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1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Definitions for the TCP protocol.
7  *
8  * Version:	@(#)tcp.h	1.0.2	04/28/93
9  *
10  * Author:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11  *
12  *		This program is free software; you can redistribute it and/or
13  *		modify it under the terms of the GNU General Public License
14  *		as published by the Free Software Foundation; either version
15  *		2 of the License, or (at your option) any later version.
16  */
17 #ifndef _LINUX_TCP_H
18 #define _LINUX_TCP_H
19 
20 #include <linux/types.h>
21 #include <asm/byteorder.h>
22 #include <linux/socket.h>
23 
24 struct tcphdr {
25 	__be16	source;
26 	__be16	dest;
27 	__be32	seq;
28 	__be32	ack_seq;
29 #if defined(__LITTLE_ENDIAN_BITFIELD)
30 	__u16	res1:4,
31 		doff:4,
32 		fin:1,
33 		syn:1,
34 		rst:1,
35 		psh:1,
36 		ack:1,
37 		urg:1,
38 		ece:1,
39 		cwr:1;
40 #elif defined(__BIG_ENDIAN_BITFIELD)
41 	__u16	doff:4,
42 		res1:4,
43 		cwr:1,
44 		ece:1,
45 		urg:1,
46 		ack:1,
47 		psh:1,
48 		rst:1,
49 		syn:1,
50 		fin:1;
51 #else
52 #error	"Adjust your <asm/byteorder.h> defines"
53 #endif
54 	__be16	window;
55 	__sum16	check;
56 	__be16	urg_ptr;
57 };
58 
59 /*
60  *	The union cast uses a gcc extension to avoid aliasing problems
61  *  (union is compatible to any of its members)
62  *  This means this part of the code is -fstrict-aliasing safe now.
63  */
64 union tcp_word_hdr {
65 	struct tcphdr hdr;
66 	__be32 		  words[5];
67 };
68 
69 #define tcp_flag_word(tp) ( ((union tcp_word_hdr *)(tp))->words [3])
70 
71 enum {
72 	TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000),
73 	TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000),
74 	TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000),
75 	TCP_FLAG_ACK = __constant_cpu_to_be32(0x00100000),
76 	TCP_FLAG_PSH = __constant_cpu_to_be32(0x00080000),
77 	TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000),
78 	TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000),
79 	TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000),
80 	TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0F000000),
81 	TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000)
82 };
83 
84 /*
85  * TCP general constants
86  */
87 #define TCP_MSS_DEFAULT		 536U	/* IPv4 (RFC1122, RFC2581) */
88 #define TCP_MSS_DESIRED		1220U	/* IPv6 (tunneled), EDNS0 (RFC3226) */
89 
90 /* TCP socket options */
91 #define TCP_NODELAY		1	/* Turn off Nagle's algorithm. */
92 #define TCP_MAXSEG		2	/* Limit MSS */
93 #define TCP_CORK		3	/* Never send partially complete segments */
94 #define TCP_KEEPIDLE		4	/* Start keeplives after this period */
95 #define TCP_KEEPINTVL		5	/* Interval between keepalives */
96 #define TCP_KEEPCNT		6	/* Number of keepalives before death */
97 #define TCP_SYNCNT		7	/* Number of SYN retransmits */
98 #define TCP_LINGER2		8	/* Life time of orphaned FIN-WAIT-2 state */
99 #define TCP_DEFER_ACCEPT	9	/* Wake up listener only when data arrive */
100 #define TCP_WINDOW_CLAMP	10	/* Bound advertised window */
101 #define TCP_INFO		11	/* Information about this connection. */
102 #define TCP_QUICKACK		12	/* Block/reenable quick acks */
103 #define TCP_CONGESTION		13	/* Congestion control algorithm */
104 #define TCP_MD5SIG		14	/* TCP MD5 Signature (RFC2385) */
105 #define TCP_THIN_LINEAR_TIMEOUTS 16      /* Use linear timeouts for thin streams*/
106 #define TCP_THIN_DUPACK         17      /* Fast retrans. after 1 dupack */
107 #define TCP_USER_TIMEOUT	18	/* How long for loss retry before timeout */
108 #define TCP_REPAIR		19	/* TCP sock is under repair right now */
109 #define TCP_REPAIR_QUEUE	20
110 #define TCP_QUEUE_SEQ		21
111 #define TCP_REPAIR_OPTIONS	22
112 #define TCP_FASTOPEN		23	/* Enable FastOpen on listeners */
113 #define TCP_TIMESTAMP		24
114 #define TCP_NOTSENT_LOWAT	25	/* limit number of unsent bytes in write queue */
115 #define TCP_CC_INFO		26	/* Get Congestion Control (optional) info */
116 #define TCP_SAVE_SYN		27	/* Record SYN headers for new connections */
117 #define TCP_SAVED_SYN		28	/* Get SYN headers recorded for connection */
118 
119 struct tcp_repair_opt {
120 	__u32	opt_code;
121 	__u32	opt_val;
122 };
123 
124 enum {
125 	TCP_NO_QUEUE,
126 	TCP_RECV_QUEUE,
127 	TCP_SEND_QUEUE,
128 	TCP_QUEUES_NR,
129 };
130 
131 /* for TCP_INFO socket option */
132 #define TCPI_OPT_TIMESTAMPS	1
133 #define TCPI_OPT_SACK		2
134 #define TCPI_OPT_WSCALE		4
135 #define TCPI_OPT_ECN		8 /* ECN was negociated at TCP session init */
136 #define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */
137 #define TCPI_OPT_SYN_DATA	32 /* SYN-ACK acked data in SYN sent or rcvd */
138 
139 enum tcp_ca_state {
140 	TCP_CA_Open = 0,
141 #define TCPF_CA_Open	(1<<TCP_CA_Open)
142 	TCP_CA_Disorder = 1,
143 #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
144 	TCP_CA_CWR = 2,
145 #define TCPF_CA_CWR	(1<<TCP_CA_CWR)
146 	TCP_CA_Recovery = 3,
147 #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
148 	TCP_CA_Loss = 4
149 #define TCPF_CA_Loss	(1<<TCP_CA_Loss)
150 };
151 
152 struct tcp_info {
153 	__u8	tcpi_state;
154 	__u8	tcpi_ca_state;
155 	__u8	tcpi_retransmits;
156 	__u8	tcpi_probes;
157 	__u8	tcpi_backoff;
158 	__u8	tcpi_options;
159 	__u8	tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
160 
161 	__u32	tcpi_rto;
162 	__u32	tcpi_ato;
163 	__u32	tcpi_snd_mss;
164 	__u32	tcpi_rcv_mss;
165 
166 	__u32	tcpi_unacked;
167 	__u32	tcpi_sacked;
168 	__u32	tcpi_lost;
169 	__u32	tcpi_retrans;
170 	__u32	tcpi_fackets;
171 
172 	/* Times. */
173 	__u32	tcpi_last_data_sent;
174 	__u32	tcpi_last_ack_sent;     /* Not remembered, sorry. */
175 	__u32	tcpi_last_data_recv;
176 	__u32	tcpi_last_ack_recv;
177 
178 	/* Metrics. */
179 	__u32	tcpi_pmtu;
180 	__u32	tcpi_rcv_ssthresh;
181 	__u32	tcpi_rtt;
182 	__u32	tcpi_rttvar;
183 	__u32	tcpi_snd_ssthresh;
184 	__u32	tcpi_snd_cwnd;
185 	__u32	tcpi_advmss;
186 	__u32	tcpi_reordering;
187 
188 	__u32	tcpi_rcv_rtt;
189 	__u32	tcpi_rcv_space;
190 
191 	__u32	tcpi_total_retrans;
192 
193 	__u64	tcpi_pacing_rate;
194 	__u64	tcpi_max_pacing_rate;
195 	__u64	tcpi_bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked */
196 	__u64	tcpi_bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived */
197 	__u32	tcpi_segs_out;	     /* RFC4898 tcpEStatsPerfSegsOut */
198 	__u32	tcpi_segs_in;	     /* RFC4898 tcpEStatsPerfSegsIn */
199 };
200 
201 /* for TCP_MD5SIG socket option */
202 #define TCP_MD5SIG_MAXKEYLEN	80
203 
204 struct tcp_md5sig {
205 	struct __kernel_sockaddr_storage tcpm_addr;	/* address associated */
206 	__u16	__tcpm_pad1;				/* zero */
207 	__u16	tcpm_keylen;				/* key length */
208 	__u32	__tcpm_pad2;				/* zero */
209 	__u8	tcpm_key[TCP_MD5SIG_MAXKEYLEN];		/* key (binary) */
210 };
211 
212 #endif /* _LINUX_TCP_H */
213