2 * Copyright (c) 2017 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 * ioam_cache_tunnel_select_node.c
17 * This file implements anycast server selection using ioam data
18 * attached to anycast service selection.
19 * Anycast service is reachable via multiple servers reachable
21 * Works with TCP Anycast application.
22 * Cache entry is created when TCP SYN is received for anycast destination.
23 * Response TCP SYN ACKs for anycast service is compared and selected
24 * response is forwarded.
25 * The functionality is introduced via graph nodes that are hooked into
26 * vnet graph via classifier configs like below:
28 * Enable anycast service selection:
29 * set ioam ip6 sr-tunnel-select oneway
31 * Enable following classifier on the anycast service client facing interface
32 * e.g. anycast service is db06::06 then:
33 * classify session acl-hit-next ip6-node ip6-add-syn-hop-by-hop table-index 0 match l3
34 * ip6 dst db06::06 ioam-encap anycast
36 * Enable following classifier on the interfaces facing the server of anycast service:
37 * classify session acl-hit-next ip6-node ip6-lookup table-index 0 match l3
38 * ip6 src db06::06 ioam-decap anycast
41 #include <vlib/vlib.h>
42 #include <vnet/vnet.h>
43 #include <vnet/pg/pg.h>
44 #include <vppinfra/error.h>
45 #include <vnet/ip/ip.h>
46 #include <vnet/sr/sr.h>
47 #include <ioam/ip6/ioam_cache.h>
48 #include <vnet/ip/ip6_hop_by_hop.h>
49 #include <vnet/ip/ip6_hop_by_hop_packet.h>
57 /* packet trace format function */
59 format_cache_ts_trace (u8 * s, va_list * args)
61 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
62 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
63 cache_ts_trace_t *t = va_arg (*args, cache_ts_trace_t *);
65 s = format (s, "CACHE: flow_label %d, next index %d",
66 t->flow_label, t->next_index);
70 vlib_node_registration_t ioam_cache_ts_node;
72 #define foreach_cache_ts_error \
73 _(RECORDED, "ip6 iOAM headers cached")
77 #define _(sym,str) CACHE_TS_ERROR_##sym,
78 foreach_cache_ts_error
83 static char *cache_ts_error_strings[] = {
84 #define _(sym,string) string,
85 foreach_cache_ts_error
91 IOAM_CACHE_TS_NEXT_POP_HBYH,
92 IOAM_CACHE_TS_ERROR_NEXT_DROP,
97 ip6_ioam_cache_ts_node_fn (vlib_main_t * vm,
98 vlib_node_runtime_t * node, vlib_frame_t * frame)
100 ioam_cache_main_t *cm = &ioam_cache_main;
101 u32 n_left_from, *from, *to_next;
102 cache_ts_next_t next_index;
105 from = vlib_frame_vector_args (frame);
106 n_left_from = frame->n_vectors;
107 next_index = node->cached_next_index;
109 while (n_left_from > 0)
113 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
115 while (n_left_from > 0 && n_left_to_next > 0)
119 u32 next0 = IOAM_CACHE_TS_NEXT_POP_HBYH;
121 ip6_hop_by_hop_header_t *hbh0, *hbh_cmp;
124 u32 cache_ts_index = 0;
125 u8 cache_thread_id = 0;
133 p0 = vlib_get_buffer (vm, bi0);
134 ip0 = vlib_buffer_get_current (p0);
135 if (IP_PROTOCOL_TCP ==
136 ip6_locate_header (p0, ip0, IP_PROTOCOL_TCP, &tcp_offset0))
138 tcp0 = (tcp_header_t *) ((u8 *) ip0 + tcp_offset0);
139 if ((tcp0->flags & TCP_FLAG_SYN) == TCP_FLAG_SYN &&
140 (tcp0->flags & TCP_FLAG_ACK) == TCP_FLAG_ACK)
142 /* Look up and compare */
143 hbh0 = (ip6_hop_by_hop_header_t *) (ip0 + 1);
145 if (0 == ioam_cache_ts_lookup (ip0,
152 (tcp0->ack_number), &hbh_cmp,
154 &cache_thread_id, 1))
160 ip6_ioam_analyse_compare_path_delay (hbh0, hbh_cmp,
161 cm->criteria_oneway);
164 /* current syn/ack is worse than the earlier: Drop */
165 next0 = IOAM_CACHE_TS_ERROR_NEXT_DROP;
166 /* Check if all responses are received or time has exceeded
167 send cached response if yes */
168 ioam_cache_ts_check_and_send (cache_thread_id,
173 /* Update cache with this buffer */
174 /* If successfully updated then skip sending it */
177 ioam_cache_ts_update (cache_thread_id,
184 next0 = IOAM_CACHE_TS_ERROR_NEXT_DROP;
189 next0 = IOAM_CACHE_TS_ERROR_NEXT_DROP;
192 else if ((tcp0->flags & TCP_FLAG_RST) == TCP_FLAG_RST)
194 /* Look up and compare */
195 hbh0 = (ip6_hop_by_hop_header_t *) (ip0 + 1);
196 if (0 == ioam_cache_ts_lookup (ip0, hbh0->protocol, clib_net_to_host_u16 (tcp0->src_port), clib_net_to_host_u16 (tcp0->dst_port), clib_net_to_host_u32 (tcp0->ack_number), &hbh_cmp, &cache_ts_index, &cache_thread_id, 1)) //response seen
198 next0 = IOAM_CACHE_TS_ERROR_NEXT_DROP;
200 ioam_cache_ts_check_and_send (cache_thread_id,
206 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
208 if (p0->flags & VLIB_BUFFER_IS_TRACED)
210 cache_ts_trace_t *t =
211 vlib_add_trace (vm, node, p0, sizeof (*t));
214 (ip0->ip_version_traffic_class_and_flow_label);
215 t->next_index = next0;
218 /* verify speculative enqueue, maybe switch current next frame */
224 vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
225 to_next, n_left_to_next,
230 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
232 vlib_node_increment_counter (vm, ioam_cache_ts_node.index,
233 CACHE_TS_ERROR_RECORDED, recorded);
234 return frame->n_vectors;
238 * Node for IP6 iOAM header cache
241 VLIB_REGISTER_NODE (ioam_cache_ts_node) =
243 .function = ip6_ioam_cache_ts_node_fn,
244 .name = "ip6-ioam-tunnel-select",
245 .vector_size = sizeof (u32),
246 .format_trace = format_cache_ts_trace,
247 .type = VLIB_NODE_TYPE_INTERNAL,
248 .n_errors = ARRAY_LEN (cache_ts_error_strings),
249 .error_strings = cache_ts_error_strings,
250 .n_next_nodes = IOAM_CACHE_TS_N_NEXT,
251 /* edit / add dispositions here */
254 [IOAM_CACHE_TS_NEXT_POP_HBYH] = "ip6-pop-hop-by-hop",
255 [IOAM_CACHE_TS_ERROR_NEXT_DROP] = "error-drop",
263 } ip6_reset_ts_hbh_trace_t;
265 /* packet trace format function */
267 format_ip6_reset_ts_hbh_trace (u8 * s, va_list * args)
269 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
270 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
271 ip6_reset_ts_hbh_trace_t *t = va_arg (*args,
272 ip6_reset_ts_hbh_trace_t *);
275 format (s, "IP6_IOAM_RESET_TUNNEL_SELECT_HBH: next index %d",
280 vlib_node_registration_t ip6_reset_ts_hbh_node;
282 #define foreach_ip6_reset_ts_hbh_error \
283 _(PROCESSED, "iOAM Syn/Ack Pkts processed") \
284 _(SAVED, "iOAM Syn Pkts state saved") \
285 _(REMOVED, "iOAM Syn/Ack Pkts state removed")
289 #define _(sym,str) IP6_RESET_TS_HBH_ERROR_##sym,
290 foreach_ip6_reset_ts_hbh_error
292 IP6_RESET_TS_HBH_N_ERROR,
293 } ip6_reset_ts_hbh_error_t;
295 static char *ip6_reset_ts_hbh_error_strings[] = {
296 #define _(sym,string) string,
297 foreach_ip6_reset_ts_hbh_error
301 #define foreach_ip6_ioam_cache_ts_input_next \
302 _(IP6_LOOKUP, "ip6-lookup") \
303 _(DROP, "error-drop")
307 #define _(s,n) IP6_IOAM_CACHE_TS_INPUT_NEXT_##s,
308 foreach_ip6_ioam_cache_ts_input_next
310 IP6_IOAM_CACHE_TS_INPUT_N_NEXT,
311 } ip6_ioam_cache_ts_input_next_t;
315 ip6_reset_ts_hbh_node_fn (vlib_main_t * vm,
316 vlib_node_runtime_t * node, vlib_frame_t * frame)
318 ioam_cache_main_t *cm = &ioam_cache_main;
319 u32 n_left_from, *from, *to_next;
320 ip_lookup_next_t next_index;
321 u32 processed = 0, cache_ts_added = 0;
323 u8 *rewrite = cm->rewrite;
324 u32 rewrite_length = vec_len (rewrite);
325 ioam_e2e_cache_option_t *e2e = 0;
326 u8 no_of_responses = cm->wait_for_responses;
328 from = vlib_frame_vector_args (frame);
329 n_left_from = frame->n_vectors;
330 next_index = node->cached_next_index;
332 while (n_left_from > 0)
336 vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
338 now = vlib_time_now (vm);
339 while (n_left_from >= 4 && n_left_to_next >= 2)
342 vlib_buffer_t *b0, *b1;
344 ip6_header_t *ip0, *ip1;
345 tcp_header_t *tcp0, *tcp1;
346 u32 tcp_offset0, tcp_offset1;
347 ip6_hop_by_hop_header_t *hbh0, *hbh1;
348 u64 *copy_src0, *copy_dst0, *copy_src1, *copy_dst1;
350 u32 pool_index0 = 0, pool_index1 = 0;
352 next0 = next1 = IP6_IOAM_CACHE_TS_INPUT_NEXT_IP6_LOOKUP;
353 /* Prefetch next iteration. */
355 vlib_buffer_t *p2, *p3;
357 p2 = vlib_get_buffer (vm, from[2]);
358 p3 = vlib_get_buffer (vm, from[3]);
360 vlib_prefetch_buffer_header (p2, LOAD);
361 vlib_prefetch_buffer_header (p3, LOAD);
362 CLIB_PREFETCH (p2->data, 2 * CLIB_CACHE_LINE_BYTES, LOAD);
363 CLIB_PREFETCH (p3->data, 2 * CLIB_CACHE_LINE_BYTES, LOAD);
367 /* speculatively enqueue b0 to the current next frame */
368 to_next[0] = bi0 = from[0];
369 to_next[1] = bi1 = from[1];
375 b0 = vlib_get_buffer (vm, bi0);
376 b1 = vlib_get_buffer (vm, bi1);
378 ip0 = vlib_buffer_get_current (b0);
379 ip1 = vlib_buffer_get_current (b1);
381 if (IP_PROTOCOL_TCP !=
382 ip6_locate_header (b0, ip0, IP_PROTOCOL_TCP, &tcp_offset0))
386 tcp0 = (tcp_header_t *) ((u8 *) ip0 + tcp_offset0);
387 if ((tcp0->flags & TCP_FLAG_SYN) == TCP_FLAG_SYN &&
388 (tcp0->flags & TCP_FLAG_ACK) == 0)
390 if (no_of_responses > 0)
392 /* Create TS select entry */
393 if (0 == ioam_cache_ts_add (ip0,
399 (tcp0->seq_number) + 1,
400 no_of_responses, now,
401 vm->cpu_index, &pool_index0))
406 copy_dst0 = (u64 *) (((u8 *) ip0) - rewrite_length);
407 copy_src0 = (u64 *) ip0;
409 copy_dst0[0] = copy_src0[0];
410 copy_dst0[1] = copy_src0[1];
411 copy_dst0[2] = copy_src0[2];
412 copy_dst0[3] = copy_src0[3];
413 copy_dst0[4] = copy_src0[4];
415 vlib_buffer_advance (b0, -(word) rewrite_length);
416 ip0 = vlib_buffer_get_current (b0);
418 hbh0 = (ip6_hop_by_hop_header_t *) (ip0 + 1);
419 /* $$$ tune, rewrite_length is a multiple of 8 */
420 clib_memcpy (hbh0, rewrite, rewrite_length);
422 (ioam_e2e_cache_option_t *) ((u8 *) hbh0 +
423 cm->rewrite_pool_index_offset);
424 e2e->pool_id = (u8) vm->cpu_index;
425 e2e->pool_index = pool_index0;
426 ioam_e2e_id_rewrite_handler ((ioam_e2e_id_option_t *)
428 sizeof (ioam_e2e_cache_option_t)),
430 /* Patch the protocol chain, insert the h-b-h (type 0) header */
431 hbh0->protocol = ip0->protocol;
434 clib_net_to_host_u16 (ip0->payload_length) + rewrite_length;
435 ip0->payload_length = clib_host_to_net_u16 (new_l0);
440 if (IP_PROTOCOL_TCP !=
441 ip6_locate_header (b1, ip1, IP_PROTOCOL_TCP, &tcp_offset1))
445 tcp1 = (tcp_header_t *) ((u8 *) ip1 + tcp_offset1);
446 if ((tcp1->flags & TCP_FLAG_SYN) == TCP_FLAG_SYN &&
447 (tcp1->flags & TCP_FLAG_ACK) == 0)
449 if (no_of_responses > 0)
451 /* Create TS select entry */
452 if (0 == ioam_cache_ts_add (ip1,
458 (tcp1->seq_number) + 1,
459 no_of_responses, now,
460 vm->cpu_index, &pool_index1))
466 copy_dst1 = (u64 *) (((u8 *) ip1) - rewrite_length);
467 copy_src1 = (u64 *) ip1;
469 copy_dst1[0] = copy_src1[0];
470 copy_dst1[1] = copy_src1[1];
471 copy_dst1[2] = copy_src1[2];
472 copy_dst1[3] = copy_src1[3];
473 copy_dst1[4] = copy_src1[4];
475 vlib_buffer_advance (b1, -(word) rewrite_length);
476 ip1 = vlib_buffer_get_current (b1);
478 hbh1 = (ip6_hop_by_hop_header_t *) (ip1 + 1);
479 /* $$$ tune, rewrite_length is a multiple of 8 */
480 clib_memcpy (hbh1, rewrite, rewrite_length);
482 (ioam_e2e_cache_option_t *) ((u8 *) hbh1 +
483 cm->rewrite_pool_index_offset);
484 e2e->pool_id = (u8) vm->cpu_index;
485 e2e->pool_index = pool_index1;
486 ioam_e2e_id_rewrite_handler ((ioam_e2e_id_option_t *)
488 sizeof (ioam_e2e_cache_option_t)),
490 /* Patch the protocol chain, insert the h-b-h (type 0) header */
491 hbh1->protocol = ip1->protocol;
494 clib_net_to_host_u16 (ip1->payload_length) + rewrite_length;
495 ip1->payload_length = clib_host_to_net_u16 (new_l1);
500 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
502 if (b0->flags & VLIB_BUFFER_IS_TRACED)
504 ip6_reset_ts_hbh_trace_t *t =
505 vlib_add_trace (vm, node, b0, sizeof (*t));
506 t->next_index = next0;
508 if (b1->flags & VLIB_BUFFER_IS_TRACED)
510 ip6_reset_ts_hbh_trace_t *t =
511 vlib_add_trace (vm, node, b1, sizeof (*t));
512 t->next_index = next1;
517 /* verify speculative enqueue, maybe switch current next frame */
518 vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
519 to_next, n_left_to_next,
520 bi0, bi1, next0, next1);
522 while (n_left_from > 0 && n_left_to_next > 0)
530 ip6_hop_by_hop_header_t *hbh0;
531 u64 *copy_src0, *copy_dst0;
535 next0 = IP6_IOAM_CACHE_TS_INPUT_NEXT_IP6_LOOKUP;
536 /* speculatively enqueue b0 to the current next frame */
544 b0 = vlib_get_buffer (vm, bi0);
546 ip0 = vlib_buffer_get_current (b0);
547 if (IP_PROTOCOL_TCP !=
548 ip6_locate_header (b0, ip0, IP_PROTOCOL_TCP, &tcp_offset0))
552 tcp0 = (tcp_header_t *) ((u8 *) ip0 + tcp_offset0);
553 if ((tcp0->flags & TCP_FLAG_SYN) == TCP_FLAG_SYN &&
554 (tcp0->flags & TCP_FLAG_ACK) == 0)
556 if (no_of_responses > 0)
558 /* Create TS select entry */
559 if (0 == ioam_cache_ts_add (ip0,
565 (tcp0->seq_number) + 1,
566 no_of_responses, now,
567 vm->cpu_index, &pool_index0))
572 copy_dst0 = (u64 *) (((u8 *) ip0) - rewrite_length);
573 copy_src0 = (u64 *) ip0;
575 copy_dst0[0] = copy_src0[0];
576 copy_dst0[1] = copy_src0[1];
577 copy_dst0[2] = copy_src0[2];
578 copy_dst0[3] = copy_src0[3];
579 copy_dst0[4] = copy_src0[4];
581 vlib_buffer_advance (b0, -(word) rewrite_length);
582 ip0 = vlib_buffer_get_current (b0);
584 hbh0 = (ip6_hop_by_hop_header_t *) (ip0 + 1);
585 /* $$$ tune, rewrite_length is a multiple of 8 */
586 clib_memcpy (hbh0, rewrite, rewrite_length);
588 (ioam_e2e_cache_option_t *) ((u8 *) hbh0 +
589 cm->rewrite_pool_index_offset);
590 e2e->pool_id = (u8) vm->cpu_index;
591 e2e->pool_index = pool_index0;
592 ioam_e2e_id_rewrite_handler ((ioam_e2e_id_option_t *)
594 sizeof (ioam_e2e_cache_option_t)),
596 /* Patch the protocol chain, insert the h-b-h (type 0) header */
597 hbh0->protocol = ip0->protocol;
600 clib_net_to_host_u16 (ip0->payload_length) + rewrite_length;
601 ip0->payload_length = clib_host_to_net_u16 (new_l0);
605 if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
606 && (b0->flags & VLIB_BUFFER_IS_TRACED)))
608 ip6_reset_ts_hbh_trace_t *t =
609 vlib_add_trace (vm, node, b0, sizeof (*t));
610 t->next_index = next0;
613 /* verify speculative enqueue, maybe switch current next frame */
614 vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
615 to_next, n_left_to_next,
619 vlib_put_next_frame (vm, node, next_index, n_left_to_next);
622 vlib_node_increment_counter (vm, ip6_reset_ts_hbh_node.index,
623 IP6_RESET_TS_HBH_ERROR_PROCESSED, processed);
624 vlib_node_increment_counter (vm, ip6_reset_ts_hbh_node.index,
625 IP6_RESET_TS_HBH_ERROR_SAVED, cache_ts_added);
627 return frame->n_vectors;
631 VLIB_REGISTER_NODE (ip6_reset_ts_hbh_node) =
633 .function = ip6_reset_ts_hbh_node_fn,
634 .name = "ip6-add-syn-hop-by-hop",
635 .vector_size = sizeof (u32),
636 .format_trace = format_ip6_reset_ts_hbh_trace,
637 .type = VLIB_NODE_TYPE_INTERNAL,
638 .n_errors = ARRAY_LEN (ip6_reset_ts_hbh_error_strings),
639 .error_strings = ip6_reset_ts_hbh_error_strings,
640 /* See ip/lookup.h */
641 .n_next_nodes = IP6_IOAM_CACHE_TS_INPUT_N_NEXT,
644 #define _(s,n) [IP6_IOAM_CACHE_TS_INPUT_NEXT_##s] = n,
645 foreach_ip6_ioam_cache_ts_input_next
650 VLIB_NODE_FUNCTION_MULTIARCH (ip6_reset_ts_hbh_node, ip6_reset_ts_hbh_node_fn)
653 vlib_node_registration_t ioam_cache_ts_timer_tick_node;
658 } ioam_cache_ts_timer_tick_trace_t;
660 /* packet trace format function */
662 format_ioam_cache_ts_timer_tick_trace (u8 * s, va_list * args)
664 CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
665 CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
666 ioam_cache_ts_timer_tick_trace_t *t =
667 va_arg (*args, ioam_cache_ts_timer_tick_trace_t *);
669 s = format (s, "IOAM_CACHE_TS_TIMER_TICK: thread index %d",
674 #define foreach_ioam_cache_ts_timer_tick_error \
675 _(TIMER, "Timer events")
679 #define _(sym,str) IOAM_CACHE_TS_TIMER_TICK_ERROR_##sym,
680 foreach_ioam_cache_ts_timer_tick_error
682 IOAM_CACHE_TS_TIMER_TICK_N_ERROR,
683 } ioam_cache_ts_timer_tick_error_t;
685 static char *ioam_cache_ts_timer_tick_error_strings[] = {
686 #define _(sym,string) string,
687 foreach_ioam_cache_ts_timer_tick_error
692 ioam_cache_ts_timer_node_enable (vlib_main_t * vm, u8 enable)
694 vlib_node_set_state (vm, ioam_cache_ts_timer_tick_node.index,
696 0 ? VLIB_NODE_STATE_DISABLED :
697 VLIB_NODE_STATE_POLLING);
701 expired_cache_ts_timer_callback (u32 * expired_timers)
703 ioam_cache_main_t *cm = &ioam_cache_main;
706 u32 thread_index = os_get_cpu_number ();
709 for (i = 0; i < vec_len (expired_timers); i++)
711 /* Get pool index and pool id */
712 pool_index = expired_timers[i] & 0x0FFFFFFF;
714 /* Handle expiration */
715 ioam_cache_ts_send (thread_index, pool_index);
718 vlib_node_increment_counter (cm->vlib_main,
719 ioam_cache_ts_timer_tick_node.index,
720 IOAM_CACHE_TS_TIMER_TICK_ERROR_TIMER, count);
724 ioam_cache_ts_timer_tick_node_fn (vlib_main_t * vm,
725 vlib_node_runtime_t * node,
728 ioam_cache_main_t *cm = &ioam_cache_main;
729 u32 my_thread_index = os_get_cpu_number ();
730 struct timespec ts, tsrem;
732 tw_timer_expire_timers_16t_2w_512sl (&cm->timer_wheels[my_thread_index],
735 ts.tv_nsec = 1000 * 1000 * IOAM_CACHE_TS_TICK;
736 while (nanosleep (&ts, &tsrem) < 0)
744 VLIB_REGISTER_NODE (ioam_cache_ts_timer_tick_node) = {
745 .function = ioam_cache_ts_timer_tick_node_fn,
746 .name = "ioam-cache-ts-timer-tick",
747 .format_trace = format_ioam_cache_ts_timer_tick_trace,
748 .type = VLIB_NODE_TYPE_INPUT,
750 .n_errors = ARRAY_LEN(ioam_cache_ts_timer_tick_error_strings),
751 .error_strings = ioam_cache_ts_timer_tick_error_strings,
755 .state = VLIB_NODE_STATE_DISABLED,
757 /* edit / add dispositions here */
765 * fd.io coding-style-patch-verification: ON
768 * eval: (c-set-style "gnu")