HPUX 11.31 IA64 Non-blocking socket connection failing

[Jithin Prakash]

Hi,

I have written a client c program which connects to a server socket on the specified port. I have compiled the program using gcc. If I am marking my socket as non-blocking, the connection fails. If I comment out the code which makes my socket non-blocking, the connection succeeds.

Here is my client code:

#include
#include
#include
#include
#include
#include
#include

int main(int argc, char *argv[])
{
int sockfd, portno, n;
struct sockaddr_in serv_addr;
struct hostent *server;

char buffer[256];
if (argc < 3) {
fprintf(stderr,"usage %s hostname port\n", argv[0]);
exit(0);
}
portno = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
printf("ERROR opening socket");
/* Code to mark the socket as non-blocking */
int flags;
flags = fcntl(sockfd, F_GETFL, 0);
fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);

server = gethostbyname(argv[1]);
if (server == NULL) {
fprintf(stderr,"ERROR, no such host\n");
exit(0);
}
bzero((char *) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char *)server->h_addr,
(char *)&serv_addr.sin_addr.s_addr,
server->h_length);
serv_addr.sin_port = htons(portno);
if (connect( sockfd, &serv_addr, sizeof(serv_addr)) < 0)
{
printf("ERROR connecting!!");
}

printf("Please enter the message: ");
bzero(buffer,256);
fgets(buffer,255,stdin);
n = write(sockfd,buffer,strlen(buffer));
if (n < 0)
printf("ERROR writing to socket");
bzero(buffer,256);
n = read(sockfd,buffer,255);
if (n < 0)
printf("ERROR reading from socket");
printf("%s\n",buffer);
return 0;
}

Is this a TCP layer issue? How can I get non-blocking sockets to connect successfully?

Thanks a lot,
Jithin

[Jithin Prakash]

Hi,

I found out that connect() on a non-blocking socket will basically always return EINPROGRESS immediately. We have to do select() to establish connection.

A useful thread:
http://www.developerweb.net/forum/showthread.php?t=3196

Thanks