Support NetBSD's socketcan implementation

--- configure.orig	2017-03-21 07:32:38.000000000 +0100
+++ configure	2017-05-30 12:34:22.173986489 +0200
@@ -8072,7 +8072,7 @@
 
 
 # On Linux, can.h and can/raw.h require sys/socket.h
-for ac_header in linux/can.h linux/can/raw.h linux/can/bcm.h
+for ac_header in linux/can.h linux/can/raw.h linux/can/bcm.h netcan/can.h
 do :
   as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
 ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "

--- Modules/socketmodule.c.orig	2017-05-30 13:31:59.096006411 +0200
+++ Modules/socketmodule.c	2017-05-30 13:37:39.696032387 +0200
@@ -1405,8 +1405,13 @@
         /* need to look up interface name given index */
         if (a->can_ifindex) {
             ifr.ifr_ifindex = a->can_ifindex;
+#ifdef __NetBSD__
+            if (if_indextoname(a->can_ifindex, ifr.ifr_name) != NULL)
+                ifname = ifr.ifr_name;
+#else
             if (ioctl(sockfd, SIOCGIFNAME, &ifr) == 0)
                 ifname = ifr.ifr_name;
+#endif /* __NetBSD__ */
         }
 
         return Py_BuildValue("O&h", PyUnicode_DecodeFSDefault,
@@ -1905,12 +1910,14 @@
     }
 #endif
 
-#if defined(AF_CAN) && defined(CAN_RAW) && defined(CAN_BCM)
+#if defined(AF_CAN) && defined(CAN_RAW)
     case AF_CAN:
         switch (s->sock_proto) {
         case CAN_RAW:
+#ifdef CAN_BCM
         /* fall-through */
         case CAN_BCM:
+#endif
         {
             struct sockaddr_can *addr;
             PyObject *interfaceName;
@@ -1930,7 +1937,12 @@
             } 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) {
+#ifdef __NetBSD__
+                if ((ifr.ifr_ifindex = if_nametoindex(ifr.ifr_name)) == 0)
+#else
+                if (ioctl(s->sock_fd, SIOCGIFINDEX, &ifr) < 0)
+#endif
+		{
                     s->errorhandler();
                     Py_DECREF(interfaceName);
                     return 0;
@@ -7136,6 +7148,20 @@
     PyModule_AddIntConstant(m, "CAN_BCM_RX_TIMEOUT", RX_TIMEOUT);
     PyModule_AddIntConstant(m, "CAN_BCM_RX_CHANGED", RX_CHANGED);
 #endif
+#ifdef HAVE_NETCAN_CAN_H
+    PyModule_AddIntMacro(m, CAN_EFF_FLAG);
+    PyModule_AddIntMacro(m, CAN_RTR_FLAG);
+    PyModule_AddIntMacro(m, CAN_ERR_FLAG);
+
+    PyModule_AddIntMacro(m, CAN_SFF_MASK);
+    PyModule_AddIntMacro(m, CAN_EFF_MASK);
+    PyModule_AddIntMacro(m, CAN_ERR_MASK);
+
+    PyModule_AddIntMacro(m, CAN_RAW_FILTER);
+    /* PyModule_AddIntMacro(m, CAN_RAW_ERR_FILTER); */
+    PyModule_AddIntMacro(m, CAN_RAW_LOOPBACK);
+    PyModule_AddIntMacro(m, CAN_RAW_RECV_OWN_MSGS);
+#endif
 #ifdef SOL_RDS
     PyModule_AddIntMacro(m, SOL_RDS);
 #endif

--- Modules/socketmodule.h.orig	2017-03-21 07:32:38.000000000 +0100
+++ Modules/socketmodule.h	2017-05-30 12:36:59.254776235 +0200
@@ -91,6 +91,10 @@
 #include <linux/can/bcm.h>
 #endif
 
+#ifdef HAVE_NETCAN_CAN_H
+#include <netcan/can.h>
+#endif
+
 #ifdef HAVE_SYS_SYS_DOMAIN_H
 #include <sys/sys_domain.h>
 #endif

--- pyconfig.h.in.orig	2017-05-30 12:31:24.586818399 +0200
+++ pyconfig.h.in	2017-05-30 12:32:29.367288479 +0200
@@ -565,6 +565,9 @@
 /* Define to 1 if you have the <linux/can/raw.h> header file. */
 #undef HAVE_LINUX_CAN_RAW_H
 
+/* Define to 1 if you have the <netcan/can.h> header file. */
+#undef HAVE_NETCAN_CAN_H
+
 /* Define to 1 if you have the <linux/netlink.h> header file. */
 #undef HAVE_LINUX_NETLINK_H