/*
 * Copyright (c) 2013 Joris Vink <joris@coders.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <sys/epoll.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <openssl/err.h>
#include <openssl/ssl.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "spdy.h"
#include "kore.h"

#define EPOLL_EVENTS	500

static int	efd = -1;
static SSL_CTX	*ssl_ctx = NULL;

static int	kore_socket_nonblock(int);
static int	kore_server_sslstart(void);
static void	kore_event(int, int, void *);
static int	kore_server_accept(struct listener *);
static void	kore_server_disconnect(struct connection *);
static int	kore_connection_handle(struct connection *, int);
static int	kore_server_bind(struct listener *, const char *, int);
static int	kore_ssl_npn_cb(SSL *, const u_char **, unsigned int *, void *);

int
main(int argc, char *argv[])
{
	struct connection	*c;
	struct listener		server;
	struct epoll_event	*events;
	int			n, i, *fd;

	if (argc != 3)
		fatal("Usage: kore [ip] [port]");

	if (!kore_server_bind(&server, argv[1], atoi(argv[2])))
		fatal("cannot bind to %s:%s", argv[1], argv[2]);
	if (!kore_server_sslstart())
		fatal("cannot initiate SSL");

	if ((efd = epoll_create(1000)) == -1)
		fatal("epoll_create(): %s", errno_s);

	kore_event(server.fd, EPOLLIN, &server);
	events = kore_calloc(EPOLL_EVENTS, sizeof(struct epoll_event));
	for (;;) {
		kore_log("main(): epoll_wait()");
		n = epoll_wait(efd, events, EPOLL_EVENTS, -1);
		if (n == -1)
			fatal("epoll_wait(): %s", errno_s);

		kore_log("main(): %d sockets available", n);
		for (i = 0; i < n; i++) {
			fd = (int *)events[i].data.ptr;

			if (events[i].events & EPOLLERR ||
			    events[i].events & EPOLLHUP) {
				if (*fd == server.fd)
					fatal("error on server socket");

				c = (struct connection *)events[i].data.ptr;
				kore_server_disconnect(c);
				continue;
			}

			if (*fd == server.fd) {
				kore_server_accept(&server);
			} else {
				c = (struct connection *)events[i].data.ptr;
				if (!kore_connection_handle(c,
				    events[i].events))
					kore_server_disconnect(c);
			}
		}
	}

	close(server.fd);
	return (0);
}

static int
kore_server_sslstart(void)
{
	kore_log("kore_server_sslstart()");

	SSL_library_init();
	SSL_load_error_strings();
	ssl_ctx = SSL_CTX_new(SSLv23_server_method());
	if (ssl_ctx == NULL) {
		kore_log("SSL_ctx_new(): %s", ssl_errno_s);
		return (KORE_RESULT_ERROR);
	}

	if (!SSL_CTX_use_certificate_file(ssl_ctx, "cert/server.crt",
	    SSL_FILETYPE_PEM)) {
		kore_log("SSL_CTX_use_certificate_file(): %s", ssl_errno_s);
		return (KORE_RESULT_ERROR);
	}

	if (!SSL_CTX_use_PrivateKey_file(ssl_ctx, "cert/server.key",
	    SSL_FILETYPE_PEM)) {
		kore_log("SSL_CTX_use_PrivateKey_file(): %s", ssl_errno_s);
		return (KORE_RESULT_ERROR);
	}

	SSL_CTX_set_mode(ssl_ctx, SSL_MODE_AUTO_RETRY);
	SSL_CTX_set_mode(ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
	SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv2);
	SSL_CTX_set_next_protos_advertised_cb(ssl_ctx, kore_ssl_npn_cb, NULL);

	return (KORE_RESULT_OK);
}

static int
kore_server_bind(struct listener *l, const char *ip, int port)
{
	kore_log("kore_server_bind(%p, %s, %d)", l, ip, port);

	if ((l->fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
		kore_log("socket(): %s", errno_s);
		return (KORE_RESULT_ERROR);
	}

	if (!kore_socket_nonblock(l->fd)) {
		close(l->fd);
		return (KORE_RESULT_ERROR);
	}

	memset(&(l->sin), 0, sizeof(l->sin));
	l->sin.sin_family = AF_INET;
	l->sin.sin_port = htons(port);
	l->sin.sin_addr.s_addr = inet_addr(ip);

	if (bind(l->fd, (struct sockaddr *)&(l->sin), sizeof(l->sin)) == -1) {
		close(l->fd);
		kore_log("bind(): %s", errno_s);
		return (KORE_RESULT_ERROR);
	}

	if (listen(l->fd, 50) == -1) {
		close(l->fd);
		kore_log("listen(): %s", errno_s);
		return (KORE_RESULT_ERROR);
	}

	return (KORE_RESULT_OK);
}

static int
kore_server_accept(struct listener *l)
{
	socklen_t		len;
	struct connection	*c;

	kore_log("kore_server_accept(%p)", l);

	len = sizeof(struct sockaddr_in);
	c = (struct connection *)kore_malloc(sizeof(*c));
	if ((c->fd = accept(l->fd, (struct sockaddr *)&(c->sin), &len)) == -1) {
		free(c);
		kore_log("accept(): %s", errno_s);
		return (KORE_RESULT_ERROR);
	}

	if (!kore_socket_nonblock(c->fd)) {
		close(c->fd);
		free(c);
		return (KORE_RESULT_ERROR);
	}

	c->owner = l;
	c->ssl = NULL;
	c->proto = CONN_PROTO_UNKNOWN;
	c->state = CONN_STATE_SSL_SHAKE;

	TAILQ_INIT(&(c->send_queue));
	TAILQ_INIT(&(c->recv_queue));
	TAILQ_INIT(&(c->spdy_streams));;
	kore_event(c->fd, EPOLLIN | EPOLLET, c);
	kore_log("new connection from %s", inet_ntoa(c->sin.sin_addr));

	return (KORE_RESULT_OK);
}

static void
kore_server_disconnect(struct connection *c)
{
	struct netbuf		*nb, *next;

	kore_log("kore_server_disconnect(%p)", c);

	close(c->fd);
	if (c->ssl != NULL)
		SSL_free(c->ssl);

	for (nb = TAILQ_FIRST(&(c->send_queue)); nb != NULL; nb = next) {
		next = TAILQ_NEXT(nb, list);
		TAILQ_REMOVE(&(c->send_queue), nb, list);
		free(nb->buf);
		free(nb);
	}

	for (nb = TAILQ_FIRST(&(c->recv_queue)); nb != NULL; nb = next) {
		next = TAILQ_NEXT(nb, list);
		TAILQ_REMOVE(&(c->recv_queue), nb, list);
		free(nb->buf);
		free(nb);
	}

	kore_log("disconnect connection from %s", inet_ntoa(c->sin.sin_addr));
	free(c);
}

static int
kore_connection_handle(struct connection *c, int flags)
{
	int			r;
	u_int32_t		len;
	const u_char		*data;

	kore_log("kore_connection_handle(%p, %d)", c, flags);

	switch (c->state) {
	case CONN_STATE_SSL_SHAKE:
		if (c->ssl == NULL) {
			c->ssl = SSL_new(ssl_ctx);
			if (c->ssl == NULL) {
				kore_log("SSL_new(): %s", ssl_errno_s);
				return (KORE_RESULT_ERROR);
			}

			SSL_set_fd(c->ssl, c->fd);
		}

		r = SSL_accept(c->ssl);
		if (r <= 0) {
			r = SSL_get_error(c->ssl, r);
			switch (r) {
			case SSL_ERROR_WANT_READ:
				kore_log("ssl_want_read on handshake");
				return (KORE_RESULT_OK);
			case SSL_ERROR_WANT_WRITE:
				kore_log("ssl_want_write on handshake");
				return (KORE_RESULT_OK);
			default:
				kore_log("SSL_accept(): %s", ssl_errno_s);
				return (KORE_RESULT_ERROR);
			}
		}

		r = SSL_get_verify_result(c->ssl);
		if (r != X509_V_OK) {
			kore_log("SSL_get_verify_result(): %s", ssl_errno_s);
			return (KORE_RESULT_ERROR);
		}

		SSL_get0_next_proto_negotiated(c->ssl, &data, &len);
		if (data) {
			if (!memcmp(data, "spdy/3", 6))
				kore_log("using SPDY/3");
			c->proto = CONN_PROTO_SPDY;
			if (!net_recv_queue(c,
			    SPDY_FRAME_SIZE, spdy_frame_recv))
				return (KORE_RESULT_ERROR);
		} else {
			kore_log("using HTTP/1.1");
			c->proto = CONN_PROTO_HTTP;
		}

		c->state = CONN_STATE_ESTABLISHED;
		break;
	case CONN_STATE_ESTABLISHED:
		if (flags & EPOLLIN) {
			if (!net_recv(c))
				return (KORE_RESULT_ERROR);
		} else {
			kore_log("got unhandled client event");
		}
		break;
	default:
		kore_log("unknown state on %d (%d)", c->fd, c->state);
		break;
	}

	return (KORE_RESULT_OK);
}

static int
kore_socket_nonblock(int fd)
{
	int		flags;

	kore_log("kore_socket_nonblock(%d)", fd);

	if ((flags = fcntl(fd, F_GETFL, 0)) == -1) {
		kore_log("fcntl(): F_GETFL %s", errno_s);
		return (KORE_RESULT_ERROR);
	}

	flags |= O_NONBLOCK;
	if (fcntl(fd, F_SETFL, flags) == -1) {
		kore_log("fcntl(): F_SETFL %s", errno_s);
		return (KORE_RESULT_ERROR);
	}

	return (KORE_RESULT_OK);
}

static int
kore_ssl_npn_cb(SSL *ssl, const u_char **data, unsigned int *len, void *arg)
{
	kore_log("kore_ssl_npn_cb(): sending protocols");

	*data = (const unsigned char *)KORE_SSL_PROTO_STRING;
	*len = strlen(KORE_SSL_PROTO_STRING);

	return (SSL_TLSEXT_ERR_OK);
}

static void
kore_event(int fd, int flags, void *udata)
{
	struct epoll_event	evt;

	kore_log("kore_event(%d, %d, %p)", fd, flags, udata);

	evt.events = flags;
	evt.data.ptr = udata;
	if (epoll_ctl(efd, EPOLL_CTL_ADD, fd, &evt) == -1) {
		if (errno == EEXIST) {
			if (epoll_ctl(efd, EPOLL_CTL_MOD, fd, &evt) == -1)
				fatal("epoll_ctl() MOD: %s", errno_s);
		} else {
			fatal("epoll_ctl() ADD: %s", errno_s);
		}
	}
}