ParseContentType now returns a blank media type if the input is blank or malformed

Author: rickb777

header/contenttype.go

@@ -20,6 +20,14 @@ type ContentType struct {
 	Params []KV
 }
 
+// WithDefault returns "*/*" if ct has a blank media type.
+func (ct ContentType) WithDefault() ContentType {
+	if ct.MediaType == "" {
+		ct.MediaType = "*/*"
+	}
+	return ct
+}
+
 func (ct ContentType) Split() (string, string) {
 	t, s, _ := strings.Cut(ct.MediaType, "/")
 	return t, s
@@ -99,27 +107,26 @@ func (ct ContentType) String() string {
 	return buf.String()
 }
 
-var starStar = ContentType{MediaType: "*/*"}
-
 // ParseContentTypeFromHeaders gets the "Content-Type" header and returns
-// its parsed value.
+// its parsed value. An absent or malformed input yields a blank media type.
 func ParseContentTypeFromHeaders(hdrs http.Header) ContentType {
 	cts := hdrs[headername.ContentType]
 	if len(cts) == 0 {
-		return starStar
+		return ContentType{}
 	}
 	return ParseContentType(cts[0])
 }
 
 // ParseContentType parses a content type value.
+// An absent or malformed input yields a blank media type.
 func ParseContentType(ct string) ContentType {
 	if ct == "" {
-		return starStar
+		return ContentType{}
 	}
 
 	mt, params, err := mime.ParseMediaType(ct)
 	if err != nil {
-		return starStar
+		return ContentType{}
 	}
 
 	var paramsKV []KV

header/contenttype_test.go

@@ -14,7 +14,8 @@ func TestParseContentTypeFromHeaders(t *testing.T) {
 
 	ct1 := ParseContentTypeFromHeaders(hdrs)
 
-	expect.Any(ct1).ToBe(t, ContentType{MediaType: "*/*"})
+	expect.Any(ct1).ToBe(t, ContentType{MediaType: ""})
+	expect.Any(ct1.WithDefault()).ToBe(t, ContentType{MediaType: "*/*"})
 
 	hdrs.Set(headername.ContentType, "text/plain")
 
@@ -25,16 +26,16 @@ func TestParseContentTypeFromHeaders(t *testing.T) {
 
 func TestParseContentType(t *testing.T) {
 	// blank value is treated as star-star
-	expect.Any(ParseContentType("")).ToBe(t, ContentType{MediaType: "*/*"})
+	expect.Any(ParseContentType("")).ToBe(t, ContentType{MediaType: ""})
 
 	// illegal value is treated as star-star
-	expect.Any(ParseContentType("/")).ToBe(t, ContentType{MediaType: "*/*"})
+	expect.Any(ParseContentType("/")).ToBe(t, ContentType{MediaType: ""})
 
 	// illegal value is treated as star-star
-	expect.Any(ParseContentType("/plain")).ToBe(t, ContentType{MediaType: "*/*"})
+	expect.Any(ParseContentType("/plain")).ToBe(t, ContentType{MediaType: ""})
 
 	// error case handled silently
-	expect.Any(ParseContentType("text/")).ToBe(t, ContentType{MediaType: "*/*"})
+	expect.Any(ParseContentType("text/")).ToBe(t, ContentType{MediaType: ""})
 
 	expect.Any(ParseContentType("text/plain")).ToBe(t, ContentType{MediaType: "text/plain"})
 

magefiles/build.go

@@ -6,9 +6,10 @@
 package main
 
 import (
-	"github.com/magefile/mage/sh"
 	"log"
 	"os"
+
+	"github.com/magefile/mage/sh"
 )
 
 var Default = Build

offer/offer.go

@@ -51,7 +51,7 @@ type Offer struct {
 // The correct behaviour is a 406 when no match can be made.
 func Of(processor Processor, contentType string) Offer {
 	return Offer{
-		ContentType: header.ParseContentType(contentType),
+		ContentType: header.ParseContentType(contentType).WithDefault(),
 		processor:   processor,
 		Langs:       []string{"*"},
 		data:        make(map[string]datapkg.Data),