2 * mss_clamp_node.c - Node implementing TCP MSS clamping
4 * Copyright (c) 2018 Cisco and/or its affiliates
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at:
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
17 #include <vlib/vlib.h>
18 #include <vnet/vnet.h>
19 #include <vnet/pg/pg.h>
20 #include <vppinfra/error.h>
21 #include <mss_clamp/mss_clamp.h>
22 #include <mss_clamp/mss_clamp.api_enum.h>
23 #include <vnet/fib/fib_types.h>
24 #include <vnet/feature/feature.h>
25 #include <vnet/ip/ip4.h>
26 #include <vnet/ip/ip6.h>
28 extern vlib_node_registration_t mssc_ip4_in_node, mssc_ip4_out_node;
29 extern vlib_node_registration_t mssc_ip6_in_node, mssc_ip6_out_node;
31 typedef struct mssc_trace_t_
37 /* packet trace format function */
39 format_mssc_trace (u8 *s, va_list *args)
41 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
42 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
43 mssc_trace_t *t = va_arg (*args, mssc_trace_t *);
45 s = format (s, "max mss: %d clamped: %d", t->max_mss, t->clamped);
56 * fixup the maximum segment size if it's a syn packet
57 * return 1 if the mss was changed otherwise 0
60 mssc_mss_fixup (vlib_buffer_t *b0, tcp_header_t *tcp0, u16 max_mss0)
64 if (PREDICT_FALSE (tcp_syn (tcp0)))
66 u8 opt_len, opts_len, kind;
70 opts_len = (tcp_doff (tcp0) << 2) - sizeof (tcp_header_t);
71 data = (const u8 *) (tcp0 + 1);
73 for (; opts_len > 0; opts_len -= opt_len, data += opt_len)
77 /* Get options length */
78 if (kind == TCP_OPTION_EOL)
80 else if (kind == TCP_OPTION_NOOP)
92 /* weird option length */
93 if (opt_len < 2 || opt_len > opts_len)
97 if (kind == TCP_OPTION_MSS)
99 mss0 = *(u16 *) (data + 2);
100 if (clib_net_to_host_u16 (mss0) > max_mss0)
102 new_mss0 = clib_host_to_net_u16 (max_mss0);
103 *((u16 *) (data + 2)) = new_mss0;
104 sum0 = tcp0->checksum;
105 sum0 = ip_csum_update (sum0, mss0, new_mss0, tcp_header_t,
107 tcp0->checksum = ip_csum_fold (sum0);
118 mssc_inline (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame,
119 vlib_dir_t dir, fib_protocol_t fproto)
121 mssc_main_t *cm = &mssc_main;
122 vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b;
123 u16 nexts[VLIB_FRAME_SIZE], *next;
125 u32 pkts_clamped = 0;
127 from = vlib_frame_vector_args (frame);
128 n_left = frame->n_vectors;
132 vlib_get_buffers (vm, from, bufs, n_left);
136 u32 sw_if_index0, sw_if_index1;
138 u32 clamped0, clamped1;
140 /* Prefetch next iteration. */
142 vlib_prefetch_buffer_header (b[2], LOAD);
143 vlib_prefetch_buffer_header (b[3], LOAD);
144 vlib_prefetch_buffer_data (b[2], LOAD);
145 vlib_prefetch_buffer_data (b[3], LOAD);
148 sw_if_index0 = vnet_buffer (b[0])->sw_if_index[dir];
149 sw_if_index1 = vnet_buffer (b[1])->sw_if_index[dir];
150 clamped0 = clamped1 = 0;
152 /* speculatively enqueue b0 to the current next frame */
153 vnet_feature_next_u16 (&next[0], b[0]);
154 vnet_feature_next_u16 (&next[1], b[1]);
156 h0 = (u8 *) vlib_buffer_get_current (b[0]);
157 h1 = (u8 *) vlib_buffer_get_current (b[1]);
160 h0 += vnet_buffer (b[0])->ip.save_rewrite_length;
161 h1 += vnet_buffer (b[1])->ip.save_rewrite_length;
164 if (FIB_PROTOCOL_IP4 == fproto)
166 ip4_header_t *ip0 = (ip4_header_t *) h0;
167 ip4_header_t *ip1 = (ip4_header_t *) h1;
169 if (IP_PROTOCOL_TCP == ip0->protocol)
171 clamped0 = mssc_mss_fixup (b[0], ip4_next_header (ip0),
172 cm->max_mss4[sw_if_index0]);
174 if (IP_PROTOCOL_TCP == ip1->protocol)
176 clamped1 = mssc_mss_fixup (b[1], ip4_next_header (ip1),
177 cm->max_mss4[sw_if_index1]);
180 else if (FIB_PROTOCOL_IP6 == fproto)
182 ip6_header_t *ip0 = (ip6_header_t *) h0;
183 ip6_header_t *ip1 = (ip6_header_t *) h1;
185 if (IP_PROTOCOL_TCP == ip0->protocol)
187 clamped0 = mssc_mss_fixup (b[0], ip6_next_header (ip0),
188 cm->max_mss6[sw_if_index0]);
190 if (IP_PROTOCOL_TCP == ip1->protocol)
192 clamped1 = mssc_mss_fixup (b[1], ip6_next_header (ip1),
193 cm->max_mss6[sw_if_index1]);
197 pkts_clamped += clamped0 + clamped1;
199 if (PREDICT_FALSE (node->flags & VLIB_NODE_FLAG_TRACE))
201 if (b[0]->flags & VLIB_BUFFER_IS_TRACED)
205 t = vlib_add_trace (vm, node, b[0], sizeof (*t));
206 t->max_mss = (FIB_PROTOCOL_IP4 == fproto) ?
207 cm->max_mss4[sw_if_index0] :
208 cm->max_mss6[sw_if_index0];
209 t->clamped = clamped0;
211 if (b[1]->flags & VLIB_BUFFER_IS_TRACED)
215 t = vlib_add_trace (vm, node, b[1], sizeof (*t));
216 t->max_mss = (FIB_PROTOCOL_IP4 == fproto) ?
217 cm->max_mss4[sw_if_index1] :
218 cm->max_mss6[sw_if_index1];
219 t->clamped = clamped1;
234 sw_if_index0 = vnet_buffer (b[0])->sw_if_index[dir];
237 /* speculatively enqueue b0 to the current next frame */
238 vnet_feature_next_u16 (&next[0], b[0]);
240 h0 = (u8 *) vlib_buffer_get_current (b[0]);
242 h0 += vnet_buffer (b[0])->ip.save_rewrite_length;
244 if (FIB_PROTOCOL_IP4 == fproto)
246 ip4_header_t *ip0 = (ip4_header_t *) h0;
248 if (IP_PROTOCOL_TCP == ip0->protocol)
250 clamped0 = mssc_mss_fixup (b[0], ip4_next_header (ip0),
251 cm->max_mss4[sw_if_index0]);
254 else if (FIB_PROTOCOL_IP6 == fproto)
256 ip6_header_t *ip0 = (ip6_header_t *) h0;
258 if (IP_PROTOCOL_TCP == ip0->protocol)
260 clamped0 = mssc_mss_fixup (b[0], ip6_next_header (ip0),
261 cm->max_mss6[sw_if_index0]);
265 pkts_clamped += clamped0;
267 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
268 (b[0]->flags & VLIB_BUFFER_IS_TRACED)))
272 t = vlib_add_trace (vm, node, b[0], sizeof (*t));
273 t->max_mss = (FIB_PROTOCOL_IP4 == fproto) ?
274 cm->max_mss4[sw_if_index0] :
275 cm->max_mss6[sw_if_index0];
276 t->clamped = clamped0;
284 vlib_buffer_enqueue_to_next (vm, node, from, nexts, frame->n_vectors);
285 vlib_node_increment_counter (vm, node->node_index, MSS_CLAMP_ERROR_CLAMPED,
288 return frame->n_vectors;
292 mssc_ip4_in (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
294 return (mssc_inline (vm, node, frame, VLIB_RX, FIB_PROTOCOL_IP4));
298 mssc_ip4_out (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
300 return (mssc_inline (vm, node, frame, VLIB_TX, FIB_PROTOCOL_IP4));
304 mssc_ip6_in (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
306 return (mssc_inline (vm, node, frame, VLIB_RX, FIB_PROTOCOL_IP6));
310 mssc_ip6_out (vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
312 return (mssc_inline (vm, node, frame, VLIB_TX, FIB_PROTOCOL_IP6));
315 VLIB_REGISTER_NODE (mssc_ip4_in_node) =
317 .function = mssc_ip4_in,
318 .name = "tcp-mss-clamping-ip4-in",
319 .vector_size = sizeof (u32),
320 .format_trace = format_mssc_trace,
321 .type = VLIB_NODE_TYPE_INTERNAL,
323 .n_errors = MSS_CLAMP_N_ERROR,
324 .error_counters = mss_clamp_error_counters,
326 .n_next_nodes = MSSC_N_NEXT,
328 [MSSC_NEXT_DROP] = "error-drop",
332 VLIB_REGISTER_NODE (mssc_ip4_out_node) =
334 .function = mssc_ip4_out,
335 .name = "tcp-mss-clamping-ip4-out",
336 .vector_size = sizeof (u32),
337 .format_trace = format_mssc_trace,
338 .type = VLIB_NODE_TYPE_INTERNAL,
340 .n_errors = MSS_CLAMP_N_ERROR,
341 .error_counters = mss_clamp_error_counters,
343 .n_next_nodes = MSSC_N_NEXT,
345 [MSSC_NEXT_DROP] = "error-drop",
349 VLIB_REGISTER_NODE (mssc_ip6_in_node) =
351 .function = mssc_ip6_in,
352 .name = "tcp-mss-clamping-ip6-in",
353 .vector_size = sizeof (u32),
354 .format_trace = format_mssc_trace,
355 .type = VLIB_NODE_TYPE_INTERNAL,
357 .n_errors = MSS_CLAMP_N_ERROR,
358 .error_counters = mss_clamp_error_counters,
360 .n_next_nodes = MSSC_N_NEXT,
362 [MSSC_NEXT_DROP] = "error-drop",
366 VLIB_REGISTER_NODE (mssc_ip6_out_node) =
368 .function = mssc_ip6_out,
369 .name = "tcp-mss-clamping-ip6-out",
370 .vector_size = sizeof (u32),
371 .format_trace = format_mssc_trace,
372 .type = VLIB_NODE_TYPE_INTERNAL,
374 .n_errors = MSS_CLAMP_N_ERROR,
375 .error_counters = mss_clamp_error_counters,
377 .n_next_nodes = MSSC_N_NEXT,
379 [MSSC_NEXT_DROP] = "error-drop",
383 VNET_FEATURE_INIT (mssc_ip4_in_feat, static) = {
384 .arc_name = "ip4-unicast",
385 .node_name = "tcp-mss-clamping-ip4-in",
386 .runs_after = VNET_FEATURES ("ip4-policer-classify"),
389 VNET_FEATURE_INIT (mssc_ip4_out_feat, static) = {
390 .arc_name = "ip4-output",
391 .node_name = "tcp-mss-clamping-ip4-out",
394 VNET_FEATURE_INIT (mssc_ip6_in_feat, static) = {
395 .arc_name = "ip6-unicast",
396 .node_name = "tcp-mss-clamping-ip6-in",
397 .runs_after = VNET_FEATURES ("ip6-policer-classify"),
400 VNET_FEATURE_INIT (mssc_ip6_out_feat, static) = {
401 .arc_name = "ip6-output",
402 .node_name = "tcp-mss-clamping-ip6-out",
406 * fd.io coding-style-patch-verification: ON
409 * eval: (c-set-style "gnu")