Support headers

Signed-off-by: Maksym Pavlenko <makpav@amazon.com>

client.go

@@ -99,6 +99,10 @@ func (c *Client) Call(ctx context.Context, service, method string, req, resp int
 		cresp = &Response{}
 	)
 
+	if headers, ok := GetHeaders(ctx); ok {
+		creq.Headers = headers
+	}
+
 	if dl, ok := ctx.Deadline(); ok {
 		creq.TimeoutNano = dl.Sub(time.Now()).Nanoseconds()
 	}

header.go

@@ -0,0 +1,86 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package ttrpc
+
+import "context"
+
+// Headers represents the key-value pairs (similar to http.Header) to be passed to ttrpc server from a client.
+type Headers map[string]StringList
+
+// Get returns the headers for a given key when they exist.
+// If there are no headers, a nil slice and false are returned.
+func (h Headers) Get(key string) ([]string, bool) {
+	list, ok := h[key]
+	if !ok || len(list.List) == 0 {
+		return nil, false
+	}
+
+	return list.List, true
+}
+
+// Set sets the provided values for a given key.
+// The values will overwrite any existing values.
+// If no values provided, a key will be deleted.
+func (h Headers) Set(key string, values ...string) {
+	if len(values) == 0 {
+		delete(h, key)
+		return
+	}
+
+	h[key] = StringList{List: values}
+}
+
+// Append appends additional values to the given key.
+func (h Headers) Append(key string, values ...string) {
+	if len(values) == 0 {
+		return
+	}
+
+	list, ok := h[key]
+	if ok {
+		h.Set(key, append(list.List, values...)...)
+	} else {
+		h.Set(key, values...)
+	}
+}
+
+type headerKey struct{}
+
+// GetHeaders retrieves headers from context.Context (previously attached with WithHeaders)
+func GetHeaders(ctx context.Context) (Headers, bool) {
+	headers, ok := ctx.Value(headerKey{}).(Headers)
+	return headers, ok
+}
+
+// GetHeader gets a specific header value by name from context.Context
+func GetHeader(ctx context.Context, name string) (string, bool) {
+	headers, ok := GetHeaders(ctx)
+	if !ok {
+		return "", false
+	}
+
+	if list, ok := headers.Get(name); ok {
+		return list[0], true
+	}
+
+	return "", false
+}
+
+// WithHeaders attaches headers map to a context.Context
+func WithHeaders(ctx context.Context, headers Headers) context.Context {
+	return context.WithValue(ctx, headerKey{}, headers)
+}

header_test.go

@@ -0,0 +1,108 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package ttrpc
+
+import (
+	"context"
+	"testing"
+)
+
+func TestHeaders_Get(t *testing.T) {
+	hdr := make(Headers)
+	hdr.Set("foo", "1", "2")
+
+	if list, ok := hdr.Get("foo"); !ok {
+		t.Error("key not found")
+	} else if len(list) != 2 {
+		t.Errorf("unexpected number of values: %d", len(list))
+	} else if list[0] != "1" {
+		t.Errorf("invalid header value at 0: %s", list[0])
+	} else if list[1] != "2" {
+		t.Errorf("invalid header value at 1: %s", list[1])
+	}
+}
+
+func TestHeaders_GetInvalidKey(t *testing.T) {
+	hdr := make(Headers)
+	hdr.Set("foo", "1", "2")
+
+	if _, ok := hdr.Get("invalid"); ok {
+		t.Error("found invalid key")
+	}
+}
+
+func TestHeaders_Unset(t *testing.T) {
+	hdr := make(Headers)
+	hdr.Set("foo", "1", "2")
+	hdr.Set("foo")
+
+	if _, ok := hdr.Get("foo"); ok {
+		t.Error("key not deleted")
+	}
+}
+
+func TestHeader_Replace(t *testing.T) {
+	hdr := make(Headers)
+	hdr.Set("foo", "1", "2")
+	hdr.Set("foo", "3", "4")
+
+	if list, ok := hdr.Get("foo"); !ok {
+		t.Error("key not found")
+	} else if len(list) != 2 {
+		t.Errorf("unexpected number of values: %d", len(list))
+	} else if list[0] != "3" {
+		t.Errorf("invalid header value at 0: %s", list[0])
+	} else if list[1] != "4" {
+		t.Errorf("invalid header value at 1: %s", list[1])
+	}
+}
+
+func TestHeaders_Append(t *testing.T) {
+	hdr := make(Headers)
+	hdr.Set("foo", "1")
+	hdr.Append("foo", "2")
+	hdr.Append("bar", "3")
+
+	if list, ok := hdr.Get("foo"); !ok {
+		t.Error("key not found")
+	} else if len(list) != 2 {
+		t.Errorf("unexpected number of values: %d", len(list))
+	} else if list[0] != "1" {
+		t.Errorf("invalid header value at 0: %s", list[0])
+	} else if list[1] != "2" {
+		t.Errorf("invalid header value at 1: %s", list[1])
+	}
+
+	if list, ok := hdr.Get("bar"); !ok {
+		t.Error("key not found")
+	} else if list[0] != "3" {
+		t.Errorf("invalid value: %s", list[0])
+	}
+}
+
+func TestHeaders_Context(t *testing.T) {
+	hdr := make(Headers)
+	hdr.Set("foo", "bar")
+
+	ctx := WithHeaders(context.Background(), hdr)
+
+	if bar, ok := GetHeader(ctx, "foo"); !ok {
+		t.Error("header not found")
+	} else if bar != "bar" {
+		t.Errorf("invalid header value: %q", bar)
+	}
+}

server.go

@@ -466,6 +466,10 @@ func (c *serverConn) run(sctx context.Context) {
 var noopFunc = func() {}
 
 func getRequestContext(ctx context.Context, req *Request) (retCtx context.Context, cancel func()) {
+	if req.Headers != nil {
+		ctx = WithHeaders(ctx, req.Headers)
+	}
+
 	cancel = noopFunc
 	if req.TimeoutNano == 0 {
 		return ctx, cancel

server_test.go

@@ -61,6 +61,7 @@ func (tc *testingClient) Test(ctx context.Context, req *testPayload) (*testPaylo
 type testPayload struct {
 	Foo      string `protobuf:"bytes,1,opt,name=foo,proto3"`
 	Deadline int64  `protobuf:"varint,2,opt,name=deadline,proto3"`
+	Hdr      string `protobuf:"bytes,3,opt,name=hdr,proto3"`
 }
 
 func (r *testPayload) Reset()         { *r = testPayload{} }
@@ -75,6 +76,11 @@ func (s *testingServer) Test(ctx context.Context, req *testPayload) (*testPayloa
 	if dl, ok := ctx.Deadline(); ok {
 		tp.Deadline = dl.UnixNano()
 	}
+
+	if v, ok := GetHeader(ctx, "foo"); ok {
+		tp.Hdr = v
+	}
+
 	return tp, nil
 }
 
@@ -540,6 +546,8 @@ func roundTrip(ctx context.Context, t *testing.T, client *testingClient, value s
 		}
 	)
 
+	ctx = WithHeaders(ctx, Headers{"foo": makeStringList("bar")})
+
 	resp, err := client.Test(ctx, tp)
 	if err != nil {
 		t.Fatal(err)
@@ -547,7 +555,7 @@ func roundTrip(ctx context.Context, t *testing.T, client *testingClient, value s
 
 	results <- callResult{
 		input:    tp,
-		expected: &testPayload{Foo: strings.Repeat(tp.Foo, 2)},
+		expected: &testPayload{Foo: strings.Repeat(tp.Foo, 2), Hdr: "bar"},
 		received: resp,
 	}
 }

types.go

@@ -23,10 +23,11 @@ import (
 )
 
 type Request struct {
-	Service     string `protobuf:"bytes,1,opt,name=service,proto3"`
-	Method      string `protobuf:"bytes,2,opt,name=method,proto3"`
-	Payload     []byte `protobuf:"bytes,3,opt,name=payload,proto3"`
-	TimeoutNano int64  `protobuf:"varint,4,opt,name=timeout_nano,proto3"`
+	Service     string  `protobuf:"bytes,1,opt,name=service,proto3"`
+	Method      string  `protobuf:"bytes,2,opt,name=method,proto3"`
+	Payload     []byte  `protobuf:"bytes,3,opt,name=payload,proto3"`
+	TimeoutNano int64   `protobuf:"varint,4,opt,name=timeout_nano,proto3"`
+	Headers     Headers `protobuf:"bytes,5,opt,name=headers,proto3" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
 }
 
 func (r *Request) Reset()         { *r = Request{} }
@@ -41,3 +42,13 @@ type Response struct {
 func (r *Response) Reset()         { *r = Response{} }
 func (r *Response) String() string { return fmt.Sprintf("%+#v", r) }
 func (r *Response) ProtoMessage()  {}
+
+type StringList struct {
+	List []string `protobuf:"bytes,1,rep,name=list,proto3"`
+}
+
+func (r *StringList) Reset()         { *r = StringList{} }
+func (r *StringList) String() string { return fmt.Sprintf("%+#v", r) }
+func (r *StringList) ProtoMessage()  {}
+
+func makeStringList(item ...string) StringList { return StringList{List: item} }