Write an HTTP request in C++.

Can you write an HTTP server in C++ without any framework?#

Without using any high-level frameworks, you can implement a simple HTTP request using the C++ standard library and some system calls. Below is a basic example that demonstrates how to create a simple HTTP client using header files like <iostream> and <sys/socket.h> from the C++ standard library to send requests to a server and receive responses.

Example: Simple HTTP Client#

This example will use raw socket programming to send an HTTP GET request and print the server's response.

#include <iostream>
#include <string>
#include <cstring>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>

int main() {
    // Server address and port
    const char* server = "example.com";
    const int port = 80;

    // Create socket
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        std::cerr << "Error creating socket" << std::endl;
        return 1;
    }

    // Server address structure
    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(port);

    // Resolve server address
    struct hostent* server_info = gethostbyname(server);
    if (server_info == nullptr) {
        std::cerr << "Error, no such host" << std::endl;
        return 1;
    }

    // Copy server IP address to serv_addr structure
    memcpy(&serv_addr.sin_addr.s_addr, server_info->h_addr, server_info->h_length);

    // Connect to server
    if (connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
        std::cerr << "Error connecting to server" << std::endl;
        return 1;
    }

    // Send HTTP GET request
    const char* request = "GET / HTTP/1.1\r\nHost: example.com\r\nConnection: close\r\n\r\n";
    if (send(sockfd, request, strlen(request), 0) < 0) {
        std::cerr << "Error sending request" << std::endl;
        return 1;
    }

    // Receive server response
    char buffer[4096];
    int bytes_received = 0;
    while ((bytes_received = recv(sockfd, buffer, sizeof(buffer) - 1, 0)) > 0) {
        buffer[bytes_received] = '\0';
        std::cout << buffer;
    }

    if (bytes_received < 0) {
        std::cerr << "Error receiving response" << std::endl;
        return 1;
    }

    // Close socket
    close(sockfd);

    return 0;
}

Code Explanation#

Create Socket:
- Use the socket function to create a TCP socket.
Server Address Structure:
- Use the sockaddr_in structure to store the server's address information.
- Use the gethostbyname function to resolve the server's domain name.
Connect to Server:
- Use the connect function to connect to the server.
Send HTTP Request:
- Construct a simple HTTP GET request string and use the send function to send the request.
Receive Server Response:
- Use the recv function to receive the server's response and print it to standard output.
Close Socket:
- Use the close function to close the socket.

Compilation and Running#

Save the above code as http_client.cpp, then compile and run using g++:

g++ -o http_client http_client.cpp
./http_client

Notes#

This example is for demonstration purposes only; actual applications may need to handle more edge cases, such as timeouts, error handling, etc.
To simplify the example, the separation of HTTP response headers and body is not handled here; actual applications may require more complex parsing logic.