Hello everyone,
This is my first program in C and I have ran into weird issue. I am implementing a simple server & client program in C.
From my main() in client I call a send_message() function which I believe binds with server and sends the message to the server side.
The function proto type for send_message is: int send_message(int Port_num, char*input)
where Port_num is for port number to connect to and
input: is a user input.
For a test I tried printing the user input as such send_message(3100,"HELLO"). This prints Hello in the send_message function
BUT, if I instead get a user input and try pass it to the function, I do not get an output.
This is how I am passing the user input
char id;
scanf("%d",&id);
send_message(3100, &id);
I have pasted my complete code here as well. Thank you for any input.
server.c
#include <stdio.h>
#include <netdb.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include "functions.h"
#define STR_SIZE 4000
int PORT;
void* server_thread_func(void *arg)
{
const int Size = 64;
int Array[Size];
char buf[STR_SIZE];
unsigned int addr_len;
char serverport[STR_SIZE];
char input[10];
int id =0;
int rv, val, sockfd, totbytes;
struct sockaddr_in their_addr;
struct addrinfo hints, *servinfo, *p;
val = 1;
sprintf(serverport, "%d", PORT);
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_PASSIVE;
if ((rv = getaddrinfo(NULL, serverport, &hints, &servinfo)) != 0)
{
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return (NULL);
}
for (p = servinfo; p != NULL; p = p->ai_next)
{
if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1)
{
perror("server: socket");
continue;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(int)) == -1)
{
perror("setsockopt");
exit(1);
}
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1)
{
close(sockfd);
perror("server: bind");
continue;
}
break;
}
if (p == NULL)
{
fprintf(stderr, "server: failed to bind\n");
return (NULL);
}
freeaddrinfo(servinfo);
printf("server: listening for connections...\n");
while (1)
{
if((totbytes = recvfrom(sockfd, buf, STR_SIZE-1, 0, (struct sockaddr *)&their_addr, &addr_len)) == -1)
{
continue;
}
printf("Response from %s\n", inet_ntoa(their_addr.sin_addr));
printf("Size of message is %d bytes\n", totbytes);
//buf[totbytes] = '\0';
if(strcmp(buf,"readlock"))
{
/** printf("Enter an index value: \n");
scanf("%d",&id);
//sprintf("Index: %d",&id);
printf("yes \n");
get_lock(id);**/
}
//printf("1 \n");
printf( buf);
}
close(sockfd);
}
int main(int argc, char** argv)
{
if (argc != 2)
{
fprintf(stderr, "Usage: %s port\n", argv[0]);
return 1;
}
PORT = atoi(argv[1]);
pthread_t server_thread_id;
pthread_create(&server_thread_id, NULL, server_thread_func, NULL);
if (pthread_join(server_thread_id, NULL))
{
printf("error joining thread");
abort();
}
return 0;
}
client.c
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include "functions.h"
#define STR_SIZE 5000
int read_message(int sockfd)
{
int totbytes;
char buf[STR_SIZE];
unsigned int addr_len;
struct sockaddr_in their_addr;
if((totbytes = recvfrom(sockfd, buf, STR_SIZE-1, 0, (struct sockaddr *)&their_addr, &addr_len)) == -1)
{
perror("recvfrom");
exit(1);
}
printf("Response from %s\n", inet_ntoa(their_addr.sin_addr));
printf("Message is %d bytes\n", totbytes);
buf[totbytes] = '\0';
printf("Message: %s\n", buf);
return (totbytes);
}
int send_message(int c_port, char *buf)
{
int sockfd, totbytes;
struct sockaddr_in their_addr;
if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
perror("server: socket");
exit(1);
}
their_addr.sin_family = AF_INET;
their_addr.sin_port = htons(c_port);
their_addr.sin_addr.s_addr = INADDR_ANY;
memset(&(their_addr.sin_zero), '\0', 8);
if((totbytes = sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&their_addr, sizeof(struct sockaddr))) == -1)
{
perror("sendto");
exit(1);
}
printf("SendMessage: %s",buf);
printf("sent %d bytes to %s\n", totbytes, inet_ntoa(their_addr.sin_addr));
close(sockfd);
return (totbytes);
}
int main()
{
char id = 0;
printf("Enter the client id between 1 and 64 \n");
scanf("%d",&id);
//char *n =
send_message(3100, &id);
return 0;
}
Please note that this is not completely my own code. I have been testing codes from online tutorials.
