1 /* b64dec.c - Simple Base64 decoder.
2 * Copyright (C) 2008, 2011 Free Software Foundation, Inc.
3 * Copyright (C) 2008, 2011, 2016 g10 Code GmbH
5 * This file is part of GnuPG.
7 * This file is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as
9 * published by the Free Software Foundation; either version 2.1 of
10 * the License, or (at your option) any later version.
12 * This file is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public License
18 * along with this program; if not, see <https://www.gnu.org/licenses/>.
32 /* The reverse base-64 list used for base-64 decoding. */
33 static unsigned char const asctobin[128] =
35 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
36 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
37 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
38 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
39 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
40 0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
41 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
42 0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
43 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
44 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
45 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
46 0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
47 0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
48 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
49 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
50 0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff
55 s_init, s_idle, s_lfseen, s_beginseen, s_waitheader, s_waitblank, s_begin,
56 s_b64_0, s_b64_1, s_b64_2, s_b64_3,
57 s_waitendtitle, s_waitend
62 /* Initialize the context for the base64 decoder. If TITLE is NULL a
63 plain base64 decoding is done. If it is the empty string the
64 decoder will skip everything until a "-----BEGIN " line has been
65 seen, decoding ends at a "----END " line. */
67 b64dec_start (struct b64state *state, const char *title)
69 memset (state, 0, sizeof *state);
72 state->title = xtrystrdup (title);
74 state->lasterr = gpg_error_from_syserror ();
80 return state->lasterr;
84 /* Do in-place decoding of base-64 data of LENGTH in BUFFER. Stores the
85 new length of the buffer at R_NBYTES. */
87 b64dec_proc (struct b64state *state, void *buffer, size_t length,
90 enum decoder_states ds = state->idx;
91 unsigned char val = state->radbuf[0];
92 int pos = state->quad_count;
96 return state->lasterr;
101 state->lasterr = gpg_error (GPG_ERR_EOF);
102 xfree (state->title);
104 return state->lasterr;
107 for (s=d=buffer; length && !state->stop_seen; length--, s++)
122 if (*s != "-----BEGIN "[pos])
136 if (*s != "PGP "[pos])
137 ds = s_begin; /* Not a PGP armor. */
149 ds = s_b64_0; /* blank line found. */
150 else if (*s == ' ' || *s == '\r' || *s == '\t')
151 ; /* Ignore spaces. */
154 /* Armor header line. Note that we don't care that our
155 * FSM accepts a header prefixed with spaces. */
156 ds = s_waitheader; /* Wait for next header. */
170 if (*s == '-' && state->title)
172 /* Not a valid Base64 character: assume end
178 /* Pad character: stop */
181 ds = state->title? s_waitendtitle : s_waitend;
183 else if (*s == '\n' || *s == ' ' || *s == '\r' || *s == '\t')
184 ; /* Skip white spaces. */
185 else if ( (*s & 0x80)
186 || (c = asctobin[*(unsigned char *)s]) == 255)
188 /* Skip invalid encodings. */
189 state->invalid_encoding = 1;
191 else if (ds == s_b64_0)
196 else if (ds == s_b64_1)
203 else if (ds == s_b64_2)
224 state->stop_seen = 1;
233 state->radbuf[0] = val;
234 state->quad_count = pos;
235 *r_nbytes = (d -(char*) buffer);
240 /* This function needs to be called before releasing the decoder
241 state. It may return an error code in case an encoding error has
242 been found during decoding. */
244 b64dec_finish (struct b64state *state)
246 xfree (state->title);
250 return state->lasterr;
252 return state->invalid_encoding? gpg_error(GPG_ERR_BAD_DATA): 0;