fix bug #53971 Lwip sends Router Solicitation on address changes

... and add a unit test for it.

Moved resetting netif->rs_count from all reports to link-up and netif-up only.
While at it, clean up the interface a bit so that netif->rs_count is touched
from nd6.c only.

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>

src/core/ipv6/nd6.c

@@ -2405,4 +2405,14 @@ nd6_adjust_mld_membership(struct netif *netif, s8_t addr_idx, u8_t new_state)
 }
 #endif /* LWIP_IPV6_MLD */
 
+/** Netif was added, set up, or reconnected (link up) */
+void
+nd6_restart_netif(struct netif *netif)
+{
+#if LWIP_IPV6_SEND_ROUTER_SOLICIT
+  /* Send Router Solicitation messages (see RFC 4861, ch. 6.3.7). */
+  netif->rs_count = LWIP_ND6_MAX_MULTICAST_SOLICIT;
+#endif /* LWIP_IPV6_SEND_ROUTER_SOLICIT */
+}
+
 #endif /* LWIP_IPV6 */

src/core/netif.c

@@ -322,13 +322,13 @@ netif_add(struct netif *netif,
 #ifdef netif_get_client_data
   memset(netif->client_data, 0, sizeof(netif->client_data));
 #endif /* LWIP_NUM_NETIF_CLIENT_DATA */
+#if LWIP_IPV6
 #if LWIP_IPV6_AUTOCONFIG
   /* IPv6 address autoconfiguration not enabled by default */
   netif->ip6_autoconfig_enabled = 0;
 #endif /* LWIP_IPV6_AUTOCONFIG */
-#if LWIP_IPV6_SEND_ROUTER_SOLICIT
-  netif->rs_count = LWIP_ND6_MAX_MULTICAST_SOLICIT;
-#endif /* LWIP_IPV6_SEND_ROUTER_SOLICIT */
+  nd6_restart_netif(netif);
+#endif /* LWIP_IPV6 */
 #if LWIP_NETIF_STATUS_CALLBACK
   netif->status_callback = NULL;
 #endif /* LWIP_NETIF_STATUS_CALLBACK */
@@ -842,6 +842,9 @@ netif_set_up(struct netif *netif)
 #endif
 
     netif_issue_reports(netif, NETIF_REPORT_TYPE_IPV4 | NETIF_REPORT_TYPE_IPV6);
+#if LWIP_IPV6
+    nd6_restart_netif(netif);
+#endif /* LWIP_IPV6 */
   }
 }
 
@@ -881,10 +884,6 @@ netif_issue_reports(struct netif *netif, u8_t report_type)
     /* send mld memberships */
     mld6_report_groups(netif);
 #endif /* LWIP_IPV6_MLD */
-#if LWIP_IPV6_SEND_ROUTER_SOLICIT
-    /* Send Router Solicitation messages. */
-    netif->rs_count = LWIP_ND6_MAX_MULTICAST_SOLICIT;
-#endif /* LWIP_IPV6_SEND_ROUTER_SOLICIT */
   }
 #endif /* LWIP_IPV6 */
 }
@@ -977,6 +976,9 @@ netif_set_link_up(struct netif *netif)
 #endif /* LWIP_AUTOIP */
 
     netif_issue_reports(netif, NETIF_REPORT_TYPE_IPV4 | NETIF_REPORT_TYPE_IPV6);
+#if LWIP_IPV6
+    nd6_restart_netif(netif);
+#endif /* LWIP_IPV6 */
 
     NETIF_LINK_CALLBACK(netif);
 #if LWIP_NETIF_EXT_STATUS_CALLBACK

src/include/lwip/nd6.h

@@ -74,6 +74,7 @@ void nd6_cleanup_netif(struct netif *netif);
 #if LWIP_IPV6_MLD
 void nd6_adjust_mld_membership(struct netif *netif, s8_t addr_idx, u8_t new_state);
 #endif /* LWIP_IPV6_MLD */
+void nd6_restart_netif(struct netif *netif);
 
 #ifdef __cplusplus
 }

test/unit/ip6/test_ip6.c

@@ -0,0 +1,172 @@
+#include "test_ip6.h"
+
+#include "lwip/ethip6.h"
+#include "lwip/ip6.h"
+#include "lwip/inet_chksum.h"
+#include "lwip/nd6.h"
+#include "lwip/stats.h"
+#include "lwip/prot/ethernet.h"
+#include "lwip/prot/ip.h"
+#include "lwip/prot/ip6.h"
+
+#include "lwip/tcpip.h"
+
+#if LWIP_IPV6 /* allow to build the unit tests without IPv6 support */
+
+static struct netif test_netif6;
+static int linkoutput_ctr;
+
+static err_t
+default_netif_linkoutput(struct netif *netif, struct pbuf *p)
+{
+  fail_unless(netif == &test_netif6);
+  fail_unless(p != NULL);
+  linkoutput_ctr++;
+  return ERR_OK;
+}
+
+static err_t
+default_netif_init(struct netif *netif)
+{
+  fail_unless(netif != NULL);
+  netif->linkoutput = default_netif_linkoutput;
+  netif->output_ip6 = ethip6_output;
+  netif->mtu = 1500;
+  netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHERNET | NETIF_FLAG_MLD6;
+  netif->hwaddr_len = ETH_HWADDR_LEN;
+  return ERR_OK;
+}
+
+static void
+default_netif_add(void)
+{
+  struct netif *n;
+  fail_unless(netif_default == NULL);
+  n = netif_add_noaddr(&test_netif6, NULL, default_netif_init, NULL);
+  fail_unless(n == &test_netif6);
+  netif_set_default(&test_netif6);
+}
+
+static void
+default_netif_remove(void)
+{
+  fail_unless(netif_default == &test_netif6);
+  netif_remove(&test_netif6);
+}
+
+static void
+ip6_test_handle_timers(int count)
+{
+  int i;
+  for (i = 0; i < count; i++) {
+    nd6_tmr();
+  }
+}
+
+/* Setups/teardown functions */
+
+static void
+ip6_setup(void)
+{
+  default_netif_add();
+  lwip_check_ensure_no_alloc(SKIP_POOL(MEMP_SYS_TIMEOUT));
+}
+
+static void
+ip6_teardown(void)
+{
+  if (netif_list->loop_first != NULL) {
+    pbuf_free(netif_list->loop_first);
+    netif_list->loop_first = NULL;
+  }
+  netif_list->loop_last = NULL;
+  /* poll until all memory is released... */
+  tcpip_thread_poll_one();
+  default_netif_remove();
+  lwip_check_ensure_no_alloc(SKIP_POOL(MEMP_SYS_TIMEOUT));
+}
+
+
+/* Test functions */
+
+static void
+test_ip6_ll_addr_iter(int expected_ctr1, int expected_ctr2)
+{
+  fail_unless(linkoutput_ctr == 0);
+
+  /* test that nothing is sent with link uo but netif down */
+  netif_set_link_up(&test_netif6);
+  ip6_test_handle_timers(500);
+  fail_unless(linkoutput_ctr == 0);
+  netif_set_link_down(&test_netif6);
+  fail_unless(linkoutput_ctr == 0);
+
+  /* test that nothing is sent with link down but netif up */
+  netif_set_up(&test_netif6);
+  ip6_test_handle_timers(500);
+  fail_unless(linkoutput_ctr == 0);
+  netif_set_down(&test_netif6);
+  fail_unless(linkoutput_ctr == 0);
+
+  /* test what is sent with link up + netif up */
+  netif_set_link_up(&test_netif6);
+  netif_set_up(&test_netif6);
+  ip6_test_handle_timers(500);
+  fail_unless(linkoutput_ctr == expected_ctr1);
+  netif_set_down(&test_netif6);
+  netif_set_link_down(&test_netif6);
+  fail_unless(linkoutput_ctr == expected_ctr1);
+  linkoutput_ctr = 0;
+
+  netif_set_up(&test_netif6);
+  netif_set_link_up(&test_netif6);
+  ip6_test_handle_timers(500);
+  fail_unless(linkoutput_ctr == expected_ctr2);
+  netif_set_link_down(&test_netif6);
+  netif_set_down(&test_netif6);
+  fail_unless(linkoutput_ctr == expected_ctr2);
+  linkoutput_ctr = 0;
+}
+
+START_TEST(test_ip6_ll_addr)
+{
+  LWIP_UNUSED_ARG(_i);
+
+  /* test without link-local address */
+  test_ip6_ll_addr_iter(0, 0);
+
+  /* test with link-local address */
+  netif_create_ip6_linklocal_address(&test_netif6, 1);
+  test_ip6_ll_addr_iter(3 + LWIP_IPV6_DUP_DETECT_ATTEMPTS + LWIP_IPV6_MLD, 3);
+}
+END_TEST
+
+
+/** Create the suite including all tests for this module */
+Suite *
+ip6_suite(void)
+{
+  testfunc tests[] = {
+    TESTFUNC(test_ip6_ll_addr),
+  };
+  return create_suite("IPv6", tests, sizeof(tests)/sizeof(testfunc), ip6_setup, ip6_teardown);
+}
+
+#else /* LWIP_IPV6 */
+
+/* allow to build the unit tests without IPv6 support */
+START_TEST(test_ip6_dummy)
+{
+  LWIP_UNUSED_ARG(_i);
+}
+END_TEST
+
+Suite *
+ip6_suite(void)
+{
+  testfunc tests[] = {
+    TESTFUNC(test_ip6_dummy),
+  };
+  return create_suite("IPv6", tests, sizeof(tests)/sizeof(testfunc), NULL, NULL);
+}
+#endif /* LWIP_IPV6 */

test/unit/ip6/test_ip6.h

@@ -0,0 +1,8 @@
+#ifndef LWIP_HDR_TEST_IP6_H
+#define LWIP_HDR_TEST_IP6_H
+
+#include "../lwip_check.h"
+
+Suite* ip6_suite(void);
+
+#endif

test/unit/lwip_unittests.c

@@ -1,6 +1,7 @@
 #include "lwip_check.h"
 
 #include "ip4/test_ip4.h"
+#include "ip6/test_ip6.h"
 #include "udp/test_udp.h"
 #include "tcp/test_tcp.h"
 #include "tcp/test_tcp_oos.h"
@@ -62,6 +63,7 @@ int main(void)
   size_t i;
   suite_getter_fn* suites[] = {
     ip4_suite,
+    ip6_suite,
     udp_suite,
     tcp_suite,
     tcp_oos_suite,