name_resolution.h

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// uvco (c) 2023 Lewin Bormann. See LICENSE for specific terms.
 
#pragma once
 
#include <cstddef>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <uv.h>
 
#include "uvco/internal/internal_utils.h"
#include "uvco/promise/promise.h"
#include "uvco/run.h"
 
#include <coroutine>
#include <cstdint>
#include <optional>
#include <span>
#include <string>
#include <string_view>
#include <variant>
 
namespace uvco {
 
 
class AddressHandle {
  struct NtopHelper_;
 
public:
  constexpr static size_t ipv4Length = 4;
  constexpr static size_t ipv6Length = 16;
 
  AddressHandle() = default;
  AddressHandle(const AddressHandle &) = default;
  AddressHandle(AddressHandle &&) = default;
  AddressHandle &operator=(const AddressHandle &) = default;
  AddressHandle &operator=(AddressHandle &&) = default;
  ~AddressHandle() = default;
 
  AddressHandle(std::span<const uint8_t> ipv4_or_6, uint16_t port,
                uint32_t v6scope = 0);
  AddressHandle(uint32_t ipv4, uint16_t port);
  AddressHandle(std::string_view ip, uint16_t port, uint32_t v6scope = 0);
  explicit AddressHandle(const struct addrinfo *ai);
  explicit AddressHandle(const struct sockaddr *sa);
 
  // The address, formatted by `inet_ntop(3)`.
  [[nodiscard]] std::string address() const {
    return std::visit(NtopHelper_{}, addr_);
  }
  [[nodiscard]] uint16_t port() const;
  int family() const;
  [[nodiscard]] const struct sockaddr *sockaddr() const;
 
  [[nodiscard]] std::string toString() const;
 
private:
  std::variant<struct sockaddr_in, struct sockaddr_in6> addr_;
 
  struct NtopHelper_ {
    static std::string operator()(const struct sockaddr_in &ipv4);
    static std::string operator()(const struct sockaddr_in6 &ipv6);
    static std::string ntop(int family, void *addr);
  };
};
 
class Resolver {
  struct AddrinfoAwaiter_;
 
public:
  explicit Resolver(const Loop &loop) : loop_{&loop} {}
 
  Promise<AddressHandle> gai(std::string_view host, std::string_view port,
                             int af_hint = AF_UNSPEC);
  Promise<AddressHandle> gai(std::string_view host, uint16_t port,
                             int af_hint = AF_UNSPEC);
 
private:
  const Loop *loop_;
 
  static void onAddrinfo(uv_getaddrinfo_t *req, uv_status status,
                         struct addrinfo *result);
 
  struct AddrinfoAwaiter_ {
    AddrinfoAwaiter_() : req_{} {}
    [[nodiscard]] bool await_ready() const { return false; }
    bool await_suspend(std::coroutine_handle<> handle);
 
    struct addrinfo *await_resume();
 
    uv_getaddrinfo_t req_;
    std::optional<struct addrinfo *> addrinfo_;
    std::optional<int> status_;
    std::optional<std::coroutine_handle<>> handle_;
  };
};
 
 
} // namespace uvco