improved UDP

Author: apsrcreatix

04-udp-echo-client-server/README.md

@@ -24,4 +24,26 @@ unused nonreservedport for its communication.
 ## Who would use an echo service '?'
 
 It is not a service that the average user finds interesting. However, programmers who design, implement, measure, or modify network protocol software, or network managers who test routes and debug communication problems, often use echo servers in testing. For example, an echo service can be used
-to determineif it is possible to reach a remote machine.
+to determineif it is possible to reach a remote machine.
+
+## Learn about code
+
+* For implementation of UDP use SOCK_DGRAM
+
+```C
+ int serverDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
+```
+
+* For sending message use sendto function
+
+```C
+ sendto(serverDescriptor,sendMessage,MAXLINE,0,(struct sockaddr*)&serverAddress,addressLength);
+```
+
+* For recieving message use recv
+
+```C
+ recvfrom(socketDescriptor,message,MAXLINE,0,(struct sockaddr*)&clientAddress,&addressLength);
+```
+
+* On server side only use ```bind()``` function

04-udp-echo-client-server/client.c

@@ -7,37 +7,43 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 
 #define MAXLINE 1024
+#define PORT 5035
 
 int main(){
- int socket_descriptor;
- int n;
- socklen_t length;
- char sendline[MAXLINE],recvline[MAXLINE];
- struct sockaddr_in servaddr;
+ // socket descriptor creation in udp mode
+ int serverDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
+ 
+ // for storing address of address
+ socklen_t addressLength;
+ 
+ // preparing message 
+ char sendMessage[MAXLINE],recvMessage[MAXLINE];
  printf("\nEnter message :");
- scanf("%s",sendline);
- socket_descriptor = socket(AF_INET,SOCK_DGRAM,0);
-
- servaddr.sin_family = AF_INET;
- servaddr.sin_addr.s_addr = INADDR_ANY;
- servaddr.sin_port = htons(5035);
-
-int isConnect = connect(socket_descriptor,(struct sockaddr*)&servaddr,sizeof(servaddr));
-
-if(isConnect==-1){
- printf("\nNot connected");
-}
-
- length = sizeof(servaddr);
- sendto(socket_descriptor,sendline,MAXLINE,0,(struct sockaddr*)&servaddr,length);
- n=recvfrom(socket_descriptor,recvline,MAXLINE,0,NULL,NULL);
- recvline[n]=0;
- printf("\nServer's Echo : %s\n",recvline);
+ fgets(sendMessage,sizeof(sendMessage),stdin);
+ 
+ // storing address in serverAddress
+ struct sockaddr_in serverAddress;
+ serverAddress.sin_family = AF_INET;
+ serverAddress.sin_addr.s_addr = INADDR_ANY;
+ serverAddress.sin_port = htons(PORT);
+ 
+ // storing address size 
+ addressLength = sizeof(serverAddress);
+
+ // checking connection
+ connect(serverDescriptor,(struct sockaddr*)&serverAddress,addressLength);
+ 
+ // sending and receiving the messages 
+ sendto(serverDescriptor,sendMessage,MAXLINE,0,(struct sockaddr*)&serverAddress,addressLength);
+ recvfrom(serverDescriptor,recvMessage,MAXLINE,0,NULL,NULL);
+ 
+ printf("\nServer's Echo : %s\n",recvMessage);
 
  return 0;
 }

04-udp-echo-client-server/server.c

@@ -13,36 +13,36 @@
 // time
 
 #define MAXLINE 1024
+#define PORT 5035
 
 int main(){
 
- int socket_descriptor;
- int n;
- socklen_t length;
- char msg[MAXLINE];
- struct sockaddr_in servaddr,cliaddr;
+ int socketDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
+ int number;
+ socklen_t addressLength;
+ char message[MAXLINE];
 
- socket_descriptor = socket(AF_INET,SOCK_DGRAM,0);
+ struct sockaddr_in serverAddress,clientAddress;
+ serverAddress.sin_family = AF_INET;
+ serverAddress.sin_addr.s_addr=INADDR_ANY;
+ serverAddress.sin_port=htons(PORT);
 
- servaddr.sin_family = AF_INET;
- servaddr.sin_addr.s_addr=INADDR_ANY;
- servaddr.sin_port=htons(5035);
+ bind(socketDescriptor,(struct sockaddr*)&serverAddress,sizeof(serverAddress));
 
- bind(socket_descriptor,(struct sockaddr*)&servaddr,sizeof(servaddr));
+ printf("\nServer Started ...\n");
 
- printf("\nServer Started ...");
-while(1){
+ while(1){
  printf("\n");
- length = sizeof(cliaddr);
+ addressLength = sizeof(clientAddress);
 
- n = recvfrom(socket_descriptor,msg,MAXLINE,0,(struct sockaddr*)&cliaddr,&length);
+ number = recvfrom(socketDescriptor,message,MAXLINE,0,(struct sockaddr*)&clientAddress,&addressLength);
 
- printf("\n Client's Message:%s ",msg);
+ printf("\n Client's Message: %s ",message);
 
- if(n<6)
+ if(number<6)
  perror("send error");
 
- sendto(socket_descriptor,msg,n,0,(struct sockaddr*)&cliaddr,length);
+ sendto(socketDescriptor,message,number,0,(struct sockaddr*)&clientAddress,addressLength);
  }
  return 0;
 }