nitpicks

tutorials/tcp/modbus-dashboard/net.c

@@ -125,7 +125,7 @@ static struct mg_connection *start_modbus_request(struct mg_mgr *mgr,
   } else {
     send16(c, 1);  // TID. Use random?
     send16(c, 0);  // Protocol identifier: 0 (modbus)
-    uint16_t *lp = (uint16_t *) &c->send.buf[c->send.len];
+    size_t lp = c->send.len;
     send16(c, 0);  // Length: to be set later
     size_t len = c->send.len;
 
@@ -151,7 +151,8 @@ static struct mg_connection *start_modbus_request(struct mg_mgr *mgr,
       send8(c, 0);   // Object ID: 0 (vendor name)
     }
 
-    *lp = mg_htons((uint16_t) (c->send.len - len));  // Set length field
+    uint16_t length = mg_htons((uint16_t) (c->send.len - len));
+    memcpy(c->send.buf + lp, &length, sizeof(length));  // Set length field
     mg_hexdump(c->send.buf, c->send.len);
     MG_INFO(("%lu SENDING %lu", c->id, c->send.len));
 

tutorials/udp/captive-dns-server/main.c

@@ -25,10 +25,11 @@ static void fn(struct mg_connection *c, int ev, void *ev_data) {
     c->is_hexdumping = 1;
   } else if (ev == MG_EV_READ) {
     struct mg_dns_rr rr;  // Parse first question, offset 12 is header size
+    char buf[512];
     size_t n = mg_dns_parse_rr(c->recv.buf, c->recv.len, 12, true, &rr);
     MG_INFO(("DNS request parsed, result=%d", (int) n));
-    if (n > 0) {
-      char buf[512];
+    if (n > 0 &&
+        n <= sizeof(buf) - sizeof(struct mg_dns_header) - sizeof(answer)) {
       struct mg_dns_header *h = (struct mg_dns_header *) buf;
       memset(buf, 0, sizeof(buf));  // Clear the whole datagram
       h->txnid = ((struct mg_dns_header *) c->recv.buf)->txnid;  // Copy tnxid