tcp_client.h
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// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
#pragma once
#ifdef _WIN32
#error include tcp_client-windows.h instead
#endif
// tcp client helper
#include <spdlog/common.h>
#include <spdlog/details/os.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>
#include <netinet/tcp.h>
#include <string>
namespace spdlog {
namespace details {
class tcp_client
{
int socket_ = -1;
public:
bool is_connected() const
{
return socket_ != -1;
}
void close()
{
if (is_connected())
{
::close(socket_);
socket_ = -1;
}
}
int fd() const
{
return socket_;
}
~tcp_client()
{
close();
}
// try to connect or throw on failure
void connect(const std::string &host, int port)
{
close();
struct addrinfo hints
{};
memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_INET; // IPv4
hints.ai_socktype = SOCK_STREAM; // TCP
hints.ai_flags = AI_NUMERICSERV; // port passed as as numeric value
hints.ai_protocol = 0;
auto port_str = std::to_string(port);
struct addrinfo *addrinfo_result;
auto rv = ::getaddrinfo(host.c_str(), port_str.c_str(), &hints, &addrinfo_result);
if (rv != 0)
{
auto msg = fmt::format("::getaddrinfo failed: {}", gai_strerror(rv));
throw_spdlog_ex(msg);
}
// Try each address until we successfully connect(2).
int last_errno = 0;
for (auto *rp = addrinfo_result; rp != nullptr; rp = rp->ai_next)
{
#if defined(SOCK_CLOEXEC)
const int flags = SOCK_CLOEXEC;
#else
const int flags = 0;
#endif
socket_ = ::socket(rp->ai_family, rp->ai_socktype | flags, rp->ai_protocol);
if (socket_ == -1)
{
last_errno = errno;
continue;
}
rv = ::connect(socket_, rp->ai_addr, rp->ai_addrlen);
if (rv == 0)
{
break;
}
last_errno = errno;
::close(socket_);
socket_ = -1;
}
::freeaddrinfo(addrinfo_result);
if (socket_ == -1)
{
throw_spdlog_ex("::connect failed", last_errno);
}
// set TCP_NODELAY
int enable_flag = 1;
::setsockopt(socket_, IPPROTO_TCP, TCP_NODELAY, (char *)&enable_flag, sizeof(enable_flag));
// prevent sigpipe on systems where MSG_NOSIGNAL is not available
#if defined(SO_NOSIGPIPE) && !defined(MSG_NOSIGNAL)
::setsockopt(socket_, SOL_SOCKET, SO_NOSIGPIPE, (char *)&enable_flag, sizeof(enable_flag));
#endif
#if !defined(SO_NOSIGPIPE) && !defined(MSG_NOSIGNAL)
#error "tcp_sink would raise SIGPIPE since niether SO_NOSIGPIPE nor MSG_NOSIGNAL are available"
#endif
}
// Send exactly n_bytes of the given data.
// On error close the connection and throw.
void send(const char *data, size_t n_bytes)
{
size_t bytes_sent = 0;
while (bytes_sent < n_bytes)
{
#if defined(MSG_NOSIGNAL)
const int send_flags = MSG_NOSIGNAL;
#else
const int send_flags = 0;
#endif
auto write_result = ::send(socket_, data + bytes_sent, n_bytes - bytes_sent, send_flags);
if (write_result < 0)
{
close();
throw_spdlog_ex("write(2) failed", errno);
}
if (write_result == 0) // (probably should not happen but in any case..)
{
break;
}
bytes_sent += static_cast<size_t>(write_result);
}
}
};
} // namespace details
} // namespace spdlog