2 * Copyright (c) 2016-2019 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
16 #ifndef included_tcp_packet_h
17 #define included_tcp_packet_h
19 #include <vnet/vnet.h>
21 /* TCP flags bit 0 first. */
22 #define foreach_tcp_flag \
23 _ (FIN) /**< No more data from sender. */ \
24 _ (SYN) /**< Synchronize sequence numbers. */ \
25 _ (RST) /**< Reset the connection. */ \
26 _ (PSH) /**< Push function. */ \
27 _ (ACK) /**< Ack field significant. */ \
28 _ (URG) /**< Urgent pointer field significant. */ \
29 _ (ECE) /**< ECN-echo. Receiver got CE packet */ \
30 _ (CWR) /**< Sender reduced congestion window */
34 #define _(f) TCP_FLAG_BIT_##f,
42 #define _(f) TCP_FLAG_##f = 1 << TCP_FLAG_BIT_##f,
47 typedef struct _tcp_header
53 u16 src_port; /**< Source port. */
54 u16 dst_port; /**< Destination port. */
62 u32 seq_number; /**< Sequence number of the first data octet in this
63 * segment, except when SYN is present. If SYN
64 * is present the seq number is is the ISN and the
65 * first data octet is ISN+1 */
66 u32 ack_number; /**< Acknowledgement number if ACK is set. It contains
67 * the value of the next sequence number the sender
68 * of the segment is expecting to receive. */
69 u8 data_offset_and_reserved;
70 u8 flags; /**< Flags: see the macro above */
71 u16 window; /**< Number of bytes sender is willing to receive. */
73 u16 checksum; /**< Checksum of TCP pseudo header and data. */
74 u16 urgent_pointer; /**< Seq number of the byte after the urgent data. */
75 } __attribute__ ((packed)) tcp_header_t;
77 /* Flag tests that return 0 or !0 */
78 #define tcp_doff(_th) ((_th)->data_offset_and_reserved >> 4)
79 #define tcp_fin(_th) ((_th)->flags & TCP_FLAG_FIN)
80 #define tcp_syn(_th) ((_th)->flags & TCP_FLAG_SYN)
81 #define tcp_rst(_th) ((_th)->flags & TCP_FLAG_RST)
82 #define tcp_psh(_th) ((_th)->flags & TCP_FLAG_PSH)
83 #define tcp_ack(_th) ((_th)->flags & TCP_FLAG_ACK)
84 #define tcp_urg(_th) ((_th)->flags & TCP_FLAG_URG)
85 #define tcp_ece(_th) ((_th)->flags & TCP_FLAG_ECE)
86 #define tcp_cwr(_th) ((_th)->flags & TCP_FLAG_CWR)
88 /* Flag tests that return 0 or 1 */
89 #define tcp_is_syn(_th) !!((_th)->flags & TCP_FLAG_SYN)
90 #define tcp_is_fin(_th) !!((_th)->flags & TCP_FLAG_FIN)
93 tcp_header_bytes (tcp_header_t * t)
95 return tcp_doff (t) * sizeof (u32);
102 typedef enum tcp_option_type
104 TCP_OPTION_EOL = 0, /**< End of options. */
105 TCP_OPTION_NOOP = 1, /**< No operation. */
106 TCP_OPTION_MSS = 2, /**< Limit MSS. */
107 TCP_OPTION_WINDOW_SCALE = 3, /**< Window scale. */
108 TCP_OPTION_SACK_PERMITTED = 4, /**< Selective Ack permitted. */
109 TCP_OPTION_SACK_BLOCK = 5, /**< Selective Ack block. */
110 TCP_OPTION_TIMESTAMP = 8, /**< Timestamps. */
111 TCP_OPTION_UTO = 28, /**< User timeout. */
112 TCP_OPTION_AO = 29, /**< Authentication Option. */
115 #define foreach_tcp_options_flag \
116 _ (MSS) /**< MSS advertised in SYN */ \
117 _ (TSTAMP) /**< Timestamp capability advertised in SYN */ \
118 _ (WSCALE) /**< Wnd scale capability advertised in SYN */ \
119 _ (SACK_PERMITTED) /**< SACK capability advertised in SYN */ \
120 _ (SACK) /**< SACK present */
124 #define _(f) TCP_OPTS_FLAG_BIT_##f,
125 foreach_tcp_options_flag
127 TCP_OPTIONS_N_FLAG_BITS,
132 #define _(f) TCP_OPTS_FLAG_##f = 1 << TCP_OPTS_FLAG_BIT_##f,
133 foreach_tcp_options_flag
137 typedef struct _sack_block
139 u32 start; /**< Start sequence number */
140 u32 end; /**< End sequence number (first outside) */
145 u8 flags; /** Option flags, see above */
146 u8 wscale; /**< Window scale advertised */
147 u16 mss; /**< Maximum segment size advertised */
148 u32 tsval; /**< Timestamp value */
149 u32 tsecr; /**< Echoed/reflected time stamp */
150 sack_block_t *sacks; /**< SACK blocks */
151 u8 n_sack_blocks; /**< Number of SACKs blocks */
154 /* Flag tests that return 0 or !0 */
155 #define tcp_opts_mss(_to) ((_to)->flags & TCP_OPTS_FLAG_MSS)
156 #define tcp_opts_tstamp(_to) ((_to)->flags & TCP_OPTS_FLAG_TSTAMP)
157 #define tcp_opts_wscale(_to) ((_to)->flags & TCP_OPTS_FLAG_WSCALE)
158 #define tcp_opts_sack(_to) ((_to)->flags & TCP_OPTS_FLAG_SACK)
159 #define tcp_opts_sack_permitted(_to) ((_to)->flags & TCP_OPTS_FLAG_SACK_PERMITTED)
161 /* TCP option lengths */
162 #define TCP_OPTION_LEN_EOL 1
163 #define TCP_OPTION_LEN_NOOP 1
164 #define TCP_OPTION_LEN_MSS 4
165 #define TCP_OPTION_LEN_WINDOW_SCALE 3
166 #define TCP_OPTION_LEN_SACK_PERMITTED 2
167 #define TCP_OPTION_LEN_TIMESTAMP 10
168 #define TCP_OPTION_LEN_SACK_BLOCK 8
170 #define TCP_HDR_LEN_MAX 60
171 #define TCP_WND_MAX 65535U
172 #define TCP_MAX_WND_SCALE 14 /* See RFC 1323 */
173 #define TCP_OPTS_ALIGN 4
174 #define TCP_OPTS_MAX_SACK_BLOCKS 3
176 /* Modulo arithmetic for TCP sequence numbers */
177 #define seq_lt(_s1, _s2) ((i32)((_s1)-(_s2)) < 0)
178 #define seq_leq(_s1, _s2) ((i32)((_s1)-(_s2)) <= 0)
179 #define seq_gt(_s1, _s2) ((i32)((_s1)-(_s2)) > 0)
180 #define seq_geq(_s1, _s2) ((i32)((_s1)-(_s2)) >= 0)
181 #define seq_max(_s1, _s2) (seq_gt((_s1), (_s2)) ? (_s1) : (_s2))
183 /* Modulo arithmetic for timestamps */
184 #define timestamp_lt(_t1, _t2) ((i32)((_t1)-(_t2)) < 0)
185 #define timestamp_leq(_t1, _t2) ((i32)((_t1)-(_t2)) <= 0)
188 * Parse TCP header options.
190 * @param th TCP header
191 * @param to TCP options data structure to be populated
192 * @param is_syn set if packet is syn
193 * @return -1 if parsing failed
196 tcp_options_parse (tcp_header_t * th, tcp_options_t * to, u8 is_syn)
199 u8 opt_len, opts_len, kind;
203 opts_len = (tcp_doff (th) << 2) - sizeof (tcp_header_t);
204 data = (const u8 *) (th + 1);
206 /* Zero out all flags but those set in SYN */
207 to->flags &= (TCP_OPTS_FLAG_SACK_PERMITTED | TCP_OPTS_FLAG_WSCALE
208 | TCP_OPTS_FLAG_TSTAMP | TCP_OPTS_FLAG_MSS);
210 for (; opts_len > 0; opts_len -= opt_len, data += opt_len)
214 /* Get options length */
215 if (kind == TCP_OPTION_EOL)
217 else if (kind == TCP_OPTION_NOOP)
229 /* weird option length */
230 if (opt_len < 2 || opt_len > opts_len)
240 if ((opt_len == TCP_OPTION_LEN_MSS) && tcp_syn (th))
242 to->flags |= TCP_OPTS_FLAG_MSS;
243 to->mss = clib_net_to_host_u16 (*(u16 *) (data + 2));
246 case TCP_OPTION_WINDOW_SCALE:
249 if ((opt_len == TCP_OPTION_LEN_WINDOW_SCALE) && tcp_syn (th))
251 to->flags |= TCP_OPTS_FLAG_WSCALE;
252 to->wscale = data[2];
253 if (to->wscale > TCP_MAX_WND_SCALE)
254 to->wscale = TCP_MAX_WND_SCALE;
257 case TCP_OPTION_TIMESTAMP:
259 to->flags |= TCP_OPTS_FLAG_TSTAMP;
260 if ((to->flags & TCP_OPTS_FLAG_TSTAMP)
261 && opt_len == TCP_OPTION_LEN_TIMESTAMP)
263 to->tsval = clib_net_to_host_u32 (*(u32 *) (data + 2));
264 to->tsecr = clib_net_to_host_u32 (*(u32 *) (data + 6));
267 case TCP_OPTION_SACK_PERMITTED:
270 if (opt_len == TCP_OPTION_LEN_SACK_PERMITTED && tcp_syn (th))
271 to->flags |= TCP_OPTS_FLAG_SACK_PERMITTED;
273 case TCP_OPTION_SACK_BLOCK:
274 /* If SACK permitted was not advertised or a SYN, break */
275 if ((to->flags & TCP_OPTS_FLAG_SACK_PERMITTED) == 0 || tcp_syn (th))
278 /* If too short or not correctly formatted, break */
279 if (opt_len < 10 || ((opt_len - 2) % TCP_OPTION_LEN_SACK_BLOCK))
282 to->flags |= TCP_OPTS_FLAG_SACK;
283 to->n_sack_blocks = (opt_len - 2) / TCP_OPTION_LEN_SACK_BLOCK;
284 vec_reset_length (to->sacks);
285 for (j = 0; j < to->n_sack_blocks; j++)
287 b.start = clib_net_to_host_u32 (*(u32 *) (data + 2 + 8 * j));
288 b.end = clib_net_to_host_u32 (*(u32 *) (data + 6 + 8 * j));
289 vec_add1 (to->sacks, b);
293 /* Nothing to see here */
301 * Write TCP options to segment.
303 * @param data buffer where to write the options
304 * @param opts options to write
305 * @return length of options written
308 tcp_options_write (u8 * data, tcp_options_t * opts)
311 u32 buf, seq_len = 4;
313 if (tcp_opts_mss (opts))
315 *data++ = TCP_OPTION_MSS;
316 *data++ = TCP_OPTION_LEN_MSS;
317 buf = clib_host_to_net_u16 (opts->mss);
318 clib_memcpy_fast (data, &buf, sizeof (opts->mss));
319 data += sizeof (opts->mss);
320 opts_len += TCP_OPTION_LEN_MSS;
323 if (tcp_opts_wscale (opts))
325 *data++ = TCP_OPTION_WINDOW_SCALE;
326 *data++ = TCP_OPTION_LEN_WINDOW_SCALE;
327 *data++ = opts->wscale;
328 opts_len += TCP_OPTION_LEN_WINDOW_SCALE;
331 if (tcp_opts_sack_permitted (opts))
333 *data++ = TCP_OPTION_SACK_PERMITTED;
334 *data++ = TCP_OPTION_LEN_SACK_PERMITTED;
335 opts_len += TCP_OPTION_LEN_SACK_PERMITTED;
338 if (tcp_opts_tstamp (opts))
340 *data++ = TCP_OPTION_TIMESTAMP;
341 *data++ = TCP_OPTION_LEN_TIMESTAMP;
342 buf = clib_host_to_net_u32 (opts->tsval);
343 clib_memcpy_fast (data, &buf, sizeof (opts->tsval));
344 data += sizeof (opts->tsval);
345 buf = clib_host_to_net_u32 (opts->tsecr);
346 clib_memcpy_fast (data, &buf, sizeof (opts->tsecr));
347 data += sizeof (opts->tsecr);
348 opts_len += TCP_OPTION_LEN_TIMESTAMP;
351 if (tcp_opts_sack (opts))
355 if (opts->n_sack_blocks != 0)
357 *data++ = TCP_OPTION_SACK_BLOCK;
358 *data++ = 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
359 for (i = 0; i < opts->n_sack_blocks; i++)
361 buf = clib_host_to_net_u32 (opts->sacks[i].start);
362 clib_memcpy_fast (data, &buf, seq_len);
364 buf = clib_host_to_net_u32 (opts->sacks[i].end);
365 clib_memcpy_fast (data, &buf, seq_len);
368 opts_len += 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
372 /* Terminate TCP options */
375 *data++ = TCP_OPTION_EOL;
376 opts_len += TCP_OPTION_LEN_EOL;
379 /* Pad with zeroes to a u32 boundary */
382 *data++ = TCP_OPTION_NOOP;
383 opts_len += TCP_OPTION_LEN_NOOP;
388 #endif /* included_tcp_packet_h */
391 * fd.io coding-style-patch-verification: ON
394 * eval: (c-set-style "gnu")