/* armor.c - Armor filters
 * Copyright (C) 1998-2012 Free Software Foundation, Inc.
 *
 * Author: Timo Schulz
 *
 * This file is part of OpenCDK.
 *
 * The OpenCDK library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <base64.h>

#include "opencdk.h"
#include "main.h"
#include "filters.h"

#ifdef _WIN32
#define LF "\r\n"
#define ALTLF "\n"
#else
#define LF "\n"
#define ALTLF "\r\n"
#endif

#define CRCINIT 0xB704CE

static const u32 crc_table[] = {
	0x000000, 0x864CFB, 0x8AD50D, 0x0C99F6, 0x93E6E1, 0x15AA1A,
	0x1933EC, 0x9F7F17, 0xA18139, 0x27CDC2, 0x2B5434, 0xAD18CF,
	0x3267D8, 0xB42B23, 0xB8B2D5, 0x3EFE2E, 0xC54E89, 0x430272,
	0x4F9B84, 0xC9D77F, 0x56A868, 0xD0E493, 0xDC7D65, 0x5A319E,
	0x64CFB0, 0xE2834B, 0xEE1ABD, 0x685646, 0xF72951, 0x7165AA,
	0x7DFC5C, 0xFBB0A7, 0x0CD1E9, 0x8A9D12, 0x8604E4, 0x00481F,
	0x9F3708, 0x197BF3, 0x15E205, 0x93AEFE, 0xAD50D0, 0x2B1C2B,
	0x2785DD, 0xA1C926, 0x3EB631, 0xB8FACA, 0xB4633C, 0x322FC7,
	0xC99F60, 0x4FD39B, 0x434A6D, 0xC50696, 0x5A7981, 0xDC357A,
	0xD0AC8C, 0x56E077, 0x681E59, 0xEE52A2, 0xE2CB54, 0x6487AF,
	0xFBF8B8, 0x7DB443, 0x712DB5, 0xF7614E, 0x19A3D2, 0x9FEF29,
	0x9376DF, 0x153A24, 0x8A4533, 0x0C09C8, 0x00903E, 0x86DCC5,
	0xB822EB, 0x3E6E10, 0x32F7E6, 0xB4BB1D, 0x2BC40A, 0xAD88F1,
	0xA11107, 0x275DFC, 0xDCED5B, 0x5AA1A0, 0x563856, 0xD074AD,
	0x4F0BBA, 0xC94741, 0xC5DEB7, 0x43924C, 0x7D6C62, 0xFB2099,
	0xF7B96F, 0x71F594, 0xEE8A83, 0x68C678, 0x645F8E, 0xE21375,
	0x15723B, 0x933EC0, 0x9FA736, 0x19EBCD, 0x8694DA, 0x00D821,
	0x0C41D7, 0x8A0D2C, 0xB4F302, 0x32BFF9, 0x3E260F, 0xB86AF4,
	0x2715E3, 0xA15918, 0xADC0EE, 0x2B8C15, 0xD03CB2, 0x567049,
	0x5AE9BF, 0xDCA544, 0x43DA53, 0xC596A8, 0xC90F5E, 0x4F43A5,
	0x71BD8B, 0xF7F170, 0xFB6886, 0x7D247D, 0xE25B6A, 0x641791,
	0x688E67, 0xEEC29C, 0x3347A4, 0xB50B5F, 0xB992A9, 0x3FDE52,
	0xA0A145, 0x26EDBE, 0x2A7448, 0xAC38B3, 0x92C69D, 0x148A66,
	0x181390, 0x9E5F6B, 0x01207C, 0x876C87, 0x8BF571, 0x0DB98A,
	0xF6092D, 0x7045D6, 0x7CDC20, 0xFA90DB, 0x65EFCC, 0xE3A337,
	0xEF3AC1, 0x69763A, 0x578814, 0xD1C4EF, 0xDD5D19, 0x5B11E2,
	0xC46EF5, 0x42220E, 0x4EBBF8, 0xC8F703, 0x3F964D, 0xB9DAB6,
	0xB54340, 0x330FBB, 0xAC70AC, 0x2A3C57, 0x26A5A1, 0xA0E95A,
	0x9E1774, 0x185B8F, 0x14C279, 0x928E82, 0x0DF195, 0x8BBD6E,
	0x872498, 0x016863, 0xFAD8C4, 0x7C943F, 0x700DC9, 0xF64132,
	0x693E25, 0xEF72DE, 0xE3EB28, 0x65A7D3, 0x5B59FD, 0xDD1506,
	0xD18CF0, 0x57C00B, 0xC8BF1C, 0x4EF3E7, 0x426A11, 0xC426EA,
	0x2AE476, 0xACA88D, 0xA0317B, 0x267D80,	0xB90297, 0x3F4E6C,
	0x33D79A, 0xB59B61, 0x8B654F, 0x0D29B4, 0x01B042, 0x87FCB9,
	0x1883AE, 0x9ECF55, 0x9256A3, 0x141A58, 0xEFAAFF, 0x69E604,
	0x657FF2, 0xE33309, 0x7C4C1E, 0xFA00E5, 0xF69913, 0x70D5E8,
	0x4E2BC6, 0xC8673D, 0xC4FECB, 0x42B230, 0xDDCD27, 0x5B81DC,
	0x57182A, 0xD154D1, 0x26359F, 0xA07964, 0xACE092, 0x2AAC69,
	0xB5D37E, 0x339F85, 0x3F0673, 0xB94A88, 0x87B4A6, 0x01F85D,
	0x0D61AB, 0x8B2D50, 0x145247, 0x921EBC, 0x9E874A, 0x18CBB1,
	0xE37B16, 0x6537ED, 0x69AE1B, 0xEFE2E0, 0x709DF7, 0xF6D10C,
	0xFA48FA, 0x7C0401, 0x42FA2F, 0xC4B6D4, 0xC82F22, 0x4E63D9,
	0xD11CCE, 0x575035, 0x5BC9C3, 0xDD8538
};

static const char *armor_begin[] = {
	"BEGIN PGP MESSAGE",
	"BEGIN PGP PUBLIC KEY BLOCK",
	"BEGIN PGP PRIVATE KEY BLOCK",
	"BEGIN PGP SIGNATURE",
	NULL
};

static const char *armor_end[] = {
	"END PGP MESSAGE",
	"END PGP PUBLIC KEY BLOCK",
	"END PGP PRIVATE KEY BLOCK",
	"END PGP SIGNATURE",
	NULL
};

static const char *valid_headers[] = {
	"Comment",
	"Version",
	"MessageID",
	"Hash",
	"Charset",
	NULL
};

static char b64chars[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static u32 update_crc(u32 crc, const byte * buf, size_t buflen)
{
	unsigned int j;

	if (!crc)
		crc = CRCINIT;

	for (j = 0; j < buflen; j++)
		crc =
		    (crc << 8) ^ crc_table[0xff & ((crc >> 16) ^ buf[j])];
	crc &= 0xffffff;
	return crc;
}


static cdk_error_t armor_encode(void *data, FILE * in, FILE * out)
{
	armor_filter_t *afx = data;
	struct stat statbuf;
	char crcbuf[5], buf[128], raw[49];
	byte crcbuf2[3];
	size_t nread = 0;
	const char *lf;

	if (!afx) {
		gnutls_assert();
		return CDK_Inv_Value;
	}
	if (afx->idx < 0 || afx->idx >= (int) DIM(armor_begin) ||
	    afx->idx2 < 0 || afx->idx2 >= (int) DIM(armor_end)) {
		gnutls_assert();
		return CDK_Inv_Value;
	}

	_gnutls_buffers_log("armor filter: encode\n");

	memset(crcbuf, 0, sizeof(crcbuf));

	lf = afx->le ? afx->le : LF;
	fprintf(out, "-----%s-----%s", armor_begin[afx->idx], lf);
	fprintf(out, "Version: OpenPrivacy " PACKAGE_VERSION "%s", lf);
	if (afx->hdrlines)
		fwrite(afx->hdrlines, 1, strlen(afx->hdrlines), out);
	fprintf(out, "%s", lf);

	if (fstat(fileno(in), &statbuf)) {
		gnutls_assert();
		return CDK_General_Error;
	}

	while (!feof(in)) {
		nread = fread(raw, 1, DIM(raw) - 1, in);
		if (!nread)
			break;
		if (ferror(in)) {
			gnutls_assert();
			return CDK_File_Error;
		}
		afx->crc = update_crc(afx->crc, (byte *) raw, nread);
		base64_encode(raw, nread, buf, DIM(buf) - 1);
		fprintf(out, "%s%s", buf, lf);
	}

	crcbuf2[0] = afx->crc >> 16;
	crcbuf2[1] = afx->crc >> 8;
	crcbuf2[2] = afx->crc;
	crcbuf[0] = b64chars[crcbuf2[0] >> 2];
	crcbuf[1] =
	    b64chars[((crcbuf2[0] << 4) & 0x30) | (crcbuf2[1] >> 4)];
	crcbuf[2] =
	    b64chars[((crcbuf2[1] << 2) & 0x3c) | (crcbuf2[2] >> 6)];
	crcbuf[3] = b64chars[crcbuf2[2] & 0x3f];
	fprintf(out, "=%s%s", crcbuf, lf);
	fprintf(out, "-----%s-----%s", armor_end[afx->idx2], lf);

	return 0;
}

static int search_header(const char *buf, const char **array)
{
	const char *s;
	int i;

	if (strlen(buf) < 5 || strncmp(buf, "-----", 5)) {
		return -1;
	}
	for (i = 0; (s = array[i]); i++) {
		if (!strncmp(s, buf + 5, strlen(s)))
			return i;
	}
	return -1;
}

static cdk_error_t armor_decode(void *data, FILE * in, FILE * out)
{
	armor_filter_t *afx = data;
	const char *s;
	char buf[127];
	byte raw[128], crcbuf[4];
	u32 crc2 = 0;
	ssize_t nread = 0;
	int i, pgp_data = 0;
	cdk_error_t rc = 0;
	int len;
	size_t raw_size, crcbuf_size;

	if (!afx) {
		gnutls_assert();
		return CDK_Inv_Value;
	}

	_gnutls_buffers_log("armor filter: decode\n");

	fseek(in, 0, SEEK_SET);
	/* Search the begin of the message */
	while (!feof(in) && !pgp_data) {
		s = fgets(buf, DIM(buf) - 1, in);
		if (!s)
			break;
		afx->idx = search_header(buf, armor_begin);
		if (afx->idx >= 0)
			pgp_data = 1;
	}

	if (feof(in) || !pgp_data) {
		return CDK_Armor_Error;	/* no data found */
	}

	/* Parse header until the empty line is reached */
	while (!feof(in)) {
		s = fgets(buf, DIM(buf) - 1, in);
		if (!s)
			return CDK_EOF;
		if (strcmp(s, LF) == 0 || strcmp(s, ALTLF) == 0) {
			rc = 0;
			break;	/* empty line */
		}
		/* From RFC2440: OpenPGP should consider improperly formatted Armor
		   Headers to be corruption of the ASCII Armor. A colon and a single
		   space separate the key and value. */
		if (!strstr(buf, ": ")) {
			gnutls_assert();
			return CDK_Armor_Error;
		}
		rc = CDK_General_Error;
		for (i = 0; (s = valid_headers[i]); i++) {
			if (!strncmp(s, buf, strlen(s)))
				rc = 0;
		}
		if (rc) {
			/* From RFC2440: Unknown keys should be reported to the user,
			   but OpenPGP should continue to process the message. */
			_cdk_log_info("unknown header: `%s'\n", buf);
			rc = 0;
		}
	}

	/* Read the data body */
	while (!feof(in)) {
		s = fgets(buf, DIM(buf) - 1, in);
		if (!s)
			break;

		len = strlen(buf);

		if (len > 0 && buf[len - 1] == '\n') {
			len--;
			buf[len] = '\0';
		}
		if (len > 0 && buf[len - 1] == '\r') {
			len--;
			buf[len] = '\0';
		}
		if (buf[0] == '=' && strlen(s) == 5) {	/* CRC */
			memset(crcbuf, 0, sizeof(crcbuf));
			crcbuf_size = sizeof(crcbuf);
			base64_decode(buf + 1, len - 1, (char *) crcbuf,
				      &crcbuf_size);
			crc2 =
			    (crcbuf[0] << 16) | (crcbuf[1] << 8) |
			    crcbuf[2];
			break;	/* stop here */
		} else {
			raw_size = sizeof(raw);
			nread =
			    base64_decode(buf, len, (char *) raw,
					  &raw_size);
			if (nread == 0)
				break;
			afx->crc = update_crc(afx->crc, raw, raw_size);
			fwrite(raw, 1, raw_size, out);
		}
	}

	/* Search the tail of the message */
	s = fgets(buf, DIM(buf) - 1, in);
	if (s) {
		int buf_len = strlen(buf);
		if (buf[buf_len - 1] == '\n') {
			buf_len--;
			buf[buf_len] = '\0';
		}
		if (buf[buf_len - 1] == '\r') {
			buf_len--;
			buf[buf_len] = '\0';
		}
		rc = CDK_General_Error;
		afx->idx2 = search_header(buf, armor_end);
		if (afx->idx2 >= 0)
			rc = 0;
	}

	/* This catches error when no tail was found or the header is
	   different then the tail line. */
	if (rc || afx->idx != afx->idx2)
		rc = CDK_Armor_Error;

	afx->crc_okay = (afx->crc == crc2) ? 1 : 0;
	if (!afx->crc_okay && !rc) {
		_gnutls_buffers_log("file crc=%08X afx_crc=%08X\n",
				    (unsigned int) crc2,
				    (unsigned int) afx->crc);
		rc = CDK_Armor_CRC_Error;
	}

	return rc;
}

int _cdk_filter_armor(void *data, int ctl, FILE * in, FILE * out)
{
	if (ctl == STREAMCTL_READ)
		return armor_decode(data, in, out);
	else if (ctl == STREAMCTL_WRITE)
		return armor_encode(data, in, out);
	else if (ctl == STREAMCTL_FREE) {
		armor_filter_t *afx = data;
		if (afx) {
			_gnutls_buffers_log("free armor filter\n");
			afx->idx = afx->idx2 = 0;
			afx->crc = afx->crc_okay = 0;
			return 0;
		}
	}

	gnutls_assert();
	return CDK_Inv_Mode;
}


/**
 * cdk_armor_encode_buffer:
 * @inbuf: the raw input buffer
 * @inlen: raw buffer len
 * @outbuf: the destination buffer for the base64 output
 * @outlen: destination buffer len
 * @nwritten: actual length of the base64 data
 * @type: the base64 file type.
 * 
 * Encode the given buffer into base64 format. The base64
 * string will be null terminated but the null will
 * not be contained in the size.
 **/
cdk_error_t
cdk_armor_encode_buffer(const byte * inbuf, size_t inlen,
			char *outbuf, size_t outlen,
			size_t * nwritten, int type)
{
	const char *head, *tail, *le;
	char tempbuf[48];
	char tempout[128];
	size_t pos, off, len, rest;

	if (!inbuf || !nwritten) {
		gnutls_assert();
		return CDK_Inv_Value;
	}
	if (type > CDK_ARMOR_SIGNATURE) {
		gnutls_assert();
		return CDK_Inv_Mode;
	}

	head = armor_begin[type];
	tail = armor_end[type];
	le = LF;
	pos =
	    strlen(head) + 10 + 2 + 2 + strlen(tail) + 10 + 2 + 5 + 2 + 1;
	/* The output data is 4/3 times larger, plus a line end for each line. */
	pos += (4 * inlen / 3) + 2 * (4 * inlen / 3 / 64) + 1;

	if (outbuf && outlen < pos) {
		gnutls_assert();
		*nwritten = pos;
		return CDK_Too_Short;
	}

	/* Only return the size of the output. */
	if (!outbuf) {
		*nwritten = pos;
		return 0;
	}

	memset(outbuf, 0, outlen);
	memcpy(outbuf, "-----", 5);
	pos = 5;
	memcpy(outbuf + pos, head, strlen(head));
	pos += strlen(head);
	memcpy(outbuf + pos, "-----", 5);
	pos += 5;
	memcpy(outbuf + pos, le, strlen(le));
	pos += strlen(le);
	memcpy(outbuf + pos, le, strlen(le));
	pos += strlen(le);
	rest = inlen;
	for (off = 0; off < inlen;) {
		if (rest > 48) {
			memcpy(tempbuf, inbuf + off, 48);
			off += 48;
			len = 48;
		} else {
			memcpy(tempbuf, inbuf + off, rest);
			off += rest;
			len = rest;
		}
		rest -= len;
		base64_encode(tempbuf, len, tempout, DIM(tempout) - 1);
		memcpy(outbuf + pos, tempout, strlen(tempout));
		pos += strlen(tempout);
		memcpy(outbuf + pos, le, strlen(le));
		pos += strlen(le);
	}

	memcpy(outbuf + pos, "-----", 5);
	pos += 5;
	memcpy(outbuf + pos, tail, strlen(tail));
	pos += strlen(tail);
	memcpy(outbuf + pos, "-----", 5);
	pos += 5;
	memcpy(outbuf + pos, le, strlen(le));
	pos += strlen(le);
	outbuf[pos] = 0;
	*nwritten = pos - 1;
	return 0;
}
