Michael, What you do is correct, but apparently the ctl_enqueuedata() function is buggy. It creates an mbuf with you data but doesn't set the len of the mbuf. Using ctl_enqueuembuf() for the time being. I should just work fine. Christophe. On 10/18/02 4:16 PM, "Michael Cashwell" <mboards@prograde.net> wrote:

Greetings all,

I can almost talk with my NKE from userland but I'm having socket

problems. I can't get any data from the NKE.

I'm using the AF_SYSTEM domain from <sys/kern_control.h>. It

essentially is registering a protocol handler as a SOCK_DGRAM type.

Then from userland I do this (I've deleted the error checking code

below for brevity):

struct sockaddr_ctl sf;

memset(&sf, 0, sizeof(sf));

m_rpcSock = socket(AF_SYSTEM, SOCK_DGRAM, SYSPROTO_CONTROL);

sf.sc_len = sizeof(sf);

sf.sc_family = AF_SYSTEM;

sf.ss_sysaddr = AF_SYS_CONTROL;

sf.sc_id = A1_DARWIN_NKE_SIG;

sf.sc_unit = A1_NKE_UNIT_RPC;

connect(m_rpcSock, (struct sockaddr *)&sf, sizeof(sf);

This all works. I also successfully send one byte of data to the NKE

via:

char dummy = 0;

error = send(m_rpcSock, &dummy, 1, 0);

But then when the userland code call recv() with zero flags it blocks

forever. I then added this diagnostic loop just to verify and recv()

always returns -1 and EAGAIN:

do {

sleep(2);

error = recv(m_rpcSock, ver, sizeof(ver), MSG_DONTWAIT |

MSG_PEEK);

printf("version MSG_PEEK returned %08X, error %d\n", error,

errno);

} while (error != sizeof(ver));

But the log shows that the NKE does receive the one zero byte and in

response does this:

unsigned short ver[2];

ver[0] = IPC_VERSION;

ver[1] = IPC_MIN_SUPPORTED_VERSION;

error = ctl_enqueuedata(ctlref, ver, sizeof(ver), 0);

printf("RPC version send result = %d\n", error);

The log also shows that the ctl_enqueuedata() call returns zero. (I've

also verified that ctlref is the same one the NKE registered.) So it

should have written data to the socket. I can't figure out why the

userland code cannot receive anything.

I've done this sort of thing in the past using SOCK_RAW but the

infrastructure is forcing me to use SOCK_DGRAM. I expect this to raise

some issues in terms of how I read data from the socket but I can

handle that with MSG_PEEK. But only if I can get data to arrive. If

anyone's done this sort of socket code and could assist I'd appreciate

it.

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