Socket send from server failing, error: Socket operation on non-socket - c

Question

I have below functions written for a server side socket implementation -
void SetUpServerSocket()
{
/* Setting up Server socket*/
struct sockaddr_in srv_addr;
int yes=1;
/* Open datagram socket */
if((bind_my_socket = socket(AF_INET,SOCK_STREAM,0)) < 0)
{
print_log("Bind socket failed");
return ;
}
bzero((char*) &srv_addr,sizeof(srv_addr));
srv_addr.sin_family = AF_INET;
srv_addr.sin_addr.s_addr = inet_addr(my_ip);
srv_addr.sin_port = htons(my_port);
if(setsockopt(bind_my_socket,SOL_SOCKET,SO_REUSEPORT,&yes,sizeof(yes))!=0)
{
print_log("Can't set socket options'SO_REUSEPORT'");
return;
}
if(bind(bind_my_socket,(struct sockaddr*) &srv_addr,sizeof(srv_addr)) < 0)
{
print_log("Bind failed");
return ;
}
if (listen (bind_my_socket,1024) < 0)
{
print_log("Cannot listen on socket\n");
return;
}
}
void* AcceptMsgConnFromClient()
{
/*This will accept connection from client*/
struct sockaddr_in client_addr;
int client_addr_len, r;
my_socket=0;
client_addr_len=sizeof(client_addr);
r=accept(bind_my_socket,(struct sockaddr *)&client_addr,&client_addr_len);
my_socket=r;
return NULL;
}
void* ReceiveClientMsg()
{
/* This will accept messages from client */
u_char buf[2000];
struct sockaddr_in client_addr;
int client_addr_len;
int len;
pthread_t thread;
int connfd;
u_char* pCmd[100];
AcceptMsgConnFromClient();
//Working here
/*if(my_socket>0){
if(send(my_socket, "Server Hello", strlen("Server Hello"), 0) < 0)
{
print_log("Send data failed\n");
print_log(strerror(errno));
print_log("\n");
}
}*/
memset(buf,0,2000);
for(;;)
{
len=recvfrom(my_socket,buf,2000,0,(struct sockaddr *)&client_addr,&client_addr_len);
if(len<=0)
{
AcceptMsgConnFromClient();
continue;
}
//my logic to handle buffer
} // ;; for
usleep(1000);
close(bind_my_socket);
return NULL;
}
void SendMsgtoClient()
{
if(send(my_socket, "Server Hello to Client", strlen("Server Hello to Client"), 0) < 0)
{
print_log("Send data to client failed\n");
print_log(strerror(errno));
print_log("\n");
return;
}
}
From main(in different file) I've called 'SetUpServerSocket()' once and 'ReceiveClientMsg()' in a thread(required to keep processing the buffer).
From a different function I'm calling 'SendMsgtoClient()' whenever I want to send something to Client. However, this fails with error as 'Socket operation on non-socket'.
But when I send something on same my_socket from ReceiveClientMsg thread, it works, and not when I do it from another function. I tried and printed value of my_socket in SendMsgtoClient(), it has an integer which is same as what is being assigned from AcceptMsgConnFromClient().
I have declared the socket variables used as-
static int bind_my_socket = 0, my_socket = 0;
Any help would be appreciated, thank you!

Answer 1

You're not printing the correct error message. The first call to print_log() is likely to change errno, so you're printing that error message, not the error from send(). Save errno in another variable.
void SendMsgtoClient()
{
if(send(my_socket, "Server Hello to Client", strlen("Server Hello to Client"), 0) < 0)
{
int saved_errno = errno;
print_log("Send data to client failed\n");
print_log(strerror(saved_errno));
print_log("\n");
return;
}
}