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cpython/Modules/_hashopenssl.c
Gregory P. Smith 13b55291ac hashlib has two new constant attributes: algorithms_guaranteed and 
algorithms_avaiable that respectively list the names of hash algorithms
guaranteed to exist in all Python implementations and the names of hash
algorithms available in the current process.

Renames the attribute new in 3.2a0 'algorithms' to 'algorithms_guaranteed'.
2010-09-06 08:30:23 +00:00

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/* Module that wraps all OpenSSL hash algorithms */
/*
* Copyright (C) 2005-2010 Gregory P. Smith (greg@krypto.org)
* Licensed to PSF under a Contributor Agreement.
*
* Derived from a skeleton of shamodule.c containing work performed by:
*
* Andrew Kuchling (amk@amk.ca)
* Greg Stein (gstein@lyra.org)
*
*/
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include "structmember.h"
#include "hashlib.h"
#ifdef WITH_THREAD
#include "pythread.h"
#define ENTER_HASHLIB(obj) \
if ((obj)->lock) { \
if (!PyThread_acquire_lock((obj)->lock, 0)) { \
Py_BEGIN_ALLOW_THREADS \
PyThread_acquire_lock((obj)->lock, 1); \
Py_END_ALLOW_THREADS \
} \
}
#define LEAVE_HASHLIB(obj) \
if ((obj)->lock) { \
PyThread_release_lock((obj)->lock); \
}
#else
#define ENTER_HASHLIB(obj)
#define LEAVE_HASHLIB(obj)
#endif
/* EVP is the preferred interface to hashing in OpenSSL */
#include <openssl/evp.h>
/* We use the object interface to discover what hashes OpenSSL supports. */
#include <openssl/objects.h>
#define MUNCH_SIZE INT_MAX
/* TODO(gps): We should probably make this a module or EVPobject attribute
* to allow the user to optimize based on the platform they're using. */
#define HASHLIB_GIL_MINSIZE 2048
#ifndef HASH_OBJ_CONSTRUCTOR
#define HASH_OBJ_CONSTRUCTOR 0
#endif
/* Minimum OpenSSL version needed to support sha224 and higher. */
#if defined(OPENSSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x00908000)
#define _OPENSSL_SUPPORTS_SHA2
#endif
typedef struct {
PyObject_HEAD
PyObject *name; /* name of this hash algorithm */
EVP_MD_CTX ctx; /* OpenSSL message digest context */
#ifdef WITH_THREAD
PyThread_type_lock lock; /* OpenSSL context lock */
#endif
} EVPobject;
static PyTypeObject EVPtype;
#define DEFINE_CONSTS_FOR_NEW(Name) \
static PyObject *CONST_ ## Name ## _name_obj; \
static EVP_MD_CTX CONST_new_ ## Name ## _ctx; \
static EVP_MD_CTX *CONST_new_ ## Name ## _ctx_p = NULL;
DEFINE_CONSTS_FOR_NEW(md5)
DEFINE_CONSTS_FOR_NEW(sha1)
#ifdef _OPENSSL_SUPPORTS_SHA2
DEFINE_CONSTS_FOR_NEW(sha224)
DEFINE_CONSTS_FOR_NEW(sha256)
DEFINE_CONSTS_FOR_NEW(sha384)
DEFINE_CONSTS_FOR_NEW(sha512)
#endif
static EVPobject *
newEVPobject(PyObject *name)
{
EVPobject *retval = (EVPobject *)PyObject_New(EVPobject, &EVPtype);
/* save the name for .name to return */
if (retval != NULL) {
Py_INCREF(name);
retval->name = name;
#ifdef WITH_THREAD
retval->lock = NULL;
#endif
}
return retval;
}
static void
EVP_hash(EVPobject *self, const void *vp, Py_ssize_t len)
{
unsigned int process;
const unsigned char *cp = (const unsigned char *)vp;
while (0 < len) {
if (len > (Py_ssize_t)MUNCH_SIZE)
process = MUNCH_SIZE;
else
process = Py_SAFE_DOWNCAST(len, Py_ssize_t, unsigned int);
EVP_DigestUpdate(&self->ctx, (const void*)cp, process);
len -= process;
cp += process;
}
}
/* Internal methods for a hash object */
static void
EVP_dealloc(EVPobject *self)
{
#ifdef WITH_THREAD
if (self->lock != NULL)
PyThread_free_lock(self->lock);
#endif
EVP_MD_CTX_cleanup(&self->ctx);
Py_XDECREF(self->name);
PyObject_Del(self);
}
static void locked_EVP_MD_CTX_copy(EVP_MD_CTX *new_ctx_p, EVPobject *self)
{
ENTER_HASHLIB(self);
EVP_MD_CTX_copy(new_ctx_p, &self->ctx);
LEAVE_HASHLIB(self);
}
/* External methods for a hash object */
PyDoc_STRVAR(EVP_copy__doc__, "Return a copy of the hash object.");
static PyObject *
EVP_copy(EVPobject *self, PyObject *unused)
{
EVPobject *newobj;
if ( (newobj = newEVPobject(self->name))==NULL)
return NULL;
locked_EVP_MD_CTX_copy(&newobj->ctx, self);
return (PyObject *)newobj;
}
PyDoc_STRVAR(EVP_digest__doc__,
"Return the digest value as a string of binary data.");
static PyObject *
EVP_digest(EVPobject *self, PyObject *unused)
{
unsigned char digest[EVP_MAX_MD_SIZE];
EVP_MD_CTX temp_ctx;
PyObject *retval;
unsigned int digest_size;
locked_EVP_MD_CTX_copy(&temp_ctx, self);
digest_size = EVP_MD_CTX_size(&temp_ctx);
EVP_DigestFinal(&temp_ctx, digest, NULL);
retval = PyBytes_FromStringAndSize((const char *)digest, digest_size);
EVP_MD_CTX_cleanup(&temp_ctx);
return retval;
}
PyDoc_STRVAR(EVP_hexdigest__doc__,
"Return the digest value as a string of hexadecimal digits.");
static PyObject *
EVP_hexdigest(EVPobject *self, PyObject *unused)
{
unsigned char digest[EVP_MAX_MD_SIZE];
EVP_MD_CTX temp_ctx;
PyObject *retval;
char *hex_digest;
unsigned int i, j, digest_size;
/* Get the raw (binary) digest value */
locked_EVP_MD_CTX_copy(&temp_ctx, self);
digest_size = EVP_MD_CTX_size(&temp_ctx);
EVP_DigestFinal(&temp_ctx, digest, NULL);
EVP_MD_CTX_cleanup(&temp_ctx);
/* Allocate a new buffer */
hex_digest = PyMem_Malloc(digest_size * 2 + 1);
if (!hex_digest)
return PyErr_NoMemory();
/* Make hex version of the digest */
for(i=j=0; i<digest_size; i++) {
char c;
c = (digest[i] >> 4) & 0xf;
c = (c>9) ? c+'a'-10 : c + '0';
hex_digest[j++] = c;
c = (digest[i] & 0xf);
c = (c>9) ? c+'a'-10 : c + '0';
hex_digest[j++] = c;
}
retval = PyUnicode_FromStringAndSize(hex_digest, digest_size * 2);
PyMem_Free(hex_digest);
return retval;
}
PyDoc_STRVAR(EVP_update__doc__,
"Update this hash object's state with the provided string.");
static PyObject *
EVP_update(EVPobject *self, PyObject *args)
{
PyObject *obj;
Py_buffer view;
if (!PyArg_ParseTuple(args, "O:update", &obj))
return NULL;
GET_BUFFER_VIEW_OR_ERROUT(obj, &view);
#ifdef WITH_THREAD
if (self->lock == NULL && view.len >= HASHLIB_GIL_MINSIZE) {
self->lock = PyThread_allocate_lock();
/* fail? lock = NULL and we fail over to non-threaded code. */
}
if (self->lock != NULL) {
Py_BEGIN_ALLOW_THREADS
PyThread_acquire_lock(self->lock, 1);
EVP_hash(self, view.buf, view.len);
PyThread_release_lock(self->lock);
Py_END_ALLOW_THREADS
} else {
EVP_hash(self, view.buf, view.len);
}
#else
EVP_hash(self, view.buf, view.len);
#endif
PyBuffer_Release(&view);
Py_RETURN_NONE;
}
static PyMethodDef EVP_methods[] = {
{"update", (PyCFunction)EVP_update, METH_VARARGS, EVP_update__doc__},
{"digest", (PyCFunction)EVP_digest, METH_NOARGS, EVP_digest__doc__},
{"hexdigest", (PyCFunction)EVP_hexdigest, METH_NOARGS, EVP_hexdigest__doc__},
{"copy", (PyCFunction)EVP_copy, METH_NOARGS, EVP_copy__doc__},
{NULL, NULL} /* sentinel */
};
static PyObject *
EVP_get_block_size(EVPobject *self, void *closure)
{
long block_size;
block_size = EVP_MD_CTX_block_size(&self->ctx);
return PyLong_FromLong(block_size);
}
static PyObject *
EVP_get_digest_size(EVPobject *self, void *closure)
{
long size;
size = EVP_MD_CTX_size(&self->ctx);
return PyLong_FromLong(size);
}
static PyMemberDef EVP_members[] = {
{"name", T_OBJECT, offsetof(EVPobject, name), READONLY, PyDoc_STR("algorithm name.")},
{NULL} /* Sentinel */
};
static PyGetSetDef EVP_getseters[] = {
{"digest_size",
(getter)EVP_get_digest_size, NULL,
NULL,
NULL},
{"block_size",
(getter)EVP_get_block_size, NULL,
NULL,
NULL},
{NULL} /* Sentinel */
};
static PyObject *
EVP_repr(EVPobject *self)
{
return PyUnicode_FromFormat("<%U HASH object @ %p>", self->name, self);
}
#if HASH_OBJ_CONSTRUCTOR
static int
EVP_tp_init(EVPobject *self, PyObject *args, PyObject *kwds)
{
static char *kwlist[] = {"name", "string", NULL};
PyObject *name_obj = NULL;
PyObject *data_obj = NULL;
Py_buffer view;
char *nameStr;
const EVP_MD *digest;
if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|O:HASH", kwlist,
&name_obj, &data_obj)) {
return -1;
}
if (data_obj)
GET_BUFFER_VIEW_OR_ERROUT(data_obj, &view);
if (!PyArg_Parse(name_obj, "s", &nameStr)) {
PyErr_SetString(PyExc_TypeError, "name must be a string");
if (data_obj)
PyBuffer_Release(&view);
return -1;
}
digest = EVP_get_digestbyname(nameStr);
if (!digest) {
PyErr_SetString(PyExc_ValueError, "unknown hash function");
if (data_obj)
PyBuffer_Release(&view);
return -1;
}
EVP_DigestInit(&self->ctx, digest);
self->name = name_obj;
Py_INCREF(self->name);
if (data_obj) {
if (view.len >= HASHLIB_GIL_MINSIZE) {
Py_BEGIN_ALLOW_THREADS
EVP_hash(self, view.buf, view.len);
Py_END_ALLOW_THREADS
} else {
EVP_hash(self, view.buf, view.len);
}
PyBuffer_Release(&view);
}
return 0;
}
#endif
PyDoc_STRVAR(hashtype_doc,
"A hash represents the object used to calculate a checksum of a\n\
string of information.\n\
\n\
Methods:\n\
\n\
update() -- updates the current digest with an additional string\n\
digest() -- return the current digest value\n\
hexdigest() -- return the current digest as a string of hexadecimal digits\n\
copy() -- return a copy of the current hash object\n\
\n\
Attributes:\n\
\n\
name -- the hash algorithm being used by this object\n\
digest_size -- number of bytes in this hashes output\n");
static PyTypeObject EVPtype = {
PyVarObject_HEAD_INIT(NULL, 0)
"_hashlib.HASH", /*tp_name*/
sizeof(EVPobject), /*tp_basicsize*/
0, /*tp_itemsize*/
/* methods */
(destructor)EVP_dealloc, /*tp_dealloc*/
0, /*tp_print*/
0, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_reserved*/
(reprfunc)EVP_repr, /*tp_repr*/
0, /*tp_as_number*/
0, /*tp_as_sequence*/
0, /*tp_as_mapping*/
0, /*tp_hash*/
0, /*tp_call*/
0, /*tp_str*/
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
hashtype_doc, /*tp_doc*/
0, /*tp_traverse*/
0, /*tp_clear*/
0, /*tp_richcompare*/
0, /*tp_weaklistoffset*/
0, /*tp_iter*/
0, /*tp_iternext*/
EVP_methods, /* tp_methods */
EVP_members, /* tp_members */
EVP_getseters, /* tp_getset */
#if 1
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
#endif
#if HASH_OBJ_CONSTRUCTOR
(initproc)EVP_tp_init, /* tp_init */
#endif
};
static PyObject *
EVPnew(PyObject *name_obj,
const EVP_MD *digest, const EVP_MD_CTX *initial_ctx,
const unsigned char *cp, Py_ssize_t len)
{
EVPobject *self;
if (!digest && !initial_ctx) {
PyErr_SetString(PyExc_ValueError, "unsupported hash type");
return NULL;
}
if ((self = newEVPobject(name_obj)) == NULL)
return NULL;
if (initial_ctx) {
EVP_MD_CTX_copy(&self->ctx, initial_ctx);
} else {
EVP_DigestInit(&self->ctx, digest);
}
if (cp && len) {
if (len >= HASHLIB_GIL_MINSIZE) {
Py_BEGIN_ALLOW_THREADS
EVP_hash(self, cp, len);
Py_END_ALLOW_THREADS
} else {
EVP_hash(self, cp, len);
}
}
return (PyObject *)self;
}
/* The module-level function: new() */
PyDoc_STRVAR(EVP_new__doc__,
"Return a new hash object using the named algorithm.\n\
An optional string argument may be provided and will be\n\
automatically hashed.\n\
\n\
The MD5 and SHA1 algorithms are always supported.\n");
static PyObject *
EVP_new(PyObject *self, PyObject *args, PyObject *kwdict)
{
static char *kwlist[] = {"name", "string", NULL};
PyObject *name_obj = NULL;
PyObject *data_obj = NULL;
Py_buffer view = { 0 };
PyObject *ret_obj;
char *name;
const EVP_MD *digest;
if (!PyArg_ParseTupleAndKeywords(args, kwdict, "O|O:new", kwlist,
&name_obj, &data_obj)) {
return NULL;
}
if (!PyArg_Parse(name_obj, "s", &name)) {
PyErr_SetString(PyExc_TypeError, "name must be a string");
return NULL;
}
if (data_obj)
GET_BUFFER_VIEW_OR_ERROUT(data_obj, &view);
digest = EVP_get_digestbyname(name);
ret_obj = EVPnew(name_obj, digest, NULL, (unsigned char*)view.buf, view.len);
if (data_obj)
PyBuffer_Release(&view);
return ret_obj;
}
/* State for our callback function so that it can accumulate a result. */
typedef struct _internal_name_mapper_state {
PyObject *set;
int error;
} _InternalNameMapperState;
/* A callback function to pass to OpenSSL's OBJ_NAME_do_all(...) */
static void
_openssl_hash_name_mapper(const OBJ_NAME *openssl_obj_name, void *arg)
{
_InternalNameMapperState *state = (_InternalNameMapperState *)arg;
PyObject *py_name;
assert(state != NULL);
if (openssl_obj_name == NULL)
return;
/* Ignore aliased names, they pollute the list and OpenSSL appears to
* have a its own definition of alias as the resulting list still
* contains duplicate and alternate names for several algorithms. */
if (openssl_obj_name->alias)
return;
py_name = PyUnicode_FromString(openssl_obj_name->name);
if (py_name == NULL) {
state->error = 1;
} else {
if (PySet_Add(state->set, py_name) != 0) {
Py_DECREF(py_name);
state->error = 1;
}
}
}
/* Ask OpenSSL for a list of supported ciphers, filling in a Python set. */
static PyObject*
generate_hash_name_list(void)
{
_InternalNameMapperState state;
state.set = PyFrozenSet_New(NULL);
if (state.set == NULL)
return NULL;
state.error = 0;
OBJ_NAME_do_all(OBJ_NAME_TYPE_MD_METH, &_openssl_hash_name_mapper, &state);
if (state.error) {
Py_DECREF(state.set);
return NULL;
}
return state.set;
}
/*
* This macro generates constructor function definitions for specific
* hash algorithms. These constructors are much faster than calling
* the generic one passing it a python string and are noticably
* faster than calling a python new() wrapper. Thats important for
* code that wants to make hashes of a bunch of small strings.
*/
#define GEN_CONSTRUCTOR(NAME) \
static PyObject * \
EVP_new_ ## NAME (PyObject *self, PyObject *args) \
{ \
PyObject *data_obj = NULL; \
Py_buffer view = { 0 }; \
PyObject *ret_obj; \
\
if (!PyArg_ParseTuple(args, "|O:" #NAME , &data_obj)) { \
return NULL; \
} \
\
if (data_obj) \
GET_BUFFER_VIEW_OR_ERROUT(data_obj, &view); \
\
ret_obj = EVPnew( \
CONST_ ## NAME ## _name_obj, \
NULL, \
CONST_new_ ## NAME ## _ctx_p, \
(unsigned char*)view.buf, \
view.len); \
\
if (data_obj) \
PyBuffer_Release(&view); \
return ret_obj; \
}
/* a PyMethodDef structure for the constructor */
#define CONSTRUCTOR_METH_DEF(NAME) \
{"openssl_" #NAME, (PyCFunction)EVP_new_ ## NAME, METH_VARARGS, \
PyDoc_STR("Returns a " #NAME \
" hash object; optionally initialized with a string") \
}
/* used in the init function to setup a constructor */
#define INIT_CONSTRUCTOR_CONSTANTS(NAME) do { \
CONST_ ## NAME ## _name_obj = PyUnicode_FromString(#NAME); \
if (EVP_get_digestbyname(#NAME)) { \
CONST_new_ ## NAME ## _ctx_p = &CONST_new_ ## NAME ## _ctx; \
EVP_DigestInit(CONST_new_ ## NAME ## _ctx_p, EVP_get_digestbyname(#NAME)); \
} \
} while (0);
GEN_CONSTRUCTOR(md5)
GEN_CONSTRUCTOR(sha1)
#ifdef _OPENSSL_SUPPORTS_SHA2
GEN_CONSTRUCTOR(sha224)
GEN_CONSTRUCTOR(sha256)
GEN_CONSTRUCTOR(sha384)
GEN_CONSTRUCTOR(sha512)
#endif
/* List of functions exported by this module */
static struct PyMethodDef EVP_functions[] = {
{"new", (PyCFunction)EVP_new, METH_VARARGS|METH_KEYWORDS, EVP_new__doc__},
CONSTRUCTOR_METH_DEF(md5),
CONSTRUCTOR_METH_DEF(sha1),
#ifdef _OPENSSL_SUPPORTS_SHA2
CONSTRUCTOR_METH_DEF(sha224),
CONSTRUCTOR_METH_DEF(sha256),
CONSTRUCTOR_METH_DEF(sha384),
CONSTRUCTOR_METH_DEF(sha512),
#endif
{NULL, NULL} /* Sentinel */
};
/* Initialize this module. */
static struct PyModuleDef _hashlibmodule = {
PyModuleDef_HEAD_INIT,
"_hashlib",
NULL,
-1,
EVP_functions,
NULL,
NULL,
NULL,
NULL
};
PyMODINIT_FUNC
PyInit__hashlib(void)
{
PyObject *m, *openssl_md_meth_names;
OpenSSL_add_all_digests();
/* TODO build EVP_functions openssl_* entries dynamically based
* on what hashes are supported rather than listing many
* but having some be unsupported. Only init appropriate
* constants. */
Py_TYPE(&EVPtype) = &PyType_Type;
if (PyType_Ready(&EVPtype) < 0)
return NULL;
m = PyModule_Create(&_hashlibmodule);
if (m == NULL)
return NULL;
openssl_md_meth_names = generate_hash_name_list();
if (openssl_md_meth_names == NULL) {
Py_DECREF(m);
return NULL;
}
if (PyModule_AddObject(m, "openssl_md_meth_names", openssl_md_meth_names)) {
Py_DECREF(m);
return NULL;
}
#if HASH_OBJ_CONSTRUCTOR
Py_INCREF(&EVPtype);
PyModule_AddObject(m, "HASH", (PyObject *)&EVPtype);
#endif
/* these constants are used by the convenience constructors */
INIT_CONSTRUCTOR_CONSTANTS(md5);
INIT_CONSTRUCTOR_CONSTANTS(sha1);
#ifdef _OPENSSL_SUPPORTS_SHA2
INIT_CONSTRUCTOR_CONSTANTS(sha224);
INIT_CONSTRUCTOR_CONSTANTS(sha256);
INIT_CONSTRUCTOR_CONSTANTS(sha384);
INIT_CONSTRUCTOR_CONSTANTS(sha512);
#endif
return m;
}
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