2 files changed, 124 insertions, 0 deletions
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index e92ec0c24..cdcfb8321 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -471,6 +471,14 @@ type Stack struct {
 	// randomGenerator is an injectable pseudo random generator that can be
 	// used when a random number is required.
 	randomGenerator *mathrand.Rand
+
+	// sendBufferSize holds the min/default/max send buffer sizes for
+	// endpoints other than TCP.
+	sendBufferSize SendBufferSizeOption
+
+	// receiveBufferSize holds the min/default/max receive buffer sizes for
+	// endpoints other than TCP.
+	receiveBufferSize ReceiveBufferSizeOption
 }
 
 // UniqueID is an abstract generator of unique identifiers.
@@ -683,6 +691,16 @@ func New(opts Options) *Stack {
 		tempIIDSeed:          opts.TempIIDSeed,
 		forwarder:            newForwardQueue(),
 		randomGenerator:      mathrand.New(randSrc),
+		sendBufferSize: SendBufferSizeOption{
+			Min:     MinBufferSize,
+			Default: DefaultBufferSize,
+			Max:     DefaultMaxBufferSize,
+		},
+		receiveBufferSize: ReceiveBufferSizeOption{
+			Min:     MinBufferSize,
+			Default: DefaultBufferSize,
+			Max:     DefaultMaxBufferSize,
+		},
 	}
 
 	// Add specified network protocols.
diff --git a/pkg/tcpip/stack/stack_options.go b/pkg/tcpip/stack/stack_options.go
new file mode 100644
index 000000000..0b093e6c5
--- /dev/null
+++ b/pkg/tcpip/stack/stack_options.go
@@ -0,0 +1,106 @@
+// Copyright 2020 The gVisor 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 stack
+
+import "gvisor.dev/gvisor/pkg/tcpip"
+
+const (
+	// MinBufferSize is the smallest size of a receive or send buffer.
+	MinBufferSize = 4 << 10 // 4 KiB
+
+	// DefaultBufferSize is the default size of the send/recv buffer for a
+	// transport endpoint.
+	DefaultBufferSize = 212 << 10 // 212 KiB
+
+	// DefaultMaxBufferSize is the default maximum permitted size of a
+	// send/receive buffer.
+	DefaultMaxBufferSize = 4 << 20 // 4 MiB
+)
+
+// SendBufferSizeOption is used by stack.(Stack*).Option/SetOption to
+// get/set the default, min and max send buffer sizes.
+type SendBufferSizeOption struct {
+	Min     int
+	Default int
+	Max     int
+}
+
+// ReceiveBufferSizeOption is used by stack.(Stack*).Option/SetOption to
+// get/set the default, min and max receive buffer sizes.
+type ReceiveBufferSizeOption struct {
+	Min     int
+	Default int
+	Max     int
+}
+
+// SetOption allows setting stack wide options.
+func (s *Stack) SetOption(option interface{}) *tcpip.Error {
+	switch v := option.(type) {
+	case SendBufferSizeOption:
+		// Make sure we don't allow lowering the buffer below minimum
+		// required for stack to work.
+		if v.Min < MinBufferSize {
+			return tcpip.ErrInvalidOptionValue
+		}
+
+		if v.Default < v.Min || v.Default > v.Max {
+			return tcpip.ErrInvalidOptionValue
+		}
+
+		s.mu.Lock()
+		s.sendBufferSize = v
+		s.mu.Unlock()
+		return nil
+
+	case ReceiveBufferSizeOption:
+		// Make sure we don't allow lowering the buffer below minimum
+		// required for stack to work.
+		if v.Min < MinBufferSize {
+			return tcpip.ErrInvalidOptionValue
+		}
+
+		if v.Default < v.Min || v.Default > v.Max {
+			return tcpip.ErrInvalidOptionValue
+		}
+
+		s.mu.Lock()
+		s.receiveBufferSize = v
+		s.mu.Unlock()
+		return nil
+
+	default:
+		return tcpip.ErrUnknownProtocolOption
+	}
+}
+
+// Option allows retrieving stack wide options.
+func (s *Stack) Option(option interface{}) *tcpip.Error {
+	switch v := option.(type) {
+	case *SendBufferSizeOption:
+		s.mu.RLock()
+		*v = s.sendBufferSize
+		s.mu.RUnlock()
+		return nil
+
+	case *ReceiveBufferSizeOption:
+		s.mu.RLock()
+		*v = s.receiveBufferSize
+		s.mu.RUnlock()
+		return nil
+
+	default:
+		return tcpip.ErrUnknownProtocolOption
+	}
+}