AuthProxy: Fixes bug where long username could not be cached (#22926)

pkg/middleware/auth_proxy/auth_proxy.go

 package authproxy
 
 import (
-	"encoding/base32"
+	"encoding/hex"
 	"fmt"
+	"hash/fnv"
 	"net"
 	"net/mail"
 	"reflect"
@@ -146,6 +147,13 @@ func (auth *AuthProxy) IsAllowedIP() (bool, *Error) {
 	return false, newError("Proxy authentication required", err)
 }
 
+func HashCacheKey(key string) string {
+	hasher := fnv.New128a()
+	// according to the documentation, Hash.Write cannot error, but linter is complaining
+	hasher.Write([]byte(key)) // nolint: errcheck
+	return hex.EncodeToString(hasher.Sum(nil))
+}
+
 // getKey forms a key for the cache based on the headers received as part of the authentication flow.
 // Our configuration supports multiple headers. The main header contains the email or username.
 // And the additional ones that allow us to specify extra attributes: Name, Email or Groups.
@@ -156,7 +164,7 @@ func (auth *AuthProxy) getKey() string {
 		key = strings.Join([]string{key, header}, "-") // compose the key with any additional headers
 	})
 
-	hashedKey := base32.StdEncoding.EncodeToString([]byte(key))
+	hashedKey := HashCacheKey(key)
 	return fmt.Sprintf(CachePrefix, hashedKey)
 }
 

pkg/middleware/auth_proxy/auth_proxy_test.go

 package authproxy
 
 import (
-	"encoding/base32"
 	"errors"
 	"fmt"
 	"net/http"
@@ -79,7 +78,7 @@ func TestMiddlewareContext(t *testing.T) {
 
 			Convey("with a simple cache key", func() {
 				// Set cache key
-				key := fmt.Sprintf(CachePrefix, base32.StdEncoding.EncodeToString([]byte(name)))
+				key := fmt.Sprintf(CachePrefix, HashCacheKey(name))
 				err := store.Set(key, int64(33), 0)
 				So(err, ShouldBeNil)
 
@@ -88,7 +87,7 @@ func TestMiddlewareContext(t *testing.T) {
 				id, err := auth.Login()
 				So(err, ShouldBeNil)
 
-				So(auth.getKey(), ShouldEqual, "auth-proxy-sync-ttl:NVQXE23FNRXWO===")
+				So(auth.getKey(), ShouldEqual, "auth-proxy-sync-ttl:0a7f3374e9659b10980fd66247b0cf2f")
 				So(id, ShouldEqual, 33)
 			})
 
@@ -97,7 +96,7 @@ func TestMiddlewareContext(t *testing.T) {
 				group := "grafana-core-team"
 				req.Header.Add("X-WEBAUTH-GROUPS", group)
 
-				key := fmt.Sprintf(CachePrefix, base32.StdEncoding.EncodeToString([]byte(name+"-"+group)))
+				key := fmt.Sprintf(CachePrefix, HashCacheKey(name+"-"+group))
 				err := store.Set(key, int64(33), 0)
 				So(err, ShouldBeNil)
 
@@ -105,7 +104,7 @@ func TestMiddlewareContext(t *testing.T) {
 
 				id, err := auth.Login()
 				So(err, ShouldBeNil)
-				So(auth.getKey(), ShouldEqual, "auth-proxy-sync-ttl:NVQXE23FNRXWOLLHOJQWMYLOMEWWG33SMUWXIZLBNU======")
+				So(auth.getKey(), ShouldEqual, "auth-proxy-sync-ttl:14f69b7023baa0ac98c96b31cec07bc0")
 				So(id, ShouldEqual, 33)
 			})
 

pkg/middleware/middleware_test.go

@@ -2,7 +2,6 @@ package middleware
 
 import (
 	"context"
-	"encoding/base32"
 	"errors"
 	"fmt"
 	"net/http"
@@ -364,7 +363,7 @@ func TestMiddlewareContext(t *testing.T) {
 					return nil
 				})
 
-				key := fmt.Sprintf(authproxy.CachePrefix, base32.StdEncoding.EncodeToString([]byte(name+"-"+group)))
+				key := fmt.Sprintf(authproxy.CachePrefix, authproxy.HashCacheKey(name+"-"+group))
 				err := sc.remoteCacheService.Set(key, int64(33), 0)
 				So(err, ShouldBeNil)
 				sc.fakeReq("GET", "/")