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ipv6: add {Read,Write}Batch methods to PacketConn
This change provides message IO functionality that may support the construction of modern datagram transport protocols. The modern datagram transport protocols on a multihomed node basically need to control each packet path for traffic engineering by using information belongs to network- or link-layer implementation. In addtion, it's desirable to be able to do simultaneous transmission across multiple network- or link-layer adjacencies wihtout any additional cost. The ReadBatch and WriteBatch methods of PacketConn can be used to read and write an IO message that contains the information of network- or link-layer implementation, and read and write a batch of IO messages on Linux. The Marshal and Parse methods of ControlMessage can help to marshal and parse information contained in IO messages. Updates golang/go#3661. Change-Id: I94484e2e135f4969ddf5c2548bf6be0cc16888bf Reviewed-on: https://go-review.googlesource.com/38276 Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,119 @@ | ||
| // Copyright 2017 The Go Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style | ||
| // license that can be found in the LICENSE file. | ||
|
|
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| // +build go1.9 | ||
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| package ipv6 | ||
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|
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| import ( | ||
| "net" | ||
| "runtime" | ||
| "syscall" | ||
|
|
||
| "golang.org/x/net/internal/socket" | ||
| ) | ||
|
|
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| // BUG(mikio): On Windows, the ReadBatch and WriteBatch methods of | ||
| // PacketConn are not implemented. | ||
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|
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| // A Message represents an IO message. | ||
| // | ||
| // type Message struct { | ||
| // Buffers [][]byte | ||
| // OOB []byte | ||
| // Addr net.Addr | ||
| // N int | ||
| // NN int | ||
| // Flags int | ||
| // } | ||
| // | ||
| // The Buffers fields represents a list of contiguous buffers, which | ||
| // can be used for vectored IO, for example, putting a header and a | ||
| // payload in each slice. | ||
| // When writing, the Buffers field must contain at least one byte to | ||
| // write. | ||
| // When reading, the Buffers field will always contain a byte to read. | ||
| // | ||
| // The OOB field contains protocol-specific control or miscellaneous | ||
| // ancillary data known as out-of-band data. | ||
| // It can be nil when not required. | ||
| // | ||
| // The Addr field specifies a destination address when writing. | ||
| // It can be nil when the underlying protocol of the endpoint uses | ||
| // connection-oriented communication. | ||
| // After a successful read, it may contain the source address on the | ||
| // received packet. | ||
| // | ||
| // The N field indicates the number of bytes read or written from/to | ||
| // Buffers. | ||
| // | ||
| // The NN field indicates the number of bytes read or written from/to | ||
| // OOB. | ||
| // | ||
| // The Flags field contains protocol-specific information on the | ||
| // received message. | ||
| type Message = socket.Message | ||
|
|
||
| // ReadBatch reads a batch of messages. | ||
| // | ||
| // The provided flags is a set of platform-dependent flags, such as | ||
| // syscall.MSG_PEEK. | ||
| // | ||
| // On a successful read it returns the number of messages received, up | ||
| // to len(ms). | ||
| // | ||
| // On Linux, a batch read will be optimized. | ||
| // On other platforms, this method will read only a single message. | ||
| func (c *payloadHandler) ReadBatch(ms []Message, flags int) (int, error) { | ||
| if !c.ok() { | ||
| return 0, syscall.EINVAL | ||
| } | ||
| switch runtime.GOOS { | ||
| case "linux": | ||
| n, err := c.RecvMsgs([]socket.Message(ms), flags) | ||
| if err != nil { | ||
| err = &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err} | ||
| } | ||
| return n, err | ||
| default: | ||
| n := 1 | ||
| err := c.RecvMsg(&ms[0], flags) | ||
| if err != nil { | ||
| n = 0 | ||
| err = &net.OpError{Op: "read", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err} | ||
| } | ||
| return n, err | ||
| } | ||
| } | ||
|
|
||
| // WriteBatch writes a batch of messages. | ||
| // | ||
| // The provided flags is a set of platform-dependent flags, such as | ||
| // syscall.MSG_DONTROUTE. | ||
| // | ||
| // It returns the number of messages written on a successful write. | ||
| // | ||
| // On Linux, a batch write will be optimized. | ||
| // On other platforms, this method will write only a single message. | ||
| func (c *payloadHandler) WriteBatch(ms []Message, flags int) (int, error) { | ||
| if !c.ok() { | ||
| return 0, syscall.EINVAL | ||
| } | ||
| switch runtime.GOOS { | ||
| case "linux": | ||
| n, err := c.SendMsgs([]socket.Message(ms), flags) | ||
| if err != nil { | ||
| err = &net.OpError{Op: "write", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err} | ||
| } | ||
| return n, err | ||
| default: | ||
| n := 1 | ||
| err := c.SendMsg(&ms[0], flags) | ||
| if err != nil { | ||
| n = 0 | ||
| err = &net.OpError{Op: "write", Net: c.PacketConn.LocalAddr().Network(), Source: c.PacketConn.LocalAddr(), Err: err} | ||
| } | ||
| return n, err | ||
| } | ||
| } |
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