[SOLVED] "resource temporarily unavailable" in recv in socket programming

mrjmrj · 02-12-2013, 08:01 AM

I want to read and write over Wanpipe driver (a network device driver for Sangoma cards) via socket programming but i get this message error: "resource temporarily unavailable". The card is working and i see it send and receive packets in ifconfig. I have included my code and would be very pleased if somebody help me in this.
A related question: I set the socket to blocking mode but the recv message does not block? how could i block the recv?

Code:

int main(void)
{
int sd;
int buflen=WP_HEADER + MAX_PACKET;
char buf[buflen];
struct wan_sockaddr_ll sa;
sd = socket(AF_WANPIPE, SOCK_RAW,0);
if (sd < 0) /* if socket failed to initialize, exit */
{
perror("Error Creating Socket");
exit(1);
}
printf("Socket Descriptor:%d\n",sd);
memset(&sa,0,sizeof(struct wan_sockaddr_ll));

strncpy((char*)sa.sll_card,"wanpipe1",sizeof(sa.sl l_card));
strncpy((char*)sa.sll_device,"w1g1",sizeof(sa.sll_ device));	
sa.sll_protocol = htons(PVC_PROT);
sa.sll_family = AF_WANPIPE;

if(bind(sd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
{
perror("error bind failed");
close(sd);
exit(1);
}


int data=0;
int ret=ioctl(sd,FIONBIO,&data);
if (ret < 0) {
perror("ioctl error!");
close(sd);
return 1;
}

fd_set read_fds;
struct timeval timeout;
timeout.tv_sec = 10;
timeout.tv_usec = 0;
FD_ZERO(&read_fds);
FD_SET(sd,&read_fds);
if(select(sd+1, &read_fds, NULL, NULL, &timeout) < 0)
{
perror("select() error!");
exit(1);
}

if (FD_ISSET(sd,&read_fds))
printf("There is data for reading\n");
else
printf("There is no data for reading\n");

// MSG_WAITALL | MSG_PEEK | MSG_OOB
int r=recv(sd,buf,buflen,0);
if (r < 0) {
perror("Wanpipe raw socket reading");
close(sd);
exit(1);
}
printf("\nNumber of bytes read into the buffer: %d",r);
printf("\nThe read buffer: ");
puts(buf);
close(sd);
}

thank you in advance.

JohnGraham · 02-12-2013, 11:00 AM

First of all, please place all code in code tags.

Second, is your select() timing out? You appear to be recv()ing whether or not you've seen FD_ISSET().

mrjmrj · 02-12-2013, 12:57 PM

select() is timing out and the else message ("There is no data for reading\n") is in the output. then for recv i have "resource temporarily unavailable". if i put recv under [if (FD_ISSET(sd,&read_fds))] it is not called. In other words both select() and recv() indicate that there is no data! but as I said my card is receiving and sending. ifconfig shows there are transmitted and received packets. I do not know the problem is because of my code (select or recv) or from the card.

JohnGraham · 02-12-2013, 05:40 PM

First, I don't know anything about the AF_WANPIPE protocol, so I could be off on this. Your problem may be what you're bind()ing to. About these two lines:

Code:

strncpy((char*)sa.sll_card,"wanpipe1",sizeof(sa.sl l_card));
strncpy((char*)sa.sll_device,"w1g1",sizeof(sa.sll_ device));

What are sizeof(sa.sll_card) and sizeof(sa.sll_device) (Check by printf()ing these sizes) and are they definitely char buffers, not pointers (I suspect so, but I'd check)? Also, is there definitely space to write all of the card/device strings in there with a null-terminator? (Remember strncpy() won't append one if there isn't enough space).

Also, do you realy need to htons(PVC_PROT), or do you just want PVC_PROT? And is it definitely htons(), not htonl() you want?

If all else fails, could you post the definition of the wan_sockaddr_ll struct? I can't seem to find it on my computer.

mrjmrj · 02-13-2013, 05:29 AM

thank you for reply.
i changed the code to:

Code:

strcpy( sa.sll_device,"w1g1");
strcpy( sa.sll_card,"wanpipe1");

but it still does not work

other definition are:

Code:

#define PVC_PROT       	0x17
#define	AF_WANPIPE 	25
struct wan_sockaddr_ll
{
	unsigned short	sll_family;
	unsigned short	sll_protocol;
	int		sll_ifindex;
	unsigned short	sll_hatype;
	unsigned char	sll_pkttype;
	unsigned char	sll_halen;
	unsigned char	sll_addr[8];
	unsigned char   sll_device[14];
	unsigned char 	sll_card[14];

	unsigned int	sll_active_ch;
	unsigned char	sll_prot;
	unsigned char	sll_prot_opt;
	unsigned short  sll_mult_cnt;
	unsigned char	sll_seven_bit_hdlc;
};

i am using a new address family (AF_WANPIPE). maybe i should include some headers files or sth else. do you think so?
in addition bind() does not return error. Does that mean the binding is ok?

JohnGraham · 02-13-2013, 07:27 AM

Quote:

Originally Posted by mrjmrj

maybe i should include some headers files or sth else. do you think so?

Do you get any errors or warnings when you compile? I mean any errors or warnings - pass the -Wall and -Wextra flags to gcc if you're not already, then fix any warnings and retry.

Quote:

Originally Posted by mrjmrj

in addition bind() does not return error. Does that mean the binding is ok?

That means it's bound to *something* - I suspect it's just not the right thing. Try removing the htons() around the PVC_PROT, this may not need to be in network byte order (after all, sa_family doesn't need to be).

How certain are you that the packets you expect are arriving? How are you looking at them? If the above two points don't work, try and get a Wireshark/tcpdump trace that shows the packets you expect to see and post it, along with which specific packets you want to see.

mrjmrj · 02-20-2013, 07:43 AM

thank you JohnGraham
my problem is solved. it was hardware problem

JohnGraham · 02-21-2013, 04:01 AM

Quote:

Originally Posted by mrjmrj

thank you JohnGraham
my problem is solved. it was hardware problem

Glad to hear it. Please mark the thread as solved so other people know without reading through the whole thread - there should be a link just above the first post.