| 1 | // Package protocol implements the wire envelope and codec for the netipc |
| 2 | // protocol. Pure byte-layout encode/decode. No I/O, no transport, no |
| 3 | // allocation on decode. Localhost-only IPC — all multi-byte fields use |
| 4 | // host byte order. |
| 5 | // |
| 6 | // Decoded "View" types borrow the underlying buffer and are valid only while |
| 7 | // that buffer lives. Copy immediately if the data is needed later. |
| 8 | package protocol |
| 9 | |
| 10 | import ( |
| 11 | "encoding/binary" |
| 12 | "errors" |
| 13 | ) |
| 14 | |
| 15 | // --------------------------------------------------------------------------- |
| 16 | // Constants |
| 17 | // --------------------------------------------------------------------------- |
| 18 | |
| 19 | const ( |
| 20 | MagicMsg uint32 = 0x4e495043 // "NIPC" |
| 21 | MagicChunk uint32 = 0x4e43484b // "NCHK" |
| 22 | Version uint16 = 1 |
| 23 | HeaderLen uint16 = 32 |
| 24 | HeaderSize = 32 |
| 25 | |
| 26 | // Message kinds. |
| 27 | KindRequest uint16 = 1 |
| 28 | KindResponse uint16 = 2 |
| 29 | KindControl uint16 = 3 |
| 30 | |
| 31 | // Flags. |
| 32 | FlagBatch uint16 = 0x0001 |
| 33 | |
| 34 | // Transport status. |
| 35 | StatusOK uint16 = 0 |
| 36 | StatusBadEnvelope uint16 = 1 |
| 37 | StatusAuthFailed uint16 = 2 |
| 38 | StatusIncompatible uint16 = 3 |
| 39 | StatusUnsupported uint16 = 4 |
| 40 | StatusLimitExceeded uint16 = 5 |
| 41 | StatusInternalError uint16 = 6 |
| 42 | |
| 43 | // Control opcodes. |
| 44 | CodeHello uint16 = 1 |
| 45 | CodeHelloAck uint16 = 2 |
| 46 | |
| 47 | // Method codes. |
| 48 | MethodIncrement uint16 = 1 |
| 49 | MethodCgroupsSnapshot uint16 = 2 |
| 50 | MethodStringReverse uint16 = 3 |
| 51 | MethodCgroupsLookup uint16 = 4 |
| 52 | MethodAppsLookup uint16 = 5 |
| 53 | |
| 54 | // Profile bits. |
| 55 | ProfileBaseline uint32 = 0x01 |
| 56 | ProfileSHMHybrid uint32 = 0x02 |
| 57 | ProfileSHMFutex uint32 = 0x04 |
| 58 | ProfileSHMWaitAddr uint32 = 0x08 |
| 59 | |
| 60 | // Defaults. |
| 61 | MaxPayloadDefault uint32 = 1024 |
| 62 | |
| 63 | // MaxPayloadCap is the hard cap on negotiated request payload sizes |
| 64 | // (1 MiB) to prevent excessive memory allocation from a compromised peer. |
| 65 | MaxPayloadCap uint32 = 1024 * 1024 |
| 66 | |
| 67 | // Alignment for batch items and typed codec items. |
| 68 | Alignment = 8 |
| 69 | |
| 70 | // Payload sizes. |
| 71 | helloSize = 44 |
| 72 | helloAckSize = 48 |
| 73 | ) |
| 74 | |
| 75 | var ne = binary.NativeEndian |
| 76 | |
| 77 | // --------------------------------------------------------------------------- |
| 78 | // Errors |
| 79 | // --------------------------------------------------------------------------- |
| 80 | |
| 81 | var ( |
| 82 | ErrTruncated = errors.New("buffer too short") |
| 83 | ErrBadMagic = errors.New("magic value mismatch") |
| 84 | ErrBadVersion = errors.New("unsupported version") |
| 85 | ErrBadHeaderLen = errors.New("header_len != 32") |
| 86 | ErrBadKind = errors.New("unknown message kind") |
| 87 | ErrBadLayout = errors.New("unknown layout_version") |
| 88 | ErrOutOfBounds = errors.New("offset+length exceeds data") |
| 89 | ErrMissingNul = errors.New("string not NUL-terminated") |
| 90 | ErrBadAlignment = errors.New("item not 8-byte aligned") |
| 91 | ErrBadItemCount = errors.New("item count inconsistent") |
| 92 | ErrOverflow = errors.New("builder out of space") |
| 93 | ) |
| 94 | |
| 95 | // --------------------------------------------------------------------------- |
| 96 | // Utility |
| 97 | // --------------------------------------------------------------------------- |
| 98 | |
| 99 | // Align8 rounds v up to the next multiple of 8. |
| 100 | func Align8(v int) int { |
| 101 | return (v + 7) &^ 7 |
| 102 | } |
| 103 | |
| 104 | // --------------------------------------------------------------------------- |
| 105 | // Outer message header (32 bytes) |
| 106 | // --------------------------------------------------------------------------- |
| 107 | |
| 108 | // Header is the outer message header (32 bytes on the wire). |
| 109 | type Header struct { |
| 110 | Magic uint32 |
| 111 | Version uint16 |
| 112 | HeaderLen uint16 |
| 113 | Kind uint16 |
| 114 | Flags uint16 |
| 115 | Code uint16 |
| 116 | TransportStatus uint16 |
| 117 | PayloadLen uint32 |
| 118 | ItemCount uint32 |
| 119 | MessageID uint64 |
| 120 | } |
| 121 | |
| 122 | // Encode writes the header into buf. Returns 32 on success, 0 if buf is |
| 123 | // too small. |
| 124 | func (h *Header) Encode(buf []byte) int { |
| 125 | if len(buf) < HeaderSize { |
| 126 | return 0 |
| 127 | } |
| 128 | ne.PutUint32(buf[0:4], h.Magic) |
| 129 | ne.PutUint16(buf[4:6], h.Version) |
| 130 | ne.PutUint16(buf[6:8], h.HeaderLen) |
| 131 | ne.PutUint16(buf[8:10], h.Kind) |
| 132 | ne.PutUint16(buf[10:12], h.Flags) |
| 133 | ne.PutUint16(buf[12:14], h.Code) |
| 134 | ne.PutUint16(buf[14:16], h.TransportStatus) |
| 135 | ne.PutUint32(buf[16:20], h.PayloadLen) |
| 136 | ne.PutUint32(buf[20:24], h.ItemCount) |
| 137 | ne.PutUint64(buf[24:32], h.MessageID) |
| 138 | return HeaderSize |
| 139 | } |
| 140 | |
| 141 | // DecodeHeader decodes an outer message header from buf. Validates magic, |
| 142 | // version, header_len, and kind. |
| 143 | func DecodeHeader(buf []byte) (Header, error) { |
| 144 | if len(buf) < HeaderSize { |
| 145 | return Header{}, ErrTruncated |
| 146 | } |
| 147 | h := Header{ |
| 148 | Magic: ne.Uint32(buf[0:4]), |
| 149 | Version: ne.Uint16(buf[4:6]), |
| 150 | HeaderLen: ne.Uint16(buf[6:8]), |
| 151 | Kind: ne.Uint16(buf[8:10]), |
| 152 | Flags: ne.Uint16(buf[10:12]), |
| 153 | Code: ne.Uint16(buf[12:14]), |
| 154 | TransportStatus: ne.Uint16(buf[14:16]), |
| 155 | PayloadLen: ne.Uint32(buf[16:20]), |
| 156 | ItemCount: ne.Uint32(buf[20:24]), |
| 157 | MessageID: ne.Uint64(buf[24:32]), |
| 158 | } |
| 159 | if h.Magic != MagicMsg { |
| 160 | return Header{}, ErrBadMagic |
| 161 | } |
| 162 | if h.Version != Version { |
| 163 | return Header{}, ErrBadVersion |
| 164 | } |
| 165 | if h.HeaderLen != HeaderLen { |
| 166 | return Header{}, ErrBadHeaderLen |
| 167 | } |
| 168 | if h.Kind < KindRequest || h.Kind > KindControl { |
| 169 | return Header{}, ErrBadKind |
| 170 | } |
| 171 | return h, nil |
| 172 | } |
| 173 | |
| 174 | // --------------------------------------------------------------------------- |
| 175 | // Chunk continuation header (32 bytes) |
| 176 | // --------------------------------------------------------------------------- |
| 177 | |
| 178 | // ChunkHeader is a chunk continuation header (32 bytes on the wire). |
| 179 | type ChunkHeader struct { |
| 180 | Magic uint32 |
| 181 | Version uint16 |
| 182 | Flags uint16 |
| 183 | MessageID uint64 |
| 184 | TotalMessageLen uint32 |
| 185 | ChunkIndex uint32 |
| 186 | ChunkCount uint32 |
| 187 | ChunkPayloadLen uint32 |
| 188 | } |
| 189 | |
| 190 | // Encode writes the chunk header into buf. Returns 32 on success, 0 if |
| 191 | // buf is too small. |
| 192 | func (c *ChunkHeader) Encode(buf []byte) int { |
| 193 | if len(buf) < HeaderSize { |
| 194 | return 0 |
| 195 | } |
| 196 | ne.PutUint32(buf[0:4], c.Magic) |
| 197 | ne.PutUint16(buf[4:6], c.Version) |
| 198 | ne.PutUint16(buf[6:8], c.Flags) |
| 199 | ne.PutUint64(buf[8:16], c.MessageID) |
| 200 | ne.PutUint32(buf[16:20], c.TotalMessageLen) |
| 201 | ne.PutUint32(buf[20:24], c.ChunkIndex) |
| 202 | ne.PutUint32(buf[24:28], c.ChunkCount) |
| 203 | ne.PutUint32(buf[28:32], c.ChunkPayloadLen) |
| 204 | return HeaderSize |
| 205 | } |
| 206 | |
| 207 | // DecodeChunkHeader decodes a chunk continuation header from buf. |
| 208 | // Validates magic and version. |
| 209 | func DecodeChunkHeader(buf []byte) (ChunkHeader, error) { |
| 210 | if len(buf) < HeaderSize { |
| 211 | return ChunkHeader{}, ErrTruncated |
| 212 | } |
| 213 | c := ChunkHeader{ |
| 214 | Magic: ne.Uint32(buf[0:4]), |
| 215 | Version: ne.Uint16(buf[4:6]), |
| 216 | Flags: ne.Uint16(buf[6:8]), |
| 217 | MessageID: ne.Uint64(buf[8:16]), |
| 218 | TotalMessageLen: ne.Uint32(buf[16:20]), |
| 219 | ChunkIndex: ne.Uint32(buf[20:24]), |
| 220 | ChunkCount: ne.Uint32(buf[24:28]), |
| 221 | ChunkPayloadLen: ne.Uint32(buf[28:32]), |
| 222 | } |
| 223 | if c.Magic != MagicChunk { |
| 224 | return ChunkHeader{}, ErrBadMagic |
| 225 | } |
| 226 | if c.Version != Version { |
| 227 | return ChunkHeader{}, ErrBadVersion |
| 228 | } |
| 229 | if c.Flags != 0 { |
| 230 | return ChunkHeader{}, ErrBadLayout |
| 231 | } |
| 232 | if c.ChunkPayloadLen == 0 { |
| 233 | return ChunkHeader{}, ErrBadLayout |
| 234 | } |
| 235 | return c, nil |
| 236 | } |
| 237 | |
| 238 | // --------------------------------------------------------------------------- |
| 239 | // Batch item directory |
| 240 | // --------------------------------------------------------------------------- |
| 241 | |
| 242 | // BatchEntry is one entry in a batch item directory (8 bytes on wire). |
| 243 | type BatchEntry struct { |
| 244 | Offset uint32 |
| 245 | Length uint32 |
| 246 | } |
| 247 | |
| 248 | // BatchDirEncode encodes entries into buf. Returns total bytes written |
| 249 | // (len(entries) * 8), or 0 if buf is too small. |
| 250 | func BatchDirEncode(entries []BatchEntry, buf []byte) int { |
| 251 | need := len(entries) * 8 |
| 252 | if len(buf) < need { |
| 253 | return 0 |
| 254 | } |
| 255 | for i, e := range entries { |
| 256 | base := i * 8 |
| 257 | ne.PutUint32(buf[base:base+4], e.Offset) |
| 258 | ne.PutUint32(buf[base+4:base+8], e.Length) |
| 259 | } |
| 260 | return need |
| 261 | } |
| 262 | |
| 263 | // BatchDirDecode decodes itemCount directory entries from buf. Validates |
| 264 | // alignment and that each entry falls within packedAreaLen. |
| 265 | func BatchDirDecode(buf []byte, itemCount uint32, packedAreaLen uint32) ([]BatchEntry, error) { |
| 266 | count, ok := checkedInt(uint64(itemCount)) |
| 267 | if !ok { |
| 268 | return nil, ErrBadItemCount |
| 269 | } |
| 270 | dirSize, ok := checkedMulInt(count, 8) |
| 271 | if !ok { |
| 272 | return nil, ErrBadItemCount |
| 273 | } |
| 274 | if len(buf) < dirSize { |
| 275 | return nil, ErrTruncated |
| 276 | } |
| 277 | |
| 278 | out := make([]BatchEntry, count) |
| 279 | for i := range count { |
| 280 | base := i * 8 |
| 281 | off := ne.Uint32(buf[base : base+4]) |
| 282 | length := ne.Uint32(buf[base+4 : base+8]) |
| 283 | |
| 284 | if off%uint32(Alignment) != 0 { |
| 285 | return nil, ErrBadAlignment |
| 286 | } |
| 287 | if uint64(off)+uint64(length) > uint64(packedAreaLen) { |
| 288 | return nil, ErrOutOfBounds |
| 289 | } |
| 290 | out[i] = BatchEntry{Offset: off, Length: length} |
| 291 | } |
| 292 | return out, nil |
| 293 | } |
| 294 | |
| 295 | // BatchDirValidate validates the batch directory without allocating. |
| 296 | // Checks alignment and that each entry falls within packedAreaLen. |
| 297 | func BatchDirValidate(buf []byte, itemCount uint32, packedAreaLen uint32) error { |
| 298 | count, ok := checkedInt(uint64(itemCount)) |
| 299 | if !ok { |
| 300 | return ErrBadItemCount |
| 301 | } |
| 302 | dirSize, ok := checkedMulInt(count, 8) |
| 303 | if !ok { |
| 304 | return ErrBadItemCount |
| 305 | } |
| 306 | if len(buf) < dirSize { |
| 307 | return ErrTruncated |
| 308 | } |
| 309 | for i := range count { |
| 310 | base := i * 8 |
| 311 | off := ne.Uint32(buf[base : base+4]) |
| 312 | length := ne.Uint32(buf[base+4 : base+8]) |
| 313 | if off%uint32(Alignment) != 0 { |
| 314 | return ErrBadAlignment |
| 315 | } |
| 316 | if uint64(off)+uint64(length) > uint64(packedAreaLen) { |
| 317 | return ErrOutOfBounds |
| 318 | } |
| 319 | } |
| 320 | return nil |
| 321 | } |
| 322 | |
| 323 | // BatchItemGet extracts a single batch item by index from a complete batch |
| 324 | // payload. Returns the item slice on success. |
| 325 | func BatchItemGet(payload []byte, itemCount uint32, index uint32) ([]byte, error) { |
| 326 | if index >= itemCount { |
| 327 | return nil, ErrOutOfBounds |
| 328 | } |
| 329 | |
| 330 | dirSize, ok := checkedInt(uint64(itemCount) * 8) |
| 331 | if !ok { |
| 332 | return nil, ErrBadItemCount |
| 333 | } |
| 334 | dirAligned, ok := checkedAlign8(dirSize) |
| 335 | if !ok { |
| 336 | return nil, ErrBadItemCount |
| 337 | } |
| 338 | |
| 339 | if len(payload) < dirAligned { |
| 340 | return nil, ErrTruncated |
| 341 | } |
| 342 | |
| 343 | idx, ok := checkedInt(uint64(index)) |
| 344 | if !ok { |
| 345 | return nil, ErrOutOfBounds |
| 346 | } |
| 347 | base, ok := checkedMulInt(idx, 8) |
| 348 | if !ok { |
| 349 | return nil, ErrOutOfBounds |
| 350 | } |
| 351 | off, err := checkedWireU32Int(payload, base) |
| 352 | if err != nil { |
| 353 | return nil, err |
| 354 | } |
| 355 | length, err := checkedWireU32Int(payload, base+4) |
| 356 | if err != nil { |
| 357 | return nil, err |
| 358 | } |
| 359 | |
| 360 | packedAreaStart := dirAligned |
| 361 | packedAreaLen := len(payload) - packedAreaStart |
| 362 | |
| 363 | if off%Alignment != 0 { |
| 364 | return nil, ErrBadAlignment |
| 365 | } |
| 366 | relEnd, ok := checkedAddInt(off, length) |
| 367 | if !ok || relEnd > packedAreaLen { |
| 368 | return nil, ErrOutOfBounds |
| 369 | } |
| 370 | |
| 371 | start, ok := checkedAddInt(packedAreaStart, off) |
| 372 | if !ok { |
| 373 | return nil, ErrOutOfBounds |
| 374 | } |
| 375 | end, ok := checkedAddInt(start, length) |
| 376 | if !ok { |
| 377 | return nil, ErrOutOfBounds |
| 378 | } |
| 379 | return payload[start:end], nil |
| 380 | } |
| 381 | |
| 382 | // --------------------------------------------------------------------------- |
| 383 | // Batch builder |
| 384 | // --------------------------------------------------------------------------- |
| 385 | |
| 386 | // BatchBuilder builds a batch payload: [directory] [align-pad] [packed items]. |
| 387 | type BatchBuilder struct { |
| 388 | buf []byte |
| 389 | itemCount uint32 |
| 390 | maxItems uint32 |
| 391 | dirEnd int // byte offset where directory reservation ends |
| 392 | dataOffset int // current offset within the packed data area (relative) |
| 393 | } |
| 394 | |
| 395 | // Reset reinitializes a batch builder against a caller-provided buffer. |
| 396 | // This lets hot paths reuse stack-allocated builders instead of allocating |
| 397 | // a fresh helper object for every request. |
| 398 | func (b *BatchBuilder) Reset(buf []byte, maxItems uint32) { |
| 399 | b.buf = buf |
| 400 | b.itemCount = 0 |
| 401 | b.maxItems = maxItems |
| 402 | dirSize, ok := checkedInt(uint64(maxItems) * 8) |
| 403 | if !ok { |
| 404 | b.dirEnd = maxIntValue() |
| 405 | b.dataOffset = 0 |
| 406 | return |
| 407 | } |
| 408 | dirEnd, ok := checkedAlign8(dirSize) |
| 409 | if !ok { |
| 410 | b.dirEnd = maxIntValue() |
| 411 | b.dataOffset = 0 |
| 412 | return |
| 413 | } |
| 414 | b.dirEnd = dirEnd |
| 415 | b.dataOffset = 0 |
| 416 | } |
| 417 | |
| 418 | // NewBatchBuilder creates a new batch builder. buf must be large enough for |
| 419 | // maxItems*8 (directory) + packed data. |
| 420 | func NewBatchBuilder(buf []byte, maxItems uint32) *BatchBuilder { |
| 421 | b := &BatchBuilder{} |
| 422 | b.Reset(buf, maxItems) |
| 423 | return b |
| 424 | } |
| 425 | |
| 426 | // Add appends an item payload. Handles alignment padding. |
| 427 | func (b *BatchBuilder) Add(item []byte) error { |
| 428 | if b.itemCount >= b.maxItems { |
| 429 | return ErrOverflow |
| 430 | } |
| 431 | |
| 432 | alignedOff, ok := checkedAlign8(b.dataOffset) |
| 433 | if !ok { |
| 434 | return ErrOverflow |
| 435 | } |
| 436 | absPos, ok := checkedAddInt(b.dirEnd, alignedOff) |
| 437 | if !ok { |
| 438 | return ErrOverflow |
| 439 | } |
| 440 | |
| 441 | itemEnd, ok := checkedAddInt(absPos, len(item)) |
| 442 | if !ok || itemEnd > len(b.buf) { |
| 443 | return ErrOverflow |
| 444 | } |
| 445 | |
| 446 | // Zero alignment padding. |
| 447 | if alignedOff > b.dataOffset { |
| 448 | padStart, ok := checkedAddInt(b.dirEnd, b.dataOffset) |
| 449 | if !ok { |
| 450 | return ErrOverflow |
| 451 | } |
| 452 | padEnd, ok := checkedAddInt(b.dirEnd, alignedOff) |
| 453 | if !ok { |
| 454 | return ErrOverflow |
| 455 | } |
| 456 | clear(b.buf[padStart:padEnd]) |
| 457 | } |
| 458 | |
| 459 | copy(b.buf[absPos:], item) |
| 460 | |
| 461 | // Write directory entry. |
| 462 | idx, ok := checkedInt(uint64(b.itemCount) * 8) |
| 463 | if !ok { |
| 464 | return ErrOverflow |
| 465 | } |
| 466 | alignedOff32, ok := checkedU32Int(alignedOff) |
| 467 | if !ok { |
| 468 | return ErrOverflow |
| 469 | } |
| 470 | itemLen32, ok := checkedU32Int(len(item)) |
| 471 | if !ok { |
| 472 | return ErrOverflow |
| 473 | } |
| 474 | ne.PutUint32(b.buf[idx:idx+4], alignedOff32) |
| 475 | ne.PutUint32(b.buf[idx+4:idx+8], itemLen32) |
| 476 | |
| 477 | b.dataOffset, ok = checkedAddInt(alignedOff, len(item)) |
| 478 | if !ok { |
| 479 | return ErrOverflow |
| 480 | } |
| 481 | b.itemCount++ |
| 482 | return nil |
| 483 | } |
| 484 | |
| 485 | // Finish finalizes the batch. Returns (totalPayloadSize, itemCount). |
| 486 | // Compacts if fewer items were added than maxItems. |
| 487 | func (b *BatchBuilder) Finish() (int, uint32) { |
| 488 | count := b.itemCount |
| 489 | dirSize, ok := checkedInt(uint64(count) * 8) |
| 490 | if !ok { |
| 491 | return 0, count |
| 492 | } |
| 493 | finalDirAligned, ok := checkedAlign8(dirSize) |
| 494 | if !ok { |
| 495 | return 0, count |
| 496 | } |
| 497 | |
| 498 | if finalDirAligned < b.dirEnd && b.dataOffset > 0 { |
| 499 | dataEnd, ok := checkedAddInt(b.dirEnd, b.dataOffset) |
| 500 | if !ok { |
| 501 | return 0, count |
| 502 | } |
| 503 | // Shift packed data left. |
| 504 | copy(b.buf[finalDirAligned:], b.buf[b.dirEnd:dataEnd]) |
| 505 | } |
| 506 | |
| 507 | alignedData, ok := checkedAlign8(b.dataOffset) |
| 508 | if !ok { |
| 509 | return 0, count |
| 510 | } |
| 511 | total, ok := checkedAddInt(finalDirAligned, alignedData) |
| 512 | if !ok { |
| 513 | return 0, count |
| 514 | } |
| 515 | return total, count |
| 516 | } |
| 517 | |
| 518 | // --------------------------------------------------------------------------- |
| 519 | // Hello payload (44 bytes) |
| 520 | // --------------------------------------------------------------------------- |
| 521 | |
| 522 | // Hello is the client handshake payload (44 bytes on the wire). |
| 523 | type Hello struct { |
| 524 | LayoutVersion uint16 |
| 525 | Flags uint16 |
| 526 | SupportedProfiles uint32 |
| 527 | PreferredProfiles uint32 |
| 528 | MaxRequestPayloadBytes uint32 |
| 529 | MaxRequestBatchItems uint32 |
| 530 | MaxResponsePayloadBytes uint32 |
| 531 | MaxResponseBatchItems uint32 |
| 532 | AuthToken uint64 |
| 533 | PacketSize uint32 |
| 534 | } |
| 535 | |
| 536 | // Encode writes the Hello payload into buf. Returns 44 on success, 0 if |
| 537 | // buf is too small. |
| 538 | func (h *Hello) Encode(buf []byte) int { |
| 539 | if len(buf) < helloSize { |
| 540 | return 0 |
| 541 | } |
| 542 | ne.PutUint16(buf[0:2], h.LayoutVersion) |
| 543 | ne.PutUint16(buf[2:4], h.Flags) |
| 544 | ne.PutUint32(buf[4:8], h.SupportedProfiles) |
| 545 | ne.PutUint32(buf[8:12], h.PreferredProfiles) |
| 546 | ne.PutUint32(buf[12:16], h.MaxRequestPayloadBytes) |
| 547 | ne.PutUint32(buf[16:20], h.MaxRequestBatchItems) |
| 548 | ne.PutUint32(buf[20:24], h.MaxResponsePayloadBytes) |
| 549 | ne.PutUint32(buf[24:28], h.MaxResponseBatchItems) |
| 550 | ne.PutUint32(buf[28:32], 0) // padding |
| 551 | ne.PutUint64(buf[32:40], h.AuthToken) |
| 552 | ne.PutUint32(buf[40:44], h.PacketSize) |
| 553 | return helloSize |
| 554 | } |
| 555 | |
| 556 | // DecodeHello decodes a Hello payload from buf. Validates layout_version. |
| 557 | func DecodeHello(buf []byte) (Hello, error) { |
| 558 | if len(buf) < helloSize { |
| 559 | return Hello{}, ErrTruncated |
| 560 | } |
| 561 | h := Hello{ |
| 562 | LayoutVersion: ne.Uint16(buf[0:2]), |
| 563 | Flags: ne.Uint16(buf[2:4]), |
| 564 | SupportedProfiles: ne.Uint32(buf[4:8]), |
| 565 | PreferredProfiles: ne.Uint32(buf[8:12]), |
| 566 | MaxRequestPayloadBytes: ne.Uint32(buf[12:16]), |
| 567 | MaxRequestBatchItems: ne.Uint32(buf[16:20]), |
| 568 | MaxResponsePayloadBytes: ne.Uint32(buf[20:24]), |
| 569 | MaxResponseBatchItems: ne.Uint32(buf[24:28]), |
| 570 | // buf[28:32] is reserved padding, must be zero. |
| 571 | AuthToken: ne.Uint64(buf[32:40]), |
| 572 | PacketSize: ne.Uint32(buf[40:44]), |
| 573 | } |
| 574 | if h.LayoutVersion != 1 { |
| 575 | return Hello{}, ErrBadLayout |
| 576 | } |
| 577 | // Validate padding bytes 28..32 are zero |
| 578 | if ne.Uint32(buf[28:32]) != 0 { |
| 579 | return Hello{}, ErrBadLayout |
| 580 | } |
| 581 | return h, nil |
| 582 | } |
| 583 | |
| 584 | // --------------------------------------------------------------------------- |
| 585 | // Hello-ack payload (44 bytes) |
| 586 | // --------------------------------------------------------------------------- |
| 587 | |
| 588 | // HelloAck is the server handshake response payload (48 bytes on the wire). |
| 589 | type HelloAck struct { |
| 590 | LayoutVersion uint16 |
| 591 | Flags uint16 |
| 592 | ServerSupportedProfiles uint32 |
| 593 | IntersectionProfiles uint32 |
| 594 | SelectedProfile uint32 |
| 595 | AgreedMaxRequestPayloadBytes uint32 |
| 596 | AgreedMaxRequestBatchItems uint32 |
| 597 | AgreedMaxResponsePayloadBytes uint32 |
| 598 | AgreedMaxResponseBatchItems uint32 |
| 599 | AgreedPacketSize uint32 |
| 600 | SessionID uint64 |
| 601 | } |
| 602 | |
| 603 | // Encode writes the HelloAck payload into buf. Returns 48 on success, 0 |
| 604 | // if buf is too small. |
| 605 | func (h *HelloAck) Encode(buf []byte) int { |
| 606 | if len(buf) < helloAckSize { |
| 607 | return 0 |
| 608 | } |
| 609 | ne.PutUint16(buf[0:2], h.LayoutVersion) |
| 610 | ne.PutUint16(buf[2:4], h.Flags) |
| 611 | ne.PutUint32(buf[4:8], h.ServerSupportedProfiles) |
| 612 | ne.PutUint32(buf[8:12], h.IntersectionProfiles) |
| 613 | ne.PutUint32(buf[12:16], h.SelectedProfile) |
| 614 | ne.PutUint32(buf[16:20], h.AgreedMaxRequestPayloadBytes) |
| 615 | ne.PutUint32(buf[20:24], h.AgreedMaxRequestBatchItems) |
| 616 | ne.PutUint32(buf[24:28], h.AgreedMaxResponsePayloadBytes) |
| 617 | ne.PutUint32(buf[28:32], h.AgreedMaxResponseBatchItems) |
| 618 | ne.PutUint32(buf[32:36], h.AgreedPacketSize) |
| 619 | ne.PutUint32(buf[36:40], 0) // padding |
| 620 | ne.PutUint64(buf[40:48], h.SessionID) |
| 621 | return helloAckSize |
| 622 | } |
| 623 | |
| 624 | // DecodeHelloAck decodes a HelloAck payload from buf. Validates |
| 625 | // layout_version. |
| 626 | func DecodeHelloAck(buf []byte) (HelloAck, error) { |
| 627 | if len(buf) < helloAckSize { |
| 628 | return HelloAck{}, ErrTruncated |
| 629 | } |
| 630 | h := HelloAck{ |
| 631 | LayoutVersion: ne.Uint16(buf[0:2]), |
| 632 | Flags: ne.Uint16(buf[2:4]), |
| 633 | ServerSupportedProfiles: ne.Uint32(buf[4:8]), |
| 634 | IntersectionProfiles: ne.Uint32(buf[8:12]), |
| 635 | SelectedProfile: ne.Uint32(buf[12:16]), |
| 636 | AgreedMaxRequestPayloadBytes: ne.Uint32(buf[16:20]), |
| 637 | AgreedMaxRequestBatchItems: ne.Uint32(buf[20:24]), |
| 638 | AgreedMaxResponsePayloadBytes: ne.Uint32(buf[24:28]), |
| 639 | AgreedMaxResponseBatchItems: ne.Uint32(buf[28:32]), |
| 640 | AgreedPacketSize: ne.Uint32(buf[32:36]), |
| 641 | // skip padding at 36:40 |
| 642 | SessionID: ne.Uint64(buf[40:48]), |
| 643 | } |
| 644 | if h.LayoutVersion != 1 { |
| 645 | return HelloAck{}, ErrBadLayout |
| 646 | } |
| 647 | if h.Flags != 0 { |
| 648 | return HelloAck{}, ErrBadLayout |
| 649 | } |
| 650 | return h, nil |
| 651 | } |