I am learning how to write Linux Device Driver.
I wrote a dummy character device driver, implemented open, release, write, read in fops;
When I read from device , everything was ok;
When I wrote to device by "echo xx > ", the OS was hang.
Even I comment out all codes in write function except pr_alert and return statements, It still hangs;
Could anybody help me figure it out?
#include <linux/init.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/string.h>
struct hello_dev
{
char *buffer;
int length;
dev_t dev;
struct mutex lock;
struct cdev *pcdev;
};
struct hello_dev *pHelloDev;
int open_device(struct inode *pinode, struct file *filp)
{
filp->private_data = pHelloDev;
return 0;
}
int close_device(struct inode *pinode, struct file *filp)
{
struct hello_dev *pDev = filp->private_data;
if (pDev->buffer != NULL)
kfree(pDev->buffer);
pDev->buffer = NULL;
return 0;
}
ssize_t read_device(struct file *filp, char __user *buffer, size_t len, loff_t *loff)
{
pr_alert("read\n");
struct hello_dev *pDev = filp->private_data;
mutex_lock(&pDev->lock);
if (pDev->buffer == NULL)
{
mutex_unlock(&pDev->lock);
return 0;
}
int length = strlen(pDev->buffer);
// offset max than strlen in buffer, return
if (*loff > (length - 1))
{
mutex_unlock(&pDev->lock);
return 0;
} else {
// available to read
int len2read = length - *loff;
if (len < len2read)
{// buffer length less than available data
len2read = len;
}
int read = copy_to_user(buffer, pDev->buffer + *loff, len2read);
if (read)
{
*loff = *loff + read;
mutex_unlock(&pDev->lock);
return read;
} else {
*loff = *loff + len2read;
mutex_unlock(&pDev->lock);
return len2read;
}
}
}
ssize_t write_device(struct file *filp , const char __user *buffer, size_t len, loff_t* loff) {
pr_alert("write %s\n", buffer);
// struct hello_dev *pDev = filp->private_data;
// mutex_lock(&pDev->lock);
// if(pDev->buffer == NULL) {
// pDev->buffer = kmalloc(100, GFP_KERNEL);
// pDev->length = 100;
// }
// copy_from_user(pDev->buffer, buffer, len);
// *loff = *loff + len;
// mutex_unlock(&pDev->lock);
return len;
}
struct file_operations fops = {
.open = open_device,
.release = close_device,
.read = read_device,
.write = write_device
};
int init_device(void)
{
pr_alert("init device\n");
pHelloDev = kmalloc(sizeof(struct hello_dev), GFP_KERNEL);
pHelloDev->buffer = NULL;
pHelloDev->length = 0;
int ret = alloc_chrdev_region(&pHelloDev->dev, 0, 1, "hello");
if (ret)
goto alloc_error;
if (pHelloDev == NULL)
goto kmalloc_error;
pHelloDev->pcdev = cdev_alloc();
pHelloDev->pcdev->ops = &fops;
mutex_init(&pHelloDev->lock);
ret = cdev_add(pHelloDev->pcdev, pHelloDev->dev, 1);
if (ret)
goto cdev_add_error;
return 0;
alloc_error:
pr_alert("alloc_chrdev_region error, %d\n", ret);
return ret;
kmalloc_error:
pr_alert("alloc struct hello_dev error");
return -ENOMEM;
cdev_add_error:
pr_alert("cdev_add error, %d\n", ret);
return ret;
}
void cleanup_device(void)
{
pr_alert("unload ko\n");
cdev_del(pHelloDev->pcdev);
unregister_chrdev_region(pHelloDev->dev, 1);
}
MODULE_LICENSE("GPL");
module_init(init_device);
module_exit(cleanup_device);
I found why write to device hangs.
//this statements has problem
//maybe there is no \0 in buffer
//so I print it out, it will hang
//I wrote a program to write something to device
//and used strace to trace system call made by this program
//and found it hangs at write(...) system call
//and there was nothing printed out
//so, it must be this statement causing the problem
//when I removed this statement, everything was ok
pr_alert("write %s\n", buffer);
i am trying adding my own customized layer 4 protocol in linux (ubuntu 14.04) - IPPROTO_MYPROTO as a loadable kernel module. I have done all necessary steps to register the protocol. Here i am sharing my code.
When i am trying to send a mesage from user space program using sendmsg(), i expect the corresponding fn myproto_sendmsg() registered via struct proto structure should be called in kernel space. But what i am observing is that though the myproto_sendmsg() in kernel space is not being called, yet destination machine is receiving the correct data. surprise ! surprise !. Is the default udp sendmsg() fn kicking in here which is like uninvited guest doing his work.
Here, sendmsg() call in user space returns as many bytes as send. Hence, fn returns success.
User space program :
void forwardUDP( int destination_node ,char sendString[] )
{
struct msghdr msg;
destination_node = destination_node % N; //destination node to which data is to be forwaded
int sock, rc;
struct sockaddr_in server_addr;
struct iovec iov;
struct hostent *host; //hostent predefined structure use to store info about host
host = (struct hostent *) gethostbyname(node[destination_node].ip_address);//gethostbyname returns a pointer to hostent
if ((sock = socket(AF_INET, SOCK_RAW, 5)) == -1)
{
perror("socket");
exit(1);
}
//destination address structure
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(node[destination_node].udpportno);
server_addr.sin_addr = *((struct in_addr *)host->h_addr); //host->h_addr gives address of host
bzero(&(server_addr.sin_zero),8);
/* fill the messsage structure*/
memset(&msg, 0 , sizeof(struct msghdr));
memset(&iov, 0, sizeof(struct iovec));
msg.msg_name = (void *)&server_addr;
msg.msg_namelen = sizeof(struct sockaddr_in);
printf("sendString = %s\n", sendString);
iov.iov_base = (void *)sendString;
iov.iov_len = strlen(sendString);
msg.msg_iov = &iov;
printf("len = %d\n", strlen(sendString));
#if 1
msg.msg_iovlen = 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
#endif
//sendto(sock, sendString, strlen(sendString), 0,(struct sockaddr *)&server_addr, sizeof(struct sockaddr));
**rc = sendmsg(sock, &msg, 0);**
printf("rc = %d\n", rc);
//sendto() function shall send a message through a connectionless-mode socket.
printf("\nFORWARD REQUEST : '%s' has been forwarded to node ---->%d\n",sendString,destination_node);
//close(sock);
}
Kernel Module
/* Define the handler which will recieve all ingress packets for protocol = IPPROTO_MYPROTO
defined in net/protocol.h
*/
/* Resgiter the call backs for pkt reception */
static const struct net_protocol myproto_protocol = {
.handler = myproto_rcv,
.err_handler = myproto_err,
.no_policy = 1,
.netns_ok = 1,
};
static struct inet_protosw myproto_protosw;
int
myproto_rcv(struct sk_buff *skb){
printk(KERN_INFO "myproto_rcv is called\n");
return 0;
}
int
myproto_sendmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg, size_t len){
printk(KERN_INFO "myproto_sendmsg() is called\n");
return 0;
}
void myproto_lib_close(struct sock *sk, long timeout){
printk(KERN_INFO "close is called\n");
return;
}
int
myproto_recvmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg,
size_t len, int noblock, int flags,
int *addr_len){
printk(KERN_INFO "myproto_recvmsg() is called.\n");
printk(KERN_INFO "iocb = 0x%x,\nsk = 0x%x,\nmsg = 0x%x,\nlen = %d,\nnoblock = %d,\nflags = %d,\naddr_len = 0x%x", iocb, sk, msg, len, noblock, flags, addr_len);
return 0;
}
/* Socket structure for Custom protocol, see struct udp_sock for example*/
struct myproto_sock{
struct inet_sock inet; // should be first member
__u16 len;
};
void
myproto_lib_hash(struct sock *sk){
printk(KERN_INFO "myproto_lib_hash() is called");
}
/* Define the **struct proto** structure for the Custom protocol defined in
net/sock.h */
struct proto myproto_prot = {
.name = "MYPROTO",
.owner = THIS_MODULE,
.close = myproto_lib_close,
.sendmsg = myproto_sendmsg,
.hash = myproto_lib_hash,
.recvmsg = myproto_recvmsg,
.obj_size = sizeof(struct myproto_sock),
.slab_flags = SLAB_DESTROY_BY_RCU,
};
int init_module(void);
void cleanup_module(void);
int
init_module(void)
{
int rc = 0;
rc = proto_register(&myproto_prot, 1);
if(rc == 0){
printk(KERN_INFO "Protocol registration is successful\n");
}
else{
printk(KERN_INFO "Protocol registration is failed\n");
cleanup_module();
return rc;
}
rc = inet_add_protocol(&myproto_protocol, IPPROTO_MYPROTO);
if(rc == 0){
printk(KERN_INFO "Protocol insertion in inet_protos[] is successful\n");
}
else{
printk(KERN_INFO "Protocol insertion in inet_protos[] is failed\n");
cleanup_module();
return rc;
}
memset(&myproto_protosw, 0 ,sizeof(myproto_protosw));
myproto_protosw.type = SOCK_RAW;
myproto_protosw.protocol = IPPROTO_MYPROTO;
myproto_protosw.prot = &myproto_prot;
extern const struct proto_ops inet_dgram_ops; // defined in ipv4/af_inet.c
myproto_protosw.ops = &inet_dgram_ops;
myproto_protosw.flags = INET_PROTOSW_REUSE;
inet_register_protosw(&myproto_protosw);
return 0;
}
void cleanup_module(void)
{
int rc = 0;
rc = inet_del_protocol(&myproto_protocol, IPPROTO_MYPROTO);
if(rc == 0)
printk(KERN_INFO "Protocol removed successful\n");
else
printk(KERN_INFO "Protocol removal failed\n");
proto_unregister(&myproto_prot);
printk(KERN_INFO "Module cleaned up\n");
return;
}
I am trying to do Socket programming. I've google and looked at problems like mine. However, I can't see to figure out my error.
Whenever I run my code, I get an error in connect() in main in client.c. The error is invalid argument.
Server.c
/* chatroom server */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
#include <pthread.h>
#include <signal.h>
#define MAX_ROOMS 36
#define MAX_NAME_SIZE 56
#define PORT_NUM 12333
#define MSG_SIZE 8
#define MAX_LOAD 246
#define MAX_CRC 64 //max clients
#define MAX_BUF 256
#define SERVER_IP 32
#define DEBUG 0
struct msg {
int type; //create, join, delete
int length; // length or port num
};
struct chat_room {
int socket_d; //socket descriptor
int port;
pthread_t id; //id of chatroom
char name[MAX_NAME_SIZE];
int clients[MAX_ROOMS]; // used to hold the client's master sockets
};
struct chat_room* findRoom(char* name, struct chat_room* chat){
int iterator;
for(iterator = 0; iterator < MAX_ROOMS; iterator++){
if(strcmp(name, chat[iterator].name) && (chat[iterator].port != 0)) {
return &chat[iterator];
}
}
//if room does not exist
return NULL;
}
struct chat_room* joinServer(int chat_socket, char* name, struct chat_room* chat){
struct chat_room* local_chat = findRoom(name, chat);
int i;
if(local_chat != NULL){ //if the chat exists
for(i= 0; i< MAX_CRC; i++){
if(local_chat->clients[i] == 0)
{
local_chat->clients[i] = chat_socket;
}
return local_chat;
}
}
//if server if full or else error
return NULL;
}
int createResponse(int chat_socket, int new_port_num, int type){
struct msg temp;
char temp_buff[MAX_LOAD];
memset(temp_buff, 0, MAX_LOAD);
temp.type = type;
temp.length = new_port_num;
memcpy(temp_buff, &temp, sizeof(temp));
write(chat_socket, temp_buff, MSG_SIZE);
return 0;
}
int joinResponse(int chat_socket, int new_port_num){
struct msg temp;
char temp_buff[MAX_LOAD];
memset(temp_buff, 0, MAX_LOAD);
temp.type = 11;
temp.length = new_port_num;
memcpy(temp_buff, &temp, sizeof(temp));
write(chat_socket, temp_buff, MSG_SIZE);
return 0;
}
int deleteResponse(int chat_socket, struct chat_room* chat){
struct msg temp;
char temp_buff[MAX_LOAD];
int i;
memset(temp_buff, 0, MAX_LOAD);
temp.type = 12;
memcpy(temp_buff, &temp, sizeof(temp));
for(i=0; i<MAX_CRC; i++){
if((chat->clients[i] != chat_socket) && (chat->clients[i] != 0))
write(chat->clients[i],temp_buff, MSG_SIZE);
}
return 0;
}
struct chat_room* addRoom(int chat_socket, char* name, struct chat_room* chat){
int socket_d;
int i;
struct sockaddr_in sock;
static int port = PORT_NUM;
memset(&sock, 0, sizeof(sock));
int temp = -1;
for(i = 0; i<MAX_ROOMS; i++){
if((strcmp(chat[i].name, name) == 0) && (chat[i].port != 0)){
createResponse(chat_socket, chat[i].port, 15);
return NULL;
}
else if((chat[i].port == 0) && (temp== -1)){
temp = i;
}
}
if(temp == -1){
return NULL;
}
socket_d = socket(AF_INET, SOCK_STREAM, 0);
if(socket_d == -1 && DEBUG){
perror("Error creating chatroom socket");
return NULL;
}
sock.sin_family = AF_INET;
port++;
sock.sin_port = htons(port);
if(bind(socket_d, (struct sockaddr*)&sock, sizeof(struct sockaddr_in)) == -1){
perror("error in binding ");
return NULL;
}
chat[temp].socket_d = socket_d;
chat[temp].port = port;
strcpy(chat[temp].name, name);
return &chat[temp];
}
void* chat_room_main(void* chat_room_cluster){
char buf[MAX_LOAD];
int socket_d, chat_socket;
int temp; //temp_fd
int read_val;
int num_clients = 0;
int i;
int clients[MAX_CRC];
fd_set allfd, modfd;
struct chat_room chat_room_para;
memcpy(&chat_room_para, (struct chat_room*)chat_room_cluster, sizeof(struct chat_room));
free(chat_room_cluster);
memset(clients, 0, sizeof(int)*MAX_CRC);
socket_d = chat_room_para.socket_d;
listen(socket_d, 1);
FD_ZERO(&allfd);
FD_SET(socket_d, &allfd);
printf("New Chatroom Started\n");
while(1){
modfd = allfd;
select(FD_SETSIZE, &modfd, NULL, NULL, NULL);
for(temp = 0; temp < FD_SETSIZE; temp++){
if(FD_ISSET(temp, &modfd)){
memset(buf, 0, sizeof(buf));
if(temp == socket_d) {
chat_socket = accept(socket_d, NULL, NULL);
FD_SET(chat_socket, &allfd);
// find an empty spot to add the chat room
for(i = 0; i<MAX_CRC; i++) {
if(clients[i] == 0){
clients[i] = chat_socket;
break;
}
}
sprintf(buf, "Number of people in chatroom: %d", num_clients);
write(chat_socket, buf, strlen(buf));
num_clients++;
}
else{
if(read_val = read(temp, buf, MAX_LOAD) > 0){
for(i = 0; i< MAX_CRC; i++){
if((clients[i] != temp) && (clients[i] != 0)){
write(clients[i], buf, read_val);
}
}
}
else if(read_val <= 0) {
FD_CLR(temp, &allfd);
for(i = 0; i<MAX_CRC; i++){
if(clients[i] == temp)
clients[i] = 0;
}
num_clients--;
close(chat_socket);
}
}
}
}
}
}
int main(int argc, char* argv[]){
int server_socket, chat_socket; //file descriptors for server and chat
int temp; //tempfd
int i, j;
char server_ip[SERVER_IP];
char buf[MAX_BUF];
char msg_buf[MSG_SIZE];
fd_set allfd, modfd;
struct sockaddr_in sock;
struct hostent* host_name;
struct chat_room chatrooms[MAX_ROOMS];
memset(chatrooms, '\0', sizeof(struct chat_room)* MAX_ROOMS);
memset(&sock, '\0', sizeof(sock));
server_socket = socket(AF_INET, SOCK_STREAM, 0);
if(server_socket == -1){
perror("Error creating socket");
return -1;
}
sock.sin_family = AF_INET;
sock.sin_port = htons(PORT_NUM);
sock.sin_addr.s_addr = INADDR_ANY;
if((bind(server_socket, (struct sockaddr*)&sock, sizeof(struct sockaddr_in))) == -1){
perror("Error in bind()");
return -1;
}
listen(server_socket, 1);
FD_ZERO(&allfd);
FD_SET(server_socket, &allfd);
FD_SET(0, &allfd);
printf("\n*******Chatroom Server*******");
while(1){
modfd = allfd;
select(FD_SETSIZE, &modfd, NULL, NULL, NULL);
for(temp = 0; temp < FD_SETSIZE; temp++) {
if(FD_ISSET(temp, &modfd)) {
switch(temp){
case 0:
break;
default:
if(temp == server_socket){
chat_socket = accept(server_socket, NULL, NULL);
}
else{
char msg_buf[MSG_SIZE];
char buf[MAX_LOAD];
char name[MAX_LOAD];
struct msg temp_message;
struct chat_room* local_chat = NULL;
void* (*init_chatroom)() = &chat_room_main;
void* thread_args;
pthread_attr_t attr;
pthread_t tid;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
memset(buf, 0, sizeof(buf));
memset(msg_buf, 0, sizeof(msg_buf));
msg_buf[19]= 0;
int read_val = read(temp, msg_buf, MSG_SIZE);
if(read_val > 0){
memcpy(&temp_message, msg_buf, sizeof(temp_message));
read(temp, buf, temp_message.length - sizeof(temp_message));
memcpy(name, buf, temp_message.length - sizeof(temp_message));
if(temp_message.type == 0) {//if create
local_chat = addRoom(temp, name, chatrooms);
if(local_chat != NULL){
thread_args = (void*)malloc(sizeof(struct chat_room));
memcpy((struct chat_room*) thread_args, local_chat, sizeof(struct chat_room));
pthread_create(&tid, &attr, init_chatroom, thread_args);
local_chat->id = tid;
createResponse(temp, local_chat->port, 10);
}
}
else if(temp_message.type == 1){ //join
local_chat = joinServer(temp, name, chatrooms);
if(local_chat != NULL){
joinResponse(temp, local_chat->port);
}
}
else if(temp_message.type == 2){ //delete
local_chat = findRoom(name, chatrooms);
printf("Deleting Room\n");
if(local_chat != NULL) {
local_chat->port = 0;
close(local_chat->socket_d);
deleteResponse(temp, local_chat);
for(j = 0; j<MAX_CRC; j++){
if(local_chat->clients[j]!=0) {
FD_CLR(local_chat->clients[j], &modfd);
local_chat->clients[j] = 0;
}
}
pthread_cancel(local_chat->id);
}
}
}
else if(read_val <= 0){
FD_CLR(temp, &allfd);
close(temp);
}
}
}
}
}
}
return 0;
}
Client.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
#include <pthread.h>
#define PORT_NUM 12333
#define MSG_SIZE 8
#define MAX_LOAD 246
#define MAX_BUF 256
#define SERVER_IP 32
struct msg {
int type;
int length;
};
struct thread_para {
int port;
struct hostent* host_name;
};
int sendCmd(int chat_socket, char* buf, int type){ //function for sending the command
struct msg temp;
char temp_buf[MAX_LOAD];
char name[MAX_LOAD];
int iterator;
if(type == 0){
iterator = 6;
}
else if(type == 1){
iterator = 4;
}
else if(type == 2){
iterator = 6;
}
for(; iterator < strlen(buf); iterator++){
if(buf[iterator] == ' ') {
continue;
}
else{
break;
}
}
strcpy(name, buf+iterator);
memset(temp_buf, 0, MAX_LOAD);
temp.type = type;
temp.length = sizeof(temp)+strlen(name)+1; //for \0
memcpy(temp_buf, &temp, sizeof(temp));
memcpy(temp_buf+sizeof(temp), name, strlen(name)+1);
write(chat_socket, temp_buf, temp.length);
return 0;
}
void* connectChat(int port_num, struct hostent* host_name, int master){
char buf[MAX_BUF];
char temp_buf[MAX_BUF];
int chat_socket;
int i;
int input;
int temp; //temp fd
fd_set allfd, modfd;
struct sockaddr_in sock;
printf("Successfully Joined Room\n");
memset(buf, 0, sizeof(buf));
memset(&sock, 0, sizeof(sock));
sock.sin_family = AF_INET;
sock.sin_port = htons(port_num);
memcpy((char*)&sock.sin_addr.s_addr, host_name->h_addr, host_name->h_length);
chat_socket = socket(AF_INET, SOCK_STREAM, 0);
if(chat_socket == -1){
perror("Error in creation");
return NULL;
}
if(connect(chat_socket, (struct sockaddr*)&sock, sizeof(struct sockaddr)) < 0 ){
perror("Error in connection");
return NULL;
}
FD_ZERO(&allfd);
FD_SET(chat_socket, &allfd);
FD_SET(0, &allfd);
FD_SET(master, &allfd);
while(1) {
modfd = allfd;
select(FD_SETSIZE, &modfd, NULL, NULL, NULL);
for(temp = 0; temp< FD_SETSIZE; temp++){
memset(buf, 0, sizeof(buf));
memset(temp, 0, sizeof(buf));
if(temp == 0) { //reading from standard in
input = read(0, buf, MAX_BUF);
buf[input-1] = '\0'; //add termination to end
write(chat_socket, buf, strlen(buf));
}
else if(temp == chat_socket){
input = read(0, buf, MAX_BUF);
buf[input] = '\0';
memcpy(temp, buf, input);
//display message
printf("%s \n", temp_buf);
}
else if(temp == master){
struct msg temp_message;
input = read(temp, buf, MSG_SIZE);
memcpy(&temp_message, buf, MSG_SIZE);
if(temp_message.type == 12){
printf("Chatroom has been deleted, Shutting down chatroom\n");
return NULL;
}
}
}
}
return 0;
}
int main(int argc, char* argv[]){
char buf[MAX_BUF];
int chat_socket;
int i;
int input;
int temp; //temp fd
int accept_input = 1; // take input for stdin to create a chat thread
fd_set allfd, modfd;
char server_ip[SERVER_IP];
struct hostent* host_name;
struct sockaddr_in sock;
struct msg temp_message;
pthread_attr_t tattr;
pthread_t tid;
if(argc < 2) {
printf("Please try ./crc <server IP> \n");
return -1;
}
pthread_attr_init(&tattr);
pthread_attr_setdetachstate(&tattr, PTHREAD_CREATE_DETACHED);
memset(&sock, '\0', sizeof(sock));
sock.sin_family = AF_INET;
sock.sin_port = htons(PORT_NUM);
strcpy(server_ip ,argv[1]);
if((host_name = (struct hostent*)gethostbyname(server_ip)) == NULL){
perror("failed to get host name");
return -1;
}
memcpy((char*)&sock.sin_addr.s_addr, host_name->h_addr, host_name->h_length);
chat_socket = socket(AF_INET, SOCK_STREAM, 0);
if(chat_socket == -1){
perror("Error creating socket");
return -1;
}
if((connect(chat_socket, (struct sockaddr*)&sock, sizeof(sock))) < 0) {
perror("Error connecting");
return -1;
}
FD_ZERO(&allfd); /* first, clear the allfd set */
FD_SET(chat_socket, &allfd); /* adding client to the set */
FD_SET(0, &allfd);
printf("*****Welcome to the Chatroom*****\n");
while(1){
modfd = allfd;
select(FD_SETSIZE, &modfd, NULL, NULL, NULL);
for(temp = 0; temp < FD_SETSIZE; temp++){
if(FD_ISSET(temp, &modfd)){
if(temp == 0){
input = read(0, buf, MAX_BUF);
buf[input-1] = '\0'; //remove \n inserts termination
if((strncasecmp(buf, "create ", 7) == 0)) {
sendCmd(chat_socket, buf, 0);
}
else if((strncasecmp(buf, "join ", 5) == 0)) {
sendCmd(chat_socket, buf, 1);
}
else if((strncasecmp(buf, "delete ", 7)==0)){
sendCmd(chat_socket, buf, 2);
}
else
{
printf("Enter a valid command: create <Room_name>, join <Room_name>, delete <Room_name>\n");
}
}
else if(temp == chat_socket){
input = read(temp, buf, MSG_SIZE);
memcpy(&temp_message, buf, sizeof(temp_message));
if(temp_message.type == 10) {
printf("Created Chatroom\n");
}
else if(temp_message.type == 11){
connectChat(temp_message.length, host_name, chat_socket);
fflush(stdin);
}
else if(temp_message.type == 15) {
printf("Chatroom exits. Type join <Room_name> to join\n");
}
}
}
}
}
close(chat_socket);
return 0;
}
I gave both sets of code just in case it was need. The program is designed to create multiple chat rooms.
invalid argument is the EINVAL error code, which in the context of connect() means:
An invalid argument was detected (e.g., address_len is not valid for the address family, the specified address family is invalid).
You have multiple calls to connect() in your client code (why?), but you did not indicate which call is the one that is failing. In connectChat() at least, sizeof(struct sockaddr) should be sizeof(struct sockaddr_in) instead, or better sizeof(sock), like you do in main().
Also, if either connect() fails, you are leaking the socket returned by socket(). You need to close() it.
Also, gethostbyname() is deprecated, you should be using getaddrinfo() instead. You are creating IPv4 sockets, which only work with IPv4 addresses. You are not checking if gethostbyname() actually returns an IPv4 address (host_name->h_addr_type == AF_INET) before copying the address bytes into your sock variable. At least with getaddrinfo(), you can restrict the output to IPv4 addresses only. You don't have that option with gethostbyname().
Since you're looking for a way to figure out your error, I'll suggest you to use the following Makefile:
CFLAGS=-Wall -g -O2
CC=gcc
LDFLAGS=-lpthread
all: Server Client
Server: Server.c
Client: Client.c
After running make command you'll see a lot of warnings. Some of them:
Server.c: In function ‘createResponse’:
Server.c:81:5: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
write(chat_socket, temp_buff, MSG_SIZE);
^
Server.c: In function ‘chat_room_main’:
Server.c:237:25: warning: ‘chat_socket’ may be used uninitialized in this function [-Wmaybe-uninitialized]
close(chat_socket);
^
Server.c: In function ‘main’:
Server.c:319:36: warning: array subscript is above array bounds [-Warray-bounds]
msg_buf[19]= 0;
Client.c: In function ‘connectChat’:
Client.c:113:20: warning: passing argument 1 of ‘memset’ makes pointer from integer without a cast
memset(temp, 0, sizeof(buf));
^
So just try to fix these warnings. I mean all of them.
I have similar problem as here:
Netlink sockets and libnl - nl_recvmsgs_default returning -16 (EBUSY)
But nl_recvmsgs_defaul() return this error value -22 (NLE_MSGTYPE_NOSUPPORT).
Does anyone have an idea why I get this error?
Here is example program:
Kernel:
enum {
DOC_EXMPL_A_UNSPEC,
DOC_EXMPL_A_MSG,
__DOC_EXMPL_A_MAX,
};
#define DOC_EXMPL_A_MAX (__DOC_EXMPL_A_MAX - 1)
#define VERSION_NR 1
static struct genl_family doc_exmpl_gnl_family = {
.id = GENL_ID_GENERATE,
.hdrsize = 0,
.name = "CONTROL_EXMPL",
.version = VERSION_NR,
};
enum {
DOC_EXMPL_C_UNSPEC,
DOC_EXMPL_C_ECHO,
__DOC_EXMPL_C_MAX,
};
#define DOC_EXMPL_C_MAX (__DOC_EXMPL_C_MAX - 1)
int doc_exmpl_echo(struct sk_buff *skb_2, struct genl_info *info)
{
struct sk_buff *skb;
struct nlattr *na, *pos;
int len, rem, type, rc;
char * mydata;
void *msg_head;
if (info == NULL)
goto out;
len = nlmsg_attrlen(info->nlhdr, GENL_HDRLEN);
na = nlmsg_attrdata(info->nlhdr, GENL_HDRLEN);
printk(KERN_DEBUG "len1: %d, sizeof: %d ,len: %d", nlmsg_len(info->nlhdr),
GENL_HDRLEN, len);
nla_for_each_attr(pos, na, len, rem) {
type = nla_type(pos);
mydata = (char *) nla_data(pos);
printk(KERN_DEBUG "Type: %d", type);
if (mydata != NULL)
printk(KERN_DEBUG "Data: %s", mydata);
}
skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
if (skb == NULL)
goto out;
msg_head = genlmsg_put(skb, 0, info->snd_seq+1, &doc_exmpl_gnl_family, 0, DOC_EXMPL_C_ECHO);
if (msg_head == NULL) {
rc = -ENOMEM;
goto out;
}
rc = nla_put_u8(skb, DOC_EXMPL_A_MSG, 8);
if (rc != 0)
goto out;
/* finalize the message */
genlmsg_end(skb, msg_head);
//rc = genlmsg_unicast(skb,info->snd_pid );
rc = genlmsg_unicast(genl_info_net(info), skb,info->snd_pid);
if (rc != 0)
goto out;
printk(KERN_DEBUG "End");
return 0;
out:
printk("an error occured in doc_exmpl_echo:\n");
return 0;
}
struct genl_ops doc_exmpl_gnl_ops_echo = {
.cmd = DOC_EXMPL_C_ECHO,
.flags = 0,
.policy = NULL,
.doit = doc_exmpl_echo,
.dumpit = NULL,
};
Userspace code
#include <stdio.h>
#include <stdlib.h>
#include <netlink/netlink.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/ctrl.h>
#include <netlink/socket.h>
#include <netlink/msg.h>
#include <net/if.h>
static int expectedId;
static int nlCallback(struct nl_msg* msg, void* arg)
{
struct nlmsghdr* ret_hdr = nlmsg_hdr(msg);
struct nlattr *tb_msg[2 + 1];
char *str;
if (ret_hdr->nlmsg_type != expectedId)
{
// what is this??
return NL_STOP;
}
struct genlmsghdr *gnlh = (struct genlmsghdr*) nlmsg_data(ret_hdr);
nla_parse(tb_msg, 2, genlmsg_attrdata(gnlh, 0),
genlmsg_attrlen(gnlh, 0), NULL);
if (tb_msg[1]) {
str = nla_get_string(tb_msg[1]);
printf("str: %s", str);
}
return 0;
}
int main(int argc, char **argv) {
int cmd, rc;
struct nl_handle *sk;
struct nl_msg *msg;
//allocate socket
sk = nl_handle_alloc();
//connect to generic netlink
genl_connect(sk);
//find the nl80211 driver ID
expectedId = genl_ctrl_resolve(sk, "CONTROL_EXMPL");
//allocate a message
msg = nlmsg_alloc();
cmd = 1;
int flags = 0;
// setup the message
genlmsg_put(msg, NL_AUTO_PID, NL_AUTO_SEQ, expectedId, 0, NLM_F_REQUEST, cmd, 1);
NLA_PUT_STRING(msg, 3, "Hello test");
nl_send_auto_complete(sk, msg);
nl_socket_modify_cb(sk, NL_CB_VALID, NL_CB_CUSTOM,
nlCallback, NULL);
rc = nl_recvmsgs_default(sk);
printf("rc = %d \n", rc);
nlmsg_free(msg);
return 0;
nla_put_failure:
nlmsg_free(msg);
return 1;
}
OK I found the problem.
I have bad sequencer number in kernel code, it should be:
genlmsg_put(skb, 0, info->snd_seq, &doc_exmpl_gnl_family, 0, DOC_EXMPL_C_ECHO);
It's the same problem as here: Netlink sockets and libnl - nl_recvmsgs_default returning -16 (EBUSY) but I got other error.
I use multuple thread to receive data from one socket. they all can receive the same data. I want to know when the data will be taken away from recv buffer? Why does not one thread receive the next data when former thread read former data.
pthread_create(&(ntid[i]), NULL, find_host, (void *)&start_addr);
int find_host(void * arg)
{
int sockfd;
unsigned long ip ;
tv.tv_sec = 0;
tv.tv_usec = 100000;
struct sockaddr_in from;
char sendpacket[PACKET_SIZE];
char recvpacket[PACKET_SIZE];
ip = *(unsigned long *)arg;
struct sockaddr_in present_addr;
if( (sockfd=socket(AF_INET,SOCK_RAW,protocol->p_proto) )<0)
{
perror("socket error");
exit(1);
}
setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size) );
if(setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv))<0){
printf("socket option SO_RCVTIMEO not support\n");
return;
}
bzero(&present_addr,sizeof(present_addr));
present_addr.sin_family=AF_INET;
present_addr.sin_addr.s_addr = htonl(ip);
pthread_mutex_unlock(&lock);
printf("PING (%s): %d bytes data in ICMP packets.\n",
inet_ntoa(present_addr.sin_addr),ICMP_DATA_LEN);
send_packet(sockfd, sendpacket, present_addr);
recv_packet(sockfd, recvpacket, from);
close(sockfd);
}
void recv_packet(int sockfd, char * recvpacket, struct sockaddr_in from)
{ int n,from_len;
extern int errno;
int nreceived = 0;
struct timeval recv_time;
from_len = sizeof(from);
while (nreceived < MAX_SEND_TIMES)
{
if((n=recvfrom(sockfd,recvpacket, PACKET_SIZE, 0,
(struct sockaddr *)&from,&from_len)) <0)
{
if(errno == EWOULDBLOCK || errno== EAGAIN )
{
printf("recvfrom Timeout!!!!\n");
pthread_exit(NULL);
}
}
gettimeofday(&recv_time,NULL);
if (1 == unpack(recv_time, recvpacket, n, from))
{
printf(" find %u\n", (unsigned short)pthread_self());
nreceived++;
}
else
printf(" not find\n");
}
}