UDP Socket Programming - recvfrom() one Port and sendto() other Port - c

Question

UDP Socket Programming - Server listening on Port 5000 - Client listening on Port 6000
recvfrom() from one Port - 5000
sendto() to other Port - 6000 to the same client.
Server.c
#include <stdio.h> /* for printf() and fprintf() */
#include <sys/socket.h> /* for socket() and bind() */
#include <arpa/inet.h> /* for sockaddr_in and inet_ntoa() */
#include <stdlib.h> /* for atoi() */
#include <string.h> /* for memset() */
#include <unistd.h> /* for close() */
#define MAXSIZE 255 /* Longest string */
#define SRC_PORT 5000
#define DST_PORT 6000
int main(int argc, char *argv[])
{
int sock; /* Socket */
struct sockaddr_in ServAddr; /* Local address */
struct sockaddr_in ClntAddr; /* Client address */
socklen_t CliAddrLen; /* Length of incoming message */
char recBuffer[MAXSIZE]; /* Buffer for echo string */
int recvMsgSize; /* Size of received message */
int i;
/* Create socket for sending/receiving datagrams */
if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
DieWithError("socket() failed");
/* Construct local address structure */
memset(&ServAddr, 0, sizeof(ServAddr)); /* Zero out structure */
ServAddr.sin_family = AF_INET; /* Internet address family */
ServAddr.sin_addr.s_addr = htonl(INADDR_ANY); /* Any incoming interface */
ServAddr.sin_port = htons(SRC_PORT); /* Local port */
/* Construct address structure */
memset(&ClntAddr, 0, sizeof(ClntAddr)); /* Zero out structure */
ClntAddr.sin_family = AF_INET; /* Internet address family */
ClntAddr.sin_addr.s_addr = inet_addr("192.168.1.*");
ClntAddr.sin_port = htons(DST_PORT);
/* Bind to the local address */
if (bind(sock, (struct sockaddr *) &ServAddr, sizeof(ServAddr)) < 0)
DieWithError("bind() failed");
for (;;) /* Run forever */
{
printf("Listening on UDP:5000 \n");
/* Set the size of the in-out parameter */
cliAddrLen = sizeof(ClntAddr);
/* Block until receive message from a client */
if ((recvMsgSize = recvfrom(sock, recBuffer, MAXSIZE, 0,(struct sockaddr *) &ClntAddr, &cliAddrLen)) < 0)
DieWithError("recvfrom() failed") ;
printf("Handling Client: %s\n", inet_ntoa(ClntAddr.sin_addr));
printf("Received Data: %s",recBuffer);
printf("\n");
/* Send response datagram back to the client */
if (sendto(sock, recBuffer, MAXSIZE, 0, (struct sockaddr *) & ClntAddr, sizeof(ClntAddr)) < 0)
DieWithError("sendto() failed");
}
/* NOT REACHED */
}
It works perfectly. Client and Server programming using different ports for sending and receiving the data.
Thank you
Regards

Answer 1

this is wrong
lntAddr.sin_addr.s_addr = inet_addr("CLIENT_IP");
inet_addr takes a dotted ip address not a host name