UDP server added

computer_networks/lab/lab1/UDPserver.c

@@ -0,0 +1,69 @@
+/**
+ * /mnt/z/my_git/sixth-semester/computer_networks/lab/lab1/UDPserver.c
+ * @author Avinal Kumar
+ * @since January 27, 2021
+ * Roll Number - 185067
+ *
+ * LAB 1 
+*/
+
+// Server side implementation of UDP client-server model
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#define PORT 2047    // Q1: previously 8080
+#define MAXLINE 4096 // Q4: changed to 4096
+
+// Driver code
+int main()
+{
+    int sockfd;
+    char buffer[MAXLINE];
+    char *hello = "UDP Server: Yeah we've got the new message.";
+    struct sockaddr_in servaddr, cliaddr;
+
+    // Creating socket file descriptor
+    if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
+    {
+        perror("socket creation failed");
+        exit(EXIT_FAILURE);
+    }
+
+    memset(&servaddr, 0, sizeof(servaddr));
+    memset(&cliaddr, 0, sizeof(cliaddr));
+
+    // Filling server information
+    servaddr.sin_family = AF_INET;                     // IPv4
+    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1"); // Q3: changed to loacalhost
+    servaddr.sin_port = htons(PORT);
+
+    // Bind the socket with the server address
+    if (bind(sockfd, (const struct sockaddr *)&servaddr,
+             sizeof(servaddr)) < 0)
+    {
+        perror("bind failed");
+        exit(EXIT_FAILURE);
+    }
+
+    int len, n;
+    n = recvfrom(sockfd, (char *)buffer, MAXLINE,
+                 MSG_WAITALL, (struct sockaddr *)&cliaddr,
+                 &len);
+    buffer[n] = '\0';
+    printf("Client : %s\n", buffer);
+    printf("Processing ...!!!\n");
+    sleep(4);
+
+    sendto(sockfd, (const char *)hello, strlen(hello),
+           MSG_CONFIRM, (const struct sockaddr *)&cliaddr,
+           len);
+    printf("New message sent.\n");
+
+    return 0;
+}