lib/netlink.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011, 2013, 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 NETLINK_H
  18 #define NETLINK_H 1
  19
  20 /* Netlink message helpers.
  21  *
  22  * Netlink is a datagram-based network protocol primarily for communication
  23  * between user processes and the kernel, and mainly on Linux.  Netlink is
  24  * specified in RFC 3549, "Linux Netlink as an IP Services Protocol".
  25  *
  26  * Netlink is not suitable for use in physical networks of heterogeneous
  27  * machines because host byte order is used throughout.
  28  *
  29  * This header file defines helper functions for working with Netlink messages.
  30  * For Netlink protocol definitions, see netlink-protocol.h.  For
  31  * Linux-specific definitions for Netlink sockets, see netlink-socket.h.
  32  */
  33
  34 #include <netinet/in.h>
  35 #include <stdbool.h>
  36 #include <stddef.h>
  37 #include <stdint.h>
  38 #include "netlink-protocol.h"
  39 #include "openvswitch/types.h"
  40
  41 struct ofpbuf;
  42 struct nlattr;
  43
  44 /* Accessing headers and data. */
  45 struct nlmsghdr *nl_msg_nlmsghdr(const struct ofpbuf *);
  46 struct genlmsghdr *nl_msg_genlmsghdr(const struct ofpbuf *);
  47 bool nl_msg_nlmsgerr(const struct ofpbuf *, int *error);
  48 void nl_msg_reserve(struct ofpbuf *, size_t);
  49
  50 /* Appending and prepending headers and raw data. */
  51 void nl_msg_put_nlmsghdr(struct ofpbuf *, size_t expected_payload,
  52                          uint32_t type, uint32_t flags);
  53 void nl_msg_put_genlmsghdr(struct ofpbuf *, size_t expected_payload,
  54                            int family, uint32_t flags,
  55                            uint8_t cmd, uint8_t version);
  56 void nl_msg_put(struct ofpbuf *, const void *, size_t);
  57 void *nl_msg_put_uninit(struct ofpbuf *, size_t);
  58 void nl_msg_push(struct ofpbuf *, const void *, size_t);
  59 void *nl_msg_push_uninit(struct ofpbuf *, size_t);
  60
  61 /* Appending attributes. */
  62 void *nl_msg_put_unspec_uninit(struct ofpbuf *, uint16_t type, size_t);
  63 void *nl_msg_put_unspec_zero(struct ofpbuf *, uint16_t type, size_t);
  64 void nl_msg_put_unspec(struct ofpbuf *, uint16_t type, const void *, size_t);
  65 void nl_msg_put_flag(struct ofpbuf *, uint16_t type);
  66 void nl_msg_put_u8(struct ofpbuf *, uint16_t type, uint8_t value);
  67 void nl_msg_put_u16(struct ofpbuf *, uint16_t type, uint16_t value);
  68 void nl_msg_put_u32(struct ofpbuf *, uint16_t type, uint32_t value);
  69 void nl_msg_put_u64(struct ofpbuf *, uint16_t type, uint64_t value);
  70 void nl_msg_put_be16(struct ofpbuf *, uint16_t type, ovs_be16 value);
  71 void nl_msg_put_be32(struct ofpbuf *, uint16_t type, ovs_be32 value);
  72 void nl_msg_put_be64(struct ofpbuf *, uint16_t type, ovs_be64 value);
  73 void nl_msg_put_in6_addr(struct ofpbuf *msg, uint16_t type,
  74                          const struct in6_addr *value);
  75 void nl_msg_put_odp_port(struct ofpbuf *, uint16_t type, odp_port_t value);
  76 void nl_msg_put_string__(struct ofpbuf *, uint16_t type, const char *value,
  77                          size_t len);
  78 void nl_msg_put_string(struct ofpbuf *, uint16_t type, const char *value);
  79
  80 size_t nl_msg_start_nested(struct ofpbuf *, uint16_t type);
  81 void nl_msg_end_nested(struct ofpbuf *, size_t offset);
  82 void nl_msg_end_non_empty_nested(struct ofpbuf *, size_t offset);
  83 void nl_msg_put_nested(struct ofpbuf *, uint16_t type,
  84                        const void *data, size_t size);
  85
  86 /* Prepending attributes. */
  87 void *nl_msg_push_unspec_uninit(struct ofpbuf *, uint16_t type, size_t);
  88 void nl_msg_push_unspec(struct ofpbuf *, uint16_t type, const void *, size_t);
  89 void nl_msg_push_flag(struct ofpbuf *, uint16_t type);
  90 void nl_msg_push_u8(struct ofpbuf *, uint16_t type, uint8_t value);
  91 void nl_msg_push_u16(struct ofpbuf *, uint16_t type, uint16_t value);
  92 void nl_msg_push_u32(struct ofpbuf *, uint16_t type, uint32_t value);
  93 void nl_msg_push_u64(struct ofpbuf *, uint16_t type, uint64_t value);
  94 void nl_msg_push_be16(struct ofpbuf *, uint16_t type, ovs_be16 value);
  95 void nl_msg_push_be32(struct ofpbuf *, uint16_t type, ovs_be32 value);
  96 void nl_msg_push_be64(struct ofpbuf *, uint16_t type, ovs_be64 value);
  97 void nl_msg_push_string(struct ofpbuf *, uint16_t type, const char *value);
  98
  99 /* Separating buffers into individual messages. */
 100 struct nlmsghdr *nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg);
 101
 102 /* Sizes of various attribute types, in bytes, including the attribute header
 103  * and padding.
 104  *
 105  * A minimum-size attribute is 4 bytes long: 4 bytes of header, no bytes of
 106  * payload, no padding.
 107  *
 108  * A maximum-size attribute is 65536 bytes long: 4 bytes of header, 65531 bytes
 109  * of payload, 1 byte of padding.  (Thus, NL_ATTR_SIZE() of a maximum length
 110  * attribute payload does not fit in 16 bits.) */
 111 #define NL_ATTR_SIZE(PAYLOAD_SIZE) (NLA_HDRLEN + NLA_ALIGN(PAYLOAD_SIZE))
 112 #define NL_A_U8_SIZE   NL_ATTR_SIZE(sizeof(uint8_t))
 113 #define NL_A_U16_SIZE  NL_ATTR_SIZE(sizeof(uint16_t))
 114 #define NL_A_U32_SIZE  NL_ATTR_SIZE(sizeof(uint32_t))
 115 #define NL_A_U64_SIZE  NL_ATTR_SIZE(sizeof(uint64_t))
 116 #define NL_A_BE16_SIZE NL_ATTR_SIZE(sizeof(ovs_be16))
 117 #define NL_A_BE32_SIZE NL_ATTR_SIZE(sizeof(ovs_be32))
 118 #define NL_A_BE64_SIZE NL_ATTR_SIZE(sizeof(ovs_be64))
 119 #define NL_A_FLAG_SIZE NL_ATTR_SIZE(0)
 120 #define NL_A_IPV6_SIZE NL_ATTR_SIZE(sizeof(struct in6_addr))
 121
 122 bool nl_attr_oversized(size_t payload_size);
 123 \f
 124 /* Netlink attribute types. */
 125 enum nl_attr_type
 126 {
 127     NL_A_NO_ATTR = 0,
 128     NL_A_UNSPEC,
 129     NL_A_U8,
 130     NL_A_U16,
 131     NL_A_BE16 = NL_A_U16,
 132     NL_A_U32,
 133     NL_A_BE32 = NL_A_U32,
 134     NL_A_U64,
 135     NL_A_BE64 = NL_A_U64,
 136     NL_A_STRING,
 137     NL_A_FLAG,
 138     NL_A_IPV6,
 139     NL_A_NESTED,
 140     N_NL_ATTR_TYPES
 141 };
 142
 143 /* Netlink attribute iteration. */
 144 static inline struct nlattr *
 145 nl_attr_next(const struct nlattr *nla)
 146 {
 147     return (void *) ((uint8_t *) nla + NLA_ALIGN(nla->nla_len));
 148 }
 149
 150 static inline bool
 151 nl_attr_is_valid(const struct nlattr *nla, size_t maxlen)
 152 {
 153     return (maxlen >= sizeof *nla
 154             && nla->nla_len >= sizeof *nla
 155             && nla->nla_len <= maxlen);
 156 }
 157
 158 static inline size_t
 159 nl_attr_len_pad(const struct nlattr *nla, size_t maxlen)
 160 {
 161     size_t len = NLA_ALIGN(nla->nla_len);
 162
 163     return len <= maxlen ? len : nla->nla_len;
 164 }
 165
 166 /* This macro is careful to check for attributes with bad lengths. */
 167 #define NL_ATTR_FOR_EACH(ITER, LEFT, ATTRS, ATTRS_LEN)                  \
 168     for ((ITER) = (ATTRS), (LEFT) = (ATTRS_LEN);                        \
 169          nl_attr_is_valid(ITER, LEFT);                                  \
 170          (LEFT) -= nl_attr_len_pad(ITER, LEFT), (ITER) = nl_attr_next(ITER))
 171
 172
 173 /* This macro does not check for attributes with bad lengths.  It should only
 174  * be used with messages from trusted sources or with messages that have
 175  * already been validated (e.g. with NL_ATTR_FOR_EACH).  */
 176 #define NL_ATTR_FOR_EACH_UNSAFE(ITER, LEFT, ATTRS, ATTRS_LEN)           \
 177     for ((ITER) = (ATTRS), (LEFT) = (ATTRS_LEN);                        \
 178          (LEFT) > 0;                                                    \
 179          (LEFT) -= nl_attr_len_pad(ITER, LEFT), (ITER) = nl_attr_next(ITER))
 180
 181 /* These variants are convenient for iterating nested attributes. */
 182 #define NL_NESTED_FOR_EACH(ITER, LEFT, A)                               \
 183     NL_ATTR_FOR_EACH(ITER, LEFT, nl_attr_get(A), nl_attr_get_size(A))
 184 #define NL_NESTED_FOR_EACH_UNSAFE(ITER, LEFT, A)                        \
 185     NL_ATTR_FOR_EACH_UNSAFE(ITER, LEFT, nl_attr_get(A), nl_attr_get_size(A))
 186
 187 /* Netlink attribute parsing. */
 188 int nl_attr_type(const struct nlattr *);
 189 const void *nl_attr_get(const struct nlattr *);
 190 size_t nl_attr_get_size(const struct nlattr *);
 191 const void *nl_attr_get_unspec(const struct nlattr *, size_t size);
 192 bool nl_attr_get_flag(const struct nlattr *);
 193 uint8_t nl_attr_get_u8(const struct nlattr *);
 194 uint16_t nl_attr_get_u16(const struct nlattr *);
 195 uint32_t nl_attr_get_u32(const struct nlattr *);
 196 uint64_t nl_attr_get_u64(const struct nlattr *);
 197 ovs_be16 nl_attr_get_be16(const struct nlattr *);
 198 ovs_be32 nl_attr_get_be32(const struct nlattr *);
 199 ovs_be64 nl_attr_get_be64(const struct nlattr *);
 200 struct in6_addr nl_attr_get_in6_addr(const struct nlattr *nla);
 201 odp_port_t nl_attr_get_odp_port(const struct nlattr *);
 202 const char *nl_attr_get_string(const struct nlattr *);
 203 void nl_attr_get_nested(const struct nlattr *, struct ofpbuf *);
 204
 205 /* Netlink attribute policy.
 206  *
 207  * Specifies how to parse a single attribute from a Netlink message payload.
 208  */
 209 struct nl_policy
 210 {
 211     enum nl_attr_type type;
 212     size_t min_len, max_len;
 213     bool optional;
 214 };
 215
 216 #define NL_POLICY_FOR(TYPE) \
 217     .type = NL_A_UNSPEC, .min_len = sizeof(TYPE), .max_len = sizeof(TYPE)
 218
 219 bool nl_attr_validate(const struct nlattr *, const struct nl_policy *);
 220
 221 bool nl_policy_parse(const struct ofpbuf *, size_t offset,
 222                      const struct nl_policy[],
 223                      struct nlattr *[], size_t n_attrs);
 224 bool nl_parse_nested(const struct nlattr *, const struct nl_policy[],
 225                      struct nlattr *[], size_t n_attrs);
 226
 227 const struct nlattr *nl_attr_find(const struct ofpbuf *, size_t hdr_len,
 228                                   uint16_t type);
 229 const struct nlattr *nl_attr_find_nested(const struct nlattr *, uint16_t type);
 230 const struct nlattr *nl_attr_find__(const struct nlattr *attrs, size_t size,
 231                                     uint16_t type);
 232
 233 #endif /* netlink.h */