Add simple TCP CLient

Author: urbytes21

src/socket/CMakeLists.txt

@@ -3,6 +3,8 @@ set(SOCKET_SOURCES
     # Socket
     ${CMAKE_CURRENT_SOURCE_DIR}/simple_tcp/TCPServer.cpp
     ${CMAKE_CURRENT_SOURCE_DIR}/simple_tcp/SimpleTCPServer.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/simple_tcp/TCPClient.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/simple_tcp/SimpleTCPClient.cpp
 )
 
 set(SOCKET_SOURCES ${SOCKET_SOURCES} PARENT_SCOPE)

src/socket/simple_tcp/SimpleTCPClient.cpp

@@ -0,0 +1,41 @@
+#include <iostream>
+#include "ExampleRegistry.h"
+#include "TCPClient.h"
+
+namespace {
+
+void run() {
+  try {
+    TCPClient client("127.0.0.1", 8080);
+
+    if (!client.connect()) {
+      std::cout << "connect failed\n";
+      return;
+    }
+
+    client.send("Hello server\n");
+
+    std::string response = client.receive();
+
+    std::cout << "server: " << response << std::endl;
+
+    client.close();
+  } catch (const std::exception& e) {
+    std::cout << "error: " << e.what() << std::endl;
+  }
+}
+
+}  // namespace
+
+class SimpleTCPClient : public IExample {
+ public:
+  std::string group() const override { return "socket/tcp"; }
+
+  std::string name() const override { return "SimpleTCPClient"; }
+
+  std::string description() const override { return "Simple TCP Client"; }
+
+  void execute() override { run(); }
+};
+
+REGISTER_EXAMPLE(SimpleTCPClient, "socket/tcp", "SimpleTCPClient");

src/socket/simple_tcp/TCPClient.cpp

@@ -0,0 +1,77 @@
+#include "TCPClient.h"
+
+#include <sys/socket.h>
+#include <stdexcept>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <unistd.h>
+
+TCPClient::TCPClient(const std::string& host, uint16_t port)
+    : host_{host}, port_{port}, client_fd_{-1} {}
+
+bool TCPClient::connect() {
+  client_fd_ = socket(AF_INET, SOCK_STREAM, 0);
+  if (client_fd_ < 0) {
+    throw std::runtime_error("socket failed.");
+  }
+
+  // specifying the address
+  sockaddr_in serverAddress{};
+  serverAddress.sin_family = AF_INET;
+  serverAddress.sin_port = htons(port_);
+
+  // serverAddress.sin_addr.s_addr = INADDR_ANY;
+  if (::inet_pton(AF_INET, host_.c_str(), &serverAddress.sin_addr) <= 0) {
+    throw std::runtime_error("invalid address");
+  }
+
+  // sending connection request
+  return (
+      ::connect(client_fd_,
+                reinterpret_cast<sockaddr*>(&serverAddress),  // global syscall
+                sizeof(serverAddress)) == 0);
+}
+
+void TCPClient::send(const std::string& msg) {
+  if (client_fd_ < 0) {
+    throw std::runtime_error("socket not connected");
+  }
+
+  const char* data = msg.c_str();
+  size_t total = 0;
+  size_t len = msg.size();
+  while (total < len) {
+    ssize_t sent = ::send(client_fd_, data + total, len - total, 0);
+    if (sent <= 0) {
+      throw std::runtime_error("send failed");
+    }
+    total += sent;
+  }
+}
+
+std::string TCPClient::receive() {
+  if (client_fd_ < 0) {
+    throw std::runtime_error("socket not connected");
+  }
+
+  char buffer[1024];
+
+  ssize_t bytes = recv(client_fd_, buffer, sizeof(buffer), 0);
+  if (bytes < 0) {
+    throw std::runtime_error("recv failed");
+  }
+
+  if (bytes == 0) {
+    throw std::runtime_error("connection closed");
+  }
+
+  return std::string(buffer, bytes);
+}
+
+void TCPClient::close() {
+  if (client_fd_ >= 0) {
+    ::close(client_fd_);
+    client_fd_ = -1;
+  }
+}

src/socket/simple_tcp/TCPClient.h

@@ -0,0 +1,18 @@
+#pragma once
+#include <stdint.h>
+#include <string>
+
+class TCPClient {
+ public:
+  TCPClient(const std::string& host, uint16_t port);
+
+  bool connect();
+  void close();
+  void send(const std::string& msg);
+  std::string receive();
+
+ private:
+  std::string host_;
+  uint16_t port_;
+  int client_fd_;
+};