trunk/Gnupg/armor.c

/* armor.c - Armor filter
 * Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <windows.h>
#include <sys/types.h>

#include "openpgp.h"
#include "packet.h"

#define LF "\r\n"

#define MAX_LINELEN 20000

#define CRCINIT 0xB704CE
#define CRCPOLY 0X864CFB
#define CRCUPDATE(a,c) do {                                                 \
                        a = ((a) << 8) ^ crc_table[((a)&0xff >> 16) ^ (c)]; \
                        a &= 0x00ffffff;                                    \
                    } while(0)
static u32 crc_table[256];
static byte bintoasc[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                         "abcdefghijklmnopqrstuvwxyz"
                         "0123456789+/";
static byte asctobin[256]; /* runtime initialized */
static int is_initialized;
static int armor_errno = 0;
static char armor_error[256];

typedef enum {
    fhdrHASArmor = 0,
    fhdrNOArmor,
    fhdrINIT,
    fhdrINITCont,
    fhdrINITSkip,
    fhdrCHECKBegin,
    fhdrWAITHeader,
    fhdrWAITClearsig,
    fhdrSKIPHeader,
    fhdrCLEARSIG,
    fhdrREADClearsig,
    fhdrNullClearsig,
    fhdrEMPTYClearsig,
    fhdrCHECKClearsig,
    fhdrCHECKClearsig2,
    fhdrCHECKDashEscaped,
    fhdrCHECKDashEscaped2,
    fhdrCHECKDashEscaped3,
    fhdrREADClearsigNext,
    fhdrENDClearsig,
    fhdrENDClearsigHelp,
    fhdrTESTSpaces,
    fhdrCLEARSIGSimple,
    fhdrCLEARSIGSimpleNext,
    fhdrTEXT,
    fhdrTEXTSimple,
    fhdrERROR,
    fhdrERRORShow,
    fhdrEOF
} fhdr_state_t;


/* if we encounter this armor string with this index, go
 * into a mode which fakes packets and wait for the next armor */
#define BEGIN_SIGNATURE 2
#define BEGIN_SIGNED_MSG_IDX 3
static char *head_strings[] = {
    "BEGIN PGP MESSAGE",
    "BEGIN PGP PUBLIC KEY BLOCK",
    "BEGIN PGP SIGNATURE",
    "BEGIN PGP SIGNED MESSAGE",
    "BEGIN PGP ARMORED FILE",       /* gnupg extension */
    "BEGIN PGP PRIVATE KEY BLOCK",
    "BEGIN PGP SECRET KEY BLOCK",   /* only used by pgp2 */
    NULL
};
static char *tail_strings[] = {
    "END PGP MESSAGE",
    "END PGP PUBLIC KEY BLOCK",
    "END PGP SIGNATURE",
    "END dummy",
    "END PGP ARMORED FILE",
    "END PGP PRIVATE KEY BLOCK",
    "END PGP SECRET KEY BLOCK",
    NULL
};

static void
set_armor_error( const char *msg )
{
    armor_errno = 1;
    strcpy( armor_error, msg );
}

const char*
get_armor_error( void )
{
    if( armor_errno )
        return armor_error;
    return NULL;
}


static unsigned int
check_trailing_chars( const byte *line, unsigned int len,
                      const char *trimchars )
{
    const byte *p, *mark;
    unsigned int n;
    
    for(mark=NULL, p=line, n=0; n < len; n++, p++ ) {
        if( strchr(trimchars, *p ) ) {
            if( !mark )
                mark = p;
        }
        else
            mark = NULL;
    }
    
    if( mark ) {
        return mark - line;
    }
    return len;
}

/****************
 * remove trailing white spaces and return the length of the buffer
 */
static unsigned int
check_trailing_ws( const byte *line, unsigned int len )
{
    return check_trailing_chars( line, len, " \t\r\n" );
}

static unsigned int
trim_trailing_chars( byte *line, unsigned len, const char *trimchars )
{
    byte *p, *mark;
    unsigned n;
    
    for( mark=NULL, p=line, n=0; n < len; n++, p++ ) {
        if( strchr(trimchars, *p ) ) {
            if( !mark )
                mark = p;
        }
        else
            mark = NULL;
    }
    
    if( mark ) {
        *mark = 0;
        return mark - line;
    }
    return len;
}

static void
initialize(void)
{
    int i, j;
    u32 t;
    byte *s;
    
    /* init the crc lookup table */
    crc_table[0] = 0;
    for( i=j=0; j < 128; j++ ) {
        t = crc_table[j];
        if( t & 0x00800000 ) {
            t <<= 1;
            crc_table[i++] = t ^ CRCPOLY;
            crc_table[i++] = t;
        }
        else {
            t <<= 1;
            crc_table[i++] = t;
            crc_table[i++] = t ^ CRCPOLY;
        }
    }
    /* build the helptable for radix64 to bin conversion */
    for( i = 0; i < 256; i++ )
        asctobin[i] = 255; /* used to detect invalid characters */
    for( s = bintoasc, i = 0; *s; s++,i++ )
        asctobin[*s] = i;
    
    is_initialized=1;
}

/****************
 * Check whether this is an armored file or not See also
 * parse-packet.c for details on this code For unknown historic
 * reasons we use a string here but only the first byte will be used.
 * Returns: True if it seems to be armored
 */
static int
is_armored( const byte *buf )
{
    int ctb, pkttype;
    
    ctb = *buf;
    if( !(ctb & 0x80) )
        return 1; /* invalid packet: assume it is armored */
    pkttype =  ctb & 0x40 ? (ctb & 0x3f) : ((ctb>>2)&0xf);
    switch( pkttype ) {
    case PKT_MARKER:
    case PKT_SYMKEY_ENC:
    case PKT_ONEPASS_SIG:
    case PKT_PUBLIC_KEY:
    case PKT_SECRET_KEY:
    case PKT_PUBKEY_ENC:
    case PKT_SIGNATURE:
    case PKT_COMMENT:
    case PKT_OLD_COMMENT:
    case PKT_PLAINTEXT:
    case PKT_COMPRESSED:
    case PKT_ENCRYPTED:
        return 0; /* seems to be a regular packet: not armored */
    }
    
    return 1;
}


/****************
 * Try to check whether the iobuf is armored
 * Returns true if this may be the case; the caller should use the
 *         filter to do further processing.
 */
int
gpg_use_armor_filter( gpg_iobuf_t a )
{
    byte buf[1];
    int n;
    
    /* fixme: there might be a problem with iobuf_peek */
    n = gpg_iobuf_peek(a, buf, 1 );
    if( n == -1 )
        return 0; /* EOF, doesn't matter whether armored or not */
    if( !n )
        return 1; /* can't check it: try armored */
    return is_armored(buf);
}

/****************
 * check whether the armor header is valid on a signed message.
 * this is for security reasons: the header lines are not included in the
 * hash and by using some creative formatting rules, Mallory could fake
 * any text at the beginning of a document; assuming it is read with
 * a simple viewer. We only allow the Hash Header.
 */
static int
parse_hash_header( const char *line )
{
    const char *s, *s2;
    unsigned found = 0;
    
    if( strlen(line) < 6  || strlen(line) > 60 )
        return 0; /* too short or too long */
    if( memcmp( line, "Hash:", 5 ) )
        return 0; /* invalid header */
    s = line+5;
    for( s = line + 5; ; s=s2 ) {
        for(; *s && (*s==' ' || *s == '\t'); s++ )
            ;
        if( !*s )
            break;
        for(s2=s+1; *s2 && *s2!=' ' && *s2 != '\t' && *s2 != ','; s2++ )
            ;
        if( !strncmp( s, "RIPEMD160", s2-s ) )
            found |= 1;
        else if( !strncmp( s, "SHA1", s2-s ) )
            found |= 2;
        else if( !strncmp( s, "MD5", s2-s ) )
            found |= 4;
        else if( !strncmp( s, "TIGER192", s2-s ) )
            found |= 8;
        else if( !strncmp( s, "TIGER", s2-s ) ) /* used by old versions */
            found |= 8;
        else
            return 0;
        for(; *s2 && (*s2==' ' || *s2 == '\t'); s2++ )
            ;
        if( *s2 && *s2 != ',' )
            return 0;
        if( *s2 )
            s2++;
    }
    return found;
}


/****************
 * Check whether this is a armor line.
 * returns: -1 if it is not a armor header or the index number of the
 * armor header.
 */
static int
is_armor_header( byte *line, unsigned len )
{
    const char *s;
    byte *save_p, *p;
    int save_c;
    int i;
    
    if( len < 15 )
        return -1; /* too short */
    if( memcmp( line, "-----", 5 ) )
        return -1; /* no */
    p = strstr( line+5, "-----");
    if( !p )
        return -1;
    save_p = p;
    p += 5;
    
    /* Some mail programs on Windows seem to add spaces to the end of
       the line.  This becomes strict if --openpgp is set. */
    
#if 0
    if(!opt.rfc2440)
        while(*p==' ')
            p++;
#endif
    
    if( *p == '\r' )
        p++;
    if( *p == '\n' )
        p++;
    if( *p )
        return -1; /* garbage after dashes */
    save_c = *save_p; *save_p = 0;
    p = line+5;
    for(i=0; (s=head_strings[i]); i++ )
        if( !strcmp(s, p) )
            break;
    *save_p = save_c;
    if( !s )
        return -1; /* unknown armor line */
    
    return i;
}

void
print_string( FILE *fp, const byte *p, size_t n, int delim )
{
    for( ; n; n--, p++ )
        if( *p < 0x20 || (*p >= 0x7f && *p < 0xa0) || *p == delim ||
            (delim && *p=='\\')) {
            putc('\\', fp);
            if( *p == '\n' )
                putc('n', fp);
            else if( *p == '\r' )
                putc('r', fp);
            else if( *p == '\f' )
                putc('f', fp);
            else if( *p == '\v' )
                putc('v', fp);
            else if( *p == '\b' )
                putc('b', fp);
            else if( !*p )
                putc('0', fp);
            else
                fprintf(fp, "x%02x", *p );
        }
        else
            putc(*p, fp);
}

/****************
 * Parse a header lines
 * Return 0: Empty line (end of header lines)
 *       -1: invalid header line
 *       >0: Good header line
 */
static int
parse_header_line( armor_filter_context_t *afx, byte *line, unsigned int len )
{
    byte *p;
    int hashes=0;
    unsigned int len2;
    
    len2 = check_trailing_ws( line, len );
    if( !len2 ) {
        afx->buffer_pos = len2;  /* (it is not the fine way to do it here) */
        return 0; /* WS only: same as empty line */
    }
    len = len2;
    line[len2] = 0;
    
    p = strchr( line, ':');
    if( !p || !p[1] ) {
        set_armor_error("invalid armor header: ");
        print_string( stderr, line, len, 0 );
        putc('\n', stderr);
        return -1;
    }    
    
    if( afx->in_cleartext ) {
        if( (hashes=parse_hash_header( line )) )
            afx->hashes |= hashes;
        else if( strlen(line) > 15 && !memcmp( line, "NotDashEscaped:", 15 ) )
            afx->not_dash_escaped = 1;
        else {
            set_armor_error("invalid clearsig header\n");
            return -1;
        }
    }
    return 1;
}


/* figure out whether the data is armored or not */
static int
check_input( armor_filter_context_t *afx, gpg_iobuf_t a )
{
    int rc = 0;
    int i;
    byte *line;
    unsigned len;
    unsigned maxlen;
    int hdr_line = -1;
    
    /* read the first line to see whether this is armored data */
    maxlen = MAX_LINELEN;
    len = afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                             &afx->buffer_size, &maxlen );
    line = afx->buffer;
    if( !maxlen ) {
        /* line has been truncated: assume not armored */
        afx->inp_checked = 1;
        afx->inp_bypass = 1;
        return 0;
    }
    
    if( !len ) {
        return -1; /* eof */
    }
    
    /* (the line is always a C string but maybe longer) */
    if( *line == '\n' || ( len && (*line == '\r' && line[1]=='\n') ) )
        ;
    else if( !is_armored( line ) ) {
        afx->inp_checked = 1;
        afx->inp_bypass = 1;
        return 0;
    }
    
    /* find the armor header */
    while(len) {
        i = is_armor_header( line, len );
        if( i >= 0 && !(afx->only_keyblocks && i != 1 && i != 5 && i != 6 )) {
            hdr_line = i;
            if( hdr_line == BEGIN_SIGNED_MSG_IDX ) {
                if( afx->in_cleartext ) {
                    set_armor_error("nested clear text signatures\n");
                    rc = G10ERR_INVALID_ARMOR;
                }
                afx->in_cleartext = 1;
            }
            break;
        }
        /* read the next line (skip all truncated lines) */
        do {
            maxlen = MAX_LINELEN;
            afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                               &afx->buffer_size, &maxlen );
            line = afx->buffer;
            len = afx->buffer_len;
        } while( !maxlen );
    }
    
    /* parse the header lines */
    while(len) {
        /* read the next line (skip all truncated lines) */
        do {
            maxlen = MAX_LINELEN;
            afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                               &afx->buffer_size, &maxlen );
            line = afx->buffer;
            len = afx->buffer_len;
        } while( !maxlen );
        
        i = parse_header_line( afx, line, len );
        if( i <= 0 ) {
            if( i )
                rc = G10ERR_INVALID_ARMOR;
            break;
        }
    }

    if( afx->in_cleartext )
        afx->faked = 1;
    else {
        afx->inp_checked = 1;
        afx->crc = CRCINIT;
        afx->idx = 0;
        afx->radbuf[0] = 0;
    }
    
    return rc;
}


/****************
 * Fake a literal data packet and wait for the next armor line
 * fixme: empty line handling and null length clear text signature are
 *        not implemented/checked.
 */
static int
fake_packet( armor_filter_context_t *afx, gpg_iobuf_t a,
             size_t *retn, byte *buf, size_t size  )
{
    int rc = 0;
    size_t len = 0;
    int lastline = 0;
    unsigned maxlen, n;
    byte *p;
    
    len = 2;    /* reserve 2 bytes for the length header */
    size -= 2;  /* and 2 for the terminating header */
    while( !rc && len < size ) {
        /* copy what we have in the line buffer */
        if( afx->faked == 1 )
            afx->faked++; /* skip the first (empty) line */
        else {
            while( len < size && afx->buffer_pos < afx->buffer_len )
                buf[len++] = afx->buffer[afx->buffer_pos++];
            if( len >= size )
                continue;
        }
        
        /* read the next line */
        maxlen = MAX_LINELEN;
        afx->buffer_pos = 0;
        afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                           &afx->buffer_size, &maxlen );
        if( !afx->buffer_len ) {
            rc = -1; /* eof (should not happen) */
            continue;
        }
        if( !maxlen )
            afx->truncated++;
        if( !afx->not_dash_escaped ) {
            int crlf;
            p = afx->buffer;
            n = afx->buffer_len;
            crlf = n > 1 && p[n-2] == '\r' && p[n-1]=='\n';
            
            /* PGP2 does not treat a tab as white space character */
            afx->buffer_len = trim_trailing_chars( p, n,
                                                   afx->pgp2mode ? " \r\n" : " \t\r\n");
            /* the buffer is always allocated with enough space to append
             * the removed [CR], LF and a Nul
             * The reason for this complicated procedure is to keep at least
             * the original type of lineending - handling of the removed
             * trailing spaces seems to be impossible in our method
             * of faking a packet; either we have to use a temporary file
             * or calculate the hash here in this module and somehow find
             * a way to send the hash down the processing line (well, a special
             * faked packet could do the job).
             */
            if( crlf )
                afx->buffer[afx->buffer_len++] = '\r';
            afx->buffer[afx->buffer_len++] = '\n';
            afx->buffer[afx->buffer_len] = 0;
        }
        p = afx->buffer;
        n = afx->buffer_len;
        
        if( n > 2 && *p == '-' ) {
            /* check for dash escaped or armor header */
            if( p[1] == ' ' && !afx->not_dash_escaped ) {
                /* issue a warning if it is not regular encoded */
                if( p[2] != '-' && !( n > 6 && !memcmp(p+2, "From ", 5))) {
                    set_armor_error("invalid dash escaped line: ");
                    print_string( stderr, p, n, 0 );
                    putc('\n', stderr);
                }
                afx->buffer_pos = 2; /* skip */
            }
            else if( n >= 15 &&  p[1] == '-' && p[2] == '-' && p[3] == '-' ) {
                int type = is_armor_header( p, n );
                if( afx->not_dash_escaped && type != BEGIN_SIGNATURE )
                    ; /* this is okay */
                else {
                    if( type != BEGIN_SIGNATURE ) {
                        set_armor_error("unexpected armor:");
                        print_string( stderr, p, n, 0 );
                        putc('\n', stderr);
                    }
                    lastline = 1;
                    rc = -1;
                }
            }
        }
    }
    
    buf[0] = (len-2) >> 8;
    buf[1] = (len-2);
    if( lastline ) { /* write last (ending) length header */
        if( buf[0] || buf[1] ) { /* only if we have some text */
            buf[len++] = 0;
            buf[len++] = 0;
        }
        rc = 0;
        afx->faked = 0;
        afx->in_cleartext = 0;
        /* and now read the header lines */
        afx->buffer_pos = 0;
        for(;;) {
            int i;
            
            /* read the next line (skip all truncated lines) */
            do {
                maxlen = MAX_LINELEN;
                afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                                   &afx->buffer_size, &maxlen );
            } while( !maxlen );
            p = afx->buffer;
            n = afx->buffer_len;
            if( !n ) {
                rc = -1;
                break; /* eof */
            }
            i = parse_header_line( afx, p , n );
            if( i <= 0 ) {
                if( i )
                    MessageBox( NULL, "Invalid ARMOR detected", "Error", MB_OK );
                break;
            }
        }
        afx->inp_checked = 1;
        afx->crc = CRCINIT;
        afx->idx = 0;
        afx->radbuf[0] = 0;
    }
    
    *retn = len;
    return rc;
}


static int
invalid_crc(void)
{        
    return G10ERR_INVALID_ARMOR;
}


static int
radix64_read( armor_filter_context_t *afx, gpg_iobuf_t a, size_t *retn,
              byte *buf, size_t size )
{
    byte val;
    int c=0, c2; /*init c because gcc is not clever enough for the continue*/
    int checkcrc=0;
    int rc = 0;
    size_t n = 0;
    int  idx, i;
    u32 crc;
    
    crc = afx->crc;
    idx = afx->idx;
    val = afx->radbuf[0];
    for( n=0; n < size; ) {
        
        if( afx->buffer_pos < afx->buffer_len )
            c = afx->buffer[afx->buffer_pos++];
        else { /* read the next line */
            unsigned maxlen = MAX_LINELEN;
            afx->buffer_pos = 0;
            afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                               &afx->buffer_size, &maxlen );
            if( !maxlen )
                afx->truncated++;
            if( !afx->buffer_len )
                break; /* eof */
            continue;
        }
        
    again:
        if( c == '\n' || c == ' ' || c == '\r' || c == '\t' )
            continue;
        else if( c == '=' ) { /* pad character: stop */
            /* some mailers leave quoted-printable encoded characters
             * so we try to workaround this */
            if( afx->buffer_pos+2 < afx->buffer_len ) {
                int cc1, cc2, cc3;
                cc1 = afx->buffer[afx->buffer_pos];
                cc2 = afx->buffer[afx->buffer_pos+1];
                cc3 = afx->buffer[afx->buffer_pos+2];
                if( isxdigit(cc1) && isxdigit(cc2)
                    && strchr( "=\n\r\t ", cc3 )) {
                    /* well it seems to be the case - adjust */
                    c = isdigit(cc1)? (cc1 - '0'): (toupper(cc1)-'A'+10);
                    c <<= 4;
                    c |= isdigit(cc2)? (cc2 - '0'): (toupper(cc2)-'A'+10);
                    afx->buffer_pos += 2;
                    afx->qp_detected = 1;
                    goto again;
                }
            }
            
            if( idx == 1 )
                buf[n++] = val;
            checkcrc++;
            break;
        }
        else if( (c = asctobin[(c2=c)]) == 255 ) {
            char msg[128];
            _snprintf( msg, sizeof msg-1, "invalid radix64 character %02x skipped\n", c2);
            set_armor_error( msg );
            continue;
        }
        switch(idx) {
        case 0: val =  c << 2; break;
        case 1: val |= (c>>4)&3; buf[n++]=val;val=(c<<4)&0xf0;break;
        case 2: val |= (c>>2)&15; buf[n++]=val;val=(c<<6)&0xc0;break;
        case 3: val |= c&0x3f; buf[n++] = val; break;
        }
        idx = (idx+1) % 4;
    }
    
    for(i=0; i < n; i++ )
        crc = (crc << 8) ^ crc_table[((crc >> 16)&0xff) ^ buf[i]];
    crc &= 0x00ffffff;
    afx->crc = crc;
    afx->idx = idx;
    afx->radbuf[0] = val;
    
    if( checkcrc ) {
        afx->any_data = 1;
        afx->inp_checked=0;
        afx->faked = 0;
        for(;;) { /* skip lf and pad characters */
            if( afx->buffer_pos < afx->buffer_len )
                c = afx->buffer[afx->buffer_pos++];
            else { /* read the next line */
                unsigned maxlen = MAX_LINELEN;
                afx->buffer_pos = 0;
                afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                                   &afx->buffer_size, &maxlen );
                if( !maxlen )
                    afx->truncated++;
                if( !afx->buffer_len )
                    break; /* eof */
                continue;
            }
            if( c == '\n' || c == ' ' || c == '\r'
                || c == '\t' || c == '=' )
                continue;
            break;
        }
        if( c == -1 )
            set_armor_error("premature eof (no CRC)\n");
        else {
            u32 mycrc = 0;
            idx = 0;
            do {
                if( (c = asctobin[c]) == 255 )
                    break;
                switch(idx) {
                case 0: val =  c << 2; break;
                case 1: val |= (c>>4)&3; mycrc |= val << 16;val=(c<<4)&0xf0;break;
                case 2: val |= (c>>2)&15; mycrc |= val << 8;val=(c<<6)&0xc0;break;
                case 3: val |= c&0x3f; mycrc |= val; break;
                }
                for(;;) {
                    if( afx->buffer_pos < afx->buffer_len )
                        c = afx->buffer[afx->buffer_pos++];
                    else { /* read the next line */
                        unsigned maxlen = MAX_LINELEN;
                        afx->buffer_pos = 0;
                        afx->buffer_len = gpg_iobuf_read_line( a, &afx->buffer,
                                                           &afx->buffer_size,
                                                           &maxlen );
                        if( !maxlen )
                            afx->truncated++;
                        if( !afx->buffer_len )
                            break; /* eof */
                        continue;
                    }
                    break;
                }
                if( !afx->buffer_len )
                    break; /* eof */
            } while( ++idx < 4 );
            if( c == -1 ) {
                set_armor_error("premature eof (in CRC)\n");
                rc = invalid_crc();
            }
            else if( idx != 4 ) {
                set_armor_error("malformed CRC\n");
                rc = invalid_crc();
            }
            else if( mycrc != afx->crc ) {
                char msg[128];
                _snprintf( msg, sizeof msg-1,
                 "CRC error; %06lx - %06lx\n",
                        (ulong)afx->crc, (ulong)mycrc);
                set_armor_error( msg );
                rc = invalid_crc();
            }
            else {
                rc = 0;
            }
        }
    }
    
    if( !n )
        rc = -1;
    
    *retn = n;
    return rc;
}

/****************
 * This filter is used to handle the armor stuff
 */
int
gpg_armor_filter( void *opaque, int control,
                  gpg_iobuf_t a, byte *buf, size_t *ret_len)
{
    size_t size = *ret_len;
    armor_filter_context_t *afx = opaque;
    int rc=0, i, c;
    byte radbuf[3];
    int  idx, idx2;
    size_t n=0;
    u32 crc;  
    
    if( control == IOBUFCTRL_UNDERFLOW && afx->inp_bypass ) {
        n = 0;
        if( afx->buffer_len ) {
            for(; n < size && afx->buffer_pos < afx->buffer_len; n++ )
                buf[n++] = afx->buffer[afx->buffer_pos++];
            if( afx->buffer_pos >= afx->buffer_len )
                afx->buffer_len = 0;
        }
        for(; n < size; n++ ) {
            if( (c=gpg_iobuf_get(a)) == -1 )
                break;
            buf[n] = c & 0xff;
        }
        if( !n )
            rc = -1;
        *ret_len = n;
    }
    else if( control == IOBUFCTRL_UNDERFLOW ) {
        /* We need some space for the faked packet.  The minmum required
         * size is ~18 + length of the session marker */
        if( size < 50 ) {
            printf( "This is a BUG.\n%s:%d\n", __FILE__, __LINE__ );
            exit( -1 ); /* supplied buffer too short */
        }
        if( afx->faked )
            rc = fake_packet( afx, a, &n, buf, size );
        else if( !afx->inp_checked ) {
            rc = check_input( afx, a );
            if( afx->inp_bypass ) {
                for(n=0; n < size && afx->buffer_pos < afx->buffer_len; )
                    buf[n++] = afx->buffer[afx->buffer_pos++];
                if( afx->buffer_pos >= afx->buffer_len )
                    afx->buffer_len = 0;
                if( !n )
                    rc = -1;
            }
            else if( afx->faked ) {
                unsigned int hashes = afx->hashes;
                const byte *sesmark;
                size_t sesmarklen;
                
                sesmark = get_session_marker( &sesmarklen );
                if ( sesmarklen > 20 ) {
                    printf( "This is a BUG.\n%s:%d\n", __FILE__, __LINE__ );
                    exit( -1 );
                }
                /* the buffer is at least 15+n*15 bytes long, so it
                 * is easy to construct the packets */
                
                hashes &= 1|2|4|8;
                if( !hashes ) {
                    hashes |= 4;  /* default to MD 5 */
                    afx->pgp2mode = 1;
                }
                n=0;
                /* first a gpg control packet */
                buf[n++] = 0xff; /* new format, type 63, 1 length byte */
                n++;   /* see below */
                memcpy(buf+n, sesmark, sesmarklen ); n+= sesmarklen;
                buf[n++] = CTRLPKT_CLEARSIGN_START; 
                buf[n++] = afx->not_dash_escaped? 0:1; /* sigclass */
                if( hashes & 1 ) 
                    buf[n++] = DIGEST_ALGO_RMD160;
                if( hashes & 2 ) 
                    buf[n++] = DIGEST_ALGO_SHA1;
                if( hashes & 4 ) 
                    buf[n++] = DIGEST_ALGO_MD5;
                buf[1] = n - 2;
                
                /* followed by a plaintext packet */
                buf[n++] = 0xaf; /* old packet format, type 11, var length */
                buf[n++] = 0;    /* set the length header */
                buf[n++] = 6;
                buf[n++] = 't';  /* canonical text mode */
                buf[n++] = 0;    /* namelength */
                memset(buf+n, 0, 4); /* timestamp */
                n += 4;
            }
            else if( !rc )
                rc = radix64_read( afx, a, &n, buf, size );
        }
        else
            rc = radix64_read( afx, a, &n, buf, size );      
        *ret_len = n;
    }
    else if( control == IOBUFCTRL_FLUSH && !afx->cancel ) {
        /* we don't need this ;-) */
    }
    else if( control == IOBUFCTRL_INIT ) {
        if( !is_initialized )
            initialize();
    }
    else if( control == IOBUFCTRL_CANCEL ) {
        afx->cancel = 1;
    }
    else if( control == IOBUFCTRL_FREE ) {
        if( afx->cancel )
            ;
        else if( afx->status ) { /* pad, write cecksum, and bottom line */
            crc = afx->crc;
            idx = afx->idx;
            idx2 = afx->idx2;
            for(i=0; i < idx; i++ )
                radbuf[i] = afx->radbuf[i];
            if( idx ) {
                c = bintoasc[(*radbuf>>2)&077];
                gpg_iobuf_put(a, c);
                if( idx == 1 ) {
                    c = bintoasc[((*radbuf << 4) & 060) & 077];
                    gpg_iobuf_put(a, c);
                    gpg_iobuf_put(a, '=');
                    gpg_iobuf_put(a, '=');
                }
                else { /* 2 */
                    c = bintoasc[(((*radbuf<<4)&060)|((radbuf[1]>>4)&017))&077];
                    gpg_iobuf_put(a, c);
                    c = bintoasc[((radbuf[1] << 2) & 074) & 077];
                    gpg_iobuf_put(a, c);
                    gpg_iobuf_put(a, '=');
                }
                if( ++idx2 >= (64/4) ) { /* pgp doesn't like 72 here */
                    gpg_iobuf_writestr(a, LF );
                    idx2=0;
                }
            }
            /* may need a linefeed */
            if( idx2 )
                gpg_iobuf_writestr(a, LF );
            /* write the CRC */
            gpg_iobuf_put(a, '=');
            radbuf[0] = crc >>16;
            radbuf[1] = crc >> 8;
            radbuf[2] = crc;
            c = bintoasc[(*radbuf >> 2) & 077];
            gpg_iobuf_put(a, c);
            c = bintoasc[(((*radbuf<<4)&060)|((radbuf[1] >> 4)&017))&077];
            gpg_iobuf_put(a, c);
            c = bintoasc[(((radbuf[1]<<2)&074)|((radbuf[2]>>6)&03))&077];
            gpg_iobuf_put(a, c);
            c = bintoasc[radbuf[2]&077];
            gpg_iobuf_put(a, c);
            gpg_iobuf_writestr(a, LF );
            /* and the the trailer */
            if( afx->what >= DIM(tail_strings) )
                printf("afx->what=%d", afx->what);
            gpg_iobuf_writestr(a, "-----");
            gpg_iobuf_writestr(a, tail_strings[afx->what] );
            gpg_iobuf_writestr(a, "-----" LF );
        }
        else if( !afx->any_data && !afx->inp_bypass ) {
            set_armor_error("no valid OpenPGP data found.\n");
            afx->no_openpgp_data = 1;
            printf( "[GNUPG:] NODATA 1" );          
        }
        if( afx->truncated ) {
            char msg[128];
            _snprintf( msg, sizeof msg-1, "invalid armor: line longer than %d characters\n",                   MAX_LINELEN );
            set_armor_error( msg );
        }
        /* issue an error to enforce dissemination of correct software */
        if( afx->qp_detected )
            set_armor_error("quoted printable character in armor - "
                     "probably a buggy MTA has been used\n" );
        safe_free( afx->buffer );
        afx->buffer = NULL;
    }
    else if( control == IOBUFCTRL_DESC )
        *(char**)buf = "armor_filter";
    return rc;
}

/***********************************************
 *  For the pipemode command we can't use the armor filter for various
 *  reasons, so we use this new unarmor_pump stuff to remove the armor 
 */

enum unarmor_state_e {
    STA_init = 0,
    STA_bypass,
    STA_wait_newline,
    STA_wait_dash,
    STA_first_dash, 
    STA_compare_header,
    STA_found_header_wait_newline,
    STA_skip_header_lines,
    STA_skip_header_lines_non_ws,
    STA_read_data,
    STA_wait_crc,
    STA_read_crc,
    STA_ready
};

struct unarmor_pump_s {
    enum unarmor_state_e state;
    byte val;
    int checkcrc;
    int pos;   /* counts from 0..3 */
    u32 crc;
    u32 mycrc; /* the one store in the data */
};


UnarmorPump
unarmor_pump_new (void)
{
    UnarmorPump x;
    
    if( !is_initialized )
        initialize();
    x = calloc (1, sizeof *x);
    return x;
}

void
unarmor_pump_release (UnarmorPump x)
{
    safe_free (x);
}

/* 
 * Get the next character from the ascii armor taken from the gpg_iobuf_t
 * created earlier by unarmor_pump_new().
 * Return:  c = Character
 *        256 = ignore this value
 *         -1 = End of current armor 
 *         -2 = Premature EOF (not used)
 *         -3 = Invalid armor
 */
int
unarmor_pump (UnarmorPump x, int c)
{
    int rval = 256; /* default is to ignore the return value */
    
    switch (x->state) {
    case STA_init:
    { 
        byte tmp[1];
        tmp[0] = c; 
        if ( is_armored (tmp) )
            x->state = c == '-'? STA_first_dash : STA_wait_newline;
        else {
            x->state = STA_bypass;
            return c;
        }
    }
    break;
    case STA_bypass:
        return c; /* return here to avoid crc calculation */
    case STA_wait_newline:
        if (c == '\n')
            x->state = STA_wait_dash;
        break;
    case STA_wait_dash:
        x->state = c == '-'? STA_first_dash : STA_wait_newline;
        break;
    case STA_first_dash: /* just need for initalization */
        x->pos = 0;
        x->state = STA_compare_header;
    case STA_compare_header:
        if ( "-----BEGIN PGP SIGNATURE-----"[++x->pos] == c ) {
            if ( x->pos == 28 ) 
                x->state = STA_found_header_wait_newline;
        }
        else 
            x->state = c == '\n'? STA_wait_dash : STA_wait_newline;
        break;
    case STA_found_header_wait_newline:
        /* to make CR,LF issues easier we simply allow for white space
           behind the 5 dashes */
        if ( c == '\n' )
            x->state = STA_skip_header_lines;
        else if ( c != '\r' && c != ' ' && c != '\t' )
            x->state = STA_wait_dash; /* garbage after the header line */
        break;
    case STA_skip_header_lines:
        /* i.e. wait for one empty line */
        if ( c == '\n' ) {
            x->state = STA_read_data;
            x->crc = CRCINIT;
            x->val = 0;
            x->pos = 0;
        }
        else if ( c != '\r' && c != ' ' && c != '\t' )
            x->state = STA_skip_header_lines_non_ws;
        break;
    case STA_skip_header_lines_non_ws:
        /* like above but we already encountered non white space */
        if ( c == '\n' )
            x->state = STA_skip_header_lines;
        break;
    case STA_read_data:
        /* fixme: we don't check for the trailing dash lines but rely
         * on the armor stop characters */
        if( c == '\n' || c == ' ' || c == '\r' || c == '\t' )
            break; /* skip all kind of white space */
        
        if( c == '=' ) { /* pad character: stop */
            if( x->pos == 1 ) /* in this case val has some value */
                rval = x->val;
            x->state = STA_wait_crc;
            break;
        }
        
        {
            int c2;
            if( (c = asctobin[(c2=c)]) == 255 ) {
                char msg[128];
                _snprintf( msg, sizeof msg-1, "invalid radix64 character %02x skipped\n", c2);
                set_armor_error( msg );
                break;
            }
        }
        
        switch(x->pos) {
        case 0:
            x->val = c << 2;
            break;
        case 1:
            x->val |= (c>>4)&3;
            rval = x->val;
            x->val = (c<<4)&0xf0;
            break;
        case 2:
            x->val |= (c>>2)&15;
            rval = x->val;
            x->val = (c<<6)&0xc0;
            break;
        case 3:
            x->val |= c&0x3f;
            rval = x->val;
            break;
        }
        x->pos = (x->pos+1) % 4;
        break;
    case STA_wait_crc:
        if( c == '\n' || c == ' ' || c == '\r' || c == '\t' || c == '=' )
            break; /* skip ws and pad characters */
        /* assume that we are at the next line */
        x->state = STA_read_crc;
        x->pos = 0;
        x->mycrc = 0;
    case STA_read_crc:
        if( (c = asctobin[c]) == 255 ) {
            rval = -1; /* ready */
            if( x->crc != x->mycrc ) {
                char msg[128];
                _snprintf( msg, sizeof msg-1, "CRC error; %06lx - %06lx\n",
                        (ulong)x->crc, (ulong)x->mycrc);
                set_armor_error( msg );
                if ( invalid_crc() )
                    rval = -3;
            }
            x->state = STA_ready; /* not sure whether this is correct */
            break;
        }
        
        switch(x->pos) {
        case 0:
            x->val = c << 2;
            break;
        case 1:
            x->val |= (c>>4)&3;
            x->mycrc |= x->val << 16;
            x->val = (c<<4)&0xf0;
            break;
        case 2:
            x->val |= (c>>2)&15;
            x->mycrc |= x->val << 8;
            x->val = (c<<6)&0xc0;
            break;
        case 3:
            x->val |= c&0x3f;
            x->mycrc |= x->val;
            break;
        }
        x->pos = (x->pos+1) % 4;
        break;
    case STA_ready:
        rval = -1;
        break;
    }
    
    if ( !(rval & ~255) ) { /* compute the CRC */
        x->crc = (x->crc << 8) ^ crc_table[((x->crc >> 16)&0xff) ^ rval];
        x->crc &= 0x00ffffff;
    }
    
    return rval;
}

