1 #include "test_tcp.h"
2 
3 #include "lwip/tcp_impl.h"
4 #include "lwip/stats.h"
5 #include "tcp_helper.h"
6 
7 #ifdef _MSC_VER
8 #pragma warning(disable: 4307) /* we explicitly wrap around TCP seqnos */
9 #endif
10 
11 #if !LWIP_STATS || !TCP_STATS || !MEMP_STATS
12 #error "This tests needs TCP- and MEMP-statistics enabled"
13 #endif
14 #if TCP_SND_BUF <= TCP_WND
15 #error "This tests needs TCP_SND_BUF to be > TCP_WND"
16 #endif
17 
18 static u8_t test_tcp_timer;
19 
20 /* our own version of tcp_tmr so we can reset fast/slow timer state */
21 static void
22 test_tcp_tmr(void)
23 {
24   tcp_fasttmr();
25   if (++test_tcp_timer & 1) {
26     tcp_slowtmr();
27   }
28 }
29 
30 /* Setups/teardown functions */
31 
32 static void
33 tcp_setup(void)
34 {
35   /* reset iss to default (6510) */
36   tcp_ticks = 0;
37   tcp_ticks = 0 - (tcp_next_iss() - 6510);
38   tcp_next_iss();
39   tcp_ticks = 0;
40 
41   test_tcp_timer = 0;
42   tcp_remove_all();
43 }
44 
45 static void
46 tcp_teardown(void)
47 {
48   netif_list = NULL;
49   tcp_remove_all();
50 }
51 
52 
53 /* Test functions */
54 
55 /** Call tcp_new() and tcp_abort() and test memp stats */
56 START_TEST(test_tcp_new_abort)
57 {
58   struct tcp_pcb* pcb;
59   LWIP_UNUSED_ARG(_i);
60 
61   fail_unless(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
62 
63   pcb = tcp_new();
64   fail_unless(pcb != NULL);
65   if (pcb != NULL) {
66     fail_unless(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
67     tcp_abort(pcb);
68     fail_unless(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
69   }
70 }
71 END_TEST
72 
73 /** Create an ESTABLISHED pcb and check if receive callback is called */
74 START_TEST(test_tcp_recv_inseq)
75 {
76   struct test_tcp_counters counters;
77   struct tcp_pcb* pcb;
78   struct pbuf* p;
79   char data[] = {1, 2, 3, 4};
80   ip_addr_t remote_ip, local_ip;
81   u16_t data_len;
82   u16_t remote_port = 0x100, local_port = 0x101;
83   struct netif netif;
84   LWIP_UNUSED_ARG(_i);
85 
86   /* initialize local vars */
87   memset(&netif, 0, sizeof(netif));
88   IP4_ADDR(&local_ip, 192, 168, 1, 1);
89   IP4_ADDR(&remote_ip, 192, 168, 1, 2);
90   data_len = sizeof(data);
91   /* initialize counter struct */
92   memset(&counters, 0, sizeof(counters));
93   counters.expected_data_len = data_len;
94   counters.expected_data = data;
95 
96   /* create and initialize the pcb */
97   pcb = test_tcp_new_counters_pcb(&counters);
98   EXPECT_RET(pcb != NULL);
99   tcp_set_state(pcb, ESTABLISHED, &local_ip, &remote_ip, local_port, remote_port);
100 
101   /* create a segment */
102   p = tcp_create_rx_segment(pcb, counters.expected_data, data_len, 0, 0, 0);
103   EXPECT(p != NULL);
104   if (p != NULL) {
105     /* pass the segment to tcp_input */
106     test_tcp_input(p, &netif);
107     /* check if counters are as expected */
108     EXPECT(counters.close_calls == 0);
109     EXPECT(counters.recv_calls == 1);
110     EXPECT(counters.recved_bytes == data_len);
111     EXPECT(counters.err_calls == 0);
112   }
113 
114   /* make sure the pcb is freed */
115   EXPECT(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
116   tcp_abort(pcb);
117   EXPECT(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
118 }
119 END_TEST
120 
121 /** Provoke fast retransmission by duplicate ACKs and then recover by ACKing all sent data.
122  * At the end, send more data. */
123 START_TEST(test_tcp_fast_retx_recover)
124 {
125   struct netif netif;
126   struct test_tcp_txcounters txcounters;
127   struct test_tcp_counters counters;
128   struct tcp_pcb* pcb;
129   struct pbuf* p;
130   char data1[] = { 1,  2,  3,  4};
131   char data2[] = { 5,  6,  7,  8};
132   char data3[] = { 9, 10, 11, 12};
133   char data4[] = {13, 14, 15, 16};
134   char data5[] = {17, 18, 19, 20};
135   char data6[] = {21, 22, 23, 24};
136   ip_addr_t remote_ip, local_ip, netmask;
137   u16_t remote_port = 0x100, local_port = 0x101;
138   err_t err;
139   LWIP_UNUSED_ARG(_i);
140 
141   /* initialize local vars */
142   IP4_ADDR(&local_ip,  192, 168,   1, 1);
143   IP4_ADDR(&remote_ip, 192, 168,   1, 2);
144   IP4_ADDR(&netmask,   255, 255, 255, 0);
145   test_tcp_init_netif(&netif, &txcounters, &local_ip, &netmask);
146   memset(&counters, 0, sizeof(counters));
147 
148   /* create and initialize the pcb */
149   pcb = test_tcp_new_counters_pcb(&counters);
150   EXPECT_RET(pcb != NULL);
151   tcp_set_state(pcb, ESTABLISHED, &local_ip, &remote_ip, local_port, remote_port);
152   pcb->mss = TCP_MSS;
153   /* disable initial congestion window (we don't send a SYN here...) */
154   pcb->cwnd = pcb->snd_wnd;
155 
156   /* send data1 */
157   err = tcp_write(pcb, data1, sizeof(data1), TCP_WRITE_FLAG_COPY);
158   EXPECT_RET(err == ERR_OK);
159   err = tcp_output(pcb);
160   EXPECT_RET(err == ERR_OK);
161   EXPECT_RET(txcounters.num_tx_calls == 1);
162   EXPECT_RET(txcounters.num_tx_bytes == sizeof(data1) + sizeof(struct tcp_hdr) + sizeof(struct ip_hdr));
163   memset(&txcounters, 0, sizeof(txcounters));
164  /* "recv" ACK for data1 */
165   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 4, TCP_ACK);
166   EXPECT_RET(p != NULL);
167   test_tcp_input(p, &netif);
168   EXPECT_RET(txcounters.num_tx_calls == 0);
169   EXPECT_RET(pcb->unacked == NULL);
170   /* send data2 */
171   err = tcp_write(pcb, data2, sizeof(data2), TCP_WRITE_FLAG_COPY);
172   EXPECT_RET(err == ERR_OK);
173   err = tcp_output(pcb);
174   EXPECT_RET(err == ERR_OK);
175   EXPECT_RET(txcounters.num_tx_calls == 1);
176   EXPECT_RET(txcounters.num_tx_bytes == sizeof(data2) + sizeof(struct tcp_hdr) + sizeof(struct ip_hdr));
177   memset(&txcounters, 0, sizeof(txcounters));
178   /* duplicate ACK for data1 (data2 is lost) */
179   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
180   EXPECT_RET(p != NULL);
181   test_tcp_input(p, &netif);
182   EXPECT_RET(txcounters.num_tx_calls == 0);
183   EXPECT_RET(pcb->dupacks == 1);
184   /* send data3 */
185   err = tcp_write(pcb, data3, sizeof(data3), TCP_WRITE_FLAG_COPY);
186   EXPECT_RET(err == ERR_OK);
187   err = tcp_output(pcb);
188   EXPECT_RET(err == ERR_OK);
189   /* nagle enabled, no tx calls */
190   EXPECT_RET(txcounters.num_tx_calls == 0);
191   EXPECT_RET(txcounters.num_tx_bytes == 0);
192   memset(&txcounters, 0, sizeof(txcounters));
193   /* 2nd duplicate ACK for data1 (data2 and data3 are lost) */
194   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
195   EXPECT_RET(p != NULL);
196   test_tcp_input(p, &netif);
197   EXPECT_RET(txcounters.num_tx_calls == 0);
198   EXPECT_RET(pcb->dupacks == 2);
199   /* queue data4, don't send it (unsent-oversize is != 0) */
200   err = tcp_write(pcb, data4, sizeof(data4), TCP_WRITE_FLAG_COPY);
201   EXPECT_RET(err == ERR_OK);
202   /* 3nd duplicate ACK for data1 (data2 and data3 are lost) -> fast retransmission */
203   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
204   EXPECT_RET(p != NULL);
205   test_tcp_input(p, &netif);
206   /*EXPECT_RET(txcounters.num_tx_calls == 1);*/
207   EXPECT_RET(pcb->dupacks == 3);
208   memset(&txcounters, 0, sizeof(txcounters));
209   /* TODO: check expected data?*/
210 
211   /* send data5, not output yet */
212   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
213   EXPECT_RET(err == ERR_OK);
214   /*err = tcp_output(pcb);
215   EXPECT_RET(err == ERR_OK);*/
216   EXPECT_RET(txcounters.num_tx_calls == 0);
217   EXPECT_RET(txcounters.num_tx_bytes == 0);
218   memset(&txcounters, 0, sizeof(txcounters));
219   {
220     int i = 0;
221     do
222     {
223       err = tcp_write(pcb, data6, TCP_MSS, TCP_WRITE_FLAG_COPY);
224       i++;
225     }while(err == ERR_OK);
226     EXPECT_RET(err != ERR_OK);
227   }
228   err = tcp_output(pcb);
229   EXPECT_RET(err == ERR_OK);
230   /*EXPECT_RET(txcounters.num_tx_calls == 0);
231   EXPECT_RET(txcounters.num_tx_bytes == 0);*/
232   memset(&txcounters, 0, sizeof(txcounters));
233 
234   /* send even more data */
235   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
236   EXPECT_RET(err == ERR_OK);
237   err = tcp_output(pcb);
238   EXPECT_RET(err == ERR_OK);
239   /* ...and even more data */
240   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
241   EXPECT_RET(err == ERR_OK);
242   err = tcp_output(pcb);
243   EXPECT_RET(err == ERR_OK);
244   /* ...and even more data */
245   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
246   EXPECT_RET(err == ERR_OK);
247   err = tcp_output(pcb);
248   EXPECT_RET(err == ERR_OK);
249   /* ...and even more data */
250   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
251   EXPECT_RET(err == ERR_OK);
252   err = tcp_output(pcb);
253   EXPECT_RET(err == ERR_OK);
254 
255   /* send ACKs for data2 and data3 */
256   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 12, TCP_ACK);
257   EXPECT_RET(p != NULL);
258   test_tcp_input(p, &netif);
259   /*EXPECT_RET(txcounters.num_tx_calls == 0);*/
260 
261   /* ...and even more data */
262   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
263   EXPECT_RET(err == ERR_OK);
264   err = tcp_output(pcb);
265   EXPECT_RET(err == ERR_OK);
266   /* ...and even more data */
267   err = tcp_write(pcb, data5, sizeof(data5), TCP_WRITE_FLAG_COPY);
268   EXPECT_RET(err == ERR_OK);
269   err = tcp_output(pcb);
270   EXPECT_RET(err == ERR_OK);
271 
272 #if 0
273   /* create expected segment */
274   p1 = tcp_create_rx_segment(pcb, counters.expected_data, data_len, 0, 0, 0);
275   EXPECT_RET(p != NULL);
276   if (p != NULL) {
277     /* pass the segment to tcp_input */
278     test_tcp_input(p, &netif);
279     /* check if counters are as expected */
280     EXPECT_RET(counters.close_calls == 0);
281     EXPECT_RET(counters.recv_calls == 1);
282     EXPECT_RET(counters.recved_bytes == data_len);
283     EXPECT_RET(counters.err_calls == 0);
284   }
285 #endif
286   /* make sure the pcb is freed */
287   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
288   tcp_abort(pcb);
289   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
290 }
291 END_TEST
292 
293 static u8_t tx_data[TCP_WND*2];
294 
295 static void
296 check_seqnos(struct tcp_seg *segs, int num_expected, u32_t *seqnos_expected)
297 {
298   struct tcp_seg *s = segs;
299   int i;
300   for (i = 0; i < num_expected; i++, s = s->next) {
301     EXPECT_RET(s != NULL);
302     EXPECT(s->tcphdr->seqno == htonl(seqnos_expected[i]));
303   }
304   EXPECT(s == NULL);
305 }
306 
307 /** Send data with sequence numbers that wrap around the u32_t range.
308  * Then, provoke fast retransmission by duplicate ACKs and check that all
309  * segment lists are still properly sorted. */
310 START_TEST(test_tcp_fast_rexmit_wraparound)
311 {
312   struct netif netif;
313   struct test_tcp_txcounters txcounters;
314   struct test_tcp_counters counters;
315   struct tcp_pcb* pcb;
316   struct pbuf* p;
317   ip_addr_t remote_ip, local_ip, netmask;
318   u16_t remote_port = 0x100, local_port = 0x101;
319   err_t err;
320 #define SEQNO1 (0xFFFFFF00 - TCP_MSS)
321 #define ISS    6510
322   u16_t i, sent_total = 0;
323   u32_t seqnos[] = {
324     SEQNO1,
325     SEQNO1 + (1 * TCP_MSS),
326     SEQNO1 + (2 * TCP_MSS),
327     SEQNO1 + (3 * TCP_MSS),
328     SEQNO1 + (4 * TCP_MSS),
329     SEQNO1 + (5 * TCP_MSS)};
330   LWIP_UNUSED_ARG(_i);
331 
332   for (i = 0; i < sizeof(tx_data); i++) {
333     tx_data[i] = (u8_t)i;
334   }
335 
336   /* initialize local vars */
337   IP4_ADDR(&local_ip,  192, 168,   1, 1);
338   IP4_ADDR(&remote_ip, 192, 168,   1, 2);
339   IP4_ADDR(&netmask,   255, 255, 255, 0);
340   test_tcp_init_netif(&netif, &txcounters, &local_ip, &netmask);
341   memset(&counters, 0, sizeof(counters));
342 
343   /* create and initialize the pcb */
344   tcp_ticks = SEQNO1 - ISS;
345   pcb = test_tcp_new_counters_pcb(&counters);
346   EXPECT_RET(pcb != NULL);
347   EXPECT(pcb->lastack == SEQNO1);
348   tcp_set_state(pcb, ESTABLISHED, &local_ip, &remote_ip, local_port, remote_port);
349   pcb->mss = TCP_MSS;
350   /* disable initial congestion window (we don't send a SYN here...) */
351   pcb->cwnd = 2*TCP_MSS;
352 
353   /* send 6 mss-sized segments */
354   for (i = 0; i < 6; i++) {
355     err = tcp_write(pcb, &tx_data[sent_total], TCP_MSS, TCP_WRITE_FLAG_COPY);
356     EXPECT_RET(err == ERR_OK);
357     sent_total += TCP_MSS;
358   }
359   check_seqnos(pcb->unsent, 6, seqnos);
360   EXPECT(pcb->unacked == NULL);
361   err = tcp_output(pcb);
362   EXPECT(txcounters.num_tx_calls == 2);
363   EXPECT(txcounters.num_tx_bytes == 2 * (TCP_MSS + 40U));
364   memset(&txcounters, 0, sizeof(txcounters));
365 
366   check_seqnos(pcb->unacked, 2, seqnos);
367   check_seqnos(pcb->unsent, 4, &seqnos[2]);
368 
369   /* ACK the first segment */
370   p = tcp_create_rx_segment(pcb, NULL, 0, 0, TCP_MSS, TCP_ACK);
371   test_tcp_input(p, &netif);
372   /* ensure this didn't trigger a retransmission */
373   EXPECT(txcounters.num_tx_calls == 1);
374   EXPECT(txcounters.num_tx_bytes == TCP_MSS + 40U);
375   memset(&txcounters, 0, sizeof(txcounters));
376   check_seqnos(pcb->unacked, 2, &seqnos[1]);
377   check_seqnos(pcb->unsent, 3, &seqnos[3]);
378 
379   /* 3 dupacks */
380   EXPECT(pcb->dupacks == 0);
381   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
382   test_tcp_input(p, &netif);
383   EXPECT(txcounters.num_tx_calls == 0);
384   EXPECT(pcb->dupacks == 1);
385   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
386   test_tcp_input(p, &netif);
387   EXPECT(txcounters.num_tx_calls == 0);
388   EXPECT(pcb->dupacks == 2);
389   /* 3rd dupack -> fast rexmit */
390   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
391   test_tcp_input(p, &netif);
392   EXPECT(pcb->dupacks == 3);
393   EXPECT(txcounters.num_tx_calls == 4);
394   memset(&txcounters, 0, sizeof(txcounters));
395   EXPECT(pcb->unsent == NULL);
396   check_seqnos(pcb->unacked, 5, &seqnos[1]);
397 
398   /* make sure the pcb is freed */
399   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
400   tcp_abort(pcb);
401   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
402 }
403 END_TEST
404 
405 /** Send data with sequence numbers that wrap around the u32_t range.
406  * Then, provoke RTO retransmission and check that all
407  * segment lists are still properly sorted. */
408 START_TEST(test_tcp_rto_rexmit_wraparound)
409 {
410   struct netif netif;
411   struct test_tcp_txcounters txcounters;
412   struct test_tcp_counters counters;
413   struct tcp_pcb* pcb;
414   ip_addr_t remote_ip, local_ip, netmask;
415   u16_t remote_port = 0x100, local_port = 0x101;
416   err_t err;
417 #define SEQNO1 (0xFFFFFF00 - TCP_MSS)
418 #define ISS    6510
419   u16_t i, sent_total = 0;
420   u32_t seqnos[] = {
421     SEQNO1,
422     SEQNO1 + (1 * TCP_MSS),
423     SEQNO1 + (2 * TCP_MSS),
424     SEQNO1 + (3 * TCP_MSS),
425     SEQNO1 + (4 * TCP_MSS),
426     SEQNO1 + (5 * TCP_MSS)};
427   LWIP_UNUSED_ARG(_i);
428 
429   for (i = 0; i < sizeof(tx_data); i++) {
430     tx_data[i] = (u8_t)i;
431   }
432 
433   /* initialize local vars */
434   IP4_ADDR(&local_ip,  192, 168,   1, 1);
435   IP4_ADDR(&remote_ip, 192, 168,   1, 2);
436   IP4_ADDR(&netmask,   255, 255, 255, 0);
437   test_tcp_init_netif(&netif, &txcounters, &local_ip, &netmask);
438   memset(&counters, 0, sizeof(counters));
439 
440   /* create and initialize the pcb */
441   tcp_ticks = 0;
442   tcp_ticks = 0 - tcp_next_iss();
443   tcp_ticks = SEQNO1 - tcp_next_iss();
444   pcb = test_tcp_new_counters_pcb(&counters);
445   EXPECT_RET(pcb != NULL);
446   EXPECT(pcb->lastack == SEQNO1);
447   tcp_set_state(pcb, ESTABLISHED, &local_ip, &remote_ip, local_port, remote_port);
448   pcb->mss = TCP_MSS;
449   /* disable initial congestion window (we don't send a SYN here...) */
450   pcb->cwnd = 2*TCP_MSS;
451 
452   /* send 6 mss-sized segments */
453   for (i = 0; i < 6; i++) {
454     err = tcp_write(pcb, &tx_data[sent_total], TCP_MSS, TCP_WRITE_FLAG_COPY);
455     EXPECT_RET(err == ERR_OK);
456     sent_total += TCP_MSS;
457   }
458   check_seqnos(pcb->unsent, 6, seqnos);
459   EXPECT(pcb->unacked == NULL);
460   err = tcp_output(pcb);
461   EXPECT(txcounters.num_tx_calls == 2);
462   EXPECT(txcounters.num_tx_bytes == 2 * (TCP_MSS + 40U));
463   memset(&txcounters, 0, sizeof(txcounters));
464 
465   check_seqnos(pcb->unacked, 2, seqnos);
466   check_seqnos(pcb->unsent, 4, &seqnos[2]);
467 
468   /* call the tcp timer some times */
469   for (i = 0; i < 10; i++) {
470     test_tcp_tmr();
471     EXPECT(txcounters.num_tx_calls == 0);
472   }
473   /* 11th call to tcp_tmr: RTO rexmit fires */
474   test_tcp_tmr();
475   EXPECT(txcounters.num_tx_calls == 1);
476   check_seqnos(pcb->unacked, 1, seqnos);
477   check_seqnos(pcb->unsent, 5, &seqnos[1]);
478 
479   /* fake greater cwnd */
480   pcb->cwnd = pcb->snd_wnd;
481   /* send more data */
482   err = tcp_output(pcb);
483   EXPECT(err == ERR_OK);
484   /* check queues are sorted */
485   EXPECT(pcb->unsent == NULL);
486   check_seqnos(pcb->unacked, 6, seqnos);
487 
488   /* make sure the pcb is freed */
489   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
490   tcp_abort(pcb);
491   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
492 }
493 END_TEST
494 
495 /** Provoke fast retransmission by duplicate ACKs and then recover by ACKing all sent data.
496  * At the end, send more data. */
497 static void test_tcp_tx_full_window_lost(u8_t zero_window_probe_from_unsent)
498 {
499   struct netif netif;
500   struct test_tcp_txcounters txcounters;
501   struct test_tcp_counters counters;
502   struct tcp_pcb* pcb;
503   struct pbuf *p;
504   ip_addr_t remote_ip, local_ip, netmask;
505   u16_t remote_port = 0x100, local_port = 0x101;
506   err_t err;
507   u16_t sent_total, i;
508   u8_t expected = 0xFE;
509 
510   for (i = 0; i < sizeof(tx_data); i++) {
511     u8_t d = (u8_t)i;
512     if (d == 0xFE) {
513       d = 0xF0;
514     }
515     tx_data[i] = d;
516   }
517   if (zero_window_probe_from_unsent) {
518     tx_data[TCP_WND] = expected;
519   } else {
520     tx_data[0] = expected;
521   }
522 
523   /* initialize local vars */
524   IP4_ADDR(&local_ip,  192, 168,   1, 1);
525   IP4_ADDR(&remote_ip, 192, 168,   1, 2);
526   IP4_ADDR(&netmask,   255, 255, 255, 0);
527   test_tcp_init_netif(&netif, &txcounters, &local_ip, &netmask);
528   memset(&counters, 0, sizeof(counters));
529   memset(&txcounters, 0, sizeof(txcounters));
530 
531   /* create and initialize the pcb */
532   pcb = test_tcp_new_counters_pcb(&counters);
533   EXPECT_RET(pcb != NULL);
534   tcp_set_state(pcb, ESTABLISHED, &local_ip, &remote_ip, local_port, remote_port);
535   pcb->mss = TCP_MSS;
536   /* disable initial congestion window (we don't send a SYN here...) */
537   pcb->cwnd = pcb->snd_wnd;
538 
539   /* send a full window (minus 1 packets) of TCP data in MSS-sized chunks */
540   sent_total = 0;
541   if ((TCP_WND - TCP_MSS) % TCP_MSS != 0) {
542     u16_t initial_data_len = (TCP_WND - TCP_MSS) % TCP_MSS;
543     err = tcp_write(pcb, &tx_data[sent_total], initial_data_len, TCP_WRITE_FLAG_COPY);
544     EXPECT_RET(err == ERR_OK);
545     err = tcp_output(pcb);
546     EXPECT_RET(err == ERR_OK);
547     EXPECT(txcounters.num_tx_calls == 1);
548     EXPECT(txcounters.num_tx_bytes == initial_data_len + 40U);
549     memset(&txcounters, 0, sizeof(txcounters));
550     sent_total += initial_data_len;
551   }
552   for (; sent_total < (TCP_WND - TCP_MSS); sent_total += TCP_MSS) {
553     err = tcp_write(pcb, &tx_data[sent_total], TCP_MSS, TCP_WRITE_FLAG_COPY);
554     EXPECT_RET(err == ERR_OK);
555     err = tcp_output(pcb);
556     EXPECT_RET(err == ERR_OK);
557     EXPECT(txcounters.num_tx_calls == 1);
558     EXPECT(txcounters.num_tx_bytes == TCP_MSS + 40U);
559     memset(&txcounters, 0, sizeof(txcounters));
560   }
561   EXPECT(sent_total == (TCP_WND - TCP_MSS));
562 
563   /* now ACK the packet before the first */
564   p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_ACK);
565   test_tcp_input(p, &netif);
566   /* ensure this didn't trigger a retransmission */
567   EXPECT(txcounters.num_tx_calls == 0);
568   EXPECT(txcounters.num_tx_bytes == 0);
569 
570   EXPECT(pcb->persist_backoff == 0);
571   /* send the last packet, now a complete window has been sent */
572   err = tcp_write(pcb, &tx_data[sent_total], TCP_MSS, TCP_WRITE_FLAG_COPY);
573   sent_total += TCP_MSS;
574   EXPECT_RET(err == ERR_OK);
575   err = tcp_output(pcb);
576   EXPECT_RET(err == ERR_OK);
577   EXPECT(txcounters.num_tx_calls == 1);
578   EXPECT(txcounters.num_tx_bytes == TCP_MSS + 40U);
579   memset(&txcounters, 0, sizeof(txcounters));
580   EXPECT(pcb->persist_backoff == 0);
581 
582   if (zero_window_probe_from_unsent) {
583     /* ACK all data but close the TX window */
584     p = tcp_create_rx_segment_wnd(pcb, NULL, 0, 0, TCP_WND, TCP_ACK, 0);
585     test_tcp_input(p, &netif);
586     /* ensure this didn't trigger any transmission */
587     EXPECT(txcounters.num_tx_calls == 0);
588     EXPECT(txcounters.num_tx_bytes == 0);
589     EXPECT(pcb->persist_backoff == 1);
590   }
591 
592   /* send one byte more (out of window) -> persist timer starts */
593   err = tcp_write(pcb, &tx_data[sent_total], 1, TCP_WRITE_FLAG_COPY);
594   EXPECT_RET(err == ERR_OK);
595   err = tcp_output(pcb);
596   EXPECT_RET(err == ERR_OK);
597   EXPECT(txcounters.num_tx_calls == 0);
598   EXPECT(txcounters.num_tx_bytes == 0);
599   memset(&txcounters, 0, sizeof(txcounters));
600   if (!zero_window_probe_from_unsent) {
601     /* no persist timer unless a zero window announcement has been received */
602     EXPECT(pcb->persist_backoff == 0);
603   } else {
604     EXPECT(pcb->persist_backoff == 1);
605 
606     /* call tcp_timer some more times to let persist timer count up */
607     for (i = 0; i < 4; i++) {
608       test_tcp_tmr();
609       EXPECT(txcounters.num_tx_calls == 0);
610       EXPECT(txcounters.num_tx_bytes == 0);
611     }
612 
613     /* this should trigger the zero-window-probe */
614     txcounters.copy_tx_packets = 1;
615     test_tcp_tmr();
616     txcounters.copy_tx_packets = 0;
617     EXPECT(txcounters.num_tx_calls == 1);
618     EXPECT(txcounters.num_tx_bytes == 1 + 40U);
619     EXPECT(txcounters.tx_packets != NULL);
620     if (txcounters.tx_packets != NULL) {
621       u8_t sent;
622       u16_t ret;
623       ret = pbuf_copy_partial(txcounters.tx_packets, &sent, 1, 40U);
624       EXPECT(ret == 1);
625       EXPECT(sent == expected);
626     }
627     if (txcounters.tx_packets != NULL) {
628       pbuf_free(txcounters.tx_packets);
629       txcounters.tx_packets = NULL;
630     }
631   }
632 
633   /* make sure the pcb is freed */
634   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 1);
635   tcp_abort(pcb);
636   EXPECT_RET(lwip_stats.memp[MEMP_TCP_PCB].used == 0);
637 }
638 
639 START_TEST(test_tcp_tx_full_window_lost_from_unsent)
640 {
641   LWIP_UNUSED_ARG(_i);
642   test_tcp_tx_full_window_lost(1);
643 }
644 END_TEST
645 
646 START_TEST(test_tcp_tx_full_window_lost_from_unacked)
647 {
648   LWIP_UNUSED_ARG(_i);
649   test_tcp_tx_full_window_lost(0);
650 }
651 END_TEST
652 
653 /** Create the suite including all tests for this module */
654 Suite *
655 tcp_suite(void)
656 {
657   TFun tests[] = {
658     test_tcp_new_abort,
659     test_tcp_recv_inseq,
660     test_tcp_fast_retx_recover,
661     test_tcp_fast_rexmit_wraparound,
662     test_tcp_rto_rexmit_wraparound,
663     test_tcp_tx_full_window_lost_from_unacked,
664     test_tcp_tx_full_window_lost_from_unsent
665   };
666   return create_suite("TCP", tests, sizeof(tests)/sizeof(TFun), tcp_setup, tcp_teardown);
667 }
668