aws/signer/v4: Add support for URL.EscapedPath to signer (#885)

Adds support for the URL.EscapedPath method added in Go1.5. This allows
you to hint to the signer and Go HTTP client what the escaped form of the
request's URI path will be. This is needed when using the AWS v4 Signer
outside of the context of the SDK on http.Requests you manage.

Also adds documentation to the signer that pre-escaping of the URI path
is needed, and suggestions how how to do this.

aws/signer/v4 TestStandaloneSign test function is an example
using the request signer outside of the SDK.

Fix #866

aws/signer/v4/functional_1_4_test.go

@@ -0,0 +1,40 @@
+// +build !go1.5
+
+package v4_test
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws/signer/v4"
+	"github.com/aws/aws-sdk-go/awstesting/unit"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStandaloneSign(t *testing.T) {
+	creds := unit.Session.Config.Credentials
+	signer := v4.NewSigner(creds)
+
+	for _, c := range standaloneSignCases {
+		host := fmt.Sprintf("%s.%s.%s.amazonaws.com",
+			c.SubDomain, c.Region, c.Service)
+
+		req, err := http.NewRequest("GET", fmt.Sprintf("https://%s", host), nil)
+		assert.NoError(t, err)
+
+		req.URL.Path = c.OrigURI
+		req.URL.RawQuery = c.OrigQuery
+		req.URL.Opaque = fmt.Sprintf("//%s%s", host, c.EscapedURI)
+		opaqueURI := req.URL.Opaque
+
+		_, err = signer.Sign(req, nil, c.Service, c.Region, time.Unix(0, 0))
+		assert.NoError(t, err)
+
+		actual := req.Header.Get("Authorization")
+		assert.Equal(t, c.ExpSig, actual)
+		assert.Equal(t, c.OrigURI, req.URL.Path)
+		assert.Equal(t, opaqueURI, req.URL.Opaque)
+	}
+}

aws/signer/v4/functional_1_5_test.go

@@ -0,0 +1,40 @@
+// +build go1.5
+
+package v4_test
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws/signer/v4"
+	"github.com/aws/aws-sdk-go/awstesting/unit"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestStandaloneSign(t *testing.T) {
+	creds := unit.Session.Config.Credentials
+	signer := v4.NewSigner(creds)
+
+	for _, c := range standaloneSignCases {
+		host := fmt.Sprintf("https://%s.%s.%s.amazonaws.com",
+			c.SubDomain, c.Region, c.Service)
+
+		req, err := http.NewRequest("GET", host, nil)
+		assert.NoError(t, err)
+
+		// URL.EscapedPath() will be used by the signer to get the
+		// escaped form of the request's URI path.
+		req.URL.Path = c.OrigURI
+		req.URL.RawQuery = c.OrigQuery
+
+		_, err = signer.Sign(req, nil, c.Service, c.Region, time.Unix(0, 0))
+		assert.NoError(t, err)
+
+		actual := req.Header.Get("Authorization")
+		assert.Equal(t, c.ExpSig, actual)
+		assert.Equal(t, c.OrigURI, req.URL.Path)
+		assert.Equal(t, c.EscapedURI, req.URL.EscapedPath())
+	}
+}

aws/signer/v4/functional_test.go

@@ -7,11 +7,28 @@ import (
 	"time"
 
 	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/signer/v4"
 	"github.com/aws/aws-sdk-go/awstesting/unit"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/stretchr/testify/assert"
 )
 
+var standaloneSignCases = []struct {
+	OrigURI                    string
+	OrigQuery                  string
+	Region, Service, SubDomain string
+	ExpSig                     string
+	EscapedURI                 string
+}{
+	{
+		OrigURI:   `/logs-*/_search`,
+		OrigQuery: `pretty=true`,
+		Region:    "us-west-2", Service: "es", SubDomain: "hostname-clusterkey",
+		EscapedURI: `/logs-%2A/_search`,
+		ExpSig:     `AWS4-HMAC-SHA256 Credential=AKID/19700101/us-west-2/es/aws4_request, SignedHeaders=host;x-amz-date;x-amz-security-token, Signature=79d0760751907af16f64a537c1242416dacf51204a7dd5284492d15577973b91`,
+	},
+}
+
 func TestPresignHandler(t *testing.T) {
 	svc := s3.New(unit.Session)
 	req, _ := svc.PutObjectRequest(&s3.PutObjectInput{
@@ -75,3 +92,25 @@ func TestPresignRequest(t *testing.T) {
 
 	assert.NotContains(t, urlstr, "+") // + encoded as %20
 }
+
+func TestStandaloneSign_CustomURIEscape(t *testing.T) {
+	var expectSig = `AWS4-HMAC-SHA256 Credential=AKID/19700101/us-east-1/es/aws4_request, SignedHeaders=host;x-amz-date;x-amz-security-token, Signature=6601e883cc6d23871fd6c2a394c5677ea2b8c82b04a6446786d64cd74f520967`
+
+	creds := unit.Session.Config.Credentials
+	signer := v4.NewSigner(creds, func(s *v4.Signer) {
+		s.DisableURIPathEscaping = true
+	})
+
+	host := "https://subdomain.us-east-1.es.amazonaws.com"
+	req, err := http.NewRequest("GET", host, nil)
+	assert.NoError(t, err)
+
+	req.URL.Path = `/log-*/_search`
+	req.URL.Opaque = "//subdomain.us-east-1.es.amazonaws.com/log-%2A/_search"
+
+	_, err = signer.Sign(req, nil, "es", "us-east-1", time.Unix(0, 0))
+	assert.NoError(t, err)
+
+	actual := req.Header.Get("Authorization")
+	assert.Equal(t, expectSig, actual)
+}

aws/signer/v4/uri_path.go

@@ -0,0 +1,24 @@
+// +build go1.5
+
+package v4
+
+import (
+	"net/url"
+	"strings"
+)
+
+func getURIPath(u *url.URL) string {
+	var uri string
+
+	if len(u.Opaque) > 0 {
+		uri = "/" + strings.Join(strings.Split(u.Opaque, "/")[3:], "/")
+	} else {
+		uri = u.EscapedPath()
+	}
+
+	if len(uri) == 0 {
+		uri = "/"
+	}
+
+	return uri
+}

aws/signer/v4/uri_path_1_4.go

@@ -0,0 +1,24 @@
+// +build !go1.5
+
+package v4
+
+import (
+	"net/url"
+	"strings"
+)
+
+func getURIPath(u *url.URL) string {
+	var uri string
+
+	if len(u.Opaque) > 0 {
+		uri = "/" + strings.Join(strings.Split(u.Opaque, "/")[3:], "/")
+	} else {
+		uri = u.Path
+	}
+
+	if len(uri) == 0 {
+		uri = "/"
+	}
+
+	return uri
+}

aws/signer/v4/v4.go

@@ -2,6 +2,48 @@
 //
 // Provides request signing for request that need to be signed with
 // AWS V4 Signatures.
+//
+// Standalone Signer
+//
+// Generally using the signer outside of the SDK should not require any additional
+// logic when using Go v1.5 or higher. The signer does this by taking advantage
+// of the URL.EscapedPath method. If your request URI requires additional escaping
+// you many need to use the URL.Opaque to define what the raw URI should be sent
+// to the service as.
+//
+// The signer will first check the URL.Opaque field, and use its value if set.
+// The signer does require the URL.Opaque field to be set in the form of:
+//
+//     "//<hostname>/<path>"
+//
+//     // e.g.
+//     "//example.com/some/path"
+//
+// The leading "//" and hostname are required or the URL.Opaque escaping will
+// not work correctly.
+//
+// If URL.Opaque is not set the signer will fallback to the URL.EscapedPath()
+// method and using the returned value. If you're using Go v1.4 you must set
+// URL.Opaque if the URI path needs escaping. If URL.Opaque is not set with
+// Go v1.5 the signer will fallback to URL.Path.
+//
+// AWS v4 signature validation requires that the canonical string's URI path
+// element must be the URI escaped form of the HTTP request's path.
+// http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
+//
+// The Go HTTP client will perform escaping automatically on the request. Some
+// of these escaping may cause signature validation errors because the HTTP
+// request differs from the URI path or query that the signature was generated.
+// https://golang.org/pkg/net/url/#URL.EscapedPath
+//
+// Because of this, it is recommended that when using the signer outside of the
+// SDK that explicitly escaping the request prior to being signed is preferable,
+// and will help prevent signature validation errors. This can be done by setting
+// the URL.Opaque or URL.RawPath. The SDK will use URL.Opaque first and then
+// call URL.EscapedPath() if Opaque is not set.
+//
+// Test `TestStandaloneSign` provides a complete example of using the signer
+// outside of the SDK and pre-escaping the URI path.
 package v4
 
 import (
@@ -120,6 +162,15 @@ type Signer struct {
 	// request's query string.
 	DisableHeaderHoisting bool
 
+	// Disables the automatic escaping of the URI path of the request for the
+	// siganture's canonical string's path. For services that do not need additional
+	// escaping then use this to disable the signer escaping the path.
+	//
+	// S3 is an example of a service that does not need additional escaping.
+	//
+	// http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
+	DisableURIPathEscaping bool
+
 	// currentTimeFn returns the time value which represents the current time.
 	// This value should only be used for testing. If it is nil the default
 	// time.Now will be used.
@@ -151,6 +202,8 @@ type signingCtx struct {
 	ExpireTime       time.Duration
 	SignedHeaderVals http.Header
 
+	DisableURIPathEscaping bool
+
 	credValues         credentials.Value
 	isPresign          bool
 	formattedTime      string
@@ -236,14 +289,15 @@ func (v4 Signer) signWithBody(r *http.Request, body io.ReadSeeker, service, regi
 	}
 
 	ctx := &signingCtx{
-		Request:     r,
-		Body:        body,
-		Query:       r.URL.Query(),
-		Time:        signTime,
-		ExpireTime:  exp,
-		isPresign:   exp != 0,
-		ServiceName: service,
-		Region:      region,
+		Request:                r,
+		Body:                   body,
+		Query:                  r.URL.Query(),
+		Time:                   signTime,
+		ExpireTime:             exp,
+		isPresign:              exp != 0,
+		ServiceName:            service,
+		Region:                 region,
+		DisableURIPathEscaping: v4.DisableURIPathEscaping,
 	}
 
 	if ctx.isRequestSigned() {
@@ -354,6 +408,10 @@ func signSDKRequestWithCurrTime(req *request.Request, curTimeFn func() time.Time
 		v4.Logger = req.Config.Logger
 		v4.DisableHeaderHoisting = req.NotHoist
 		v4.currentTimeFn = curTimeFn
+		if name == "s3" {
+			// S3 service should not have any escaping applied
+			v4.DisableURIPathEscaping = true
+		}
 	})
 
 	signingTime := req.Time
@@ -510,17 +568,10 @@ func (ctx *signingCtx) buildCanonicalHeaders(r rule, header http.Header) {
 
 func (ctx *signingCtx) buildCanonicalString() {
 	ctx.Request.URL.RawQuery = strings.Replace(ctx.Query.Encode(), "+", "%20", -1)
-	uri := ctx.Request.URL.Opaque
-	if uri != "" {
-		uri = "/" + strings.Join(strings.Split(uri, "/")[3:], "/")
-	} else {
-		uri = ctx.Request.URL.Path
-	}
-	if uri == "" {
-		uri = "/"
-	}
 
-	if ctx.ServiceName != "s3" {
+	uri := getURIPath(ctx.Request.URL)
+
+	if !ctx.DisableURIPathEscaping {
 		uri = rest.EscapePath(uri, false)
 	}
 

aws/signer/v4/v4_test.go

@@ -2,7 +2,6 @@ package v4
 
 import (
 	"bytes"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -217,7 +216,6 @@ func TestIgnorePreResignRequestWithValidCreds(t *testing.T) {
 	SignSDKRequest(r)
 	sig := r.HTTPRequest.URL.Query().Get("X-Amz-Signature")
 
-	fmt.Println(sig)
 	signSDKRequestWithCurrTime(r, func() time.Time {
 		// Simulate one second has passed so that signature's date changes
 		// when it is resigned.