers[0].Algorithm {
-		return nil, fmt.Errorf("expected %q signin algorithm but token specified %q", signatureAlgorithm, tok.Headers[0].Algorithm)
+		return nil, fmt.Errorf("expected %q signing algorithm but token specified %q", signatureAlgorithm, tok.Headers[0].Algorithm)
 	}
 
 	key, err := v.keyFunc(ctx)
@@ -133,7 +138,8 @@ func (v *Validator) ValidateToken(ctx context.Context, token string) (interface{
 	}
 
 	userCtx := &UserContext{
-		Claims: *claimDest[0].(*jwt.Claims),
+		CustomClaims: nil,
+		Claims:       *claimDest[0].(*jwt.Claims),
 	}
 
 	if err = userCtx.Claims.ValidateWithLeeway(v.expectedClaims(), v.allowedClockSkew); err != nil {
@@ -149,3 +155,112 @@ func (v *Validator) ValidateToken(ctx context.Context, token string) (interface{
 
 	return userCtx, nil
 }
+
+// JWKSProvider handles getting JWKS from the specified IssuerURL and exposes
+// KeyFunc which adheres to the keyFunc signature that the Validator requires.
+// Most likely you will want to use the CachingJWKSProvider as it handles
+// getting and caching JWKS which can help reduce request time and potential
+// rate limiting from your provider.
+type JWKSProvider struct {
+	IssuerURL url.URL
+}
+
+// NewJWKSProvider builds and returns a new JWKSProvider.
+func NewJWKSProvider(issuerURL url.URL) *JWKSProvider {
+	return &JWKSProvider{IssuerURL: issuerURL}
+}
+
+// KeyFunc adheres to the keyFunc signature that the Validator requires. While
+// it returns an interface to adhere to keyFunc, as long as the error is nil
+// the type will be *jose.JSONWebKeySet.
+func (p *JWKSProvider) KeyFunc(ctx context.Context) (interface{}, error) {
+	wkEndpoints, err := oidc.GetWellKnownEndpointsFromIssuerURL(ctx, p.IssuerURL)
+	if err != nil {
+		return nil, err
+	}
+
+	u, err := url.Parse(wkEndpoints.JWKSURI)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse JWKS URI from well known endpoints: %w", err)
+	}
+
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return nil, fmt.Errorf("could not build request to get JWKS: %w", err)
+	}
+	req = req.WithContext(ctx)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var jwks jose.JSONWebKeySet
+	if err := json.NewDecoder(resp.Body).Decode(&jwks); err != nil {
+		return nil, fmt.Errorf("could not decode jwks: %w", err)
+	}
+
+	return &jwks, nil
+}
+
+type cachedJWKS struct {
+	jwks      *jose.JSONWebKeySet
+	expiresAt time.Time
+}
+
+// CachingJWKSProvider handles getting JWKS from the specified IssuerURL and
+// caching them for CacheTTL time. It exposes KeyFunc which adheres to the
+// keyFunc signature that the Validator requires.
+type CachingJWKSProvider struct {
+	IssuerURL url.URL
+	CacheTTL  time.Duration
+
+	mu    sync.Mutex
+	cache map[string]cachedJWKS
+}
+
+// NewCachingJWKSProvider builds and returns a new CachingJWKSProvider. If
+// cacheTTL is zero then a default value of 1 minute will be used.
+func NewCachingJWKSProvider(issuerURL url.URL, cacheTTL time.Duration) *CachingJWKSProvider {
+	if cacheTTL == 0 {
+		cacheTTL = 1 * time.Minute
+	}
+
+	return &CachingJWKSProvider{
+		IssuerURL: issuerURL,
+		CacheTTL:  cacheTTL,
+		cache:     map[string]cachedJWKS{},
+	}
+}
+
+// KeyFunc adheres to the keyFunc signature that the Validator requires. While
+// it returns an interface to adhere to keyFunc, as long as the error is nil
+// the type will be *jose.JSONWebKeySet.
+func (c *CachingJWKSProvider) KeyFunc(ctx context.Context) (interface{}, error) {
+	issuer := c.IssuerURL.Hostname()
+
+	c.mu.Lock()
+	defer func() {
+		c.mu.Unlock()
+	}()
+
+	if cached, ok := c.cache[issuer]; ok {
+		if !time.Now().After(cached.expiresAt) {
+			return cached.jwks, nil
+		}
+	}
+
+	p := JWKSProvider{IssuerURL: c.IssuerURL}
+	jwks, err := p.KeyFunc(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	c.cache[issuer] = cachedJWKS{
+		jwks:      jwks.(*jose.JSONWebKeySet),
+		expiresAt: time.Now().Add(c.CacheTTL),
+	}
+
+	return jwks, nil
+}