fix(node): validate & sanitize node name

src/helpers/CommonCLI.cpp

@@ -59,7 +59,16 @@ void CommonCLI::loadPrefsInt(FILESYSTEM* fs, const char* filename) {
     file.read((uint8_t *) &_prefs->flood_advert_interval, sizeof(_prefs->flood_advert_interval));  // 125
     file.read((uint8_t *) &_prefs->interference_threshold, sizeof(_prefs->interference_threshold));  // 126
 
-    // sanitise bad pref values
+    // sanitize loaded node_name to printable ASCII (defense against legacy invalid values)
+    {
+      char filtered[sizeof(_prefs->node_name)];
+      StrHelper::filterToPrintableASCII(filtered, _prefs->node_name, sizeof(filtered));
+      if (strcmp(filtered, _prefs->node_name) != 0) {
+        StrHelper::strncpy(_prefs->node_name, filtered, sizeof(_prefs->node_name));
+      }
+    }
+
+    // sanitise bad pref numeric values
     _prefs->rx_delay_base = constrain(_prefs->rx_delay_base, 0, 20.0f);
     _prefs->tx_delay_factor = constrain(_prefs->tx_delay_factor, 0, 2.0f);
     _prefs->direct_tx_delay_factor = constrain(_prefs->direct_tx_delay_factor, 0, 2.0f);
@@ -313,9 +322,17 @@ void CommonCLI::handleCommand(uint32_t sender_timestamp, const char* command, ch
           strcpy(reply, "Error, invalid key");
         }
       } else if (memcmp(config, "name ", 5) == 0) {
-        StrHelper::strncpy(_prefs->node_name, &config[5], sizeof(_prefs->node_name));
-        savePrefs();
-        strcpy(reply, "OK");
+        const char* new_name = &config[5];
+        size_t n = strlen(new_name);
+        if (n == 0 || n >= sizeof(_prefs->node_name)) {
+          strcpy(reply, "Error: name length must be 1-31");
+        } else if (!StrHelper::isPrintableASCII(new_name)) {
+          strcpy(reply, "Error: name must be printable ASCII (0x20-0x7E)");
+        } else {
+          StrHelper::strncpy(_prefs->node_name, new_name, sizeof(_prefs->node_name));
+          savePrefs();
+          strcpy(reply, "OK");
+        }
       } else if (memcmp(config, "repeat ", 7) == 0) {
         _prefs->disable_fwd = memcmp(&config[7], "off", 3) == 0;
         savePrefs();

src/helpers/ESP32Board.cpp

@@ -10,16 +10,44 @@
 
 #include <SPIFFS.h>
 
+static void htmlEscape(char* dest, size_t dest_sz, const char* src) {
+  if (dest_sz == 0) return;
+  size_t i = 0;
+  for (; *src && i + 1 < dest_sz; ++src) {
+    const char* rep = nullptr;
+    switch (*src) {
+      case '&': rep = "&amp;"; break;
+      case '<': rep = "&lt;";  break;
+      case '>': rep = "&gt;";  break;
+      case '"': rep = "&quot;"; break;
+      case 39: rep = "&#39;"; break; // '\''
+      default: rep = nullptr; break;
+    }
+    if (rep) {
+      for (const char* p = rep; *p && i + 1 < dest_sz; ++p) dest[i++] = *p;
+    } else {
+      dest[i++] = *src;
+    }
+  }
+  dest[i] = 0;
+}
+
 bool ESP32Board::startOTAUpdate(const char* id, char reply[]) {
   WiFi.softAP("MeshCore-OTA", NULL);
 
   sprintf(reply, "Started: http://%s/update", WiFi.softAPIP().toString().c_str());
   MESH_DEBUG_PRINTLN("startOTAUpdate: %s", reply);
 
-  static char id_buf[60];
-  sprintf(id_buf, "%s (%s)", id, getManufacturerName());
-  static char home_buf[90];
-  sprintf(home_buf, "<H2>Hi! I am a MeshCore Repeater. ID: %s</H2>", id);
+  // HTML-escape dynamic values to avoid breaking the page with special chars
+  static char id_safe[128];
+  static char man_safe[64];
+  htmlEscape(id_safe, sizeof(id_safe), id);
+  htmlEscape(man_safe, sizeof(man_safe), getManufacturerName());
+
+  static char id_buf[200];
+  snprintf(id_buf, sizeof(id_buf), "%s (%s)", id_safe, man_safe);
+  static char home_buf[240];
+  snprintf(home_buf, sizeof(home_buf), "<H2>Hi! I am a MeshCore Repeater. ID: %s</H2>", id_safe);
 
   AsyncWebServer* server = new AsyncWebServer(80);
 

src/helpers/TxtDataHelpers.cpp

@@ -19,6 +19,30 @@ void StrHelper::strzcpy(char* dest, const char* src, size_t buf_sz) {
   }
 }
 
+bool StrHelper::isPrintableASCII(const char* s) {
+  if (!s) return false;
+  while (*s) {
+    unsigned char c = static_cast<unsigned char>(*s++);
+    if (c < 0x20 || c > 0x7E) return false;
+  }
+  return true;
+}
+
+void StrHelper::filterToPrintableASCII(char* dest, const char* src, size_t buf_sz) {
+  if (buf_sz == 0) return;
+  if (!src) { *dest = 0; return; }
+  while (buf_sz > 1 && *src) {
+    unsigned char c = static_cast<unsigned char>(*src++);
+    if (c >= 0x20 && c <= 0x7E) {
+      *dest++ = (char)c;
+    } else {
+      *dest++ = '_';
+    }
+    buf_sz--;
+  }
+  *dest = 0;
+}
+
 #include <Arduino.h>
 
 union int32_Float_t 

src/helpers/TxtDataHelpers.h

@@ -11,5 +11,9 @@ class StrHelper {
 public:
   static void strncpy(char* dest, const char* src, size_t buf_sz);
   static void strzcpy(char* dest, const char* src, size_t buf_sz);   // pads with trailing nulls
+  // Returns true if all characters are printable ASCII (0x20-0x7E)
+  static bool isPrintableASCII(const char* s);
+  // Copy src to dest, replacing non-printable ASCII bytes with '_'. Always null-terminates.
+  static void filterToPrintableASCII(char* dest, const char* src, size_t buf_sz);
   static const char* ftoa(float f);
 };