1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <string.h>
4. #include <unistd.h>
5. #include <arpa/inet.h>
6. #include <pthread.h>
7.  
8. #define PORT 12345
9. #define BUFFER_SIZE 1024
10. #define MAX_CLIENTS 5
11.  
12. // Structure to hold client information
13. struct ClientInfo {
14.     int socket;
15.     struct sockaddr_in address;
16. };
17.  
18. // Function to handle each client
19. void *handleClient(void *arg) {
20.     struct ClientInfo *clientInfo = (struct ClientInfo *)arg;
21.     int clientSocket = clientInfo->socket;
22.  
23.     // Open and send file
24.     FILE *fileToSend = fopen&#40;"file_to_send.txt", "rb"&#41;;
25.     if (!fileToSend) {
26.         perror("Error opening file");
27.         close(clientSocket);
28.         free(clientInfo);
29.         pthread_exit(NULL);
30.     }
31.  
32.     char buffer[BUFFER_SIZE];
33.  
34.     while (1) {
35.         int bytesRead = fread(buffer, 1, sizeof(buffer), fileToSend);
36.         if (bytesRead <= 0) {
37.             break; // End of file or error
38.         }
39.         send(clientSocket, buffer, bytesRead, 0);
40.     }
41.  
42.     printf("File sent to %s:%dn", inet_ntoa(clientInfo->address.sin_addr), ntohs(clientInfo->address.sin_port));
43.  
44.     // Close the socket and file
45.     fclose(fileToSend);
46.     close(clientSocket);
47.     free(clientInfo);
48.     pthread_exit(NULL);
49. }
50.  
51. int main() {
52.     int serverSocket, clientSocket;
53.     struct sockaddr_in serverAddr, clientAddr;
54.     socklen_t addrSize = sizeof(struct sockaddr_in);
55.  
56.     // Create socket
57.     if ((serverSocket = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
58.         perror("Error creating socket");
59.         exit(EXIT_FAILURE);
60.     }
61.  
62.     // Configure server address
63.     memset(&serverAddr;, 0, sizeof(serverAddr));
64.     serverAddr.sin_family = AF_INET;
65.     serverAddr.sin_port = htons(PORT);
66.     serverAddr.sin_addr.s_addr = INADDR_ANY;
67.  
68.     // Bind the socket
69.     if (bind(serverSocket, (struct sockaddr *)&serverAddr;, sizeof(serverAddr)) == -1) {
70.         perror("Error binding socket");
71.         close(serverSocket);
72.         exit(EXIT_FAILURE);
73.     }
74.  
75.     // Listen for incoming connections
76.     if (listen(serverSocket, MAX_CLIENTS) == -1) {
77.         perror("Error listening for connections");
78.         close(serverSocket);
79.         exit(EXIT_FAILURE);
80.     }
81.  
82.     printf("Server listening on port %d...n", PORT);
83.  
84.     // Array to store thread IDs
85.     pthread_t threadIDs[MAX_CLIENTS];
86.     int clientCount = 0;
87.  
88.     while (1) {
89.         // Accept a connection
90.         if ((clientSocket = accept(serverSocket, (struct sockaddr *)&clientAddr;, &addrSize;)) == -1) {
91.             perror("Error accepting connection");
92.             close(serverSocket);
93.             exit(EXIT_FAILURE);
94.         }
95.  
96.         // Create a new thread to handle the client
97.         struct ClientInfo *clientInfo = (struct ClientInfo *)malloc(sizeof(struct ClientInfo));
98.         clientInfo->socket = clientSocket;
99.         clientInfo->address = clientAddr;
100.  
101.         if (pthread_create(&threadIDs;[clientCount], NULL, handleClient, (void *)clientInfo) != 0) {
102.             perror("Error creating thread");
103.             close(clientSocket);
104.             free(clientInfo);
105.         }
106.  
107.         clientCount++;
108.  
109.         // Check if the maximum number of clients is reached
110.         if (clientCount >= MAX_CLIENTS) {
111.             printf("Maximum number of clients reached. Closing the server.n");
112.             break;
113.         }
114.     }
115.  
116.     // Join all threads before exiting
117.     for (int i = 0; i < clientCount; i++) {
118.         pthread_join(threadIDs[i], NULL);
119.     }
120.  
121.     // Close the server socket
122.     close(serverSocket);
123.  
124.     return 0;
125. }
126.