1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * TCP Support with SACK for file transfer.
4 *
5 * Copyright 2017 Duncan Hare, All rights reserved.
6 */
7
8#define TCP_ACTIVITY 127		/* Number of packets received   */
9					/* before console progress mark */
10/**
11 * struct ip_tcp_hdr - IP and TCP header
12 * @ip_hl_v: header length and version
13 * @ip_tos: type of service
14 * @ip_len: total length
15 * @ip_id: identification
16 * @ip_off: fragment offset field
17 * @ip_ttl: time to live
18 * @ip_p: protocol
19 * @ip_sum: checksum
20 * @ip_src: Source IP address
21 * @ip_dst: Destination IP address
22 * @tcp_src: TCP source port
23 * @tcp_dst: TCP destination port
24 * @tcp_seq: TCP sequence number
25 * @tcp_ack: TCP Acknowledgment number
26 * @tcp_hlen: 4 bits TCP header Length/4, 4 bits reserved, 2 more bits reserved
27 * @tcp_flag: flags of TCP
28 * @tcp_win: TCP windows size
29 * @tcp_xsum: Checksum
30 * @tcp_ugr: Pointer to urgent data
31 */
32struct ip_tcp_hdr {
33	u8		ip_hl_v;
34	u8		ip_tos;
35	u16		ip_len;
36	u16		ip_id;
37	u16		ip_off;
38	u8		ip_ttl;
39	u8		ip_p;
40	u16		ip_sum;
41	struct in_addr	ip_src;
42	struct in_addr	ip_dst;
43	u16		tcp_src;
44	u16		tcp_dst;
45	u32		tcp_seq;
46	u32		tcp_ack;
47	u8		tcp_hlen;
48	u8		tcp_flags;
49	u16		tcp_win;
50	u16		tcp_xsum;
51	u16		tcp_ugr;
52} __packed;
53
54#define IP_TCP_HDR_SIZE		(sizeof(struct ip_tcp_hdr))
55#define TCP_HDR_SIZE		(IP_TCP_HDR_SIZE  - IP_HDR_SIZE)
56
57#define TCP_DATA	0x00	/* Data Packet - internal use only	*/
58#define TCP_FIN		0x01	/* Finish flag				*/
59#define TCP_SYN		0x02	/* Synch (start) flag			*/
60#define TCP_RST		0x04	/* reset flag				*/
61#define TCP_PUSH	0x08	/* Push - Notify app			*/
62#define TCP_ACK		0x10	/* Acknowledgment of data received	*/
63#define TCP_URG		0x20	/* Urgent				*/
64#define TCP_ECE		0x40	/* Congestion control			*/
65#define TCP_CWR		0x80	/* Congestion Control			*/
66
67/*
68 * TCP header options, Seq, MSS, and SACK
69 */
70
71#define TCP_SACK 32			/* Number of packets analyzed   */
72					/* on leading edge of stream    */
73
74#define TCP_O_END	0x00		/* End of option list		*/
75#define TCP_1_NOP	0x01		/* Single padding NOP		*/
76#define TCP_O_NOP	0x01010101	/* NOPs pad to 32 bit boundary	*/
77#define TCP_O_MSS	0x02		/* MSS Size option		*/
78#define TCP_O_SCL	0x03		/* Window Scale option		*/
79#define TCP_P_SACK	0x04		/* SACK permitted		*/
80#define TCP_V_SACK	0x05		/* SACK values			*/
81#define TCP_O_TS	0x08		/* Timestamp option		*/
82#define TCP_OPT_LEN_2	0x02
83#define TCP_OPT_LEN_3	0x03
84#define TCP_OPT_LEN_4	0x04
85#define TCP_OPT_LEN_6	0x06
86#define TCP_OPT_LEN_8	0x08
87#define TCP_OPT_LEN_A	0x0a		/* Timestamp Length		*/
88#define TCP_MSS		1460		/* Max segment size		*/
89#define TCP_SCALE	0x01		/* Scale			*/
90
91/**
92 * struct tcp_mss - TCP option structure for MSS (Max segment size)
93 * @kind: Field ID
94 * @len: Field length
95 * @mss: Segment size value
96 */
97struct tcp_mss {
98	u8	kind;
99	u8	len;
100	u16	mss;
101} __packed;
102
103/**
104 * struct tcp_scale - TCP option structure for Windows scale
105 * @kind: Field ID
106 * @len: Field length
107 * @scale: windows shift value used for networks with many hops.
108 *         Typically 4 or more hops
109 */
110struct tcp_scale {
111	u8	kind;
112	u8	len;
113	u8	scale;
114} __packed;
115
116/**
117 * struct tcp_sack_p - TCP option structure for SACK permitted
118 * @kind: Field ID
119 * @len: Field length
120 */
121struct tcp_sack_p {
122	u8	kind;
123	u8	len;
124} __packed;
125
126/**
127 * struct sack_edges - structure for SACK edges
128 * @l: Left edge of stream
129 * @r: right edge of stream
130 */
131struct sack_edges {
132	u32	l;
133	u32	r;
134} __packed;
135
136#define TCP_SACK_SIZE (sizeof(struct sack_edges))
137
138/*
139 * A TCP stream has holes when packets are missing or disordered.
140 * A hill is the inverse of a hole, and is data received.
141 * TCP received hills (a sequence of data), and inferrs Holes
142 * from the "hills" or packets received.
143 */
144
145#define TCP_SACK_HILLS	4
146
147/**
148 * struct tcp_sack_v - TCP option structure for SACK
149 * @kind: Field ID
150 * @len: Field length
151 * @hill: L & R window edges
152 */
153struct tcp_sack_v {
154	u8	kind;
155	u8	len;
156	struct	sack_edges hill[TCP_SACK_HILLS];
157} __packed;
158
159/**
160 * struct tcp_t_opt - TCP option structure for time stamps
161 * @kind: Field ID
162 * @len: Field length
163 * @t_snd: Sender timestamp
164 * @t_rcv: Receiver timestamp
165 */
166struct tcp_t_opt {
167	u8	kind;
168	u8	len;
169	u32	t_snd;
170	u32	t_rcv;
171} __packed;
172
173#define TCP_TSOPT_SIZE (sizeof(struct tcp_t_opt))
174
175/*
176 * ip tcp  structure with options
177 */
178
179/**
180 * struct ip_tcp_hdr_o - IP + TCP header + TCP options
181 * @hdr: IP + TCP header
182 * @mss: TCP MSS Option
183 * @scale: TCP Windows Scale Option
184 * @sack_p: TCP Sack-Permitted Option
185 * @t_opt: TCP Timestamp Option
186 * @end: end of options
187 */
188struct ip_tcp_hdr_o {
189	struct	ip_tcp_hdr hdr;
190	struct	tcp_mss	   mss;
191	struct	tcp_scale  scale;
192	struct	tcp_sack_p sack_p;
193	struct	tcp_t_opt  t_opt;
194	u8	end;
195} __packed;
196
197#define IP_TCP_O_SIZE (sizeof(struct ip_tcp_hdr_o))
198
199/**
200 * struct ip_tcp_hdr_s - IP + TCP header + TCP options
201 * @hdr: IP + TCP header
202 * @t_opt: TCP Timestamp Option
203 * @sack_v: TCP SACK Option
204 * @end: end of options
205 */
206struct ip_tcp_hdr_s {
207	struct	ip_tcp_hdr	hdr;
208	struct	tcp_t_opt	t_opt;
209	struct	tcp_sack_v	sack_v;
210	u8	end;
211} __packed;
212
213#define IP_TCP_SACK_SIZE (sizeof(struct ip_tcp_hdr_s))
214
215/*
216 * TCP pseudo header definitions
217 */
218#define PSEUDO_PAD_SIZE	8
219
220/**
221 * struct pseudo_hdr - Pseudo Header
222 * @padding: pseudo hdr size = ip_tcp hdr size
223 * @p_src: Source IP address
224 * @p_dst: Destination IP address
225 * @rsvd: reserved
226 * @p: protocol
227 * @len: length of header
228 */
229struct pseudo_hdr {
230	u8 padding[PSEUDO_PAD_SIZE];
231	struct in_addr p_src;
232	struct in_addr p_dst;
233	u8      rsvd;
234	u8      p;
235	u16     len;
236} __packed;
237
238#define PSEUDO_HDR_SIZE	(sizeof(struct pseudo_hdr)) - PSEUDO_PAD_SIZE
239
240/**
241 * union tcp_build_pkt - union for building TCP/IP packet.
242 * @ph: pseudo header
243 * @ip: IP and TCP header plus TCP options
244 * @sack: IP and TCP header plus SACK options
245 * @raw: buffer
246 *
247 * Build Pseudo header in packed buffer
248 * first, calculate TCP checksum, then build IP header in packed buffer.
249 *
250 */
251union tcp_build_pkt {
252	struct pseudo_hdr ph;
253	struct ip_tcp_hdr_o ip;
254	struct ip_tcp_hdr_s sack;
255	uchar  raw[1600];
256} __packed;
257
258/**
259 * enum tcp_state - TCP State machine states for connection
260 * @TCP_CLOSED: Need to send SYN to connect
261 * @TCP_SYN_SENT: Trying to connect, waiting for SYN ACK
262 * @TCP_SYN_RECEIVED: Initial SYN received, waiting for ACK
263 * @TCP_ESTABLISHED: both server & client have a connection
264 * @TCP_CLOSE_WAIT: Rec FIN, passed to app for FIN, ACK rsp
265 * @TCP_CLOSING: Rec FIN, sent FIN, ACK waiting for ACK
266 * @TCP_FIN_WAIT_1: Sent FIN waiting for response
267 * @TCP_FIN_WAIT_2: Rec ACK from FIN sent, waiting for FIN
268 */
269enum tcp_state {
270	TCP_CLOSED,
271	TCP_SYN_SENT,
272	TCP_SYN_RECEIVED,
273	TCP_ESTABLISHED,
274	TCP_CLOSE_WAIT,
275	TCP_CLOSING,
276	TCP_FIN_WAIT_1,
277	TCP_FIN_WAIT_2
278};
279
280enum tcp_state tcp_get_tcp_state(void);
281void tcp_set_tcp_state(enum tcp_state new_state);
282int tcp_set_tcp_header(uchar *pkt, int dport, int sport, int payload_len,
283		       u8 action, u32 tcp_seq_num, u32 tcp_ack_num);
284
285/**
286 * rxhand_tcp() - An incoming packet handler.
287 * @pkt: pointer to the application packet
288 * @dport: destination TCP port
289 * @sip: source IP address
290 * @sport: source TCP port
291 * @tcp_seq_num: TCP sequential number
292 * @tcp_ack_num: TCP acknowledgment number
293 * @action: TCP action (SYN, ACK, FIN, etc)
294 * @len: packet length
295 */
296typedef void rxhand_tcp(uchar *pkt, u16 dport,
297			struct in_addr sip, u16 sport,
298			u32 tcp_seq_num, u32 tcp_ack_num,
299			u8 action, unsigned int len);
300void tcp_set_tcp_handler(rxhand_tcp *f);
301
302void rxhand_tcp_f(union tcp_build_pkt *b, unsigned int len);
303
304u16 tcp_set_pseudo_header(uchar *pkt, struct in_addr src, struct in_addr dest,
305			  int tcp_len, int pkt_len);
306