lib/netlink.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   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 <stdbool.h>
  35 #include <stddef.h>
  36 #include <stdint.h>
  37
  38 struct ofpbuf;
  39 struct nlattr;
  40
  41 /* Accessing headers and data. */
  42 struct nlmsghdr *nl_msg_nlmsghdr(const struct ofpbuf *);
  43 struct genlmsghdr *nl_msg_genlmsghdr(const struct ofpbuf *);
  44 bool nl_msg_nlmsgerr(const struct ofpbuf *, int *error);
  45 void nl_msg_reserve(struct ofpbuf *, size_t);
  46
  47 /* Appending headers and raw data. */
  48 void nl_msg_put_nlmsghdr(struct ofpbuf *, size_t expected_payload,
  49                          uint32_t type, uint32_t flags);
  50 void nl_msg_put_genlmsghdr(struct ofpbuf *, size_t expected_payload,
  51                            int family, uint32_t flags,
  52                            uint8_t cmd, uint8_t version);
  53 void nl_msg_put(struct ofpbuf *, const void *, size_t);
  54 void *nl_msg_put_uninit(struct ofpbuf *, size_t);
  55
  56 /* Appending attributes. */
  57 void *nl_msg_put_unspec_uninit(struct ofpbuf *, uint16_t type, size_t);
  58 void nl_msg_put_unspec(struct ofpbuf *, uint16_t type, const void *, size_t);
  59 void nl_msg_put_flag(struct ofpbuf *, uint16_t type);
  60 void nl_msg_put_u8(struct ofpbuf *, uint16_t type, uint8_t value);
  61 void nl_msg_put_u16(struct ofpbuf *, uint16_t type, uint16_t value);
  62 void nl_msg_put_u32(struct ofpbuf *, uint16_t type, uint32_t value);
  63 void nl_msg_put_u64(struct ofpbuf *, uint16_t type, uint64_t value);
  64 void nl_msg_put_be16(struct ofpbuf *, uint16_t type, ovs_be16 value);
  65 void nl_msg_put_be32(struct ofpbuf *, uint16_t type, ovs_be32 value);
  66 void nl_msg_put_be64(struct ofpbuf *, uint16_t type, ovs_be64 value);
  67 void nl_msg_put_string(struct ofpbuf *, uint16_t type, const char *value);
  68
  69 size_t nl_msg_start_nested(struct ofpbuf *, uint16_t type);
  70 void nl_msg_end_nested(struct ofpbuf *, size_t offset);
  71 void nl_msg_put_nested(struct ofpbuf *, uint16_t type,
  72                        const void *data, size_t size);
  73
  74 /* Separating buffers into individual messages. */
  75 struct nlmsghdr *nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg);
  76 \f
  77 /* Netlink attribute types. */
  78 enum nl_attr_type
  79 {
  80     NL_A_NO_ATTR = 0,
  81     NL_A_UNSPEC,
  82     NL_A_U8,
  83     NL_A_U16,
  84     NL_A_U32,
  85     NL_A_U64,
  86     NL_A_STRING,
  87     NL_A_FLAG,
  88     NL_A_NESTED,
  89     N_NL_ATTR_TYPES
  90 };
  91
  92 /* Netlink attribute parsing. */
  93 const void *nl_attr_get(const struct nlattr *);
  94 size_t nl_attr_get_size(const struct nlattr *);
  95 const void *nl_attr_get_unspec(const struct nlattr *, size_t size);
  96 bool nl_attr_get_flag(const struct nlattr *);
  97 uint8_t nl_attr_get_u8(const struct nlattr *);
  98 uint16_t nl_attr_get_u16(const struct nlattr *);
  99 uint32_t nl_attr_get_u32(const struct nlattr *);
 100 uint64_t nl_attr_get_u64(const struct nlattr *);
 101 ovs_be16 nl_attr_get_be16(const struct nlattr *);
 102 ovs_be32 nl_attr_get_be32(const struct nlattr *);
 103 ovs_be64 nl_attr_get_be64(const struct nlattr *);
 104 const char *nl_attr_get_string(const struct nlattr *);
 105 void nl_attr_get_nested(const struct nlattr *, struct ofpbuf *);
 106
 107 /* Netlink attribute policy.
 108  *
 109  * Specifies how to parse a single attribute from a Netlink message payload.
 110  */
 111 struct nl_policy
 112 {
 113     enum nl_attr_type type;
 114     size_t min_len, max_len;
 115     bool optional;
 116 };
 117
 118 bool nl_policy_parse(const struct ofpbuf *, size_t offset,
 119                      const struct nl_policy[],
 120                      struct nlattr *[], size_t n_attrs);
 121 bool nl_parse_nested(const struct nlattr *, const struct nl_policy[],
 122                      struct nlattr *[], size_t n_attrs);
 123
 124 #endif /* netlink.h */