Make mip-pcap work on Mac

examples/mip-pcap/README.md

@@ -0,0 +1,47 @@
+#MIP TCP / IP stack over pcap
+
+This example allows to use Mongoose's MIP built-in TCP/IP stack on systems
+that support pcap API, i.e. have libpcap library installed. The application
+opens an interface and uses `pcap_next_ex()` for reading packets from the
+interface, and `pcap_inject()` to write packets to the interface.
+
+NOTE: depending on the libcap implementation, the injected packets may
+or may not be looped back to the interface's TCP/IP stack. If they are
+not looped back, then it is necessary to create a separate interface that
+is bridged to the target interface - see MacOS example below.
+
+## MacOS setup
+
+MacOS has support for `feth` (fake ethernet) interfaces. One can create a pair
+of `feth` interfaces and interlink them. Once a `feth` interface is assigned
+a peer and an IP address, anything that gets injected to it, appears on a
+peer interface and vice versa.
+
+```sh
+$ sudo ifconfig feth0 create
+$ sudo ifconfig feth1 create
+$ sudo ifconfig feth1 peer feth 0     # Link two fake ethernet ifaces together
+$ sudo ifconfig feth1 10.10           # Assign 10.0.0.10 to feth1
+$ sudo ifconfig feth0 up
+$ sudo ifconfig feth1 up
+```
+
+Now we have two Ethernet interfaces, `feth0` and `feth1`, interlinked and active.
+On your Mac, go to "System Preferences" / Sharing, enable "Internet Sharing"
+and choose "Thunderbolt bridge". This enables DHCP on the `bridge0` interface.
+On my system it gets `192.168.2.1` IP address, and serves `192.168.2/24` net.
+which is bridge for all Thunderbolt devices, and adds necessary routes to the
+WiFi interface. We should add one of our fake interfaces to this bridge:
+
+```sh
+$ sudo ifconfig bridge0 addm feth1
+```
+
+We cat start an example using the `feth0`:
+
+```sh
+$ make -C examples/mip-pcap/ clean all ARGS="-i feth0" 
+...
+2386718 3 mip.c:279:arp_cache_add       ARP cache: added 0xc0a80201 @ 36:77:4d:be:e0:80
+2386718 2 mip.c:300:onstatechange       READY, IP: 192.168.2.17
+```

examples/mip-pcap/main.c

@@ -6,45 +6,22 @@
 #include <pcap.h>
 #include "mongoose.h"
 
-static struct mg_connection *s_sntp_conn = NULL;
+#define MQTT_URL "mqtt://broker.hivemq.com:1883"  // MQTT broker to connect to
+#define MQTT_TOPIC "t/123"                        // Topic to subscribe to
 
 static int s_signo;
 void signal_handler(int signo) {
   s_signo = signo;
 }
 
-// SNTP client callback
-static void sfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
-  if (ev == MG_EV_SNTP_TIME) {
-    int64_t t = *(int64_t *) ev_data;
-    MG_INFO(("Got SNTP time: %lld ms from epoch", t));
-  } else if (ev == MG_EV_CLOSE) {
-    s_sntp_conn = NULL;
-  }
-  (void) fn_data, (void) c;
-}
-
-// Called every 5 seconds. Increase that for production case.
-static void timer_fn(void *arg) {
-  struct mg_mgr *mgr = (struct mg_mgr *) arg;
-  if (s_sntp_conn == NULL) s_sntp_conn = mg_sntp_connect(mgr, NULL, sfn, NULL);
-  if (s_sntp_conn != NULL) mg_sntp_request(s_sntp_conn);
-}
-
-static int fail(const char *fmt, ...) {
-  va_list ap;
-  va_start(ap, fmt);
-  vfprintf(stderr, fmt, ap);
-  va_end(ap);
-  return EXIT_FAILURE;
-}
-
-static size_t pcap_tx(const void *data, size_t len, void *userdata) {
-  int res = pcap_inject((pcap_t *) userdata, data, len);
+static size_t pcap_tx(const void *buf, size_t len, void *userdata) {
+  int res = pcap_inject((pcap_t *) userdata, buf, len);
   if (res == PCAP_ERROR) {
     MG_ERROR(("pcap_inject: %d", res));
   }
-  return len;
+  MG_INFO(("TX %lu", len));
+  // mg_hexdump(buf, len);
+  return res == PCAP_ERROR ? 0 : len;
 }
 
 static bool pcap_up(void *userdata) {
@@ -58,21 +35,43 @@ static size_t pcap_rx(void *buf, size_t len, void *userdata) {
   if (pcap_next_ex((pcap_t *) userdata, &hdr, &pkt) == 1) {
     received = hdr->len < len ? hdr->len : len;
     memcpy(buf, pkt, received);
+    MG_INFO(("RX %lu", received));
+    // mg_hexdump(buf, received);
   }
   return received;
 }
 
+static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
+  if (ev == MG_EV_HTTP_MSG) mg_http_reply(c, 200, NULL, "hi\n");
+  (void) fn_data, (void) ev_data;
+}
+
+// MQTT event handler function
+static void mfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
+  if (ev == MG_EV_CONNECT && mg_url_is_ssl(MQTT_URL)) {
+    struct mg_tls_opts opts = {.ca = "ca.pem",
+                               .srvname = mg_url_host(MQTT_URL)};
+    mg_tls_init(c, &opts);
+  } else if (ev == MG_EV_MQTT_OPEN) {
+    c->is_hexdumping = 1;
+    mg_mqtt_sub(c, mg_str(MQTT_TOPIC), 2);
+  } else if (ev == MG_EV_MQTT_MSG) {
+    struct mg_mqtt_message *mm = ev_data;
+    MG_INFO(("%.*s", (int) mm->data.len, mm->data.ptr));
+  } else if (ev == MG_EV_MQTT_CMD) {
+    struct mg_mqtt_message *mm = (struct mg_mqtt_message *) ev_data;
+    MG_DEBUG(("cmd %d qos %d", mm->cmd, mm->qos));
+  } else if (ev == MG_EV_CLOSE) {
+  }
+  (void) fn_data;
+}
+
 int main(int argc, char *argv[]) {
   const char *iface = "lo0";              // Network iface
-  const char *mac = "aa:bb:cc:01:02:03";  // MAC address
+  const char *mac = "00:00:01:02:03:77";  // MAC address
   const char *bpf = NULL;  // "host x.x.x.x or ether host ff:ff:ff:ff:ff:ff";
   char errbuf[PCAP_ERRBUF_SIZE] = "";
 
-  struct mg_mgr mgr;        // Event manager
-  mg_mgr_init(&mgr);        // Initialise event manager
-  mg_log_set(MG_LL_DEBUG);  // Set debug log level
-  mg_timer_add(&mgr, 3000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn, &mgr);
-
   // Parse options
   for (int i = 1; i < argc; i++) {
     if (strcmp(argv[i], "-i") == 0 && i + 1 < argc) {
@@ -82,7 +81,8 @@ int main(int argc, char *argv[]) {
     } else if (strcmp(argv[i], "-bpf") == 0 && i + 1 < argc) {
       bpf = argv[++i];
     } else {
-      return fail("unknown option %s", argv[i]);
+      MG_ERROR(("unknown option %s", argv[i]));
+      return EXIT_FAILURE;
     }
   }
 
@@ -97,21 +97,27 @@ int main(int argc, char *argv[]) {
       }
       pcap_freealldevs(devs);
     }
-    fail("pcap_open_live: %s\n", errbuf);
+    return EXIT_FAILURE;
   }
   pcap_setnonblock(ph, 1, errbuf);
+  pcap_setdirection(ph, PCAP_D_IN);
+
   // Apply BPF to reduce noise. Let in only broadcasts and our own traffic
   if (bpf != NULL) {
     struct bpf_program bpfp;
-    if (pcap_compile(ph, &bpfp, bpf, 1, 0)) fail("compile \n");
+    if (pcap_compile(ph, &bpfp, bpf, 1, 0)) MG_ERROR(("BPF compile failed\n"));
     pcap_setfilter(ph, &bpfp);
     pcap_freecode(&bpfp);
   }
-  MG_INFO(("Opened interface %s\n", iface));
 
+  MG_INFO(("Opened interface %s", iface));
   signal(SIGINT, signal_handler);
   signal(SIGTERM, signal_handler);
 
+  struct mg_mgr mgr;        // Event manager
+  mg_mgr_init(&mgr);        // Initialise event manager
+  mg_log_set(MG_LL_DEBUG);  // Set debug log level
+
   struct mip_cfg c = {.ip = 0, .mask = 0, .gw = 0};
   sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx", &c.mac[0], &c.mac[1], &c.mac[2],
          &c.mac[3], &c.mac[4], &c.mac[5]);
@@ -120,6 +126,11 @@ int main(int argc, char *argv[]) {
   mip_init(&mgr, &c, &driver, ph);
   MG_INFO(("Init done, starting main loop"));
 
+  mg_http_listen(&mgr, "http://0.0.0.0:8000", fn, NULL);
+
+  struct mg_mqtt_opts opts = {0};
+  // mg_mqtt_connect(&mgr, MQTT_URL, &opts, mfn, NULL);
+
   while (s_signo == 0) mg_mgr_poll(&mgr, 1);  // Infinite event loop
 
   mg_mgr_free(&mgr);