websever in C by skynet

webserver.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define BUFFER_SIZE 1024
#define NUM_THREADS 5

// Structure for passing arguments to the thread function
typedef struct {
    int client_fd;
    struct sockaddr_in client_addr;
} thread_arg_t;

// The thread function that handles a client request
void* handle_request(void* arg) {
    thread_arg_t* thread_arg = (thread_arg_t*)arg;
    int client_fd = thread_arg->client_fd;
    struct sockaddr_in client_addr = thread_arg->client_addr;
    free(arg);

    char buffer[BUFFER_SIZE];
    int bytes_received = recv(client_fd, buffer, BUFFER_SIZE, 0);
    if (bytes_received < 0) {
        perror("recv");
        return NULL;
    }
    printf("Received %d bytes from %s:%d\n", bytes_received, inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

    // Send a simple response to the client
    const char* response = "HTTP/1.1 200 OK\nContent-Type: text/plain\nContent-Length: 12\n\nHello, World!\n";
    send(client_fd, response, strlen(response), 0);

    close(client_fd);
    return NULL;
}

int main(int argc, char** argv) {
    if (argc < 2) {
        fprintf(stderr, "Usage: %s [port]\n", argv[0]);
        return 1;
    }

    // Create the server socket
    int server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd < 0) {
        perror("socket");
        return 1;
    }

    // Bind the socket to the specified port
    int port = atoi(argv[1]);
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(port);
    if (bind(server_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) {
        perror("bind");
        return 1;
    }

    // Listen for incoming connections
    if (listen(server_fd, 5) < 0)
    {
      perror("listen");
      return 1;
    }
  
  printf("Listening on port %d\n", port);

  // Create a pool of threads to handle client requests
  pthread_t threads[NUM_THREADS];
  for (int i = 0; i < NUM_THREADS; i++) {
      if (pthread_create(&threads[i], NULL, handle_request, NULL) != 0) {
          perror("pthread_create");
          return 1;
      }
  }

  // Accept client connections and dispatch them to the threads
  while (1) {
      struct sockaddr_in client_addr;
      socklen_t client_addr_len = sizeof(client_addr);
      int client_fd = accept(server_fd, (struct sockaddr*)&client_addr, &client_addr_len);
      if (client_fd < 0) {
          perror("accept");
          return 1;
      }

      // Find an available thread to handle the request
      int i;
      for (i = 0; i < NUM_THREADS; i++) {
          if (pthread_tryjoin_np(threads[i], NULL) == 0) {
              break;
          }
      }

      // If no threads are available, close the connection
      if (i == NUM_THREADS) {
          printf("No threads available, closing connection\n");
          close(client_fd);
          continue;
      }

      // Pass the client connection to the thread
      thread_arg_t* thread_arg = (thread_arg_t*)malloc(sizeof(thread_arg_t));
      thread_arg->client_fd = client_fd;
      thread_arg->client_addr = client_addr;
      if (pthread_create(&threads[i], NULL, handle_request, thread_arg) != 0) {
          perror("pthread_create");
          return 1;
      }
  }

  return 0;
}

/*
This code creates a fixed pool of threads, and each time a new connection is accepted it tries to find an available thread to handle the request. If no threads are available, the connection is closed.

I hope this helps! Let me know if you have any questions or need further clarification.
*/