first Multipart approach

http/httphi/bench_test.go

@@ -4,6 +4,7 @@ import (
 	"io"
 	"testing"
 
+	"github.com/soypat/lneto/http/httpraw"
 	"github.com/soypat/lneto/internal"
 )
 
@@ -95,3 +96,34 @@ func BenchmarkHandle(b *testing.B) {
 		})
 	}
 }
+
+// benchForm is package level so the Form's pair slice is reused across requests,
+// as a real handler holding one per goroutine would.
+var benchForm httpraw.Form
+
+// BenchmarkRequestParseForm measures reading and parsing a urlencoded body into
+// a buffer the caller owns. Nothing on the path may allocate.
+func BenchmarkRequestParseForm(b *testing.B) {
+	const request = "POST /f HTTP/1.1\r\nHost: tinygo.org\r\n" +
+		"Content-Type: application/x-www-form-urlencoded\r\nContent-Length: 27\r\n\r\n" +
+		"user=gopher&msg=hello+world"
+	buf := make([]byte, 64)
+	var mux MuxSlice
+	mux.Handle("POST /f", func(ex *Exchange) {
+		err := ex.RequestParseForm(&benchForm, buf, nopBackoff)
+		if err != nil || benchForm.Len() != 2 {
+			panic("invalid result")
+		}
+	})
+	conn := &benchConn{request: request}
+	exch := benchExchange(b, conn)
+	b.ReportAllocs()
+	b.SetBytes(int64(len(request)))
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		conn.rewind()
+		exch.Release()
+		exch.Acquire(conn)
+		Handle(exch, &mux, nopBackoff)
+	}
+}

http/httphi/exchange.go

@@ -380,6 +380,122 @@ func (exch *Exchange) RequestParseCookie(dst *httpraw.Cookie, key string) error
 	return dst.ParseBytes(value)
 }
 
+// RequestContentType returns the request's Content-Type field value as it
+// appears on the wire, parameters included, nil if absent. Test it with
+// [httpraw.MediaTypeIs] and pick parameters out with [httpraw.ContentParam].
+func (exch *Exchange) RequestContentType() []byte {
+	return exch.RequestHeader("Content-Type")
+}
+
+// RequestContentLength returns the body length declared by the request's
+// Content-Length field. An absent field is not a client error: such a request
+// has no body at all, RFC 9112 6.3. Check for the error to answer 411 instead.
+// See [httpraw.Header.ContentLength].
+func (exch *Exchange) RequestContentLength() (int64, error) {
+	return exch.RequestHeaderRaw().ContentLength()
+}
+
+// RequestParseForm reads the request body into buf and parses it as
+// "application/x-www-form-urlencoded" into dst. buf is the only storage used and
+// the only limit: a body longer than buf is refused with [lneto.ErrBufferFull]
+// before a single byte is read, leaving the caller free to answer 413. Pairs are
+// left as they arrived, call [httpraw.Form.Decode] to decode them in place.
+//
+// Unlike http.Request.ParseForm the query string is not folded in, reach it with
+// [Exchange.RequestQuery] or [Exchange.AppendQuery]. The body is consumed, so
+// call this before [Exchange.ReadBody].
+//
+// A request with no Content-Length has no body, RFC 9112 6.3, and yields an
+// empty form. Use [Exchange.RequestContentLength] to tell that apart from a body
+// that arrived empty. backoff paces reads that return no data, as in [Handle].
+func (exch *Exchange) RequestParseForm(dst *httpraw.Form, buf []byte, backoff lneto.BackoffStrategy) error {
+	if !httpraw.MediaTypeIs(exch.RequestContentType(), "application/x-www-form-urlencoded") {
+		return errNotFormEncoded
+	} else if exch.RequestHeader("Transfer-Encoding") != nil {
+		// Chunked bodies are framed, so reading Content-Length bytes off the
+		// wire would parse chunk sizes as form data. httpraw does not decode them.
+		return errUnsupportedTransferCoding
+	}
+	length, err := exch.RequestContentLength()
+	if err != nil {
+		dst.Reset(buf[:0])
+		return dst.Parse() // No length is no body, RFC 9112 6.3.
+	} else if length > int64(len(buf)) {
+		return lneto.ErrBufferFull // Refuse before reading, caller may answer 413.
+	}
+	buf = buf[:length]
+	var consecutiveBackoffs uint
+	for read := 0; read < len(buf); {
+		n, err := exch.ReadBody(buf[read:])
+		if err != nil {
+			return err
+		} else if n == 0 {
+			backoff.Do(consecutiveBackoffs)
+			consecutiveBackoffs++
+			continue
+		}
+		consecutiveBackoffs = 0
+		read += n
+	}
+	dst.Reset(buf)
+	return dst.Parse()
+}
+
+// RequestParseMultipart prepares dst from the boundary parameter of the
+// request's Content-Type field. It reads no body: multipart parts declare no
+// length, so the caller drives the loop with a buffer it owns and decides per
+// part what to keep and when a part has grown too large.
+//
+// A part header and the bytes held back by [httpraw.Multipart.NextBody] both ask
+// to be completed the same way: compact what is left to the front of the buffer
+// and read more in behind it. A buffer that fills without completing either is
+// the caller's cue that the part is too large to go on with.
+//
+//	// refill compacts rest to the front of buf and reads more of the body in.
+//	refill := func(rest []byte) ([]byte, error) {
+//		n := copy(buf, rest)
+//		if n == len(buf) {
+//			return nil, lneto.ErrBufferFull
+//		}
+//		nr, err := exch.ReadBody(buf[n:])
+//		return buf[:n+nr], err
+//	}
+//
+//	err := exch.RequestParseMultipart(&mp)
+//	rest := buf[:0]
+//	for {
+//		next, err := mp.NextHeader(&hdr, rest)
+//		if err == io.EOF {
+//			break // Closing delimiter, body done.
+//		} else if err == httpraw.ErrNeedMoreData {
+//			rest, err = refill(rest)
+//			// ...handle err, then:
+//			continue
+//		} else if err != nil {
+//			return err
+//		}
+//		rest = next
+//		for {
+//			body, next, done := mp.NextBody(rest)
+//			// Consume body for hdr.Name, hdr.Filename.
+//			rest = next
+//			if done {
+//				break
+//			}
+//			rest, err = refill(rest)
+//			if err != nil {
+//				return err
+//			}
+//		}
+//	}
+func (exch *Exchange) RequestMultipart() (mp httpraw.Multipart, err error) {
+	contentType := exch.RequestContentType()
+	if !httpraw.MediaTypeIs(contentType, "multipart/form-data") {
+		return mp, errNotMultipart
+	}
+	return mp, mp.SetContentType(contentType)
+}
+
 // RequestHeader returns the value of the first request header field matching
 // key, or nil if absent. Key matching is case sensitive.
 func (exch *Exchange) RequestHeader(key string) []byte {

http/httphi/exchange_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"io"
+	"strconv"
 	"strings"
 
 	"testing"
@@ -611,3 +612,249 @@ func TestExchangeAppendQueryReusesBuffer(t *testing.T) {
 		t.Errorf("AppendQuery allocated %v times into a buffer with capacity, want 0", allocs)
 	}
 }
+
+// formString renders a form as "key=value" pairs joined by '|', a pair with no
+// value shown as the bare key.
+func formString(f *httpraw.Form) string {
+	var sb strings.Builder
+	for i := 0; i < f.Len(); i++ {
+		if i > 0 {
+			sb.WriteByte('|')
+		}
+		key, value := f.Pair(i)
+		sb.Write(key)
+		if value != nil {
+			sb.WriteByte('=')
+			sb.Write(value)
+		}
+	}
+	return sb.String()
+}
+
+const formType = "Content-Type: application/x-www-form-urlencoded\r\n"
+
+func TestExchangeRequestParseForm(t *testing.T) {
+	for _, test := range []struct {
+		name    string
+		request string
+		bufSize int // Defaults to 64.
+		want    string
+		wantErr error
+	}{
+		{
+			name:    "pairs",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "Content-Length: 11\r\n\r\na=1&b=2&c=3",
+			want:    "a=1|b=2|c=3",
+		}, {
+			// A flag and an empty value stay distinguishable, unlike http.FormValue.
+			name:    "flag and empty",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "Content-Length: 4\r\n\r\na&b=",
+			want:    "a|b=",
+		}, {
+			name:    "left encoded",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "Content-Length: 7\r\n\r\nn=a%20b",
+			want:    "n=a%20b",
+		}, {
+			name:    "media type parameters",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\nContent-Type: application/x-www-form-urlencoded; charset=utf-8\r\nContent-Length: 3\r\n\r\na=1",
+			want:    "a=1",
+		}, {
+			// Only the body is parsed: the query string is not folded in.
+			name:    "query not folded",
+			request: "POST /f?q=go HTTP/1.1\r\nHost: h\r\n" + formType + "Content-Length: 3\r\n\r\na=1",
+			want:    "a=1",
+		}, {
+			// No Content-Length means no body at all, RFC 9112 6.3.
+			name:    "no content length",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "\r\n",
+			want:    "",
+		}, {
+			name:    "wrong media type",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\nContent-Type: text/plain\r\nContent-Length: 3\r\n\r\na=1",
+			wantErr: errNotFormEncoded,
+		}, {
+			name:    "no media type",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\nContent-Length: 3\r\n\r\na=1",
+			wantErr: errNotFormEncoded,
+		}, {
+			name:    "chunked",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "Transfer-Encoding: chunked\r\n\r\n3\r\na=1\r\n0\r\n\r\n",
+			wantErr: errUnsupportedTransferCoding,
+		}, {
+			name:    "body larger than buffer",
+			request: "POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "Content-Length: 11\r\n\r\na=1&b=2&c=3",
+			bufSize: 4,
+			wantErr: lneto.ErrBufferFull,
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			bufSize := test.bufSize
+			if bufSize == 0 {
+				bufSize = 64
+			}
+			var form httpraw.Form
+			var gotErr error
+			var sm MuxSlice
+			sm.Reset(1)
+			sm.Handle("/f", func(exch *Exchange) {
+				gotErr = exch.RequestParseForm(&form, make([]byte, bufSize), nopBackoff)
+			})
+			serve(t, test.request, &sm)
+			if gotErr != test.wantErr {
+				t.Fatalf("want error %v, got %v", test.wantErr, gotErr)
+			}
+			if got := formString(&form); test.wantErr == nil && got != test.want {
+				t.Errorf("want %q, got %q", test.want, got)
+			}
+		})
+	}
+}
+
+// A body arriving after the header, in its own segment, must still be parsed whole.
+func TestExchangeRequestParseFormSplit(t *testing.T) {
+	conn := newConn("POST /f HTTP/1.1\r\nHost: h\r\n" + formType + "Content-Length: 11\r\n\r\na=1&")
+	conn.AddSegment("b=2&c=3")
+	conn.Hangup()
+	var form httpraw.Form
+	var gotErr error
+	var sm MuxSlice
+	sm.Reset(1)
+	sm.Handle("/f", func(exch *Exchange) {
+		gotErr = exch.RequestParseForm(&form, make([]byte, 64), nopBackoff)
+	})
+	exch := newExchange(t, conn, 1024, false)
+	if err := Handle(exch, &sm, nopBackoff); err != nil {
+		t.Fatal(err)
+	}
+	if gotErr != nil {
+		t.Fatal(gotErr)
+	}
+	if got := formString(&form); got != "a=1|b=2|c=3" {
+		t.Errorf("want %q, got %q", "a=1|b=2|c=3", got)
+	}
+}
+
+// Decode is the caller's call, and it must reach both keys and values.
+func TestExchangeRequestParseFormDecode(t *testing.T) {
+	var form httpraw.Form
+	var sm MuxSlice
+	sm.Reset(1)
+	sm.Handle("/f", func(exch *Exchange) {
+		if err := exch.RequestParseForm(&form, make([]byte, 64), nopBackoff); err != nil {
+			t.Error(err)
+		} else if err = form.Decode(); err != nil {
+			t.Error(err)
+		}
+	})
+	serve(t, "POST /f HTTP/1.1\r\nHost: h\r\n"+formType+"Content-Length: 16\r\n\r\na+b=c%20d&e=f%2B", &sm)
+	if got := formString(&form); got != "a b=c d|e=f+" {
+		t.Errorf("want %q, got %q", "a b=c d|e=f+", got)
+	}
+}
+
+// refill compacts the bytes the multipart parser held back to the front of buf
+// and reads more of the body in behind them.
+func refill(exch *Exchange, buf, rest []byte) ([]byte, error) {
+	n := copy(buf, rest)
+	if n == len(buf) {
+		return nil, lneto.ErrBufferFull // A delimiter or part header longer than buf.
+	}
+	nr, err := exch.ReadBody(buf[n:])
+	return buf[:n+nr], err
+}
+
+// The whole multipart loop as a handler writes it, over a body split so that a
+// part straddles two reads and the caller must compact and refill.
+func TestExchangeRequestParseMultipart(t *testing.T) {
+	const (
+		boundary = "--xyz"
+		head     = "POST /f HTTP/1.1\r\nHost: h\r\nContent-Type: multipart/form-data; boundary=" + boundary + "\r\n\r\n"
+		part1    = "----xyz\r\nContent-Disposition: form-data; name=\"caption\"\r\n\r\nhi there\r\n"
+		part2    = "----xyz\r\nContent-Disposition: form-data; name=\"photo\"; filename=\"beach.png\"\r\n\r\n\x89PNG\r\n\x00\r\n"
+		tail     = "----xyz--\r\n"
+	)
+	conn := newConn(head + part1 + part2[:20])
+	conn.AddSegment(part2[20:] + tail)
+	conn.Hangup()
+
+	var got []string
+	var gotErr error
+	var sm MuxSlice
+	sm.Reset(1)
+	sm.Handle("/f", func(exch *Exchange) {
+		var mp httpraw.Multipart
+		if mp, gotErr = exch.RequestMultipart(); gotErr != nil {
+			return
+		}
+		var hdr httpraw.MultipartHeader
+		buf := make([]byte, 128)
+		rest := buf[:0]
+		for {
+			next, err := mp.NextHeader(&hdr, rest)
+			if err == io.EOF {
+				return // Closing delimiter, body done.
+			} else if err == httpraw.ErrNeedMoreData {
+				if rest, gotErr = refill(exch, buf, rest); gotErr != nil {
+					return
+				}
+				continue
+			} else if err != nil {
+				gotErr = err
+				return
+			}
+			name, total := string(hdr.Name), 0
+			rest = next
+			for {
+				body, next, done := mp.NextBody(rest)
+				total += len(body)
+				rest = next
+				if done {
+					break
+				}
+				if rest, gotErr = refill(exch, buf, rest); gotErr != nil {
+					return
+				}
+			}
+			got = append(got, name+":"+strconv.Itoa(total))
+		}
+	})
+	exch := newExchange(t, conn, 1024, false)
+	if err := Handle(exch, &sm, nopBackoff); err != nil {
+		t.Fatal(err)
+	}
+	if gotErr != nil {
+		t.Fatal(gotErr)
+	}
+	const want = "caption:8|photo:7"
+	if strings.Join(got, "|") != want {
+		t.Errorf("want %q, got %q", want, strings.Join(got, "|"))
+	}
+}
+
+// A request that is not multipart, or whose boundary is missing, must be refused.
+func TestExchangeRequestParseMultipartRejects(t *testing.T) {
+	for _, test := range []struct {
+		contentType string
+		wantErr     bool
+	}{
+		{contentType: "multipart/form-data; boundary=xyz"},
+		{contentType: "application/x-www-form-urlencoded", wantErr: true},
+		{contentType: "multipart/form-data", wantErr: true}, // Boundary is required.
+		{contentType: "", wantErr: true},
+	} {
+		var gotErr error
+		var sm MuxSlice
+		sm.Reset(1)
+		sm.Handle("/f", func(exch *Exchange) {
+			_, gotErr = exch.RequestMultipart()
+		})
+		request := "POST /f HTTP/1.1\r\nHost: h\r\n"
+		if test.contentType != "" {
+			request += "Content-Type: " + test.contentType + "\r\n"
+		}
+		serve(t, request+"\r\n", &sm)
+		if (gotErr != nil) != test.wantErr {
+			t.Errorf("%q: want error %v, got %v", test.contentType, test.wantErr, gotErr)
+		}
+	}
+}

http/httphi/router.go

@@ -22,6 +22,10 @@ var (
 	errNoRequestProto = errors.New("httphi: request line with no HTTP version")
 	errBusyExchanges  = errors.New("httphi: exchanges still serving, cannot reuse their buffers")
 	errRouterTornDown = errors.New("httphi: router torn down, configure it before serving")
+
+	errNotFormEncoded            = errors.New("httphi: request body is not application/x-www-form-urlencoded")
+	errNotMultipart              = errors.New("httphi: request body is not multipart/form-data")
+	errUnsupportedTransferCoding = errors.New("httphi: transfer coding not decoded, read the body directly")
 )
 
 type conn = io.ReadWriteCloser

http/httpraw/header.go

@@ -4,15 +4,17 @@ import (
 	"bytes"
 	"io"
 	"slices"
+	"strconv"
 )
 
 const (
-	methodGet        = "GET"
-	strHTTP11        = "HTTP/1.1"
-	strCRLF          = "\r\n"
-	headerCookie     = "Cookie"
-	headerConnection = "Connection"
-	strClose         = "close"
+	methodGet           = "GET"
+	strHTTP11           = "HTTP/1.1"
+	strCRLF             = "\r\n"
+	headerCookie        = "Cookie"
+	headerConnection    = "Connection"
+	headerContentLength = "Content-Length"
+	strClose            = "close"
 )
 
 // Flags is a bitset of signals gathered while parsing or building a header,
@@ -343,6 +345,28 @@ func (h *Header) Get(key string) []byte {
 	return nil
 }
 
+// ContentLength returns the body length declared by the Content-Length field.
+// Fails with an error if the field is absent, which for a request means the
+// message has no body at all unless a transfer coding applies, RFC 9112 6.3.
+// The value must be digits only, so a negative or list-valued field is rejected
+// rather than guessed at.
+func (h *Header) ContentLength() (int64, error) {
+	kv := h.peekHeader(headerContentLength)
+	if !kv.isValid() {
+		return 0, errNoContentLength
+	}
+	value := trimOWS(h.hbuf.musttoken(kv.value))
+	if len(value) == 0 {
+		return 0, errBadContentLength
+	}
+	// Unsigned parse of 63 bits rejects a sign and anything past int64's range.
+	n, err := strconv.ParseUint(b2s(value), 10, 63)
+	if err != nil {
+		return 0, errBadContentLength // strconv's error allocates and is not comparable.
+	}
+	return int64(n), nil
+}
+
 // Add adds a new key-value pair to the HTTP header. Calling Add mangles the buffer.
 func (h *Header) Add(key, value string) {
 	h.appendHeader(key, value)

http/httpraw/header_test.go

@@ -173,6 +173,39 @@ func TestHeaderRequestPath(t *testing.T) {
 	}
 }
 
+func TestHeaderContentLength(t *testing.T) {
+	for _, test := range []struct {
+		field   string // Extra header lines, empty for an absent field.
+		want    int64
+		wantErr error
+	}{
+		{field: "Content-Length: 0", want: 0},
+		{field: "Content-Length: 12", want: 12},
+		{field: "Content-Length:  12 ", want: 12}, // OWS around the value, RFC 9110 5.6.3.
+		{field: "Content-Length: 9223372036854775807", want: 9223372036854775807},
+		{field: "", wantErr: errNoContentLength},                     // No body, RFC 9112 6.3.
+		{field: "Content-Length:", wantErr: errBadContentLength},     // Present but empty.
+		{field: "Content-Length: -1", wantErr: errBadContentLength},  // Digits only, RFC 9112 6.2.
+		{field: "Content-Length: 1 2", wantErr: errBadContentLength}, // Not a list.
+		{field: "Content-Length: 9223372036854775808", wantErr: errBadContentLength},
+	} {
+		var h Header
+		raw := "POST / HTTP/1.1\r\nHost: h\r\n"
+		if test.field != "" {
+			raw += test.field + "\r\n"
+		}
+		if err := h.ParseBytes(false, []byte(raw+"\r\n")); err != nil {
+			t.Fatal(err)
+		}
+		got, err := h.ContentLength()
+		if err != test.wantErr {
+			t.Errorf("%q: want error %v, got %v", test.field, test.wantErr, err)
+		} else if err == nil && got != test.want {
+			t.Errorf("%q: want %d, got %d", test.field, test.want, got)
+		}
+	}
+}
+
 func TestNextQueryPair(t *testing.T) {
 	for _, test := range []struct {
 		uri  string

http/httpraw/multipart.go

@@ -49,9 +49,12 @@ type MultipartHeader struct {
 	Filename []byte
 }
 
-// SetContentType sets the boundary parameter of a Content-Type field value,
-// i.e: "abc123" for "multipart/form-data; boundary=abc123". The leading "--" of
-// the wire delimiter is not included. Returns nil if there is no such parameter.
+// SetContentType sets [Multipart.Boundary] from the boundary parameter of a
+// Content-Type field value, i.e: "abc123" for
+// "multipart/form-data; boundary=abc123". The leading "--" the delimiter carries
+// on the wire is not included. Fails when the parameter is absent or is not
+// 1 to 70 characters long, RFC 2046 5.1.1; a zero length boundary would match
+// every "--" in the body.
 func (m *Multipart) SetContentType(contentType []byte) error {
 	m.Boundary = ContentParam(contentType, "boundary")
 	if len(m.Boundary) == 0 || len(m.Boundary) > 70 {
@@ -86,7 +89,7 @@ func (m *Multipart) NextHeader(dst *MultipartHeader, data []byte) (rest []byte,
 	if after >= len(data) {
 		return nil, ErrNeedMoreData
 	} else if data[after] != '\n' {
-		return nil, errInvalidName // Junk between delimiter and part.
+		return nil, errBadDelimiter
 	}
 	after++
 	end := bytes.Index(data[after:], []byte("\r\n\r\n"))
@@ -155,6 +158,17 @@ func (m *Multipart) indexPartEnd(data []byte) int {
 	return -1
 }
 
+// MediaTypeIs reports whether a Content-Type field value carries the given
+// media type, ignoring case and any parameters that follow it, i.e: true for
+// "text/plain; charset=utf-8" and media type "text/plain". mediaType must be
+// ASCII lowercase. RFC 9110 8.3.1.
+func MediaTypeIs(value []byte, mediaType string) bool {
+	if semi := bytes.IndexByte(value, ';'); semi >= 0 {
+		value = value[:semi]
+	}
+	return equalFold(trimOWS(value), mediaType)
+}
+
 // ContentParam returns the value of a parameter of a header field value, i.e:
 // "utf-8" for key "charset" of "text/plain; charset=utf-8". Quoted values are
 // returned without their quotes and with escapes left as they appear on the

http/httpraw/multipart_test.go

@@ -28,17 +28,25 @@ func TestMultipartBoundary(t *testing.T) {
 	for _, test := range []struct {
 		contentType string
 		want        string
+		wantErr     bool
 	}{
 		{contentType: "multipart/form-data; boundary=abc123", want: "abc123"},
 		{contentType: "multipart/form-data; boundary=\"a b\"", want: "a b"},
 		{contentType: "multipart/form-data; charset=utf-8; boundary=xyz", want: "xyz"},
-		{contentType: "multipart/form-data; BOUNDARY=xyz", want: "xyz"}, // Keys are case insensitive.
-		{contentType: "multipart/form-data", want: ""},                  // Absent.
-		{contentType: "application/x-www-form-urlencoded", want: ""},
+		{contentType: "multipart/form-data; BOUNDARY=xyz", want: "xyz"},   // Keys are case insensitive.
+		{contentType: "multipart/form-data", wantErr: true},               // Absent, RFC 2046 5.1.1 requires it.
+		{contentType: "application/x-www-form-urlencoded", wantErr: true}, // Not multipart at all.
+		{contentType: "multipart/form-data; boundary=", wantErr: true},    // Empty matches every "--".
 	} {
 		err := mp.SetContentType([]byte(test.contentType))
-		if err != nil {
-			t.Skip("asdasd")
+		if test.wantErr {
+			if err == nil {
+				t.Errorf("%q: want error, got boundary %q", test.contentType, mp.Boundary)
+			}
+			continue
+		} else if err != nil {
+			t.Errorf("%q: %s", test.contentType, err)
+			continue
 		}
 		got := string(mp.Boundary)
 		if got != test.want {
@@ -47,6 +55,28 @@ func TestMultipartBoundary(t *testing.T) {
 	}
 }
 
+func TestMediaTypeIs(t *testing.T) {
+	for _, test := range []struct {
+		value string
+		media string
+		want  bool
+	}{
+		{value: "text/plain", media: "text/plain", want: true},
+		{value: "text/plain; charset=utf-8", media: "text/plain", want: true},
+		{value: "text/plain;charset=utf-8", media: "text/plain", want: true},
+		{value: "Text/Plain", media: "text/plain", want: true}, // Case insensitive, RFC 9110 8.3.1.
+		{value: " text/plain ; x=1", media: "text/plain", want: true},
+		{value: "text/plain", media: "text/html"},
+		{value: "text/plainish", media: "text/plain"}, // Prefix must not match.
+		{value: "", media: "text/plain"},
+		{value: "multipart/form-data; boundary=abc", media: "multipart/form-data", want: true},
+	} {
+		if got := MediaTypeIs([]byte(test.value), test.media); got != test.want {
+			t.Errorf("%q is %q: want %v, got %v", test.value, test.media, test.want, got)
+		}
+	}
+}
+
 func TestContentParam(t *testing.T) {
 	for _, test := range []struct {
 		value string
@@ -106,6 +136,16 @@ func TestNextPartHeaderNeedMore(t *testing.T) {
 	}
 }
 
+// Junk between the delimiter and the part header is a multipart framing error,
+// not a header field name error.
+func TestNextPartHeaderJunk(t *testing.T) {
+	m := Multipart{Boundary: []byte("abc")}
+	var hdr MultipartHeader
+	if _, err := m.NextHeader(&hdr, []byte("--abcX\r\nA: b\r\n\r\n")); err != errBadDelimiter {
+		t.Errorf("want errBadDelimiter, got %v", err)
+	}
+}
+
 // The closing delimiter ends iteration.
 func TestNextPartHeaderEnd(t *testing.T) {
 	m := Multipart{Boundary: []byte(multiBoundary)}

http/httpraw/parse.go

@@ -33,6 +33,9 @@ var (
 	errCookiesParsed    = errors.New("cookies already parsed, reset before parsing again")
 	errBufferTooLarge   = errors.New("httpraw: buffer exceeds max size (offsets are uint16)")
 	errBadPercentEncode = errors.New("httpraw: invalid percent-encoding in URL")
+	errBadDelimiter     = errors.New("httpraw: junk between multipart delimiter and part")
+	errNoContentLength  = errors.New("httpraw: no Content-Length field")
+	errBadContentLength = errors.New("httpraw: invalid Content-Length value")
 )
 
 // maxBufLen bounds the header buffer. Offsets/lengths are stored as uint16