04_intro_to_sockets: Add UDP functionailty

04_intro_to_sockets/README.md

@@ -7,5 +7,14 @@ a LED, a button and a temperature sensor.
 
 ```bash
 $ make
-$ ./sockets
+```
+
+## Testing with nc
+
+Clients:
+```bash
+# TCP
+$ nc -l 1234
+# UDP
+$ nc -ul 1234
 ```

04_intro_to_sockets/lib/sockets.c

@@ -11,8 +11,9 @@
 
 static void error_handling(char *message, int sock) {
     perror(message);
+    if (sock != -1)
+        close(sock);
     close(sock);
-    exit(1);
 }
 
 int tcp_create_socket() {
@@ -111,3 +112,82 @@ void process_request(int clnt_sock) {
     write(clnt_sock, message, strlen(message));
 }
 
+int udp_create_socket() {
+    int sock = socket(PF_INET, SOCK_DGRAM, 0);
+    if (sock == -1) {
+        error_handling("UDP socket creation failed", sock);
+    }
+    return sock;
+}
+
+void udp_bind_socket(int sock, int port) {
+    struct sockaddr_in serv_addr;
+    memset(&serv_addr, 0, sizeof(serv_addr));
+    serv_addr.sin_family = AF_INET;
+    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+    serv_addr.sin_port = htons(port);
+
+    if (bind(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) == -1) {
+        error_handling("UDP bind failed", sock);
+    }
+}
+
+void udp_send_message(int sock, char *server_ip, int port, char *message) {
+    struct sockaddr_in dest_addr;
+    memset(&dest_addr, 0, sizeof(dest_addr));
+    dest_addr.sin_family = AF_INET;
+    dest_addr.sin_addr.s_addr = inet_addr(server_ip);
+    dest_addr.sin_port = htons(port);
+
+    sendto(sock, message, strlen(message), 0,
+           (struct sockaddr *)&dest_addr, sizeof(dest_addr));
+}
+
+char *udp_receive_message(int sock) {
+    struct sockaddr_in from_addr;
+    socklen_t from_addr_size = sizeof(from_addr);
+    char *buffer = malloc(BUFFER_SIZE);
+    if (buffer == NULL) {
+        error_handling("Failed to allocate memory for buffer", sock);
+    }
+
+    int str_len = recvfrom(sock, buffer, BUFFER_SIZE, 0,
+                           (struct sockaddr *)&from_addr, &from_addr_size);
+    if (str_len == -1) {
+        free(buffer);
+        error_handling("recvfrom() failed", sock);
+    }
+
+    buffer[str_len] = '\0';  // Null-terminate the string
+    return buffer;
+}
+
+void handle_udp_client(int serv_sock) {
+    struct sockaddr_in clnt_addr;
+    socklen_t clnt_addr_size = sizeof(clnt_addr);
+    char buffer[BUFFER_SIZE];
+
+    while (1) {
+        int str_len = recvfrom(serv_sock, buffer, BUFFER_SIZE - 1, 0,
+                               (struct sockaddr*)&clnt_addr, &clnt_addr_size);
+        if (str_len == -1)
+            error_handling("recvfrom() failed", serv_sock);
+
+        buffer[str_len] = '\0';  // Null-terminate the string
+
+        time_t t = time(NULL);
+        struct tm *timeinfo;
+
+        if (strcmp(buffer, "1") == 0) {
+            timeinfo = localtime(&t); // Local time
+        } else {
+            timeinfo = gmtime(&t);    // GMT time
+        }
+
+        strftime(buffer, BUFFER_SIZE, "%Y-%m-%d %H:%M:%S", timeinfo);
+
+        // Prepare a response - could be customized based on the message
+        sendto(serv_sock, buffer, strlen(buffer), 0,
+               (struct sockaddr*)&clnt_addr, clnt_addr_size);
+    }
+}

04_intro_to_sockets/lib/sockets.h

@@ -19,4 +19,15 @@ int tcp_accept(int serv_sock);
 // Function to process a client request
 void process_request(int clnt_sock);
 
+
+int udp_create_socket();
+
+void udp_send_message(int sock, char *server_ip, int port, char *message);
+
+void udp_bind_socket(int sock, int port);
+
+char* udp_receive_message(int sock);
+
+void handle_udp_client(int serv_sock);
+
 #endif // SOCKETS_LIB_H

04_intro_to_sockets/src/daytimeUDPCli.c

@@ -0,0 +1,19 @@
+#include <stdio.h> // For printf()
+#include <unistd.h> // For close()
+#include <stdlib.h> // For exit(), atoi()
+#include "sockets.h"
+
+int main(int argc, char *argv[]) {
+    if (argc != 4) {
+        printf("Usage : %s <IP> <port> <message_to_send>\n", argv[0]);
+        exit(1);
+    }
+
+    int sock = udp_create_socket();
+    udp_send_message(sock, argv[1], atoi(argv[2]), argv[3]);
+    char *response = udp_receive_message(sock);
+    printf("Received from server: %s\n", response);
+    free(response);
+    close(sock);
+    return 0;
+}

04_intro_to_sockets/src/daytimeUDPSrv.c

@@ -0,0 +1,16 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "sockets.h"
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        printf("Usage: %s <port>\n", argv[0]);
+        exit(1);
+    }
+
+    int sock = udp_create_socket();
+    udp_bind_socket(sock, atoi(argv[1]));
+    handle_udp_client(sock);
+    return 0;
+}