C - UDP Client not completing SendTo to Echo Server - c

Question

I'm trying to complete a simple echo server. The goal is to repeat back the message to the client. The server and client both compile. The server runs, you just need to give it a port to run on. The client has the address, the port, and the message. When the client goes through the program to the sendto section, it stop and waits there. My goal it to have it sent to the server, and the server to send it back.
I believe that the server works, or it least is in the mode to receive as it enters the while loops to do that. That part can send notes back that it works.
For the client, I've tried sending the argument directly, but also through a c-string. I've tried one hard coded in, and none of them have worked. I've been at it for many hours, so I decided to ask for help because I can't think of anything else as a newbie.
Client
//argv[1] address, argv[2] port, argv[3] message
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
int main(int argc, char *argv[]){
int BUF_LEN;
for (BUF_LEN = 0; argv[3][BUF_LEN] != '\0'; BUF_LEN++){
// printf("BUF_LEN = %i\n", BUF_LEN);
}
int s, n, port_no, r;
struct sockaddr_in server_addr;
char *haddr, *message;
char buf[BUF_LEN+1];
printf("Variables created\n");
s = socket(AF_INET, SOCK_DGRAM, 0); // create a socket for UDP
printf("Socket created as s: %i\n", s);
bzero((char *)&server_addr, sizeof(server_addr)); // clear
server_addr.sin_family = AF_INET; //IPv4 Internet family
server_addr.sin_addr.s_addr = inet_addr(argv[1]); //server address
server_addr.sin_port = htons(atoi(argv[2])); // server port number
printf("Server addr complete\n");
//Bind() - Not necessary
printf("Bind skipped\n");
//sendto()
r = sendto(s, argv[3], strlen(argv[3]), 0, (struct sockaddr *)&server_addr, BUF_LEN);
printf("Message Sent");
//recvfrom()
n = recvfrom (s, buf, BUF_LEN, 0, (struct sockaddr *)&server_addr, &BUF_LEN);
printf("Message Received: %s\n", buf);
close(s);
}
Server
//Argv[1] : port number
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
int main(int argc, char *argv[]){
int n;
int MAXLINE = 512;
int sock_server, sock_client, r, len;
char buf[MAXLINE];
struct sockaddr_in my_addr, client_addr;
//printf("Variables created\n");
sock_server = socket (PF_INET, SOCK_DGRAM, 0);
//printf("Socket created\n");
if (sock_server < 0){
perror("Bind failed");
exit(1);
}
bzero(&my_addr, sizeof(my_addr)); // clear
my_addr.sin_family = AF_INET; //Address Family INET
my_addr.sin_port = htons(atoi(argv[1])); //Server port number
my_addr.sin_addr.s_addr = htonl(INADDR_ANY); // Accept from anywhere
//printf("Addresses created\n");
r = bind(sock_server, (struct sockaddr*)(&my_addr), sizeof(my_addr));
if (r < 0) {
perror("Bind failed");
exit(1);
}
printf("Read to receive\n");
while(1) {
//printf("First while loop\n");
len = sizeof(struct sockaddr_in);
//recvfrom()
n = recvfrom (sock_client, buf, MAXLINE, 0, (struct sockaddr *)&client_addr, &len);
while (n > 1){
printf("Second while loop\n");
printf("Message Received: %s\n", buf);
//sendto()
sendto(sock_client, buf, n, 0, (struct sockaddr *)&client_addr, len);
n = 0;
}
}
close(sock_client); //close the client socket
//printf("Connection sock_client Closed");
}

Answer 1

Here is the fixed version of the client using sizeof(server_addr) in the client call of sendto:
//argv[1] address, argv[2] port, argv[3] message
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
int main(int argc, char *argv[]){
int BUF_LEN;
for (BUF_LEN = 0; argv[3][BUF_LEN] != '\0'; BUF_LEN++){
// printf("BUF_LEN = %i\n", BUF_LEN);
}
int s, n, port_no, r;
struct sockaddr_in server_addr;
char *haddr, *message;
char buf[BUF_LEN+1];
printf("Variables created\n");
s = socket(AF_INET, SOCK_DGRAM, 0); // create a socket for UDP
printf("Socket created as s: %i\n", s);
bzero((char *)&server_addr, sizeof(server_addr)); // clear
server_addr.sin_family = AF_INET; //IPv4 Internet family
server_addr.sin_addr.s_addr = inet_addr(argv[1]); //server address
server_addr.sin_port = htons(atoi(argv[2])); // server port number
printf("Server addr complete\n");
//Bind() - Not necessary
printf("Bind skipped\n");
r = sendto(s, argv[3], strlen(argv[3]), 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
printf("Message Sent");
n = recvfrom (s, buf, BUF_LEN, 0, (struct sockaddr *)&server_addr, &BUF_LEN);
printf("Message Received: %s\n", buf);
close(s);
}