Changing UDP communication from local machine to remote machine.
Hi,
I'm hoping someone can help me. My brain feels fried from trying to figure this out.
I have two programs, client.c and server.c that will connect via UDP. The sever sends a code and the client receives it. All on a local machine. I would like to move the client to a remote machine and achieve the same functionality.
server.c
Code:
// Declare includes.
#include <arpa/inet.h>
#include <errno.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <termios.h>
#include <unistd.h>
// Declare defines.
#define PORT_1 50036
#define PORT_2 50037
#define PORT_3 50038
#define PORT_NAME_SIZE 6
// Declare defines.
#define PROGRAM_NAME_SIZE 50
// Declare stuctures.
typedef struct _ports
{
int fd;
char name[PORT_NAME_SIZE + 1];
struct sockaddr_in serveraddr;
} PORTS;
// Declare global variables.
char program_name[PROGRAM_NAME_SIZE + 1] = {0};
// Declare function prototypes.
void open_port (PORTS *port, int port_num);
PORTS * open_ports (void);
void run_announcer (PORTS *ports);
void start_process (void);
int main (int argc, char *argv[])
{
// Get program name for error reporting.
strcpy(program_name, basename(argv[0]));
// Check number of arguments.
if(argc != 1)
{
fprintf(stderr, "Usage: %s\n", program_name);
exit(EXIT_FAILURE);
}
// Start the process.
start_process();
// Exit cleanly.
exit(EXIT_SUCCESS);
}
void start_process (void)
{
// Declare variables.
PORTS *ports = NULL;
// Open the outgoing ports.
ports = open_ports();
// Run announcer.
run_announcer(ports);
// Close all the sockets.
close(ports[0].fd);
close(ports[1].fd);
close(ports[2].fd);
}
PORTS * open_ports (void)
{
// Delcare variables.
static PORTS ports[3] = {0};
// Name all ports first.
strcpy(ports[0].name, "PORT_1");
strcpy(ports[1].name, "PORT_2");
strcpy(ports[2].name, "PORT_3");
// Open UDP port.
open_port(&(ports[0]), PORT_1);
// Open UDP port.
open_port(&(ports[1]), PORT_2);
// Open UDP port.
open_port(&(ports[2]), PORT_3);
// Return the ports array.
return(ports);
}
void open_port (PORTS *port, int port_num)
{
// Delcare variables.
// Open socket for UDP operation.
if((port->fd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
fprintf(stderr, "%s: open_port error: socket failed (%s)\n", program_name, strerror(errno));
exit(EXIT_FAILURE);
}
// Clear variables.
memset(&port->serveraddr, 0, sizeof(port->serveraddr));
// Load server variables.
port->serveraddr.sin_family = AF_INET;
port->serveraddr.sin_port = htons(port_num);
// Set to loopback address '127.0.0.1'.
// port->serveraddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
port->serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
}
void run_announcer (PORTS *ports)
{
// Delcare variables.
char code[2] = {0, 0};
// Loop forever.
while((code[0] = getch()))
{
// Send out message.
if(sendto(ports[0].fd, code, 1, 0, (struct sockaddr *) &ports[0].serveraddr, sizeof(ports[0].serveraddr)) == -1)
{
fprintf(stderr, "%s: run_announcer error: sendto failed (%s) (%s)\n", program_name, strerror(errno), ports->name);
exit(EXIT_FAILURE);
}
if(sendto(ports[1].fd, code, 1, 0, (struct sockaddr *) &ports[1].serveraddr, sizeof(ports[1].serveraddr)) == -1)
{
fprintf(stderr, "%s: run_announcer error: sendto failed (%s) (%s)\n", program_name, strerror(errno), ports->name);
exit(EXIT_FAILURE);
}
if(sendto(ports[2].fd, code, 1, 0, (struct sockaddr *) &ports[2].serveraddr, sizeof(ports[2].serveraddr)) == -1)
{
fprintf(stderr, "%s: run_announcer error: sendto failed (%s) (%s)\n", program_name, strerror(errno), ports->name);
exit(EXIT_FAILURE);
}
printf("message sent\n");
}
}
int getch (void)
{
// Declare variables.
int c = {0};
struct termios oldt = {0};
struct termios newt = {0};
// Get terminal attributes.
tcgetattr(STDIN_FILENO, &oldt);
// Store attributes.
newt = oldt;
// Set terminal to non-buffered.
newt.c_lflag &= ~(ICANON | ECHO);
tcsetattr(STDIN_FILENO, TCSANOW, &newt);
// Get user input.
c = getchar();
// Reset terminal attributes.
tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
// Return character.
return(c);
}
client.c
Code:
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#define PORT 50037
int main( void )
{
// Declare variables.
int i = {0};
int fd = {0};
int length = {0};
char buffer[200] = {0};
struct sockaddr_in serveraddr = {0};
if((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
perror("socket failed");
return 1;
}
memset(&serveraddr, 0, sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(PORT);
// serveraddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
serveraddr.sin_addr.s_addr = inet_addr("192.168.1.103");
if(bind(fd, (struct sockaddr *) &serveraddr, sizeof(serveraddr)) < 0)
{
perror( "bind failed" );
return 1;
}
while(1)
{
length = recvfrom(fd, buffer, sizeof(buffer) - 1, 0, NULL, 0);
if(length < 0)
{
perror("recvfrom failed");
break;
}
buffer[length] = '\0';
printf("%d bytes: '%s'\n", length, buffer);
}
// Close the socket.
close(fd);
}
I get an error on the client of `bind failed: Cannot assign requested address`.
What am I missing? I belive I'm using the correct struct. Can someone please help?
Ty,
Yonut
