g10/textfilter.c

   1 /* textfilter.c
   2  * Copyright (C) 1998, 1999, 2000, 2001, 2004 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <assert.h>
  26
  27 #include "gpg.h"
  28 #include "status.h"
  29 #include "iobuf.h"
  30 #include "util.h"
  31 #include "filter.h"
  32 #include "i18n.h"
  33 #include "options.h"
  34 #include "status.h"
  35
  36 #ifdef HAVE_DOSISH_SYSTEM
  37 #define LF "\r\n"
  38 #else
  39 #define LF "\n"
  40 #endif
  41
  42 #define MAX_LINELEN 19995 /* a little bit smaller than in armor.c */
  43                           /* to make sure that a warning is displayed while */
  44                           /* creating a message */
  45
  46 static unsigned
  47 len_without_trailing_chars( byte *line, unsigned len, const char *trimchars )
  48 {
  49     byte *p, *mark;
  50     unsigned n;
  51
  52     for(mark=NULL, p=line, n=0; n < len; n++, p++ ) {
  53         if( strchr( trimchars, *p ) ) {
  54             if( !mark )
  55                 mark = p;
  56         }
  57         else
  58             mark = NULL;
  59     }
  60
  61     return mark? (mark - line) : len;
  62 }
  63
  64
  65 static int
  66 standard( text_filter_context_t *tfx, IOBUF a,
  67           byte *buf, size_t size, size_t *ret_len)
  68 {
  69     int rc=0;
  70     size_t len = 0;
  71     unsigned maxlen;
  72
  73     assert( size > 10 );
  74     size -= 2;  /* reserve 2 bytes to append CR,LF */
  75     while( !rc && len < size ) {
  76         int lf_seen;
  77
  78         while( len < size && tfx->buffer_pos < tfx->buffer_len )
  79             buf[len++] = tfx->buffer[tfx->buffer_pos++];
  80         if( len >= size )
  81             continue;
  82
  83         /* read the next line */
  84         maxlen = MAX_LINELEN;
  85         tfx->buffer_pos = 0;
  86         tfx->buffer_len = iobuf_read_line( a, &tfx->buffer,
  87                                            &tfx->buffer_size, &maxlen );
  88         if( !maxlen )
  89             tfx->truncated++;
  90         if( !tfx->buffer_len ) {
  91             if( !len )
  92                 rc = -1; /* eof */
  93             break;
  94         }
  95         lf_seen = tfx->buffer[tfx->buffer_len-1] == '\n';
  96
  97         /* The story behind this is that 2440 says that textmode
  98            hashes should canonicalize line endings to CRLF and remove
  99            spaces and tabs.  2440bis-12 says to just canonicalize to
 100            CRLF.  1.4.0 was released using the bis-12 behavior, but it
 101            was discovered that many mail clients do not canonicalize
 102            PGP/MIME signature text appropriately (and were relying on
 103            GnuPG to handle trailing spaces).  So, we default to the
 104            2440 behavior, but use the 2440bis-12 behavior if the user
 105            specifies --no-rfc2440-text.  The default will be changed
 106            at some point in the future when the mail clients have been
 107            upgraded.  Aside from PGP/MIME and broken mail clients,
 108            this makes no difference to any signatures in the real
 109            world except for a textmode detached signature.  PGP always
 110            used the 2440bis-12 behavior (ignoring 2440 itself), so
 111            this actually makes us compatible with PGP textmode
 112            detached signatures for the first time. */
 113         if(opt.rfc2440_text)
 114           tfx->buffer_len=trim_trailing_chars(tfx->buffer,tfx->buffer_len,
 115                                               " \t\r\n");
 116         else
 117           tfx->buffer_len=trim_trailing_chars(tfx->buffer,tfx->buffer_len,
 118                                               "\r\n");
 119
 120         if( lf_seen ) {
 121             tfx->buffer[tfx->buffer_len++] = '\r';
 122             tfx->buffer[tfx->buffer_len++] = '\n';
 123         }
 124     }
 125     *ret_len = len;
 126     return rc;
 127 }
 128
 129
 130 /****************
 131  * The filter is used to make canonical text: Lines are terminated by
 132  * CR, LF, trailing white spaces are removed.
 133  */
 134 int
 135 text_filter( void *opaque, int control,
 136              IOBUF a, byte *buf, size_t *ret_len)
 137 {
 138     size_t size = *ret_len;
 139     text_filter_context_t *tfx = opaque;
 140     int rc=0;
 141
 142     if( control == IOBUFCTRL_UNDERFLOW ) {
 143         rc = standard( tfx, a, buf, size, ret_len );
 144     }
 145     else if( control == IOBUFCTRL_FREE ) {
 146         if( tfx->truncated )
 147             log_error(_("can't handle text lines longer than %d characters\n"),
 148                         MAX_LINELEN );
 149         xfree( tfx->buffer );
 150         tfx->buffer = NULL;
 151     }
 152     else if( control == IOBUFCTRL_DESC )
 153         *(char**)buf = "text_filter";
 154     return rc;
 155 }
 156
 157
 158 /****************
 159  * Copy data from INP to OUT and do some escaping if requested.
 160  * md is updated as required by rfc2440
 161  */
 162 int
 163 copy_clearsig_text( IOBUF out, IOBUF inp, gcry_md_hd_t md,
 164                     int escape_dash, int escape_from, int pgp2mode )
 165 {
 166     unsigned int maxlen;
 167     byte *buffer = NULL;    /* malloced buffer */
 168     unsigned int bufsize;   /* and size of this buffer */
 169     unsigned int n;
 170     int truncated = 0;
 171     int pending_lf = 0;
 172
 173     if( !opt.pgp2_workarounds )
 174         pgp2mode = 0;
 175
 176     if( !escape_dash )
 177         escape_from = 0;
 178
 179     write_status_begin_signing (md);
 180
 181     for(;;) {
 182         maxlen = MAX_LINELEN;
 183         n = iobuf_read_line( inp, &buffer, &bufsize, &maxlen );
 184         if( !maxlen )
 185             truncated++;
 186
 187         if( !n )
 188             break; /* read_line has returned eof */
 189
 190         /* update the message digest */
 191         if( escape_dash ) {
 192             if( pending_lf ) {
 193                 gcry_md_putc ( md, '\r' );
 194                 gcry_md_putc ( md, '\n' );
 195             }
 196             gcry_md_write ( md, buffer,
 197                             len_without_trailing_chars (buffer, n,
 198                                                         pgp2mode?
 199                                                         " \r\n":" \t\r\n"));
 200         }
 201         else
 202             gcry_md_write ( md, buffer, n );
 203         pending_lf = buffer[n-1] == '\n';
 204
 205         /* write the output */
 206         if(    ( escape_dash && *buffer == '-')
 207             || ( escape_from && n > 4 && !memcmp(buffer, "From ", 5 ) ) ) {
 208             iobuf_put( out, '-' );
 209             iobuf_put( out, ' ' );
 210         }
 211
 212 #if  0 /*defined(HAVE_DOSISH_SYSTEM)*/
 213         /* We don't use this anymore because my interpretation of rfc2440 7.1
 214          * is that there is no conversion needed.  If one decides to
 215          * clearsign a unix file on a DOS box he will get a mixed line endings.
 216          * If at some point it turns out, that a conversion is a nice feature
 217          * we can make an option out of it.
 218          */
 219         /* make sure the lines do end in CR,LF */
 220         if( n > 1 && ( (buffer[n-2] == '\r' && buffer[n-1] == '\n' )
 221                             || (buffer[n-2] == '\n' && buffer[n-1] == '\r'))) {
 222             iobuf_write( out, buffer, n-2 );
 223             iobuf_put( out, '\r');
 224             iobuf_put( out, '\n');
 225         }
 226         else if( n && buffer[n-1] == '\n' ) {
 227             iobuf_write( out, buffer, n-1 );
 228             iobuf_put( out, '\r');
 229             iobuf_put( out, '\n');
 230         }
 231         else
 232             iobuf_write( out, buffer, n );
 233
 234 #else
 235         iobuf_write( out, buffer, n );
 236 #endif
 237     }
 238
 239     /* at eof */
 240     if( !pending_lf ) { /* make sure that the file ends with a LF */
 241         iobuf_writestr( out, LF );
 242         if( !escape_dash )
 243             gcry_md_putc( md, '\n' );
 244     }
 245
 246     if( truncated )
 247         log_info(_("input line longer than %d characters\n"), MAX_LINELEN );
 248
 249     return 0; /* okay */
 250 }