fix: allow spaces in Authorization string

This change removes all spaces after the algorithm to have
standard parsing for the following key/value pairs. This fixes
some clients that were using a slightly different format than
the example AWS request strings.

s3api/utils/auth-reader.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"strings"
 	"time"
+	"unicode"
 
 	"github.com/aws/aws-sdk-go-v2/aws"
 	v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
@@ -173,18 +174,20 @@ func ParseAuthorization(authorization string) (AuthData, error) {
 	// authorization must start with:
 	// Authorization: <ALGORITHM>
 	// followed by key=value pairs separated by ","
-	authParts := strings.Fields(authorization)
+	authParts := strings.SplitN(authorization, " ", 2)
 	for i, el := range authParts {
-		authParts[i] = strings.TrimSpace(el)
+		if strings.Contains(el, " ") {
+			authParts[i] = removeSpace(el)
+		}
 	}
 
-	if len(authParts) < 3 {
+	if len(authParts) < 2 {
 		return a, s3err.GetAPIError(s3err.ErrMissingFields)
 	}
 
 	algo := authParts[0]
 
-	kvData := strings.Join(authParts[1:], "")
+	kvData := authParts[1]
 	kvPairs := strings.Split(kvData, ",")
 	// we are expecting at least Credential, SignedHeaders, and Signature
 	// key value pairs here
@@ -244,6 +247,17 @@ func ParseAuthorization(authorization string) (AuthData, error) {
 	}, nil
 }
 
+func removeSpace(str string) string {
+	var b strings.Builder
+	b.Grow(len(str))
+	for _, ch := range str {
+		if !unicode.IsSpace(ch) {
+			b.WriteRune(ch)
+		}
+	}
+	return b.String()
+}
+
 var (
 	specialValues = map[string]bool{
 		"UNSIGNED-PAYLOAD":                                 true,

s3api/utils/auth_test.go

@@ -0,0 +1,40 @@
+package utils
+
+import (
+	"testing"
+)
+
+func TestAuthParse(t *testing.T) {
+	vectors := []struct {
+		name    string // name of test string
+		authstr string // Authorization string
+		algo    string
+		sig     string
+	}{{
+		name:    "restic",
+		authstr: "AWS4-HMAC-SHA256 Credential=user/20240116/us-east-1/s3/aws4_request,SignedHeaders=content-md5;host;x-amz-content-sha256;x-amz-date;x-amz-decoded-content-length,Signature=d5199fc7f3aa35dd3d400427be2ae4c98bfad390785280cbb9eea015b51e12ac",
+		algo:    "AWS4-HMAC-SHA256",
+		sig:     "d5199fc7f3aa35dd3d400427be2ae4c98bfad390785280cbb9eea015b51e12ac",
+	},
+		{
+			name:    "aws eaxample",
+			authstr: "AWS4-HMAC-SHA256 Credential=AKIAIOSFODNN7EXAMPLE/20130524/us-east-1/s3/aws4_request, SignedHeaders=host;range;x-amz-date, Signature=fe5f80f77d5fa3beca038a248ff027d0445342fe2855ddc963176630326f1024",
+			algo:    "AWS4-HMAC-SHA256",
+			sig:     "fe5f80f77d5fa3beca038a248ff027d0445342fe2855ddc963176630326f1024",
+		}}
+
+	for _, v := range vectors {
+		t.Run(v.name, func(t *testing.T) {
+			data, err := ParseAuthorization(v.authstr)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if data.Algorithm != v.algo {
+				t.Errorf("algo got %v, expected %v", data.Algorithm, v.algo)
+			}
+			if data.Signature != v.sig {
+				t.Errorf("signature got %v, expected %v", data.Signature, v.sig)
+			}
+		})
+	}
+}