UDP Sockets in C - Sendto() Send failed : invalid arguments - c

Question

I am trying to implement UDP sockets in C in a very simple/basic fashion. My programs are meant to send/receive files between terminals with one program running on each. I am having a problem with the sendto() function in my client code. Here is my code:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include <errno.h>
#define BUFFER_SIZE 512
int main(int argc, char *argv[])
{
struct sockaddr_in client;
int sockfd, bytes, errno, slen = sizeof(client);
char buffer[BUFFER_SIZE];
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if(sockfd == -1)
{
perror("Socket creation failed.");
return 0;
}
client.sin_addr.s_addr = INADDR_ANY;
client.sin_family = AF_INET;
client.sin_port = htons( 0 );
if( bind(sockfd, (struct sockaddr *)&client, sizeof(client)) == -1)
{
perror("Bind call failed.");
return 0;
}
while(1)
{
printf("Enter message : ");
fgets(buffer, BUFFER_SIZE, stdin);
printf("Message: %s\n", buffer);
bytes = sendto(sockfd, buffer, strlen(buffer), 0, (struct sockaddr *)&client, sizeof(client));
printf("Bytes: %d\n", bytes);
if(bytes == -1)
{
printf("Error number: %d", errno);
perror("Send failed.");
return 0;
}
memset(buffer,'\0', BUFFER_SIZE);
if( recvfrom(sockfd, buffer, BUFFER_SIZE, 0, (struct sockaddr *)&client, &slen) == -1)
{
perror("Recieve failed.");
return 0;
}
puts(buffer);
}
close(sockfd);
return 0;
}
No matter what I enter into the buffer, I always get error number 22 from sendto() for invalid arguments. I have tried every solution or tweak I have come across but nothing seems to work.

Answer 1

Just add this piece of code after bind()
getsockname(sockfd, (struct sockaddr *)&client, &slen);
man page
DESCRIPTION
The getsockname() function returns the current address for the specified
socket.
The address_len parameter should be initialized to indicate the amount of
space pointed to by address. On return it contains the actual size of
the address returned (in bytes).
The address is truncated if the buffer provided is too small.
RETURN VALUES
The getsockname() function returns the value 0 if successful; otherwise
the value -1 is returned and the global variable errno is set to indicate
the error.