D7815: sha1dc: initial implementation of Python extension
durin42 (Augie Fackler)
phabricator at mercurial-scm.org
Mon Jan 13 17:48:44 EST 2020
durin42 marked an inline comment as done.
durin42 updated this revision to Diff 19188.
REPOSITORY
rHG Mercurial
CHANGES SINCE LAST UPDATE
https://phab.mercurial-scm.org/D7815?vs=19119&id=19188
BRANCH
default
CHANGES SINCE LAST ACTION
https://phab.mercurial-scm.org/D7815/new/
REVISION DETAIL
https://phab.mercurial-scm.org/D7815
AFFECTED FILES
mercurial/thirdparty/sha1dc/cext.c
setup.py
tests/test-hashutil.py
CHANGE DETAILS
diff --git a/tests/test-hashutil.py b/tests/test-hashutil.py
new file mode 100644
--- /dev/null
+++ b/tests/test-hashutil.py
@@ -0,0 +1,60 @@
+# Tests to ensure that sha1dc.sha1 is exactly a drop-in for
+# hashlib.sha1 for our needs.
+from __future__ import absolute_import
+
+import hashlib
+import unittest
+
+import silenttestrunner
+
+try:
+ from mercurial.thirdparty import sha1dc
+except ImportError:
+ sha1dc = None
+
+
+class hashertestsbase(object):
+ def test_basic_hash(self):
+ h = self.hasher()
+ h.update(b'foo')
+ self.assertEqual(
+ '0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33', h.hexdigest()
+ )
+ h.update(b'bar')
+ self.assertEqual(
+ '8843d7f92416211de9ebb963ff4ce28125932878', h.hexdigest()
+ )
+
+ def test_copy_hasher(self):
+ h = self.hasher()
+ h.update(b'foo')
+ h2 = h.copy()
+ h.update(b'baz')
+ h2.update(b'bar')
+ self.assertEqual(
+ '21eb6533733a5e4763acacd1d45a60c2e0e404e1', h.hexdigest()
+ )
+ self.assertEqual(
+ '8843d7f92416211de9ebb963ff4ce28125932878', h2.hexdigest()
+ )
+
+ def test_init_hasher(self):
+ h = self.hasher(b'initial string')
+ self.assertEqual(
+ b'\xc9y|n\x1f3S\xa4:\xbaJ\xca,\xc1\x1a\x9e\xb8\xd8\xdd\x86',
+ h.digest(),
+ )
+
+
+class hashlibtests(unittest.TestCase, hashertestsbase):
+ hasher = hashlib.sha1
+
+
+if sha1dc:
+
+ class sha1dctests(unittest.TestCase, hashertestsbase):
+ hasher = sha1dc.sha1
+
+
+if __name__ == '__main__':
+ silenttestrunner.main(__name__)
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -1481,6 +1481,14 @@
],
),
Extension(
+ 'mercurial.thirdparty.sha1dc',
+ [
+ 'mercurial/thirdparty/sha1dc/cext.c',
+ 'mercurial/thirdparty/sha1dc/lib/sha1.c',
+ 'mercurial/thirdparty/sha1dc/lib/ubc_check.c',
+ ],
+ ),
+ Extension(
'hgext.fsmonitor.pywatchman.bser', ['hgext/fsmonitor/pywatchman/bser.c']
),
RustStandaloneExtension(
diff --git a/mercurial/thirdparty/sha1dc/cext.c b/mercurial/thirdparty/sha1dc/cext.c
new file mode 100644
--- /dev/null
+++ b/mercurial/thirdparty/sha1dc/cext.c
@@ -0,0 +1,197 @@
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+
+#include "lib/sha1.h"
+
+#if PY_MAJOR_VERSION >= 3
+#define IS_PY3K
+#endif
+
+/* helper to switch things like string literal depending on Python version */
+#ifdef IS_PY3K
+#define PY23(py2, py3) py3
+#else
+#define PY23(py2, py3) py2
+#endif
+
+static char sha1dc_doc[] = "Efficient detection of SHA1 collision constructs.";
+
+/* clang-format off */
+typedef struct {
+ PyObject_HEAD
+ SHA1_CTX ctx;
+} pysha1ctx;
+/* clang-format on */
+
+static int pysha1ctx_init(pysha1ctx *self, PyObject *args)
+{
+ const char *data = NULL;
+ Py_ssize_t len;
+
+ SHA1DCInit(&(self->ctx));
+ /* We don't want "safe" sha1s, wherein sha1dc can give you a
+ different hash for something that's trying to give you a
+ collision. We just want to detect collisions.
+ */
+ SHA1DCSetSafeHash(&(self->ctx), 0);
+ if (!PyArg_ParseTuple(args, PY23("|s#", "|y#"), &data, &len)) {
+ return -1;
+ }
+ if (data) {
+ SHA1DCUpdate(&(self->ctx), data, len);
+ }
+ return 0;
+}
+
+static void pysha1ctx_dealloc(pysha1ctx *self)
+{
+ PyObject_Del(self);
+}
+
+static PyObject *pysha1ctx_update(pysha1ctx *self, PyObject *args)
+{
+ const char *data;
+ Py_ssize_t len;
+ if (!PyArg_ParseTuple(args, PY23("s#", "y#"), &data, &len)) {
+ return NULL;
+ }
+ SHA1DCUpdate(&(self->ctx), data, len);
+ Py_RETURN_NONE;
+}
+
+/* it is intentional that this take a ctx by value, as that clones the
+ context so we can keep using .update() without poisoning the state
+ with padding.
+*/
+static int finalize(SHA1_CTX ctx, unsigned char *hash_out)
+{
+ if (SHA1DCFinal(hash_out, &ctx)) {
+ PyErr_SetString(PyExc_OverflowError,
+ "sha1 collision attack detected");
+ return 0;
+ }
+ return 1;
+}
+
+static PyObject *pysha1ctx_digest(pysha1ctx *self)
+{
+ unsigned char hash[20];
+ if (!finalize(self->ctx, hash)) {
+ return NULL;
+ }
+ return PyBytes_FromStringAndSize((char *)hash, 20);
+}
+
+static PyObject *pysha1ctx_hexdigest(pysha1ctx *self)
+{
+ unsigned char hash[20];
+ if (!finalize(self->ctx, hash)) {
+ return NULL;
+ }
+ char hexhash[40];
+ static const char hexdigit[] = "0123456789abcdef";
+ for (int i = 0; i < 20; ++i) {
+ hexhash[i * 2] = hexdigit[hash[i] >> 4];
+ hexhash[i * 2 + 1] = hexdigit[hash[i] & 15];
+ }
+ return PyString_FromStringAndSize(hexhash, 40);
+}
+
+static PyTypeObject sha1ctxType;
+
+static PyObject *pysha1ctx_copy(pysha1ctx *self)
+{
+ pysha1ctx *clone = (pysha1ctx *)PyObject_New(pysha1ctx, &sha1ctxType);
+ if (!clone) {
+ return NULL;
+ }
+ clone->ctx = self->ctx;
+ return (PyObject *)clone;
+}
+
+static PyMethodDef pysha1ctx_methods[] = {
+ {"update", (PyCFunction)pysha1ctx_update, METH_VARARGS,
+ "Update this hash object's state with the provided bytes."},
+ {"digest", (PyCFunction)pysha1ctx_digest, METH_NOARGS,
+ "Return the digest value as a string of binary data."},
+ {"hexdigest", (PyCFunction)pysha1ctx_hexdigest, METH_NOARGS,
+ "Return the digest value as a string of hexadecimal digits."},
+ {"copy", (PyCFunction)pysha1ctx_copy, METH_NOARGS,
+ "Return a copy of the hash object."},
+ {NULL},
+};
+
+/* clang-format off */
+static PyTypeObject sha1ctxType = {
+ PyVarObject_HEAD_INIT(NULL, 0) /* header */
+ "sha1dc.sha1", /* tp_name */
+ sizeof(pysha1ctx), /* tp_basicsize */
+ 0, /* tp_itemsize */
+ (destructor)pysha1ctx_dealloc, /* tp_dealloc */
+ 0, /* tp_print */
+ 0, /* tp_getattr */
+ 0, /* tp_setattr */
+ 0, /* tp_compare */
+ 0, /* 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, /* tp_flags */
+ "sha1 implementation that looks for collisions", /* tp_doc */
+ 0, /* tp_traverse */
+ 0, /* tp_clear */
+ 0, /* tp_richcompare */
+ 0, /* tp_weaklistoffset */
+ 0, /* tp_iter */
+ 0, /* tp_iternext */
+ pysha1ctx_methods, /* tp_methods */
+ 0, /* tp_members */
+ 0, /* tp_getset */
+ 0, /* tp_base */
+ 0, /* tp_dict */
+ 0, /* tp_descr_get */
+ 0, /* tp_descr_set */
+ 0, /* tp_dictoffset */
+ (initproc)pysha1ctx_init, /* tp_init */
+ 0, /* tp_alloc */
+};
+/* clang-format on */
+
+static PyMethodDef methods[] = {
+ {NULL, NULL},
+};
+
+static void module_init(PyObject *mod)
+{
+ sha1ctxType.tp_new = PyType_GenericNew;
+ if (PyType_Ready(&sha1ctxType) < 0) {
+ return;
+ }
+ Py_INCREF(&sha1ctxType);
+
+ PyModule_AddObject(mod, "sha1", (PyObject *)&sha1ctxType);
+}
+
+#ifdef IS_PY3K
+static struct PyModuleDef sha1dc_module = {PyModuleDef_HEAD_INIT, "sha1dc",
+ sha1dc_doc, -1, methods};
+
+PyMODINIT_FUNC PyInit_sha1dc(void)
+{
+ PyObject *mod = PyModule_Create(&sha1dc_module);
+ module_init(mod);
+ return mod;
+}
+#else
+PyMODINIT_FUNC initsha1dc(void)
+{
+ PyObject *mod = Py_InitModule3("sha1dc", methods, sha1dc_doc);
+ module_init(mod);
+}
+#endif
To: durin42, #hg-reviewers
Cc: indygreg, spectral, mjpieters, mercurial-devel
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