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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-09 13:14:35 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-09 13:14:35 +0000
commit9b8a97db9ec4b795e29e72289005fbc58484ebeb (patch)
treee24ca2d68215e57b4759fe5c032629821eabb250 /include/uapi/linux/tcp.h
parentInitial commit. (diff)
downloadiproute2-9b8a97db9ec4b795e29e72289005fbc58484ebeb.tar.xz
iproute2-9b8a97db9ec4b795e29e72289005fbc58484ebeb.zip
Adding upstream version 6.8.0.upstream/6.8.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'include/uapi/linux/tcp.h')
-rw-r--r--include/uapi/linux/tcp.h486
1 files changed, 486 insertions, 0 deletions
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
new file mode 100644
index 0000000..a1b9fb3
--- /dev/null
+++ b/include/uapi/linux/tcp.h
@@ -0,0 +1,486 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * INET An implementation of the TCP/IP protocol suite for the LINUX
+ * operating system. INET is implemented using the BSD Socket
+ * interface as the means of communication with the user level.
+ *
+ * Definitions for the TCP protocol.
+ *
+ * Version: @(#)tcp.h 1.0.2 04/28/93
+ *
+ * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#ifndef _LINUX_TCP_H
+#define _LINUX_TCP_H
+
+#include <linux/types.h>
+#include <asm/byteorder.h>
+#include <linux/socket.h>
+
+struct tcphdr {
+ __be16 source;
+ __be16 dest;
+ __be32 seq;
+ __be32 ack_seq;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+ __u16 res1:4,
+ doff:4,
+ fin:1,
+ syn:1,
+ rst:1,
+ psh:1,
+ ack:1,
+ urg:1,
+ ece:1,
+ cwr:1;
+#elif defined(__BIG_ENDIAN_BITFIELD)
+ __u16 doff:4,
+ res1:4,
+ cwr:1,
+ ece:1,
+ urg:1,
+ ack:1,
+ psh:1,
+ rst:1,
+ syn:1,
+ fin:1;
+#else
+#error "Adjust your <asm/byteorder.h> defines"
+#endif
+ __be16 window;
+ __sum16 check;
+ __be16 urg_ptr;
+};
+
+/*
+ * The union cast uses a gcc extension to avoid aliasing problems
+ * (union is compatible to any of its members)
+ * This means this part of the code is -fstrict-aliasing safe now.
+ */
+union tcp_word_hdr {
+ struct tcphdr hdr;
+ __be32 words[5];
+};
+
+#define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3])
+
+enum {
+ TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000),
+ TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000),
+ TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000),
+ TCP_FLAG_ACK = __constant_cpu_to_be32(0x00100000),
+ TCP_FLAG_PSH = __constant_cpu_to_be32(0x00080000),
+ TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000),
+ TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000),
+ TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000),
+ TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0F000000),
+ TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000)
+};
+
+/*
+ * TCP general constants
+ */
+#define TCP_MSS_DEFAULT 536U /* IPv4 (RFC1122, RFC2581) */
+#define TCP_MSS_DESIRED 1220U /* IPv6 (tunneled), EDNS0 (RFC3226) */
+
+/* TCP socket options */
+#define TCP_NODELAY 1 /* Turn off Nagle's algorithm. */
+#define TCP_MAXSEG 2 /* Limit MSS */
+#define TCP_CORK 3 /* Never send partially complete segments */
+#define TCP_KEEPIDLE 4 /* Start keeplives after this period */
+#define TCP_KEEPINTVL 5 /* Interval between keepalives */
+#define TCP_KEEPCNT 6 /* Number of keepalives before death */
+#define TCP_SYNCNT 7 /* Number of SYN retransmits */
+#define TCP_LINGER2 8 /* Life time of orphaned FIN-WAIT-2 state */
+#define TCP_DEFER_ACCEPT 9 /* Wake up listener only when data arrive */
+#define TCP_WINDOW_CLAMP 10 /* Bound advertised window */
+#define TCP_INFO 11 /* Information about this connection. */
+#define TCP_QUICKACK 12 /* Block/reenable quick acks */
+#define TCP_CONGESTION 13 /* Congestion control algorithm */
+#define TCP_MD5SIG 14 /* TCP MD5 Signature (RFC2385) */
+#define TCP_THIN_LINEAR_TIMEOUTS 16 /* Use linear timeouts for thin streams*/
+#define TCP_THIN_DUPACK 17 /* Fast retrans. after 1 dupack */
+#define TCP_USER_TIMEOUT 18 /* How long for loss retry before timeout */
+#define TCP_REPAIR 19 /* TCP sock is under repair right now */
+#define TCP_REPAIR_QUEUE 20
+#define TCP_QUEUE_SEQ 21
+#define TCP_REPAIR_OPTIONS 22
+#define TCP_FASTOPEN 23 /* Enable FastOpen on listeners */
+#define TCP_TIMESTAMP 24
+#define TCP_NOTSENT_LOWAT 25 /* limit number of unsent bytes in write queue */
+#define TCP_CC_INFO 26 /* Get Congestion Control (optional) info */
+#define TCP_SAVE_SYN 27 /* Record SYN headers for new connections */
+#define TCP_SAVED_SYN 28 /* Get SYN headers recorded for connection */
+#define TCP_REPAIR_WINDOW 29 /* Get/set window parameters */
+#define TCP_FASTOPEN_CONNECT 30 /* Attempt FastOpen with connect */
+#define TCP_ULP 31 /* Attach a ULP to a TCP connection */
+#define TCP_MD5SIG_EXT 32 /* TCP MD5 Signature with extensions */
+#define TCP_FASTOPEN_KEY 33 /* Set the key for Fast Open (cookie) */
+#define TCP_FASTOPEN_NO_COOKIE 34 /* Enable TFO without a TFO cookie */
+#define TCP_ZEROCOPY_RECEIVE 35
+#define TCP_INQ 36 /* Notify bytes available to read as a cmsg on read */
+
+#define TCP_CM_INQ TCP_INQ
+
+#define TCP_TX_DELAY 37 /* delay outgoing packets by XX usec */
+
+#define TCP_AO_ADD_KEY 38 /* Add/Set MKT */
+#define TCP_AO_DEL_KEY 39 /* Delete MKT */
+#define TCP_AO_INFO 40 /* Set/list TCP-AO per-socket options */
+#define TCP_AO_GET_KEYS 41 /* List MKT(s) */
+#define TCP_AO_REPAIR 42 /* Get/Set SNEs and ISNs */
+
+#define TCP_REPAIR_ON 1
+#define TCP_REPAIR_OFF 0
+#define TCP_REPAIR_OFF_NO_WP -1 /* Turn off without window probes */
+
+struct tcp_repair_opt {
+ __u32 opt_code;
+ __u32 opt_val;
+};
+
+struct tcp_repair_window {
+ __u32 snd_wl1;
+ __u32 snd_wnd;
+ __u32 max_window;
+
+ __u32 rcv_wnd;
+ __u32 rcv_wup;
+};
+
+enum {
+ TCP_NO_QUEUE,
+ TCP_RECV_QUEUE,
+ TCP_SEND_QUEUE,
+ TCP_QUEUES_NR,
+};
+
+/* why fastopen failed from client perspective */
+enum tcp_fastopen_client_fail {
+ TFO_STATUS_UNSPEC, /* catch-all */
+ TFO_COOKIE_UNAVAILABLE, /* if not in TFO_CLIENT_NO_COOKIE mode */
+ TFO_DATA_NOT_ACKED, /* SYN-ACK did not ack SYN data */
+ TFO_SYN_RETRANSMITTED, /* SYN-ACK did not ack SYN data after timeout */
+};
+
+/* for TCP_INFO socket option */
+#define TCPI_OPT_TIMESTAMPS 1
+#define TCPI_OPT_SACK 2
+#define TCPI_OPT_WSCALE 4
+#define TCPI_OPT_ECN 8 /* ECN was negociated at TCP session init */
+#define TCPI_OPT_ECN_SEEN 16 /* we received at least one packet with ECT */
+#define TCPI_OPT_SYN_DATA 32 /* SYN-ACK acked data in SYN sent or rcvd */
+#define TCPI_OPT_USEC_TS 64 /* usec timestamps */
+
+/*
+ * Sender's congestion state indicating normal or abnormal situations
+ * in the last round of packets sent. The state is driven by the ACK
+ * information and timer events.
+ */
+enum tcp_ca_state {
+ /*
+ * Nothing bad has been observed recently.
+ * No apparent reordering, packet loss, or ECN marks.
+ */
+ TCP_CA_Open = 0,
+#define TCPF_CA_Open (1<<TCP_CA_Open)
+ /*
+ * The sender enters disordered state when it has received DUPACKs or
+ * SACKs in the last round of packets sent. This could be due to packet
+ * loss or reordering but needs further information to confirm packets
+ * have been lost.
+ */
+ TCP_CA_Disorder = 1,
+#define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
+ /*
+ * The sender enters Congestion Window Reduction (CWR) state when it
+ * has received ACKs with ECN-ECE marks, or has experienced congestion
+ * or packet discard on the sender host (e.g. qdisc).
+ */
+ TCP_CA_CWR = 2,
+#define TCPF_CA_CWR (1<<TCP_CA_CWR)
+ /*
+ * The sender is in fast recovery and retransmitting lost packets,
+ * typically triggered by ACK events.
+ */
+ TCP_CA_Recovery = 3,
+#define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
+ /*
+ * The sender is in loss recovery triggered by retransmission timeout.
+ */
+ TCP_CA_Loss = 4
+#define TCPF_CA_Loss (1<<TCP_CA_Loss)
+};
+
+struct tcp_info {
+ __u8 tcpi_state;
+ __u8 tcpi_ca_state;
+ __u8 tcpi_retransmits;
+ __u8 tcpi_probes;
+ __u8 tcpi_backoff;
+ __u8 tcpi_options;
+ __u8 tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
+ __u8 tcpi_delivery_rate_app_limited:1, tcpi_fastopen_client_fail:2;
+
+ __u32 tcpi_rto;
+ __u32 tcpi_ato;
+ __u32 tcpi_snd_mss;
+ __u32 tcpi_rcv_mss;
+
+ __u32 tcpi_unacked;
+ __u32 tcpi_sacked;
+ __u32 tcpi_lost;
+ __u32 tcpi_retrans;
+ __u32 tcpi_fackets;
+
+ /* Times. */
+ __u32 tcpi_last_data_sent;
+ __u32 tcpi_last_ack_sent; /* Not remembered, sorry. */
+ __u32 tcpi_last_data_recv;
+ __u32 tcpi_last_ack_recv;
+
+ /* Metrics. */
+ __u32 tcpi_pmtu;
+ __u32 tcpi_rcv_ssthresh;
+ __u32 tcpi_rtt;
+ __u32 tcpi_rttvar;
+ __u32 tcpi_snd_ssthresh;
+ __u32 tcpi_snd_cwnd;
+ __u32 tcpi_advmss;
+ __u32 tcpi_reordering;
+
+ __u32 tcpi_rcv_rtt;
+ __u32 tcpi_rcv_space;
+
+ __u32 tcpi_total_retrans;
+
+ __u64 tcpi_pacing_rate;
+ __u64 tcpi_max_pacing_rate;
+ __u64 tcpi_bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked */
+ __u64 tcpi_bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived */
+ __u32 tcpi_segs_out; /* RFC4898 tcpEStatsPerfSegsOut */
+ __u32 tcpi_segs_in; /* RFC4898 tcpEStatsPerfSegsIn */
+
+ __u32 tcpi_notsent_bytes;
+ __u32 tcpi_min_rtt;
+ __u32 tcpi_data_segs_in; /* RFC4898 tcpEStatsDataSegsIn */
+ __u32 tcpi_data_segs_out; /* RFC4898 tcpEStatsDataSegsOut */
+
+ __u64 tcpi_delivery_rate;
+
+ __u64 tcpi_busy_time; /* Time (usec) busy sending data */
+ __u64 tcpi_rwnd_limited; /* Time (usec) limited by receive window */
+ __u64 tcpi_sndbuf_limited; /* Time (usec) limited by send buffer */
+
+ __u32 tcpi_delivered;
+ __u32 tcpi_delivered_ce;
+
+ __u64 tcpi_bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut */
+ __u64 tcpi_bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans */
+ __u32 tcpi_dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups */
+ __u32 tcpi_reord_seen; /* reordering events seen */
+
+ __u32 tcpi_rcv_ooopack; /* Out-of-order packets received */
+
+ __u32 tcpi_snd_wnd; /* peer's advertised receive window after
+ * scaling (bytes)
+ */
+ __u32 tcpi_rcv_wnd; /* local advertised receive window after
+ * scaling (bytes)
+ */
+
+ __u32 tcpi_rehash; /* PLB or timeout triggered rehash attempts */
+
+ __u16 tcpi_total_rto; /* Total number of RTO timeouts, including
+ * SYN/SYN-ACK and recurring timeouts.
+ */
+ __u16 tcpi_total_rto_recoveries; /* Total number of RTO
+ * recoveries, including any
+ * unfinished recovery.
+ */
+ __u32 tcpi_total_rto_time; /* Total time spent in RTO recoveries
+ * in milliseconds, including any
+ * unfinished recovery.
+ */
+};
+
+/* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */
+enum {
+ TCP_NLA_PAD,
+ TCP_NLA_BUSY, /* Time (usec) busy sending data */
+ TCP_NLA_RWND_LIMITED, /* Time (usec) limited by receive window */
+ TCP_NLA_SNDBUF_LIMITED, /* Time (usec) limited by send buffer */
+ TCP_NLA_DATA_SEGS_OUT, /* Data pkts sent including retransmission */
+ TCP_NLA_TOTAL_RETRANS, /* Data pkts retransmitted */
+ TCP_NLA_PACING_RATE, /* Pacing rate in bytes per second */
+ TCP_NLA_DELIVERY_RATE, /* Delivery rate in bytes per second */
+ TCP_NLA_SND_CWND, /* Sending congestion window */
+ TCP_NLA_REORDERING, /* Reordering metric */
+ TCP_NLA_MIN_RTT, /* minimum RTT */
+ TCP_NLA_RECUR_RETRANS, /* Recurring retransmits for the current pkt */
+ TCP_NLA_DELIVERY_RATE_APP_LMT, /* delivery rate application limited ? */
+ TCP_NLA_SNDQ_SIZE, /* Data (bytes) pending in send queue */
+ TCP_NLA_CA_STATE, /* ca_state of socket */
+ TCP_NLA_SND_SSTHRESH, /* Slow start size threshold */
+ TCP_NLA_DELIVERED, /* Data pkts delivered incl. out-of-order */
+ TCP_NLA_DELIVERED_CE, /* Like above but only ones w/ CE marks */
+ TCP_NLA_BYTES_SENT, /* Data bytes sent including retransmission */
+ TCP_NLA_BYTES_RETRANS, /* Data bytes retransmitted */
+ TCP_NLA_DSACK_DUPS, /* DSACK blocks received */
+ TCP_NLA_REORD_SEEN, /* reordering events seen */
+ TCP_NLA_SRTT, /* smoothed RTT in usecs */
+ TCP_NLA_TIMEOUT_REHASH, /* Timeout-triggered rehash attempts */
+ TCP_NLA_BYTES_NOTSENT, /* Bytes in write queue not yet sent */
+ TCP_NLA_EDT, /* Earliest departure time (CLOCK_MONOTONIC) */
+ TCP_NLA_TTL, /* TTL or hop limit of a packet received */
+ TCP_NLA_REHASH, /* PLB and timeout triggered rehash attempts */
+};
+
+/* for TCP_MD5SIG socket option */
+#define TCP_MD5SIG_MAXKEYLEN 80
+
+/* tcp_md5sig extension flags for TCP_MD5SIG_EXT */
+#define TCP_MD5SIG_FLAG_PREFIX 0x1 /* address prefix length */
+#define TCP_MD5SIG_FLAG_IFINDEX 0x2 /* ifindex set */
+
+struct tcp_md5sig {
+ struct __kernel_sockaddr_storage tcpm_addr; /* address associated */
+ __u8 tcpm_flags; /* extension flags */
+ __u8 tcpm_prefixlen; /* address prefix */
+ __u16 tcpm_keylen; /* key length */
+ int tcpm_ifindex; /* device index for scope */
+ __u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN]; /* key (binary) */
+};
+
+/* INET_DIAG_MD5SIG */
+struct tcp_diag_md5sig {
+ __u8 tcpm_family;
+ __u8 tcpm_prefixlen;
+ __u16 tcpm_keylen;
+ __be32 tcpm_addr[4];
+ __u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN];
+};
+
+#define TCP_AO_MAXKEYLEN 80
+
+#define TCP_AO_KEYF_IFINDEX (1 << 0) /* L3 ifindex for VRF */
+#define TCP_AO_KEYF_EXCLUDE_OPT (1 << 1) /* "Indicates whether TCP
+ * options other than TCP-AO
+ * are included in the MAC
+ * calculation"
+ */
+
+struct tcp_ao_add { /* setsockopt(TCP_AO_ADD_KEY) */
+ struct __kernel_sockaddr_storage addr; /* peer's address for the key */
+ char alg_name[64]; /* crypto hash algorithm to use */
+ __s32 ifindex; /* L3 dev index for VRF */
+ __u32 set_current :1, /* set key as Current_key at once */
+ set_rnext :1, /* request it from peer with RNext_key */
+ reserved :30; /* must be 0 */
+ __u16 reserved2; /* padding, must be 0 */
+ __u8 prefix; /* peer's address prefix */
+ __u8 sndid; /* SendID for outgoing segments */
+ __u8 rcvid; /* RecvID to match for incoming seg */
+ __u8 maclen; /* length of authentication code (hash) */
+ __u8 keyflags; /* see TCP_AO_KEYF_ */
+ __u8 keylen; /* length of ::key */
+ __u8 key[TCP_AO_MAXKEYLEN];
+} __attribute__((aligned(8)));
+
+struct tcp_ao_del { /* setsockopt(TCP_AO_DEL_KEY) */
+ struct __kernel_sockaddr_storage addr; /* peer's address for the key */
+ __s32 ifindex; /* L3 dev index for VRF */
+ __u32 set_current :1, /* corresponding ::current_key */
+ set_rnext :1, /* corresponding ::rnext */
+ del_async :1, /* only valid for listen sockets */
+ reserved :29; /* must be 0 */
+ __u16 reserved2; /* padding, must be 0 */
+ __u8 prefix; /* peer's address prefix */
+ __u8 sndid; /* SendID for outgoing segments */
+ __u8 rcvid; /* RecvID to match for incoming seg */
+ __u8 current_key; /* KeyID to set as Current_key */
+ __u8 rnext; /* KeyID to set as Rnext_key */
+ __u8 keyflags; /* see TCP_AO_KEYF_ */
+} __attribute__((aligned(8)));
+
+struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO), getsockopt(TCP_AO_INFO) */
+ /* Here 'in' is for setsockopt(), 'out' is for getsockopt() */
+ __u32 set_current :1, /* in/out: corresponding ::current_key */
+ set_rnext :1, /* in/out: corresponding ::rnext */
+ ao_required :1, /* in/out: don't accept non-AO connects */
+ set_counters :1, /* in: set/clear ::pkt_* counters */
+ accept_icmps :1, /* in/out: accept incoming ICMPs */
+ reserved :27; /* must be 0 */
+ __u16 reserved2; /* padding, must be 0 */
+ __u8 current_key; /* in/out: KeyID of Current_key */
+ __u8 rnext; /* in/out: keyid of RNext_key */
+ __u64 pkt_good; /* in/out: verified segments */
+ __u64 pkt_bad; /* in/out: failed verification */
+ __u64 pkt_key_not_found; /* in/out: could not find a key to verify */
+ __u64 pkt_ao_required; /* in/out: segments missing TCP-AO sign */
+ __u64 pkt_dropped_icmp; /* in/out: ICMPs that were ignored */
+} __attribute__((aligned(8)));
+
+struct tcp_ao_getsockopt { /* getsockopt(TCP_AO_GET_KEYS) */
+ struct __kernel_sockaddr_storage addr; /* in/out: dump keys for peer
+ * with this address/prefix
+ */
+ char alg_name[64]; /* out: crypto hash algorithm */
+ __u8 key[TCP_AO_MAXKEYLEN];
+ __u32 nkeys; /* in: size of the userspace buffer
+ * @optval, measured in @optlen - the
+ * sizeof(struct tcp_ao_getsockopt)
+ * out: number of keys that matched
+ */
+ __u16 is_current :1, /* in: match and dump Current_key,
+ * out: the dumped key is Current_key
+ */
+
+ is_rnext :1, /* in: match and dump RNext_key,
+ * out: the dumped key is RNext_key
+ */
+ get_all :1, /* in: dump all keys */
+ reserved :13; /* padding, must be 0 */
+ __u8 sndid; /* in/out: dump keys with SendID */
+ __u8 rcvid; /* in/out: dump keys with RecvID */
+ __u8 prefix; /* in/out: dump keys with address/prefix */
+ __u8 maclen; /* out: key's length of authentication
+ * code (hash)
+ */
+ __u8 keyflags; /* in/out: see TCP_AO_KEYF_ */
+ __u8 keylen; /* out: length of ::key */
+ __s32 ifindex; /* in/out: L3 dev index for VRF */
+ __u64 pkt_good; /* out: verified segments */
+ __u64 pkt_bad; /* out: segments that failed verification */
+} __attribute__((aligned(8)));
+
+struct tcp_ao_repair { /* {s,g}etsockopt(TCP_AO_REPAIR) */
+ __be32 snt_isn;
+ __be32 rcv_isn;
+ __u32 snd_sne;
+ __u32 rcv_sne;
+} __attribute__((aligned(8)));
+
+/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
+
+#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1
+struct tcp_zerocopy_receive {
+ __u64 address; /* in: address of mapping */
+ __u32 length; /* in/out: number of bytes to map/mapped */
+ __u32 recv_skip_hint; /* out: amount of bytes to skip */
+ __u32 inq; /* out: amount of bytes in read queue */
+ __s32 err; /* out: socket error */
+ __u64 copybuf_address; /* in: copybuf address (small reads) */
+ __s32 copybuf_len; /* in/out: copybuf bytes avail/used or error */
+ __u32 flags; /* in: flags */
+ __u64 msg_control; /* ancillary data */
+ __u64 msg_controllen;
+ __u32 msg_flags;
+ __u32 reserved; /* set to 0 for now */
+};
+#endif /* _LINUX_TCP_H */