Merge pull request #5 from marten-seemann/decode-full

implement DecodeFull for the decoder

Author: marten-seemann

decoder.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"sync"
 
 	"golang.org/x/net/http2/hpack"
 )
@@ -35,6 +36,8 @@ var errNeedMore = errors.New("need more data")
 // A Decoder is the decoding context for incremental processing of
 // header blocks.
 type Decoder struct {
+	mutex sync.Mutex
+
 	emitFunc func(f HeaderField)
 
 	readRequiredInsertCount bool
@@ -63,6 +66,13 @@ func (d *Decoder) Write(p []byte) (int, error) {
 		return 0, nil
 	}
 
+	d.mutex.Lock()
+	n, err := d.writeLocked(p)
+	d.mutex.Unlock()
+	return n, err
+}
+
+func (d *Decoder) writeLocked(p []byte) (int, error) {
 	// Only copy the data if we have to. Optimistically assume
 	// that p will contain a complete header block.
 	if d.saveBuf.Len() == 0 {
@@ -83,6 +93,29 @@ func (d *Decoder) Write(p []byte) (int, error) {
 	return len(p), nil
 }
 
+// DecodeFull decodes an entire block.
+func (d *Decoder) DecodeFull(p []byte) ([]HeaderField, error) {
+	if len(p) == 0 {
+		return []HeaderField{}, nil
+	}
+
+	d.mutex.Lock()
+	defer d.mutex.Unlock()
+
+	saveFunc := d.emitFunc
+	defer func() { d.emitFunc = saveFunc }()
+
+	var hf []HeaderField
+	d.emitFunc = func(f HeaderField) { hf = append(hf, f) }
+	if _, err := d.writeLocked(p); err != nil {
+		return nil, err
+	}
+	if err := d.Close(); err != nil {
+		return nil, err
+	}
+	return hf, nil
+}
+
 // Close declares that the decoding is complete and resets the Decoder
 // to be reused again for a new header block. If there is any remaining
 // data in the decoder's buffer, Close returns an error.

decoder_test.go

@@ -1,6 +1,8 @@
 package qpack
 
 import (
+	"bytes"
+
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 	"golang.org/x/net/http2/hpack"
@@ -175,4 +177,50 @@ var _ = Describe("Decoder", func() {
 			doPartialWrites(data)
 		})
 	})
+
+	Context("using DecodeFull", func() {
+		It("decodes nothing", func() {
+			data, err := NewDecoder(nil).DecodeFull([]byte{})
+			Expect(err).ToNot(HaveOccurred())
+			Expect(data).To(BeEmpty())
+		})
+
+		It("decodes multiple entries", func() {
+			buf := &bytes.Buffer{}
+			enc := NewEncoder(buf)
+			Expect(enc.WriteField(HeaderField{Name: "foo", Value: "bar"})).To(Succeed())
+			Expect(enc.WriteField(HeaderField{Name: "lorem", Value: "ipsum"})).To(Succeed())
+			data, err := NewDecoder(nil).DecodeFull(buf.Bytes())
+			Expect(err).ToNot(HaveOccurred())
+			Expect(data).To(Equal([]HeaderField{
+				{Name: "foo", Value: "bar"},
+				{Name: "lorem", Value: "ipsum"},
+			}))
+		})
+
+		It("returns an error if the data is incomplete", func() {
+			buf := &bytes.Buffer{}
+			enc := NewEncoder(buf)
+			Expect(enc.WriteField(HeaderField{Name: "foo", Value: "bar"})).To(Succeed())
+			_, err := NewDecoder(nil).DecodeFull(buf.Bytes()[:buf.Len()-2])
+			Expect(err).To(MatchError("decoding error: truncated headers"))
+		})
+
+		It("restores the emitFunc afterwards", func() {
+			var emitFuncCalled bool
+			emitFunc := func(HeaderField) {
+				emitFuncCalled = true
+			}
+			decoder := NewDecoder(emitFunc)
+			buf := &bytes.Buffer{}
+			enc := NewEncoder(buf)
+			Expect(enc.WriteField(HeaderField{Name: "foo", Value: "bar"})).To(Succeed())
+			_, err := decoder.DecodeFull(buf.Bytes())
+			Expect(err).ToNot(HaveOccurred())
+			Expect(emitFuncCalled).To(BeFalse())
+			_, err = decoder.Write(buf.Bytes())
+			Expect(err).ToNot(HaveOccurred())
+			Expect(emitFuncCalled).To(BeTrue())
+		})
+	})
 })