/*
 * This file implements handling of socket-related requests from VFS
 */

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>

#include <minix/ipc.h>
#include <minix/com.h>
#include <minix/callnr.h>
#include <minix/sysutil.h>

#include <lwip/tcp.h>

#include <net/ioctl.h>

#include "inet_config.h"
#include "proto.h"
#include "socket.h"

#if 0
#define debug_sock_print(str, ...) printf("LWIP %s:%d : " str "\n", \
		__func__, __LINE__, ##__VA_ARGS__)
#else
#define debug_sock_print(...) debug_print(__VA_ARGS__)
#endif


struct socket socket[MAX_SOCKETS];
static int notified;

#define recv_q_alloc()	debug_malloc(sizeof(struct recv_q))
#define recv_q_free	debug_free

struct mq {
	message		m;
	struct mq *	prev;
	struct mq *	next;
};

#define mq_alloc()	debug_malloc(sizeof(struct mq))
#define mq_free		debug_free

static struct mq * mq_head, *mq_tail;

static int mq_enqueue(message * m)
{
	struct mq * mq;

	debug_sock_print("sock %d op %d", m->DEVICE, m->m_type);
	mq = mq_alloc();

	if (mq == NULL)
		return -1;

	mq->next = NULL;
	mq->m = *m;

	if (mq_head) {
		mq->prev = mq_tail;
		mq_tail->next = mq;
		mq_tail = mq;
	}
	else {
		mq->prev = NULL;
		mq_head = mq_tail = mq;
	}

	return 0;
}

__unused static struct mq * mq_dequeue_head(void)
{
	struct mq * ret;

	if (!mq_head)
		return NULL;

	ret = mq_head;

	if (mq_head != mq_tail) {
		mq_head = mq_head->next;
		mq_head->prev = NULL;
	} else
		mq_head = mq_tail = NULL;
	
	debug_sock_print("socket %d\n", ret->m.DEVICE);

	return ret;
}

static void mq_dequeue(struct mq * mq)
{
	if (mq_head == mq_tail)
		mq_head = mq_tail = NULL;
	else {
		if (mq->prev == NULL) {
			mq_head = mq->next;
			mq_head->prev = NULL;
		} else
			mq->prev->next = mq->next;
		if (mq->next == NULL) {
			mq_tail = mq->prev;
			mq_tail->next = NULL;
		} else
			mq->next->prev = mq->prev;
	}
}

static int mq_cancel(message * m)
{
	struct mq * mq;

	for (mq = mq_tail; mq; mq = mq->prev) {
		if (m->DEVICE == mq->m.DEVICE &&
				m->USER_ENDPT == mq->m.USER_ENDPT &&
				m->IO_GRANT == mq->m.IO_GRANT) {
			debug_sock_print("socket %d\n", mq->m.DEVICE);
			break;
		}
	}

	mq_dequeue(mq);
	mq_free(mq);

	return 1;
}

int sock_enqueue_data(struct socket * sock, void * data, unsigned size)
{
	struct recv_q * r;

	if (!(r = recv_q_alloc()))
		return ENOMEM;

	r->data = data;
	r->next = NULL;

	if (sock->recv_head) {
		sock->recv_tail->next = r;
		sock->recv_tail = r;
	} else {
		sock->recv_head = sock->recv_tail = r;
	}

	assert(size > 0);
	sock->recv_data_size += size;

	return OK;
}

void * sock_dequeue_data(struct socket * sock)
{
	void * data;
	struct recv_q * r;

	if ((r = sock->recv_head)) {
		data = r->data;
		if (!(sock->recv_head = r->next))
			sock->recv_tail = NULL;
		recv_q_free(r);

		return data;
	}

	return NULL;
}

void sock_dequeue_data_all(struct socket * sock,
				recv_data_free_fn data_free)
{
	void * data;

	while ((data = sock_dequeue_data(sock)))
		data_free(data);
	sock->recv_data_size = 0;
}

static void set_reply_msg(message * m, int status)
{
	int proc, ref;

	proc= m->USER_ENDPT;
	ref= (int)m->IO_GRANT;

	m->REP_ENDPT= proc;
	m->REP_STATUS= status;
	m->REP_IO_GRANT= ref;
}

void send_reply(message * m, int status)
{
	int result;

	debug_sock_print("status %d", status);
	set_reply_msg(m, status);
	
	m->m_type = TASK_REPLY;
	result = send(m->m_source, m);
	if (result != OK)
		panic("LWIP : unable to send (err %d)", result);
}

void sock_revive(struct socket * sock, int status)
{
	int result;

	assert(!(sock->flags & SOCK_FLG_OP_REVIVING));
	assert(sock->flags & (SOCK_FLG_OP_PENDING | SOCK_FLG_OP_SUSPENDED));

	if (notified) {
		debug_sock_print("already notified");
		return;
	}
	else {
		assert(sock->mess.m_type != DEV_REVIVE);
		notified = 1;
	}
	
	debug_sock_print("socket num %ld, status %d",
			get_sock_num(sock), status);

	sock->mess.m_type = DEV_REVIVE;
	set_reply_msg(&sock->mess, status);
	
	result = notify(sock->mess.m_source);
	if (result != OK)
		panic("LWIP : unable to notify (err %d)", result);

	sock->flags |= SOCK_FLG_OP_REVIVING;
}

void sock_select_notify(struct socket * sock)
{
	int result;

	debug_sock_print("socket num %ld", get_sock_num(sock));
	assert(sock->select_ep != NONE);

	sock->flags |= SOCK_FLG_SEL_CHECK;
	if (notified) {
		debug_sock_print("already notified");
		return;
	}
	else
		notified = 1;
	
	result = notify(sock->select_ep);
	if (result != OK)
		panic("LWIP : unable to notify (err %d)", result);
}

void sock_reply(struct socket * sock, int status)
{
	debug_sock_print("socket num %ld status %d type %d",
			get_sock_num(sock), status, sock->mess.m_type);
	/*
	 * If the status is SUSPEND send the
	 * message only if this operation wasn't
	 * suspended already, e.g. by enqueing the
	 * message when the socket was busy
	 * because of another pending message
	 *
	 * If there is a pending operation or we a reprocessing a suspended
	 * operation, revive.
	 *
	 * Otherwise send a message straightaway
	 */
	if (status == SUSPEND) {
		if (sock->flags & SOCK_FLG_OP_SUSPENDED) {
			debug_sock_print("suspended before");
			sock->flags &= ~SOCK_FLG_OP_SUSPENDED;
			return;
		}
		message m = sock->mess;
		debug_sock_print("SUSPEND");
		send_reply(&m, status);
	} else if (sock->flags & (SOCK_FLG_OP_PENDING | SOCK_FLG_OP_SUSPENDED)) {
		sock_revive(sock, status);
		/*
		 * From now on, we process suspended calls as any other. The
		 * status is set and will be collected
		 */
		sock->flags &= ~SOCK_FLG_OP_SUSPENDED;
	} else
		send_reply(&sock->mess, status);
}

struct socket * get_unused_sock(void)
{
	int i;

	for (i = SOCK_TYPES + MAX_DEVS; i < MAX_SOCKETS; i++) {
		if (socket[i].ops == NULL) {
			/* clear it all */
			memset(&socket[i], 0, sizeof(struct socket));
			return &socket[i];
		}
	}

	return NULL;
}

struct socket * get_nic_sock(unsigned dev)
{
	if (dev < MAX_DEVS)
		return &socket[dev + SOCK_TYPES];
	else
		return NULL;
}

static void socket_open(message * m)
{
	struct sock_ops * ops;
	struct socket * sock;
	int ret = OK;

	switch (m->DEVICE) {
	case SOCK_TYPE_TCP:
		ops = &sock_tcp_ops;
		break;
	case SOCK_TYPE_UDP:
		ops = &sock_udp_ops;
		break;
	case SOCK_TYPE_IP:
		ops = &sock_raw_ip_ops;
		break;
	default:
		if (m->DEVICE - SOCK_TYPES  < MAX_DEVS) {
			m->DEVICE -= SOCK_TYPES;
			nic_open(m);
			return;
		}
		printf("LWIP unknown socket type %d\n", m->DEVICE);
		send_reply(m, EINVAL);
		return;
	}
	
	sock = get_unused_sock();
	if (!sock) {
		printf("LWIP : no free socket\n");
		send_reply(m, EAGAIN);
		return;
	}

	sock->ops = ops;
	sock->select_ep = NONE;
	sock->recv_data_size = 0;

	if (sock->ops && sock->ops->open)
		ret = sock->ops->open(sock, m);
	
	if (ret == OK) {
		debug_sock_print("new socket %ld", get_sock_num(sock));
		send_reply(m, get_sock_num(sock));
	} else {
		debug_sock_print("failed %d", ret);
		send_reply(m, ret);
	}
}

static void do_status(message * m)
{
	int i;

	debug_sock_print("called");

	notified = 0;

	for (i = 0; i < MAX_SOCKETS; i++) {
		struct socket * sock = &socket[i];
		if (!sock->ops) {
			continue;
		}
		if (sock->flags & (SOCK_FLG_OP_REVIVING)) {
			/*
			 * We send the reply and we are done with this request
			 */
			debug_sock_print("status %d ep %d sent sock %ld type %d", 
					sock->mess.REP_STATUS,
					sock->mess.REP_ENDPT,
					get_sock_num(sock),
					sock->mess.m_type);
			send(m->m_source, &sock->mess);
			/*
			 * Remove only the reviving flag, i.e. the status has
			 * been consumed. SOCK_FLG_OP_PENDING may stay set. For
			 * instance in case of a TCP write, the application is
			 * already notified while the process of sending is
			 * still going on
			 */
			sock->flags &= ~SOCK_FLG_OP_REVIVING;
			return;
		}

		/*
		 * We check select AFTER possible reviving an operation,
		 * otherwise the select will fail as the socket is still
		 * blocking
		 */
		if (sock_select_check_set(sock)) {
			if (sock->ops && sock->ops->select_reply) {
				message msg;
				msg.m_type = DEV_IO_READY;
				msg.DEV_MINOR = get_sock_num(sock);
				msg.DEV_SEL_OPS = 0;
				sock->ops->select_reply(sock, &msg);
				if (msg.DEV_SEL_OPS) {
					int result;

					debug_sock_print("socket num %d select "
						"result 0x%x sent",
						msg.DEV_MINOR,
						msg.DEV_SEL_OPS);
					result = send(sock->select_ep, &msg);
					if (result != OK)
						panic("LWIP : unable to send "
							"(err %d)", result);
					sock_clear_select(sock);
					sock->select_ep = NONE;
					return;
				}
			}
		}
	}

	debug_sock_print("no status");
	m->m_type = DEV_NO_STATUS;
	send(m->m_source, m);
}

static void socket_request_socket(struct socket * sock, message * m)
{
	switch (m->m_type) {
	case DEV_READ_S:
		if (sock && sock->ops && sock->ops->read)
			sock->ops->read(sock, m);
		else
			send_reply(m, EINVAL);
		return;
	case DEV_WRITE_S:
		if (sock && sock->ops && sock->ops->write)
			sock->ops->write(sock, m);
		else
			send_reply(m, EINVAL);
		return;
	case DEV_IOCTL_S:
		if (sock && sock->ops && sock->ops->ioctl)
			sock->ops->ioctl(sock, m);
		else
			send_reply(m, EINVAL);
		return;
	default:
		panic("LWIP : cannot happen!");
	}
}

void socket_request(message * m)
{
	struct socket * sock;

	switch (m->m_type) {
	case DEV_OPEN:
		socket_open(m);
		return;
	case DEV_CLOSE:
		sock = get_sock(m->DEVICE);
		if (sock && sock->ops && sock->ops->close) {
			sock->flags &= ~SOCK_FLG_OP_PENDING;
			sock->mess = *m;
			sock->ops->close(sock, m);
		} else
			send_reply(m, EINVAL);
		return;
	case DEV_READ_S:
	case DEV_WRITE_S:
	case DEV_IOCTL_S:
		sock = get_sock(m->DEVICE);
		if (!sock) {
			send_reply(m, EINVAL);
			return;
		}
		/*
		 * If an operation is pending (blocking operation) or writing is
		 * still going and we want to read, suspend the new operation
		 */
		if ((sock->flags & (SOCK_FLG_OP_PENDING | SOCK_FLG_OP_REVIVING)) |
				(m->m_type == DEV_READ_S &&
				 sock->flags & SOCK_FLG_OP_WRITING)) {
			char * o = "\0";
			if (sock->flags & SOCK_FLG_OP_READING)
				o = "READ";
			else if (sock->flags & SOCK_FLG_OP_WRITING)
				o = "WRITE";
			else
				o = "non R/W op";
			debug_sock_print("socket %ld is busy by %s\n",
					get_sock_num(sock), o);
			if (mq_enqueue(m) == 0) {
				send_reply(m, SUSPEND);
			} else {
				debug_sock_print("Enqueuing suspended "
							"call failed");
				send_reply(m, ENOMEM);
			}
			return;
		}
		sock->mess = *m;
		socket_request_socket(sock, m);
		return;
	case CANCEL:
		sock = get_sock(m->DEVICE);
		debug_sock_print("socket num %ld", get_sock_num(sock));
		/* Cancel the last operation in the queue */
		if (mq_cancel(m)) {
			send_reply(m, EINTR);
			return;
		/* ... or a blocked read */
		} else if (sock->flags & SOCK_FLG_OP_PENDING &&
				sock->flags & SOCK_FLG_OP_READING) {
			sock->flags &= ~SOCK_FLG_OP_PENDING;
			send_reply(m, EINTR);
			return;
		/*
		 * .. or return the status of the operation which was finished
		 * before canceled
		 */
		} else if (sock->flags & SOCK_FLG_OP_REVIVING) {
			sock->flags &= ~SOCK_FLG_OP_REVIVING;
			send_reply(m, sock->mess.REP_STATUS);
		} else
			panic("LWIP : no operation to cancel");

		return;
	case DEV_SELECT:
		/* 
		 * Select is always executed immediately and is never suspended.
		 * Although, it sets actions which must be monitored
		 */
		sock = get_sock(m->DEVICE);
		assert(sock->select_ep == NONE || sock->select_ep == m->m_source);
		
		if (sock && sock->ops && sock->ops->select) {
			sock->ops->select(sock, m);
			if (sock_select_set(sock))
				sock->select_ep = m->m_source;
		} else
			send_reply(m, EINVAL);
		return;
	case DEV_STATUS:
		do_status(m);
		return;
	default:
		printf("LWIP : unknown message from VFS, type %d\n",
							m->m_type);
	}
	send_reply(m, EGENERIC);
}

void mq_process(void)
{
	struct mq * mq;
	struct socket * sock;

	mq = mq_head;

	while(mq) {
		struct mq * next = mq->next;
	
		sock = get_sock(mq->m.DEVICE);
		if (!(sock->flags &
				(SOCK_FLG_OP_PENDING | SOCK_FLG_OP_REVIVING)) &&
				!(mq->m.m_type == DEV_READ_S &&
				 sock->flags & SOCK_FLG_OP_WRITING)) {
			sock->flags = SOCK_FLG_OP_SUSPENDED;
			debug_sock_print("resuming op on sock %ld\n",
					get_sock_num(sock));
			sock->mess = mq->m;
			socket_request_socket(sock, &sock->mess);
			mq_dequeue(mq);
			mq_free(mq);
			return;
		}

		mq = next;
	}
}

void generic_op_select(struct socket * sock, message * m)
{
	int retsel = 0, sel;

	debug_print("socket num %ld 0x%x", get_sock_num(sock), m->USER_ENDPT);

	sel = m->USER_ENDPT;

	/* in this case any operation would block, no error */
	if (sock->flags & SOCK_FLG_OP_PENDING) {
		if (sel & SEL_NOTIFY) {
			if (sel & SEL_RD)
				sock->flags |= SOCK_FLG_SEL_READ;
			if (sel & SEL_WR)
				sock->flags |= SOCK_FLG_SEL_WRITE;
			/* FIXME we do not monitor error */
		}
		send_reply(m, 0);
		return;
	}

	if (sel & SEL_RD) {
		if (sock->recv_head)
			retsel |= SEL_RD;
		else if (sel & SEL_NOTIFY)
			sock->flags |= SOCK_FLG_SEL_READ;
	}
	/* FIXME generic packet socket never blocks on write */
	if (sel & SEL_WR)
		retsel |= SEL_WR;
	/* FIXME SEL_ERR is ignored, we do not generate exceptions */

	send_reply(m, retsel);
}

void generic_op_select_reply(struct socket * sock, __unused message * m)
{
	assert(sock->select_ep != NONE);
	debug_print("socket num %ld", get_sock_num(sock));

	/* unused for generic packet socket, see generic_op_select() */
	assert((sock->flags & (SOCK_FLG_SEL_WRITE | SOCK_FLG_SEL_ERROR)) == 0);

	if (sock->flags & (SOCK_FLG_OP_PENDING | SOCK_FLG_OP_REVIVING)) {
		debug_print("WARNING socket still blocking!");
		return;
	}

	if (sock->flags & SOCK_FLG_SEL_READ && sock->recv_head)
		m->DEV_SEL_OPS |= SEL_RD;
	
	if (m->DEV_SEL_OPS) 
		sock->flags &= ~(SOCK_FLG_SEL_WRITE | SOCK_FLG_SEL_READ |
							SOCK_FLG_SEL_ERROR);
}