bpo-30987 - Support for ISO-TP protocol in SocketCAN (python#2956)

* Added support for CAN_ISOTP protocol

* Added unit tests for CAN ISOTP

* Updated documentation for ISO-TP protocol

* Removed trailing whitespace in documentation

* Added blurb NEWS.d file

* updated Misc/ACKS

* Fixed broken unit test that was using isotp const outside of skippable section

* Removed dependecy over third party project

* Added implementation for getsockname + unit tests

* Missing newline at end of ACKS file

* Accidentally inserted a type in ACKS file

* Followed tiran changes review #1 recommendations

* Added spaces after comma

Author: pylessard

Doc/library/socket.rst

@@ -103,6 +103,10 @@ created.  Socket addresses are represented as follows:
   ``'can0'``. The network interface name ``''`` can be used to receive packets
   from all network interfaces of this family.
 
+  - :const:`CAN_ISOTP` protocol require a tuple ``(interface, rx_addr, tx_addr)``
+    where both additional parameters are unsigned long integer that represent a
+    CAN identifier (standard or extended).
+
 - A string or a tuple ``(id, unit)`` is used for the :const:`SYSPROTO_CONTROL`
   protocol of the :const:`PF_SYSTEM` family. The string is the name of a
   kernel control using a dynamically-assigned ID. The tuple can be used if ID
@@ -341,6 +345,16 @@ Constants
 
    .. versionadded:: 3.5
 
+.. data:: CAN_ISOTP
+
+   CAN_ISOTP, in the CAN protocol family, is the ISO-TP (ISO 15765-2) protocol.
+   ISO-TP constants, documented in the Linux documentation.
+
+   Availability: Linux >= 2.6.25
+
+   .. versionadded:: 3.7
+
+
 .. data:: AF_RDS
           PF_RDS
           SOL_RDS
@@ -427,7 +441,7 @@ The following functions all create :ref:`socket objects <socket-objects>`.
    :const:`SOCK_DGRAM`, :const:`SOCK_RAW` or perhaps one of the other ``SOCK_``
    constants. The protocol number is usually zero and may be omitted or in the
    case where the address family is :const:`AF_CAN` the protocol should be one
-   of :const:`CAN_RAW` or :const:`CAN_BCM`.  If *fileno* is specified, the other
+   of :const:`CAN_RAW`, :const:`CAN_BCM` or :const:`CAN_ISOTP`.  If *fileno* is specified, the other
    arguments are ignored, causing the socket with the specified file descriptor
    to return.  Unlike :func:`socket.fromfd`, *fileno* will return the same
    socket and not a duplicate. This may help close a detached socket using
@@ -445,6 +459,8 @@ The following functions all create :ref:`socket objects <socket-objects>`.
    .. versionchanged:: 3.4
       The returned socket is now non-inheritable.
 
+   .. versionchanged:: 3.7
+       The CAN_ISOTP protocol was added.
 
 .. function:: socketpair([family[, type[, proto]]])
 
@@ -1661,7 +1677,7 @@ the interface::
    # disabled promiscuous mode
    s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)
 
-The last example shows how to use the socket interface to communicate to a CAN
+The next example shows how to use the socket interface to communicate to a CAN
 network using the raw socket protocol. To use CAN with the broadcast
 manager protocol instead, open a socket with::
 
@@ -1671,7 +1687,7 @@ After binding (:const:`CAN_RAW`) or connecting (:const:`CAN_BCM`) the socket, yo
 can use the :meth:`socket.send`, and the :meth:`socket.recv` operations (and
 their counterparts) on the socket object as usual.
 
-This example might require special privileges::
+This last example might require special privileges::
 
    import socket
    import struct

Lib/test/test_socket.py

@@ -55,6 +55,16 @@ def _have_socket_can():
         s.close()
     return True
 
+def _have_socket_can_isotp():
+    """Check whether CAN ISOTP sockets are supported on this host."""
+    try:
+        s = socket.socket(socket.PF_CAN, socket.SOCK_DGRAM, socket.CAN_ISOTP)
+    except (AttributeError, OSError):
+        return False
+    else:
+        s.close()
+    return True
+
 def _have_socket_rds():
     """Check whether RDS sockets are supported on this host."""
     try:
@@ -77,6 +87,8 @@ def _have_socket_alg():
 
 HAVE_SOCKET_CAN = _have_socket_can()
 
+HAVE_SOCKET_CAN_ISOTP = _have_socket_can_isotp()
+
 HAVE_SOCKET_RDS = _have_socket_rds()
 
 HAVE_SOCKET_ALG = _have_socket_alg()
@@ -1709,6 +1721,49 @@ def testBCM(self):
         self.assertEqual(bytes_sent, len(header_plus_frame))
 
 
+@unittest.skipUnless(HAVE_SOCKET_CAN_ISOTP, 'CAN ISOTP required for this test.')
+class ISOTPTest(unittest.TestCase):
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.interface = "vcan0"
+
+    def testCrucialConstants(self):
+        socket.AF_CAN
+        socket.PF_CAN
+        socket.CAN_ISOTP
+        socket.SOCK_DGRAM
+
+    def testCreateSocket(self):
+        with socket.socket(socket.PF_CAN, socket.SOCK_RAW, socket.CAN_RAW) as s:
+            pass
+
+    @unittest.skipUnless(hasattr(socket, "CAN_ISOTP"),
+                         'socket.CAN_ISOTP required for this test.')
+    def testCreateISOTPSocket(self):
+        with socket.socket(socket.PF_CAN, socket.SOCK_DGRAM, socket.CAN_ISOTP) as s:
+            pass
+
+    def testTooLongInterfaceName(self):
+        # most systems limit IFNAMSIZ to 16, take 1024 to be sure
+        with socket.socket(socket.PF_CAN, socket.SOCK_DGRAM, socket.CAN_ISOTP) as s:
+            with self.assertRaisesRegex(OSError, 'interface name too long'):
+                s.bind(('x' * 1024, 1, 2))
+
+    def testBind(self):
+        try:
+            with socket.socket(socket.PF_CAN, socket.SOCK_DGRAM, socket.CAN_ISOTP) as s:
+                addr = self.interface, 0x123, 0x456
+                s.bind(addr)
+                self.assertEqual(s.getsockname(), addr)
+        except OSError as e:
+            if e.errno == errno.ENODEV:
+                self.skipTest('network interface `%s` does not exist' %
+                           self.interface)
+            else:
+                raise
+
+
 @unittest.skipUnless(HAVE_SOCKET_RDS, 'RDS sockets required for this test.')
 class BasicRDSTest(unittest.TestCase):
 

Misc/ACKS

@@ -908,6 +908,7 @@ John Lenton
 Kostyantyn Leschenko
 Benno Leslie
 Christopher Tur Lesniewski-Laas
+Pier-Yves Lessard
 Alain Leufroy
 Mark Levinson
 Mark Levitt

Misc/NEWS.d/next/Library/2017-07-30-22-00-12.bpo-30987.228rW0.rst

@@ -0,0 +1 @@
+Added support for CAN ISO-TP protocol in the socket module.

Modules/socketmodule.c

@@ -1373,9 +1373,22 @@ makesockaddr(SOCKET_T sockfd, struct sockaddr *addr, size_t addrlen, int proto)
                 ifname = ifr.ifr_name;
         }
 
-        return Py_BuildValue("O&h", PyUnicode_DecodeFSDefault,
-                                    ifname,
-                                    a->can_family);
+        switch (proto) {
+#ifdef CAN_ISOTP
+          case CAN_ISOTP:
+          {
+              return Py_BuildValue("O&kk", PyUnicode_DecodeFSDefault,
+                                          ifname,
+                                          a->can_addr.tp.rx_id,
+                                          a->can_addr.tp.tx_id);
+          }
+#endif
+          default:
+          {
+              return Py_BuildValue("O&", PyUnicode_DecodeFSDefault,
+                                        ifname);
+          }
+        }
     }
 #endif
 
@@ -1869,7 +1882,9 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
     }
 #endif
 
-#if defined(AF_CAN) && defined(CAN_RAW) && defined(CAN_BCM)
+#ifdef AF_CAN
+
+#if defined(CAN_RAW) && defined(CAN_BCM)
     case AF_CAN:
         switch (s->sock_proto) {
         case CAN_RAW:
@@ -1880,7 +1895,6 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             PyObject *interfaceName;
             struct ifreq ifr;
             Py_ssize_t len;
-
             addr = (struct sockaddr_can *)addr_ret;
 
             if (!PyArg_ParseTuple(args, "O&", PyUnicode_FSConverter,
@@ -1913,6 +1927,54 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
             Py_DECREF(interfaceName);
             return 1;
         }
+#endif
+
+#ifdef CAN_ISOTP
+        case CAN_ISOTP:
+        {
+            struct sockaddr_can *addr;
+            PyObject *interfaceName;
+            struct ifreq ifr;
+            Py_ssize_t len;
+            unsigned long int rx_id, tx_id;
+
+            addr = (struct sockaddr_can *)addr_ret;
+
+            if (!PyArg_ParseTuple(args, "O&kk", PyUnicode_FSConverter,
+                                              &interfaceName,
+                                              &rx_id,
+                                              &tx_id))
+                return 0;
+
+            len = PyBytes_GET_SIZE(interfaceName);
+
+            if (len == 0) {
+                ifr.ifr_ifindex = 0;
+            } else if ((size_t)len < sizeof(ifr.ifr_name)) {
+                strncpy(ifr.ifr_name, PyBytes_AS_STRING(interfaceName), sizeof(ifr.ifr_name));
+                ifr.ifr_name[(sizeof(ifr.ifr_name))-1] = '\0';
+                if (ioctl(s->sock_fd, SIOCGIFINDEX, &ifr) < 0) {
+                    s->errorhandler();
+                    Py_DECREF(interfaceName);
+                    return 0;
+                }
+            } else {
+                PyErr_SetString(PyExc_OSError,
+                                "AF_CAN interface name too long");
+                Py_DECREF(interfaceName);
+                return 0;
+            }
+
+            addr->can_family = AF_CAN;
+            addr->can_ifindex = ifr.ifr_ifindex;
+            addr->can_addr.tp.rx_id = rx_id;
+            addr->can_addr.tp.tx_id = tx_id;
+
+            *len_ret = sizeof(*addr);
+            Py_DECREF(interfaceName);
+            return 1;
+        }
+#endif
         default:
             PyErr_SetString(PyExc_OSError,
                             "getsockaddrarg: unsupported CAN protocol");
@@ -6995,6 +7057,9 @@ PyInit__socket(void)
     PyModule_AddIntMacro(m, CAN_SFF_MASK);
     PyModule_AddIntMacro(m, CAN_EFF_MASK);
     PyModule_AddIntMacro(m, CAN_ERR_MASK);
+#ifdef CAN_ISOTP
+    PyModule_AddIntMacro(m, CAN_ISOTP);
+#endif
 #endif
 #ifdef HAVE_LINUX_CAN_RAW_H
     PyModule_AddIntMacro(m, CAN_RAW_FILTER);