TCP/IP-——C++编程详解
1. TCP/IP 编程基本概念
- TCP（传输控制协议）：面向连接、可靠的传输层协议，保证数据顺序和完整性。
- IP（网际协议）：负责将数据包路由到目标地址。
- Socket（套接字）：网络通信的端点，通过IP和端口标识。
2. 服务器端实现步骤
步骤 1：创建套接字
#include 步骤 2：绑定套接字到地址和端口
// 设置地址结构
struct sockaddr_in address;
address.sin_family = AF_INET; // IPv4
address.sin_addr.s_addr = INADDR_ANY; // 绑定所有接口
address.sin_port = htons(8080); // 端口号（需转为网络字节序）
// 绑定套接字
if (bind(server_fd, (struct sockaddr*)&address, sizeof(address)) < 0) {
std::cerr << "Bind failed\n";
return -1;
}
步骤 3：监听连接请求
// 监听，队列长度设为5
if (listen(server_fd, 5) < 0) {
std::cerr << "Listen failed\n";
return -1;
}
std::cout << "Server listening on port 8080...\n";
步骤 4：接受客户端连接
// 接受连接
int addrlen = sizeof(address);
int new_socket = accept(server_fd, (struct sockaddr*)&address, (socklen_t*)&addrlen);
if (new_socket < 0) {
std::cerr << "Accept failed\n";
return -1;
}
std::cout << "Client connected\n";
步骤 5：接收和发送数据
// 接收数据
char buffer[1024] = {0};
int valread = read(new_socket, buffer, 1024);
std::cout << "Received: " << buffer << std::endl;
// 发送响应
const char* response = "Hello from server";
send(new_socket, response, strlen(response), 0);
std::cout << "Response sent\n";
步骤 6：关闭套接字
close(new_socket);
close(server_fd);
return 0;
}
3. 客户端实现步骤
步骤 1：创建套接字
#include 步骤 2：设置服务器地址
struct sockaddr_in serv_addr;
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(8080); // 服务器端口
// 将IP地址从字符串转为二进制格式
if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
std::cerr << "Invalid address\n";
return -1;
}
步骤 3：连接到服务器
if (connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
std::cerr << "Connection failed\n";
return -1;
}
std::cout << "Connected to server\n";
步骤 4：发送和接收数据
// 发送数据
const char* message = "Hello from client";
send(sock, message, strlen(message), 0);
std::cout << "Message sent\n";
// 接收响应
char buffer[1024] = {0};
int valread = read(sock, buffer, 1024);
std::cout << "Server response: " << buffer << std::endl;
步骤 5：关闭套接字
close(sock);
return 0;
}
4. 关键函数和结构体
socket(): 创建套接字。bind(): 绑定套接字到地址和端口。listen(): 进入监听状态。accept(): 接受客户端连接。connect(): 客户端连接到服务器。send()/recv()或write()/read(): 发送和接收数据。sockaddr_in: 存储地址信息的结构体（IPv4）。
5. 注意事项
- 错误处理：每次调用网络函数后检查返回值。
- 字节序转换：
htons(): 主机字节序转网络字节序（端口）。inet_pton(): 字符串IP转二进制。
- 资源释放：使用
close()关闭套接字。 - 端口复用：通过
setsockopt()设置SO_REUSEADDR选项。
6. 完整示例代码
-
服务器端
#include#include #include #include #include int main() { int server_fd, new_socket; struct sockaddr_in address; int addrlen = sizeof(address); char buffer[1024] = {0}; const char* hello = "Hello from server"; // 创建socket if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) { perror("socket failed"); exit(EXIT_FAILURE); } // 绑定socket address.sin_family = AF_INET; address.sin_addr.s_addr = INADDR_ANY; address.sin_port = htons(8080); if (bind(server_fd, (struct sockaddr*)&address, sizeof(address)) < 0) { perror("bind failed"); exit(EXIT_FAILURE); } // 监听socket if (listen(server_fd, 3) < 0) { perror("listen"); exit(EXIT_FAILURE); } // 接受连接 if ((new_socket = accept(server_fd, (struct sockaddr*)&address, (socklen_t*)&addrlen)) < 0) { perror("accept"); exit(EXIT_FAILURE); } // 读取客户端发送的数据 read(new_socket, buffer, 1024); std::cout << "Message from client: " << buffer << std::endl; // 向客户端发送数据 send(new_socket, hello, strlen(hello), 0); std::cout << "Hello message sent\n"; // 关闭socket close(new_socket); close(server_fd); return 0; } #include #include #include #include #include int main() { int server_fd, new_socket; struct sockaddr_in address; int addrlen = sizeof(address); char buffer[1024] = {0}; const char* hello = "Hello from server"; // 创建socket if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) { perror("socket failed"); exit(EXIT_FAILURE); } // 绑定socket address.sin_family = AF_INET; address.sin_addr.s_addr = INADDR_ANY; address.sin_port = htons(8080); if (bind(server_fd, (struct sockaddr*)&address, sizeof(address)) < 0) { perror("bind failed"); exit(EXIT_FAILURE); } // 监听socket if (listen(server_fd, 3) < 0) { perror("listen"); exit(EXIT_FAILURE); } // 接受连接 if ((new_socket = accept(server_fd, (struct sockaddr*)&address, (socklen_t*)&addrlen)) < 0) { perror("accept"); exit(EXIT_FAILURE); } // 读取客户端发送的数据 read(new_socket, buffer, 1024); std::cout << "Message from client: " << buffer << std::endl; // 向客户端发送数据 send(new_socket, hello, strlen(hello), 0); std::cout << "Hello message sent\n"; // 关闭socket close(new_socket); close(server_fd); return 0; } -
客户端：
#include#include #include #include #include int main() { int sock = 0; struct sockaddr_in serv_addr; char buffer[1024] = {0}; const char* hello = "Hello from client"; // 创建socket if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) { std::cerr << "Socket creation error" << std::endl; return -1; } // 设置服务器地址 serv_addr.sin_family = AF_INET; serv_addr.sin_port = htons(8080); // 将IP地址从字符串转换为网络格式 if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) { std::cerr << "Invalid address/Address not supported" << std::endl; return -1; } // 连接到服务器 if (connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) { std::cerr << "Connection Failed" << std::endl; return -1; } // 向服务器发送数据 send(sock, hello, strlen(hello), 0); std::cout << "Hello message sent" << std::endl; // 读取服务器发送的数据 read(sock, buffer, 1024); std::cout << "Message from server: " << buffer << std::endl; // 关闭socket close(sock); return 0; }
编译运行：
# 编译服务器
g++ server.cpp -o server
# 编译客户端
g++ client.cpp -o client
# 启动服务器
./server
# 启动客户端（另起终端）
./client
对于更复杂的场景（如多客户端并发），需结合多线程或异步I/O（如 select/epoll）进行扩展。