armor.c
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armor.c
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	/* armor.c - Armor flter
	* 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
	*/

	#include <config.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <assert.h>
	#include <ctype.h>

	#include "errors.h"
	#include "iobuf.h"
	#include "memory.h"
	#include "util.h"
	#include "filter.h"
	#include "packet.h"
	#include "options.h"
	#include "main.h"
	#include "status.h"
	#include "i18n.h"

	#ifdef HAVE_DOSISH_SYSTEM
	#define LF "\r\n"
	#else
	#define LF "\n"
	#endif

	#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;


	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
	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
	use_armor_filter( IOBUF a )
	{
	byte buf[1];
	int n;

	/* fixme: there might be a problem with iobuf_peek */
	n = 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);
	}




	static void
	invalid_armor(void)
	{
	write_status(STATUS_BADARMOR);
	g10_exit(1); /* stop here */
	}


	/****************
	* 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(!opt.rfc2440)
	while(*p==' ')
	p++;

	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 */

	if( opt.verbose > 1 )
	log_info(_("armor: %s\n"), head_strings[i]);
	return i;
	}



	/****************
	* 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] ) {
	log_error(_("invalid armor header: "));
	print_string( stderr, line, len, 0 );
	putc('\n', stderr);
	return -1;
	}

	if( opt.verbose ) {
	log_info(_("armor header: "));
	print_string( stderr, line, len, 0 );
	putc('\n', stderr);
	}

	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 {
	log_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, IOBUF 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 = 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 ) {
	log_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 = 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 = 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( rc )
	invalid_armor();
	else 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, IOBUF 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 = 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))) {
	log_info(_("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 ) {
	log_info(_("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 = 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 )
	invalid_armor();
	break;
	}
	}
	afx->inp_checked = 1;
	afx->crc = CRCINIT;
	afx->idx = 0;
	afx->radbuf[0] = 0;
	}

	*retn = len;
	return rc;
	}


	static int
	invalid_crc(void)
	{
	if ( opt.ignore_crc_error )
	return 0;
	log_inc_errorcount();
	return G10ERR_INVALID_ARMOR;
	}


	static int
	radix64_read( armor_filter_context_t afx, IOBUF 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 = 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'): (ascii_toupper(cc1)-'A'+10);
	c <<= 4;
	c \|= isdigit(cc2)? (cc2 - '0'): (ascii_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 ) {
	log_error(_("invalid radix64 character %02x skipped\n"), c2);
	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 = 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 )
	log_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 = 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 ) {
	log_info(_("premature eof (in CRC)\n"));
	rc = invalid_crc();
	}
	else if( idx != 4 ) {
	log_info(_("malformed CRC\n"));
	rc = invalid_crc();
	}
	else if( mycrc != afx->crc ) {
	log_info (_("CRC error; %06lx - %06lx\n"),
	(ulong)afx->crc, (ulong)mycrc);
	rc = invalid_crc();
	}
	else {
	rc = 0;
	/* FIXME: Here we should emit another control packet,
	* so that we know in mainproc that we are processing
	* a clearsign message */
	#if 0
	for(rc=0;!rc;) {
	rc = 0 /check_trailer( &fhdr, c )/;
	if( !rc ) {
	if( (c=iobuf_get(a)) == -1 )
	rc = 2;
	}
	}
	if( rc == -1 )
	rc = 0;
	else if( rc == 2 ) {
	log_error(_("premature eof (in Trailer)\n"));
	rc = G10ERR_INVALID_ARMOR;
	}
	else {
	log_error(_("error in trailer line\n"));
	rc = G10ERR_INVALID_ARMOR;
	}
	#endif
	}
	}
	}

	if( !n )
	rc = -1;

	*retn = n;
	return rc;
	}

	/****************
	* This filter is used to handle the armor stuff
	*/
	int
	armor_filter( void *opaque, int control,
	IOBUF 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 0
	static FILE *fp ;

	if( !fp ) {
	fp = fopen("armor.out", "w");
	assert(fp);
	}
	#endif

	if( DBG_FILTER )
	log_debug("armor-filter: control: %d\n", control );
	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=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 )
	BUG(); /* 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 )
	BUG();

	/* 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 */
	if( opt.pgp2_workarounds )
	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;
	if( hashes & 8 )
	buf[n++] = DIGEST_ALGO_TIGER;
	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 );
	#if 0
	if( n )
	if( fwrite(buf, n, 1, fp ) != 1 )
	BUG();
	#endif
	*ret_len = n;
	}
	else if( control == IOBUFCTRL_FLUSH && !afx->cancel ) {
	if( !afx->status ) { /* write the header line */
	const char *s;

	if( afx->what >= DIM(head_strings) )
	log_bug("afx->what=%d", afx->what);
	iobuf_writestr(a, "-----");
	iobuf_writestr(a, head_strings[afx->what] );
	iobuf_writestr(a, "-----" LF );
	if( !opt.no_version )
	iobuf_writestr(a, "Version: GnuPG v" VERSION " ("
	PRINTABLE_OS_NAME ")" LF );

	/* write the comment string or a default one */
	s = opt.comment_string;
	if( s && *s ) {
	iobuf_writestr(a, "Comment: " );
	for( ; *s; s++ ) {
	if( *s == '\n' )
	iobuf_writestr(a, "\\n" );
	else if( *s == '\r' )
	iobuf_writestr(a, "\\r" );
	else if( *s == '\v' )
	iobuf_writestr(a, "\\v" );
	else
	iobuf_put(a, *s );
	}
	iobuf_writestr(a, LF );
	}

	if ( afx->hdrlines ) {
	for ( s = afx->hdrlines; *s; s++ ) {
	#ifdef HAVE_DOSISH_SYSTEM
	if ( *s == '\n' )
	iobuf_put( a, '\r');
	#endif
	iobuf_put(a, *s );
	}
	}
	iobuf_writestr(a, LF );
	afx->status++;
	afx->idx = 0;
	afx->idx2 = 0;
	afx->crc = CRCINIT;

	}
	crc = afx->crc;
	idx = afx->idx;
	idx2 = afx->idx2;
	for(i=0; i < idx; i++ )
	radbuf[i] = afx->radbuf[i];

	for(i=0; i < size; i++ )
	crc = (crc << 8) ^ crc_table[((crc >> 16)&0xff) ^ buf[i]];
	crc &= 0x00ffffff;

	for( ; size; buf++, size-- ) {
	radbuf[idx++] = *buf;
	if( idx > 2 ) {
	idx = 0;
	c = bintoasc[(*radbuf >> 2) & 077];
	iobuf_put(a, c);
	c = bintoasc[(((*radbuf<<4)&060)\|((radbuf[1] >> 4)&017))&077];
	iobuf_put(a, c);
	c = bintoasc[(((radbuf[1]<<2)&074)\|((radbuf[2]>>6)&03))&077];
	iobuf_put(a, c);
	c = bintoasc[radbuf[2]&077];
	iobuf_put(a, c);
	if( ++idx2 >= (64/4) ) { /* pgp doesn't like 72 here */
	iobuf_writestr(a, LF );
	idx2=0;
	}
	}
	}
	for(i=0; i < idx; i++ )
	afx->radbuf[i] = radbuf[i];
	afx->idx = idx;
	afx->idx2 = idx2;
	afx->crc = crc;
	}
	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];
	iobuf_put(a, c);
	if( idx == 1 ) {
	c = bintoasc[((*radbuf << 4) & 060) & 077];
	iobuf_put(a, c);
	iobuf_put(a, '=');
	iobuf_put(a, '=');
	}
	else { /* 2 */
	c = bintoasc[(((*radbuf<<4)&060)\|((radbuf[1]>>4)&017))&077];
	iobuf_put(a, c);
	c = bintoasc[((radbuf[1] << 2) & 074) & 077];
	iobuf_put(a, c);
	iobuf_put(a, '=');
	}
	if( ++idx2 >= (64/4) ) { /* pgp doesn't like 72 here */
	iobuf_writestr(a, LF );
	idx2=0;
	}
	}
	/* may need a linefeed */
	if( idx2 )
	iobuf_writestr(a, LF );
	/* write the CRC */
	iobuf_put(a, '=');
	radbuf[0] = crc >>16;
	radbuf[1] = crc >> 8;
	radbuf[2] = crc;
	c = bintoasc[(*radbuf >> 2) & 077];
	iobuf_put(a, c);
	c = bintoasc[(((*radbuf<<4)&060)\|((radbuf[1] >> 4)&017))&077];
	iobuf_put(a, c);
	c = bintoasc[(((radbuf[1]<<2)&074)\|((radbuf[2]>>6)&03))&077];
	iobuf_put(a, c);
	c = bintoasc[radbuf[2]&077];
	iobuf_put(a, c);
	iobuf_writestr(a, LF );
	/* and the the trailer */
	if( afx->what >= DIM(tail_strings) )
	log_bug("afx->what=%d", afx->what);
	iobuf_writestr(a, "-----");
	iobuf_writestr(a, tail_strings[afx->what] );
	iobuf_writestr(a, "-----" LF );
	}
	else if( !afx->any_data && !afx->inp_bypass ) {
	log_error(_("no valid OpenPGP data found.\n"));
	afx->no_openpgp_data = 1;
	write_status_text( STATUS_NODATA, "1" );
	}
	if( afx->truncated )
	log_info(_("invalid armor: line longer than %d characters\n"),
	MAX_LINELEN );
	/* issue an error to enforce dissemination of correct software */
	if( afx->qp_detected )
	log_error(_("quoted printable character in armor - "
	"probably a buggy MTA has been used\n") );
	m_free( afx->buffer );
	afx->buffer = NULL;
	}
	else if( control == IOBUFCTRL_DESC )
	(char*)buf = "armor_filter";
	return rc;
	}


	/****************
	* create a radix64 encoded string.
	*/
	char *
	make_radix64_string( const byte *data, size_t len )
	{
	char buffer, p;

	buffer = p = m_alloc( (len+2)/3*4 + 1 );
	for( ; len >= 3 ; len -= 3, data += 3 ) {
	*p++ = bintoasc[(data[0] >> 2) & 077];
	*p++ = bintoasc[(((data[0] <<4)&060)\|((data[1] >> 4)&017))&077];
	*p++ = bintoasc[(((data[1]<<2)&074)\|((data[2]>>6)&03))&077];
	*p++ = bintoasc[data[2]&077];
	}
	if( len == 2 ) {
	*p++ = bintoasc[(data[0] >> 2) & 077];
	*p++ = bintoasc[(((data[0] <<4)&060)\|((data[1] >> 4)&017))&077];
	*p++ = bintoasc[((data[1]<<2)&074)];
	}
	else if( len == 1 ) {
	*p++ = bintoasc[(data[0] >> 2) & 077];
	*p++ = bintoasc[(data[0] <<4)&060];
	}
	*p = 0;
	return buffer;
	}


	/***********************************************
	* 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 = m_alloc_clear (sizeof *x);
	return x;
	}

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

	/*
	* Get the next character from the ascii armor taken from the IOBUF
	* 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 ) {
	log_error(_("invalid radix64 character %02x skipped\n"), c2);
	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 ) {
	log_info (_("CRC error; %06lx - %06lx\n"),
	(ulong)x->crc, (ulong)x->mycrc);
	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;
	}

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