/*

** Routines to represent binary data in ASCII and vice-versa

**

** This module currently supports the following encodings:

** uuencode:

**     	each line encodes 45 bytes (except possibly the last)

**	First char encodes (binary) length, rest data

**	each char encodes 6 bits, as follows:

**	binary: 01234567 abcdefgh ijklmnop

**	ascii:  012345 67abcd efghij klmnop

**	ASCII encoding method is "excess-space": 000000 is encoded as ' ', etc.

**	short binary data is zero-extended (so the bits are always in the

**	right place), this does *not* reflect in the length.

** base64:

**      Line breaks are insignificant, but lines are at most 76 chars

**      each char encodes 6 bits, in similar order as uucode/hqx. Encoding

**      is done via a table.

**      Short binary data is filled (in ASCII) with '='.

** hqx:

**	File starts with introductory text, real data starts and ends

**	with colons.

**	Data consists of three similar parts: info, datafork, resourcefork.

**	Each part is protected (at the end) with a 16-bit crc

**	The binary data is run-length encoded, and then ascii-fied:

**	binary: 01234567 abcdefgh ijklmnop

**	ascii:  012345 67abcd efghij klmnop

**	ASCII encoding is table-driven, see the code.

**	Short binary data results in the runt ascii-byte being output with

**	the bits in the right place.

**

** While I was reading dozens of programs that encode or decode the formats

** here (documentation? hihi:-) I have formulated Jansen's Observation:

**

**	Programs that encode binary data in ASCII are written in

**	such a style that they are as unreadable as possible. Devices used

**	include unnecessary global variables, burying important tables

**	in unrelated sourcefiles, putting functions in include files,

**	using seemingly-descriptive variable names for different purposes,

**	calls to empty subroutines and a host of others.

**

** I have attempted to break with this tradition, but I guess that that

** does make the performance sub-optimal. Oh well, too bad...

**

** Jack Jansen, CWI, July 1995.

**

** Added support for quoted-printable encoding, based on rfc 1521 et al

** quoted-printable encoding specifies that non printable characters (anything

** below 32 and above 126) be encoded as =XX where XX is the hexadecimal value

** of the character.  It also specifies some other behavior to enable 8bit data

** in a mail message with little difficulty (maximum line sizes, protecting

** some cases of whitespace, etc).

**

** Brandon Long, September 2001.

*/

#define PY_SSIZE_T_CLEAN

#include "Python.h"

#ifdef USE_ZLIB_CRC32

#include "zlib.h"

#endif

static PyObject *Error;

static PyObject *Incomplete;

/*

** hqx lookup table, ascii->binary.

*/

#define RUNCHAR 0x90

#define DONE 0x7F

#define SKIP 0x7E

#define FAIL 0x7D

static unsigned char table_a2b_hqx[256] = {

/*       ^@    ^A    ^B    ^C    ^D    ^E    ^F    ^G   */

/* 0*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

/*       \b    \t    \n    ^K    ^L    \r    ^N    ^O   */

/* 1*/	FAIL, FAIL, SKIP, FAIL, FAIL, SKIP, FAIL, FAIL,

/*       ^P    ^Q    ^R    ^S    ^T    ^U    ^V    ^W   */

/* 2*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

/*       ^X    ^Y    ^Z    ^[    ^\    ^]    ^^    ^_   */

/* 3*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

/*              !     "     #     $     %     &     '   */

/* 4*/	FAIL, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,

/*        (     )     *     +     ,     -     .     /   */

/* 5*/	0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, FAIL, FAIL,

/*        0     1     2     3     4     5     6     7   */

/* 6*/	0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13, FAIL,

/*        8     9     :     ;     <     =     >     ?   */

/* 7*/	0x14, 0x15, DONE, FAIL, FAIL, FAIL, FAIL, FAIL,

/*        @     A     B     C     D     E     F     G   */

/* 8*/	0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,

/*        H     I     J     K     L     M     N     O   */

/* 9*/	0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, FAIL,

/*        P     Q     R     S     T     U     V     W   */

/*10*/	0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, FAIL,

/*        X     Y     Z     [     \     ]     ^     _   */

/*11*/	0x2C, 0x2D, 0x2E, 0x2F, FAIL, FAIL, FAIL, FAIL,

/*        `     a     b     c     d     e     f     g   */

/*12*/	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, FAIL,

/*        h     i     j     k     l     m     n     o   */

/*13*/	0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, FAIL, FAIL,

/*        p     q     r     s     t     u     v     w   */

/*14*/	0x3D, 0x3E, 0x3F, FAIL, FAIL, FAIL, FAIL, FAIL,

/*        x     y     z     {     |     }     ~    ^?   */

/*15*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

/*16*/	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

	FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL, FAIL,

};

static unsigned char table_b2a_hqx[] =

"!\"#$%&'()*+,-012345689@ABCDEFGHIJKLMNPQRSTUVXYZ[`abcdefhijklmpqr";

static char table_a2b_base64[] = {

	-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,

	-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,

	-1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,

	52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1, 0,-1,-1, /* Note PAD->0 */

	-1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,

	15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,

	-1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,

	41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1

};

#define BASE64_PAD '='

/* Max binary chunk size; limited only by available memory */

#define BASE64_MAXBIN (PY_SSIZE_T_MAX/2 - sizeof(PyStringObject) - 3)

static unsigned char table_b2a_base64[] =

"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static unsigned short crctab_hqx[256] = {

	0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,

	0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,

	0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,

	0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,

	0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,

	0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,

	0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,

	0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,

	0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,

	0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,

	0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,

	0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,

	0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,

	0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,

	0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,

	0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,

	0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,

	0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,

	0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,

	0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,

	0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,

	0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,

	0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,

	0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,

	0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,

	0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,

	0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,

	0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,

	0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,

	0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,

	0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,

	0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,

};

PyDoc_STRVAR(doc_a2b_uu, "(ascii) -> bin. Decode a line of uuencoded data");

static PyObject *

binascii_a2b_uu(PyObject *self, PyObject *args)

{

	unsigned char *ascii_data, *bin_data;

	int leftbits = 0;

	unsigned char this_ch;

	unsigned int leftchar = 0;

	PyObject *rv;

	Py_ssize_t ascii_len, bin_len;

	if ( !PyArg_ParseTuple(args, "t#:a2b_uu", &ascii_data, &ascii_len) )

		return NULL;

	assert(ascii_len >= 0);

	/* First byte: binary data length (in bytes) */

	bin_len = (*ascii_data++ - ' ') & 077;

	ascii_len--;

	/* Allocate the buffer */

	if ( (rv=PyString_FromStringAndSize(NULL, bin_len)) == NULL )

		return NULL;

	bin_data = (unsigned char *)PyString_AsString(rv);

	for( ; bin_len > 0 ; ascii_len--, ascii_data++ ) {

		/* XXX is it really best to add NULs if there's no more data */

		this_ch = (ascii_len > 0) ? *ascii_data : 0;

		if ( this_ch == '\n' || this_ch == '\r' || ascii_len <= 0) {

			/*

			** Whitespace. Assume some spaces got eaten at

			** end-of-line. (We check this later)

			*/

			this_ch = 0;

	        } else {

			/* Check the character for legality

			** The 64 in stead of the expected 63 is because

			** there are a few uuencodes out there that use

			** '`' as zero instead of space.

			*/

			if ( this_ch < ' ' || this_ch > (' ' + 64)) {

				PyErr_SetString(Error, "Illegal char");

				Py_DECREF(rv);

				return NULL;

			}

			this_ch = (this_ch - ' ') & 077;

		}

		/*

		** Shift it in on the low end, and see if there's

		** a byte ready for output.

		*/

		leftchar = (leftchar << 6) | (this_ch);

		leftbits += 6;

		if ( leftbits >= 8 ) {

			leftbits -= 8;

			*bin_data++ = (leftchar >> leftbits) & 0xff;

			leftchar &= ((1 << leftbits) - 1);

			bin_len--;

		}

	}

	/*

	** Finally, check that if there's anything left on the line

	** that it's whitespace only.

	*/

	while( ascii_len-- > 0 ) {

		this_ch = *ascii_data++;

		/* Extra '`' may be written as padding in some cases */

		if ( this_ch != ' ' && this_ch != ' '+64 &&

		     this_ch != '\n' && this_ch != '\r' ) {

			PyErr_SetString(Error, "Trailing garbage");

			Py_DECREF(rv);

			return NULL;

		}

	}

	return rv;

}

PyDoc_STRVAR(doc_b2a_uu, "(bin) -> ascii. Uuencode line of data");

static PyObject *

binascii_b2a_uu(PyObject *self, PyObject *args)

{

	unsigned char *ascii_data, *bin_data;

	int leftbits = 0;

	unsigned char this_ch;

	unsigned int leftchar = 0;

	PyObject *rv;

	Py_ssize_t bin_len;

	if ( !PyArg_ParseTuple(args, "s#:b2a_uu", &bin_data, &bin_len) )

		return NULL;

	if ( bin_len > 45 ) {

		/* The 45 is a limit that appears in all uuencode's */

		PyErr_SetString(Error, "At most 45 bytes at once");

		return NULL;

	}

	/* We're lazy and allocate to much (fixed up later) */

	if ( (rv=PyString_FromStringAndSize(NULL, bin_len*2+2)) == NULL )

		return NULL;

	ascii_data = (unsigned char *)PyString_AsString(rv);

	/* Store the length */

	*ascii_data++ = ' ' + (bin_len & 077);

	for( ; bin_len > 0 || leftbits != 0 ; bin_len--, bin_data++ ) {

		/* Shift the data (or padding) into our buffer */

		if ( bin_len > 0 )	/* Data */

			leftchar = (leftchar << 8) | *bin_data;

		else			/* Padding */

			leftchar <<= 8;

		leftbits += 8;

		/* See if there are 6-bit groups ready */

		while ( leftbits >= 6 ) {

			this_ch = (leftchar >> (leftbits-6)) & 0x3f;

			leftbits -= 6;

			*ascii_data++ = this_ch + ' ';

		}

	}

	*ascii_data++ = '\n';	/* Append a courtesy newline */

	_PyString_Resize(&rv, (ascii_data -

			       (unsigned char *)PyString_AsString(rv)));

	return rv;

}

static int

binascii_find_valid(unsigned char *s, Py_ssize_t slen, int num)

{

	/* Finds & returns the (num+1)th

	** valid character for base64, or -1 if none.

	*/

	int ret = -1;

	unsigned char c, b64val;

	while ((slen > 0) && (ret == -1)) {

		c = *s;

		b64val = table_a2b_base64[c & 0x7f];

		if ( ((c <= 0x7f) && (b64val != (unsigned char)-1)) ) {

			if (num == 0)

				ret = *s;

			num--;

		}

		s++;

		slen--;

	}

	return ret;

}

PyDoc_STRVAR(doc_a2b_base64, "(ascii) -> bin. Decode a line of base64 data");

static PyObject *

binascii_a2b_base64(PyObject *self, PyObject *args)

{

	unsigned char *ascii_data, *bin_data;

	int leftbits = 0;

	unsigned char this_ch;

	unsigned int leftchar = 0;

	PyObject *rv;

	Py_ssize_t ascii_len, bin_len;

	int quad_pos = 0;

	if ( !PyArg_ParseTuple(args, "t#:a2b_base64", &ascii_data, &ascii_len) )

		return NULL;

	assert(ascii_len >= 0);

	if (ascii_len > PY_SSIZE_T_MAX - 3)

		return PyErr_NoMemory();

	bin_len = ((ascii_len+3)/4)*3; /* Upper bound, corrected later */

	/* Allocate the buffer */

	if ( (rv=PyString_FromStringAndSize(NULL, bin_len)) == NULL )

		return NULL;

	bin_data = (unsigned char *)PyString_AsString(rv);

	bin_len = 0;

	for( ; ascii_len > 0; ascii_len--, ascii_data++) {

		this_ch = *ascii_data;

		if (this_ch > 0x7f ||

		    this_ch == '\r' || this_ch == '\n' || this_ch == ' ')

			continue;

		/* Check for pad sequences and ignore

		** the invalid ones.

		*/

		if (this_ch == BASE64_PAD) {

			if ( (quad_pos < 2) ||

			     ((quad_pos == 2) &&

			      (binascii_find_valid(ascii_data, ascii_len, 1)

			       != BASE64_PAD)) )

			{

				continue;

			}

			else {

				/* A pad sequence means no more input.

				** We've already interpreted the data

				** from the quad at this point.

				*/

				leftbits = 0;

				break;

			}

		}

		this_ch = table_a2b_base64[*ascii_data];

		if ( this_ch == (unsigned char) -1 )

			continue;

		/*

		** Shift it in on the low end, and see if there's

		** a byte ready for output.

		*/

		quad_pos = (quad_pos + 1) & 0x03;

		leftchar = (leftchar << 6) | (this_ch);

		leftbits += 6;

		if ( leftbits >= 8 ) {

			leftbits -= 8;

			*bin_data++ = (leftchar >> leftbits) & 0xff;

			bin_len++;

			leftchar &= ((1 << leftbits) - 1);

		}

 	}

	if (leftbits != 0) {

		PyErr_SetString(Error, "Incorrect padding");

		Py_DECREF(rv);

		return NULL;

	}

	/* And set string size correctly. If the result string is empty

	** (because the input was all invalid) return the shared empty

	** string instead; _PyString_Resize() won't do this for us.

	*/

	if (bin_len > 0)

		_PyString_Resize(&rv, bin_len);

	else {

		Py_DECREF(rv);

		rv = PyString_FromString("");

	}

	return rv;

}

PyDoc_STRVAR(doc_b2a_base64, "(bin) -> ascii. Base64-code line of data");

static PyObject *

binascii_b2a_base64(PyObject *self, PyObject *args)

{

	unsigned char *ascii_data, *bin_data;

	int leftbits = 0;

	unsigned char this_ch;

	unsigned int leftchar = 0;

	PyObject *rv;

	Py_ssize_t bin_len;

	if ( !PyArg_ParseTuple(args, "s#:b2a_base64", &bin_data, &bin_len) )

		return NULL;

	assert(bin_len >= 0);

	if ( bin_len > BASE64_MAXBIN ) {

		PyErr_SetString(Error, "Too much data for base64 line");

		return NULL;

	}

	/* We're lazy and allocate too much (fixed up later).

	   "+3" leaves room for up to two pad characters and a trailing

	   newline.  Note that 'b' gets encoded as 'Yg==\n' (1 in, 5 out). */

	if ( (rv=PyString_FromStringAndSize(NULL, bin_len*2 + 3)) == NULL )

		return NULL;

	ascii_data = (unsigned char *)PyString_AsString(rv);

	for( ; bin_len > 0 ; bin_len--, bin_data++ ) {

		/* Shift the data into our buffer */

		leftchar = (leftchar << 8) | *bin_data;

		leftbits += 8;

		/* See if there are 6-bit groups ready */

		while ( leftbits >= 6 ) {

			this_ch = (leftchar >> (leftbits-6)) & 0x3f;

			leftbits -= 6;

			*ascii_data++ = table_b2a_base64[this_ch];

		}

	}

	if ( leftbits == 2 ) {

		*ascii_data++ = table_b2a_base64[(leftchar&3) << 4];

		*ascii_data++ = BASE64_PAD;

		*ascii_data++ = BASE64_PAD;

	} else if ( leftbits == 4 ) {

		*ascii_data++ = table_b2a_base64[(leftchar&0xf) << 2];

		*ascii_data++ = BASE64_PAD;

	}

	*ascii_data++ = '\n';	/* Append a courtesy newline */

	_PyString_Resize(&rv, (ascii_data -

			       (unsigned char *)PyString_AsString(rv)));

	return rv;

}

PyDoc_STRVAR(doc_a2b_hqx, "ascii -> bin, done. Decode .hqx coding");

static PyObject *

binascii_a2b_hqx(PyObject *self, PyObject *args)

{

	unsigned char *ascii_data, *bin_data;

	int leftbits = 0;

	unsigned char this_ch;

	unsigned int leftchar = 0;

	PyObject *rv;

	Py_ssize_t len;

	int done = 0;

	if ( !PyArg_ParseTuple(args, "t#:a2b_hqx", &ascii_data, &len) )

		return NULL;

	assert(len >= 0);

	if (len > PY_SSIZE_T_MAX - 2)

		return PyErr_NoMemory();

	/* Allocate a string that is too big (fixed later) 

	   Add two to the initial length to prevent interning which

	   would preclude subsequent resizing.  */

	if ( (rv=PyString_FromStringAndSize(NULL, len+2)) == NULL )

		return NULL;

	bin_data = (unsigned char *)PyString_AsString(rv);

	for( ; len > 0 ; len--, ascii_data++ ) {

		/* Get the byte and look it up */

		this_ch = table_a2b_hqx[*ascii_data];

		if ( this_ch == SKIP )

			continue;

		if ( this_ch == FAIL ) {

			PyErr_SetString(Error, "Illegal char");

			Py_DECREF(rv);

			return NULL;