From 35c0dd2755dbcea2539117cf33959a1a9e497f12 Mon Sep 17 00:00:00 2001 From: Philip Withnall Date: Fri, 17 Mar 2017 11:30:47 +0000 Subject: [PATCH] gbase64: Fix base-64 stepped encoding with small chunks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If encoding with small chunks such that the call to g_base64_encode_close() has to deal with 0 < x < 24 bits of remaining state, the encoding code would not correctly use zeroes to pad out the state — it would use left-over state from an earlier iteration in the encoding process. This resulted in invalid base-64 encodings. Add a unit test for incremental encoding using different sized chunks too. Thanks to Rainier Perske for reporting and analysing the bug. https://bugzilla.gnome.org/show_bug.cgi?id=780066 Signed-off-by: Philip Withnall --- glib/gbase64.c | 1 + glib/tests/base64.c | 58 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) diff --git a/glib/gbase64.c b/glib/gbase64.c index 7bca5ab62..4dc151873 100644 --- a/glib/gbase64.c +++ b/glib/gbase64.c @@ -222,6 +222,7 @@ g_base64_encode_close (gboolean break_lines, goto skip; case 1: outptr[2] = '='; + c2 = 0; /* saved state here is not relevant */ skip: outptr [0] = base64_alphabet [ c1 >> 2 ]; outptr [1] = base64_alphabet [ c2 >> 4 | ( (c1&0x3) << 4 )]; diff --git a/glib/tests/base64.c b/glib/tests/base64.c index ffb00d532..86875a29b 100644 --- a/glib/tests/base64.c +++ b/glib/tests/base64.c @@ -236,6 +236,58 @@ test_base64_encode (void) } } +/* Test that incremental and all-in-one encoding of strings of a length which + * is not a multiple of 3 bytes behave the same, as the state carried over + * between g_base64_encode_step() calls varies depending on how the input is + * split up. This is like the test_base64_decode_smallblock() test, but for + * encoding. */ +static void +test_base64_encode_incremental_small_block (gconstpointer block_size_p) +{ + gsize i; + struct MyRawData myraw; + + g_test_bug ("780066"); + + generate_databuffer_for_base64 (&myraw); + + for (i = 0; ok_100_encode_strs[i] != NULL; i++) + { + const guint block_size = GPOINTER_TO_UINT (block_size_p); + gchar *encoded_complete = NULL; + gchar encoded_stepped[1024]; + gint state = 0, save = 0; + gsize len_written, len_read, len_to_read, input_length; + + input_length = i + 1; + + /* Do it all at once. */ + encoded_complete = g_base64_encode (myraw.data, input_length); + + /* Split the data up so some number of bits remain after each step. */ + for (len_written = 0, len_read = 0; len_read < input_length; len_read += len_to_read) + { + len_to_read = MIN (block_size, input_length - len_read); + len_written += g_base64_encode_step (myraw.data + len_read, len_to_read, + FALSE, + encoded_stepped + len_written, + &state, &save); + } + + len_written += g_base64_encode_close (FALSE, encoded_stepped + len_written, + &state, &save); + g_assert_cmpuint (len_written, <, G_N_ELEMENTS (encoded_stepped)); + + /* Nul-terminate to make string comparison easier. */ + encoded_stepped[len_written] = '\0'; + + /* Compare results. They should be the same. */ + g_assert_cmpstr (encoded_complete, ==, ok_100_encode_strs[i]); + g_assert_cmpstr (encoded_stepped, ==, encoded_complete); + + g_free (encoded_complete); + } +} static void decode_and_compare (const gchar *datap, @@ -361,6 +413,7 @@ main (int argc, char *argv[]) gint i; g_test_init (&argc, &argv, NULL); + g_test_bug_base ("https://bugzilla.gnome.org/browse.cgi?product="); for (i = 0; i < DATA_SIZE; i++) data[i] = (guchar)i; @@ -370,6 +423,11 @@ main (int argc, char *argv[]) g_test_add_data_func ("/base64/full/3", GINT_TO_POINTER (2), test_full); g_test_add_data_func ("/base64/full/4", GINT_TO_POINTER (3), test_full); + g_test_add_data_func ("/base64/encode/incremental/small-block/1", GINT_TO_POINTER (1), test_base64_encode_incremental_small_block); + g_test_add_data_func ("/base64/encode/incremental/small-block/2", GINT_TO_POINTER (2), test_base64_encode_incremental_small_block); + g_test_add_data_func ("/base64/encode/incremental/small-block/3", GINT_TO_POINTER (3), test_base64_encode_incremental_small_block); + g_test_add_data_func ("/base64/encode/incremental/small-block/4", GINT_TO_POINTER (4), test_base64_encode_incremental_small_block); + g_test_add_data_func ("/base64/incremental/nobreak/1", GINT_TO_POINTER (DATA_SIZE), test_incremental_nobreak); g_test_add_data_func ("/base64/incremental/break/1", GINT_TO_POINTER (DATA_SIZE), test_incremental_break);