include/openvswitch/tun-metadata.h

   1 /*
   2  * Copyright (c) 2015 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef OPENVSWITCH_TUN_METADATA_H
  18 #define OPENVSWITCH_TUN_METADATA_H 1
  19
  20 #include "openvswitch/geneve.h"
  21
  22 #define TUN_METADATA_NUM_OPTS 64
  23 #define TUN_METADATA_TOT_OPT_SIZE 256
  24
  25 /* Tunnel option data, plus metadata to aid in their interpretation.
  26  *
  27  * The option data exists in two forms and is interpreted differently depending
  28  * on whether FLOW_TNL_F_UDPIF is set in struct flow_tnl flags:
  29  *
  30  * When FLOW_TNL_F_UDPIF is set, the tunnel metadata is in "userspace datapath
  31  * format". This is typically used for fast-path packet processing to avoid
  32  * the cost of translating options and in situations where we need to maintain
  33  * tunnel metadata exactly as it came in. In this case 'opts.gnv' is raw
  34  * packet data from the tunnel header and 'present.len' indicates the length
  35  * of the data stored there. In these situations, 'tab' is NULL.
  36  *
  37  * In all other cases, we are doing flow-based processing (such as during
  38  * upcalls). FLOW_TNL_F_UDPIF is not set and options are reordered into
  39  * pre-allocated locations. 'present.map' is indexed by type, that is, by the
  40  * <i> in TUN_METADATA<i>, so that e.g. TUN_METADATA5 is present if
  41  * 'present.map & (1ULL << 5)' is nonzero. The actual data for TUN_METADATA5,
  42  * if present, might be anywhere in 'opts.u8' (not necessarily even contiguous),
  43  * and finding it requires referring to 'tab', if set, or the global metadata
  44  * table. */
  45 struct tun_metadata {
  46     union { /* Valid members of 'opts'. When 'opts' is sorted into known types,
  47              * 'map' is used. When 'opts' is raw packet data, 'len' is used. */
  48         uint64_t map;                      /* 1-bit for each present TLV. */
  49         uint8_t len;                       /* Length of data in 'opts'. */
  50     } present;
  51     struct tun_table *tab;      /* Types & lengths for 'opts' and 'opt_map'. */
  52
  53 #if UINTPTR_MAX == UINT32_MAX
  54     uint8_t pad[4];             /* Pad to 64-bit boundary. */
  55 #endif
  56
  57     union {
  58         uint8_t u8[TUN_METADATA_TOT_OPT_SIZE]; /* Values from tunnel TLVs. */
  59         struct geneve_opt gnv[TLV_TOT_OPT_SIZE / sizeof(struct geneve_opt)];
  60     } opts;
  61 };
  62 BUILD_ASSERT_DECL(offsetof(struct tun_metadata, opts) % 8 == 0);
  63 BUILD_ASSERT_DECL(sizeof(((struct tun_metadata *)0)->present.map) * 8 >=
  64                   TUN_METADATA_NUM_OPTS);
  65
  66 /* The location of an option can be stored either as a single offset/len
  67  * pair (hopefully) or if the address space is fragmented then it is a
  68  * linked list of these blocks. */
  69 struct tun_metadata_loc_chain {
  70     struct tun_metadata_loc_chain *next;
  71     int offset;       /* In bytes, from start of 'opts', multiple of 4.  */
  72     int len;          /* In bytes, multiple of 4. */
  73 };
  74
  75 struct tun_metadata_loc {
  76     int len;                    /* Sum of 'len' over elements in chain. */
  77     struct tun_metadata_loc_chain c;
  78 };
  79
  80 /* Bookkeeping information to keep track of an option that was allocated
  81  * inside struct match. */
  82 struct tun_metadata_match_entry {
  83     struct tun_metadata_loc loc; /* Allocated position. */
  84     bool masked; /* Source value had a mask. Otherwise we can't tell if the
  85                   * entire field was exact matched or only the portion that
  86                   * is the same size as the value. */
  87 };
  88
  89 /* Allocation of options inside struct match.  This is important if we don't
  90  * have access to a global allocation table - either because there isn't one
  91  * (ovs-ofctl) or if we need to keep the allocation outside of packet
  92  * processing context (Packet-In). These structures never have dynamically
  93  * allocated memory because the address space is never fragmented. */
  94 struct tun_metadata_allocation {
  95     struct tun_metadata_match_entry entry[TUN_METADATA_NUM_OPTS];
  96     int alloc_offset;           /* Byte offset into 'opts', multiple of 4.  */
  97     bool valid;                 /* Set to true after any allocation occurs. */
  98 };
  99
 100
 101 #endif /* tun-metadata.h */