diff options
Diffstat (limited to 'src/lib/istream-base64-decoder.c')
| -rw-r--r-- | src/lib/istream-base64-decoder.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/src/lib/istream-base64-decoder.c b/src/lib/istream-base64-decoder.c new file mode 100644 index 0000000..6eaa842 --- /dev/null +++ b/src/lib/istream-base64-decoder.c @@ -0,0 +1,171 @@ +/* Copyright (c) 2013-2018 Dovecot authors, see the included COPYING file */ + +#include "lib.h" +#include "buffer.h" +#include "base64.h" +#include "hex-binary.h" +#include "istream-private.h" +#include "istream-base64.h" + +struct base64_decoder_istream { + struct istream_private istream; + + struct base64_decoder decoder; +}; + +static int i_stream_read_parent(struct istream_private *stream) +{ + size_t size; + ssize_t ret; + + size = i_stream_get_data_size(stream->parent); + if (size >= 4) + return 1; + + /* we have less than one base64 block. + see if there is more data available. */ + ret = i_stream_read_memarea(stream->parent); + if (ret <= 0) { + stream->istream.stream_errno = stream->parent->stream_errno; + return ret; + } + size = i_stream_get_data_size(stream->parent); + i_assert(size != 0); + return 1; +} + +static int +i_stream_base64_try_decode_block(struct base64_decoder_istream *bstream) +{ + struct istream_private *stream = &bstream->istream; + const unsigned char *data; + size_t size, avail, pos; + buffer_t buf; + + data = i_stream_get_data(stream->parent, &size); + if (size == 0) + return 0; + + if (!i_stream_try_alloc(stream, (size+3)/4*3, &avail)) + return -2; + + buffer_create_from_data(&buf, stream->w_buffer + stream->pos, avail); + if (base64_decode_more(&bstream->decoder, data, size, &pos, &buf) < 0) { + io_stream_set_error(&stream->iostream, + "Invalid base64 data: 0x%s", + binary_to_hex(data+pos, I_MIN(size-pos, 8))); + stream->istream.stream_errno = EINVAL; + return -1; + } + + stream->pos += buf.used; + i_stream_skip(stream->parent, pos); + return pos > 0 ? 1 : 0; +} + +static void +i_stream_base64_finish_decode(struct base64_decoder_istream *bstream) +{ + struct istream_private *stream = &bstream->istream; + + i_assert(i_stream_get_data_size(stream->parent) == 0); + + if (base64_decode_finish(&bstream->decoder) < 0) { + io_stream_set_error(&stream->iostream, + "Base64 data ends prematurely"); + stream->istream.stream_errno = EPIPE; + } +} + +static ssize_t i_stream_base64_decoder_read(struct istream_private *stream) +{ + struct base64_decoder_istream *bstream = + container_of(stream, struct base64_decoder_istream, istream); + size_t pre_count, post_count; + int ret; + + if (base64_decode_is_finished(&bstream->decoder)) { + stream->istream.eof = TRUE; + return -1; + } + + do { + ret = i_stream_read_parent(stream); + if (ret == 0) + return 0; + if (ret < 0 && ret != -2) { + if (stream->istream.stream_errno != 0) + return -1; + if (i_stream_get_data_size(stream->parent) == 0) { + i_stream_base64_finish_decode(bstream); + stream->istream.eof = TRUE; + return -1; + } + } + + /* encode as many blocks as fits into destination buffer */ + pre_count = stream->pos - stream->skip; + while ((ret = i_stream_base64_try_decode_block(bstream)) > 0) ; + post_count = stream->pos - stream->skip; + } while (ret == 0 && pre_count == post_count); + + if (ret < 0 && pre_count == post_count) + return ret; + + i_assert(post_count > pre_count); + return post_count - pre_count; +} + +static void +i_stream_base64_decoder_seek(struct istream_private *stream, + uoff_t v_offset, bool mark) +{ + struct base64_decoder_istream *bstream = + container_of(stream, struct base64_decoder_istream, istream); + + if (v_offset < stream->istream.v_offset) { + /* seeking backwards - go back to beginning and seek + forward from there. */ + stream->parent_expected_offset = stream->parent_start_offset; + stream->skip = stream->pos = 0; + stream->istream.v_offset = 0; + i_stream_seek(stream->parent, 0); + + base64_decode_reset(&bstream->decoder); + } + i_stream_default_seek_nonseekable(stream, v_offset, mark); +} + +static struct istream * +i_stream_create_base64_decoder_common(const struct base64_scheme *b64, + struct istream *input) +{ + struct base64_decoder_istream *bstream; + + bstream = i_new(struct base64_decoder_istream, 1); + bstream->istream.max_buffer_size = input->real_stream->max_buffer_size; + + bstream->istream.read = i_stream_base64_decoder_read; + bstream->istream.seek = i_stream_base64_decoder_seek; + + bstream->istream.istream.readable_fd = FALSE; + bstream->istream.istream.blocking = input->blocking; + bstream->istream.istream.seekable = input->seekable; + + base64_decode_init(&bstream->decoder, b64, 0); + + return i_stream_create(&bstream->istream, input, + i_stream_get_fd(input), 0); +} + +struct istream * +i_stream_create_base64_decoder(struct istream *input) +{ + return i_stream_create_base64_decoder_common(&base64_scheme, input); +} + +struct istream * +i_stream_create_base64url_decoder(struct istream *input) +{ + return i_stream_create_base64_decoder_common(&base64url_scheme, input); +} |