rtnl_mdb: decode messages regardless of availability of kernel headers

[strace] / rtnl_mdb.c

diff --git a/rtnl_mdb.c b/rtnl_mdb.c
index dbbfb8961e04dad64694967105b1a36c6f7843f5..5c7ed34be4c6af77313a1291f4fbdda293ef6f55 100644 (file)
--- a/rtnl_mdb.c
+++ b/rtnl_mdb.c
@@ -9,27 +9,52 @@
 
 #include "defs.h"
 
+#include "netlink_route.h"
+#include "nlattr.h"
+#include "print_fields.h"
+
+#include <netinet/in.h>
+#include <linux/if_bridge.h>
+#include "netlink.h"
+
+#include "xlat/mdb_flags.h"
+#include "xlat/mdb_states.h"
+#include "xlat/multicast_router_types.h"
+#include "xlat/rtnl_mdb_attrs.h"
+#include "xlat/rtnl_mdba_mdb_attrs.h"
+#include "xlat/rtnl_mdba_mdb_eattr_attrs.h"
+#include "xlat/rtnl_mdba_mdb_entry_attrs.h"
+#include "xlat/rtnl_mdba_router_attrs.h"
+#include "xlat/rtnl_mdba_router_pattr_attrs.h"
+
+typedef struct {
+       uint8_t  family;
+       uint32_t ifindex;
+} struct_br_port_msg;
+
+typedef struct {
+       uint32_t ifindex;
+       uint8_t  state;
+       uint8_t  flags;
+       uint16_t vid;
+       struct {
+               union {
+                       uint32_t /* __be32 */ ip4;
+                       struct in6_addr       ip6;
+               } u;
+               uint16_t /* __be16 */ proto;
+       } addr;
+} struct_br_mdb_entry;
+
 #ifdef HAVE_STRUCT_BR_PORT_MSG
+static_assert(sizeof(struct br_port_msg) <= sizeof(struct_br_port_msg),
+             "Unexpected struct br_port_msg size, please update the decoder");
+#endif
 
-# include "netlink_route.h"
-# include "nlattr.h"
-# include "print_fields.h"
-
-# include <netinet/in.h>
-# include <linux/if_bridge.h>
-# include "netlink.h"
-
-# ifdef HAVE_STRUCT_BR_MDB_ENTRY_FLAGS
-#  include "xlat/mdb_flags.h"
-# endif
-# include "xlat/mdb_states.h"
-# include "xlat/multicast_router_types.h"
-# include "xlat/rtnl_mdb_attrs.h"
-# include "xlat/rtnl_mdba_mdb_attrs.h"
-# include "xlat/rtnl_mdba_mdb_eattr_attrs.h"
-# include "xlat/rtnl_mdba_mdb_entry_attrs.h"
-# include "xlat/rtnl_mdba_router_attrs.h"
-# include "xlat/rtnl_mdba_router_pattr_attrs.h"
+#ifdef HAVE_STRUCT_BR_NDB_ENTRY
+static_assert(sizeof(struct br_mdb_entry) <= sizeof(struct_br_mdb_entry),
+             "Unexpected struct br_mdb_entry size, please update the decoder");
+#endif
 
 static const nla_decoder_t mdba_mdb_eattr_nla_decoders[] = {
        [MDBA_MDB_EATTR_TIMER]  = decode_nla_u32
@@ -41,21 +66,22 @@ decode_mdba_mdb_entry_info(struct tcb *const tcp,
                           const unsigned int len,
                           const void *const opaque_data)
 {
-# ifdef HAVE_STRUCT_BR_MDB_ENTRY
-       struct br_mdb_entry entry;
+       struct_br_mdb_entry entry;
 
        if (len < sizeof(entry))
                return false;
        else if (!umove_or_printaddr(tcp, addr, &entry)) {
                PRINT_FIELD_IFINDEX("{", entry, ifindex);
                PRINT_FIELD_XVAL(", ", entry, state, mdb_states, "MDB_???");
-#  ifdef HAVE_STRUCT_BR_MDB_ENTRY_FLAGS
+
+               /*
+                * Note that it's impossible to derive if flags/vid fields
+                * are present on all architectures except m68k; as a side note,
+                * v4.3-rc1~96^2~365 has introduced an ABI breakage on m68k.
+                */
                PRINT_FIELD_FLAGS(", ", entry, flags,
                                  mdb_flags, "MDB_FLAGS_???");
-#  endif
-#  ifdef HAVE_STRUCT_BR_MDB_ENTRY_VID
                PRINT_FIELD_U(", ", entry, vid);
-#  endif
 
                const int proto = ntohs(entry.addr.proto);
 
@@ -77,9 +103,6 @@ decode_mdba_mdb_entry_info(struct tcb *const tcp,
        }
 
        return true;
-# else
-       return false;
-# endif /* HAVE_STRUCT_BR_MDB_ENTRY */
 }
 
 static const nla_decoder_t mdba_mdb_entry_nla_decoders[] = {
@@ -185,7 +208,7 @@ static const nla_decoder_t br_port_msg_nla_decoders[] = {
 
 DECL_NETLINK_ROUTE_DECODER(decode_br_port_msg)
 {
-       struct br_port_msg bpm = { .family = family };
+       struct_br_port_msg bpm = { .family = family };
        size_t offset = sizeof(bpm.family);
        bool decode_nla = false;
 
@@ -212,5 +235,3 @@ DECL_NETLINK_ROUTE_DECODER(decode_br_port_msg)
                              ARRAY_SIZE(br_port_msg_nla_decoders), NULL);
        }
 }
-
-#endif