keyanalyze/pgpring/pgppacket.c

   1 /*
   2  * Copyright (C) 2001 Thomas Roessler <roessler@does-not-exist.org>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of
   7  * the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public
  15  * License along with this program; if not, write to the Free
  16  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  17  * MA 02111, USA.
  18  */
  19
  20 #include "config.h"
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <time.h>
  26
  27 #include "sha1.h"
  28 #include "lib.h"
  29 #include "pgplib.h"
  30 #include "pgppacket.h"
  31
  32 #define CHUNKSIZE 1024
  33
  34 static unsigned char *pbuf = NULL;
  35 static size_t plen = 0;
  36
  37 static int read_material (size_t material, size_t * used, FILE * fp)
  38 {
  39   if (*used + material >= plen)
  40   {
  41     unsigned char *p;
  42     size_t nplen;
  43
  44     nplen = *used + material + CHUNKSIZE;
  45
  46     if (!(p = realloc (pbuf, nplen)))   /* __MEM_CHECKED__ */
  47     {
  48       perror ("realloc");
  49       return -1;
  50     }
  51     plen = nplen;
  52     pbuf = p;
  53   }
  54
  55   if (fread (pbuf + *used, 1, material, fp) < material)
  56   {
  57     perror ("fread");
  58     return -1;
  59   }
  60
  61   *used += material;
  62   return 0;
  63 }
  64
  65 unsigned char *pgp_read_packet (FILE * fp, size_t * len)
  66 {
  67   size_t used = 0;
  68   long startpos;
  69   unsigned char ctb;
  70   unsigned char b;
  71   size_t material;
  72
  73   startpos = ftell (fp);
  74
  75   if (!plen)
  76   {
  77     plen = CHUNKSIZE;
  78     pbuf = safe_malloc (plen);
  79   }
  80
  81   if (fread (&ctb, 1, 1, fp) < 1)
  82   {
  83     if (!feof (fp))
  84       perror ("fread");
  85     goto bail;
  86   }
  87
  88   if (!(ctb & 0x80))
  89   {
  90     goto bail;
  91   }
  92
  93   if (ctb & 0x40)               /* handle PGP 5.0 packets. */
  94   {
  95     int partial = 0;
  96     pbuf[0] = ctb;
  97     used++;
  98
  99     do
 100     {
 101       if (fread (&b, 1, 1, fp) < 1)
 102       {
 103         perror ("fread");
 104         goto bail;
 105       }
 106
 107       if (b < 192)
 108       {
 109         material = b;
 110         partial = 0;
 111         /* material -= 1; */
 112       }
 113       else if (192 <= b && b <= 223)
 114       {
 115         material = (b - 192) * 256;
 116         if (fread (&b, 1, 1, fp) < 1)
 117         {
 118           perror ("fread");
 119           goto bail;
 120         }
 121         material += b + 192;
 122         partial = 0;
 123         /* material -= 2; */
 124       }
 125       else if (b < 255)
 126       {
 127         material = 1 << (b & 0x1f);
 128         partial = 1;
 129         /* material -= 1; */
 130       }
 131       else
 132         /* b == 255 */
 133       {
 134         unsigned char buf[4];
 135         if (fread (buf, 4, 1, fp) < 1)
 136         {
 137           perror ("fread");
 138           goto bail;
 139         }
 140         /*assert( sizeof(material) >= 4 ); */
 141         material = buf[0] << 24;
 142         material |= buf[1] << 16;
 143         material |= buf[2] << 8;
 144         material |= buf[3];
 145         partial = 0;
 146         /* material -= 5; */
 147       }
 148
 149       if (read_material (material, &used, fp) == -1)
 150         goto bail;
 151
 152     }
 153     while (partial);
 154   }
 155   else
 156     /* Old-Style PGP */
 157   {
 158     int bytes = 0;
 159     pbuf[0] = 0x80 | ((ctb >> 2) & 0x0f);
 160     used++;
 161
 162     switch (ctb & 0x03)
 163     {
 164       case 0:
 165       {
 166         if (fread (&b, 1, 1, fp) < 1)
 167         {
 168           perror ("fread");
 169           goto bail;
 170         }
 171
 172         material = b;
 173         break;
 174       }
 175
 176       case 1:
 177       bytes = 2;
 178
 179       case 2:
 180       {
 181         int i;
 182
 183         if (!bytes)
 184           bytes = 4;
 185
 186         material = 0;
 187
 188         for (i = 0; i < bytes; i++)
 189         {
 190           if (fread (&b, 1, 1, fp) < 1)
 191           {
 192             perror ("fread");
 193             goto bail;
 194           }
 195
 196           material = (material << 8) + b;
 197         }
 198         break;
 199       }
 200
 201       default:
 202       goto bail;
 203     }
 204
 205     if (read_material (material, &used, fp) == -1)
 206       goto bail;
 207   }
 208
 209   if (len)
 210     *len = used;
 211
 212   return pbuf;
 213
 214 bail:
 215
 216   fseek (fp, startpos, SEEK_SET);
 217   return NULL;
 218 }
 219
 220 void pgp_release_packet (void)
 221 {
 222   plen = 0;
 223   safe_free (&pbuf);
 224 }
 225