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Make codecs lookup optional for HTTP methods that cannot contain requ… #27

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96 changes: 88 additions & 8 deletions codec.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,14 +4,19 @@ import (
"context"
"fmt"
"net/http"
"strconv"
"strings"

"github.com/tiny-go/codec"
"github.com/tiny-go/errors"
)

const (
acceptHeader = "Accept"
contentTypeHeader = "Content-Type"
acceptHeader = "Accept"
contentTypeHeader = "Content-Type"
contentLengthHeader = "Content-Length"
transferEncodingHeader = "Transfer-Encoding"
defaultTransferEncoding = "identity"
)

// codecKey is a private unique key that is used to put/get codec from the context.
Expand All @@ -35,16 +40,22 @@ func Codec(fn errors.HandlerFunc, codecs Codecs) Middleware {
var reqCodec, resCodec codec.Codec
// get request codec
if reqCodec = codecs.Lookup(r.Header.Get(contentTypeHeader)); reqCodec == nil {
fn(w, fmt.Sprintf("unsupported request codec: %q", r.Header.Get(contentTypeHeader)), http.StatusBadRequest)
return
if isContentTypeHeaderRequired(r) {
fn(w, fmt.Sprintf("unsupported request codec: %q", r.Header.Get(contentTypeHeader)), http.StatusBadRequest)
return
}
} else {
r = r.WithContext(context.WithValue(r.Context(), codecKey{"req"}, reqCodec))
}
r = r.WithContext(context.WithValue(r.Context(), codecKey{"req"}, reqCodec))
// get response codec
if resCodec = codecs.Lookup(r.Header.Get(acceptHeader)); resCodec == nil {
fn(w, fmt.Sprintf("unsupported response codec: %q", r.Header.Get(acceptHeader)), http.StatusBadRequest)
return
if isAcceptHeaderRequired(r) {
fn(w, fmt.Sprintf("unsupported response codec: %q", r.Header.Get(acceptHeader)), http.StatusBadRequest)
return
}
} else {
r = r.WithContext(context.WithValue(r.Context(), codecKey{"res"}, resCodec))
}
r = r.WithContext(context.WithValue(r.Context(), codecKey{"res"}, resCodec))
// call the next handler
next.ServeHTTP(w, r)
})
Expand All @@ -62,3 +73,72 @@ func ResponseCodecFromContext(ctx context.Context) codec.Codec {
codec, _ := ctx.Value(codecKey{"res"}).(codec.Codec)
return codec
}

// isContentTypeHeaderRequired returns the HTTP method request body type requirement.
// By RFC7231 (https://tools.ietf.org/html/rfc7231) only POST, PUT and PATCH methods
// should contain a request body. DELETE method body is optional.
func isContentTypeHeaderRequired(r *http.Request) bool {
switch r.Method {
// Body is required
case http.MethodPost: fallthrough
case http.MethodPut: fallthrough
case http.MethodPatch:
return shouldRequestBodyBeProcessed(r, true)
// May have body, but not required
case http.MethodDelete:
return shouldRequestBodyBeProcessed(r, false)
// No body
case http.MethodGet: fallthrough
case http.MethodHead: fallthrough
case http.MethodConnect: fallthrough
case http.MethodOptions: fallthrough
case http.MethodTrace: fallthrough
default:
return false
}
}

// isAcceptHeaderRequired returns the HTTP method response body type requirement.
// By RFC7231 (https://tools.ietf.org/html/rfc7231) only GET, POST, CONNECT,
// OPTIONS and PATCH methods should indicate the details of a response body.
// DELETE method response body is optional.
func isAcceptHeaderRequired(r *http.Request) bool {
switch r.Method {
// Body is required
case http.MethodGet: fallthrough
case http.MethodPost: fallthrough
case http.MethodConnect: fallthrough
case http.MethodOptions: fallthrough
case http.MethodPatch:
return true
// May have body, but not required
case http.MethodDelete: fallthrough
// No body
case http.MethodHead: fallthrough
case http.MethodPut: fallthrough
case http.MethodTrace: fallthrough
default:
return false
}
}

func shouldRequestBodyBeProcessed(r *http.Request, required bool) bool {
transferEncoding := r.Header.Get(transferEncodingHeader)
hasRequestBody := transferEncoding != "" && !strings.EqualFold(transferEncoding, defaultTransferEncoding)

hasRequestBody = hasRequestBody || func() bool {
contentLengthStr := r.Header.Get(contentLengthHeader)
if contentLengthStr != "" {
contentLength, err := strconv.Atoi(contentLengthStr)
if err != nil || contentLength < 0 {
return false
}

return contentLength > 0
}

return required
}()

return hasRequestBody
}
86 changes: 80 additions & 6 deletions codec_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,45 +21,119 @@ func TestCodecFromList(t *testing.T) {
body string
}

type Data struct {
Test string
}

cases := []testCase{
{
title: "should throw an error if request codec in not supported",
title: "should throw an error if a request codec is required but not supported",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(nil),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodGet, "", nil)
r, _ := http.NewRequest(http.MethodPost, "", nil)
r.Header.Set(contentTypeHeader, "unknown")
r.Header.Set(contentLengthHeader, "1")
return r
}(),
code: http.StatusBadRequest,
body: "unsupported request codec: \"unknown\"\n",
},
{
title: "should throw an error if response codec in not supported",
title: "should ignore a request codec if not supported but not required",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("passed"))
}),
),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodDelete, "", nil)
r.Header.Set(contentTypeHeader, "unknown")
return r
}(),
code: http.StatusOK,
body: "passed",
},
{
title: "should use a request codec if supported but not required",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(
BodyClose(
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
var data Data
RequestCodecFromContext(r.Context()).Decoder(r.Body).Decode(&data)
w.Write([]byte(data.Test))
}),
),
),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodDelete, "", strings.NewReader("{\"test\":\"passed\"}\n"))
r.Header.Set(contentTypeHeader, "application/json")
r.Header.Set(contentLengthHeader, "1")
return r
}(),
code: http.StatusOK,
body: "passed",
},
{
title: "should throw an error if response codec is required but not supported",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(nil),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodGet, "", nil)
r, _ := http.NewRequest(http.MethodPost, "", nil)
r.Header.Set(contentTypeHeader, "application/json")
r.Header.Set(contentLengthHeader, "0")
r.Header.Set(acceptHeader, "unknown")
return r
}(),
code: http.StatusBadRequest,
body: "unsupported response codec: \"unknown\"\n",
},
{
title: "should ignore a response codec if not supported but not required",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("passed"))
}),
),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodDelete, "", nil)
r.Header.Set(acceptHeader, "unknown")
return r
}(),
code: http.StatusOK,
body: "passed",
},
{
title: "should use a response codec if supported but not required",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
data := Data{
Test: "passed",
}
ResponseCodecFromContext(r.Context()).Encoder(w).Encode(data)
}),
),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodDelete, "", nil)
r.Header.Set(acceptHeader, "application/xml")
return r
}(),
code: http.StatusOK,
body: "<Data><Test>passed</Test></Data>",
},
{
title: "should find corresponding codecs and handle the request successfully",
handler: Codec(nil, driver.DummyRegistry{&json.JSON{}, &xml.XML{}})(
BodyClose(
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
type Data struct{ Test string }
var data Data
RequestCodecFromContext(r.Context()).Decoder(r.Body).Decode(&data)
ResponseCodecFromContext(r.Context()).Encoder(w).Encode(data)
}),
),
),
request: func() *http.Request {
r, _ := http.NewRequest(http.MethodGet, "", strings.NewReader("{\"test\":\"passed\"}\n"))
r, _ := http.NewRequest(http.MethodPost, "", strings.NewReader("{\"test\":\"passed\"}\n"))
r.Header.Set(contentTypeHeader, "application/json")
r.Header.Set(contentLengthHeader, "1")
r.Header.Set(acceptHeader, "application/xml")
return r
}(),
Expand Down