fix gw ARP on startup

mongoose.c

@@ -5127,6 +5127,8 @@ static void onstatechange(struct mg_tcpip_if *ifp) {
     MG_INFO(("READY, IP: %M", mg_print_ip4, &ifp->ip));
     MG_INFO(("       GW: %M", mg_print_ip4, &ifp->gw));
     MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
+  } else if (ifp->state == MG_TCPIP_STATE_IP) {
+    MG_ERROR(("Got IP"));
     mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // unsolicited GW ARP request
   } else if (ifp->state == MG_TCPIP_STATE_UP) {
     MG_ERROR(("Link up"));
@@ -5277,8 +5279,12 @@ static void rx_arp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
   } else if (pkt->arp->op == mg_htons(2)) {
     if (memcmp(pkt->arp->tha, ifp->mac, sizeof(pkt->arp->tha)) != 0) return;
     if (pkt->arp->spa == ifp->gw) {
-      // Got response for the GW ARP request. Set ifp->gwmac
+      // Got response for the GW ARP request. Set ifp->gwmac and IP -> READY
       memcpy(ifp->gwmac, pkt->arp->sha, sizeof(ifp->gwmac));
+      if (ifp->state == MG_TCPIP_STATE_IP) {
+        ifp->state = MG_TCPIP_STATE_READY;
+        onstatechange(ifp);
+      }
     } else {
       struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
       if (c != NULL && c->is_arplooking) {
@@ -5353,7 +5359,7 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
       // assume DHCP server = router until ARP resolves
       memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
       ifp->ip = ip, ifp->gw = gw, ifp->mask = mask;
-      ifp->state = MG_TCPIP_STATE_READY;  // BOUND state
+      ifp->state = MG_TCPIP_STATE_IP;  // BOUND state
       uint64_t rand;
       mg_random(&rand, sizeof(rand));
       srand((unsigned int) (rand + mg_millis()));
@@ -5401,7 +5407,7 @@ static void rx_dhcp_server(struct mg_tcpip_if *ifp, struct pkt *pkt) {
     res.magic = pkt->dhcp->magic;
     res.xid = pkt->dhcp->xid;
     if (ifp->enable_get_gateway) {
-      ifp->gw = res.yiaddr;
+      ifp->gw = res.yiaddr;  // set gw IP, best-effort gwmac as DHCP server's
       memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
     }
     tx_udp(ifp, pkt->eth->src, ifp->ip, mg_htons(67),
@@ -5818,12 +5824,17 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
 
 #if MG_ENABLE_TCPIP_PRINT_DEBUG_STATS
   if (expired_1000ms) {
-    const char *names[] = {"down", "up", "req", "ready"};
+    const char *names[] = {"down", "up", "req", "ip", "ready"};
     MG_INFO(("Status: %s, IP: %M, rx:%u, tx:%u, dr:%u, er:%u",
              names[ifp->state], mg_print_ip4, &ifp->ip, ifp->nrecv, ifp->nsent,
              ifp->ndrop, ifp->nerr));
   }
 #endif
+  // Handle gw ARP request timeout, order is important
+  if (expired_1000ms && ifp->state == MG_TCPIP_STATE_IP) {
+    ifp->state = MG_TCPIP_STATE_READY; // keep best-effort MAC
+    onstatechange(ifp);
+  }
   // Handle physical interface up/down status
   if (expired_1000ms && ifp->driver->up) {
     bool up = ifp->driver->up(ifp);
@@ -5833,11 +5844,11 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
       ifp->state = up == false ? MG_TCPIP_STATE_DOWN
                    : ifp->enable_dhcp_client || ifp->ip == 0
                        ? MG_TCPIP_STATE_UP
-                       : MG_TCPIP_STATE_READY;
+                       : MG_TCPIP_STATE_IP;
       onstatechange(ifp);
     } else if (!ifp->enable_dhcp_client && ifp->state == MG_TCPIP_STATE_UP &&
                ifp->ip) {
-      ifp->state = MG_TCPIP_STATE_READY;  // ifp->fn has set an IP
+      ifp->state = MG_TCPIP_STATE_IP;  // ifp->fn has set an IP
       onstatechange(ifp);
     }
     if (ifp->state == MG_TCPIP_STATE_DOWN) MG_ERROR(("Network is down"));
@@ -5953,7 +5964,7 @@ void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
     ifp->mtu = MG_TCPIP_MTU_DEFAULT;
     mgr->extraconnsize = sizeof(struct connstate);
     if (ifp->ip == 0) ifp->enable_dhcp_client = true;
-    memset(ifp->gwmac, 255, sizeof(ifp->gwmac));  // Set to broadcast
+    memset(ifp->gwmac, 255, sizeof(ifp->gwmac));  // Set best-effort to bcast
     mg_random(&ifp->eport, sizeof(ifp->eport));   // Random from 0 to 65535
     ifp->eport |= MG_EPHEMERAL_PORT_BASE;         // Random from
                                            // MG_EPHEMERAL_PORT_BASE to 65535

mongoose.h

@@ -2777,8 +2777,9 @@ struct mg_tcpip_if {
   uint8_t state;                // Current state
 #define MG_TCPIP_STATE_DOWN 0   // Interface is down
 #define MG_TCPIP_STATE_UP 1     // Interface is up
-#define MG_TCPIP_STATE_REQ 2    // Interface is up and has requested an IP
+#define MG_TCPIP_STATE_REQ 2    // Interface is up, DHCP REQUESTING state
-#define MG_TCPIP_STATE_READY 3  // Interface is up and has an IP assigned
+#define MG_TCPIP_STATE_IP 3     // Interface is up and has an IP assigned
+#define MG_TCPIP_STATE_READY 4  // Interface has fully come up, ready to work
 };
 
 void mg_tcpip_init(struct mg_mgr *, struct mg_tcpip_if *);

src/net_builtin.c

@@ -205,6 +205,8 @@ static void onstatechange(struct mg_tcpip_if *ifp) {
     MG_INFO(("READY, IP: %M", mg_print_ip4, &ifp->ip));
     MG_INFO(("       GW: %M", mg_print_ip4, &ifp->gw));
     MG_INFO(("      MAC: %M", mg_print_mac, &ifp->mac));
+  } else if (ifp->state == MG_TCPIP_STATE_IP) {
+    MG_ERROR(("Got IP"));
     mg_tcpip_arp_request(ifp, ifp->gw, NULL);  // unsolicited GW ARP request
   } else if (ifp->state == MG_TCPIP_STATE_UP) {
     MG_ERROR(("Link up"));
@@ -355,8 +357,12 @@ static void rx_arp(struct mg_tcpip_if *ifp, struct pkt *pkt) {
   } else if (pkt->arp->op == mg_htons(2)) {
     if (memcmp(pkt->arp->tha, ifp->mac, sizeof(pkt->arp->tha)) != 0) return;
     if (pkt->arp->spa == ifp->gw) {
-      // Got response for the GW ARP request. Set ifp->gwmac
+      // Got response for the GW ARP request. Set ifp->gwmac and IP -> READY
       memcpy(ifp->gwmac, pkt->arp->sha, sizeof(ifp->gwmac));
+      if (ifp->state == MG_TCPIP_STATE_IP) {
+        ifp->state = MG_TCPIP_STATE_READY;
+        onstatechange(ifp);
+      }
     } else {
       struct mg_connection *c = getpeer(ifp->mgr, pkt, false);
       if (c != NULL && c->is_arplooking) {
@@ -431,7 +437,7 @@ static void rx_dhcp_client(struct mg_tcpip_if *ifp, struct pkt *pkt) {
       // assume DHCP server = router until ARP resolves
       memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
       ifp->ip = ip, ifp->gw = gw, ifp->mask = mask;
-      ifp->state = MG_TCPIP_STATE_READY;  // BOUND state
+      ifp->state = MG_TCPIP_STATE_IP;  // BOUND state
       uint64_t rand;
       mg_random(&rand, sizeof(rand));
       srand((unsigned int) (rand + mg_millis()));
@@ -479,7 +485,7 @@ static void rx_dhcp_server(struct mg_tcpip_if *ifp, struct pkt *pkt) {
     res.magic = pkt->dhcp->magic;
     res.xid = pkt->dhcp->xid;
     if (ifp->enable_get_gateway) {
-      ifp->gw = res.yiaddr;
+      ifp->gw = res.yiaddr;  // set gw IP, best-effort gwmac as DHCP server's
       memcpy(ifp->gwmac, pkt->eth->src, sizeof(ifp->gwmac));
     }
     tx_udp(ifp, pkt->eth->src, ifp->ip, mg_htons(67),
@@ -896,12 +902,17 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
 
 #if MG_ENABLE_TCPIP_PRINT_DEBUG_STATS
   if (expired_1000ms) {
-    const char *names[] = {"down", "up", "req", "ready"};
+    const char *names[] = {"down", "up", "req", "ip", "ready"};
     MG_INFO(("Status: %s, IP: %M, rx:%u, tx:%u, dr:%u, er:%u",
              names[ifp->state], mg_print_ip4, &ifp->ip, ifp->nrecv, ifp->nsent,
              ifp->ndrop, ifp->nerr));
   }
 #endif
+  // Handle gw ARP request timeout, order is important
+  if (expired_1000ms && ifp->state == MG_TCPIP_STATE_IP) {
+    ifp->state = MG_TCPIP_STATE_READY; // keep best-effort MAC
+    onstatechange(ifp);
+  }
   // Handle physical interface up/down status
   if (expired_1000ms && ifp->driver->up) {
     bool up = ifp->driver->up(ifp);
@@ -911,11 +922,11 @@ static void mg_tcpip_poll(struct mg_tcpip_if *ifp, uint64_t now) {
       ifp->state = up == false ? MG_TCPIP_STATE_DOWN
                    : ifp->enable_dhcp_client || ifp->ip == 0
                        ? MG_TCPIP_STATE_UP
-                       : MG_TCPIP_STATE_READY;
+                       : MG_TCPIP_STATE_IP;
       onstatechange(ifp);
     } else if (!ifp->enable_dhcp_client && ifp->state == MG_TCPIP_STATE_UP &&
                ifp->ip) {
-      ifp->state = MG_TCPIP_STATE_READY;  // ifp->fn has set an IP
+      ifp->state = MG_TCPIP_STATE_IP;  // ifp->fn has set an IP
       onstatechange(ifp);
     }
     if (ifp->state == MG_TCPIP_STATE_DOWN) MG_ERROR(("Network is down"));
@@ -1031,7 +1042,7 @@ void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
     ifp->mtu = MG_TCPIP_MTU_DEFAULT;
     mgr->extraconnsize = sizeof(struct connstate);
     if (ifp->ip == 0) ifp->enable_dhcp_client = true;
-    memset(ifp->gwmac, 255, sizeof(ifp->gwmac));  // Set to broadcast
+    memset(ifp->gwmac, 255, sizeof(ifp->gwmac));  // Set best-effort to bcast
     mg_random(&ifp->eport, sizeof(ifp->eport));   // Random from 0 to 65535
     ifp->eport |= MG_EPHEMERAL_PORT_BASE;         // Random from
                                            // MG_EPHEMERAL_PORT_BASE to 65535

src/net_builtin.h

@@ -60,8 +60,9 @@ struct mg_tcpip_if {
   uint8_t state;                // Current state
 #define MG_TCPIP_STATE_DOWN 0   // Interface is down
 #define MG_TCPIP_STATE_UP 1     // Interface is up
-#define MG_TCPIP_STATE_REQ 2    // Interface is up and has requested an IP
+#define MG_TCPIP_STATE_REQ 2    // Interface is up, DHCP REQUESTING state
-#define MG_TCPIP_STATE_READY 3  // Interface is up and has an IP assigned
+#define MG_TCPIP_STATE_IP 3     // Interface is up and has an IP assigned
+#define MG_TCPIP_STATE_READY 4  // Interface has fully come up, ready to work
 };
 
 void mg_tcpip_init(struct mg_mgr *, struct mg_tcpip_if *);

tutorials/tcpip/pcap-driver/main.c

@@ -1,7 +1,8 @@
-// Copyright (c) 2022 Cesanta Software Limited
+// Copyright (c) 2022-24 Cesanta Software Limited
 // All rights reserved
 //
-// SNTP example using MIP and pcap driver
+// example using MIP and pcap driver
+// make CFLAGS_EXTRA="-DMG_TLS=MG_TLS_BUILTIN -DDISABLE_DHCP" for "auto-IP"
 
 #include <pcap.h>
 #include "mongoose.h"
@@ -10,7 +11,6 @@
 #define MQTTS_URL "mqtts://mongoose.ws:8883"   // HiveMQ does not TLS1.3
 #define MQTT_TOPIC "mg/rx"                     // Topic to subscribe to
 
-// // Taken from broker.emqx.io
 static const char *s_ca_cert =
     "-----BEGIN CERTIFICATE-----\n"
     "MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAw\n"
@@ -44,29 +44,6 @@ static const char *s_ca_cert =
     "emyPxgcYxn/eR44/KJ4EBs+lVDR3veyJm+kXQ99b21/+jh5Xos1AnX5iItreGCc=\n"
     "-----END CERTIFICATE-----\n";
 
-//     "-----BEGIN CERTIFICATE-----\n"
-//     "MIIDjjCCAnagAwIBAgIQAzrx5qcRqaC7KGSxHQn65TANBgkqhkiG9w0BAQsFADBh"
-//     "MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3\n"
-//     "d3cuZGlnaWNlcnQuY29tMSAwHgYDVQQDExdEaWdpQ2VydCBHbG9iYWwgUm9vdCBH\n"
-//     "MjAeFw0xMzA4MDExMjAwMDBaFw0zODAxMTUxMjAwMDBaMGExCzAJBgNVBAYTAlVT\n"
-//     "MRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5j\n"
-//     "b20xIDAeBgNVBAMTF0RpZ2lDZXJ0IEdsb2JhbCBSb290IEcyMIIBIjANBgkqhkiG\n"
-//     "9w0BAQEFAAOCAQ8AMIIBCgKCAQEAuzfNNNx7a8myaJCtSnX/RrohCgiN9RlUyfuI\n"
-//     "2/Ou8jqJkTx65qsGGmvPrC3oXgkkRLpimn7Wo6h+4FR1IAWsULecYxpsMNzaHxmx\n"
-//     "1x7e/dfgy5SDN67sH0NO3Xss0r0upS/kqbitOtSZpLYl6ZtrAGCSYP9PIUkY92eQ\n"
-//     "q2EGnI/yuum06ZIya7XzV+hdG82MHauVBJVJ8zUtluNJbd134/tJS7SsVQepj5Wz\n"
-//     "tCO7TG1F8PapspUwtP1MVYwnSlcUfIKdzXOS0xZKBgyMUNGPHgm+F6HmIcr9g+UQ\n"
-//     "vIOlCsRnKPZzFBQ9RnbDhxSJITRNrw9FDKZJobq7nMWxM4MphQIDAQABo0IwQDAP\n"
-//     "BgNVHRMBAf8EBTADAQH/MA4GA1UdDwEB/wQEAwIBhjAdBgNVHQ4EFgQUTiJUIBiV\n"
-//     "5uNu5g/6+rkS7QYXjzkwDQYJKoZIhvcNAQELBQADggEBAGBnKJRvDkhj6zHd6mcY\n"
-//     "1Yl9PMWLSn/pvtsrF9+wX3N3KjITOYFnQoQj8kVnNeyIv/iPsGEMNKSuIEyExtv4\n"
-//     "NeF22d+mQrvHRAiGfzZ0JFrabA0UWTW98kndth/Jsw1HKj2ZL7tcu7XUIOGZX1NG\n"
-//     "Fdtom/DzMNU+MeKNhJ7jitralj41E6Vf8PlwUHBHQRFXGU7Aj64GxJUTFy8bJZ91\n"
-//     "8rGOmaFvE7FBcf6IKshPECBV1/MUReXgRPTqh5Uykw7+U0b6LJ3/iyK5S9kJRaTe\n"
-//     "pLiaWN0bfVKfjllDiIGknibVb63dDcY3fe0Dkhvld1927jyNxF1WW6LZZm6zNTfl\n"
-//     "MrY=\n"
-//     "-----END CERTIFICATE-----\n";
-
 static const char *s_tls_cert =
     "-----BEGIN CERTIFICATE-----\n"
     "MIIBMTCB2aADAgECAgkAluqkgeuV/zUwCgYIKoZIzj0EAwIwEzERMA8GA1UEAwwI\n"
@@ -165,8 +142,6 @@ static void http_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
   (void) ev_data;
 }
 
-static struct mg_connection *mqtt_conn = NULL;
-
 static void mqtt_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
   if (ev == MG_EV_OPEN) {
     MG_INFO(("%lu CREATED", c->id));
@@ -191,21 +166,15 @@ static void mqtt_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
              mm->data.buf, (int) mm->topic.len, mm->topic.buf));
   } else if (ev == MG_EV_CLOSE) {
     MG_INFO(("%lu CLOSED", c->id));
-    mqtt_conn = NULL;  // Mark that we're closed
   }
 }
 
 static void if_ev_handler(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
   // Trigger MQTT connection when we have an IP address
-  if (ifp->state == MG_TCPIP_STATE_READY &&
+  if (ifp->state == MG_TCPIP_STATE_READY && ev == MG_TCPIP_EV_ST_CHG) {
-      (ev == MG_TCPIP_EV_ST_CHG || ev == MG_TCPIP_EV_TIMER_1S)) {
     struct mg_mqtt_opts opts = {.clean = true};
-    if (mqtt_conn == NULL) {
+    // mg_mqtt_connect(ifp->mgr, MQTT_URL, &opts, mqtt_ev_handler, NULL);
-      // mqtt_conn = mg_mqtt_connect(ifp->mgr, MQTT_URL, &opts, mqtt_ev_handler,
+    mg_mqtt_connect(ifp->mgr, MQTTS_URL, &opts, mqtt_ev_handler, "tls enabled");
-      // NULL);
-      mqtt_conn = mg_mqtt_connect(ifp->mgr, MQTTS_URL, &opts, mqtt_ev_handler,
-                                  "tls enabled");
-    }
   }
 
 #if defined(DISABLE_DHCP)
@@ -216,9 +185,12 @@ static void if_ev_handler(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
     if (ip == 0) ip = MG_IPV4(169, 254, 2, 100);
 
     // restart process on link change
-    if (ev == MG_TCPIP_EV_ST_CHG && ifp->state == MG_TCPIP_STATE_DOWN)
+    if (ev == MG_TCPIP_EV_ST_CHG && ifp->state == MG_TCPIP_STATE_DOWN) {
       ifp->ip = 0;
+      counter = 0;
+    }
 
+    if (ifp->state == MG_TCPIP_STATE_UP) {
       // Catch ARP packets. Parse them yourself, that's easy.
       if (ev == MG_TCPIP_EV_ARP) {
         struct mg_str *frame = ev_data;
@@ -228,18 +200,19 @@ static void if_ev_handler(struct mg_tcpip_if *ifp, int ev, void *ev_data) {
       }
 
       // Catch 1 second timer events
-    if (ev == MG_TCPIP_EV_TIMER_1S && ifp->state == MG_TCPIP_STATE_UP) {
+      if (ev == MG_TCPIP_EV_TIMER_1S) {
+        if (++counter <= 3) {
           MG_INFO(("Sending ARP probe"));
           mg_tcpip_arp_request(ifp, ip, NULL);
-
+        } else {
           // Seems to be no conflict. Assign us an IP
-      if (counter++ > 2) {
+          MG_INFO(("Assigning %M, sending gratuitous ARP", mg_print_ip4, &ip));
-        MG_INFO(("Assigning %M, sending ARP probe", mg_print_ip4, &ip));
+          ifp->ip = ip;  // state will change to MG_TCPIP_STATE_IP on next poll
-        ifp->ip = ip;  // state will change to MG_TCPIP_STATE_READY on next poll
           mg_tcpip_arp_request(ifp, ip, ifp->mac);
         }
       }
     }
+  }
 #else
   (void) ev_data;
 #endif
@@ -302,17 +275,17 @@ int main(int argc, char *argv[]) {
   struct mg_tcpip_driver driver = {.tx = pcap_tx, .up = pcap_up, .rx = pcap_rx};
   struct mg_tcpip_if mif = {.driver = &driver,
                             .driver_data = ph,
+                            .enable_mac_check = true,
 #if defined(DISABLE_DHCP)
                             .mask = MG_IPV4(255, 255, 255, 0),
-                            .gw = MG_IPV4(169, 254, 2, 1)
+                            .gw = MG_IPV4(169, 254, 2, 1),
 #endif
-};
+                            .fn = if_ev_handler};
   sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", &mif.mac[0], &mif.mac[1],
          &mif.mac[2], &mif.mac[3], &mif.mac[4], &mif.mac[5]);
   mg_tcpip_init(&mgr, &mif);
 
-  // Call order is important: call after mg_tcpip_init()
+  // order is important: set after calling mg_tcpip_init()
-  mif.fn = if_ev_handler;
 #if defined(DISABLE_DHCP)
   mif.enable_dhcp_client = false;
 #endif