xref: /mOS-networking-stack/core/src/tcp_out.c (revision 152f7c19)
1 #include <unistd.h>
2 #include <string.h>
3 
4 #include "tcp_out.h"
5 #include "mtcp.h"
6 #include "ip_in.h"
7 #include "ip_out.h"
8 #include "tcp_in.h"
9 #include "tcp.h"
10 #include "tcp_stream.h"
11 #include "eventpoll.h"
12 #include "timer.h"
13 #include "debug.h"
14 #include "config.h"
15 
16 #define TCP_CALCULATE_CHECKSUM		TRUE
17 #define ACK_PIGGYBACK			TRUE
18 /* Enable this for higher concurrency rate experiments */
19 #define TRY_SEND_BEFORE_QUEUE		/*FALSE*/ TRUE
20 
21 #define TCP_MAX_WINDOW 65535
22 
23 #define MAX(a, b) ((a)>(b)?(a):(b))
24 #define MIN(a, b) ((a)<(b)?(a):(b))
25 
26 /*----------------------------------------------------------------------------*/
27 static inline uint16_t
28 CalculateOptionLength(uint8_t flags)
29 {
30 	uint16_t optlen = 0;
31 
32 	if (flags & TCP_FLAG_SYN) {
33 		optlen += TCP_OPT_MSS_LEN;
34 #if TCP_OPT_SACK_ENABLED
35 		optlen += TCP_OPT_SACK_PERMIT_LEN;
36 #if !TCP_OPT_TIMESTAMP_ENABLED
37 		optlen += 2;	// insert NOP padding
38 #endif /* TCP_OPT_TIMESTAMP_ENABLED */
39 #endif /* TCP_OPT_SACK_ENABLED */
40 
41 #if TCP_OPT_TIMESTAMP_ENABLED
42 		optlen += TCP_OPT_TIMESTAMP_LEN;
43 #if !TCP_OPT_SACK_ENABLED
44 		optlen += 2;	// insert NOP padding
45 #endif /* TCP_OPT_SACK_ENABLED */
46 #endif /* TCP_OPT_TIMESTAMP_ENABLED */
47 
48 		optlen += TCP_OPT_WSCALE_LEN + 1;
49 
50 	} else {
51 
52 #if TCP_OPT_TIMESTAMP_ENABLED
53 		optlen += TCP_OPT_TIMESTAMP_LEN + 2;
54 #endif
55 
56 #if TCP_OPT_SACK_ENABLED
57 		if (flags & TCP_FLAG_SACK) {
58 			optlen += TCP_OPT_SACK_LEN + 2;
59 		}
60 #endif
61 	}
62 
63 	assert(optlen % 4 == 0);
64 
65 	return optlen;
66 }
67 /*----------------------------------------------------------------------------*/
68 static inline void
69 GenerateTCPTimestamp(tcp_stream *cur_stream, uint8_t *tcpopt, uint32_t cur_ts)
70 {
71 	uint32_t *ts = (uint32_t *)(tcpopt + 2);
72 
73 	tcpopt[0] = TCP_OPT_TIMESTAMP;
74 	tcpopt[1] = TCP_OPT_TIMESTAMP_LEN;
75 	ts[0] = htonl(cur_ts);
76 	ts[1] = htonl(cur_stream->rcvvar->ts_recent);
77 }
78 /*----------------------------------------------------------------------------*/
79 static inline void
80 GenerateTCPOptions(tcp_stream *cur_stream, uint32_t cur_ts,
81 		uint8_t flags, uint8_t *tcpopt, uint16_t optlen)
82 {
83 	int i = 0;
84 
85 	if (flags & TCP_FLAG_SYN) {
86 		uint16_t mss;
87 
88 		/* MSS option */
89 		mss = cur_stream->sndvar->mss;
90 		tcpopt[i++] = TCP_OPT_MSS;
91 		tcpopt[i++] = TCP_OPT_MSS_LEN;
92 		tcpopt[i++] = mss >> 8;
93 		tcpopt[i++] = mss % 256;
94 
95 		/* SACK permit */
96 #if TCP_OPT_SACK_ENABLED
97 #if !TCP_OPT_TIMESTAMP_ENABLED
98 		tcpopt[i++] = TCP_OPT_NOP;
99 		tcpopt[i++] = TCP_OPT_NOP;
100 #endif /* TCP_OPT_TIMESTAMP_ENABLED */
101 		tcpopt[i++] = TCP_OPT_SACK_PERMIT;
102 		tcpopt[i++] = TCP_OPT_SACK_PERMIT_LEN;
103 		TRACE_SACK("Local SACK permited.\n");
104 #endif /* TCP_OPT_SACK_ENABLED */
105 
106 		/* Timestamp */
107 #if TCP_OPT_TIMESTAMP_ENABLED
108 #if !TCP_OPT_SACK_ENABLED
109 		tcpopt[i++] = TCP_OPT_NOP;
110 		tcpopt[i++] = TCP_OPT_NOP;
111 #endif /* TCP_OPT_SACK_ENABLED */
112 		GenerateTCPTimestamp(cur_stream, tcpopt + i, cur_ts);
113 		i += TCP_OPT_TIMESTAMP_LEN;
114 #endif /* TCP_OPT_TIMESTAMP_ENABLED */
115 
116 		/* Window scale */
117 		tcpopt[i++] = TCP_OPT_NOP;
118 		tcpopt[i++] = TCP_OPT_WSCALE;
119 		tcpopt[i++] = TCP_OPT_WSCALE_LEN;
120 		tcpopt[i++] = cur_stream->sndvar->wscale_mine;
121 
122 	} else {
123 
124 #if TCP_OPT_TIMESTAMP_ENABLED
125 		tcpopt[i++] = TCP_OPT_NOP;
126 		tcpopt[i++] = TCP_OPT_NOP;
127 		GenerateTCPTimestamp(cur_stream, tcpopt + i, cur_ts);
128 		i += TCP_OPT_TIMESTAMP_LEN;
129 #endif
130 
131 #if TCP_OPT_SACK_ENABLED
132 		if (flags & TCP_OPT_SACK) {
133 			// TODO: implement SACK support
134 		}
135 #endif
136 	}
137 
138 	assert (i == optlen);
139 }
140 /*----------------------------------------------------------------------------*/
141 int
142 SendTCPPacketStandalone(struct mtcp_manager *mtcp,
143 		uint32_t saddr, uint16_t sport, uint32_t daddr, uint16_t dport,
144 		uint32_t seq, uint32_t ack_seq, uint16_t window, uint8_t flags,
145 		uint8_t *payload, uint16_t payloadlen,
146 		uint32_t cur_ts, uint32_t echo_ts, uint16_t ip_id, int8_t in_ifidx)
147 {
148 	struct tcphdr *tcph;
149 	uint8_t *tcpopt;
150 	uint32_t *ts;
151 	uint16_t optlen;
152 	struct pkt_ctx pctx;
153 	int rc = -1;
154 
155 	memset(&pctx, 0, sizeof(pctx));
156 	pctx.p.in_ifidx = in_ifidx;
157 	optlen = CalculateOptionLength(flags);
158 	if (payloadlen > TCP_DEFAULT_MSS + optlen) {
159 		TRACE_ERROR("Payload size exceeds MSS.\n");
160 		assert(0);
161 		return ERROR;
162 	}
163 
164 	tcph = (struct tcphdr *)IPOutputStandalone(mtcp, htons(ip_id),
165 			saddr, daddr, TCP_HEADER_LEN + optlen + payloadlen, &pctx, cur_ts);
166 	if (tcph == NULL) {
167 		return ERROR;
168 	}
169 	memset(tcph, 0, TCP_HEADER_LEN + optlen);
170 
171 	tcph->source = sport;
172 	tcph->dest = dport;
173 
174 	if (flags & TCP_FLAG_SYN)
175 		tcph->syn = TRUE;
176 	if (flags & TCP_FLAG_FIN)
177 		tcph->fin = TRUE;
178 	if (flags & TCP_FLAG_RST)
179 		tcph->rst = TRUE;
180 	if (flags & TCP_FLAG_PSH)
181 		tcph->psh = TRUE;
182 
183 	tcph->seq = htonl(seq);
184 	if (flags & TCP_FLAG_ACK) {
185 		tcph->ack = TRUE;
186 		tcph->ack_seq = htonl(ack_seq);
187 	}
188 
189 	tcph->window = htons(MIN(window, TCP_MAX_WINDOW));
190 
191 	tcpopt = (uint8_t *)tcph + TCP_HEADER_LEN;
192 	ts = (uint32_t *)(tcpopt + 4);
193 
194 	tcpopt[0] = TCP_OPT_NOP;
195 	tcpopt[1] = TCP_OPT_NOP;
196 	tcpopt[2] = TCP_OPT_TIMESTAMP;
197 	tcpopt[3] = TCP_OPT_TIMESTAMP_LEN;
198 	ts[0] = htonl(cur_ts);
199 	ts[1] = htonl(echo_ts);
200 
201 	tcph->doff = (TCP_HEADER_LEN + optlen) >> 2;
202 	// copy payload if exist
203 	if (payloadlen > 0) {
204 		memcpy((uint8_t *)tcph + TCP_HEADER_LEN + optlen, payload, payloadlen);
205 	}
206 
207 #if TCP_CALCULATE_CHECKSUM
208 	/* offload TCP checkum if possible */
209 	if (likely(mtcp->iom->dev_ioctl != NULL))
210 		rc = mtcp->iom->dev_ioctl(mtcp->ctx,
211 					  pctx.out_ifidx,
212 					  PKT_TX_TCP_CSUM,
213 					  pctx.p.iph);
214 	/* otherwise calculate TCP checksum in S/W */
215 	if (rc == -1)
216 		tcph->check = TCPCalcChecksum((uint16_t *)tcph,
217 					      TCP_HEADER_LEN +
218 					      optlen + payloadlen,
219 					      saddr, daddr);
220 #endif
221 
222 	if (tcph->syn || tcph->fin) {
223 		payloadlen++;
224 	}
225 
226 	struct mon_listener *walk;
227 	/* callback for monitor raw socket */
228 	TAILQ_FOREACH(walk, &mtcp->monitors, link)
229 		if (walk->socket->socktype == MOS_SOCK_MONITOR_RAW)
230 			HandleCallback(mtcp, MOS_NULL, walk->socket, MOS_SIDE_BOTH,
231 				       &pctx, MOS_ON_PKT_IN);
232 	return payloadlen;
233 }
234 /*----------------------------------------------------------------------------*/
235 int
236 SendTCPPacket(struct mtcp_manager *mtcp, tcp_stream *cur_stream,
237 		uint32_t cur_ts, uint8_t flags, uint8_t *payload, uint16_t payloadlen)
238 {
239 	struct tcphdr *tcph;
240 	uint16_t optlen;
241 	uint8_t wscale = 0;
242 	uint32_t window32 = 0;
243 	struct pkt_ctx pctx;
244 	int rc = -1;
245 
246 	memset(&pctx, 0, sizeof(pctx));
247 	optlen = CalculateOptionLength(flags);
248 	if (payloadlen > cur_stream->sndvar->mss + optlen) {
249 		TRACE_ERROR("Payload size exceeds MSS\n");
250 		return ERROR;
251 	}
252 
253 	tcph = (struct tcphdr *)IPOutput(mtcp, cur_stream,
254 			TCP_HEADER_LEN + optlen + payloadlen, &pctx, cur_ts);
255 	if (tcph == NULL) {
256 		return -2;
257 	}
258 	memset(tcph, 0, TCP_HEADER_LEN + optlen);
259 
260 	tcph->source = cur_stream->sport;
261 	tcph->dest = cur_stream->dport;
262 
263 	if (flags & TCP_FLAG_SYN) {
264 		tcph->syn = TRUE;
265 		if (cur_stream->snd_nxt != cur_stream->sndvar->iss) {
266 			TRACE_DBG("Stream %d: weird SYN sequence. "
267 					"snd_nxt: %u, iss: %u\n", cur_stream->id,
268 					cur_stream->snd_nxt, cur_stream->sndvar->iss);
269 		}
270 		TRACE_DBG("Stream %d: Sending SYN. seq: %u, ack_seq: %u\n",
271 			  cur_stream->id, cur_stream->snd_nxt, cur_stream->rcv_nxt);
272 	}
273 	if (flags & TCP_FLAG_RST) {
274 		TRACE_FIN("Stream %d: Sending RST.\n", cur_stream->id);
275 		tcph->rst = TRUE;
276 	}
277 	if (flags & TCP_FLAG_PSH)
278 		tcph->psh = TRUE;
279 
280 	if (flags & TCP_FLAG_WACK) {
281 		tcph->seq = htonl(cur_stream->snd_nxt - 1);
282 		TRACE_CLWND("%u Sending ACK to get new window advertisement. "
283 				"seq: %u, peer_wnd: %u, snd_nxt - snd_una: %u\n",
284 				cur_stream->id,
285 				cur_stream->snd_nxt - 1, cur_stream->sndvar->peer_wnd,
286 				cur_stream->snd_nxt - cur_stream->sndvar->snd_una);
287 	} else if (flags & TCP_FLAG_FIN) {
288 		tcph->fin = TRUE;
289 
290 		if (cur_stream->sndvar->fss == 0) {
291 			TRACE_ERROR("Stream %u: not fss set. closed: %u\n",
292 					cur_stream->id, cur_stream->closed);
293 		}
294 		tcph->seq = htonl(cur_stream->sndvar->fss);
295 		cur_stream->sndvar->is_fin_sent = TRUE;
296 		TRACE_FIN("Stream %d: Sending FIN. seq: %u, ack_seq: %u\n",
297 				cur_stream->id, cur_stream->snd_nxt, cur_stream->rcv_nxt);
298 	} else {
299 		tcph->seq = htonl(cur_stream->snd_nxt);
300 	}
301 
302 	if (flags & TCP_FLAG_ACK) {
303 		tcph->ack = TRUE;
304 		tcph->ack_seq = htonl(cur_stream->rcv_nxt);
305 		cur_stream->sndvar->ts_lastack_sent = cur_ts;
306 		cur_stream->last_active_ts = cur_ts;
307 		UpdateTimeoutList(mtcp, cur_stream);
308 	}
309 
310 	if (flags & TCP_FLAG_SYN) {
311 		wscale = 0;
312 	} else {
313 		wscale = cur_stream->sndvar->wscale_mine;
314 	}
315 
316 	window32 = cur_stream->rcvvar->rcv_wnd >> wscale;
317 	tcph->window = htons((uint16_t)MIN(window32, TCP_MAX_WINDOW));
318 	/* if the advertised window is 0, we need to advertise again later */
319 	if (window32 == 0) {
320 		cur_stream->need_wnd_adv = TRUE;
321 	}
322 
323 	GenerateTCPOptions(cur_stream, cur_ts, flags,
324 			(uint8_t *)tcph + TCP_HEADER_LEN, optlen);
325 
326 	tcph->doff = (TCP_HEADER_LEN + optlen) >> 2;
327 	// copy payload if exist
328 	if (payloadlen > 0) {
329 		memcpy((uint8_t *)tcph + TCP_HEADER_LEN + optlen, payload, payloadlen);
330 	}
331 
332 #if TCP_CALCULATE_CHECKSUM
333 	if (likely(mtcp->iom->dev_ioctl != NULL))
334 		rc = mtcp->iom->dev_ioctl(mtcp->ctx,
335 					  pctx.out_ifidx,
336 					  PKT_TX_TCP_CSUM,
337 					  pctx.p.iph);
338 	if (rc == -1)
339 		tcph->check = TCPCalcChecksum((uint16_t *)tcph,
340 					      TCP_HEADER_LEN +
341 					      optlen + payloadlen,
342 					      cur_stream->saddr,
343 					      cur_stream->daddr);
344 #endif
345 	cur_stream->snd_nxt += payloadlen;
346 
347 	if (tcph->syn || tcph->fin) {
348 		cur_stream->snd_nxt++;
349 		payloadlen++;
350 	}
351 
352 	if (payloadlen > 0) {
353 		if (cur_stream->state > TCP_ST_ESTABLISHED) {
354 			TRACE_FIN("Payload after ESTABLISHED: length: %d, snd_nxt: %u\n",
355 				  payloadlen, cur_stream->snd_nxt);
356 		}
357 
358 		/* update retransmission timer if have payload */
359 		cur_stream->sndvar->ts_rto = cur_ts + cur_stream->sndvar->rto;
360 		TRACE_RTO("Updating retransmission timer. "
361 				"cur_ts: %u, rto: %u, ts_rto: %u\n",
362 				cur_ts, cur_stream->sndvar->rto, cur_stream->sndvar->ts_rto);
363 		AddtoRTOList(mtcp, cur_stream);
364 	}
365 
366 	struct mon_listener *walk;
367 	/* callback for monitor raw socket */
368 	TAILQ_FOREACH(walk, &mtcp->monitors, link)
369 		if (walk->socket->socktype == MOS_SOCK_MONITOR_RAW)
370 			HandleCallback(mtcp, MOS_NULL, walk->socket, MOS_SIDE_BOTH,
371 				       &pctx, MOS_ON_PKT_IN);
372 
373 	if (mtcp->num_msp /* this means that stream monitor is on */) {
374 		FillPacketContextTCPInfo(&pctx, tcph);
375 
376 		/* New abstraction for monitor stream */
377 		struct tcp_stream *recvside_stream = cur_stream->pair_stream;
378 		struct tcp_stream *sendside_stream = cur_stream;
379 
380 		if (recvside_stream) {
381 			if (recvside_stream->rcvvar && recvside_stream->rcvvar->rcvbuf)
382 				pctx.p.offset = (uint64_t)seq2loff(recvside_stream->rcvvar->rcvbuf,
383 								   pctx.p.seq, recvside_stream->rcvvar->irs + 1);
384 
385 			UpdateMonitor(mtcp, sendside_stream, recvside_stream, &pctx, false);
386 		}
387 	}
388 
389 #ifdef PKTDUMP
390 	DumpPacket(mtcp,
391 			(char *)tcph - sizeof(struct iphdr) - sizeof(struct ethhdr),
392 			payloadlen + sizeof(struct iphdr) + sizeof(struct ethhdr),
393 			"OUT", -1);
394 #endif
395 
396 
397 	return payloadlen;
398 }
399 /*----------------------------------------------------------------------------*/
400 static int
401 FlushTCPSendingBuffer(mtcp_manager_t mtcp, tcp_stream *cur_stream, uint32_t cur_ts)
402 {
403 	struct tcp_send_vars *sndvar = cur_stream->sndvar;
404 	const uint32_t maxlen = sndvar->mss - CalculateOptionLength(TCP_FLAG_ACK);
405 	uint8_t *data;
406 	uint32_t buffered_len;
407 	uint32_t seq;
408 	uint16_t len;
409 	int16_t sndlen;
410 	uint32_t window;
411 	int packets = 0;
412 
413 	if (!sndvar->sndbuf) {
414 		TRACE_ERROR("Stream %d: No send buffer available.\n", cur_stream->id);
415 		assert(0);
416 		return 0;
417 	}
418 
419 	SBUF_LOCK(&sndvar->write_lock);
420 
421 	if (sndvar->sndbuf->len == 0) {
422 		packets = 0;
423 		goto out;
424 	}
425 
426 	window = MIN(sndvar->cwnd, sndvar->peer_wnd);
427 
428 	while (1) {
429 		seq = cur_stream->snd_nxt;
430 
431 		if (TCP_SEQ_LT(seq, sndvar->sndbuf->head_seq)) {
432 			TRACE_ERROR("Stream %d: Invalid sequence to send. "
433 					"state: %s, seq: %u, head_seq: %u.\n",
434 					cur_stream->id, TCPStateToString(cur_stream),
435 					seq, sndvar->sndbuf->head_seq);
436 			assert(0);
437 			break;
438 		}
439 		buffered_len = sndvar->sndbuf->head_seq + sndvar->sndbuf->len - seq;
440 		if (cur_stream->state > TCP_ST_ESTABLISHED) {
441 			TRACE_FIN("head_seq: %u, len: %u, seq: %u, "
442 					"buffered_len: %u\n", sndvar->sndbuf->head_seq,
443 					sndvar->sndbuf->len, seq, buffered_len);
444 		}
445 		if (buffered_len == 0)
446 			break;
447 
448 		data = sndvar->sndbuf->head +
449 				(seq - sndvar->sndbuf->head_seq);
450 
451 		if (buffered_len > maxlen) {
452 			len = maxlen;
453 		} else {
454 			len = buffered_len;
455 		}
456 
457 		if (len <= 0)
458 			break;
459 
460 		if (cur_stream->state > TCP_ST_ESTABLISHED) {
461 			TRACE_FIN("Flushing after ESTABLISHED: seq: %u, len: %u, "
462 					"buffered_len: %u\n", seq, len, buffered_len);
463 		}
464 
465 		if (seq - sndvar->snd_una + len > window) {
466 			/* Ask for new window advertisement to peer */
467 			if (seq - sndvar->snd_una + len > sndvar->peer_wnd) {
468 				TRACE_DBG("Full peer window. "
469 					  "peer_wnd: %u, (snd_nxt-snd_una): %u\n",
470 					  sndvar->peer_wnd, seq - sndvar->snd_una);
471 				if (TS_TO_MSEC(cur_ts - sndvar->ts_lastack_sent) > 500) {
472 					EnqueueACK(mtcp, cur_stream, cur_ts, ACK_OPT_WACK);
473 				}
474 			}
475 			packets = -3;
476 			goto out;
477 		}
478 
479 		sndlen = SendTCPPacket(mtcp, cur_stream, cur_ts,
480 				TCP_FLAG_ACK, data, len);
481 		if (sndlen < 0) {
482 			packets = sndlen;
483 			goto out;
484 		}
485 		packets++;
486 	}
487 
488  out:
489 	SBUF_UNLOCK(&sndvar->write_lock);
490 	return packets;
491 }
492 /*----------------------------------------------------------------------------*/
493 static inline int
494 SendControlPacket(mtcp_manager_t mtcp, tcp_stream *cur_stream, uint32_t cur_ts)
495 {
496 	struct tcp_send_vars *sndvar = cur_stream->sndvar;
497 	int ret = 0;
498     int flag = 0;
499 
500     switch (cur_stream->state) {
501        case TCP_ST_SYN_SENT: 		/* Send SYN here */
502           flag = TCP_FLAG_SYN;
503           break;
504        case TCP_ST_SYN_RCVD:        /* Send SYN/ACK here */
505           cur_stream->snd_nxt = sndvar->iss;
506           flag = TCP_FLAG_SYN | TCP_FLAG_ACK;
507           break;
508        case TCP_ST_ESTABLISHED:     /* Send ACK here */
509        case TCP_ST_CLOSE_WAIT:	    /* Send ACK for the FIN here */
510        case TCP_ST_FIN_WAIT_2:      /* Send ACK here */
511        case TCP_ST_TIME_WAIT:       /* Send ACK here */
512           flag = TCP_FLAG_ACK;
513           break;
514        case TCP_ST_LAST_ACK:
515        case TCP_ST_FIN_WAIT_1:
516           /* if it is on ack_list, send it after sending ack */
517           if (sndvar->on_send_list || sndvar->on_ack_list)
518              return (-1);
519           flag = TCP_FLAG_FIN | TCP_FLAG_ACK; /* Send FIN/ACK here */
520           break;
521        case TCP_ST_CLOSING:
522           if (sndvar->is_fin_sent) {
523              /* if the sequence is for FIN, send FIN */
524              flag = (cur_stream->snd_nxt == sndvar->fss) ?
525                 (TCP_FLAG_FIN | TCP_FLAG_ACK) : TCP_FLAG_ACK;
526           } else {
527              /* if FIN is not sent, send fin with ack */
528              flag = TCP_FLAG_FIN | TCP_FLAG_ACK;
529           }
530        case TCP_ST_CLOSED_RSVD: /* Send RST here */
531           TRACE_DBG("Stream %d: Try sending RST (TCP_ST_CLOSED_RSVD)\n",
532                     cur_stream->id);
533           /* first flush the data and ack */
534           if (sndvar->on_send_list || sndvar->on_ack_list)
535              return (-1);
536           ret = SendTCPPacket(mtcp, cur_stream, cur_ts, TCP_FLAG_RST, NULL, 0);
537           if (ret >= 0)
538              DestroyTCPStream(mtcp, cur_stream);
539           return (ret);
540        default:
541           TRACE_ERROR("Stream %d: shouldn't send a control packet\n",
542                       cur_stream->id);
543           assert(0); /* can't reach here! */
544           return (0);
545     }
546 
547     return SendTCPPacket(mtcp, cur_stream, cur_ts, flag, NULL, 0);
548 }
549 /*----------------------------------------------------------------------------*/
550 inline int
551 WriteTCPControlList(mtcp_manager_t mtcp,
552 		struct mtcp_sender *sender, uint32_t cur_ts, int thresh)
553 {
554 	tcp_stream *cur_stream;
555 	tcp_stream *next, *last;
556 	int cnt = 0;
557 	int ret;
558 
559 	thresh = MIN(thresh, sender->control_list_cnt);
560 
561 	/* Send TCP control messages */
562 	cnt = 0;
563 	cur_stream = TAILQ_FIRST(&sender->control_list);
564 	last = TAILQ_LAST(&sender->control_list, control_head);
565 	while (cur_stream) {
566 		if (++cnt > thresh)
567 			break;
568 
569 		TRACE_LOOP("Inside control loop. cnt: %u, stream: %d\n",
570 				cnt, cur_stream->id);
571 		next = TAILQ_NEXT(cur_stream, sndvar->control_link);
572 
573 		TAILQ_REMOVE(&sender->control_list, cur_stream, sndvar->control_link);
574 		sender->control_list_cnt--;
575 
576 		if (cur_stream->sndvar->on_control_list) {
577 			cur_stream->sndvar->on_control_list = FALSE;
578 			//TRACE_DBG("Stream %u: Sending control packet\n", cur_stream->id);
579 			ret = SendControlPacket(mtcp, cur_stream, cur_ts);
580 			if (ret < 0) {
581 				TAILQ_INSERT_HEAD(&sender->control_list,
582 						cur_stream, sndvar->control_link);
583 				cur_stream->sndvar->on_control_list = TRUE;
584 				sender->control_list_cnt++;
585 				/* since there is no available write buffer, break */
586 				break;
587 			}
588 		} else {
589 			TRACE_ERROR("Stream %d: not on control list.\n", cur_stream->id);
590 		}
591 
592 		if (cur_stream == last)
593 			break;
594 		cur_stream = next;
595 	}
596 
597 	return cnt;
598 }
599 /*----------------------------------------------------------------------------*/
600 inline int
601 WriteTCPDataList(mtcp_manager_t mtcp,
602 		struct mtcp_sender *sender, uint32_t cur_ts, int thresh)
603 {
604 	tcp_stream *cur_stream;
605 	tcp_stream *next, *last;
606 	int cnt = 0;
607 	int ret;
608 
609 	/* Send data */
610 	cnt = 0;
611 	cur_stream = TAILQ_FIRST(&sender->send_list);
612 	last = TAILQ_LAST(&sender->send_list, send_head);
613 	while (cur_stream) {
614 		if (++cnt > thresh)
615 			break;
616 
617 		TRACE_LOOP("Inside send loop. cnt: %u, stream: %d\n",
618 				cnt, cur_stream->id);
619 		next = TAILQ_NEXT(cur_stream, sndvar->send_link);
620 
621 		TAILQ_REMOVE(&sender->send_list, cur_stream, sndvar->send_link);
622 		if (cur_stream->sndvar->on_send_list) {
623 			ret = 0;
624 
625 			/* Send data here */
626 			/* Only can send data when ESTABLISHED or CLOSE_WAIT */
627 			if (cur_stream->state == TCP_ST_ESTABLISHED) {
628 				if (cur_stream->sndvar->on_control_list) {
629 					/* delay sending data after until on_control_list becomes off */
630 					//TRACE_DBG("Stream %u: delay sending data.\n", cur_stream->id);
631 					ret = -1;
632 				} else {
633 					ret = FlushTCPSendingBuffer(mtcp, cur_stream, cur_ts);
634 				}
635 			} else if (cur_stream->state == TCP_ST_CLOSE_WAIT ||
636 					cur_stream->state == TCP_ST_FIN_WAIT_1 ||
637 					cur_stream->state == TCP_ST_LAST_ACK) {
638 				ret = FlushTCPSendingBuffer(mtcp, cur_stream, cur_ts);
639 			} else {
640 				TRACE_DBG("Stream %d: on_send_list at state %s\n",
641 						cur_stream->id, TCPStateToString(cur_stream));
642 #if DUMP_STREAM
643 				DumpStream(mtcp, cur_stream);
644 #endif
645 			}
646 
647 			if (ret < 0) {
648 				TAILQ_INSERT_TAIL(&sender->send_list, cur_stream, sndvar->send_link);
649 				/* since there is no available write buffer, break */
650 				break;
651 
652 			} else {
653 				cur_stream->sndvar->on_send_list = FALSE;
654 				sender->send_list_cnt--;
655 				/* the ret value is the number of packets sent. */
656 				/* decrease ack_cnt for the piggybacked acks */
657 #if ACK_PIGGYBACK
658 				if (cur_stream->sndvar->ack_cnt > 0) {
659 					if (cur_stream->sndvar->ack_cnt > ret) {
660 						cur_stream->sndvar->ack_cnt -= ret;
661 					} else {
662 						cur_stream->sndvar->ack_cnt = 0;
663 					}
664 				}
665 #endif
666 #if 1
667 				if (cur_stream->control_list_waiting) {
668 					if (!cur_stream->sndvar->on_ack_list) {
669 						cur_stream->control_list_waiting = FALSE;
670 						AddtoControlList(mtcp, cur_stream, cur_ts);
671 					}
672 				}
673 #endif
674 			}
675 		} else {
676 			TRACE_ERROR("Stream %d: not on send list.\n", cur_stream->id);
677 #ifdef DUMP_STREAM
678 			DumpStream(mtcp, cur_stream);
679 #endif
680 		}
681 
682 		if (cur_stream == last)
683 			break;
684 		cur_stream = next;
685 	}
686 
687 	return cnt;
688 }
689 /*----------------------------------------------------------------------------*/
690 inline int
691 WriteTCPACKList(mtcp_manager_t mtcp,
692 		struct mtcp_sender *sender, uint32_t cur_ts, int thresh)
693 {
694 	tcp_stream *cur_stream;
695 	tcp_stream *next, *last;
696 	int to_ack;
697 	int cnt = 0;
698 	int ret;
699 
700 	/* Send aggregated acks */
701 	cnt = 0;
702 	cur_stream = TAILQ_FIRST(&sender->ack_list);
703 	last = TAILQ_LAST(&sender->ack_list, ack_head);
704 	while (cur_stream) {
705 		if (++cnt > thresh)
706 			break;
707 
708 		TRACE_LOOP("Inside ack loop. cnt: %u\n", cnt);
709 		next = TAILQ_NEXT(cur_stream, sndvar->ack_link);
710 
711 		if (cur_stream->sndvar->on_ack_list) {
712 			/* this list is only to ack the data packets */
713 			/* if the ack is not data ack, then it will not process here */
714 			to_ack = FALSE;
715 			if (cur_stream->state == TCP_ST_ESTABLISHED ||
716 					cur_stream->state == TCP_ST_CLOSE_WAIT ||
717 					cur_stream->state == TCP_ST_FIN_WAIT_1 ||
718 					cur_stream->state == TCP_ST_FIN_WAIT_2 ||
719 					cur_stream->state == TCP_ST_TIME_WAIT) {
720 				/* TIMEWAIT is possible since the ack is queued
721 				   at FIN_WAIT_2 */
722 				tcprb_t *rb;
723 				if ((rb = cur_stream->rcvvar->rcvbuf) &&
724 					TCP_SEQ_LEQ(cur_stream->rcv_nxt,
725 						(cur_stream->rcvvar->irs + 1) + rb->pile
726 						+ tcprb_cflen(rb))) {
727 					to_ack = TRUE;
728 				}
729 			} else {
730 				TRACE_DBG("Stream %u (%s): "
731 						"Try sending ack at not proper state. "
732 						"seq: %u, ack_seq: %u, on_control_list: %u\n",
733 						cur_stream->id, TCPStateToString(cur_stream),
734 						cur_stream->snd_nxt, cur_stream->rcv_nxt,
735 						cur_stream->sndvar->on_control_list);
736 #ifdef DUMP_STREAM
737 				DumpStream(mtcp, cur_stream);
738 #endif
739 			}
740 
741 			if (to_ack) {
742 				/* send the queued ack packets */
743 				while (cur_stream->sndvar->ack_cnt > 0) {
744 					ret = SendTCPPacket(mtcp, cur_stream,
745 							cur_ts, TCP_FLAG_ACK, NULL, 0);
746 					if (ret < 0) {
747 						/* since there is no available write buffer, break */
748 						break;
749 					}
750 					cur_stream->sndvar->ack_cnt--;
751 				}
752 
753 				/* if is_wack is set, send packet to get window advertisement */
754 				if (cur_stream->sndvar->is_wack) {
755 					cur_stream->sndvar->is_wack = FALSE;
756 					ret = SendTCPPacket(mtcp, cur_stream,
757 							cur_ts, TCP_FLAG_ACK | TCP_FLAG_WACK, NULL, 0);
758 					if (ret < 0) {
759 						/* since there is no available write buffer, break */
760 						cur_stream->sndvar->is_wack = TRUE;
761 					}
762 				}
763 
764 				if (!(cur_stream->sndvar->ack_cnt || cur_stream->sndvar->is_wack)) {
765 					cur_stream->sndvar->on_ack_list = FALSE;
766 					TAILQ_REMOVE(&sender->ack_list, cur_stream, sndvar->ack_link);
767 					sender->ack_list_cnt--;
768 				}
769 			} else {
770 				cur_stream->sndvar->on_ack_list = FALSE;
771 				cur_stream->sndvar->ack_cnt = 0;
772 				cur_stream->sndvar->is_wack = 0;
773 				TAILQ_REMOVE(&sender->ack_list, cur_stream, sndvar->ack_link);
774 				sender->ack_list_cnt--;
775 			}
776 
777 			if (cur_stream->control_list_waiting) {
778 				if (!cur_stream->sndvar->on_send_list) {
779 					cur_stream->control_list_waiting = FALSE;
780 					AddtoControlList(mtcp, cur_stream, cur_ts);
781 				}
782 			}
783 		} else {
784 			TRACE_ERROR("Stream %d: not on ack list.\n", cur_stream->id);
785 			TAILQ_REMOVE(&sender->ack_list, cur_stream, sndvar->ack_link);
786 			sender->ack_list_cnt--;
787 #ifdef DUMP_STREAM
788 			thread_printf(mtcp, mtcp->log_fp,
789 					"Stream %u: not on ack list.\n", cur_stream->id);
790 			DumpStream(mtcp, cur_stream);
791 #endif
792 		}
793 
794 		if (cur_stream == last)
795 			break;
796 		cur_stream = next;
797 	}
798 
799 	return cnt;
800 }
801 /*----------------------------------------------------------------------------*/
802 inline struct mtcp_sender *
803 GetSender(mtcp_manager_t mtcp, tcp_stream *cur_stream)
804 {
805 	if (cur_stream->sndvar->nif_out < 0) {
806 		return mtcp->g_sender;
807 
808 	} else if (cur_stream->sndvar->nif_out >= g_config.mos->netdev_table->num) {
809 		TRACE_ERROR("(NEVER HAPPEN) Failed to find appropriate sender.\n");
810 		return NULL;
811 
812 	} else {
813 		return mtcp->n_sender[cur_stream->sndvar->nif_out];
814 	}
815 }
816 /*----------------------------------------------------------------------------*/
817 inline void
818 AddtoControlList(mtcp_manager_t mtcp, tcp_stream *cur_stream, uint32_t cur_ts)
819 {
820 #if TRY_SEND_BEFORE_QUEUE
821 	int ret;
822 	struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
823 	assert(sender != NULL);
824 
825 	ret = SendControlPacket(mtcp, cur_stream, cur_ts);
826 	if (ret < 0) {
827 #endif
828 		if (!cur_stream->sndvar->on_control_list) {
829 			struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
830 			assert(sender != NULL);
831 
832 			cur_stream->sndvar->on_control_list = TRUE;
833 			TAILQ_INSERT_TAIL(&sender->control_list, cur_stream, sndvar->control_link);
834 			sender->control_list_cnt++;
835 			//TRACE_DBG("Stream %u: added to control list (cnt: %d)\n",
836 			//		cur_stream->id, sender->control_list_cnt);
837 		}
838 #if TRY_SEND_BEFORE_QUEUE
839 	} else {
840 		if (cur_stream->sndvar->on_control_list) {
841 			cur_stream->sndvar->on_control_list = FALSE;
842 			TAILQ_REMOVE(&sender->control_list, cur_stream, sndvar->control_link);
843 			sender->control_list_cnt--;
844 		}
845 	}
846 #endif
847 }
848 /*----------------------------------------------------------------------------*/
849 inline void
850 AddtoSendList(mtcp_manager_t mtcp, tcp_stream *cur_stream)
851 {
852 	struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
853 	assert(sender != NULL);
854 
855 	if(!cur_stream->sndvar->sndbuf) {
856 		TRACE_ERROR("[%d] Stream %d: No send buffer available.\n",
857 				mtcp->ctx->cpu,
858 				cur_stream->id);
859 		assert(0);
860 		return;
861 	}
862 
863 	if (!cur_stream->sndvar->on_send_list) {
864 		cur_stream->sndvar->on_send_list = TRUE;
865 		TAILQ_INSERT_TAIL(&sender->send_list, cur_stream, sndvar->send_link);
866 		sender->send_list_cnt++;
867 	}
868 }
869 /*----------------------------------------------------------------------------*/
870 inline void
871 AddtoACKList(mtcp_manager_t mtcp, tcp_stream *cur_stream)
872 {
873 	struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
874 	assert(sender != NULL);
875 
876 	if (!cur_stream->sndvar->on_ack_list) {
877 		cur_stream->sndvar->on_ack_list = TRUE;
878 		TAILQ_INSERT_TAIL(&sender->ack_list, cur_stream, sndvar->ack_link);
879 		sender->ack_list_cnt++;
880 	}
881 }
882 /*----------------------------------------------------------------------------*/
883 inline void
884 RemoveFromControlList(mtcp_manager_t mtcp, tcp_stream *cur_stream)
885 {
886 	struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
887 	assert(sender != NULL);
888 
889 	if (cur_stream->sndvar->on_control_list) {
890 		cur_stream->sndvar->on_control_list = FALSE;
891 		TAILQ_REMOVE(&sender->control_list, cur_stream, sndvar->control_link);
892 		sender->control_list_cnt--;
893 		//TRACE_DBG("Stream %u: Removed from control list (cnt: %d)\n",
894 		//		cur_stream->id, sender->control_list_cnt);
895 	}
896 }
897 /*----------------------------------------------------------------------------*/
898 inline void
899 RemoveFromSendList(mtcp_manager_t mtcp, tcp_stream *cur_stream)
900 {
901 	struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
902 	assert(sender != NULL);
903 
904 	if (cur_stream->sndvar->on_send_list) {
905 		cur_stream->sndvar->on_send_list = FALSE;
906 		TAILQ_REMOVE(&sender->send_list, cur_stream, sndvar->send_link);
907 		sender->send_list_cnt--;
908 	}
909 }
910 /*----------------------------------------------------------------------------*/
911 inline void
912 RemoveFromACKList(mtcp_manager_t mtcp, tcp_stream *cur_stream)
913 {
914 	struct mtcp_sender *sender = GetSender(mtcp, cur_stream);
915 	assert(sender != NULL);
916 
917 	if (cur_stream->sndvar->on_ack_list) {
918 		cur_stream->sndvar->on_ack_list = FALSE;
919 		TAILQ_REMOVE(&sender->ack_list, cur_stream, sndvar->ack_link);
920 		sender->ack_list_cnt--;
921 	}
922 }
923 /*----------------------------------------------------------------------------*/
924 inline void
925 EnqueueACK(mtcp_manager_t mtcp,
926 		tcp_stream *cur_stream, uint32_t cur_ts, uint8_t opt)
927 {
928 	if (!(cur_stream->state == TCP_ST_ESTABLISHED ||
929 			cur_stream->state == TCP_ST_CLOSE_WAIT ||
930 			cur_stream->state == TCP_ST_FIN_WAIT_1 ||
931 			cur_stream->state == TCP_ST_FIN_WAIT_2)) {
932 		TRACE_DBG("Stream %u: Enqueueing ack at state %s\n",
933 				cur_stream->id, TCPStateToString(cur_stream));
934 	}
935 
936 	if (opt == ACK_OPT_NOW) {
937 		if (cur_stream->sndvar->ack_cnt < cur_stream->sndvar->ack_cnt + 1) {
938 			cur_stream->sndvar->ack_cnt++;
939 		}
940 	} else if (opt == ACK_OPT_AGGREGATE) {
941 		if (cur_stream->sndvar->ack_cnt == 0) {
942 			cur_stream->sndvar->ack_cnt = 1;
943 		}
944 	} else if (opt == ACK_OPT_WACK) {
945 		cur_stream->sndvar->is_wack = TRUE;
946 	}
947 	AddtoACKList(mtcp, cur_stream);
948 }
949 /*----------------------------------------------------------------------------*/
950 inline void
951 DumpControlList(mtcp_manager_t mtcp, struct mtcp_sender *sender)
952 {
953 	tcp_stream *stream;
954 
955 	TRACE_DBG("Dumping control list (count: %d):\n", sender->control_list_cnt);
956 	TAILQ_FOREACH(stream, &sender->control_list, sndvar->control_link) {
957 		TRACE_DBG("Stream id: %u in control list\n", stream->id);
958 	}
959 }
960 /*----------------------------------------------------------------------------*/
961 static inline void
962 UpdatePassiveSendTCPContext_SynSent(struct tcp_stream *cur_stream,
963 				    struct pkt_ctx *pctx)
964 {
965 	assert(cur_stream);
966 	assert(pctx);
967 
968 	/* add event */
969 	if (cur_stream->state < TCP_ST_SYN_SENT) {
970 		cur_stream->cb_events |= MOS_ON_TCP_STATE_CHANGE;
971 		cur_stream->cb_events |= MOS_ON_CONN_START;
972 	}
973 	/* initialize TCP send variables of send-side stream */
974 	cur_stream->sndvar->cwnd = 1;
975 	cur_stream->sndvar->ssthresh = cur_stream->sndvar->mss * 10;
976 	cur_stream->sndvar->ip_id = htons(pctx->p.iph->id);
977 	cur_stream->sndvar->iss = pctx->p.seq;
978 	cur_stream->snd_nxt = pctx->p.seq + 1;
979 	cur_stream->state = TCP_ST_SYN_SENT;
980 	cur_stream->last_active_ts = pctx->p.cur_ts;
981 
982 	/* receive-side conn start event can also be tagged here */
983 	/* blocked since tcp_in.c takes care of this.. */
984 	/* cur_stream->pair_stream->cb_events |= MOS_ON_CONN_START; */
985 }
986 /*----------------------------------------------------------------------------*/
987 /**
988  * Called (when monitoring mode is enabled).. for every incoming packet from the
989  * NIC.
990  */
991 void
992 UpdatePassiveSendTCPContext(mtcp_manager_t mtcp, struct tcp_stream *cur_stream,
993 			    struct pkt_ctx *pctx)
994 {
995 	struct tcphdr *tcph;
996 
997 	assert(cur_stream);
998 	tcph = pctx->p.tcph;
999 
1000 	/* if it is a new TCP stream from client */
1001 	if (tcph->syn && !tcph->ack && cur_stream->state <= TCP_ST_SYN_SENT) {
1002 		TRACE_STATE("Stream %d: %s\n",
1003 			    cur_stream->id, TCPStateToString(cur_stream));
1004 		UpdatePassiveSendTCPContext_SynSent(cur_stream, pctx);
1005 		AddtoTimeoutList(mtcp, cur_stream);
1006 		return;
1007 	}
1008 
1009 	if (tcph->ack) {
1010 		cur_stream->sndvar->ts_lastack_sent = pctx->p.cur_ts;
1011 		cur_stream->last_active_ts = pctx->p.cur_ts;
1012 	}
1013 
1014 	cur_stream->snd_nxt = pctx->p.seq + pctx->p.payloadlen;
1015 
1016 	/* test for reset packet */
1017 	if (tcph->rst) {
1018 		cur_stream->have_reset = TRUE;
1019 		/* test for reset packet */
1020 		cur_stream->state = TCP_ST_CLOSED_RSVD;
1021 		cur_stream->cb_events |= MOS_ON_TCP_STATE_CHANGE;
1022 		TRACE_STATE("Stream %d: %s\n",
1023 				cur_stream->id,
1024 				TCPStateToString(cur_stream));
1025 		return;
1026 	}
1027 
1028 	/*
1029 	 * for all others, state transitioning is based on
1030 	 * current tcp_stream state
1031 	 */
1032 	switch (cur_stream->state) {
1033 	case TCP_ST_SYN_SENT:
1034 		/* control should not come here */
1035 		/* UpdatePassiveReceiveTCPContext() should take care of this */
1036 #ifdef BE_RESILIENT_TO_PACKET_DROP
1037 		if (tcph->ack && TCP_SEQ_GT(pctx->p.seq, cur_stream->sndvar->iss)) {
1038 			cur_stream->state = TCP_ST_ESTABLISHED;
1039 			cur_stream->cb_events |= MOS_ON_TCP_STATE_CHANGE;
1040 			cur_stream->snd_nxt = pctx->p.seq;
1041 			cur_stream->rcv_nxt = pctx->p.ack_seq;
1042 			goto __Handle_TCP_ST_ESTABLISHED;
1043 		}
1044 #endif
1045 		break;
1046 	case TCP_ST_SYN_RCVD:
1047 		if (!tcph->ack)
1048 			break;
1049 
1050 		if (tcph->syn) {
1051 			cur_stream->sndvar->iss = pctx->p.seq;
1052 			cur_stream->snd_nxt = cur_stream->sndvar->iss + 1;
1053 			TRACE_DBG("Stream %d (TCP_ST_SYN_RCVD): "
1054 				  "setting seq: %u = iss\n",
1055 				  cur_stream->id, pctx->p.seq);
1056 		}
1057 #ifdef BE_RESILIENT_TO_PACKET_DROP
1058 		else {
1059 			cur_stream->state = TCP_ST_ESTABLISHED;
1060 			cur_stream->cb_events |= MOS_ON_TCP_STATE_CHANGE;
1061 			cur_stream->snd_nxt = pctx->p.seq;
1062 			cur_stream->rcv_nxt = pctx->p.ack_seq;
1063 			goto __Handle_TCP_ST_ESTABLISHED;
1064 		}
1065 #endif
1066 		TRACE_STATE("Stream %d: %s\n",
1067 			    cur_stream->id,
1068 			    TCPStateToString(cur_stream));
1069 		break;
1070 	case TCP_ST_ESTABLISHED:
1071 #ifdef BE_RESILIENT_TO_PACKET_DROP
1072 __Handle_TCP_ST_ESTABLISHED:
1073 #endif
1074 		/* if application decides to close, fin pkt is sent */
1075 #ifdef BE_RESILIENT_TO_PACKET_DROP
1076 		if (tcph->ack && TCP_SEQ_GT(ntohl(tcph->ack_seq), cur_stream->rcv_nxt))
1077 		{
1078 			RAISE_DEBUG_EVENT(mtcp, cur_stream,
1079 					"Move rcv_nxt from %u to %u.\n",
1080 					cur_stream->rcv_nxt, ntohl(tcph->ack_seq));
1081 			cur_stream->rcv_nxt = ntohl(tcph->ack_seq);
1082 		}
1083 #endif
1084 		if (tcph->fin) {
1085 			cur_stream->state = TCP_ST_FIN_WAIT_1;
1086 			cur_stream->cb_events |= MOS_ON_TCP_STATE_CHANGE;
1087 			cur_stream->sndvar->fss = pctx->p.seq + pctx->p.payloadlen;
1088 			cur_stream->sndvar->is_fin_sent = TRUE;
1089 			cur_stream->snd_nxt++;
1090 			TRACE_STATE("Stream %d: %s\n",
1091 				    cur_stream->id,
1092 				    TCPStateToString(cur_stream));
1093 		} else {
1094 			/* creating tcp send buffer still pending.. */
1095 			/* do we need peek for send buffer? */
1096 		}
1097 		break;
1098 	case TCP_ST_CLOSE_WAIT:
1099 		/* if application decides to close, fin pkt is sent */
1100 #ifdef BE_RESILIENT_TO_PACKET_DROP
1101 		if (tcph->ack && TCP_SEQ_GT(ntohl(tcph->ack_seq), cur_stream->rcv_nxt))
1102 		{
1103 			RAISE_DEBUG_EVENT(mtcp, cur_stream,
1104 					"Move rcv_nxt from %u to %u.\n",
1105 					cur_stream->rcv_nxt, ntohl(tcph->ack_seq));
1106 			cur_stream->rcv_nxt = ntohl(tcph->ack_seq);
1107 		}
1108 #endif
1109 		if (tcph->fin) {
1110 			cur_stream->sndvar->fss = pctx->p.seq + pctx->p.payloadlen;
1111 			cur_stream->sndvar->is_fin_sent = TRUE;
1112 			cur_stream->snd_nxt++;
1113 			cur_stream->state = TCP_ST_LAST_ACK;
1114 			cur_stream->cb_events |= MOS_ON_TCP_STATE_CHANGE;
1115 			TRACE_STATE("Stream %d: %s\n",
1116 				    cur_stream->id,
1117 				    TCPStateToString(cur_stream));
1118 		} else if (tcph->ack) {
1119 			TRACE_STATE("Stream %d: %s\n",
1120 				    cur_stream->id,
1121 				    TCPStateToString(cur_stream));
1122 		}
1123 		break;
1124 	case TCP_ST_LAST_ACK:
1125 		/* control should not come here */
1126 		/* UpdatePassiveReceiveTCPContext() should take care of this */
1127 		break;
1128 	case TCP_ST_FIN_WAIT_1:
1129 		/* control should not come here */
1130 		/* UpdatePassiveReceiveTCPContext() should take care of this */
1131 		break;
1132 	case TCP_ST_FIN_WAIT_2:
1133 		/* control should not come here */
1134 		/* UpdatePassiveReceiveTCPContext() should take care of this */
1135 		break;
1136 	case TCP_ST_CLOSING:
1137 		/* control should not come here */
1138 		/* UpdatePassiveReceiveTCPContext() should take care of this */
1139 		break;
1140 	case TCP_ST_TIME_WAIT:
1141 		/* control may come here but... */
1142 		/* UpdatePassiveReceiveTCPContext() should take care of this */
1143 		if (tcph->ack) {
1144 			TRACE_STATE("Stream %d: %s\n",
1145 				    cur_stream->id,
1146 				    TCPStateToString(cur_stream));
1147 		}
1148 		break;
1149 	case TCP_ST_CLOSED:
1150 	case TCP_ST_CLOSED_RSVD:
1151 		/* Waiting to be destroyed */
1152 		break;
1153 	default:
1154 		TRACE_DBG("This should not happen.. Error state: %s reached!\n"
1155 			  "tcph->syn: %d, tcph->ack: %d\n",
1156 			  TCPStateToString(cur_stream), pctx->p.tcph->syn,
1157 			  pctx->p.tcph->ack);
1158 		assert(0);
1159 		/* This will be enabled once passiverecvcontext is completed */
1160 		/*exit(EXIT_FAILURE);*/
1161 	}
1162 
1163 	UNUSED(mtcp);
1164 	return;
1165 }
1166 /*----------------------------------------------------------------------------*/
1167 void
1168 PostSendTCPAction(mtcp_manager_t mtcp, struct pkt_ctx *pctx,
1169 		  struct tcp_stream *recvside_stream,
1170 		  struct tcp_stream *sendside_stream)
1171 {
1172 	/* this is empty for the time being */
1173 }
1174 /*----------------------------------------------------------------------------*/
1175