static int inet_read(struct socket *sock, char *ubuf, int size, int noblock)
{
struct sock *sk = (struct sock *) sock->data;
if(sk->err)
return inet_error(sk);
/* We may need to bind the socket. */
if(inet_autobind(sk))
return(-EAGAIN);
return(sk->prot->read(sk, (unsigned char *) ubuf, size, noblock, 0));
}
static int inet_recvfrom(struct socket *sock, void *ubuf, int size, int noblock,
unsigned flags, struct sockaddr *sin, int *addr_len )
{
struct sock *sk = (struct sock *) sock->data;
if (sk->prot->recvfrom == NULL)
return(-EOPNOTSUPP);
if(sk->err)
return inet_error(sk);
/* We may need to bind the socket. */
if(inet_autobind(sk)!=0)
return(-EAGAIN);
return(sk->prot->recvfrom(sk, (unsigned char *) ubuf, size, noblock, flags,
(struct sockaddr_in*)sin, addr_len));
}
static int inet_send(struct socket *sock, void *ubuf, int size, int noblock,
unsigned flags)
{
struct sock *sk = (struct sock *) sock->data;
if (sk->shutdown & SEND_SHUTDOWN)
{
send_sig(SIGPIPE, current, 1); // 向已经关闭的管道中写入数据，返回EPIPE错误
return(-EPIPE);
}
if(sk->err)
return inet_error(sk);
/* We may need to bind the socket. */
if(inet_autobind(sk)!=0)
return(-EAGAIN);
return(sk->prot->write(sk, (unsigned char *) ubuf, size, noblock, flags));
}
static int inet_sendto(struct socket *sock, void *ubuf, int size, int noblock,
unsigned flags, struct sockaddr *sin, int addr_len)
{
struct sock *sk = (struct sock *) sock->data;
if (sk->shutdown & SEND_SHUTDOWN)
{
send_sig(SIGPIPE, current, 1);
return(-EPIPE);
}
if (sk->prot->sendto == NULL)
return(-EOPNOTSUPP);
if(sk->err)
return inet_error(sk);
/* We may need to bind the socket. */
if(inet_autobind(sk)!=0)
return -EAGAIN;
return(sk->prot->sendto(sk, (unsigned char *) ubuf, size, noblock, flags,
(struct sockaddr_in *)sin, addr_len));
}
static int inet_listen(struct socket *sock, int backlog)
{
struct sock *sk = (struct sock *) sock->data;
if(inet_autobind(sk)!=0)
return -EAGAIN;
/* We might as well re use these. */
/*
* note that the backlog is "unsigned char", so truncate it
* somewhere. We might as well truncate it to what everybody
* else does..
*/
if ((unsigned) backlog > 128)
backlog = 128;
sk->max_ack_backlog = backlog;
if (sk->state != TCP_LISTEN)
{
sk->ack_backlog = 0;
sk->state = TCP_LISTEN;
}
return(0);
}
static int inet_connect(struct socket *sock, struct sockaddr * uaddr,
int addr_len, int flags)
{
struct sock *sk=(struct sock *)sock->data;
int err;
sock->conn = NULL;
if (sock->state == SS_CONNECTING && tcp_connected(sk->state))
{
sock->state = SS_CONNECTED;
/* Connection completing after a connect/EINPROGRESS/select/connect */
return 0; /* Rock and roll */
}
if (sock->state == SS_CONNECTING && sk->protocol == IPPROTO_TCP && (flags & O_NONBLOCK)) {
/* INET协议簇中，只有IPPROTO_TCP协议是有可能等待的 */
if (sk->err != 0)
{
err=sk->err;
sk->err=0;
return -err;
}
return -EALREADY; /* Connecting is currently in progress */
}
/* socket第一次调用connect函数，或者udp再次调用；设置socket状态位SS_CONNECTING */
if (sock->state != SS_CONNECTING)
{
/* We may need to bind the socket. */
if(inet_autobind(sk)!=0)
return(-EAGAIN);
if (sk->prot->connect == NULL)
return(-EOPNOTSUPP);
/*
* TCP 更新sk->state为TCP_SYN_SENT
* UDP 更新sk->state为TCP_ESTABLISHED
*/
err = sk->prot->connect(sk, (struct sockaddr_in *)uaddr, addr_len);
if (err < 0)
return(err);
sock->state = SS_CONNECTING;
}
if (sk->state > TCP_FIN_WAIT2 && sock->state==SS_CONNECTING)
{
/*
TCP_TIME_WAIT, 未完成套接字主动关闭中
TCP_CLOSE, 未完成套接字已经关闭
TCP_CLOSE_WAIT,未完成套接字被动关闭中
TCP_LAST_ACK, 未完成套接字被动关闭中
TCP_LISTEN, 异常数据流b、c同时发生，使得客户端socket升级为listen套接字
TCP_CLOSING 未完成套接字主动关闭中
无论哪一种状态，都代表连接过程出错
*/
sock->state=SS_UNCONNECTED;
cli();
err=sk->err;
sk->err=0;
sti();
return -err;
}
// 当前socket状态一定处于SS_CONNECTING状态
// tcp套接字因为设置了O_NONBLOCK选项，会直接返回；保持SS_CONNECTING状态
if (sk->state != TCP_ESTABLISHED &&(flags & O_NONBLOCK))
return(-EINPROGRESS);
// 同步等待tcp连接完成
cli(); /* avoid the race condition */
while(sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV) // 连接过程中唯一合法的两种状态
{
interruptible_sleep_on(sk->sleep);
if (current->signal & ~current->blocked)
{
// 如果进程是被信号唤醒的，就立刻返回ERESTARTSYS错误，并在系统调用返回时处理信号
// 这样就会造成socket调用connect函数时处于SS_CONNECTING状态
sti();
return(-ERESTARTSYS);
}
/* This fixes a nasty in the tcp/ip code. There is a hideous hassle with
icmp error packets wanting to close a tcp or udp socket. */
if(sk->err && sk->protocol == IPPROTO_TCP)
{
sti();
sock->state = SS_UNCONNECTED;
err = -sk->err;
sk->err=0;
return err; /* set by tcp_err() */
}
}
sti();
// 非tcp协议在这里设置SS_CONNECTED标志，
// tcp套接字会在这里，也可以在完成连接时，由内核异步修改
sock->state = SS_CONNECTED;
if (sk->state != TCP_ESTABLISHED && sk->err)
{
sock->state = SS_UNCONNECTED;
err=sk->err;
sk->err=0;
return(-err);
}
return(0);
}
static int inet_connect(struct socket *sock, struct sockaddr * uaddr,
int addr_len, int flags)
{
struct sock *sk=(struct sock *)sock->data;
int err;
sock->conn = NULL;
if (sock->state == SS_CONNECTING && tcp_connected(sk->state))
{
sock->state = SS_CONNECTED;
/* Connection completing after a connect/EINPROGRESS/select/connect */
return 0; /* Rock and roll */
}
if (sock->state == SS_CONNECTING && sk->protocol == IPPROTO_TCP && (flags & O_NONBLOCK)) {
if (sk->err != 0)
{
err=sk->err;
sk->err=0;
return -err;
}
return -EALREADY; /* Connecting is currently in progress */
}
if (sock->state != SS_CONNECTING)
{
/* We may need to bind the socket. */
if(inet_autobind(sk)!=0)
return(-EAGAIN);
if (sk->prot->connect == NULL)
return(-EOPNOTSUPP);
err = sk->prot->connect(sk, (struct sockaddr_in *)uaddr, addr_len);
if (err < 0)
return(err);
sock->state = SS_CONNECTING;
}
if (sk->state > TCP_FIN_WAIT2 && sock->state==SS_CONNECTING)
{
sock->state=SS_UNCONNECTED;
cli();
err=sk->err;
sk->err=0;
sti();
return -err;
}
if (sk->state != TCP_ESTABLISHED &&(flags & O_NONBLOCK))
return(-EINPROGRESS);
cli(); /* avoid the race condition */
while(sk->state == TCP_SYN_SENT || sk->state == TCP_SYN_RECV)
{
interruptible_sleep_on(sk->sleep);
if (current->signal & ~current->blocked)
{
sti();
return(-ERESTARTSYS);
}
/* This fixes a nasty in the tcp/ip code. There is a hideous hassle with
icmp error packets wanting to close a tcp or udp socket. */
if(sk->err && sk->protocol == IPPROTO_TCP)
{
sti();
sock->state = SS_UNCONNECTED;
err = -sk->err;
sk->err=0;
return err; /* set by tcp_err() */
}
}
sti();
sock->state = SS_CONNECTED;
if (sk->state != TCP_ESTABLISHED && sk->err)
{
sock->state = SS_UNCONNECTED;
err=sk->err;
sk->err=0;
return(-err);
}
return(0);
}