LCOV - code coverage report
Current view: top level - common - b64dec.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 0 98 0.0 %
Date: 2016-11-29 15:00:56 Functions: 0 3 0.0 %

          Line data    Source code
       1             : /* b64dec.c - Simple Base64 decoder.
       2             :  * Copyright (C) 2008, 2011 Free Software Foundation, Inc.
       3             :  * Copyright (C) 2008, 2011, 2016 g10 Code GmbH
       4             :  *
       5             :  * This file is part of GnuPG.
       6             :  *
       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.
      11             :  *
      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.
      16             :  *
      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/>.
      19             :  */
      20             : 
      21             : #include <config.h>
      22             : #include <stdio.h>
      23             : #include <stdlib.h>
      24             : #include <string.h>
      25             : #include <errno.h>
      26             : #include <assert.h>
      27             : 
      28             : #include "i18n.h"
      29             : #include "util.h"
      30             : 
      31             : 
      32             : /* The reverse base-64 list used for base-64 decoding. */
      33             : static unsigned char const asctobin[128] =
      34             :   {
      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
      51             :   };
      52             : 
      53             : enum decoder_states
      54             :   {
      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
      58             :   };
      59             : 
      60             : 
      61             : 
      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.  */
      66             : gpg_error_t
      67           0 : b64dec_start (struct b64state *state, const char *title)
      68             : {
      69           0 :   memset (state, 0, sizeof *state);
      70           0 :   if (title)
      71             :     {
      72           0 :       state->title = xtrystrdup (title);
      73           0 :       if (!state->title)
      74           0 :         state->lasterr = gpg_error_from_syserror ();
      75             :       else
      76           0 :         state->idx = s_init;
      77             :     }
      78             :   else
      79           0 :     state->idx = s_b64_0;
      80           0 :   return state->lasterr;
      81             : }
      82             : 
      83             : 
      84             : /* Do in-place decoding of base-64 data of LENGTH in BUFFER.  Stores the
      85             :    new length of the buffer at R_NBYTES. */
      86             : gpg_error_t
      87           0 : b64dec_proc (struct b64state *state, void *buffer, size_t length,
      88             :              size_t *r_nbytes)
      89             : {
      90           0 :   enum decoder_states ds = state->idx;
      91           0 :   unsigned char val = state->radbuf[0];
      92           0 :   int pos = state->quad_count;
      93             :   char *d, *s;
      94             : 
      95           0 :   if (state->lasterr)
      96           0 :     return state->lasterr;
      97             : 
      98           0 :   if (state->stop_seen)
      99             :     {
     100           0 :       *r_nbytes = 0;
     101           0 :       state->lasterr = gpg_error (GPG_ERR_EOF);
     102           0 :       xfree (state->title);
     103           0 :       state->title = NULL;
     104           0 :       return state->lasterr;
     105             :     }
     106             : 
     107           0 :   for (s=d=buffer; length && !state->stop_seen; length--, s++)
     108             :     {
     109             :     again:
     110           0 :       switch (ds)
     111             :         {
     112             :         case s_idle:
     113           0 :           if (*s == '\n')
     114             :             {
     115           0 :               ds = s_lfseen;
     116           0 :               pos = 0;
     117             :             }
     118           0 :           break;
     119             :         case s_init:
     120           0 :           ds = s_lfseen;
     121             :         case s_lfseen:
     122           0 :           if (*s != "-----BEGIN "[pos])
     123             :             {
     124           0 :               ds = s_idle;
     125           0 :               goto again;
     126             :             }
     127           0 :           else if (pos == 10)
     128             :             {
     129           0 :               pos = 0;
     130           0 :               ds = s_beginseen;
     131             :             }
     132             :           else
     133           0 :             pos++;
     134           0 :           break;
     135             :         case s_beginseen:
     136           0 :           if (*s != "PGP "[pos])
     137           0 :             ds = s_begin; /* Not a PGP armor.  */
     138           0 :           else if (pos == 3)
     139           0 :             ds = s_waitheader;
     140             :           else
     141           0 :             pos++;
     142           0 :           break;
     143             :         case s_waitheader:
     144           0 :           if (*s == '\n')
     145           0 :             ds = s_waitblank;
     146           0 :           break;
     147             :         case s_waitblank:
     148           0 :           if (*s == '\n')
     149           0 :             ds = s_b64_0; /* blank line found.  */
     150           0 :           else if (*s == ' ' || *s == '\r' || *s == '\t')
     151             :             ; /* Ignore spaces. */
     152             :           else
     153             :             {
     154             :               /* Armor header line.  Note that we don't care that our
     155             :                * FSM accepts a header prefixed with spaces.  */
     156           0 :               ds = s_waitheader; /* Wait for next header.  */
     157             :             }
     158           0 :           break;
     159             :         case s_begin:
     160           0 :           if (*s == '\n')
     161           0 :             ds = s_b64_0;
     162           0 :           break;
     163             :         case s_b64_0:
     164             :         case s_b64_1:
     165             :         case s_b64_2:
     166             :         case s_b64_3:
     167             :           {
     168             :             int c;
     169             : 
     170           0 :             if (*s == '-' && state->title)
     171             :               {
     172             :                 /* Not a valid Base64 character: assume end
     173             :                    header.  */
     174           0 :                 ds = s_waitend;
     175             :               }
     176           0 :             else if (*s == '=')
     177             :               {
     178             :                 /* Pad character: stop */
     179           0 :                 if (ds == s_b64_1)
     180           0 :                   *d++ = val;
     181           0 :                 ds = state->title? s_waitendtitle : s_waitend;
     182             :               }
     183           0 :             else if (*s == '\n' || *s == ' ' || *s == '\r' || *s == '\t')
     184             :               ; /* Skip white spaces. */
     185           0 :             else if ( (*s & 0x80)
     186           0 :                       || (c = asctobin[*(unsigned char *)s]) == 255)
     187             :               {
     188             :                 /* Skip invalid encodings.  */
     189           0 :                 state->invalid_encoding = 1;
     190             :               }
     191           0 :             else if (ds == s_b64_0)
     192             :               {
     193           0 :                 val = c << 2;
     194           0 :                 ds = s_b64_1;
     195             :               }
     196           0 :             else if (ds == s_b64_1)
     197             :               {
     198           0 :                 val |= (c>>4)&3;
     199           0 :                 *d++ = val;
     200           0 :                 val = (c<<4)&0xf0;
     201           0 :                 ds = s_b64_2;
     202             :               }
     203           0 :             else if (ds == s_b64_2)
     204             :               {
     205           0 :                 val |= (c>>2)&15;
     206           0 :                 *d++ = val;
     207           0 :                 val = (c<<6)&0xc0;
     208           0 :                 ds = s_b64_3;
     209             :               }
     210             :             else
     211             :               {
     212           0 :                 val |= c&0x3f;
     213           0 :                 *d++ = val;
     214           0 :                 ds = s_b64_0;
     215             :               }
     216             :           }
     217           0 :           break;
     218             :         case s_waitendtitle:
     219           0 :           if (*s == '-')
     220           0 :             ds = s_waitend;
     221           0 :           break;
     222             :         case s_waitend:
     223           0 :           if ( *s == '\n')
     224           0 :             state->stop_seen = 1;
     225           0 :           break;
     226             :         default:
     227           0 :           BUG();
     228             :         }
     229             :     }
     230             : 
     231             : 
     232           0 :   state->idx = ds;
     233           0 :   state->radbuf[0] = val;
     234           0 :   state->quad_count = pos;
     235           0 :   *r_nbytes = (d -(char*) buffer);
     236           0 :   return 0;
     237             : }
     238             : 
     239             : 
     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. */
     243             : gpg_error_t
     244           0 : b64dec_finish (struct b64state *state)
     245             : {
     246           0 :   xfree (state->title);
     247           0 :   state->title = NULL;
     248             : 
     249           0 :   if (state->lasterr)
     250           0 :     return state->lasterr;
     251             : 
     252           0 :   return state->invalid_encoding? gpg_error(GPG_ERR_BAD_DATA): 0;
     253             : }

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