| 502 | } |
| 503 | |
| 504 | struct onionpacket *create_onionpacket( |
| 505 | const tal_t *ctx, |
| 506 | struct sphinx_path *sp, |
| 507 | size_t fixed_size, |
| 508 | struct secret **path_secrets |
| 509 | ) |
| 510 | { |
| 511 | struct onionpacket *packet = talz(ctx, struct onionpacket); |
| 512 | int i, num_hops = tal_count(sp->hops); |
| 513 | size_t fillerSize = sphinx_path_payloads_size(sp) - |
| 514 | sphinx_hop_size(&sp->hops[num_hops - 1]); |
| 515 | u8 *filler; |
| 516 | struct keyset keys; |
| 517 | struct secret padkey; |
| 518 | struct hmac nexthmac; |
| 519 | struct hop_params *params; |
| 520 | struct secret *secrets = tal_arr(ctx, struct secret, num_hops); |
| 521 | size_t payloads_size = sphinx_path_payloads_size(sp); |
| 522 | size_t max_prefill = fixed_size - payloads_size; |
| 523 | |
| 524 | if (sphinx_path_payloads_size(sp) > fixed_size) { |
| 525 | tal_free(packet); |
| 526 | tal_free(secrets); |
| 527 | return NULL; |
| 528 | } |
| 529 | packet->routinginfo = tal_arr(packet, u8, fixed_size); |
| 530 | |
| 531 | if (sp->session_key == NULL) { |
| 532 | sp->session_key = tal(sp, struct secret); |
| 533 | randombytes_buf(sp->session_key, sizeof(struct secret)); |
| 534 | } |
| 535 | |
| 536 | params = generate_hop_params(ctx, sp->session_key->data, sp); |
| 537 | if (!params) { |
| 538 | tal_free(packet); |
| 539 | tal_free(secrets); |
| 540 | return NULL; |
| 541 | } |
| 542 | packet->version = 0; |
| 543 | memset(nexthmac.bytes, 0, sizeof(nexthmac.bytes)); |
| 544 | |
| 545 | /* BOLT #4: |
| 546 | * |
| 547 | * The packet is initialized with 1300 _random_ bytes derived from a |
| 548 | * CSPRNG |
| 549 | */ |
| 550 | /* Note that this is just hop_payloads: the rest of the packet is |
| 551 | * overwritten below or above anyway. */ |
| 552 | subkey_from_hmac("pad", sp->session_key, &padkey); |
| 553 | generate_cipher_stream(packet->routinginfo, &padkey, fixed_size); |
| 554 | |
| 555 | filler = tal_arr(tmpctx, u8, fillerSize); |
| 556 | generate_header_padding(filler, tal_bytelen(filler), fixed_size, sp, params); |
| 557 | |
| 558 | if (sp->rendezvous_id != NULL) |
| 559 | /* FIXME: Fuzz this or expose to the caller to hide encoded |
| 560 | * route length. */ |
| 561 | sphinx_prefill(packet->routinginfo, sp, max_prefill, params, |