fix: oom exceptions for OPDS, KOSync, and OTA via wolfssl (#2475)

src/util/UrlUtils.cpp

@@ -1,6 +1,29 @@
 #include "UrlUtils.h"
 
+#include <cstdio>
+
 namespace UrlUtils {
+namespace {
+bool isHexDigit(const char c) { return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f'); }
+
+bool shouldEncode(const unsigned char c) {
+  if (c <= 0x20 || c >= 0x7f) return true;
+  switch (c) {
+    case '"':
+    case '<':
+    case '>':
+    case '\\':
+    case '^':
+    case '`':
+    case '{':
+    case '|':
+    case '}':
+      return true;
+    default:
+      return false;
+  }
+}
+}  // namespace
 
 std::string ensureProtocol(const std::string& url) {
   if (url.find("://") == std::string::npos) {
@@ -22,18 +45,39 @@ std::string extractHost(const std::string& url) {
   return pathStart == std::string::npos ? url : url.substr(0, pathStart);
 }
 
+std::string encodeUnsafeUrlChars(const std::string& url) {
+  std::string out;
+  out.reserve(url.size());
+  for (size_t i = 0; i < url.size(); ++i) {
+    const unsigned char c = static_cast<unsigned char>(url[i]);
+    if (c == '%' && i + 2 < url.size() && isHexDigit(url[i + 1]) && isHexDigit(url[i + 2])) {
+      out += url[i];
+      out += url[i + 1];
+      out += url[i + 2];
+      i += 2;
+    } else if (c == '%' || shouldEncode(c)) {
+      char encoded[4];
+      snprintf(encoded, sizeof(encoded), "%%%02X", c);
+      out += encoded;
+    } else {
+      out += static_cast<char>(c);
+    }
+  }
+  return out;
+}
+
 std::string buildUrl(const std::string& serverUrl, const std::string& path) {
   // If path is already an absolute URL (has protocol), use it directly
   if (path.find("://") != std::string::npos) {
-    return path;
+    return encodeUnsafeUrlChars(path);
   }
   const std::string urlWithProtocol = ensureProtocol(serverUrl);
   if (path.empty()) {
-    return urlWithProtocol;
+    return encodeUnsafeUrlChars(urlWithProtocol);
   }
   if (path[0] == '/') {
     // Absolute path - use just the host
-    return extractHost(urlWithProtocol) + path;
+    return encodeUnsafeUrlChars(extractHost(urlWithProtocol) + path);
   }
   // Relative path - strip query string from base before appending
   std::string base = urlWithProtocol;
@@ -42,9 +86,9 @@ std::string buildUrl(const std::string& serverUrl, const std::string& path) {
     base.resize(queryPos);
   }
   if (base.back() == '/') {
-    return base + path;
+    return encodeUnsafeUrlChars(base + path);
   }
-  return base + "/" + path;
+  return encodeUnsafeUrlChars(base + "/" + path);
 }
 
 }  // namespace UrlUtils

src/util/UrlUtils.h

@@ -13,6 +13,11 @@ std::string ensureProtocol(const std::string& url);
  */
 std::string extractHost(const std::string& url);
 
+/**
+ * Percent-encode raw characters that esp_http_client rejects in a URL.
+ */
+std::string encodeUnsafeUrlChars(const std::string& url);
+
 /**
  * Build full URL from server URL and path.
  * If path starts with /, it's an absolute path from the host root.