From 43a3a0c049f0bc5b96c1b86d94653cb4e7882edd Mon Sep 17 00:00:00 2001
From: Chen Yu Dong <chenyudong@espressif.com>
Date: Mon, 26 Apr 2021 16:41:01 +0800
Subject: [PATCH 2/4] ci: Add unit test suite to validate tcp state transitions

---
 test/unit/Filelists.cmake      |   1 +
 test/unit/Filelists.mk         |   1 +
 test/unit/lwip_unittests.c     |   2 +
 test/unit/tcp/tcp_helper.c     |   7 +-
 test/unit/tcp/test_tcp_state.c | 652 +++++++++++++++++++++++++++++++++
 test/unit/tcp/test_tcp_state.h |   8 +
 6 files changed, 670 insertions(+), 1 deletion(-)
 create mode 100644 test/unit/tcp/test_tcp_state.c
 create mode 100644 test/unit/tcp/test_tcp_state.h

diff --git a/test/unit/Filelists.cmake b/test/unit/Filelists.cmake
index 7f5041bd..ba0e5634 100644
--- a/test/unit/Filelists.cmake
+++ b/test/unit/Filelists.cmake
@@ -31,6 +31,7 @@ set(LWIP_TESTFILES
 	${LWIP_TESTDIR}/mqtt/test_mqtt.c
 	${LWIP_TESTDIR}/tcp/tcp_helper.c
 	${LWIP_TESTDIR}/tcp/test_tcp_oos.c
+	${LWIP_TESTDIR}/tcp/test_tcp_state.c
 	${LWIP_TESTDIR}/tcp/test_tcp.c
 	${LWIP_TESTDIR}/udp/test_udp.c
 )
diff --git a/test/unit/Filelists.mk b/test/unit/Filelists.mk
index bb8160a1..52de0db0 100644
--- a/test/unit/Filelists.mk
+++ b/test/unit/Filelists.mk
@@ -47,6 +47,7 @@ TESTFILES=$(TESTDIR)/lwip_unittests.c \
 	$(TESTDIR)/mqtt/test_mqtt.c \
 	$(TESTDIR)/tcp/tcp_helper.c \
 	$(TESTDIR)/tcp/test_tcp_oos.c \
+	$(TESTDIR)/tcp/test_tcp_state.c \
 	$(TESTDIR)/tcp/test_tcp.c \
 	$(TESTDIR)/udp/test_udp.c
 
diff --git a/test/unit/lwip_unittests.c b/test/unit/lwip_unittests.c
index 9fde40e6..b48b3e32 100644
--- a/test/unit/lwip_unittests.c
+++ b/test/unit/lwip_unittests.c
@@ -5,6 +5,7 @@
 #include "udp/test_udp.h"
 #include "tcp/test_tcp.h"
 #include "tcp/test_tcp_oos.h"
+#include "tcp/test_tcp_state.h"
 #include "core/test_def.h"
 #include "core/test_dns.h"
 #include "core/test_mem.h"
@@ -78,6 +79,7 @@ int main(void)
     udp_suite,
     tcp_suite,
     tcp_oos_suite,
+    tcp_state_suite,
     def_suite,
     dns_suite,
     mem_suite,
diff --git a/test/unit/tcp/tcp_helper.c b/test/unit/tcp/tcp_helper.c
index 33ceb20f..61d6e562 100644
--- a/test/unit/tcp/tcp_helper.c
+++ b/test/unit/tcp/tcp_helper.c
@@ -25,7 +25,11 @@ tcp_remove(struct tcp_pcb* pcb_list)
   while(pcb != NULL) {
     pcb2 = pcb;
     pcb = pcb->next;
-    tcp_abort(pcb2);
+    if (pcb2->state == LISTEN) {
+      tcp_close(pcb2);
+    } else {
+      tcp_abort(pcb2);
+    }
   }
 }
 
@@ -260,6 +264,7 @@ void test_tcp_input(struct pbuf *p, struct netif *inp)
   ip_addr_copy_from_ip4(*ip_current_src_addr(), iphdr->src);
   ip_current_netif() = inp;
   ip_data.current_ip4_header = iphdr;
+  ip_data.current_input_netif = inp;
 
   /* since adding IPv6, p->payload must point to tcp header, not ip header */
   pbuf_header(p, -(s16_t)sizeof(struct ip_hdr));
diff --git a/test/unit/tcp/test_tcp_state.c b/test/unit/tcp/test_tcp_state.c
new file mode 100644
index 00000000..6d25eaa5
--- /dev/null
+++ b/test/unit/tcp/test_tcp_state.c
@@ -0,0 +1,652 @@
+#include "test_tcp_state.h"
+
+#include "lwip/priv/tcp_priv.h"
+#include "lwip/stats.h"
+#include "tcp_helper.h"
+#include "lwip/inet_chksum.h"
+
+#ifdef _MSC_VER
+#pragma warning(disable: 4307) /* we explicitly wrap around TCP seqnos */
+#endif
+
+#if !LWIP_STATS || !TCP_STATS || !MEMP_STATS
+#error "This tests needs TCP- and MEMP-statistics enabled"
+#endif
+
+static struct netif test_netif = {0};
+static struct test_tcp_txcounters test_txcounters = {0};
+
+#define SEQNO1 (0xFFFFFF00 - TCP_MSS)
+#define ISS    6510
+static u8_t test_tcp_timer;
+
+/* our own version of tcp_tmr so we can reset fast/slow timer state */
+static void
+test_tcp_tmr(void)
+{
+  tcp_fasttmr();
+  if (++test_tcp_timer & 1) {
+    tcp_slowtmr();
+  }
+}
+
+/* Get TCP flags from packets */
+static u8_t 
+get_tcp_flags_from_packet(struct pbuf *p, u16_t tcp_hdr_offset)
+{
+  struct tcp_hdr tcphdr;
+  u16_t ret;
+  EXPECT_RETX(p != NULL, 0);
+  EXPECT_RETX(p->len >= tcp_hdr_offset + sizeof(struct tcp_hdr), 0);
+  ret = pbuf_copy_partial(p, &tcphdr, sizeof(struct tcp_hdr), tcp_hdr_offset);
+  EXPECT(ret == sizeof(struct tcp_hdr));
+  return TCPH_FLAGS(&tcphdr);
+}
+
+/* Create listening tcp_pcb */
+static struct tcp_pcb_listen *
+create_listening_pcb(u16_t local_port, struct test_tcp_counters *counters)
+{
+  struct tcp_pcb *pcb;
+  struct tcp_pcb_listen *lpcb=NULL;
+  err_t err;
+  u16_t port = local_port?local_port:1234;
+
+  if (counters) {
+    pcb = test_tcp_new_counters_pcb(counters);
+  } else {
+    pcb = tcp_new();
+  }
+  EXPECT(pcb != NULL);
+
+  if (pcb) {
+    err = tcp_bind(pcb, &test_netif.ip_addr, port);
+    EXPECT(err == ERR_OK);
+    lpcb = (struct tcp_pcb_listen *)tcp_listen(pcb);
+  }
+
+  return lpcb;
+}
+
+/* Setups/teardown functions */
+
+static void
+tcp_state_setup(void)
+{
+  struct tcp_pcb dummy_pcb; /* we need this for tcp_next_iss() only */
+
+  /* reset iss to default (6510) */
+  tcp_ticks = 0;
+  tcp_ticks = 0 - (tcp_next_iss(&dummy_pcb) - 6510);
+  tcp_next_iss(&dummy_pcb);
+  tcp_ticks = 0;
+
+  test_tcp_timer = 0;
+  /* initialize local vars */
+  test_tcp_init_netif(&test_netif, &test_txcounters, &test_local_ip, &test_netmask);
+  tcp_remove_all();
+  lwip_check_ensure_no_alloc(SKIP_POOL(MEMP_SYS_TIMEOUT));
+}
+
+static void
+tcp_state_teardown(void)
+{
+  tcp_remove_all();
+  lwip_check_ensure_no_alloc(SKIP_POOL(MEMP_SYS_TIMEOUT));
+}
+
+/* helper functions */
+
+static void 
+test_rst_generation_with_incoming_packet(struct pbuf *p,
+  struct netif *netif, struct test_tcp_txcounters *tx_counters)
+{
+  u16_t tcp_flags;
+  EXPECT_RET(p != NULL);
+  memset(tx_counters, 0, sizeof(struct test_tcp_txcounters));
+  /* pass the segment to tcp_input */
+  tx_counters->copy_tx_packets = 1;
+  test_tcp_input(p, netif);
+  tx_counters->copy_tx_packets = 0;
+  /* check if packets are as expected */
+  EXPECT(tx_counters->tx_packets != NULL);
+  if (tx_counters->tx_packets) {
+    tcp_flags = get_tcp_flags_from_packet(tx_counters->tx_packets, 20);
+    EXPECT(tcp_flags & TCP_RST);
+    pbuf_free(tx_counters->tx_packets);
+    tx_counters->tx_packets = NULL;
+  }
+}
+
+/* Test functions */
+
+/* Call tcp_new() and test memp stats (max number) */
+START_TEST(test_tcp_new_max_num)
+{
+  struct tcp_pcb* pcb[MEMP_NUM_TCP_PCB + 1];
+  int i;
+  LWIP_UNUSED_ARG(_i);
+
+  fail_unless(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+
+  for(i = 0;i < MEMP_NUM_TCP_PCB; i++) {
+    pcb[i] = tcp_new();
+    fail_unless(MEMP_STATS_GET(used, MEMP_TCP_PCB) == (i + 1));
+  }
+  fail_unless(MEMP_STATS_GET(used, MEMP_TCP_PCB) == MEMP_NUM_TCP_PCB);
+  /* Trying to remove the oldest pcb in TIME_WAIT,LAST_ACK,CLOSING state when pcb full */
+  pcb[MEMP_NUM_TCP_PCB] = tcp_new();
+  fail_unless(pcb[MEMP_NUM_TCP_PCB] == NULL);
+  tcp_set_state(pcb[0], TIME_WAIT, &test_local_ip, &test_remote_ip, TEST_LOCAL_PORT, TEST_REMOTE_PORT);
+  pcb[MEMP_NUM_TCP_PCB] = tcp_new();
+  fail_unless(pcb[MEMP_NUM_TCP_PCB] != NULL);
+  fail_unless(MEMP_STATS_GET(used, MEMP_TCP_PCB) == MEMP_NUM_TCP_PCB);
+
+  for (i = 1; i <= MEMP_NUM_TCP_PCB; i++)
+  {
+    tcp_abort(pcb[i]);
+  }
+  fail_unless(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+}
+END_TEST
+
+
+/* pcbs in TIME_WAIT state will be deleted when creating new pcb reach the max number */
+START_TEST(test_tcp_new_max_num_remove_TIME_WAIT)
+{
+  struct tcp_pcb* pcb;
+  struct tcp_pcb* pcb_list[MEMP_NUM_TCP_PCB + 1];
+  int i;
+
+  /* create a pcb in TIME_WAIT state */
+  pcb = tcp_new();
+  EXPECT_RET(pcb != NULL);
+  tcp_set_state(pcb, TIME_WAIT, &test_local_ip, &test_remote_ip, TEST_LOCAL_PORT, TEST_REMOTE_PORT);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  EXPECT_RET(pcb->state == TIME_WAIT);
+
+  /* Create max number pcbs */
+  for(i = 0;i < MEMP_NUM_TCP_PCB-1; i++) {
+    pcb_list[i] = tcp_new();
+    EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == (i + 2));
+  }
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == MEMP_NUM_TCP_PCB);
+
+  /* Create one more pcb, and expect that the pcb in the TIME_WAIT state is deleted */
+  pcb_list[MEMP_NUM_TCP_PCB-1] = tcp_new();
+  EXPECT_RET(pcb_list[MEMP_NUM_TCP_PCB-1] != NULL);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == MEMP_NUM_TCP_PCB);
+
+  for (i = 0; i <= MEMP_NUM_TCP_PCB-1; i++)
+  {
+    tcp_abort(pcb_list[i]);
+  }
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+
+}
+END_TEST
+
+
+/* Call tcp_connect to check active open */
+START_TEST(test_tcp_connect_active_open)
+{
+  struct test_tcp_counters counters;
+  struct tcp_pcb *pcb;
+  struct pbuf *p;
+  err_t err;
+  u16_t test_port = 1234;
+  u32_t seqno = 0;
+
+  /* create and initialize the pcb */
+  tcp_ticks = SEQNO1 - ISS;
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  
+  /* Get seqno from SYN packet */
+  test_txcounters.copy_tx_packets = 1;
+  err = tcp_connect(pcb, &test_remote_ip, test_port, NULL);
+  test_txcounters.copy_tx_packets = 0;
+  EXPECT(err == ERR_OK);
+  EXPECT(pcb->state == SYN_SENT);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+  EXPECT_RET(test_txcounters.tx_packets != NULL);
+  if (test_txcounters.tx_packets != NULL) {
+    struct tcp_hdr tcphdr;
+    u16_t ret;
+    ret = pbuf_copy_partial(test_txcounters.tx_packets, &tcphdr, 20, 20);
+    EXPECT(ret == 20);
+    EXPECT(TCPH_FLAGS(&tcphdr) & TCP_SYN);
+    pbuf_free(test_txcounters.tx_packets);
+    test_txcounters.tx_packets = NULL;
+    seqno = lwip_htonl(tcphdr.seqno);
+    EXPECT(seqno == pcb->lastack);
+  }
+
+  /* check correct syn packet */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, test_port,
+    pcb->local_port, NULL, 0, 12345, seqno + 1, TCP_SYN|TCP_ACK);
+  EXPECT_RET(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT_RET(pcb->state == ESTABLISHED);
+  EXPECT_RET(test_txcounters.num_tx_calls == 2);
+
+  /* make sure the pcb is freed */
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  tcp_abort(pcb);
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+}
+END_TEST
+
+START_TEST(test_tcp_active_close)
+{
+  struct tcp_pcb *pcb, *pcbl;
+  struct test_tcp_counters counters;
+  struct pbuf *p;
+  err_t err;
+  u32_t i;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create TCP in LISTEN state */
+  memset(&counters, 0, sizeof(counters));
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  err = tcp_bind(pcb, &test_netif.ip_addr, 1234);
+  EXPECT_RET(err == ERR_OK);
+  pcbl = tcp_listen(pcb);
+  EXPECT_RET(pcbl != NULL);
+  EXPECT_RET(pcbl->state == LISTEN);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) == 1);
+
+  memset(&test_txcounters, 0, sizeof(test_txcounters));
+  err = tcp_close(pcbl);
+  EXPECT_RET(err == ERR_OK);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) == 0);
+  EXPECT(test_txcounters.num_tx_calls == 0);
+
+  /* close TCP in SYN_SENT state */
+  memset(&counters, 0, sizeof(counters));
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  err = tcp_connect(pcb, &test_netif.gw, 1234, NULL);
+  EXPECT_RET(err == ERR_OK);
+  EXPECT_RET(pcb->state == SYN_SENT);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+
+  memset(&test_txcounters, 0, sizeof(test_txcounters));
+  err = tcp_close(pcb);
+  EXPECT_RET(err == ERR_OK);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+  EXPECT(test_txcounters.num_tx_calls == 0);
+
+  /* close TCP in ESTABLISHED state */
+  memset(&counters, 0, sizeof(counters));
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  tcp_set_state(pcb, ESTABLISHED, &test_local_ip, &test_remote_ip, TEST_LOCAL_PORT, TEST_REMOTE_PORT);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+
+  memset(&test_txcounters, 0, sizeof(test_txcounters));
+  err = tcp_close(pcb);
+  EXPECT_RET(err == ERR_OK);
+  EXPECT_RET(pcb->state == FIN_WAIT_1);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  /* test_tcp_tmr(); */
+  EXPECT(test_txcounters.num_tx_calls == 1);
+  /* create a segment ACK and pass it to tcp_input */
+  p = tcp_create_rx_segment(pcb, NULL, 0, 0, 1, TCP_ACK);
+  EXPECT_RET(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT_RET(pcb->state == FIN_WAIT_2);
+  /* create a segment FIN and pass it to tcp_input */
+  p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_FIN);
+  EXPECT_RET(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT_RET(pcb->state == TIME_WAIT);
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  for (i = 0; i < 2 * TCP_MSL / TCP_TMR_INTERVAL + 1; i++) {
+    test_tcp_tmr();
+  }
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+}
+END_TEST
+
+START_TEST(test_tcp_imultaneous_close)
+{
+  struct test_tcp_counters counters;
+  struct tcp_pcb* pcb;
+  struct pbuf* p;
+  char data = 0x0f;
+  err_t err;
+  u32_t i;
+  LWIP_UNUSED_ARG(_i);
+
+  /* initialize counter struct */
+  memset(&counters, 0, sizeof(counters));
+  counters.expected_data_len = 1;
+  counters.expected_data = &data;
+
+  /* create and initialize the pcb */
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  tcp_set_state(pcb, ESTABLISHED, &test_local_ip, &test_remote_ip, TEST_LOCAL_PORT, TEST_REMOTE_PORT);
+  err = tcp_close(pcb);
+  EXPECT_RET(err == ERR_OK);
+  EXPECT_RET(pcb->state == FIN_WAIT_1);
+  /* create a FIN segment */
+  p = tcp_create_rx_segment(pcb, &data, 0, 0, 0, TCP_FIN);
+  EXPECT(p != NULL);
+  if (p != NULL) {
+    test_tcp_input(p, &test_netif);
+  }
+  EXPECT_RET(pcb->state == CLOSING);
+  /* create an ACK segment */
+  p = tcp_create_rx_segment(pcb, &data, 0, 0, 1, TCP_ACK);
+  EXPECT(p != NULL);
+  if (p != NULL) {
+    test_tcp_input(p, &test_netif);
+  }
+  EXPECT_RET(pcb->state == TIME_WAIT);
+  for (i = 0; i < 2 * TCP_MSL / TCP_TMR_INTERVAL + 1; i++) {
+    test_tcp_tmr();
+  }
+  EXPECT_RET(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+}
+END_TEST
+
+
+/* RST was generated when receive any incoming segment in CLOSED state */
+START_TEST(test_tcp_gen_rst_in_CLOSED)
+{
+  struct pbuf *p;
+  ip_addr_t src_addr = test_remote_ip;
+  ip_addr_t dst_addr = test_local_ip;
+  LWIP_UNUSED_ARG(_i);
+
+  /* Do not create any pcb */
+
+  /* create a segment */
+  p = tcp_create_segment(&src_addr, &dst_addr, TEST_REMOTE_PORT,
+    TEST_LOCAL_PORT, NULL, 0, 12345, 54321, TCP_ACK);
+  EXPECT(p != NULL);
+  test_rst_generation_with_incoming_packet(p, &test_netif, &test_txcounters);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+
+}
+END_TEST
+
+/* RST was generated when receive ACK in LISTEN state */
+START_TEST(test_tcp_gen_rst_in_LISTEN)
+{
+  struct tcp_pcb_listen *lpcb;
+  struct pbuf *p;
+  ip_addr_t src_addr = test_remote_ip;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create a pcb in LISTEN state */
+  lpcb = create_listening_pcb(TEST_LOCAL_PORT, NULL);
+  EXPECT_RET(lpcb != NULL);
+
+  /* create a segment */
+  p = tcp_create_segment(&src_addr,&lpcb->local_ip, TEST_REMOTE_PORT,
+    lpcb->local_port, NULL, 0, 12345, 54321, TCP_ACK);
+  EXPECT(p != NULL);
+  test_rst_generation_with_incoming_packet(p, &test_netif, &test_txcounters);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+
+  /* the PCB still in LISTEN state */
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) == 1);
+  if (MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) != 0) {
+    /* can not use tcp_abort() */
+    tcp_close((struct tcp_pcb *)lpcb);
+  }
+
+}
+END_TEST
+
+
+/* RST was generated when receive an SYN in TIME_WAIT state */
+START_TEST(test_tcp_gen_rst_in_TIME_WAIT)
+{
+  struct tcp_pcb *pcb;
+  struct pbuf *p;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create a pcb in LISTEN state */
+  pcb = tcp_new();
+  EXPECT_RET(pcb != NULL);
+  tcp_set_state(pcb, TIME_WAIT, &test_local_ip, &test_remote_ip, TEST_LOCAL_PORT, TEST_REMOTE_PORT);
+
+  /* create a segment */
+  p = tcp_create_rx_segment(pcb, NULL, 0, 0, 0, TCP_SYN);
+  EXPECT(p != NULL);
+  test_rst_generation_with_incoming_packet(p, &test_netif, &test_txcounters);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  EXPECT(pcb->state == TIME_WAIT);
+}
+END_TEST
+
+/* receive TCP_RST with different seqno */
+START_TEST(test_tcp_process_rst_seqno)
+{
+  struct test_tcp_counters counters;
+  struct tcp_pcb *pcb;
+  struct pbuf *p;
+  err_t err;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create and initialize a pcb in SYN_SENT state */
+  memset(&counters, 0, sizeof(counters));
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  err = tcp_connect(pcb, &test_remote_ip, TEST_REMOTE_PORT, NULL);
+  EXPECT_RET(err == ERR_OK);
+
+  /* a RST segment with incorrect seqno will not be accepted */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, TEST_REMOTE_PORT,
+    pcb->local_port, NULL, 0, 12345,  pcb->snd_nxt-10, TCP_RST);
+  EXPECT(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT(counters.err_calls == 0);
+
+  /* a RST segment with correct seqno will be accepted */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, TEST_REMOTE_PORT,
+    pcb->local_port, NULL, 0, 12345,  pcb->snd_nxt, TCP_RST);
+  EXPECT(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT(counters.err_calls == 1);
+  counters.err_calls = 0;
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+
+  /* create another pcb in ESTABLISHED state */
+  memset(&counters, 0, sizeof(counters));
+  pcb = test_tcp_new_counters_pcb(&counters);
+  EXPECT_RET(pcb != NULL);
+  tcp_set_state(pcb, ESTABLISHED, &test_local_ip, &test_remote_ip, TEST_LOCAL_PORT, TEST_REMOTE_PORT);
+
+  /* a RST segment with incorrect seqno will not be accepted */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, pcb->remote_port,
+    pcb->local_port, NULL, 0, pcb->rcv_nxt-10, 54321, TCP_RST);
+  EXPECT(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT(counters.err_calls == 0);
+
+  /* a RST segment with correct seqno will be accepted */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, TEST_REMOTE_PORT,
+    pcb->local_port, NULL, 0, pcb->rcv_nxt, 54321, TCP_RST);
+  EXPECT(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT(counters.err_calls == 1);
+  counters.err_calls = 0;
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+
+}
+END_TEST
+
+/* RST was generated when receive an SYN+ACK with incorrect ACK number in SYN_SENT state */
+START_TEST(test_tcp_gen_rst_in_SYN_SENT_ackseq)
+{
+  struct tcp_pcb *pcb;
+  struct pbuf *p;
+  u16_t test_port = 1234;
+  err_t err;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create and initialize a pcb in listen state */
+  pcb = tcp_new();
+  EXPECT_RET(pcb != NULL);
+  err = tcp_connect(pcb, &test_remote_ip, test_port, NULL);
+  EXPECT_RET(err == ERR_OK);
+
+  /* create a SYN+ACK segment with incorrect seqno */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, pcb->remote_port,
+    pcb->local_port, NULL, 0, 12345,  pcb->lastack-10, TCP_SYN|TCP_ACK);
+  EXPECT(p != NULL);
+  test_rst_generation_with_incoming_packet(p, &test_netif, &test_txcounters);
+
+  /* LWIP: send RST then re-send SYN immediately */
+  EXPECT(test_txcounters.num_tx_calls == 2);
+
+}
+END_TEST
+
+/* RST was generated when receive an ACK without SYN in SYN_SENT state */
+START_TEST(test_tcp_gen_rst_in_SYN_SENT_non_syn_ack)
+{
+  struct tcp_pcb *pcb;
+  struct pbuf *p;
+  u16_t test_port = 1234;
+  err_t err;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create and initialize a pcb in listen state */
+  pcb = tcp_new();
+  EXPECT_RET(pcb != NULL);
+  err = tcp_connect(pcb, &test_remote_ip, test_port, NULL);
+  EXPECT_RET(err == ERR_OK);
+
+  /* create a SYN+ACK segment with incorrect seqno */
+  p = tcp_create_segment(&pcb->remote_ip, &pcb->local_ip, pcb->remote_port,
+    pcb->local_port, NULL, 0, 12345,  pcb->lastack, TCP_ACK);
+  EXPECT(p != NULL);
+  test_rst_generation_with_incoming_packet(p, &test_netif, &test_txcounters);
+
+  /* LWIP: send RST then re-send SYN immediately */
+  EXPECT(test_txcounters.num_tx_calls == 2);
+
+}
+END_TEST
+
+/* RST was generated when receive an ACK with incorrect seqno in SYN_RCVD state */
+START_TEST(test_tcp_gen_rst_in_SYN_RCVD)
+{
+  struct tcp_pcb_listen *lpcb;
+  struct pbuf *p;
+  u32_t ack_seqno = 0;
+  ip_addr_t src_addr = test_remote_ip;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create and initialize a pcb in listen state */
+  lpcb = create_listening_pcb(TEST_LOCAL_PORT, NULL);
+  EXPECT_RET(lpcb != NULL);
+
+  /* LISTEN -> SYN_RCVD */
+  p = tcp_create_segment(&src_addr, &lpcb->local_ip, TEST_REMOTE_PORT,
+    lpcb->local_port, NULL, 0, 1000, 54321, TCP_SYN);
+  EXPECT(p != NULL);
+  memset(&test_txcounters, 0, sizeof(struct test_tcp_txcounters));
+  test_tcp_input(p, &test_netif);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  if (MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1) {
+    ack_seqno = tcp_active_pcbs[0].lastack;
+  }
+
+  /* create a ACK segment with incorrect seqno */
+  p = tcp_create_segment(&src_addr, &lpcb->local_ip, TEST_REMOTE_PORT,
+    lpcb->local_port, NULL, 0, 1001, ack_seqno+1111, TCP_ACK);
+  EXPECT(p != NULL);
+  test_rst_generation_with_incoming_packet(p, &test_netif, &test_txcounters);
+  EXPECT(test_txcounters.num_tx_calls == 1);
+
+  /* the active pcb still exists */
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) == 1);
+  if (MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) != 0) {
+    /* can not use tcp_abort() */
+    tcp_close((struct tcp_pcb *)lpcb);
+  }
+}
+END_TEST
+
+/* a listen pcb returns to LISTEN from SYN_RCVD when RST received */
+START_TEST(test_tcp_receive_rst_SYN_RCVD_to_LISTEN)
+{
+  struct tcp_pcb_listen *lpcb;
+  struct pbuf *p;
+  u16_t tcp_flags;
+  ip_addr_t src_addr = test_remote_ip;
+  LWIP_UNUSED_ARG(_i);
+
+  /* create and initialize a pcb in listen state */
+  lpcb = create_listening_pcb(TEST_LOCAL_PORT, NULL);
+  EXPECT_RET(lpcb != NULL);
+
+  /* create a SYN segment */
+  p = tcp_create_segment(&src_addr, &lpcb->local_ip, TEST_REMOTE_PORT,
+    lpcb->local_port, NULL, 0, 1000, 54321, TCP_SYN);
+  EXPECT(p != NULL);
+  /* pass the segment to tcp_input */
+  memset(&test_txcounters, 0, sizeof(struct test_tcp_txcounters));
+  test_txcounters.copy_tx_packets = 1;
+  test_tcp_input(p, &test_netif);
+  test_txcounters.copy_tx_packets = 0;
+  /* check if packets are as expected */
+  EXPECT(test_txcounters.num_tx_calls == 1);
+  tcp_flags = get_tcp_flags_from_packet(test_txcounters.tx_packets, 20);
+  pbuf_free(test_txcounters.tx_packets);
+  test_txcounters.tx_packets = NULL;
+  EXPECT((tcp_flags & TCP_SYN) && (tcp_flags & TCP_ACK));
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 1);
+
+  /* create a RST segment */
+  p = tcp_create_segment(&src_addr, &lpcb->local_ip, TEST_REMOTE_PORT,
+    lpcb->local_port, NULL, 0, 1001, 54321, TCP_RST);
+  EXPECT(p != NULL);
+  test_tcp_input(p, &test_netif);
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB) == 0);
+  EXPECT(MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) == 1);
+
+  if (MEMP_STATS_GET(used, MEMP_TCP_PCB_LISTEN) != 0) {
+    /* can not use tcp_abort() */
+    tcp_close((struct tcp_pcb *)lpcb);
+  }
+}
+END_TEST
+
+/** Create the suite including all tests for this module */
+Suite *
+tcp_state_suite(void)
+{
+  testfunc tests[] = {
+    TESTFUNC(test_tcp_new_max_num),
+    TESTFUNC(test_tcp_new_max_num_remove_TIME_WAIT),
+    TESTFUNC(test_tcp_connect_active_open),
+    TESTFUNC(test_tcp_active_close),
+    TESTFUNC(test_tcp_imultaneous_close),
+    TESTFUNC(test_tcp_gen_rst_in_CLOSED),
+    TESTFUNC(test_tcp_gen_rst_in_LISTEN),
+    TESTFUNC(test_tcp_gen_rst_in_TIME_WAIT),
+    TESTFUNC(test_tcp_process_rst_seqno),
+    TESTFUNC(test_tcp_gen_rst_in_SYN_SENT_ackseq),
+    TESTFUNC(test_tcp_gen_rst_in_SYN_SENT_non_syn_ack),
+    TESTFUNC(test_tcp_gen_rst_in_SYN_RCVD),
+    TESTFUNC(test_tcp_receive_rst_SYN_RCVD_to_LISTEN),
+  };
+  return create_suite("TCP_STATE", tests, sizeof(tests) / sizeof(testfunc), tcp_state_setup, tcp_state_teardown);
+}
diff --git a/test/unit/tcp/test_tcp_state.h b/test/unit/tcp/test_tcp_state.h
new file mode 100644
index 00000000..00d5c8a4
--- /dev/null
+++ b/test/unit/tcp/test_tcp_state.h
@@ -0,0 +1,8 @@
+#ifndef LWIP_HDR_TEST_TCP_STATE_H
+#define LWIP_HDR_TEST_TCP_STATE_H
+
+#include "../lwip_check.h"
+
+Suite *tcp_state_suite(void);
+
+#endif
-- 
2.25.1

