add a query string helper from byte cursor directly (#1080)

include/aws/common/uri.h

@@ -114,6 +114,28 @@ AWS_COMMON_API uint16_t aws_uri_port(const struct aws_uri *uri);
  */
 AWS_COMMON_API const struct aws_byte_cursor *aws_uri_path_and_query(const struct aws_uri *uri);
 
+/**
+ * For iterating over the params in the query string.
+ * `param` is an in/out argument used to track progress, it MUST be zeroed out to start.
+ * If true is returned, `param` contains the value of the next param.
+ * If false is returned, there are no further params.
+ *
+ * Edge cases:
+ * 1) Entries without '=' sign are treated as having a key and no value.
+ *    Example: First param in query string "a&b=c" has key="a" value=""
+ *
+ * 2) Blank entries are skipped.
+ *    Example: The only param in query string "&&a=b" is key="a" value="b"
+ */
+AWS_COMMON_API bool aws_query_string_next_param(struct aws_byte_cursor query_string, struct aws_uri_param *param);
+
+/**
+ * Parses query string and stores the parameters in 'out_params'. Returns AWS_OP_SUCCESS on success and
+ * AWS_OP_ERR on failure. The user is responsible for initializing out_params with item size of struct aws_query_param.
+ * The user is also responsible for cleaning up out_params when finished.
+ */
+AWS_COMMON_API int aws_query_string_params(struct aws_byte_cursor query_string, struct aws_array_list *out_params);
+
 /**
  * For iterating over the params in the uri query string.
  * `param` is an in/out argument used to track progress, it MUST be zeroed out to start.

source/uri.c

@@ -212,7 +212,7 @@ uint16_t aws_uri_port(const struct aws_uri *uri) {
     return uri->port;
 }
 
-bool aws_uri_query_string_next_param(const struct aws_uri *uri, struct aws_uri_param *param) {
+bool aws_query_string_next_param(struct aws_byte_cursor query_string, struct aws_uri_param *param) {
     /* If param is zeroed, then this is the first run. */
     bool first_run = param->value.ptr == NULL;
 
@@ -230,7 +230,7 @@ bool aws_uri_query_string_next_param(const struct aws_uri *uri, struct aws_uri_p
 
     /* The do-while is to skip over any empty substrings */
     do {
-        if (!aws_byte_cursor_next_split(&uri->query_string, '&', &substr)) {
+        if (!aws_byte_cursor_next_split(&query_string, '&', &substr)) {
             /* no more splits, done iterating */
             return false;
         }
@@ -252,10 +252,10 @@ bool aws_uri_query_string_next_param(const struct aws_uri *uri, struct aws_uri_p
     return true;
 }
 
-int aws_uri_query_string_params(const struct aws_uri *uri, struct aws_array_list *out_params) {
+int aws_query_string_params(struct aws_byte_cursor query_string_cursor, struct aws_array_list *out_params) {
     struct aws_uri_param param;
     AWS_ZERO_STRUCT(param);
-    while (aws_uri_query_string_next_param(uri, &param)) {
+    while (aws_query_string_next_param(query_string_cursor, &param)) {
         if (aws_array_list_push_back(out_params, &param)) {
             return AWS_OP_ERR;
         }
@@ -264,6 +264,14 @@ int aws_uri_query_string_params(const struct aws_uri *uri, struct aws_array_list
     return AWS_OP_SUCCESS;
 }
 
+bool aws_uri_query_string_next_param(const struct aws_uri *uri, struct aws_uri_param *param) {
+    return aws_query_string_next_param(uri->query_string, param);
+}
+
+int aws_uri_query_string_params(const struct aws_uri *uri, struct aws_array_list *out_params) {
+    return aws_query_string_params(uri->query_string, out_params);
+}
+
 static void s_parse_scheme(struct uri_parser *parser, struct aws_byte_cursor *str) {
     const uint8_t *location_of_colon = memchr(str->ptr, ':', str->len);