MQTT parsing fix

PUBLISHED_FROM=41f43cb0e707259740de3346308f746c2a3778fd

examples/mqtt_client/mqtt_client.c

@@ -20,8 +20,8 @@
 static const char *s_address = "localhost:1883";
 static const char *s_user_name = NULL;
 static const char *s_password = NULL;
-
-struct mg_mqtt_topic_expression topic_expressions[] = {{"/stuff", 0}};
+static const char *s_topic = "/stuff";
+static struct mg_mqtt_topic_expression s_topic_expr = {NULL, 0};
 
 static void ev_handler(struct mg_connection *nc, int ev, void *p) {
   struct mg_mqtt_message *msg = (struct mg_mqtt_message *) p;
@@ -48,10 +48,9 @@ static void ev_handler(struct mg_connection *nc, int ev, void *p) {
         printf("Got mqtt connection error: %d\n", msg->connack_ret_code);
         exit(1);
       }
-      printf("Subscribing to '/stuff'\n");
-      mg_mqtt_subscribe(nc, topic_expressions,
-                        sizeof(topic_expressions) / sizeof(*topic_expressions),
-                        42);
+      s_topic_expr.topic = s_topic;
+      printf("Subscribing to '%s'\n", s_topic);
+      mg_mqtt_subscribe(nc, &s_topic_expr, 1, 42);
       break;
     case MG_EV_MQTT_PUBACK:
       printf("Message publishing acknowledged (msg_id: %d)\n", msg->message_id);
@@ -89,14 +88,13 @@ int main(int argc, char **argv) {
   /* Parse command line arguments */
   for (i = 1; i < argc; i++) {
     if (strcmp(argv[i], "-h") == 0) {
-      s_address = argv[i + 1];
-      i++;
+      s_address = argv[++i];
     } else if (strcmp(argv[i], "-u") == 0) {
-      s_user_name = argv[i + 1];
-      i++;
+      s_user_name = argv[++i];
+    } else if (strcmp(argv[i], "-t") == 0) {
+      s_topic = argv[++i];
     } else if (strcmp(argv[i], "-p") == 0) {
-      s_password = argv[i + 1];
-      i++;
+      s_password = argv[++i];
     }
   }
 

mongoose.c

@@ -9541,10 +9541,15 @@ void mg_basic_auth_header(const char *user, const char *pass,
 /* Amalgamated: #include "mongoose/src/internal.h" */
 /* Amalgamated: #include "mongoose/src/mqtt.h" */
 
+static uint16_t getu16(const char *p) {
+  const uint8_t *up = (const uint8_t *) p;
+  return (up[0] << 8) + up[1];
+}
+
 static const char *scanto(const char *p, struct mg_str *s) {
-  s->len = ntohs(*(uint16_t *) p);
+  s->len = getu16(p);
   s->p = p + 2;
-  return p + 2 + s->len;
+  return s->p + s->len;
 }
 
 MG_INTERNAL int parse_mqtt(struct mbuf *io, struct mg_mqtt_message *mm) {
@@ -9575,7 +9580,7 @@ MG_INTERNAL int parse_mqtt(struct mbuf *io, struct mg_mqtt_message *mm) {
       p = scanto(p, &mm->protocol_name);
       mm->protocol_version = *(uint8_t *) p++;
       mm->connect_flags = *(uint8_t *) p++;
-      mm->keep_alive_timer = ntohs(*(uint16_t *) p);
+      mm->keep_alive_timer = getu16(p);
       p += 2;
       if (p < end) p = scanto(p, &mm->client_id);
       if (p < end && (mm->connect_flags & MG_MQTT_HAS_WILL))
@@ -9606,11 +9611,11 @@ MG_INTERNAL int parse_mqtt(struct mbuf *io, struct mg_mqtt_message *mm) {
     case MG_MQTT_CMD_PUBREL:
     case MG_MQTT_CMD_PUBCOMP:
     case MG_MQTT_CMD_SUBACK:
-      mm->message_id = ntohs(*(uint16_t *) p);
+      mm->message_id = getu16(p);
       break;
     case MG_MQTT_CMD_PUBLISH: {
       if (MG_MQTT_GET_QOS(header) > 0) {
-        mm->message_id = ntohs(*(uint16_t *) io->buf);
+        mm->message_id = getu16(p);
         p += 2;
       }
       p = scanto(p, &mm->topic);
@@ -9620,7 +9625,7 @@ MG_INTERNAL int parse_mqtt(struct mbuf *io, struct mg_mqtt_message *mm) {
       break;
     }
     case MG_MQTT_CMD_SUBSCRIBE:
-      mm->message_id = ntohs(*(uint16_t *) p);
+      mm->message_id = getu16(p);
       p += 2;
       /*
        * topic expressions are left in the payload and can be parsed with