--- /dev/null
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <math.h>
+
+#include "raop_buffer.h"
+#include "raop_rtp.h"
+#include "utils.h"
+
+#include <stdint.h>
+#include "crypto/crypto.h"
+#include "alac/alac.h"
+
+#define RAOP_BUFFER_LENGTH 16
+
+typedef struct {
+ /* Packet available */
+ int available;
+
+ /* RTP header */
+ unsigned char flags;
+ unsigned char type;
+ unsigned short seqnum;
+ unsigned int timestamp;
+ unsigned int ssrc;
+
+ /* Audio buffer of valid length */
+ int audio_buffer_size;
+ int audio_buffer_len;
+ void *audio_buffer;
+} raop_buffer_entry_t;
+
+struct raop_buffer_s {
+ /* AES key and IV */
+ unsigned char aeskey[RAOP_AESKEY_LEN];
+ unsigned char aesiv[RAOP_AESIV_LEN];
+
+ /* ALAC decoder */
+ ALACSpecificConfig alacConfig;
+ alac_file *alac;
+
+ /* First and last seqnum */
+ int is_empty;
+ unsigned short first_seqnum;
+ unsigned short last_seqnum;
+
+ /* RTP buffer entries */
+ raop_buffer_entry_t entries[RAOP_BUFFER_LENGTH];
+
+ /* Buffer of all audio buffers */
+ int buffer_size;
+ void *buffer;
+};
+
+
+
+static int
+get_fmtp_info(ALACSpecificConfig *config, const char *fmtp)
+{
+ int intarr[12];
+ char *strptr;
+ int i;
+
+ /* Parse fmtp string to integers */
+ strptr = strdup(fmtp);
+ for (i=0; i<12; i++) {
+ if (strptr == NULL) {
+ free(strptr);
+ return -1;
+ }
+ intarr[i] = atoi(utils_strsep(&strptr, " "));
+ }
+ free(strptr);
+ strptr = NULL;
+
+ /* Fill the config struct */
+ config->frameLength = intarr[1];
+ config->compatibleVersion = intarr[2];
+ config->bitDepth = intarr[3];
+ config->pb = intarr[4];
+ config->mb = intarr[5];
+ config->kb = intarr[6];
+ config->numChannels = intarr[7];
+ config->maxRun = intarr[8];
+ config->maxFrameBytes = intarr[9];
+ config->avgBitRate = intarr[10];
+ config->sampleRate = intarr[11];
+
+ /* Validate supported audio types */
+ if (config->bitDepth != 16) {
+ return -2;
+ }
+ if (config->numChannels != 2) {
+ return -3;
+ }
+
+ return 0;
+}
+
+static void
+set_decoder_info(alac_file *alac, ALACSpecificConfig *config)
+{
+ unsigned char decoder_info[48];
+ memset(decoder_info, 0, sizeof(decoder_info));
+
+#define SET_UINT16(buf, value)do{\
+ (buf)[0] = (unsigned char)((value) >> 8);\
+ (buf)[1] = (unsigned char)(value);\
+ }while(0)
+
+#define SET_UINT32(buf, value)do{\
+ (buf)[0] = (unsigned char)((value) >> 24);\
+ (buf)[1] = (unsigned char)((value) >> 16);\
+ (buf)[2] = (unsigned char)((value) >> 8);\
+ (buf)[3] = (unsigned char)(value);\
+ }while(0)
+
+ /* Construct decoder info buffer */
+ SET_UINT32(&decoder_info[24], config->frameLength);
+ decoder_info[28] = config->compatibleVersion;
+ decoder_info[29] = config->bitDepth;
+ decoder_info[30] = config->pb;
+ decoder_info[31] = config->mb;
+ decoder_info[32] = config->kb;
+ decoder_info[33] = config->numChannels;
+ SET_UINT16(&decoder_info[34], config->maxRun);
+ SET_UINT32(&decoder_info[36], config->maxFrameBytes);
+ SET_UINT32(&decoder_info[40], config->avgBitRate);
+ SET_UINT32(&decoder_info[44], config->sampleRate);
+ alac_set_info(alac, (char *) decoder_info);
+}
+
+raop_buffer_t *
+raop_buffer_init(const char *fmtp,
+ const unsigned char *aeskey,
+ const unsigned char *aesiv)
+{
+ raop_buffer_t *raop_buffer;
+ int audio_buffer_size;
+ ALACSpecificConfig *alacConfig;
+ int i;
+
+ assert(fmtp);
+ assert(aeskey);
+ assert(aesiv);
+
+ raop_buffer = calloc(1, sizeof(raop_buffer_t));
+ if (!raop_buffer) {
+ return NULL;
+ }
+
+ /* Parse fmtp information */
+ alacConfig = &raop_buffer->alacConfig;
+ if (get_fmtp_info(alacConfig, fmtp) < 0) {
+ free(raop_buffer);
+ return NULL;
+ }
+
+ /* Allocate the output audio buffers */
+ audio_buffer_size = alacConfig->frameLength *
+ alacConfig->numChannels *
+ alacConfig->bitDepth/8;
+ raop_buffer->buffer_size = audio_buffer_size *
+ RAOP_BUFFER_LENGTH;
+ raop_buffer->buffer = malloc(raop_buffer->buffer_size);
+ if (!raop_buffer->buffer) {
+ free(raop_buffer);
+ return NULL;
+ }
+ for (i=0; i<RAOP_BUFFER_LENGTH; i++) {
+ raop_buffer_entry_t *entry = &raop_buffer->entries[i];
+ entry->audio_buffer_size = audio_buffer_size;
+ entry->audio_buffer_len = 0;
+ entry->audio_buffer = raop_buffer->buffer+i*audio_buffer_size;
+ }
+
+ /* Initialize ALAC decoder */
+ raop_buffer->alac = create_alac(alacConfig->bitDepth,
+ alacConfig->numChannels);
+ if (!raop_buffer->alac) {
+ free(raop_buffer->buffer);
+ free(raop_buffer);
+ return NULL;
+ }
+ set_decoder_info(raop_buffer->alac, alacConfig);
+
+ /* Initialize AES keys */
+ memcpy(raop_buffer->aeskey, aeskey, RAOP_AESKEY_LEN);
+ memcpy(raop_buffer->aesiv, aesiv, RAOP_AESIV_LEN);
+
+ /* Mark buffer as empty */
+ raop_buffer->is_empty = 1;
+ return raop_buffer;
+}
+
+void
+raop_buffer_destroy(raop_buffer_t *raop_buffer)
+{
+ if (raop_buffer) {
+ free(raop_buffer->buffer);
+ free(raop_buffer->alac);
+ free(raop_buffer);
+ }
+}
+
+const ALACSpecificConfig *
+raop_buffer_get_config(raop_buffer_t *raop_buffer)
+{
+ assert(raop_buffer);
+
+ return &raop_buffer->alacConfig;
+}
+
+static short
+seqnum_cmp(unsigned short s1, unsigned short s2)
+{
+ return (s1 - s2);
+}
+
+int
+raop_buffer_queue(raop_buffer_t *raop_buffer, unsigned char *data, unsigned short datalen, int use_seqnum)
+{
+ unsigned char packetbuf[RAOP_PACKET_LEN];
+ unsigned short seqnum;
+ raop_buffer_entry_t *entry;
+ int encryptedlen;
+ AES_CTX aes_ctx;
+ int outputlen;
+
+ assert(raop_buffer);
+
+ /* Check packet data length is valid */
+ if (datalen < 12 || datalen > RAOP_PACKET_LEN) {
+ return -1;
+ }
+
+ /* Get correct seqnum for the packet */
+ if (use_seqnum) {
+ seqnum = (data[2] << 8) | data[3];
+ } else {
+ seqnum = raop_buffer->first_seqnum;
+ }
+
+ /* If this packet is too late, just skip it */
+ if (!raop_buffer->is_empty && seqnum_cmp(seqnum, raop_buffer->first_seqnum) < 0) {
+ return 0;
+ }
+
+ /* Check that there is always space in the buffer, otherwise flush */
+ if (seqnum_cmp(seqnum, raop_buffer->first_seqnum+RAOP_BUFFER_LENGTH) >= 0) {
+ raop_buffer_flush(raop_buffer, seqnum);
+ }
+
+ /* Get entry corresponding our seqnum */
+ entry = &raop_buffer->entries[seqnum % RAOP_BUFFER_LENGTH];
+ if (entry->available && seqnum_cmp(entry->seqnum, seqnum) == 0) {
+ /* Packet resend, we can safely ignore */
+ return 0;
+ }
+
+ /* Update the raop_buffer entry header */
+ entry->flags = data[0];
+ entry->type = data[1];
+ entry->seqnum = seqnum;
+ entry->timestamp = (data[4] << 24) | (data[5] << 16) |
+ (data[6] << 8) | data[7];
+ entry->ssrc = (data[8] << 24) | (data[9] << 16) |
+ (data[10] << 8) | data[11];
+ entry->available = 1;
+
+ /* Decrypt audio data */
+ encryptedlen = (datalen-12)/16*16;
+ AES_set_key(&aes_ctx, raop_buffer->aeskey, raop_buffer->aesiv, AES_MODE_128);
+ AES_convert_key(&aes_ctx);
+ AES_cbc_decrypt(&aes_ctx, &data[12], packetbuf, encryptedlen);
+ memcpy(packetbuf+encryptedlen, &data[12+encryptedlen], datalen-12-encryptedlen);
+
+ /* Decode ALAC audio data */
+ outputlen = entry->audio_buffer_size;
+ decode_frame(raop_buffer->alac, packetbuf, entry->audio_buffer, &outputlen);
+ entry->audio_buffer_len = outputlen;
+
+ /* Update the raop_buffer seqnums */
+ if (raop_buffer->is_empty) {
+ raop_buffer->first_seqnum = seqnum;
+ raop_buffer->last_seqnum = seqnum;
+ raop_buffer->is_empty = 0;
+ }
+ if (seqnum_cmp(seqnum, raop_buffer->last_seqnum) > 0) {
+ raop_buffer->last_seqnum = seqnum;
+ }
+ return 1;
+}
+
+const void *
+raop_buffer_dequeue(raop_buffer_t *raop_buffer, int *length, int no_resend)
+{
+ short buflen;
+ raop_buffer_entry_t *entry;
+
+ /* Calculate number of entries in the current buffer */
+ buflen = seqnum_cmp(raop_buffer->last_seqnum, raop_buffer->first_seqnum)+1;
+
+ /* Cannot dequeue from empty buffer */
+ if (raop_buffer->is_empty || buflen <= 0) {
+ return NULL;
+ }
+
+ /* Get the first buffer entry for inspection */
+ entry = &raop_buffer->entries[raop_buffer->first_seqnum % RAOP_BUFFER_LENGTH];
+ if (no_resend) {
+ /* If we do no resends, always return the first entry */
+ } else if (!entry->available) {
+ /* Check how much we have space left in the buffer */
+ if (buflen < RAOP_BUFFER_LENGTH) {
+ /* Return nothing and hope resend gets on time */
+ return NULL;
+ }
+ /* Risk of buffer overrun, return empty buffer */
+ }
+
+ /* Update buffer and validate entry */
+ raop_buffer->first_seqnum += 1;
+ if (!entry->available) {
+ /* Return an empty audio buffer to skip audio */
+ *length = entry->audio_buffer_size;
+ memset(entry->audio_buffer, 0, *length);
+ return entry->audio_buffer;
+ }
+ entry->available = 0;
+
+ /* Return entry audio buffer */
+ *length = entry->audio_buffer_len;
+ entry->audio_buffer_len = 0;
+ return entry->audio_buffer;
+}
+
+void
+raop_buffer_handle_resends(raop_buffer_t *raop_buffer, raop_resend_cb_t resend_cb, void *opaque)
+{
+ raop_buffer_entry_t *entry;
+
+ assert(raop_buffer);
+ assert(resend_cb);
+
+ if (seqnum_cmp(raop_buffer->first_seqnum, raop_buffer->last_seqnum) < 0) {
+ int seqnum, count;
+
+ for (seqnum=raop_buffer->first_seqnum; seqnum_cmp(seqnum, raop_buffer->last_seqnum)<0; seqnum++) {
+ entry = &raop_buffer->entries[seqnum % RAOP_BUFFER_LENGTH];
+ if (entry->available) {
+ break;
+ }
+ }
+ if (seqnum_cmp(seqnum, raop_buffer->first_seqnum) == 0) {
+ return;
+ }
+ count = seqnum_cmp(seqnum, raop_buffer->first_seqnum);
+ resend_cb(opaque, raop_buffer->first_seqnum, count);
+ }
+}
+
+void
+raop_buffer_flush(raop_buffer_t *raop_buffer, int next_seq)
+{
+ int i;
+
+ assert(raop_buffer);
+
+ for (i=0; i<RAOP_BUFFER_LENGTH; i++) {
+ raop_buffer->entries[i].available = 0;
+ raop_buffer->entries[i].audio_buffer_len = 0;
+ }
+ if (next_seq < 0 || next_seq > 0xffff) {
+ raop_buffer->is_empty = 1;
+ } else {
+ raop_buffer->first_seqnum = next_seq;
+ raop_buffer->last_seqnum = next_seq-1;
+ }
+}
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