| 1 | /** |
| 2 | * Copyright (C) 2011-2012 Juho Vähä-Herttua |
| 3 | * |
| 4 | * This library is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU Lesser General Public |
| 6 | * License as published by the Free Software Foundation; either |
| 7 | * version 2.1 of the License, or (at your option) any later version. |
| 8 | * |
| 9 | * This library is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | * Lesser General Public License for more details. |
| 13 | */ |
| 14 | |
| 15 | #include <stdlib.h> |
| 16 | #include <string.h> |
| 17 | #include <assert.h> |
| 18 | #include <math.h> |
| 19 | |
| 20 | #include "raop_buffer.h" |
| 21 | #include "raop_rtp.h" |
| 22 | #include "utils.h" |
| 23 | |
| 24 | #include <stdint.h> |
| 25 | #include "crypto/crypto.h" |
| 26 | #include "alac/alac.h" |
| 27 | |
| 28 | #define RAOP_BUFFER_LENGTH 16 |
| 29 | |
| 30 | typedef struct { |
| 31 | /* Packet available */ |
| 32 | int available; |
| 33 | |
| 34 | /* RTP header */ |
| 35 | unsigned char flags; |
| 36 | unsigned char type; |
| 37 | unsigned short seqnum; |
| 38 | unsigned int timestamp; |
| 39 | unsigned int ssrc; |
| 40 | |
| 41 | /* Audio buffer of valid length */ |
| 42 | int audio_buffer_size; |
| 43 | int audio_buffer_len; |
| 44 | void *audio_buffer; |
| 45 | } raop_buffer_entry_t; |
| 46 | |
| 47 | struct raop_buffer_s { |
| 48 | /* AES key and IV */ |
| 49 | unsigned char aeskey[RAOP_AESKEY_LEN]; |
| 50 | unsigned char aesiv[RAOP_AESIV_LEN]; |
| 51 | |
| 52 | /* ALAC decoder */ |
| 53 | ALACSpecificConfig alacConfig; |
| 54 | alac_file *alac; |
| 55 | |
| 56 | /* First and last seqnum */ |
| 57 | int is_empty; |
| 58 | unsigned short first_seqnum; |
| 59 | unsigned short last_seqnum; |
| 60 | |
| 61 | /* RTP buffer entries */ |
| 62 | raop_buffer_entry_t entries[RAOP_BUFFER_LENGTH]; |
| 63 | |
| 64 | /* Buffer of all audio buffers */ |
| 65 | int buffer_size; |
| 66 | void *buffer; |
| 67 | }; |
| 68 | |
| 69 | |
| 70 | |
| 71 | static int |
| 72 | get_fmtp_info(ALACSpecificConfig *config, const char *fmtp) |
| 73 | { |
| 74 | int intarr[12]; |
| 75 | char *original; |
| 76 | char *strptr; |
| 77 | int i; |
| 78 | |
| 79 | /* Parse fmtp string to integers */ |
| 80 | original = strptr = strdup(fmtp); |
| 81 | for (i=0; i<12; i++) { |
| 82 | if (strptr == NULL) { |
| 83 | free(original); |
| 84 | return -1; |
| 85 | } |
| 86 | intarr[i] = atoi(utils_strsep(&strptr, " ")); |
| 87 | } |
| 88 | free(original); |
| 89 | original = strptr = NULL; |
| 90 | |
| 91 | /* Fill the config struct */ |
| 92 | config->frameLength = intarr[1]; |
| 93 | config->compatibleVersion = intarr[2]; |
| 94 | config->bitDepth = intarr[3]; |
| 95 | config->pb = intarr[4]; |
| 96 | config->mb = intarr[5]; |
| 97 | config->kb = intarr[6]; |
| 98 | config->numChannels = intarr[7]; |
| 99 | config->maxRun = intarr[8]; |
| 100 | config->maxFrameBytes = intarr[9]; |
| 101 | config->avgBitRate = intarr[10]; |
| 102 | config->sampleRate = intarr[11]; |
| 103 | |
| 104 | /* Validate supported audio types */ |
| 105 | if (config->bitDepth != 16) { |
| 106 | return -2; |
| 107 | } |
| 108 | if (config->numChannels != 2) { |
| 109 | return -3; |
| 110 | } |
| 111 | |
| 112 | return 0; |
| 113 | } |
| 114 | |
| 115 | static void |
| 116 | set_decoder_info(alac_file *alac, ALACSpecificConfig *config) |
| 117 | { |
| 118 | unsigned char decoder_info[48]; |
| 119 | memset(decoder_info, 0, sizeof(decoder_info)); |
| 120 | |
| 121 | #define SET_UINT16(buf, value)do{\ |
| 122 | (buf)[0] = (unsigned char)((value) >> 8);\ |
| 123 | (buf)[1] = (unsigned char)(value);\ |
| 124 | }while(0) |
| 125 | |
| 126 | #define SET_UINT32(buf, value)do{\ |
| 127 | (buf)[0] = (unsigned char)((value) >> 24);\ |
| 128 | (buf)[1] = (unsigned char)((value) >> 16);\ |
| 129 | (buf)[2] = (unsigned char)((value) >> 8);\ |
| 130 | (buf)[3] = (unsigned char)(value);\ |
| 131 | }while(0) |
| 132 | |
| 133 | /* Construct decoder info buffer */ |
| 134 | SET_UINT32(&decoder_info[24], config->frameLength); |
| 135 | decoder_info[28] = config->compatibleVersion; |
| 136 | decoder_info[29] = config->bitDepth; |
| 137 | decoder_info[30] = config->pb; |
| 138 | decoder_info[31] = config->mb; |
| 139 | decoder_info[32] = config->kb; |
| 140 | decoder_info[33] = config->numChannels; |
| 141 | SET_UINT16(&decoder_info[34], config->maxRun); |
| 142 | SET_UINT32(&decoder_info[36], config->maxFrameBytes); |
| 143 | SET_UINT32(&decoder_info[40], config->avgBitRate); |
| 144 | SET_UINT32(&decoder_info[44], config->sampleRate); |
| 145 | alac_set_info(alac, (char *) decoder_info); |
| 146 | } |
| 147 | |
| 148 | raop_buffer_t * |
| 149 | raop_buffer_init(const char *fmtp, |
| 150 | const unsigned char *aeskey, |
| 151 | const unsigned char *aesiv) |
| 152 | { |
| 153 | raop_buffer_t *raop_buffer; |
| 154 | int audio_buffer_size; |
| 155 | ALACSpecificConfig *alacConfig; |
| 156 | int i; |
| 157 | |
| 158 | assert(fmtp); |
| 159 | assert(aeskey); |
| 160 | assert(aesiv); |
| 161 | |
| 162 | raop_buffer = calloc(1, sizeof(raop_buffer_t)); |
| 163 | if (!raop_buffer) { |
| 164 | return NULL; |
| 165 | } |
| 166 | |
| 167 | /* Parse fmtp information */ |
| 168 | alacConfig = &raop_buffer->alacConfig; |
| 169 | if (get_fmtp_info(alacConfig, fmtp) < 0) { |
| 170 | free(raop_buffer); |
| 171 | return NULL; |
| 172 | } |
| 173 | |
| 174 | /* Allocate the output audio buffers */ |
| 175 | audio_buffer_size = alacConfig->frameLength * |
| 176 | alacConfig->numChannels * |
| 177 | alacConfig->bitDepth/8; |
| 178 | raop_buffer->buffer_size = audio_buffer_size * |
| 179 | RAOP_BUFFER_LENGTH; |
| 180 | raop_buffer->buffer = malloc(raop_buffer->buffer_size); |
| 181 | if (!raop_buffer->buffer) { |
| 182 | free(raop_buffer); |
| 183 | return NULL; |
| 184 | } |
| 185 | for (i=0; i<RAOP_BUFFER_LENGTH; i++) { |
| 186 | raop_buffer_entry_t *entry = &raop_buffer->entries[i]; |
| 187 | entry->audio_buffer_size = audio_buffer_size; |
| 188 | entry->audio_buffer_len = 0; |
| 189 | entry->audio_buffer = (char *)raop_buffer->buffer+i*audio_buffer_size; |
| 190 | } |
| 191 | |
| 192 | /* Initialize ALAC decoder */ |
| 193 | raop_buffer->alac = create_alac(alacConfig->bitDepth, |
| 194 | alacConfig->numChannels); |
| 195 | if (!raop_buffer->alac) { |
| 196 | free(raop_buffer->buffer); |
| 197 | free(raop_buffer); |
| 198 | return NULL; |
| 199 | } |
| 200 | set_decoder_info(raop_buffer->alac, alacConfig); |
| 201 | |
| 202 | /* Initialize AES keys */ |
| 203 | memcpy(raop_buffer->aeskey, aeskey, RAOP_AESKEY_LEN); |
| 204 | memcpy(raop_buffer->aesiv, aesiv, RAOP_AESIV_LEN); |
| 205 | |
| 206 | /* Mark buffer as empty */ |
| 207 | raop_buffer->is_empty = 1; |
| 208 | return raop_buffer; |
| 209 | } |
| 210 | |
| 211 | void |
| 212 | raop_buffer_destroy(raop_buffer_t *raop_buffer) |
| 213 | { |
| 214 | if (raop_buffer) { |
| 215 | destroy_alac(raop_buffer->alac); |
| 216 | free(raop_buffer->buffer); |
| 217 | free(raop_buffer); |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | const ALACSpecificConfig * |
| 222 | raop_buffer_get_config(raop_buffer_t *raop_buffer) |
| 223 | { |
| 224 | assert(raop_buffer); |
| 225 | |
| 226 | return &raop_buffer->alacConfig; |
| 227 | } |
| 228 | |
| 229 | static short |
| 230 | seqnum_cmp(unsigned short s1, unsigned short s2) |
| 231 | { |
| 232 | return (s1 - s2); |
| 233 | } |
| 234 | |
| 235 | int |
| 236 | raop_buffer_queue(raop_buffer_t *raop_buffer, unsigned char *data, unsigned short datalen, int use_seqnum) |
| 237 | { |
| 238 | unsigned char packetbuf[RAOP_PACKET_LEN]; |
| 239 | unsigned short seqnum; |
| 240 | raop_buffer_entry_t *entry; |
| 241 | int encryptedlen; |
| 242 | AES_CTX aes_ctx; |
| 243 | int outputlen; |
| 244 | |
| 245 | assert(raop_buffer); |
| 246 | |
| 247 | /* Check packet data length is valid */ |
| 248 | if (datalen < 12 || datalen > RAOP_PACKET_LEN) { |
| 249 | return -1; |
| 250 | } |
| 251 | |
| 252 | /* Get correct seqnum for the packet */ |
| 253 | if (use_seqnum) { |
| 254 | seqnum = (data[2] << 8) | data[3]; |
| 255 | } else { |
| 256 | seqnum = raop_buffer->first_seqnum; |
| 257 | } |
| 258 | |
| 259 | /* If this packet is too late, just skip it */ |
| 260 | if (!raop_buffer->is_empty && seqnum_cmp(seqnum, raop_buffer->first_seqnum) < 0) { |
| 261 | return 0; |
| 262 | } |
| 263 | |
| 264 | /* Check that there is always space in the buffer, otherwise flush */ |
| 265 | if (seqnum_cmp(seqnum, raop_buffer->first_seqnum+RAOP_BUFFER_LENGTH) >= 0) { |
| 266 | raop_buffer_flush(raop_buffer, seqnum); |
| 267 | } |
| 268 | |
| 269 | /* Get entry corresponding our seqnum */ |
| 270 | entry = &raop_buffer->entries[seqnum % RAOP_BUFFER_LENGTH]; |
| 271 | if (entry->available && seqnum_cmp(entry->seqnum, seqnum) == 0) { |
| 272 | /* Packet resend, we can safely ignore */ |
| 273 | return 0; |
| 274 | } |
| 275 | |
| 276 | /* Update the raop_buffer entry header */ |
| 277 | entry->flags = data[0]; |
| 278 | entry->type = data[1]; |
| 279 | entry->seqnum = seqnum; |
| 280 | entry->timestamp = (data[4] << 24) | (data[5] << 16) | |
| 281 | (data[6] << 8) | data[7]; |
| 282 | entry->ssrc = (data[8] << 24) | (data[9] << 16) | |
| 283 | (data[10] << 8) | data[11]; |
| 284 | entry->available = 1; |
| 285 | |
| 286 | /* Decrypt audio data */ |
| 287 | encryptedlen = (datalen-12)/16*16; |
| 288 | AES_set_key(&aes_ctx, raop_buffer->aeskey, raop_buffer->aesiv, AES_MODE_128); |
| 289 | AES_convert_key(&aes_ctx); |
| 290 | AES_cbc_decrypt(&aes_ctx, &data[12], packetbuf, encryptedlen); |
| 291 | memcpy(packetbuf+encryptedlen, &data[12+encryptedlen], datalen-12-encryptedlen); |
| 292 | |
| 293 | /* Decode ALAC audio data */ |
| 294 | outputlen = entry->audio_buffer_size; |
| 295 | decode_frame(raop_buffer->alac, packetbuf, entry->audio_buffer, &outputlen); |
| 296 | entry->audio_buffer_len = outputlen; |
| 297 | |
| 298 | /* Update the raop_buffer seqnums */ |
| 299 | if (raop_buffer->is_empty) { |
| 300 | raop_buffer->first_seqnum = seqnum; |
| 301 | raop_buffer->last_seqnum = seqnum; |
| 302 | raop_buffer->is_empty = 0; |
| 303 | } |
| 304 | if (seqnum_cmp(seqnum, raop_buffer->last_seqnum) > 0) { |
| 305 | raop_buffer->last_seqnum = seqnum; |
| 306 | } |
| 307 | return 1; |
| 308 | } |
| 309 | |
| 310 | const void * |
| 311 | raop_buffer_dequeue(raop_buffer_t *raop_buffer, int *length, int no_resend) |
| 312 | { |
| 313 | short buflen; |
| 314 | raop_buffer_entry_t *entry; |
| 315 | |
| 316 | /* Calculate number of entries in the current buffer */ |
| 317 | buflen = seqnum_cmp(raop_buffer->last_seqnum, raop_buffer->first_seqnum)+1; |
| 318 | |
| 319 | /* Cannot dequeue from empty buffer */ |
| 320 | if (raop_buffer->is_empty || buflen <= 0) { |
| 321 | return NULL; |
| 322 | } |
| 323 | |
| 324 | /* Get the first buffer entry for inspection */ |
| 325 | entry = &raop_buffer->entries[raop_buffer->first_seqnum % RAOP_BUFFER_LENGTH]; |
| 326 | if (no_resend) { |
| 327 | /* If we do no resends, always return the first entry */ |
| 328 | } else if (!entry->available) { |
| 329 | /* Check how much we have space left in the buffer */ |
| 330 | if (buflen < RAOP_BUFFER_LENGTH) { |
| 331 | /* Return nothing and hope resend gets on time */ |
| 332 | return NULL; |
| 333 | } |
| 334 | /* Risk of buffer overrun, return empty buffer */ |
| 335 | } |
| 336 | |
| 337 | /* Update buffer and validate entry */ |
| 338 | raop_buffer->first_seqnum += 1; |
| 339 | if (!entry->available) { |
| 340 | /* Return an empty audio buffer to skip audio */ |
| 341 | *length = entry->audio_buffer_size; |
| 342 | memset(entry->audio_buffer, 0, *length); |
| 343 | return entry->audio_buffer; |
| 344 | } |
| 345 | entry->available = 0; |
| 346 | |
| 347 | /* Return entry audio buffer */ |
| 348 | *length = entry->audio_buffer_len; |
| 349 | entry->audio_buffer_len = 0; |
| 350 | return entry->audio_buffer; |
| 351 | } |
| 352 | |
| 353 | void |
| 354 | raop_buffer_handle_resends(raop_buffer_t *raop_buffer, raop_resend_cb_t resend_cb, void *opaque) |
| 355 | { |
| 356 | raop_buffer_entry_t *entry; |
| 357 | |
| 358 | assert(raop_buffer); |
| 359 | assert(resend_cb); |
| 360 | |
| 361 | if (seqnum_cmp(raop_buffer->first_seqnum, raop_buffer->last_seqnum) < 0) { |
| 362 | int seqnum, count; |
| 363 | |
| 364 | for (seqnum=raop_buffer->first_seqnum; seqnum_cmp(seqnum, raop_buffer->last_seqnum)<0; seqnum++) { |
| 365 | entry = &raop_buffer->entries[seqnum % RAOP_BUFFER_LENGTH]; |
| 366 | if (entry->available) { |
| 367 | break; |
| 368 | } |
| 369 | } |
| 370 | if (seqnum_cmp(seqnum, raop_buffer->first_seqnum) == 0) { |
| 371 | return; |
| 372 | } |
| 373 | count = seqnum_cmp(seqnum, raop_buffer->first_seqnum); |
| 374 | resend_cb(opaque, raop_buffer->first_seqnum, count); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | void |
| 379 | raop_buffer_flush(raop_buffer_t *raop_buffer, int next_seq) |
| 380 | { |
| 381 | int i; |
| 382 | |
| 383 | assert(raop_buffer); |
| 384 | |
| 385 | for (i=0; i<RAOP_BUFFER_LENGTH; i++) { |
| 386 | raop_buffer->entries[i].available = 0; |
| 387 | raop_buffer->entries[i].audio_buffer_len = 0; |
| 388 | } |
| 389 | if (next_seq < 0 || next_seq > 0xffff) { |
| 390 | raop_buffer->is_empty = 1; |
| 391 | } else { |
| 392 | raop_buffer->first_seqnum = next_seq; |
| 393 | raop_buffer->last_seqnum = next_seq-1; |
| 394 | } |
| 395 | } |