#keywords programming,netlink,socket,hotplug,ipsec,kernel,linux
#title Netlink socket에 대하여
[wiki:Home 대문] / [wiki:CategoryProgramming 프로그래밍] / [wiki:AboutNetLinkSocket Netlink socket에 대하여]
----
== [wiki:AboutNetLinkSocket Netlink socket에 대하여] ==
 * 작성자
  조재혁([mailto:minzkn@minzkn.com])

 * 고친과정
  2017년 1월 9일 : 처음씀

[[TableOfContents]]
=== 개요 ===
[[attachment:netlink.png]]

 Netlink 는 Kernel과 User space간 원활한 정보교류를 위한 비교적 유연한 통신 방식입니다.

 본 내용을 이해하기 위해서 다음의 Linux kernel header 를 먼저 열어보시고 함께 보시면 좋습니다.
  * "<linux/netlink.h>"
   {{{#!folding
   {{{#!enscript c
#define NETLINK_<XXX> ...
#define NLM_F_<XXX> ...

#define NLMSG_ALIGNTO   4U
#define NLMSG_ALIGN(len) ( ((len)+NLMSG_ALIGNTO-1) & ~(NLMSG_ALIGNTO-1) )
#define NLMSG_HDRLEN     ((int) NLMSG_ALIGN(sizeof(struct nlmsghdr)))
#define NLMSG_LENGTH(len) ((len) + NLMSG_HDRLEN)
#define NLMSG_SPACE(len) NLMSG_ALIGN(NLMSG_LENGTH(len))
#define NLMSG_DATA(nlh)  ((void*)(((char*)nlh) + NLMSG_LENGTH(0)))
#define NLMSG_NEXT(nlh,len)      ((len) -= NLMSG_ALIGN((nlh)->nlmsg_len), \
                                  (struct nlmsghdr*)(((char*)(nlh)) + NLMSG_ALIGN((nlh)->nlmsg_len)))
#define NLMSG_OK(nlh,len) ((len) >= (int)sizeof(struct nlmsghdr) && \
                           (nlh)->nlmsg_len >= sizeof(struct nlmsghdr) && \
                           (nlh)->nlmsg_len <= (len))
#define NLMSG_PAYLOAD(nlh,len) ((nlh)->nlmsg_len - NLMSG_SPACE((len)))

#define NLMSG_NOOP              0x1     /* Nothing.             */
#define NLMSG_ERROR             0x2     /* Error                */
#define NLMSG_DONE              0x3     /* End of a dump        */
#define NLMSG_OVERRUN           0x4     /* Data lost            */

#define NLMSG_MIN_TYPE          0x10    /* < 0x10: reserved control messages */

#define NLA_ALIGNTO             4
#define NLA_ALIGN(len)          (((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1))
#define NLA_HDRLEN              ((int) NLA_ALIGN(sizeof(struct nlattr)))

struct sockaddr_nl { ... };
struct nlmsghdr { ... };
struct nlattr { ... };
}}}
}}}
  * "<linux/genetlink.h>"
   {{{#!folding
   {{{#!enscript c
#define GENL_HDRLEN     NLMSG_ALIGN(sizeof(struct genlmsghdr))
#define GENL_ID_CTRL            NLMSG_MIN_TYPE

enum {
...
        CTRL_ATTR_FAMILY_ID,
        CTRL_ATTR_FAMILY_NAME,
...
};

struct genlmsghdr { ... };
}}}
}}}
  * "<linux/rtnetlink.h>"
   {{{#!folding
   {{{#!enscript c
#define RTA_ALIGNTO     4U
#define RTA_ALIGN(len) ( ((len)+RTA_ALIGNTO-1) & ~(RTA_ALIGNTO-1) )
#define RTA_OK(rta,len) ((len) >= (int)sizeof(struct rtattr) && \
                         (rta)->rta_len >= sizeof(struct rtattr) && \
                         (rta)->rta_len <= (len))
#define RTA_NEXT(rta,attrlen)   ((attrlen) -= RTA_ALIGN((rta)->rta_len), \
                                 (struct rtattr*)(((char*)(rta)) + RTA_ALIGN((rta)->rta_len)))
#define RTA_LENGTH(len) (RTA_ALIGN(sizeof(struct rtattr)) + (len))
#define RTA_SPACE(len)  RTA_ALIGN(RTA_LENGTH(len))
#define RTA_DATA(rta)   ((void*)(((char*)(rta)) + RTA_LENGTH(0)))
#define RTA_PAYLOAD(rta) ((int)((rta)->rta_len) - RTA_LENGTH(0))

struct rtattr { ... };
struct rtmsg { ... };
}}}
}}}
  * "<linux/if_addr.h>"
  * "<linux/if_link.h>"
  * "<linux/netconf.h>"
  * "<linux/neighbour.h>"
  * "<linux/xfrm.h>" : (Transform) IPSec VPN에 관련한 Netlink 정의

 * 예제소스
  * IPSsec 관련 모니터링 예제소스 : [attachment:netlink_ipsec_monitor-source.tar.gz]
  * Hotplug(udev) 장치 Event 예제소스 : [attachment:mzudev-source.tar.gz]
  * Network interface 및 routing 정보 질의 예제소스 : [attachment:netlink_rtnetlink_monitor-source-20180628.tar.gz]
  * 초단간 Process 별 I/O(Read/Write) 누적량 확인 예제소스 : [attachment:netlink_iotop-source-~20190319.tar.gz]
  * => 보다 정확한 Netlink message 구현은 iproute2 소스 및 iotop 소스를 참고하실 것을 추천합니다.
=== netlink message format ===
 기본적으로 Netlink message는 하나 이상을 연속으로 붙여 하나의 요청(Request) 또는 응답(Response) 단위로 묶어 전송구현합니다.
  {{{#!plain

 +----------------------+----------------------+----------------------+----------------------+ ~ ~ ~ ~ ~ +----------------------+
 |  Netlink messaeg #1  |  Netlink messaeg #2  |  Netlink messaeg #3  |  Netlink messaeg #4  |    ...    |  Netlink messaeg #n  |
 | (Header+Payload+Pad) | (Header+Payload+Pad) | (Header+Payload+Pad) | (Header+Payload+Pad) |           | (Header+Payload+Pad) |
 +----------------------+----------------------+----------------------+----------------------+ ~ ~ ~ ~ ~ +----------------------+

 <--------------------------------------------------- Request OR Response packet ----------------------------------------------->

}}}

 하나의 Netlink message의 Header와 Payload는 각각 정렬(Align)된 형태를 맞추기 위해서 Padding 을 포함할 수 있습니다. (정렬의 크기는 "<linux/netlink.h>" kernel header에 정의된 NLMSG_ALIGNTO 정의를 기준으로 하며 NLMSG_ALIGN macro 함수를 사용하여 계산할 수 있습니다.)

 * Netlink message format
  |Netlink message format|<bgcolor="gray">  '''0'''  ||<bgcolor="gray">  '''1'''  ||<bgcolor="gray">  '''2'''  ||<bgcolor="gray">  '''3'''  ||<bgcolor="gray">  '''4'''  ||<bgcolor="gray">  '''5'''  ||<bgcolor="gray">  '''6'''  ||<bgcolor="gray">  '''7'''  ||<bgcolor="gray">  '''8'''  ||<bgcolor="gray">  '''9'''  ||<bgcolor="gray">  '''10'''  ||<bgcolor="gray">  '''11'''  ||<bgcolor="gray">  '''12'''  ||<bgcolor="gray">  '''13'''  ||<bgcolor="gray">  '''14'''  ||<bgcolor="gray">  '''15'''  ||<bgcolor="gray">  '''16'''  ||<bgcolor="gray">  '''17'''  ||<bgcolor="gray">  '''18'''  ||<bgcolor="gray">  '''19'''  ||<bgcolor="gray">  '''20'''  ||<bgcolor="gray">  '''21'''  ||<bgcolor="gray">  '''22'''  ||<bgcolor="gray">  '''23'''  ||<bgcolor="gray">  '''24'''  ||<bgcolor="gray">  '''25'''  ||<bgcolor="gray">  '''26'''  ||<bgcolor="gray">  '''27'''  ||<bgcolor="gray">  '''28'''  ||<bgcolor="gray">  '''29'''  ||<bgcolor="gray">  '''30'''  ||<bgcolor="gray">  '''31'''  ||||<bgcolor="orange"> '''Description''' ||
  ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  32bit Length (Header를 포함한 message 크기)  ||<|4><bgcolor="yellow">  ↑↓16 bytes NLMSG_HDRLEN[[BR]](struct nlmsghdr)  ||<|5><bgcolor="yellow">  ↑↓Netlink message[[BR]](nlmsghdr.nlmsg_len)  ||
  ||||||||||||||||||||||||||||||||  16-bit Type (Message content)  ||||||||||||||||||||||||||||||||  16-bit Flags (Additional flags)  ||
  ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  32bit Sequence Number  ||
  ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  32bit Process ID (PID, Sending process port ID)  ||
  ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||  Payload (Variable data)[[BR]]data_ptr = NLMSG_DATA(nlmsghdr)  ||<bgcolor="yellow">  ↑↓(nlmsghdr.nlmsg_len - NLMSG_HDRLEN)  ||

 * Netlink message overview
  {{{#!plain
  <----- NLMSG_HDRLEN ------> <-------- Payload-Len -------->
 +---------------------+- - -+- - - - - - - - - - - - - - - -+ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 |        Header       | Pad |            Payload            | ... (Next netlink message) ...
 |  (struct nlmsghdr)  | ing | Specific data + [attribute..] |
 +---------------------+- - -+- - - - - - - - - - - - - - - -+ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 ↑ nlmsghdr                  ↑ NLMSG_DATA(&nlmsghdr)         ↑ NLMSG_NEXT(&nlmsghdr)
  <------------------ nlmsghdr->nlmsg_len ------------------>
  <------------------ NLMSG_LENGTH(Payload-Len) ------------>

  Payload의 선두부분은 nlmsg_type에 따른 고유 구조체(Specific data) 형식이 올 수 있으며 NLMSG_ALIGN(sizeof(Specific data)) 정렬 후 그 다음에 attribute로 구성되는게 일반적입니다.
}}}

 * Netlink attribute overview (Netlink message payload 내에서 Specific data 뒷부분에 선택적으로 추가됨)
  {{{#!plain
  <------- NLA_HDRLEN ------> <-- NLA_ALIGN(payload)-->
 +---------------------+- - -+- - - - - - - - - -+- - -+ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 |        Header       | Pad |     Payload       | Pad | ... (Next attribute) ...
 |   (struct nlattr)   | ing |                   | ing |
 +---------------------+- - -+- - - - - - - - - -+- - -+ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
 ↑ nlattr
  <-------------- nlattr->nla_len -------------->


 nla_type (16 bits)
 +---+---+-------------------------------+
 | N | O | Attribute Type                |
 +---+---+-------------------------------+
 N := Carries nested attributes
 O := Payload stored in network byte order
 Note: The N and O flag are mutually exclusive.
}}}

 * netlink header struct
  {{{#!enscript c
 struct nlmsghdr {
     uint32_t nlmsg_len;      /* Header를 포함한 Netlink message 크기 */
     uint16_t nlmsg_type;     /* Message content */
     uint16_t nlmsg_flags;    /* Additional flags */
     uint32_t nlmsg_seq;      /* Sequence number */
     uint32_t nlmsg_pid;      /* Sending process port ID */
 };
}}}

 * netlink attribute header struct
  {{{#!enscript c
 struct nlattr {
     uint16_t nla_len; /* Header를 포함한 attribute 크기 */
     uint16_t nla_type; /* Attribute type */
 };
}}}

=== Generic Netlink message Overview ===
 {{{#!plain
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                Netlink message header (nlmsghdr)              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |           Generic Netlink message header (genlmsghdr)         |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             Optional user specific message header             |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |           Optional Generic Netlink message payload            |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
}}}

 "iotop" 명령어가 task 상태에 대한 모니터링을 위한 구현을 위해서 Generic Netlink를 사용하는 대표적 사용예입니다.
=== 구현사항에 대한 간략한 골격구조 설명 ===
 1. Netlink socket을 XFRM쪽으로 open
  {{{#!enscript c
s_socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_XFRM /* 6 - ipsec */);
}}}

 2. XFRM모듈쪽의 어떤 Group 과 통신할지를 binding
  {{{#!enscript c
__u32 s_nl_groups;
struct sockaddr_nl s_sockaddr_nl;

s_nl_groups |= XFRMNLGRP_ACQUIRE;
s_nl_groups |= XFRMNLGRP_EXPIRE;
s_nl_groups |= XFRMNLGRP_SA;
s_nl_groups |= XFRMNLGRP_POLICY;
s_nl_groups |= XFRMNLGRP_AEVENTS;
s_nl_groups |= XFRMNLGRP_REPORT;
s_nl_groups |= XFRMNLGRP_MIGRATE;
s_nl_groups |= XFRMNLGRP_MAPPING;

s_sockaddr_nl.nl_family = AF_NETLINK;
s_sockaddr_nl.nl_pad = (unsigned short)0u;
s_sockaddr_nl.nl_pid = (pid_t)0;
s_sockaddr_nl.nl_groups = s_nl_groups; /* Multicast groups mask */

bind(s_socket, (const struct sockaddr *)(&s_sockaddr_nl), (socklen_t)sizeof(s_sockaddr_nl));
}}}

 3. netlink socket으로부터 Netlink protocol RAW 수신
  {{{#!enscript c
socklen_t s_socklen;

s_socklen = (socklen_t)sizeof(s_sockaddr_nl);
s_recv_bytes = recvfrom(
    s_socket,
    s_buffer,
    s_buffer_size,
    MSG_NOSIGNAL,
    (struct sockaddr *)(&s_sockaddr_nl),
    (socklen_t *)(&s_socklen)
);
}}}

 4. 수신된 Netlink protocol RAW data에서 Netlink header 를 통해서 각 요소별 분리
  {{{#!enscript c
size_t s_msg_size;
struct nlmsghdr *s_nlmsghdr;
size_t s_payload_size;
void *s_payload;

s_msg_size = (size_t)s_recv_bytes;
for(s_nlmsghdr = (struct nlmsghdr *)s_buffer;(s_is_break == 0) && NLMSG_OK(s_nlmsghdr, s_msg_size);s_nlmsghdr = NLMSG_NEXT(s_nlmsghdr, s_msg_size)) {            /* Netlink 수신패킷 하나에 여러개의 Netlink header가 탑재될 수 있는데 이를 각 Header 단위로 분리하는 Loop */
    s_payload_size = (size_t)NLMSG_PAYLOAD(s_nlmsghdr, 0); /* Header 내의 실제 Data 크기 */
    s_payload = NLMSG_DATA(s_nlmsghdr); /* Header 내의 실제 Data 위치 포인터 */

    switch(s_nlmsghdr->nlmsg_type) { /* 각 메세지의 종류별로 다른 파싱구조를 가지고 있으므로 커널을 참조하여 해당 부분을 파싱해야 합니다. */
        .....
    }
}
}}}
=== 실제 VPN 장비에서 VPN연결과정에서 본 예제프로그램으로 Netlink 통신을 수신하여 파싱된 내용을 모니터링한 콘솔내용 ===
{{{#!folding 내용을 보시려면 여기를 클릭해주세요.
* "XFRM_MSG_DELSA" (type=17[0011H], flags=0000H[<NONE FLAGS>], seq=1834996, pid=3534, len=680, payload_size=664, remain=680/680)
  daddr:
    IPv4: 10.21.1.63
  spi: 3233923735[C0C1C297H]
  family: 2[0002H] - INET
  proto: 50[32H] - esp
* "XFRM_MSG_DELSA" (type=17[0011H], flags=0000H[<NONE FLAGS>], seq=1834997, pid=3534, len=680, payload_size=664, remain=680/680)
  daddr:
    IPv4: 10.21.1.54
  spi: 132448353[07E50061H]
  family: 2[0002H] - INET
  proto: 50[32H] - esp
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1834998, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1834999, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835000, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835001, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835002, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835003, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELSA" (type=17[0011H], flags=0000H[<NONE FLAGS>], seq=1835006, pid=3534, len=680, payload_size=664, remain=680/680)
  daddr:
    IPv4: 10.21.1.64
  spi: 3274289891[C329B2E3H]
  family: 2[0002H] - INET
  proto: 50[32H] - esp
* "XFRM_MSG_DELSA" (type=17[0011H], flags=0000H[<NONE FLAGS>], seq=1835007, pid=3534, len=680, payload_size=664, remain=680/680)
  daddr:
    IPv4: 10.21.1.54
  spi: 132579426[07E70062H]
  family: 2[0002H] - INET
  proto: 50[32H] - esp
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835008, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835009, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835010, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835011, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835012, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835013, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELSA" (type=17[0011H], flags=0000H[<NONE FLAGS>], seq=1835016, pid=3534, len=680, payload_size=664, remain=680/680)
  daddr:
    IPv4: 10.21.1.65
  spi: 3366946281[C8AF85E9H]
  family: 2[0002H] - INET
  proto: 50[32H] - esp
* "XFRM_MSG_DELSA" (type=17[0011H], flags=0000H[<NONE FLAGS>], seq=1835017, pid=3534, len=680, payload_size=664, remain=680/680)
  daddr:
    IPv4: 10.21.1.54
  spi: 132710499[07E90063H]
  family: 2[0002H] - INET
  proto: 50[32H] - esp
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835018, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835019, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835020, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835021, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835022, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_DELPOLICY" (type=20[0014H], flags=0000H[<NONE FLAGS>], seq=1835023, pid=3534, len=348, payload_size=332, remain=348/348)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  index: 0
  dir: 0
* "XFRM_MSG_UPDSA" (type=26[001AH], flags=0000H[<NONE FLAGS>], seq=1835027, pid=3534, len=652, payload_size=636, remain=652/652)
  selector:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    saddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  id:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    spi: 0[00000000H]
    proto: 0[00H] - ip
  saddr:
    IPv? (UNSPEC): family=0[0000H]
      IPv4: 0.0.0.0
      IPv6: ::a15:140:0:0
      hex dump:
        00000000 00 00 00 00 00 00 00 00 | 0A 15 01 40 00 00 00 00 [...........@....]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/216245484232
    soft_packet_limit/hard_packet_limit: 906040586/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifet[533720.015428] kjournald starting.  Commit interval 5 seconds
ime_cur:
    by[533720.036463] EXT3-fs (sda2): warning: maximal mount count reached, running e2fsck is recommended
tes: 28343
    [533720.067021] EXT3-fs (sda2): using internal journal
packets: 28800
[533720.085621] EXT3-fs (sda2): mounted filesystem with ordered data mode
    add_time: 0
    use_time: 0
  stats:
    replay_window/replay: 0/0
    integrity_failed: 0[00000000H]
  seq: 0
  reqid: 1483947834
  family: 0[0000H] - UNSPEC
  mode: 0[00H] - TRANSPORT
  replay_window: 0[00H]
  flags: 0[00H] - <NONE FLAGS>
* "XFRM_MSG_NEWSA" (type=16[0010H], flags=0000H[<NONE FLAGS>], seq=1835028, pid=3534, len=652, payload_size=636, remain=652/652)
  selector:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    saddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  id:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    spi: 0[00000000H]
    proto: 0[00H] - ip
  saddr:
    IPv? (UNSPEC): family=0[0000H]
      IPv4: 0.0.0.0
      IPv6: ::a15:136:0:0
      hex dump:
        00000000 00 00 00 00 00 00 00 00 | 0A 15 01 36 00 00 00 00 [...........6....]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/216426146567
    soft_packet_limit/hard_packet_limit: 1073812746/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 28381
    packets: 28800
    add_time: 0
    use_time: 0
  stats:
    replay_window/replay: 0/0
    integrity_failed: 0[00000000H]
  seq: 0
  reqid: 1483947834
  family: 0[0000H] - UNSPEC
  mode: 0[00H] - TRANSPORT
  replay_window: 0[00H]
  flags: 0[00H] - <NONE FLAGS>
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835029, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835030, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835031, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835032, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835033, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mas[533721.639703] [2017-01-09 16:43:59] Finished reinitializing the system config.
k: 0[0000H]/0[00[533721.665369] -----------------------------------------------------------------------------------
[533721.665369]
00H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835034, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.17.0.0 (ac11::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDSA" (type=26[001AH], flags=0000H[<NONE FLAGS>], seq=1835035, pid=3534, len=652, payload_size=636, remain=652/652)
  selector:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    saddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  id:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    spi: 0[00000000H]
    proto: 0[00H] - ip
  saddr:
    IPv? (UNSPEC): family=0[0000H]
      IPv4: 0.0.0.0
      IPv6: ::a15:13f:0:0
      hex dump:
        00000000 00 00 00 00 00 00 00 00 | 0A 15 01 3F 00 00 00 00 [...........?....]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/217379960769
    soft_packet_limit/hard_packet_limit: 906040586/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 28334
    packets: 28800
    add_time: 0
    use_time: 0
  stats:
    replay_window/replay: 0/0
    integrity_failed: 0[00000000H]
  seq: 0
  reqid: 1483947834
  family: 0[0000H] - UNSPEC
  mode: 0[00H] - TRANSPORT
  replay_window: 0[00H]
  flags: 0[00H] - <NONE FLAGS>
* "XFRM_MSG_NEWSA" (type=16[0010H], flags=0000H[<NONE FLAGS>], seq=1835036, pid=3534, len=652, payload_size=636, remain=652/652)
  selector:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    saddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  id:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    spi: 0[00000000H]
    proto: 0[00H] - ip
  saddr:
    IPv? (UNSPEC): family=0[0000H]
      IPv4: 0.0.0.0
      IPv6: ::a15:136:0:0
      hex dump:
        00000000 00 00 00 00 00 00 00 00 | 0A 15 01 36 00 00 00 00 [...........6....]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/216442924295
    soft_packet_limit/hard_packet_limit: 1057035530/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 28248
    packets: 28800
    add_time: 0
    use_time: 0
  stats:
    replay_window/replay: 0/0
    integrity_failed: 0[00000000H]
  seq: 0
  reqid: 1483947834
  family: 0[0000H] - UNSPEC
  mode: 0[00H] - TRANSPORT
  replay_window: 0[00H]
  flags: 0[00H] - <NONE FLAGS>
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835037, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835038, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835039, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835040, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835041, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835042, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.16.0.0 (ac10::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDSA" (type=26[001AH], flags=0000H[<NONE FLAGS>], seq=1835043, pid=3534, len=652, payload_size=636, remain=652/652)
  selector:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    saddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  id:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    spi: 0[00000000H]
    proto: 0[00H] - ip
  saddr:
    IPv? (UNSPEC): family=0[0000H]
      IPv4: 0.0.0.0
      IPv6: ::a15:141:0:0
      hex dump:
        00000000 00 00 00 00 00 00 00 00 | 0A 15 01 41 00 00 00 00 [...........A....]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/215087206849
    soft_packet_limit/hard_packet_limit: 906040586/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 28411
    packets: 28800
    add_time: 0
    use_time: 0
  stats:
    replay_window/replay: 0/0
    integrity_failed: 0[00000000H]
  seq: 0
  reqid: 1483947834
  family: 0[0000H] - UNSPEC
  mode: 0[00H] - TRANSPORT
  replay_window: 0[00H]
  flags: 0[00H] - <NONE FLAGS>
* "XFRM_MSG_NEWSA" (type=16[0010H], flags=0000H[<NONE FLAGS>], seq=1835044, pid=3534, len=652, payload_size=636, remain=652/652)
  selector:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    saddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  id:
    daddr:
      IPv4 (UNSPECIFIED): 0.0.0.0 (::)
    spi: 0[00000000H]
    proto: 0[00H] - ip
  saddr:
    IPv? (UNSPEC): family=0[0000H]
      IPv4: 0.0.0.0
      IPv6: ::a15:136:0:0
      hex dump:
        00000000 00 00 00 00 00 00 00 00 | 0A 15 01 36 00 00 00 00 [...........6....]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/216459702023
    soft_packet_limit/hard_packet_limit: 1090589962/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 28324
    packets: 28800
    add_time: 0
    use_time: 0
  stats:
    replay_window/replay: 0/0
    integrity_failed: 0[00000000H]
  seq: 0
  reqid: 1483947834
  family: 0[0000H] - UNSPEC
  mode: 0[00H] - TRANSPORT
  replay_window: 0[00H]
  flags: 0[00H] - <NONE FLAGS>
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835045, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835046, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_NEWPOLICY" (type=19[0013H], flags=0000H[<NONE FLAGS>], seq=1835047, pid=3534, len=248, payload_size=232, remain=248/248)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835048, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    saddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 17695265390592/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835049, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
* "XFRM_MSG_UPDPOLICY" (type=25[0019H], flags=0000H[<NONE FLAGS>], seq=1835050, pid=3534, len=316, payload_size=300, remain=316/316)
  selector:
    daddr:
      IPv4 (v4 or v6 ?): 172.18.0.0 (ac12::)
    saddr:
      IPv4 (v4 or v6 ?): 192.168.0.0 (c0a8::)
    dport/mask: 0[0000H]/0[0000H]
    sport/mask: 0[0000H]/0[0000H]
    family: 0[0000H] - UNSPEC
    prefixlen_d: 0
    prefixlen_s: 0
    proto: 0[00H] - ip
    ifindex: 0
    user: 0[00H]
  lifetime_cfg:
    soft_byte_limit/hard_byte_limit: 0/0
    soft_packet_limit/hard_packet_limit: 26456998674432/0
    soft_add_expires_seconds/hard_add_expires_seconds: 18446744073709551615/18446744073709551615
    soft_use_expires_seconds/hard_use_expires_seconds: 18446744073709551615/18446744073709551615
  lifetime_cur:
    bytes: 0
    packets: 0
    add_time: 0
    use_time: 0
  priority: 0
  index: 0
  dir: 0
  action: 0 - POLICY_ALLOW
  flags: 0[00H] - <NONE FLAGS>
  share: 0[00H]
}}}
=== Netlink 를 가공하기 위한 함수 예시 ===
 * Netlink를 다루기 위한 기본 macro 를 포함하기 위한 include
 {{{#!enscript c
#include <linux/netlink.h>
#include <linux/genetlink.h>
}}}
 * Netlink message (NLMSG) build 함수
 {{{#!enscript c
size_t hwport_generate_netlink_message(void *s_buffer, size_t s_buffer_size, unsigned int s_nlmsg_type, unsigned int s_nlmsg_flags, unsigned int s_nlmsg_seq, unsigned int s_nlmsg_pid, const void *s_payload, size_t s_payload_size)
{
        int s_aligned_payload_size;

        struct nlmsghdr *s_nlmsghdr;
        void *s_payload_ptr;

        s_aligned_payload_size = (int)NLMSG_ALIGN((uint32_t)s_payload_size);
        if (s_buffer_size < ((size_t)NLMSG_LENGTH(s_aligned_payload_size))) {
                return((size_t)0u);
        }

        s_nlmsghdr = (struct nlmsghdr *)memset(s_buffer, 0, sizeof(struct nlmsghdr));
        s_nlmsghdr->nlmsg_len = (uint32_t)NLMSG_LENGTH(s_aligned_payload_size);
        s_nlmsghdr->nlmsg_type = (uint16_t)s_nlmsg_type;
        s_nlmsghdr->nlmsg_flags = (uint16_t)s_nlmsg_flags;
        s_nlmsghdr->nlmsg_seq = (uint32_t)s_nlmsg_seq;
        s_nlmsghdr->nlmsg_pid = (uint32_t)s_nlmsg_pid;

        s_payload_ptr = (void *)NLMSG_DATA(s_nlmsghdr);
        if (s_payload_size > ((size_t)0u)) {
                if (s_payload == ((const void *)(NULL))) {
                        (void)memset(s_payload_ptr, 0, s_payload_size);
                }
                else {
                        (void)memcpy(s_payload_ptr, s_payload, s_payload_size);
                }
        }

        return((size_t)s_nlmsghdr->nlmsg_len);
}
}}}
 * Netlink attribute (NLA) build append 함수
 {{{#!enscript c
size_t hwport_append_netlink_attr(void *s_buffer, size_t s_buffer_size, unsigned int s_nla_type, const void *s_attr1, size_t s_attr1_size, const void *s_attr2, size_t s_attr2_size)
{
        struct nlmsghdr *s_nlmsghdr;
        struct nlattr *s_nlattr;
        size_t s_attr_size;
        void *s_attr_ptr;

        s_attr_size = s_attr1_size + s_attr2_size;

        s_nlmsghdr = (struct nlmsghdr *)s_buffer;
        if (s_buffer_size < ((size_t)(s_nlmsghdr->nlmsg_len + NLA_HDRLEN + NLA_ALIGN(s_attr_size)))) {
                return((size_t)0u);
        }

        s_nlattr = (struct nlattr *)(((uint8_t *)s_buffer) + s_nlmsghdr->nlmsg_len);
        s_nlattr->nla_len = (uint16_t)NLA_HDRLEN + s_attr_size;
        s_nlattr->nla_type = (uint16_t)s_nla_type;

        s_attr_ptr = (void *)(((uint8_t *)s_nlattr) + NLA_HDRLEN);
        if(s_attr1_size > ((size_t)0u)) {
                if(s_attr1 == ((const void *)0)) {
                        (void)memset((void *)s_attr_ptr, 0, s_attr1_size);
                }
                else if(((const void *)s_attr_ptr) != s_attr1) {
                        (void)memcpy((void *)s_attr_ptr, s_attr1, s_attr1_size);
                }

                s_attr_ptr = (void *)(((uint8_t *)s_attr_ptr) + s_attr1_size);
        }
        if(s_attr2_size > ((size_t)0u)) {
                if(s_attr2 == ((const void *)0)) {
                        (void)memset((void *)s_attr_ptr, 0, s_attr2_size);
                }
                else if(((const void *)s_attr_ptr) != s_attr2) {
                        (void)memcpy((void *)s_attr_ptr, s_attr2, s_attr2_size);
                }
        }

        s_nlmsghdr->nlmsg_len += (uint32_t)NLA_ALIGN(s_nlattr->nla_len);

        return((size_t)s_nlmsghdr->nlmsg_len);
}
}}}
 * Netlink message request 함수
 {{{#!enscript c
ssize_t hwport_request_generic_netlink(int s_socket, const void *s_data, size_t s_size, const struct sockaddr *s_sockaddr, socklen_t s_socklen)
{
        size_t s_sent_size;
        size_t s_want_size;
        ssize_t s_send_bytes;
        const uint8_t *s_uint8_ptr;
        struct sockaddr_nl s_sockaddr_nl;

        if (s_socket == (-1)) {
                errno = EINVAL;
                return((ssize_t)(-1));
        }

        if (s_sockaddr == ((struct sockaddr *)(NULL))) {
                s_socklen = (socklen_t)sizeof(s_sockaddr_nl);
                s_sockaddr = (const struct sockaddr *)memset((void *)(&s_sockaddr_nl), 0, sizeof(s_sockaddr_nl));
                s_sockaddr_nl.nl_family = AF_NETLINK;
                s_sockaddr_nl.nl_pid = 0; /* port ID */
                s_sockaddr_nl.nl_groups = 0; /* multicast groups mask */
        }

        s_sent_size = (size_t)0u;
        s_uint8_ptr = (const uint8_t *)s_data;
        while (s_sent_size < s_size) {
                s_want_size = s_size - s_sent_size;
                s_send_bytes = sendto(
                        s_socket,
                        (const void *)(&s_uint8_ptr[s_sent_size]),
                        s_want_size,
                        MSG_NOSIGNAL,
                        s_sockaddr,
                        s_socklen
                );
                if (s_send_bytes > ((ssize_t)0)) {
                        s_sent_size += (size_t)s_send_bytes;
                }
                else if((s_send_bytes == ((ssize_t)(-1))) && ((errno == EINTR) || (errno == EAGAIN))) {
                        continue;
                }
                else { /* error */
                        return(s_send_bytes);
                }
        }

        return((ssize_t)s_sent_size);
}
}}}
 * Netlink message response 함수
 {{{#!enscript c
ssize_t hwport_response_generic_netlink(int s_socket, void *s_data, size_t s_size, struct sockaddr *s_sockaddr, socklen_t *s_socklen_ptr)
{
        struct sockaddr_storage s_sockaddr_storage;
        socklen_t s_socklen;

        if (s_socket == (-1)) {
                errno = EINVAL;
                return((ssize_t)(-1));
        }

        if (s_sockaddr == ((struct sockaddr *)(NULL))) {
                s_sockaddr = (struct sockaddr *)memset((void *)(&s_sockaddr_storage), 0, sizeof(s_sockaddr_storage));
        }
        if (s_socklen_ptr == ((socklen_t *)(NULL))) {
                s_socklen = (socklen_t)sizeof(struct sockaddr_nl);
                s_socklen_ptr = (socklen_t *)(&s_socklen);
        }

        return(recvfrom(s_socket, s_data, s_size, MSG_NOSIGNAL, s_sockaddr, s_socklen_ptr));
}
}}}
 * Generic Netlink message 중에서 Family Name으로 요청하여 Family ID를 얻는 함수
 {{{#!enscript c
int hwport_get_family_id_by_name(int s_socket, const char *s_family_name)
{
        int s_family_id;
        size_t s_family_name_size;

        uint8_t s_buffer[ 4 << 10 ];
        size_t s_message_size;
        size_t s_offset;
        int s_is_break;
        struct nlmsghdr *s_nlmsghdr;
        struct genlmsghdr *s_genlmsghdr;
        struct nlattr *s_nlattr;

        ssize_t s_send_bytes;
        ssize_t s_recv_bytes;

        if (s_socket == (-1)) {
                errno = EINVAL;
                return(-1);
        }

        if (s_family_name == ((const char *)(NULL))) {
                errno = EINVAL;
                return(-1);
        }
        s_family_name_size = strlen(s_family_name);

        s_nlmsghdr = (struct nlmsghdr *)(&s_buffer[0]);
        s_message_size = hwport_generate_netlink_message(
                (void *)s_nlmsghdr,
                sizeof(s_buffer),
                (unsigned int)GENL_ID_CTRL, /* nlmsg_type */
                (unsigned int)NLM_F_REQUEST /* | NLM_F_ACK */, /* nlmsg_flags */
                0u, /* nlmsg_seq */
                (unsigned int)getpid(), /* nlmsg_pid */
                (const void *)(NULL), /* payload */
                sizeof(struct genlmsghdr)
        );
        if (s_message_size <= ((size_t)0u)) {
                errno = ENOMEM;
                return(-1);
        }

        s_genlmsghdr = (struct genlmsghdr *)memset((void *)NLMSG_DATA(s_nlmsghdr), 0, sizeof(struct genlmsghdr));
        s_genlmsghdr->cmd = CTRL_CMD_GETFAMILY; /* SeeAlso : CTRL_CMD_XXXX in "include/uapi/linux/genetlink.h" */
        s_genlmsghdr->version = 1 /* 해당 message 종류에 따른 VERSION을 넣어야 함 */;

        s_message_size = hwport_append_netlink_attr(
                (void *)s_nlmsghdr,
                sizeof(s_buffer),
                (unsigned int)CTRL_ATTR_FAMILY_NAME, /* nla_type */
                (const void *)s_family_name, /* attr1 */
                s_family_name_size + ((size_t)1u), /* attr1_size (family name 은 문자열 뒤의 nul terminate까지 포함한 길이여야 함) */
                (const void *)(NULL), /* attr2 */
                (size_t)0u /* attr2_size */
        );
        if (s_message_size <= ((size_t)0u)) {
                errno = ENOMEM;
                return(-1);
        }

        s_send_bytes = hwport_request_generic_netlink(
                s_socket,
                (const void *)s_nlmsghdr,
                s_message_size,
                (const struct sockaddr *)(NULL),
                (socklen_t)0
        );
        if (s_send_bytes <= ((ssize_t)0)) {
                return(-1);
        }

        s_recv_bytes = hwport_response_generic_netlink(
                s_socket,
                (void *)(&s_buffer[0]),
                sizeof(s_buffer),
                (struct sockaddr *)(NULL),
                (socklen_t *)(NULL)
        );
        if (s_recv_bytes <= ((ssize_t)0)) {
                return(-1);
        }

        s_family_id = (-1);

        s_is_break = 0;
        s_message_size = (size_t)s_recv_bytes;
        for (s_nlmsghdr = (struct nlmsghdr *)(&s_buffer[0]);(s_is_break == 0) && NLMSG_OK(s_nlmsghdr, s_message_size);s_nlmsghdr = NLMSG_NEXT(s_nlmsghdr, s_message_size)) {
                /* payload_size = (size_t)NLMSG_PAYLOAD(s_nlmsghdr, 0); */
                /* payload = NLMSG_DATA(s_nlmsghdr); */

                switch(s_nlmsghdr->nlmsg_type) {
                        case NLMSG_NOOP:
                                break;
                        case NLMSG_ERROR:
                                s_is_break = 1;
                                break;
                        case NLMSG_DONE:
                                s_is_break = 1;
                                break;
                        case NLMSG_OVERRUN:
                                s_is_break = 1;
                                break;
                        case GENL_ID_CTRL: /* NLMSG_MIN_TYPE */
                                s_genlmsghdr = (struct genlmsghdr *)NLMSG_DATA(s_nlmsghdr);
                                for (s_offset = (size_t)(NLMSG_HDRLEN + NLMSG_ALIGN(sizeof(struct genlmsghdr)));s_offset < s_nlmsghdr->nlmsg_len;) {
                                        if ((s_offset + ((size_t)NLA_HDRLEN)) > ((size_t)s_nlmsghdr->nlmsg_len)) {
                                                /* attibute header 만큼이 남지 않았음. */
                                                break;
                                        }

                                        s_nlattr = (struct nlattr *)(((uint8_t *)s_nlmsghdr) + s_offset);
                                        if (s_nlattr->nla_len < ((size_t)NLA_HDRLEN)) {
                                                /* attribute length 가 최소 크기를 만족하지 못함 */
                                                break;
                                        }

                                        if ((s_offset + ((size_t)NLA_ALIGN(s_nlattr->nla_len))) > ((size_t)s_nlmsghdr->nlmsg_len)) {
                                                /* attribute 공간이 nlmsg를 넘어섬 */
                                                break;
                                        }

                                        switch(s_nlattr->nla_type) { /* SeeAlso : CTRL_ATTR_XXXX in "include/uapi/linux/genetlink.h" */
                                                case CTRL_ATTR_UNSPEC: /* 0 */
                                                        break;
                                                case CTRL_ATTR_FAMILY_ID: /* 1 */
                                                        s_family_id = (int)(*((uint16_t *)(((uint8_t *)s_nlattr) + NLA_HDRLEN)));
#if 1L
                                                        if (s_family_id != (-1)) {
                                                                /* family id 를 인지했으므로 더이상의 attr은 볼 필요가 없음 */
                                                                s_is_break = 1;
                                                                break;
                                                        }
#endif
                                                        break;
                                                case CTRL_ATTR_FAMILY_NAME: /* 2 */
                                                        break;
                                                case CTRL_ATTR_VERSION: /* 3 */
                                                        break;
                                                case CTRL_ATTR_HDRSIZE: /* 4 */
                                                        break;
                                                case CTRL_ATTR_MAXATTR: /* 5 */
                                                        break;
                                                case CTRL_ATTR_OPS: /* 6 */
                                                        break;
                                                case CTRL_ATTR_MCAST_GROUPS: /* 7 */
                                                        break;
                                                default: /* 8 >= */
                                                        break;
                                        }

                                        s_offset += (size_t)NLA_ALIGN(s_nlattr->nla_len);
                                }
                                break;
                        default:
                                break;
                }
        }

        return(s_family_id);
}
}}}
 * Generic Netlink socket open 함수
 {{{#!enscript c
int hwport_open_generic_netlink(uint32_t s_port_id, uint32_t s_groups_mask)
{
        int s_socket;
        struct sockaddr_nl s_sockaddr_nl;

        s_socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
        if (s_socket == (-1)) {
                return(-1);
        }

        (void)memset((void *)(&s_sockaddr_nl), 0, sizeof(s_sockaddr_nl));
        s_sockaddr_nl.nl_family = AF_NETLINK;
#if 0L
        s_sockaddr_nl.nl_pad = 0;
#endif
        s_sockaddr_nl.nl_pid = s_port_id; /* port ID */
        s_sockaddr_nl.nl_groups = s_groups_mask; /* multicast groups mask */
        if (bind(s_socket, (struct sockaddr *)(&s_sockaddr_nl), (socklen_t)sizeof(s_sockaddr_nl)) == (-1)) {
                int s_check;
                int s_save_errno;

                s_save_errno = errno;
                do {
                        s_check = close(s_socket);
                }while((s_check == (-1)) && (errno == EINTR));
                errno = s_save_errno;
                return(-1);
        }

        return(s_socket);
}
}}}
 * Generic Netlink socket close 함수
 {{{#!enscript c
int hwport_close_generic_netlink(int s_socket)
{
        int s_check;

        if (s_socket == (-1)) {
                errno = EINVAL;
                return(-1);
        }

        do {
                s_check = close(s_socket);
        }while((s_check == (-1)) && (errno == EINTR));

        return(s_check);
}
}}}
=== 참고자료 ===
 * [^https://www.rfc-editor.org/rfc/rfc3549]
  * [^https://tools.ietf.org/html/rfc3549#section-2.3.2]
 * [^https://github.com/shemminger/iproute2] <= Netlink 구현은 이 소스가 이해하는데 많은 도움이 됩니다. (추천)
 * [^http://www.linuxfoundation.org/collaborate/workgroups/networking/generic_netlink_howto]
 * [^https://people.redhat.com/nhorman/papers/netlink.pdf]
 * [^http://inai.de/documents/Netlink_Protocol.pdf]
 * [^https://nscpolteksby.ac.id/ebook/files/Ebook/Computer%20Engineering/Linux%20Kernel%20Networking%20-%20Implementation%20(2014)/chapter%202%20Netlink%20Sockets.pdf]
 * [^https://people.netfilter.org/pablo/netlink/netlink-libmnl-manual.pdf]
 * [^http://haifux.org/lectures/219/netLec6.pdf]
 * [^https://medium.com/@mdlayher/linux-netlink-and-go-part-1-netlink-4781aaeeaca8]
 * [^https://stackoverrun.com/ko/q/7837552]
 * [^https://www.infradead.org/~tgr/libnl/doc/core.html]
 * [^https://www.ctolib.com/topics-134609.html]
 * [^http://linux-development-for-fresher.blogspot.com/2012/05/understanding-netlink-socket.html]
 * [^https://gist.github.com/arunk-s/c897bb9d75a6c98733d6]