UDP Server not receiving in Unix (Cygwin) - unix

Question

So I've looked around and noticed some others having a similar problem to mine. However I have yet to find a solution. I've created a client and server in Unix (Cygwin) using UDP. When I try to use sendto() in order to send a message to the server from the client, the server doesn't seem to be receiving the the packet. I've done error checking and it seems like the client isn't having a problem sending the packet, yet still the server cannot receive it correctly. The server just seems to be dead for the most part. I'm using my machine to host the client and the server and I'm attempting to connect to the server on my home address (127.0.0.1) and a random port. Any suggestions at this point would be much appreciated.
Server Code:
#include <stdio.h> /* standard C i/o facilities */
#include <stdlib.h> /* needed for atoi() / atof() */
#include <unistd.h> /* Unix System Calls */
#include <sys/types.h> /* system data type definitions */
#include <sys/socket.h> /* socket specific definitions */
#include <netinet/in.h> /* INET constants and stuff */
#include <arpa/inet.h> /* IP address conversion stuff */
#include <string.h> /* String manipulation */
#include <time.h> /* Used to to measure process execution time */
/* Server main routine - this is an iterative server
1. create a socket
2. bind the socket and print out the port number assigned
3. do forever
get next connection
handle the connection
enddo
*/
int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in servaddr, cliaddr;
int n;
//Create UDP socket
if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror("Problem creating socket\n");
exit(1);
}
//Setup the UDP server
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(0);
//Bind the UDP to the socket
if (bind(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr))<0)
{
perror("Error bind\n");
exit(1);
}
//Print the port for the UDP server
int length = sizeof( servaddr );
if (getsockname(sockfd, (struct sockaddr *) &servaddr, &length) < 0)
{
perror("Error getsockname\n");
exit(1);
}
printf("The Server passive socket port number is %d\n",ntohs(servaddr.sin_port));
//Send/Recv from client
char msg[100];
for(;;)
{
socklen_t len = sizeof(cliaddr);
if( recvfrom(sockfd, msg, 100, 0, (struct sockaddr*) &cliaddr, &len) < 0)
{
perror("Error on recv\n");
exit(1);
}
printf("Msg: %s\n", msg);
//read(sockfd, msg, 10);
//sendto(sockfd, msg, n, 0, (struct sockaddr*) &cliaddr, len);
}
close(sockfd);
return 0;
}
Client Code:
#include <stdio.h> /* standard C i/o facilities */
#include <stdlib.h> /* needed for atoi() */
#include <unistd.h> /* Unix System Calls */
#include <sys/types.h> /* system data type definitions */
#include <sys/socket.h> /* socket specific definitions */
#include <netinet/in.h> /* INET constants and stuff */
#include <arpa/inet.h> /* IP address conversion stuff */
#include <string.h>
/* client program:
The following must passed in on the command line:
name of the server (argv[1])
port number of the server (argv[2])
*/
int main( int argc, char **argv )
{
int sockfd;
struct sockaddr_in servaddr;
int n;
//Ensure we have full args
if (argc != 3)
{
printf("Usage: client <server name> <server port>\n");
exit(1);
}
//Setup the port number
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(atoi(argv[2]));
//Setup the client IP
//inet_pton(AF_INET, argv[1], &servaddr.sin_addr)) <= 0
if( inet_aton(argv[1], &servaddr.sin_addr) == 0)
{
perror("Error with server IP\n");
exit(1);
}
//Create socket
if( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
perror("Error on socket\n");
exit(1);
}
/*if (connect(sockfd,(struct sockaddr *) &servaddr, sizeof(servaddr)) < 0 )
{
printf("Problem connecting socket\n");
exit(1);
}*/
//Send msg
char msg[10] = "123456789";
for(;;)
{
socklen_t len = sizeof(servaddr);
if( (sendto(sockfd, msg, strlen(msg), 0, (struct sockaddr*) &servaddr, len)) < 0 )
{
perror("Error on sendto():\n");
exit(1);
}
//write(sockfd, msg, strlen(msg));
//n = recvfrom(sockfd, msg2, 10, 0, NULL, NULL);
//printf("Msg: %s\n", msg2);
}
close(sockfd);
return 0;
}

Answer 1

First, your sender just sends data as fast as it possibly can, whether or not anyone or anything is listening. That's not a good thing to do.
Second, your receiver passes msg through to a %s printf specifier. But %s is only for C-style strings, and msg is not a C-style string (nothing puts a zero byte on the end of it). You also throw the return value of recvfrom away, so you can't convert it into a string because you have no idea how many of its bytes are valid.
Third, your server is creating a SOCK_STREAM socket!