diff options
| -rw-r--r-- | libavformat/crypto.c | 116 |
1 files changed, 114 insertions, 2 deletions
diff --git a/libavformat/crypto.c b/libavformat/crypto.c index 31a438c94c..346c7061b4 100644 --- a/libavformat/crypto.c +++ b/libavformat/crypto.c @@ -37,6 +37,8 @@ typedef struct CryptoContext { outbuffer[BLOCKSIZE*MAX_BUFFER_BLOCKS]; uint8_t *outptr; int indata, indata_used, outdata; + int64_t position; // position in file - used in seek + int flags; int eof; uint8_t *key; int keylen; @@ -110,6 +112,7 @@ static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary const char *nested_url; int ret = 0; CryptoContext *c = h->priv_data; + c->flags = flags; if (!av_strstart(uri, "crypto+", &nested_url) && !av_strstart(uri, "crypto:", &nested_url)) { @@ -118,6 +121,8 @@ static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary goto err; } + c->position = 0; + if (flags & AVIO_FLAG_READ) { if ((ret = set_aes_arg(c, &c->decrypt_key, &c->decrypt_keylen, c->key, c->keylen, "decryption key")) < 0) @@ -153,6 +158,10 @@ static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary ret = av_aes_init(c->aes_decrypt, c->decrypt_key, BLOCKSIZE*8, 1); if (ret < 0) goto err; + + // pass back information about the context we openned + if (c->hd->is_streamed) + h->is_streamed = c->hd->is_streamed; } if (flags & AVIO_FLAG_WRITE) { @@ -164,12 +173,13 @@ static int crypto_open2(URLContext *h, const char *uri, int flags, AVDictionary ret = av_aes_init(c->aes_encrypt, c->encrypt_key, BLOCKSIZE*8, 0); if (ret < 0) goto err; + // for write, we must be streamed + // - linear write only for crytpo aes-128-cbc + h->is_streamed = 1; } c->pad_len = 0; - h->is_streamed = 1; - err: return ret; } @@ -184,6 +194,7 @@ retry: memcpy(buf, c->outptr, size); c->outptr += size; c->outdata -= size; + c->position = c->position + size; return size; } // We avoid using the last block until we've found EOF, @@ -223,6 +234,106 @@ retry: goto retry; } +static int64_t crypto_seek(URLContext *h, int64_t pos, int whence) +{ + CryptoContext *c = h->priv_data; + int64_t block; + int64_t newpos; + + if (c->flags & AVIO_FLAG_WRITE) { + av_log(h, AV_LOG_ERROR, + "Crypto: seek not supported for write\r\n"); + /* seems the most appropriate error to return */ + return AVERROR(ESPIPE); + } + + // reset eof, else we won't read it correctly if we already hit eof. + c->eof = 0; + + switch (whence) { + case SEEK_SET: + break; + case SEEK_CUR: + pos = pos + c->position; + break; + case SEEK_END: { + int64_t newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE ); + if (newpos < 0) { + av_log(h, AV_LOG_ERROR, + "Crypto: seek_end - can't get file size (pos=%lld)\r\n", (long long int)pos); + return newpos; + } + pos = newpos - pos; + } + break; + case AVSEEK_SIZE: { + int64_t newpos = ffurl_seek( c->hd, pos, AVSEEK_SIZE ); + return newpos; + } + break; + default: + av_log(h, AV_LOG_ERROR, + "Crypto: no support for seek where 'whence' is %d\r\n", whence); + return AVERROR(EINVAL); + } + + c->outdata = 0; + c->indata = 0; + c->indata_used = 0; + c->outptr = c->outbuffer; + + // identify the block containing the IV for the + // next block we will decrypt + block = pos/BLOCKSIZE; + if (block == 0) { + // restore the iv to the seed one - this is the iv for the FIRST block + memcpy( c->decrypt_iv, c->iv, c->ivlen ); + c->position = 0; + } else { + // else, go back one block - we will get av_cyrpt to read this block + // which it will then store use as the iv. + // note that the DECRYPTED result will not be correct, + // but will be discarded + block--; + c->position = (block * BLOCKSIZE); + } + + newpos = ffurl_seek( c->hd, c->position, SEEK_SET ); + if (newpos < 0) { + av_log(h, AV_LOG_ERROR, + "Crypto: nested protocol no support for seek or seek failed\n"); + return newpos; + } + + // read and discard from here up to required position + // (which will set the iv correctly to it). + if (pos - c->position) { + uint8_t buff[BLOCKSIZE*2]; // maximum size of pos-c->position + int len = pos - c->position; + int res; + + while (len > 0) { + // note: this may not return all the bytes first time + res = crypto_read(h, buff, len); + if (res < 0) + break; + len -= res; + } + + // if we did not get all the bytes + if (len != 0) { + char errbuf[100] = "unknown error"; + av_strerror(res, errbuf, sizeof(errbuf)); + av_log(h, AV_LOG_ERROR, + "Crypto: discard read did not get all the bytes (%d remain) - read returned (%d)-%s\n", + len, res, errbuf); + return AVERROR(EINVAL); + } + } + + return c->position; +} + static int crypto_write(URLContext *h, const unsigned char *buf, int size) { CryptoContext *c = h->priv_data; @@ -288,6 +399,7 @@ static int crypto_close(URLContext *h) const URLProtocol ff_crypto_protocol = { .name = "crypto", .url_open2 = crypto_open2, + .url_seek = crypto_seek, .url_read = crypto_read, .url_write = crypto_write, .url_close = crypto_close, |