esp_http_client: fix truncated headers

Signed-off-by: yuanjm <yuanjianmin@espressif.com>

Merges https://github.com/espressif/esp-idf/pull/6370

components/esp_http_client/lib/http_utils.c

@@ -61,6 +61,30 @@ char *http_utils_assign_string(char **str, const char *new_str, int len)
     return old_str;
 }
 
+char *http_utils_append_string(char **str, const char *new_str, int len)
+{
+    if (new_str == NULL) {
+        return NULL;
+    }
+    char *old_str = *str;
+    if (len <= 0) {
+        len = strlen(new_str);
+    }
+    if (old_str) {
+        int old_len = strlen(old_str);
+        old_str = realloc(old_str, old_len + len + 1);
+        mem_check(old_str);
+        memcpy(old_str + old_len, new_str, len);
+        old_str[old_len + len] = 0;
+    } else {
+        old_str = calloc(1, len + 1);
+        mem_check(old_str);
+        memcpy(old_str, new_str, len);
+    }
+    *str = old_str;
+    return old_str;
+}
+
 void http_utils_trim_whitespace(char **str)
 {
     char *end, *start;

components/esp_http_client/lib/include/http_utils.h

@@ -30,6 +30,19 @@
  */
 char *http_utils_assign_string(char **str, const char *new_str, int len);
 
+/**
+ * @brief      Realloc *str and append new_str to it, if not NULL; assign new_str to *str pointer if NULL
+ *
+ * @param      str      pointer to string pointer
+ * @param      new_str  assign this string to str
+ * @param      len      length of string, 0 if new_str is zero terminated
+ *
+ * @return
+ *  - new_str pointer
+ *  - NULL
+ */
+char *http_utils_append_string(char **str, const char *new_str, int len);
+
 /**
  * @brief      Remove white space at begin and end of string
  *