fix: add tests for imdsv2

simples3.go

@@ -10,7 +10,6 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"encoding/xml"
-	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -23,10 +22,12 @@ import (
 )
 
 const (
-	imdsTokenURL           = "http://169.254.169.254/latest/api/token"
 	imdsTokenHeader        = "X-aws-ec2-metadata-token"
 	imdsTokenTtlHeader     = "X-aws-ec2-metadata-token-ttl-seconds"
-	securityCredentialsURL = "http://169.254.169.254/latest/meta-data/iam/security-credentials/"
+	metadataBaseURL        = "http://169.254.169.254/latest"
+	securityCredentialsURI = "/meta-data/iam/security-credentials/"
+	imdsTokenURI           = "/api/token"
+	defaultIMDSTokenTTL    = "60"
 
 	// AMZMetaPrefix to prefix metadata key.
 	AMZMetaPrefix = "x-amz-meta-"
@@ -150,19 +151,21 @@ func NewUsingIAM(region string) (*S3, error) {
 		&http.Client{
 			// Set a timeout of 3 seconds for AWS IAM Calls.
 			Timeout: time.Second * 3, //nolint:gomnd
-		}, securityCredentialsURL, region)
+		}, metadataBaseURL, region)
 }
 
 // fetchIMDSToken retrieves an IMDSv2 token from the
 // EC2 instance metadata service. It returns a token and boolean,
 // only if IMDSv2 is enabled in the EC2 instance metadata
 // configuration, otherwise returns an error.
-func fetchIMDSToken(cl *http.Client) (string, bool, error) {
+func fetchIMDSToken(cl *http.Client, baseURL string) (string, bool, error) {
-	req, err := http.NewRequest(http.MethodPut, imdsTokenURL, nil)
+	req, err := http.NewRequest(http.MethodPut, baseURL+imdsTokenURI, nil)
 	if err != nil {
 		return "", false, err
 	}
-	req.Header.Set(imdsTokenTtlHeader, "21600")
+
+	// Set the token TTL to 60 seconds.
+	req.Header.Set(imdsTokenTtlHeader, defaultIMDSTokenTTL)
 
 	resp, err := cl.Do(req)
 	if err != nil {
@@ -183,21 +186,22 @@ func fetchIMDSToken(cl *http.Client) (string, bool, error) {
 }
 
 // fetchIAMData fetches the IAM data from the given URL.
-// In case of a normal AWS setup, baseURL would be securityCredentialsURL.
+// In case of a normal AWS setup, baseURL would be metadataBaseURL.
 // You can use this method, to manually fetch IAM data from a custom
 // endpoint and pass it to SetIAMData.
 func fetchIAMData(cl *http.Client, baseURL string) (IAMResponse, error) {
-	var token string
+	token, useIMDSv2, err := fetchIMDSToken(cl, baseURL)
-	var useIMDSv2 bool
-	token, useIMDSv2, err := fetchIMDSToken(cl)
 	if err != nil {
-		return IAMResponse{}, fmt.Errorf("Error fetching IMDSv2 token: %w", err)
+		return IAMResponse{}, fmt.Errorf("error fetching IMDSv2 token: %w", err)
 	}
 
-	req, err := http.NewRequest(http.MethodGet, baseURL, nil)
+	url := baseURL + securityCredentialsURI
+
+	req, err := http.NewRequest(http.MethodGet, url, nil)
 	if err != nil {
-		return IAMResponse{}, err
+		return IAMResponse{}, fmt.Errorf("error creating imdsv2 token request: %w", err)
 	}
+
 	if useIMDSv2 {
 		req.Header.Set(imdsTokenHeader, token)
 	}
@@ -209,7 +213,7 @@ func fetchIAMData(cl *http.Client, baseURL string) (IAMResponse, error) {
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		return IAMResponse{}, fmt.Errorf("Error fetching IAM data: %s", resp.Status)
+		return IAMResponse{}, fmt.Errorf("error fetching IAM data: %s", resp.Status)
 	}
 
 	role, err := ioutil.ReadAll(resp.Body)
@@ -217,9 +221,9 @@ func fetchIAMData(cl *http.Client, baseURL string) (IAMResponse, error) {
 		return IAMResponse{}, err
 	}
 
-	req, err = http.NewRequest(http.MethodGet, baseURL+"/"+string(role), nil)
+	req, err = http.NewRequest(http.MethodGet, url+string(role), nil)
 	if err != nil {
-		return IAMResponse{}, err
+		return IAMResponse{}, fmt.Errorf("error creating role request: %w", err)
 	}
 	if useIMDSv2 {
 		req.Header.Set(imdsTokenHeader, token)
@@ -227,31 +231,32 @@ func fetchIAMData(cl *http.Client, baseURL string) (IAMResponse, error) {
 
 	resp, err = cl.Do(req)
 	if err != nil {
-		return IAMResponse{}, err
+		return IAMResponse{}, fmt.Errorf("error fetching role data: %w", err)
 	}
 	defer resp.Body.Close()
+
 	if resp.StatusCode != http.StatusOK {
-		return IAMResponse{}, errors.New(http.StatusText(resp.StatusCode))
+		return IAMResponse{}, fmt.Errorf("error fetching role data, got non 200 code: %s", resp.Status)
 	}
 
 	var jResp IAMResponse
 	jsonString, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return IAMResponse{}, err
+		return IAMResponse{}, fmt.Errorf("error reading role data: %w", err)
 	}
 
 	if err := json.Unmarshal(jsonString, &jResp); err != nil {
-		return IAMResponse{}, err
+		return IAMResponse{}, fmt.Errorf("error unmarshalling role data: %w (%s)", err, jsonString)
 	}
 
 	return jResp, nil
 }
 
-func newUsingIAM(cl *http.Client, credUrl, region string) (*S3, error) {
+func newUsingIAM(cl *http.Client, baseURL, region string) (*S3, error) {
 	// Get the IAM role
-	iamResp, err := fetchIAMData(cl, credUrl)
+	iamResp, err := fetchIAMData(cl, baseURL)
 	if err != nil {
-		return nil, fmt.Errorf("Error fetching IAM data: %w", err)
+		return nil, fmt.Errorf("error fetching IAM data: %w", err)
 	}
 
 	return &S3{
@@ -265,7 +270,7 @@ func newUsingIAM(cl *http.Client, credUrl, region string) (*S3, error) {
 }
 
 // setIAMData sets the IAM data on the S3 instance.
-func (s3 *S3) setIAMData(iamResp IAMResponse) {
+func (s3 *S3) SetIAMData(iamResp IAMResponse) {
 	s3.AccessKey = iamResp.AccessKeyID
 	s3.SecretKey = iamResp.SecretAccessKey
 	s3.Token = iamResp.Token

simples3_test.go

@@ -400,6 +400,7 @@ func TestS3_NewUsingIAM(t *testing.T) {
 				"Type" : "AWS-HMAC","AccessKeyId" : "abc",
 				"SecretAccessKey" : "abc","Token" : "abc",
 				"Expiration" : "2018-12-24T16:24:59Z"}`
+		respIMDSToken = `AQAEAJWopi8yvjKYXyWJbzESE0cms-OoTnptJzS3M9g5iNcl06UEkQ==`
 	)
 
 	tsFail := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -407,42 +408,88 @@ func TestS3_NewUsingIAM(t *testing.T) {
 	}))
 	defer tsFail.Close()
 
-	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	genServerHandlerFunc := func(failIMDS bool) http.HandlerFunc {
-		if r.Method != "GET" {
+		return func(w http.ResponseWriter, r *http.Request) {
-			t.Errorf("Expected 'GET' request, got '%s'", r.Method)
+			switch r.Method {
+			case "GET":
+				if !failIMDS {
+					// check if token is present
+					if r.Header.Get(imdsTokenHeader) == "" {
+						w.WriteHeader(http.StatusUnauthorized)
+						return
+					}
+				}
+
+				url := securityCredentialsURI
+				if r.URL.EscapedPath() == url {
+					w.WriteHeader(http.StatusOK)
+					io.WriteString(w, iam)
+				}
+				if r.URL.EscapedPath() == url+iam {
+					w.WriteHeader(http.StatusOK)
+					w.Header().Set("Content-Type", "application/json")
+					io.WriteString(w, resp)
+				}
+			case "PUT":
+				if failIMDS {
+					w.WriteHeader(http.StatusNotFound)
+					return
+				}
+
+				if r.URL.EscapedPath() == imdsTokenURI {
+					if r.Header.Get(imdsTokenTtlHeader) != "60" {
+						w.WriteHeader(http.StatusBadRequest)
+						return
+					}
+
+					w.WriteHeader(http.StatusOK)
+					io.WriteString(w, respIMDSToken)
+				}
+			default:
+				t.Errorf("Expected 'GET' or 'PUT' request, got '%s'", r.Method)
+			}
 		}
-		if r.URL.EscapedPath() == "/" {
+	}
-			w.WriteHeader(http.StatusOK)
+
-			io.WriteString(w, iam)
+	ts := httptest.NewServer(http.HandlerFunc(genServerHandlerFunc(false)))
-		}
-		if r.URL.EscapedPath() == "/"+iam {
-			w.WriteHeader(http.StatusOK)
-			w.Header().Set("Content-Type", "application/json")
-			io.WriteString(w, resp)
-		}
-	}))
 	defer ts.Close()
 
+	tsFailIMDS := httptest.NewServer(http.HandlerFunc(genServerHandlerFunc(true)))
+	defer tsFailIMDS.Close()
+
+	cl := &http.Client{Timeout: 1 * time.Second}
+
 	// Test for timeout.
-	_, err := newUsingIAM(&http.Client{Timeout: 1 * time.Second}, tsFail.URL, "abc")
+	_, err := newUsingIAM(cl, tsFail.URL, "abc")
 	if err == nil {
 		t.Errorf("Expected error, got nil")
 	} else {
 		var timeoutError net.Error
-		if errors.As(err, &timeoutError); !timeoutError.Timeout() {
+
+		if errors.As(err, &timeoutError) && !timeoutError.Timeout() {
 			t.Errorf("newUsingIAM() timeout check. got error = %v", err)
 		}
 	}
 
 	// Test for successful IAM fetch.
-	s3, err := newUsingIAM(http.DefaultClient, ts.URL, "abc")
+	s3, err := newUsingIAM(cl, ts.URL, "abc")
 	if err != nil {
 		t.Errorf("newUsingIAM() error = %v", err)
 	}
 
-	if s3.AccessKey != "abc" && s3.SecretKey != "abc" && s3.Region != "abc" {
+	if s3 == nil {
+		t.Errorf("newUsingIAM() got = %v", s3)
+	}
+
+	if s3.AccessKey != "abc" || s3.SecretKey != "abc" || s3.Region != "abc" {
 		t.Errorf("S3.FileDelete() got = %v", s3)
 	}
+
+	// Test for failed IMDS token fetch.
+	_, err = newUsingIAM(cl, tsFailIMDS.URL, "abc")
+	if err == nil {
+		t.Errorf("Expected error, got nil")
+	}
 }
 
 func TestCustomEndpoint(t *testing.T) {