Merge pull request #22 from aws/fix/RolesAnywhere-3788

RolesAnywhere-3788: Include token TTL header in token API response

Author: 13ajay

Makefile

@@ -1,4 +1,4 @@
-VERSION=1.0.3
+VERSION=1.0.4
 
 release:
 	go build -buildmode=pie -ldflags "-X 'main.Version=${VERSION}' -linkmode=external -w -s" -trimpath -o build/bin/aws_signing_helper cmd/aws_signing_helper/main.go

aws_signing_helper/serve.go

@@ -28,7 +28,10 @@ type RefreshableCred struct {
 	AccessKeyId     string
 	SecretAccessKey string
 	Token           string
+	Code            string
+	Type            string
 	Expiration      time.Time
+	LastUpdated     time.Time
 }
 
 type Endpoint struct {
@@ -50,6 +53,9 @@ const DEFAULT_TOKEN_TTL_SECONDS = "21600"
 
 const X_FORWARDED_FOR_HEADER = "X-Forwarded-For"
 
+const REFRESHABLE_CRED_TYPE = "AWS-HMAC"
+const REFRESHABLE_CRED_CODE = "Success"
+
 const MAX_TOKENS = 256
 
 var mutex sync.Mutex
@@ -120,6 +126,27 @@ func CheckValidToken(w http.ResponseWriter, r *http.Request) error {
 	return nil
 }
 
+// Helper function that finds a token's TTL in seconds
+func FindTokenTTLSeconds(r *http.Request) (string, error) {
+	token := r.Header.Get(EC2_METADATA_TOKEN_HEADER)
+	if token == "" {
+		msg := "no token provided"
+		return "", errors.New(msg)
+	}
+
+	mutex.Lock()
+	expiration, ok := tokenMap[token]
+	mutex.Unlock()
+	if ok {
+		tokenTTLFloat := expiration.Sub(time.Now()).Seconds()
+		tokenTTLInt64 := int64(tokenTTLFloat)
+		return strconv.FormatInt(tokenTTLInt64, 10), nil
+	} else {
+		msg := "invalid token provided"
+		return "", errors.New(msg)
+	}
+}
+
 func AllIssuesHandlers(cred *RefreshableCred, roleName string, opts *CredentialsOpts) (http.HandlerFunc, http.HandlerFunc, http.HandlerFunc) {
 	// Handles PUT requests to /latest/api/token/
 	putTokenHandler := func(w http.ResponseWriter, r *http.Request) {
@@ -158,6 +185,7 @@ func AllIssuesHandlers(cred *RefreshableCred, roleName string, opts *Credentials
 		expirationTime := time.Now().Add(time.Second * time.Duration(tokenTTL))
 		InsertToken(token, expirationTime)
 
+		w.Header().Set(EC2_METADATA_TOKEN_TTL_HEADER, tokenTTLStr)
 		io.WriteString(w, token) // nosemgrep
 	}
 
@@ -173,6 +201,12 @@ func AllIssuesHandlers(cred *RefreshableCred, roleName string, opts *Credentials
 			return
 		}
 
+		tokenTTL, err := FindTokenTTLSeconds(r)
+		if err != nil {
+			w.WriteHeader(http.StatusUnauthorized)
+			return
+		}
+		w.Header().Set(EC2_METADATA_TOKEN_TTL_HEADER, tokenTTL)
 		io.WriteString(w, roleName) // nosemgrep
 	}
 
@@ -195,7 +229,11 @@ func AllIssuesHandlers(cred *RefreshableCred, roleName string, opts *Credentials
 			cred.SecretAccessKey = credentialProcessOutput.SecretAccessKey
 			cred.Token = credentialProcessOutput.SessionToken
 			cred.Expiration, _ = time.Parse(time.RFC3339, credentialProcessOutput.Expiration)
+			cred.Code = REFRESHABLE_CRED_CODE
+			cred.LastUpdated = time.Now()
+			cred.Type = REFRESHABLE_CRED_TYPE
 			err := json.NewEncoder(w).Encode(cred)
+
 			if err != nil {
 				w.WriteHeader(http.StatusInternalServerError)
 				io.WriteString(w, "failed to encode credentials")
@@ -209,6 +247,13 @@ func AllIssuesHandlers(cred *RefreshableCred, roleName string, opts *Credentials
 				return
 			}
 		}
+
+		tokenTTL, err := FindTokenTTLSeconds(r)
+		if err != nil {
+			w.WriteHeader(http.StatusUnauthorized)
+			return
+		}
+		w.Header().Set(EC2_METADATA_TOKEN_TTL_HEADER, tokenTTL)
 	}
 
 	return putTokenHandler, getRoleNameHandler, getCredentialsHandler
@@ -228,6 +273,9 @@ func Serve(port int, credentialsOptions CredentialsOpts) {
 	refreshableCred.SecretAccessKey = credentialProcessOutput.SecretAccessKey
 	refreshableCred.Token = credentialProcessOutput.SessionToken
 	refreshableCred.Expiration, _ = time.Parse(time.RFC3339, credentialProcessOutput.Expiration)
+	refreshableCred.Code = REFRESHABLE_CRED_CODE
+	refreshableCred.LastUpdated = time.Now()
+	refreshableCred.Type = REFRESHABLE_CRED_TYPE
 	endpoint := &Endpoint{PortNum: port, TmpCred: refreshableCred}
 	endpoint.Server = &http.Server{}
 	roleResourceParts := strings.Split(roleArn.Resource, "/")