Added grpc_uri_get_query_arg per comments.

src/core/lib/client_config/uri_parser.c

@@ -281,6 +281,18 @@ grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors) {
   return uri;
 }
 
+const char *grpc_uri_get_query_arg(const grpc_uri *uri, const char *key) {
+  GPR_ASSERT(key != NULL);
+  if (key[0] == '\0') return NULL;
+
+  for (size_t i = 0; i < uri->num_query_parts; ++i) {
+    if (0 == strcmp(key, uri->query_parts[i])) {
+      return uri->query_parts_values[i];
+    }
+  }
+  return NULL;
+}
+
 void grpc_uri_destroy(grpc_uri *uri) {
   if (!uri) return;
   gpr_free(uri->scheme);

src/core/lib/client_config/uri_parser.h

@@ -53,6 +53,10 @@ typedef struct {
 /** parse a uri, return NULL on failure */
 grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors);
 
+/** return the part of a query string after the '=' in "?key=xxx&...", or NULL
+ * if key is not present */
+const char *grpc_uri_get_query_arg(const grpc_uri *uri, const char *key);
+
 /** destroy a uri */
 void grpc_uri_destroy(grpc_uri *uri);
 

test/core/client_config/uri_parser_test.c

@@ -80,6 +80,11 @@ static void test_query_parts() {
     GPR_ASSERT(0 == strcmp("", uri->query_parts[3]));
     GPR_ASSERT(NULL == uri->query_parts_values[3]);
 
+    GPR_ASSERT(NULL == grpc_uri_get_query_arg(uri, "a"));
+    GPR_ASSERT(0 == strcmp("B", grpc_uri_get_query_arg(uri, "b")));
+    GPR_ASSERT(0 == strcmp("", grpc_uri_get_query_arg(uri, "c")));
+    GPR_ASSERT(NULL == grpc_uri_get_query_arg(uri, ""));
+
     GPR_ASSERT(0 == strcmp("frag", uri->fragment));
     grpc_uri_destroy(uri);
   }