#53 - fix

Author: dedok

src/json_encoders.c

@@ -59,7 +59,7 @@ json_encode_string(
     const char *str, size_t str_len,
     bool escape_solidus)
 {
-    if (!buf || !*buf || !buf_len || !str || !str_len)
+    if (!buf || !buf_len)
         return "json_encode_string: invalid arguments";
 
     char hex_buf[7];
@@ -69,41 +69,43 @@ json_encode_string(
     if (!append_ch(buf, &buf_len, '\"'))
         goto oom;
 
-    for (;str_len != 0; --str_len, ++str) {
-
-        const char ch = *str;
-        const char *escaped = NULL;
-
-        switch (ch) {
-        case '\r': escaped = "\\r"; break;
-        case '\n': escaped = "\\n"; break;
-        case '\\': escaped = "\\\\"; break;
-        /* it is not required to escape a solidus in JSON:
-         * read sec. 2.5: http://www.ietf.org/rfc/rfc4627.txt
-         * specifically, this production from the grammar:
-         *   unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
-         */
-        case '/': if (escape_solidus) escaped = "\\/"; break;
-        case '"': escaped = "\\\""; break;
-        case '\f': escaped = "\\f"; break;
-        case '\b': escaped = "\\b"; break;
-        case '\t': escaped = "\\t"; break;
-        default:
-            if ((unsigned char) ch < 32) {
-                char_to_hex(hex_buf + 4, ch);
-                escaped = hex_buf;
+    if (str) {
+        for (;str_len != 0; --str_len, ++str) {
+
+            const char ch = *str;
+            const char *escaped = NULL;
+
+            switch (ch) {
+            case '\r': escaped = "\\r"; break;
+            case '\n': escaped = "\\n"; break;
+            case '\\': escaped = "\\\\"; break;
+            /* it is not required to escape a solidus in JSON:
+             * read sec. 2.5: http://www.ietf.org/rfc/rfc4627.txt
+             * specifically, this production from the grammar:
+             *   unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
+             */
+            case '/': if (escape_solidus) escaped = "\\/"; break;
+            case '"': escaped = "\\\""; break;
+            case '\f': escaped = "\\f"; break;
+            case '\b': escaped = "\\b"; break;
+            case '\t': escaped = "\\t"; break;
+            default:
+                if ((unsigned char) ch < 32) {
+                    char_to_hex(hex_buf + 4, ch);
+                    escaped = hex_buf;
+                }
+                break;
+            } /* switch */
+
+            if (escaped) {
+                if (!append_str(buf, &buf_len, escaped, strlen(escaped)))
+                    goto oom;
+            } else {
+                if (!append_ch(buf, &buf_len, ch))
+                    goto oom;
             }
-            break;
-        } /* switch */
-
-        if (escaped) {
-            if (!append_str(buf, &buf_len, escaped, strlen(escaped)))
-                goto oom;
-        } else {
-            if (!append_ch(buf, &buf_len, ch))
-                goto oom;
-        }
-    } /* for */
+        } /* for */
+    } /* if */
 
     if (!append_ch(buf, &buf_len, '\"'))
         goto oom;

test/test.lua

@@ -88,3 +88,7 @@ function issue_44(request)
   return c.a.b
 end
 -- ]]
+
+function four_empty_strings()
+  return {"", "", "", "", {a = ""}}
+end

test/v23_features.py

@@ -117,3 +117,10 @@
 result = post_success(preset_method_location, {
     'method':'echo_2', 'params':[data], 'id': 1}, {})
 assert(data == result[0]), 'not equal'
+
+#===========
+#
+print('[+] Empty string')
+preset_method_location = BASE_URL + '/tnt'
+post_success(preset_method_location, {
+    'method':'four_empty_strings', 'params':[], 'id': 1}, {})