feat: GrpcSource for ETL ng (#1745)

For #1596 and #1597

src/web/Resolver.cpp

@@ -19,10 +19,15 @@
 
 #include "web/Resolver.hpp"
 
-#include <boost/asio/ip/address.hpp>
+#include "util/Assert.hpp"
 
+#include <boost/asio/ip/address.hpp>
+#include <boost/asio/ip/tcp.hpp>
+
+#include <sstream>
 #include <string>
 #include <string_view>
+#include <utility>
 #include <vector>
 
 namespace asio = boost::asio;
@@ -50,19 +55,51 @@ isAddress(std::string_view hostname)
     return ec == boost::system::errc::success;
 }
 
+std::string
+toString(auto const& endpoint)
+{
+    std::stringstream ss;
+    ss << endpoint;
+    return ss.str();
+}
+
 }  // namespace
 
 std::vector<std::string>
 Resolver::resolve(std::string_view hostname, std::string_view service)
 {
-    if (isAddress(hostname)) {
-        return {std::string(hostname)};
-    }
+    ASSERT(not service.empty(), "Service is unspecified. Use `resolve(hostname)` instead.");
+
+    if (isAddress(hostname))
+        return {std::string(hostname) + ':' + std::string(service)};
 
     std::vector<std::string> endpoints;
-    for (auto const& endpoint : resolver_.resolve(hostname, service)) {
-        endpoints.push_back(endpoint.endpoint().address().to_string());
-    }
+    for (auto const& endpoint : doResolve(hostname, service))
+        endpoints.push_back(toString(endpoint));
+
+    return endpoints;
+}
+
+std::vector<std::string>
+Resolver::resolve(std::string_view hostname)
+{
+    if (isAddress(hostname))
+        return {std::string(hostname)};
+
+    std::vector<std::string> endpoints;
+    for (auto const& endpoint : doResolve(hostname, ""))
+        endpoints.push_back(endpoint.address().to_string());
+
+    return endpoints;
+}
+
+std::vector<boost::asio::ip::tcp::endpoint>
+Resolver::doResolve(std::string_view hostname, std::string_view service)
+{
+    std::vector<boost::asio::ip::tcp::endpoint> endpoints;
+    for (auto&& endpoint : resolver_.resolve(hostname, service))
+        endpoints.push_back(std::move(endpoint));
+
     return endpoints;
 }