Hello,
i'm using kernel version 2.2.14 and try to make a
tcp/ip socket for sending messages between a
server (located in userspace) and the client
(located in kernelspace).
There is no problem by sending from user to kernel,
but if I try to send a message back (kernel -> user),
nothing happens (0 bytes are send and nothing comes
to the userspace).
So I made some tiny codeletts for you, hoping you'll
see where the problem is.
1. start 'testserver'
2. insmod testsocket.o [output goes to /var/og/messages]
====================================================
/* testserver.c */
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <fcntl.h>
static void err(char *msg)
{
printf("Server ERROR(%d): %s\n", errno, msg);
exit(1);
}
int main(int argc, char **argv)
{
struct sockaddr_in sock, client;
int i, s, cs, sock_len, client_len;
char cmd[] = "this is a test";
struct msghdr msg;
struct iovec iov;
printf("starting service\n");
sock.sin_family = AF_INET;
sock.sin_port = 3333;
sock.sin_addr.s_addr = 0x0100007f;
if ((s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
err("server: socket");
printf("Server: create socket.\n");
sock_len = sizeof(sock);
if (bind(s, &sock, sock_len) < 0)
err("server: bind");
printf("Server: bind socket.\n");
if (listen(s, 5) < 0)
err("server: listen");
printf("Server: listen socket.\n");
if ((cs = accept(s, &client, &client_len)) < 0)
err("server: accept");
printf("Server: accept socket.\n");
/* fcntl(cs, O_NONBLOCK); */
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
iov.iov_base = cmd;
iov.iov_len = sizeof(cmd);
if ((i = sendmsg(cs, &msg, MSG_DONTWAIT)) < 0)
err("server: sendmsg");
printf("Server: sendmsg(%i): '%s'.\n", i, cmd);
if ((i = recvmsg(cs, &msg, MSG_DONTWAIT)) < 0)
err("server: recvmsg");
printf("Server: recvmsg(%i): '%s'.\n", i, (char *) iov.iov_base);
return 0;
}
================================================================
/* testsocket.c */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <linux/un.h>
#include <linux/in.h>
#include <linux/malloc.h>
#include <asm/uaccess.h>
int init_module(void)
{
printk("testsocket: init_module()\n");
{
struct sockaddr_in addr;
struct socket *sock;
struct msghdr msg;
struct iovec iov;
char kdata[] = ".............";
char sdata[] = "ein neuer test";
mm_segment_t oldfs;
int error;
error = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
if (error < 0)
printk("testsocket: Error during creation of socket; terminating\n");
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = 0x0100007f;
addr.sin_port = 3333;
error = sock->ops->connect(sock, (struct sockaddr *) &addr,
sizeof(addr), O_RDWR);
if (error < 0)
printk("testsocket: Error during connect; terminating\n");
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
iov.iov_base = kdata;
iov.iov_len = sizeof(kdata);
oldfs = get_fs(); set_fs(get_ds());
error = sock_recvmsg(sock, &msg, sizeof(msg), MSG_DONTWAIT);
if(error < 0)
printk("testsocket: Error during sock_recvmsg; terminating\n");
printk("testsocket: kdata: '%s'\n", kdata);
iov.iov_base = sdata;
iov.iov_len = sizeof(sdata);
error = sock_sendmsg(sock, &msg, sizeof(msg));
if(error < 0)
printk("testsocket: Error during sock_sendmsg; terminating\n");
printk("testsocket: sendmsg(%d): '%s'\n", error, (char *) iov.iov_base);
}
return 0;
}
void cleanup_module(void)
{
printk("testsocket: cleanup_module()\n");
}
===============================================================
# Makefile
CC=gcc
CFLAGS := -Wall -DLINUX
MODCFLAGS := $(CFLAGS) -DMODULE -D__KERNEL__
all: testsocket.o testserver
testsocket.o: testsocket.c /usr/include/linux/version.h
$(CC) $(MODCFLAGS) -I/usr/src/linux/include -c testsocket.c
testserver: testserver.c
$(CC) $(CFLAGS) -o testserver testserver.c
===================================================================
thanx a lot,
Sebastian Frankfurt
PS: Please do a CC on my e-mail: mailto: fortune@gmx.de
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This archive was generated by hypermail 2b29 : Fri Jun 23 2000 - 21:00:21 EST