David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame] | 1 | // Copyright 2017 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // Package socket provides a portable interface for socket system |
| 6 | // calls. |
| 7 | package socket // import "golang.org/x/net/internal/socket" |
| 8 | |
| 9 | import ( |
| 10 | "errors" |
| 11 | "net" |
| 12 | "unsafe" |
| 13 | ) |
| 14 | |
| 15 | // An Option represents a sticky socket option. |
| 16 | type Option struct { |
| 17 | Level int // level |
| 18 | Name int // name; must be equal or greater than 1 |
| 19 | Len int // length of value in bytes; must be equal or greater than 1 |
| 20 | } |
| 21 | |
| 22 | // Get reads a value for the option from the kernel. |
| 23 | // It returns the number of bytes written into b. |
| 24 | func (o *Option) Get(c *Conn, b []byte) (int, error) { |
| 25 | if o.Name < 1 || o.Len < 1 { |
| 26 | return 0, errors.New("invalid option") |
| 27 | } |
| 28 | if len(b) < o.Len { |
| 29 | return 0, errors.New("short buffer") |
| 30 | } |
| 31 | return o.get(c, b) |
| 32 | } |
| 33 | |
| 34 | // GetInt returns an integer value for the option. |
| 35 | // |
| 36 | // The Len field of Option must be either 1 or 4. |
| 37 | func (o *Option) GetInt(c *Conn) (int, error) { |
| 38 | if o.Len != 1 && o.Len != 4 { |
| 39 | return 0, errors.New("invalid option") |
| 40 | } |
| 41 | var b []byte |
| 42 | var bb [4]byte |
| 43 | if o.Len == 1 { |
| 44 | b = bb[:1] |
| 45 | } else { |
| 46 | b = bb[:4] |
| 47 | } |
| 48 | n, err := o.get(c, b) |
| 49 | if err != nil { |
| 50 | return 0, err |
| 51 | } |
| 52 | if n != o.Len { |
| 53 | return 0, errors.New("invalid option length") |
| 54 | } |
| 55 | if o.Len == 1 { |
| 56 | return int(b[0]), nil |
| 57 | } |
| 58 | return int(NativeEndian.Uint32(b[:4])), nil |
| 59 | } |
| 60 | |
| 61 | // Set writes the option and value to the kernel. |
| 62 | func (o *Option) Set(c *Conn, b []byte) error { |
| 63 | if o.Name < 1 || o.Len < 1 { |
| 64 | return errors.New("invalid option") |
| 65 | } |
| 66 | if len(b) < o.Len { |
| 67 | return errors.New("short buffer") |
| 68 | } |
| 69 | return o.set(c, b) |
| 70 | } |
| 71 | |
| 72 | // SetInt writes the option and value to the kernel. |
| 73 | // |
| 74 | // The Len field of Option must be either 1 or 4. |
| 75 | func (o *Option) SetInt(c *Conn, v int) error { |
| 76 | if o.Len != 1 && o.Len != 4 { |
| 77 | return errors.New("invalid option") |
| 78 | } |
| 79 | var b []byte |
| 80 | if o.Len == 1 { |
| 81 | b = []byte{byte(v)} |
| 82 | } else { |
| 83 | var bb [4]byte |
| 84 | NativeEndian.PutUint32(bb[:o.Len], uint32(v)) |
| 85 | b = bb[:4] |
| 86 | } |
| 87 | return o.set(c, b) |
| 88 | } |
| 89 | |
| 90 | func controlHeaderLen() int { |
| 91 | return roundup(sizeofCmsghdr) |
| 92 | } |
| 93 | |
| 94 | func controlMessageLen(dataLen int) int { |
| 95 | return roundup(sizeofCmsghdr) + dataLen |
| 96 | } |
| 97 | |
| 98 | // ControlMessageSpace returns the whole length of control message. |
| 99 | func ControlMessageSpace(dataLen int) int { |
| 100 | return roundup(sizeofCmsghdr) + roundup(dataLen) |
| 101 | } |
| 102 | |
| 103 | // A ControlMessage represents the head message in a stream of control |
| 104 | // messages. |
| 105 | // |
| 106 | // A control message comprises of a header, data and a few padding |
| 107 | // fields to conform to the interface to the kernel. |
| 108 | // |
| 109 | // See RFC 3542 for further information. |
| 110 | type ControlMessage []byte |
| 111 | |
| 112 | // Data returns the data field of the control message at the head on |
| 113 | // w. |
| 114 | func (m ControlMessage) Data(dataLen int) []byte { |
| 115 | l := controlHeaderLen() |
| 116 | if len(m) < l || len(m) < l+dataLen { |
| 117 | return nil |
| 118 | } |
| 119 | return m[l : l+dataLen] |
| 120 | } |
| 121 | |
| 122 | // Next returns the control message at the next on w. |
| 123 | // |
| 124 | // Next works only for standard control messages. |
| 125 | func (m ControlMessage) Next(dataLen int) ControlMessage { |
| 126 | l := ControlMessageSpace(dataLen) |
| 127 | if len(m) < l { |
| 128 | return nil |
| 129 | } |
| 130 | return m[l:] |
| 131 | } |
| 132 | |
| 133 | // MarshalHeader marshals the header fields of the control message at |
| 134 | // the head on w. |
| 135 | func (m ControlMessage) MarshalHeader(lvl, typ, dataLen int) error { |
| 136 | if len(m) < controlHeaderLen() { |
| 137 | return errors.New("short message") |
| 138 | } |
| 139 | h := (*cmsghdr)(unsafe.Pointer(&m[0])) |
| 140 | h.set(controlMessageLen(dataLen), lvl, typ) |
| 141 | return nil |
| 142 | } |
| 143 | |
| 144 | // ParseHeader parses and returns the header fields of the control |
| 145 | // message at the head on w. |
| 146 | func (m ControlMessage) ParseHeader() (lvl, typ, dataLen int, err error) { |
| 147 | l := controlHeaderLen() |
| 148 | if len(m) < l { |
| 149 | return 0, 0, 0, errors.New("short message") |
| 150 | } |
| 151 | h := (*cmsghdr)(unsafe.Pointer(&m[0])) |
| 152 | return h.lvl(), h.typ(), int(uint64(h.len()) - uint64(l)), nil |
| 153 | } |
| 154 | |
| 155 | // Marshal marshals the control message at the head on w, and returns |
| 156 | // the next control message. |
| 157 | func (m ControlMessage) Marshal(lvl, typ int, data []byte) (ControlMessage, error) { |
| 158 | l := len(data) |
| 159 | if len(m) < ControlMessageSpace(l) { |
| 160 | return nil, errors.New("short message") |
| 161 | } |
| 162 | h := (*cmsghdr)(unsafe.Pointer(&m[0])) |
| 163 | h.set(controlMessageLen(l), lvl, typ) |
| 164 | if l > 0 { |
| 165 | copy(m.Data(l), data) |
| 166 | } |
| 167 | return m.Next(l), nil |
| 168 | } |
| 169 | |
| 170 | // Parse parses w as a single or multiple control messages. |
| 171 | // |
| 172 | // Parse works for both standard and compatible messages. |
| 173 | func (m ControlMessage) Parse() ([]ControlMessage, error) { |
| 174 | var ms []ControlMessage |
| 175 | for len(m) >= controlHeaderLen() { |
| 176 | h := (*cmsghdr)(unsafe.Pointer(&m[0])) |
| 177 | l := h.len() |
| 178 | if l <= 0 { |
| 179 | return nil, errors.New("invalid header length") |
| 180 | } |
| 181 | if uint64(l) < uint64(controlHeaderLen()) { |
| 182 | return nil, errors.New("invalid message length") |
| 183 | } |
| 184 | if uint64(l) > uint64(len(m)) { |
| 185 | return nil, errors.New("short buffer") |
| 186 | } |
| 187 | // On message reception: |
| 188 | // |
| 189 | // |<- ControlMessageSpace --------------->| |
| 190 | // |<- controlMessageLen ---------->| | |
| 191 | // |<- controlHeaderLen ->| | | |
| 192 | // +---------------+------+---------+------+ |
| 193 | // | Header | PadH | Data | PadD | |
| 194 | // +---------------+------+---------+------+ |
| 195 | // |
| 196 | // On compatible message reception: |
| 197 | // |
| 198 | // | ... |<- controlMessageLen ----------->| |
| 199 | // | ... |<- controlHeaderLen ->| | |
| 200 | // +-----+---------------+------+----------+ |
| 201 | // | ... | Header | PadH | Data | |
| 202 | // +-----+---------------+------+----------+ |
| 203 | ms = append(ms, ControlMessage(m[:l])) |
| 204 | ll := l - controlHeaderLen() |
| 205 | if len(m) >= ControlMessageSpace(ll) { |
| 206 | m = m[ControlMessageSpace(ll):] |
| 207 | } else { |
| 208 | m = m[controlMessageLen(ll):] |
| 209 | } |
| 210 | } |
| 211 | return ms, nil |
| 212 | } |
| 213 | |
| 214 | // NewControlMessage returns a new stream of control messages. |
| 215 | func NewControlMessage(dataLen []int) ControlMessage { |
| 216 | var l int |
| 217 | for i := range dataLen { |
| 218 | l += ControlMessageSpace(dataLen[i]) |
| 219 | } |
| 220 | return make([]byte, l) |
| 221 | } |
| 222 | |
| 223 | // A Message represents an IO message. |
| 224 | type Message struct { |
| 225 | // When writing, the Buffers field must contain at least one |
| 226 | // byte to write. |
| 227 | // When reading, the Buffers field will always contain a byte |
| 228 | // to read. |
| 229 | Buffers [][]byte |
| 230 | |
| 231 | // OOB contains protocol-specific control or miscellaneous |
| 232 | // ancillary data known as out-of-band data. |
| 233 | OOB []byte |
| 234 | |
| 235 | // Addr specifies a destination address when writing. |
| 236 | // It can be nil when the underlying protocol of the raw |
| 237 | // connection uses connection-oriented communication. |
| 238 | // After a successful read, it may contain the source address |
| 239 | // on the received packet. |
| 240 | Addr net.Addr |
| 241 | |
| 242 | N int // # of bytes read or written from/to Buffers |
| 243 | NN int // # of bytes read or written from/to OOB |
| 244 | Flags int // protocol-specific information on the received message |
| 245 | } |
| 246 | |
| 247 | // RecvMsg wraps recvmsg system call. |
| 248 | // |
| 249 | // The provided flags is a set of platform-dependent flags, such as |
| 250 | // syscall.MSG_PEEK. |
| 251 | func (c *Conn) RecvMsg(m *Message, flags int) error { |
| 252 | return c.recvMsg(m, flags) |
| 253 | } |
| 254 | |
| 255 | // SendMsg wraps sendmsg system call. |
| 256 | // |
| 257 | // The provided flags is a set of platform-dependent flags, such as |
| 258 | // syscall.MSG_DONTROUTE. |
| 259 | func (c *Conn) SendMsg(m *Message, flags int) error { |
| 260 | return c.sendMsg(m, flags) |
| 261 | } |
| 262 | |
| 263 | // RecvMsgs wraps recvmmsg system call. |
| 264 | // |
| 265 | // It returns the number of processed messages. |
| 266 | // |
| 267 | // The provided flags is a set of platform-dependent flags, such as |
| 268 | // syscall.MSG_PEEK. |
| 269 | // |
| 270 | // Only Linux supports this. |
| 271 | func (c *Conn) RecvMsgs(ms []Message, flags int) (int, error) { |
| 272 | return c.recvMsgs(ms, flags) |
| 273 | } |
| 274 | |
| 275 | // SendMsgs wraps sendmmsg system call. |
| 276 | // |
| 277 | // It returns the number of processed messages. |
| 278 | // |
| 279 | // The provided flags is a set of platform-dependent flags, such as |
| 280 | // syscall.MSG_DONTROUTE. |
| 281 | // |
| 282 | // Only Linux supports this. |
| 283 | func (c *Conn) SendMsgs(ms []Message, flags int) (int, error) { |
| 284 | return c.sendMsgs(ms, flags) |
| 285 | } |