--- /dev/null
+/* -*- c-file-style: "python"; indent-tabs-mode: nil; -*-
+
+ Python wrapper for Samba tdb pack/unpack functions
+ Copyright (C) Martin Pool 2002, 2003
+
+
+ NOTE PYTHON STYLE GUIDE
+ http://www.python.org/peps/pep-0007.html
+
+
+ This program 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.
+
+ This program 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "Python.h"
+
+/* This symbol is used in both config.h and Python.h which causes an
+ annoying compiler warning. */
+
+#ifdef HAVE_FSTAT
+#undef HAVE_FSTAT
+#endif
+
+/* This module is supposed to be standalone, however for portability
+ it would be good to use the FUNCTION_MACRO preprocessor define. */
+
+#include "include/config.h"
+
+#ifdef HAVE_FUNCTION_MACRO
+#define FUNCTION_MACRO (__FUNCTION__)
+#else
+#define FUNCTION_MACRO (__FILE__)
+#endif
+
+static PyObject * pytdbpack_number(char ch, PyObject *val_iter, PyObject *packed_list);
+static PyObject * pytdbpack_str(char ch,
+ PyObject *val_iter, PyObject *packed_list,
+ const char *encoding);
+static PyObject * pytdbpack_buffer(PyObject *val_iter, PyObject *packed_list);
+
+static PyObject *pytdbunpack_item(char, char **pbuf, int *plen, PyObject *);
+
+static PyObject *pytdbpack_data(const char *format_str,
+ PyObject *val_seq,
+ PyObject *val_list);
+
+static PyObject *
+pytdbunpack_string(char **pbuf, int *plen, const char *encoding);
+
+static void pack_le_uint32(unsigned long val_long, unsigned char *pbuf);
+
+
+static PyObject *pytdbpack_bad_type(char ch,
+ const char *expected,
+ PyObject *val_obj);
+
+static const char * pytdbpack_docstring =
+"Convert between Python values and Samba binary encodings.\n"
+"\n"
+"This module is conceptually similar to the standard 'struct' module, but it\n"
+"uses both a different binary format and a different description string.\n"
+"\n"
+"Samba's encoding is based on that used inside DCE-RPC and SMB: a\n"
+"little-endian, unpadded, non-self-describing binary format. It is intended\n"
+"that these functions be as similar as possible to the routines in Samba's\n"
+"tdb/tdbutil module, with appropriate adjustments for Python datatypes.\n"
+"\n"
+"Python strings are used to specify the format of data to be packed or\n"
+"unpacked.\n"
+"\n"
+"String encodings are implied by the database format: they may be either DOS\n"
+"codepage (currently hardcoded to 850), or Unix codepage (currently hardcoded\n"
+"to be the same as the default Python encoding).\n"
+"\n"
+"tdbpack format strings:\n"
+"\n"
+" 'f': NUL-terminated string in codepage iso8859-1\n"
+" \n"
+" 'P': same as 'f'\n"
+"\n"
+" 'F': NUL-terminated string in iso-8859-1\n"
+"\n"
+" 'd': 4 byte little-endian unsigned number\n"
+"\n"
+" 'w': 2 byte little-endian unsigned number\n"
+"\n"
+" 'P': \"Pointer\" value -- in the subset of DCERPC used by Samba, this is\n"
+" really just an \"exists\" or \"does not exist\" flag. The boolean\n"
+" value of the Python object is used.\n"
+" \n"
+" 'B': 4-byte LE length, followed by that many bytes of binary data.\n"
+" Corresponds to a Python integer giving the length, followed by a byte\n"
+" string of the appropriate length.\n"
+"\n"
+" '$': Special flag indicating that the preceding format code should be\n"
+" repeated while data remains. This is only supported for unpacking.\n"
+"\n"
+" Every code corresponds to a single Python object, except 'B' which\n"
+" corresponds to two values (length and contents), and '$', which produces\n"
+" however many make sense.\n";
+
+static char const pytdbpack_doc[] =
+"pack(format, values) -> buffer\n"
+"Pack Python objects into Samba binary format according to format string.\n"
+"\n"
+"arguments:\n"
+" format -- string of tdbpack format characters\n"
+" values -- sequence of value objects corresponding 1:1 to format characters\n"
+"\n"
+"returns:\n"
+" buffer -- string containing packed data\n"
+"\n"
+"raises:\n"
+" IndexError -- if there are too few values for the format\n"
+" ValueError -- if any of the format characters is illegal\n"
+" TypeError -- if the format is not a string, or values is not a sequence,\n"
+" or any of the values is of the wrong type for the corresponding\n"
+" format character\n"
+"\n"
+"notes:\n"
+" For historical reasons, it is not an error to pass more values than are consumed\n"
+" by the format.\n";
+
+
+static char const pytdbunpack_doc[] =
+"unpack(format, buffer) -> (values, rest)\n"
+"Unpack Samba binary data according to format string.\n"
+"\n"
+"arguments:\n"
+" format -- string of tdbpack characters\n"
+" buffer -- string of packed binary data\n"
+"\n"
+"returns:\n"
+" 2-tuple of:\n"
+" values -- sequence of values corresponding 1:1 to format characters\n"
+" rest -- string containing data that was not decoded, or '' if the\n"
+" whole string was consumed\n"
+"\n"
+"raises:\n"
+" IndexError -- if there is insufficient data in the buffer for the\n"
+" format (or if the data is corrupt and contains a variable-length\n"
+" field extending past the end)\n"
+" ValueError -- if any of the format characters is illegal\n"
+"\n"
+"notes:\n"
+" Because unconsumed data is returned, you can feed it back in to the\n"
+" unpacker to extract further fields. Alternatively, if you wish to modify\n"
+" some fields near the start of the data, you may be able to save time by\n"
+" only unpacking and repacking the necessary part.\n";
+
+
+const char *pytdb_dos_encoding = "cp850";
+
+/* NULL, meaning that the Samba default encoding *must* be the same as the
+ Python default encoding. */
+const char *pytdb_unix_encoding = NULL;
+
+
+/*
+ * Pack objects to bytes.
+ *
+ * All objects are first individually encoded onto a list, and then the list
+ * of strings is concatenated. This is faster than concatenating strings,
+ * and reasonably simple to code.
+ */
+static PyObject *
+pytdbpack(PyObject *self,
+ PyObject *args)
+{
+ char *format_str;
+ PyObject *val_seq, *val_iter = NULL,
+ *packed_list = NULL, *packed_str = NULL,
+ *empty_str = NULL;
+
+ /* TODO: Test passing wrong types or too many arguments */
+ if (!PyArg_ParseTuple(args, "sO", &format_str, &val_seq))
+ return NULL;
+
+ if (!(val_iter = PyObject_GetIter(val_seq)))
+ goto out;
+
+ /* Create list to hold strings until we're done, then join them all. */
+ if (!(packed_list = PyList_New(0)))
+ goto out;
+
+ if (!pytdbpack_data(format_str, val_iter, packed_list))
+ goto out;
+
+ /* this function is not officially documented but it works */
+ if (!(empty_str = PyString_InternFromString("")))
+ goto out;
+
+ packed_str = _PyString_Join(empty_str, packed_list);
+
+ out:
+ Py_XDECREF(empty_str);
+ Py_XDECREF(val_iter);
+ Py_XDECREF(packed_list);
+
+ return packed_str;
+}
+
+
+/*
+ Pack data according to FORMAT_STR from the elements of VAL_SEQ into
+ PACKED_BUF.
+
+ The string has already been checked out, so we know that VAL_SEQ is large
+ enough to hold the packed data, and that there are enough value items.
+ (However, their types may not have been thoroughly checked yet.)
+
+ In addition, val_seq is a Python Fast sequence.
+
+ Returns NULL for error (with exception set), or None.
+*/
+PyObject *
+pytdbpack_data(const char *format_str,
+ PyObject *val_iter,
+ PyObject *packed_list)
+{
+ int format_i, val_i = 0;
+
+ for (format_i = 0, val_i = 0; format_str[format_i]; format_i++) {
+ char ch = format_str[format_i];
+
+ switch (ch) {
+ /* dispatch to the appropriate packer for this type,
+ which should pull things off the iterator, and
+ append them to the packed_list */
+ case 'w':
+ case 'd':
+ case 'p':
+ if (!(packed_list = pytdbpack_number(ch, val_iter, packed_list)))
+ return NULL;
+ break;
+
+ case 'f':
+ case 'P':
+ if (!(packed_list = pytdbpack_str(ch, val_iter, packed_list, pytdb_unix_encoding)))
+ return NULL;
+ break;
+
+ case 'B':
+ if (!(packed_list = pytdbpack_buffer(val_iter, packed_list)))
+ return NULL;
+ break;
+
+ default:
+ PyErr_Format(PyExc_ValueError,
+ "%s: format character '%c' is not supported",
+ FUNCTION_MACRO, ch);
+ return NULL;
+ }
+ }
+
+ return packed_list;
+}
+
+
+static PyObject *
+pytdbpack_number(char ch, PyObject *val_iter, PyObject *packed_list)
+{
+ unsigned long val_long;
+ PyObject *val_obj = NULL, *long_obj = NULL, *result_obj = NULL;
+ PyObject *new_list = NULL;
+ unsigned char pack_buf[4];
+
+ if (!(val_obj = PyIter_Next(val_iter)))
+ goto out;
+
+ if (!(long_obj = PyNumber_Long(val_obj))) {
+ pytdbpack_bad_type(ch, "Number", val_obj);
+ goto out;
+ }
+
+ val_long = PyLong_AsUnsignedLong(long_obj);
+ pack_le_uint32(val_long, pack_buf);
+
+ /* pack as 32-bit; if just packing a 'w' 16-bit word then only take
+ the first two bytes. */
+
+ if (!(result_obj = PyString_FromStringAndSize(pack_buf, ch == 'w' ? 2 : 4)))
+ goto out;
+
+ if (PyList_Append(packed_list, result_obj) != -1)
+ new_list = packed_list;
+
+ out:
+ Py_XDECREF(val_obj);
+ Py_XDECREF(long_obj);
+ Py_XDECREF(result_obj);
+
+ return new_list;
+}
+
+
+/*
+ * Take one string from the iterator val_iter, convert it to 8-bit, and return
+ * it.
+ *
+ * If the input is neither a string nor Unicode, an exception is raised.
+ *
+ * If the input is Unicode, then it is converted to the appropriate encoding.
+ *
+ * If the input is a String, and encoding is not null, then it is converted to
+ * Unicode using the default decoding method, and then converted to the
+ * encoding. If the encoding is NULL, then the string is written out as-is --
+ * this is used when the default Python encoding is the same as the Samba
+ * encoding.
+ *
+ * I hope this approach avoids being too fragile w.r.t. being passed either
+ * Unicode or String objects.
+ */
+static PyObject *
+pytdbpack_str(char ch,
+ PyObject *val_iter, PyObject *packed_list, const char *encoding)
+{
+ PyObject *val_obj = NULL;
+ PyObject *unicode_obj = NULL;
+ PyObject *coded_str = NULL;
+ PyObject *nul_str = NULL;
+ PyObject *new_list = NULL;
+
+ if (!(val_obj = PyIter_Next(val_iter)))
+ goto out;
+
+ if (PyUnicode_Check(val_obj)) {
+ if (!(coded_str = PyUnicode_AsEncodedString(val_obj, encoding, NULL)))
+ goto out;
+ }
+ else if (PyString_Check(val_obj) && !encoding) {
+ /* For efficiency, we assume that the Python interpreter has
+ the same default string encoding as Samba's native string
+ encoding. On the PSA, both are always 8859-1. */
+ coded_str = val_obj;
+ Py_INCREF(coded_str);
+ }
+ else if (PyString_Check(val_obj)) {
+ /* String, but needs to be converted */
+ if (!(unicode_obj = PyString_AsDecodedObject(val_obj, NULL, NULL)))
+ goto out;
+ if (!(coded_str = PyUnicode_AsEncodedString(unicode_obj, encoding, NULL)))
+ goto out;
+ }
+ else {
+ pytdbpack_bad_type(ch, "String or Unicode", val_obj);
+ goto out;
+ }
+
+ if (!nul_str)
+ /* this is constant and often-used; hold it forever */
+ if (!(nul_str = PyString_FromStringAndSize("", 1)))
+ goto out;
+
+ if ((PyList_Append(packed_list, coded_str) != -1)
+ && (PyList_Append(packed_list, nul_str) != -1))
+ new_list = packed_list;
+
+ out:
+ Py_XDECREF(val_obj);
+ Py_XDECREF(unicode_obj);
+ Py_XDECREF(coded_str);
+
+ return new_list;
+}
+
+
+/*
+ * Pack (LENGTH, BUFFER) pair onto the list.
+ *
+ * The buffer must already be a String, not Unicode, because it contains 8-bit
+ * untranslated data. In some cases it will actually be UTF_16_LE data.
+ */
+static PyObject *
+pytdbpack_buffer(PyObject *val_iter, PyObject *packed_list)
+{
+ PyObject *val_obj;
+ PyObject *new_list = NULL;
+
+ /* pull off integer and stick onto list */
+ if (!(packed_list = pytdbpack_number('d', val_iter, packed_list)))
+ return NULL;
+
+ /* this assumes that the string is the right length; the old code did
+ the same. */
+ if (!(val_obj = PyIter_Next(val_iter)))
+ return NULL;
+
+ if (!PyString_Check(val_obj)) {
+ pytdbpack_bad_type('B', "String", val_obj);
+ goto out;
+ }
+
+ if (PyList_Append(packed_list, val_obj) != -1)
+ new_list = packed_list;
+
+ out:
+ Py_XDECREF(val_obj);
+ return new_list;
+}
+
+
+static PyObject *pytdbpack_bad_type(char ch,
+ const char *expected,
+ PyObject *val_obj)
+{
+ PyObject *r = PyObject_Repr(val_obj);
+ if (!r)
+ return NULL;
+ PyErr_Format(PyExc_TypeError,
+ "tdbpack: format '%c' requires %s, not %s",
+ ch, expected, PyString_AS_STRING(r));
+ Py_DECREF(r);
+ return val_obj;
+}
+
+
+/*
+ XXX: glib and Samba have quicker macro for doing the endianness conversions,
+ but I don't know of one in plain libc, and it's probably not a big deal. I
+ realize this is kind of dumb because we'll almost always be on x86, but
+ being safe is important.
+*/
+static void pack_le_uint32(unsigned long val_long, unsigned char *pbuf)
+{
+ pbuf[0] = val_long & 0xff;
+ pbuf[1] = (val_long >> 8) & 0xff;
+ pbuf[2] = (val_long >> 16) & 0xff;
+ pbuf[3] = (val_long >> 24) & 0xff;
+}
+
+
+#if 0 /* not used */
+static void pack_bytes(long len, const char *from,
+ unsigned char **pbuf)
+{
+ memcpy(*pbuf, from, len);
+ (*pbuf) += len;
+}
+#endif
+
+
+static PyObject *
+pytdbunpack(PyObject *self,
+ PyObject *args)
+{
+ char *format_str, *packed_str, *ppacked;
+ PyObject *val_list = NULL, *ret_tuple = NULL;
+ PyObject *rest_string = NULL;
+ int format_len, packed_len;
+ char last_format = '#'; /* invalid */
+ int i;
+
+ /* get arguments */
+ if (!PyArg_ParseTuple(args, "ss#", &format_str, &packed_str, &packed_len))
+ return NULL;
+
+ format_len = strlen(format_str);
+
+ /* Allocate list to hold results. Initially empty, and we append
+ results as we go along. */
+ val_list = PyList_New(0);
+ if (!val_list)
+ goto failed;
+ ret_tuple = PyTuple_New(2);
+ if (!ret_tuple)
+ goto failed;
+
+ /* For every object, unpack. */
+ for (ppacked = packed_str, i = 0; i < format_len && format_str[i] != '$'; i++) {
+ last_format = format_str[i];
+ /* packed_len is reduced in place */
+ if (!pytdbunpack_item(format_str[i], &ppacked, &packed_len, val_list))
+ goto failed;
+ }
+
+ /* If the last character was '$', keep going until out of space */
+ if (format_str[i] == '$') {
+ if (i == 0) {
+ PyErr_Format(PyExc_ValueError,
+ "%s: '$' may not be first character in format",
+ FUNCTION_MACRO);
+ return NULL;
+ }
+ while (packed_len > 0)
+ if (!pytdbunpack_item(last_format, &ppacked, &packed_len, val_list))
+ goto failed;
+ }
+
+ /* save leftovers for next time */
+ rest_string = PyString_FromStringAndSize(ppacked, packed_len);
+ if (!rest_string)
+ goto failed;
+
+ /* return (values, rest) tuple; give up references to them */
+ PyTuple_SET_ITEM(ret_tuple, 0, val_list);
+ val_list = NULL;
+ PyTuple_SET_ITEM(ret_tuple, 1, rest_string);
+ val_list = NULL;
+ return ret_tuple;
+
+ failed:
+ /* handle failure: deallocate anything. XDECREF forms handle NULL
+ pointers for objects that haven't been allocated yet. */
+ Py_XDECREF(val_list);
+ Py_XDECREF(ret_tuple);
+ Py_XDECREF(rest_string);
+ return NULL;
+}
+
+
+static void
+pytdbunpack_err_too_short(void)
+{
+ PyErr_Format(PyExc_IndexError,
+ "%s: data too short for unpack format", FUNCTION_MACRO);
+}
+
+
+static PyObject *
+pytdbunpack_uint32(char **pbuf, int *plen)
+{
+ unsigned long v;
+ unsigned char *b;
+
+ if (*plen < 4) {
+ pytdbunpack_err_too_short();
+ return NULL;
+ }
+
+ b = *pbuf;
+ v = b[0] | b[1]<<8 | b[2]<<16 | b[3]<<24;
+
+ (*pbuf) += 4;
+ (*plen) -= 4;
+
+ return PyLong_FromUnsignedLong(v);
+}
+
+
+static PyObject *pytdbunpack_int16(char **pbuf, int *plen)
+{
+ long v;
+ unsigned char *b;
+
+ if (*plen < 2) {
+ pytdbunpack_err_too_short();
+ return NULL;
+ }
+
+ b = *pbuf;
+ v = b[0] | b[1]<<8;
+
+ (*pbuf) += 2;
+ (*plen) -= 2;
+
+ return PyInt_FromLong(v);
+}
+
+
+static PyObject *
+pytdbunpack_string(char **pbuf, int *plen, const char *encoding)
+{
+ int len;
+ char *nul_ptr, *start;
+
+ start = *pbuf;
+
+ nul_ptr = memchr(start, '\0', *plen);
+ if (!nul_ptr) {
+ pytdbunpack_err_too_short();
+ return NULL;
+ }
+
+ len = nul_ptr - start;
+
+ *pbuf += len + 1; /* skip \0 */
+ *plen -= len + 1;
+
+ return PyString_Decode(start, len, encoding, NULL);
+}
+
+
+static PyObject *
+pytdbunpack_buffer(char **pbuf, int *plen, PyObject *val_list)
+{
+ /* first get 32-bit len */
+ long slen;
+ unsigned char *b;
+ unsigned char *start;
+ PyObject *str_obj = NULL, *len_obj = NULL;
+
+ if (*plen < 4) {
+ pytdbunpack_err_too_short();
+ return NULL;
+ }
+
+ b = *pbuf;
+ slen = b[0] | b[1]<<8 | b[2]<<16 | b[3]<<24;
+
+ if (slen < 0) { /* surely you jest */
+ PyErr_Format(PyExc_ValueError,
+ "%s: buffer seems to have negative length", FUNCTION_MACRO);
+ return NULL;
+ }
+
+ (*pbuf) += 4;
+ (*plen) -= 4;
+ start = *pbuf;
+
+ if (*plen < slen) {
+ PyErr_Format(PyExc_IndexError,
+ "%s: not enough data to unpack buffer: "
+ "need %d bytes, have %d", FUNCTION_MACRO,
+ (int) slen, *plen);
+ return NULL;
+ }
+
+ (*pbuf) += slen;
+ (*plen) -= slen;
+
+ if (!(len_obj = PyInt_FromLong(slen)))
+ goto failed;
+
+ if (PyList_Append(val_list, len_obj) == -1)
+ goto failed;
+
+ if (!(str_obj = PyString_FromStringAndSize(start, slen)))
+ goto failed;
+
+ if (PyList_Append(val_list, str_obj) == -1)
+ goto failed;
+
+ Py_DECREF(len_obj);
+ Py_DECREF(str_obj);
+
+ return val_list;
+
+ failed:
+ Py_XDECREF(len_obj); /* handles NULL */
+ Py_XDECREF(str_obj);
+ return NULL;
+}
+
+
+/* Unpack a single field from packed data, according to format character CH.
+ Remaining data is at *PBUF, of *PLEN.
+
+ *PBUF is advanced, and *PLEN reduced to reflect the amount of data that has
+ been consumed.
+
+ Returns a reference to None, or NULL for failure.
+*/
+static PyObject *pytdbunpack_item(char ch,
+ char **pbuf,
+ int *plen,
+ PyObject *val_list)
+{
+ PyObject *unpacked;
+
+ if (ch == 'w') { /* 16-bit int */
+ unpacked = pytdbunpack_int16(pbuf, plen);
+ }
+ else if (ch == 'd' || ch == 'p') { /* 32-bit int */
+ /* pointers can just come through as integers */
+ unpacked = pytdbunpack_uint32(pbuf, plen);
+ }
+ else if (ch == 'f' || ch == 'P') { /* nul-term string */
+ unpacked = pytdbunpack_string(pbuf, plen, pytdb_unix_encoding);
+ }
+ else if (ch == 'B') { /* length, buffer */
+ return pytdbunpack_buffer(pbuf, plen, val_list);
+ }
+ else {
+ PyErr_Format(PyExc_ValueError,
+ "%s: format character '%c' is not supported",
+ FUNCTION_MACRO, ch);
+
+ return NULL;
+ }
+
+ /* otherwise OK */
+ if (!unpacked)
+ return NULL;
+
+ if (PyList_Append(val_list, unpacked) == -1)
+ val_list = NULL;
+
+ /* PyList_Append takes a new reference to the inserted object.
+ Therefore, we no longer need the original reference. */
+ Py_DECREF(unpacked);
+
+ return val_list;
+}
+
+
+
+
+
+
+static PyMethodDef pytdbpack_methods[] = {
+ { "pack", pytdbpack, METH_VARARGS, (char *) pytdbpack_doc },
+ { "unpack", pytdbunpack, METH_VARARGS, (char *) pytdbunpack_doc },
+};
+
+DL_EXPORT(void)
+inittdbpack(void)
+{
+ Py_InitModule3("tdbpack", pytdbpack_methods,
+ (char *) pytdbpack_docstring);
+}
projects / samba / blobdiff