avcodec/avcodec.h: Add encryption info side data.

This new side-data will contain info on how a packet is encrypted.
This allows the app to handle packet decryption.

Signed-off-by: Jacob Trimble <modmaker@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

4 files changed, 498 insertions, 1 deletions

diff --git a/libavutil/Makefile b/libavutil/Makefile
index 17ec1f1aa9..a63ba523c9 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -24,6 +24,7 @@ HEADERS = adler32.h                                                     \
           dict.h                                                        \
           display.h                                                     \
           downmix_info.h                                                \
+          encryption_info.h                                             \
           error.h                                                       \
           eval.h                                                        \
           fifo.h                                                        \
@@ -107,6 +108,7 @@ OBJS = adler32.o                                                        \
        dict.o                                                           \
        display.o                                                        \
        downmix_info.o                                                   \
+       encryption_info.o                                                \
        error.o                                                          \
        eval.o                                                           \
        fifo.o                                                           \
diff --git a/libavutil/encryption_info.c b/libavutil/encryption_info.c
new file mode 100644
index 0000000000..20a752d6b4
--- /dev/null
+++ b/libavutil/encryption_info.c
@@ -0,0 +1,295 @@
+/**
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "encryption_info.h"
+#include "mem.h"
+#include "intreadwrite.h"
+
+#define FF_ENCRYPTION_INFO_EXTRA 24
+
+// The format of the AVEncryptionInfo side data:
+// u32be scheme
+// u32be crypt_byte_block
+// u32be skip_byte_block
+// u32be key_id_size
+// u32be iv_size
+// u32be subsample_count
+// u8[key_id_size] key_id
+// u8[iv_size] iv
+// {
+//   u32be bytes_of_clear_data
+//   u32be bytes_of_protected_data
+// }[subsample_count]
+
+AVEncryptionInfo *av_encryption_info_alloc(uint32_t subsample_count, uint32_t key_id_size, uint32_t iv_size)
+{
+    AVEncryptionInfo *info;
+
+    info = av_mallocz(sizeof(*info));
+    if (!info)
+        return NULL;
+
+    info->key_id = av_mallocz(key_id_size);
+    info->key_id_size = key_id_size;
+    info->iv = av_mallocz(iv_size);
+    info->iv_size = iv_size;
+    info->subsamples = av_mallocz_array(subsample_count, sizeof(*info->subsamples));
+    info->subsample_count = subsample_count;
+
+    // Allow info->subsamples to be NULL if there are no subsamples.
+    if (!info->key_id || !info->iv || (!info->subsamples && subsample_count)) {
+        av_encryption_info_free(info);
+        return NULL;
+    }
+
+    return info;
+}
+
+AVEncryptionInfo *av_encryption_info_clone(const AVEncryptionInfo *info)
+{
+    AVEncryptionInfo *ret;
+
+    ret = av_encryption_info_alloc(info->subsample_count, info->key_id_size, info->iv_size);
+    if (!ret)
+        return NULL;
+
+    ret->scheme = info->scheme;
+    ret->crypt_byte_block = info->crypt_byte_block;
+    ret->skip_byte_block = info->skip_byte_block;
+    memcpy(ret->iv, info->iv, info->iv_size);
+    memcpy(ret->key_id, info->key_id, info->key_id_size);
+    memcpy(ret->subsamples, info->subsamples, sizeof(*info->subsamples) * info->subsample_count);
+    return ret;
+}
+
+void av_encryption_info_free(AVEncryptionInfo *info)
+{
+    if (info) {
+        av_free(info->key_id);
+        av_free(info->iv);
+        av_free(info->subsamples);
+        av_free(info);
+    }
+}
+
+AVEncryptionInfo *av_encryption_info_get_side_data(const uint8_t* buffer, size_t size)
+{
+    AVEncryptionInfo *info;
+    uint64_t key_id_size, iv_size, subsample_count, i;
+
+    if (!buffer || size < FF_ENCRYPTION_INFO_EXTRA)
+        return NULL;
+
+    key_id_size = AV_RB32(buffer + 12);
+    iv_size = AV_RB32(buffer + 16);
+    subsample_count = AV_RB32(buffer + 20);
+
+    if (size < FF_ENCRYPTION_INFO_EXTRA + key_id_size + iv_size + subsample_count * 8)
+        return NULL;
+
+    info = av_encryption_info_alloc(subsample_count, key_id_size, iv_size);
+    if (!info)
+        return NULL;
+
+    info->scheme = AV_RB32(buffer);
+    info->crypt_byte_block = AV_RB32(buffer + 4);
+    info->skip_byte_block = AV_RB32(buffer + 8);
+    memcpy(info->key_id, buffer + 24, key_id_size);
+    memcpy(info->iv, buffer + key_id_size + 24, iv_size);
+
+    buffer += key_id_size + iv_size + 24;
+    for (i = 0; i < subsample_count; i++) {
+        info->subsamples[i].bytes_of_clear_data = AV_RB32(buffer);
+        info->subsamples[i].bytes_of_protected_data = AV_RB32(buffer + 4);
+        buffer += 8;
+    }
+
+    return info;
+}
+
+uint8_t *av_encryption_info_add_side_data(const AVEncryptionInfo *info, size_t *size)
+{
+    uint8_t *buffer, *cur_buffer;
+    uint32_t i;
+
+    if (UINT32_MAX - FF_ENCRYPTION_INFO_EXTRA < info->key_id_size ||
+        UINT32_MAX - FF_ENCRYPTION_INFO_EXTRA - info->key_id_size < info->iv_size ||
+        (UINT32_MAX - FF_ENCRYPTION_INFO_EXTRA - info->key_id_size - info->iv_size) / 8 < info->subsample_count) {
+        return NULL;
+    }
+
+    *size = FF_ENCRYPTION_INFO_EXTRA + info->key_id_size + info->iv_size +
+            (info->subsample_count * 8);
+    cur_buffer = buffer = av_malloc(*size);
+    if (!buffer)
+        return NULL;
+
+    AV_WB32(cur_buffer,      info->scheme);
+    AV_WB32(cur_buffer +  4, info->crypt_byte_block);
+    AV_WB32(cur_buffer +  8, info->skip_byte_block);
+    AV_WB32(cur_buffer + 12, info->key_id_size);
+    AV_WB32(cur_buffer + 16, info->iv_size);
+    AV_WB32(cur_buffer + 20, info->subsample_count);
+    cur_buffer += 24;
+    memcpy(cur_buffer, info->key_id, info->key_id_size);
+    cur_buffer += info->key_id_size;
+    memcpy(cur_buffer, info->iv, info->iv_size);
+    cur_buffer += info->iv_size;
+    for (i = 0; i < info->subsample_count; i++) {
+        AV_WB32(cur_buffer, info->subsamples[i].bytes_of_clear_data);
+        AV_WB32(cur_buffer + 4, info->subsamples[i].bytes_of_protected_data);
+        cur_buffer += 8;
+    }
+
+    return buffer;
+}
+
+// The format of the AVEncryptionInitInfo side data:
+// u32be system_id_size
+// u32be num_key_ids
+// u32be key_id_size
+// u32be data_size
+// u8[system_id_size] system_id
+// u8[key_id_size][num_key_id] key_ids
+// u8[data_size] data
+
+#define FF_ENCRYPTION_INIT_INFO_EXTRA 16
+
+AVEncryptionInitInfo *av_encryption_init_info_alloc(
+    uint32_t system_id_size, uint32_t num_key_ids, uint32_t key_id_size, uint32_t data_size)
+{
+    AVEncryptionInitInfo *info;
+    uint32_t i;
+
+    info = av_mallocz(sizeof(*info));
+    if (!info)
+        return NULL;
+
+    info->system_id = av_mallocz(system_id_size);
+    info->system_id_size = system_id_size;
+    info->key_ids = key_id_size ? av_mallocz_array(num_key_ids, sizeof(*info->key_ids)) : NULL;
+    info->num_key_ids = num_key_ids;
+    info->key_id_size = key_id_size;
+    info->data = av_mallocz(data_size);
+    info->data_size = data_size;
+
+    // Allow pointers to be NULL if the size is 0.
+    if ((!info->system_id && system_id_size) || (!info->data && data_size) ||
+        (!info->key_ids && num_key_ids && key_id_size)) {
+        av_encryption_init_info_free(info);
+        return NULL;
+    }
+
+    if (key_id_size) {
+        for (i = 0; i < num_key_ids; i++) {
+            info->key_ids[i] = av_mallocz(key_id_size);
+            if (!info->key_ids[i]) {
+                av_encryption_init_info_free(info);
+                return NULL;
+            }
+        }
+    }
+
+    return info;
+}
+
+void av_encryption_init_info_free(AVEncryptionInitInfo *info)
+{
+    uint32_t i;
+    if (info) {
+        for (i = 0; i < info->num_key_ids; i++) {
+            av_free(info->key_ids[i]);
+        }
+        av_free(info->system_id);
+        av_free(info->key_ids);
+        av_free(info->data);
+        av_free(info);
+    }
+}
+
+AVEncryptionInitInfo *av_encryption_init_info_get_side_data(
+    const uint8_t *side_data, size_t side_data_size)
+{
+    AVEncryptionInitInfo *info;
+    uint64_t system_id_size, num_key_ids, key_id_size, data_size, i;
+
+    if (!side_data || side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA)
+        return NULL;
+
+    system_id_size = AV_RB32(side_data);
+    num_key_ids = AV_RB32(side_data + 4);
+    key_id_size = AV_RB32(side_data + 8);
+    data_size = AV_RB32(side_data + 12);
+
+    // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
+    if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size)
+        return NULL;
+
+    info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
+    if (!info)
+        return NULL;
+
+    memcpy(info->system_id, side_data + 16, system_id_size);
+    side_data += system_id_size + 16;
+    for (i = 0; i < num_key_ids; i++) {
+      memcpy(info->key_ids[i], side_data, key_id_size);
+      side_data += key_id_size;
+    }
+    memcpy(info->data, side_data, data_size);
+
+    return info;
+}
+
+uint8_t *av_encryption_init_info_add_side_data(const AVEncryptionInitInfo *info, size_t *side_data_size)
+{
+    uint8_t *buffer, *cur_buffer;
+    uint32_t i, max_size;
+
+    if (UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA < info->system_id_size ||
+        UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size < info->data_size) {
+        return NULL;
+    }
+
+    if (info->num_key_ids) {
+        max_size = UINT32_MAX - FF_ENCRYPTION_INIT_INFO_EXTRA - info->system_id_size - info->data_size;
+        if (max_size / info->num_key_ids < info->key_id_size)
+            return NULL;
+    }
+
+    *side_data_size = FF_ENCRYPTION_INIT_INFO_EXTRA + info->system_id_size +
+                      info->data_size + (info->num_key_ids * info->key_id_size);
+    cur_buffer = buffer = av_malloc(*side_data_size);
+    if (!buffer)
+        return NULL;
+
+    AV_WB32(cur_buffer,      info->system_id_size);
+    AV_WB32(cur_buffer +  4, info->num_key_ids);
+    AV_WB32(cur_buffer +  8, info->key_id_size);
+    AV_WB32(cur_buffer + 12, info->data_size);
+    cur_buffer += 16;
+
+    memcpy(cur_buffer, info->system_id, info->system_id_size);
+    cur_buffer += info->system_id_size;
+    for (i = 0; i < info->num_key_ids; i++) {
+        memcpy(cur_buffer, info->key_ids[i], info->key_id_size);
+        cur_buffer += info->key_id_size;
+    }
+    memcpy(cur_buffer, info->data, info->data_size);
+
+    return buffer;
+}
diff --git a/libavutil/encryption_info.h b/libavutil/encryption_info.h
new file mode 100644
index 0000000000..47dc3a35ca
--- /dev/null
+++ b/libavutil/encryption_info.h
@@ -0,0 +1,200 @@
+/**
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_ENCRYPTION_INFO_H
+#define AVUTIL_ENCRYPTION_INFO_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+typedef struct AVSubsampleEncryptionInfo {
+    /** The number of bytes that are clear. */
+    unsigned int bytes_of_clear_data;
+
+    /**
+     * The number of bytes that are protected.  If using pattern encryption,
+     * the pattern applies to only the protected bytes; if not using pattern
+     * encryption, all these bytes are encrypted.
+     */
+    unsigned int bytes_of_protected_data;
+} AVSubsampleEncryptionInfo;
+
+/**
+ * This describes encryption info for a packet.  This contains frame-specific
+ * info for how to decrypt the packet before passing it to the decoder.
+ *
+ * The size of this struct is not part of the public ABI.
+ */
+typedef struct AVEncryptionInfo {
+    /** The fourcc encryption scheme. */
+    uint32_t scheme;
+
+    /**
+     * Only used for pattern encryption.  This is the number of 16-byte blocks
+     * that are encrypted.
+     */
+    uint32_t crypt_byte_block;
+
+    /**
+     * Only used for pattern encryption.  This is the number of 16-byte blocks
+     * that are clear.
+     */
+    uint32_t skip_byte_block;
+
+    /**
+     * The ID of the key used to encrypt the packet.  This should always be
+     * 16 bytes long, but may be changed in the future.
+     */
+    uint8_t *key_id;
+    uint32_t key_id_size;
+
+    /**
+     * The initialization vector.  This may have been zero-filled to be the
+     * correct block size.  This should always be 16 bytes long, but may be
+     * changed in the future.
+     */
+    uint8_t *iv;
+    uint32_t iv_size;
+
+    /**
+     * An array of subsample encryption info specifying how parts of the sample
+     * are encrypted.  If there are no subsamples, then the whole sample is
+     * encrypted.
+     */
+    AVSubsampleEncryptionInfo *subsamples;
+    uint32_t subsample_count;
+} AVEncryptionInfo;
+
+/**
+ * This describes info used to initialize an encryption key system.
+ *
+ * The size of this struct is not part of the public ABI.
+ */
+typedef struct AVEncryptionInitInfo {
+    /**
+     * A unique identifier for the key system this is for, can be NULL if it
+     * is not known.  This should always be 16 bytes, but may change in the
+     * future.
+     */
+    uint8_t* system_id;
+    uint32_t system_id_size;
+
+    /**
+     * An array of key IDs this initialization data is for.  All IDs are the
+     * same length.  Can be NULL if there are no known key IDs.
+     */
+    uint8_t** key_ids;
+    /** The number of key IDs. */
+    uint32_t num_key_ids;
+    /**
+     * The number of bytes in each key ID.  This should always be 16, but may
+     * change in the future.
+     */
+    uint32_t key_id_size;
+
+    /**
+     * Key-system specific initialization data.  This data is copied directly
+     * from the file and the format depends on the specific key system.  This
+     * can be NULL if there is no initialization data; in that case, there
+     * will be at least one key ID.
+     */
+    uint8_t* data;
+    uint32_t data_size;
+} AVEncryptionInitInfo;
+
+/**
+ * Allocates an AVEncryptionInfo structure and sub-pointers to hold the given
+ * number of subsamples.  This will allocate pointers for the key ID, IV,
+ * and subsample entries, set the size members, and zero-initialize the rest.
+ *
+ * @param subsample_count The number of subsamples.
+ * @param key_id_size The number of bytes in the key ID, should be 16.
+ * @param key_id_size The number of bytes in the IV, should be 16.
+ *
+ * @return The new AVEncryptionInfo structure, or NULL on error.
+ */
+AVEncryptionInfo *av_encryption_info_alloc(uint32_t subsample_count, uint32_t key_id_size, uint32_t iv_size);
+
+/**
+ * Allocates an AVEncryptionInfo structure with a copy of the given data.
+ * @return The new AVEncryptionInfo structure, or NULL on error.
+ */
+AVEncryptionInfo *av_encryption_info_clone(const AVEncryptionInfo *info);
+
+/**
+ * Frees the given encryption info object.  This MUST NOT be used to free the
+ * side-data data pointer, that should use normal side-data methods.
+ */
+void av_encryption_info_free(AVEncryptionInfo *info);
+
+/**
+ * Creates a copy of the AVEncryptionInfo that is contained in the given side
+ * data.  The resulting object should be passed to av_encryption_info_free()
+ * when done.
+ *
+ * @return The new AVEncryptionInfo structure, or NULL on error.
+ */
+AVEncryptionInfo *av_encryption_info_get_side_data(const uint8_t *side_data, size_t side_data_size);
+
+/**
+ * Allocates and initializes side data that holds a copy of the given encryption
+ * info.  The resulting pointer should be either freed using av_free or given
+ * to av_packet_add_side_data().
+ *
+ * @return The new side-data pointer, or NULL.
+ */
+uint8_t *av_encryption_info_add_side_data(
+      const AVEncryptionInfo *info, size_t *side_data_size);
+
+
+/**
+ * Allocates an AVEncryptionInitInfo structure and sub-pointers to hold the
+ * given sizes.  This will allocate pointers and set all the fields.
+ *
+ * @return The new AVEncryptionInitInfo structure, or NULL on error.
+ */
+AVEncryptionInitInfo *av_encryption_init_info_alloc(
+    uint32_t system_id_size, uint32_t num_key_ids, uint32_t key_id_size, uint32_t data_size);
+
+/**
+ * Frees the given encryption init info object.  This MUST NOT be used to free
+ * the side-data data pointer, that should use normal side-data methods.
+ */
+void av_encryption_init_info_free(AVEncryptionInitInfo* info);
+
+/**
+ * Creates a copy of the AVEncryptionInitInfo that is contained in the given
+ * side data.  The resulting object should be passed to
+ * av_encryption_init_info_free() when done.
+ *
+ * @return The new AVEncryptionInitInfo structure, or NULL on error.
+ */
+AVEncryptionInitInfo *av_encryption_init_info_get_side_data(
+    const uint8_t* side_data, size_t side_data_size);
+
+/**
+ * Allocates and initializes side data that holds a copy of the given encryption
+ * init info.  The resulting pointer should be either freed using av_free or
+ * given to av_packet_add_side_data().
+ *
+ * @return The new side-data pointer, or NULL.
+ */
+uint8_t *av_encryption_init_info_add_side_data(
+    const AVEncryptionInitInfo *info, size_t *side_data_size);
+
+#endif /* AVUTIL_ENCRYPTION_INFO_H */
diff --git a/libavutil/version.h b/libavutil/version.h
index d166bb30e7..d3dd2df544 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  56
-#define LIBAVUTIL_VERSION_MINOR  11
+#define LIBAVUTIL_VERSION_MINOR  12
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \