add nng error code.

Nng/ErrorCode.cpp

@@ -0,0 +1,22 @@
+#include "ErrorCode.h"
+#include <nng/nng.h>
+
+namespace Nng {
+const char *ErrorCategory::name() const noexcept {
+    return "nng";
+}
+
+std::string ErrorCategory::message(int ev) const {
+    return nng_strerror(ev);
+}
+
+static const std::error_category &errorCategory() {
+    static ErrorCategory instance;
+    return instance;
+}
+
+std::error_code makeErrorCode(int code) {
+    return {code, errorCategory()};
+}
+
+} // namespace Nng

Nng/ErrorCode.h

@@ -0,0 +1,16 @@
+#ifndef __ERRORCODE_H__
+#define __ERRORCODE_H__
+
+#include <system_error>
+
+namespace Nng {
+class ErrorCategory : public std::error_category {
+public:
+    const char *name() const noexcept final;
+    std::string message(int ev) const final;
+};
+
+std::error_code makeErrorCode(int code);
+} // namespace Nng
+
+#endif // __ERRORCODE_H__

Nng/Option.h

@@ -0,0 +1,18 @@
+#ifndef __OPTION_H__
+#define __OPTION_H__
+
+#include <chrono>
+#include <nng/nng.h>
+
+namespace Nng {
+
+template <typename T>
+struct Option {
+    constexpr Option(const char *opt) : option(opt) {};
+    const char *option;
+};
+
+inline constexpr Option<std::chrono::milliseconds> RecvTimeout(NNG_OPT_RECVTIMEO);
+} // namespace Nng
+
+#endif // __OPTION_H__

Nng/Socket.h

@@ -2,6 +2,8 @@
 #define __SOCKET_H__
 
 #include "Buffer.h"
+#include "ErrorCode.h"
+#include "Option.h"
 #include "Protocol.h"
 #include <cassert>
 #include <nng/nng.h>
@@ -22,8 +24,11 @@ public:
         nng_listen(m_socket, url.data(), nullptr, flags);
     }
 
-    void dial(const std::string_view &url, int flags = 0) {
-        nng_dial(m_socket, url.data(), nullptr, flags);
+    void dial(const std::string_view &url, std::error_code &error, int flags = 0) {
+        int status = nng_dial(m_socket, url.data(), nullptr, flags);
+        if (status != 0) {
+            error = makeErrorCode(status);
+        }
     }
 
     void send(const void *data, size_t size, int flags = 0) {
@@ -37,6 +42,11 @@ public:
         return Buffer(data, size);
     }
 
+    template <class T>
+    void setOption(const Option<T> &opt, const T &value) {
+        nng_socket_set_ms(m_socket, opt.option, value.count());
+    }
+
 protected:
     nng_socket m_socket = NNG_SOCKET_INITIALIZER;
 };