[http_request] Fix infinite loop when server doesn't send Content-Length header (#12480)

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

esphome/components/http_request/http_request.h

@@ -255,6 +255,9 @@ template<typename... Ts> class HttpRequestSendAction : public Action<Ts...> {
         size_t read_index = 0;
         while (container->get_bytes_read() < max_length) {
           int read = container->read(buf + read_index, std::min<size_t>(max_length - read_index, 512));
+          if (read <= 0) {
+            break;
+          }
           App.feed_wdt();
           yield();
           read_index += read;

esphome/components/http_request/ota/ota_http_request.cpp

@@ -132,11 +132,18 @@ uint8_t OtaHttpRequestComponent::do_ota_() {
     App.feed_wdt();
     yield();
 
-    if (bufsize < 0) {
-      ESP_LOGE(TAG, "Stream closed");
-      this->cleanup_(std::move(backend), container);
-      return OTA_CONNECTION_ERROR;
-    } else if (bufsize > 0 && bufsize <= OtaHttpRequestComponent::HTTP_RECV_BUFFER) {
+    // Exit loop if no data available (stream closed or end of data)
+    if (bufsize <= 0) {
+      if (bufsize < 0) {
+        ESP_LOGE(TAG, "Stream closed with error");
+        this->cleanup_(std::move(backend), container);
+        return OTA_CONNECTION_ERROR;
+      }
+      // bufsize == 0: no more data available, exit loop
+      break;
+    }
+
+    if (bufsize <= OtaHttpRequestComponent::HTTP_RECV_BUFFER) {
       // add read bytes to MD5
       md5_receive.add(buf, bufsize);
 
@@ -247,6 +254,9 @@ bool OtaHttpRequestComponent::http_get_md5_() {
   int read_len = 0;
   while (container->get_bytes_read() < MD5_SIZE) {
     read_len = container->read((uint8_t *) this->md5_expected_.data(), MD5_SIZE);
+    if (read_len <= 0) {
+      break;
+    }
     App.feed_wdt();
     yield();
   }

esphome/components/http_request/update/http_request_update.cpp

@@ -76,6 +76,11 @@ void HttpRequestUpdate::update_task(void *params) {
 
     yield();
 
+    if (read_bytes <= 0) {
+      // Network error or connection closed - break to avoid infinite loop
+      break;
+    }
+
     read_index += read_bytes;
   }