/* We do not modify RSTRING in this file, so RSTRING_MODIFIED is not needed */
#include "kgio.h"
#include "my_fileno.h"
#include "sock_for_fd.h"
#include "blocking_io_region.h"

static void close_fail(int fd, const char *msg)
{
	int saved_errno = errno;
	(void)close(fd);
	errno = saved_errno;
	rb_sys_fail(msg);
}

static int MY_SOCK_STREAM =
#if defined(SOCK_NONBLOCK) && defined(SOCK_CLOEXEC)
#  ifdef HAVE_RB_FD_FIX_CLOEXEC
  (SOCK_STREAM|SOCK_NONBLOCK|SOCK_CLOEXEC)
#  else
  (SOCK_STREAM|SOCK_NONBLOCK)
#  endif
#else
  SOCK_STREAM
#endif /* ! SOCK_NONBLOCK */
;

/* do not set close-on-exec by default on Ruby <2.0.0 */
#ifndef HAVE_RB_FD_FIX_CLOEXEC
#  define rb_fd_fix_cloexec(fd) for (;0;)
#endif /* HAVE_RB_FD_FIX_CLOEXEC */

/* try to use SOCK_NONBLOCK and SOCK_CLOEXEC */
static int my_socket(int domain)
{
	int fd;

retry:
	fd = socket(domain, MY_SOCK_STREAM, 0);

	if (fd < 0) {
		switch (errno) {
		case EMFILE:
		case ENFILE:
#ifdef ENOBUFS
		case ENOBUFS:
#endif /* ENOBUFS */
			errno = 0;
			rb_gc();
			fd = socket(domain, MY_SOCK_STREAM, 0);
			break;
		case EINVAL:
			if (MY_SOCK_STREAM != SOCK_STREAM) {
				MY_SOCK_STREAM = SOCK_STREAM;
				goto retry;
			}
		}
		if (fd < 0)
			rb_sys_fail("socket");
	}

	if (MY_SOCK_STREAM == SOCK_STREAM) {
		if (fcntl(fd, F_SETFL, O_RDWR | O_NONBLOCK) < 0)
			close_fail(fd, "fcntl(F_SETFL, O_RDWR | O_NONBLOCK)");
		rb_fd_fix_cloexec(fd);
	}

	return fd;
}

static VALUE
my_connect(VALUE klass, int io_wait, int domain,
	const void *addr, socklen_t addrlen)
{
	int fd = my_socket(domain);

	if (connect(fd, addr, addrlen) < 0) {
		if (errno == EINPROGRESS) {
			VALUE io = sock_for_fd(klass, fd);

			if (io_wait) {
				errno = EAGAIN;
				(void)kgio_call_wait_writable(io);
			}
			return io;
		}
		close_fail(fd, "connect");
	}
	return sock_for_fd(klass, fd);
}

static void
tcp_getaddr(struct addrinfo *hints, struct sockaddr_storage *addr,
             VALUE ip, VALUE port)
{
	int rc;
	struct addrinfo *res;
	const char *ipname = StringValuePtr(ip);
	char ipport[6];
	unsigned uport;

	if (TYPE(port) != T_FIXNUM)
		rb_raise(rb_eTypeError, "port must be a non-negative integer");
	uport = FIX2UINT(port);

	rc = snprintf(ipport, sizeof(ipport), "%u", uport);
	if (rc >= (int)sizeof(ipport) || rc <= 0)
		rb_raise(rb_eArgError, "invalid TCP port: %u", uport);
	memset(hints, 0, sizeof(struct addrinfo));
	hints->ai_family = AF_UNSPEC;
	hints->ai_socktype = SOCK_STREAM;
	hints->ai_protocol = IPPROTO_TCP;
	/* disallow non-deterministic DNS lookups */
	hints->ai_flags = AI_NUMERICHOST;

	rc = getaddrinfo(ipname, ipport, hints, &res);
	if (rc != 0)
		rb_raise(rb_eArgError, "getaddrinfo(%s:%s): %s",
			 ipname, ipport, gai_strerror(rc));

	/* copy needed data and free ASAP to avoid needing rb_ensure */
	hints->ai_family = res->ai_family;
	hints->ai_addrlen = res->ai_addrlen;
	memcpy(addr, res->ai_addr, res->ai_addrlen);
	freeaddrinfo(res);
}

static VALUE tcp_connect(VALUE klass, VALUE ip, VALUE port, int io_wait)
{
	struct addrinfo hints;
	struct sockaddr_storage addr;

	tcp_getaddr(&hints, &addr, ip, port);

	return my_connect(klass, io_wait, hints.ai_family,
	                  &addr, hints.ai_addrlen);
}

static const struct sockaddr *sockaddr_from(socklen_t *addrlen, VALUE addr)
{
	if (TYPE(addr) == T_STRING) {
		*addrlen = (socklen_t)RSTRING_LEN(addr);
		return (const struct sockaddr *)(RSTRING_PTR(addr));
	}
	rb_raise(rb_eTypeError, "invalid address");
	return NULL;
}

#if defined(MSG_FASTOPEN) && defined(KGIO_WITHOUT_GVL)
struct tfo_args {
	int fd;
	const void *buf;
	size_t buflen;
	const struct sockaddr *addr;
	socklen_t addrlen;
};

static VALUE tfo_sendto(void *_a)
{
	struct tfo_args *a = _a;
	ssize_t w;

	w = sendto(a->fd, a->buf, a->buflen, MSG_FASTOPEN, a->addr, a->addrlen);
	return (VALUE)w;
}

/*
 * call-seq:
 *
 *	s = Kgio::Socket.new(:INET, :STREAM)
 *	addr = Socket.pack_sockaddr_in(80, "example.com")
 *	s.kgio_fastopen("hello world", addr) -> nil
 *
 * Starts a TCP connection using TCP Fast Open.  This uses a blocking
 * sendto() syscall and is only available on Ruby 1.9 or later.
 * This raises exceptions (including Errno::EINPROGRESS/Errno::EAGAIN)
 * on errors.  Using this is only recommended for blocking sockets.
 *
 * Timeouts may be set with setsockopt:
 *
 *	s.setsockopt(:SOCKET, :SNDTIMEO, [1,0].pack("l_l_"))
 */
static VALUE fastopen(VALUE sock, VALUE buf, VALUE addr)
{
	struct tfo_args a;
	VALUE str = (TYPE(buf) == T_STRING) ? buf : rb_obj_as_string(buf);
	ssize_t w;

	a.fd = my_fileno(sock);
	a.buf = RSTRING_PTR(str);
	a.buflen = (size_t)RSTRING_LEN(str);
	a.addr = sockaddr_from(&a.addrlen, addr);

	/* n.b. rb_thread_blocking_region preserves errno */
	w = (ssize_t)rb_thread_io_blocking_region(tfo_sendto, &a, a.fd);
	if (w < 0)
		rb_sys_fail("sendto");
	if ((size_t)w == a.buflen)
		return Qnil;

	return MY_STR_SUBSEQ(str, w, a.buflen - w);
}
#endif /* MSG_FASTOPEN */

/*
 * call-seq:
 *
 *	Kgio::TCPSocket.new('127.0.0.1', 80) -> socket
 *
 * Creates a new Kgio::TCPSocket object and initiates a
 * non-blocking connection.
 *
 * This may block and call any method defined to +kgio_wait_writable+
 * for the class.
 *
 * Unlike the TCPSocket.new in Ruby, this does NOT perform DNS
 * lookups (which is subject to a different set of timeouts and
 * best handled elsewhere).
 */
static VALUE kgio_tcp_connect(VALUE klass, VALUE ip, VALUE port)
{
	return tcp_connect(klass, ip, port, 1);
}

/*
 * call-seq:
 *
 *	Kgio::TCPSocket.start('127.0.0.1', 80) -> socket
 *
 * Creates a new Kgio::TCPSocket object and initiates a
 * non-blocking connection.  The caller should select/poll
 * on the socket for writability before attempting to write
 * or optimistically attempt a write and handle :wait_writable
 * or Errno::EAGAIN.
 *
 * Unlike the TCPSocket.new in Ruby, this does NOT perform DNS
 * lookups (which is subject to a different set of timeouts and
 * best handled elsewhere).
 */
static VALUE kgio_tcp_start(VALUE klass, VALUE ip, VALUE port)
{
	return tcp_connect(klass, ip, port, 0);
}

static VALUE unix_connect(VALUE klass, VALUE path, int io_wait)
{
	struct sockaddr_un addr = { 0 };
	long len;

	StringValue(path);
	len = RSTRING_LEN(path);
	if ((long)sizeof(addr.sun_path) <= len)
		rb_raise(rb_eArgError,
		         "too long unix socket path (max: %dbytes)",
		         (int)sizeof(addr.sun_path)-1);

	memcpy(addr.sun_path, RSTRING_PTR(path), len);
	addr.sun_family = AF_UNIX;

	return my_connect(klass, io_wait, PF_UNIX, &addr, sizeof(addr));
}

/*
 * call-seq:
 *
 *	Kgio::UNIXSocket.new("/path/to/unix/socket") -> socket
 *
 * Creates a new Kgio::UNIXSocket object and initiates a
 * non-blocking connection.
 *
 * This may block and call any method defined to +kgio_wait_writable+
 * for the class.
 */
static VALUE kgio_unix_connect(VALUE klass, VALUE path)
{
	return unix_connect(klass, path, 1);
}

/*
 * call-seq:
 *
 *	Kgio::UNIXSocket.start("/path/to/unix/socket") -> socket
 *
 * Creates a new Kgio::UNIXSocket object and initiates a
 * non-blocking connection.  The caller should select/poll
 * on the socket for writability before attempting to write
 * or optimistically attempt a write and handle :wait_writable
 * or Errno::EAGAIN.
 */
static VALUE kgio_unix_start(VALUE klass, VALUE path)
{
	return unix_connect(klass, path, 0);
}

static VALUE stream_connect(VALUE klass, VALUE addr, int io_wait)
{
	int domain;
	socklen_t addrlen;
	const struct sockaddr *sockaddr = sockaddr_from(&addrlen, addr);

	switch (((const struct sockaddr_storage *)(sockaddr))->ss_family) {
	case AF_UNIX: domain = PF_UNIX; break;
	case AF_INET: domain = PF_INET; break;
	case AF_INET6: domain = PF_INET6; break;
	default:
		rb_raise(rb_eArgError, "invalid address family");
	}

	return my_connect(klass, io_wait, domain, sockaddr, addrlen);
}

/* call-seq:
 *
 *      addr = Socket.pack_sockaddr_in(80, 'example.com')
 *	Kgio::Socket.connect(addr) -> socket
 *
 *      addr = Socket.pack_sockaddr_un("/path/to/unix/socket")
 *	Kgio::Socket.connect(addr) -> socket
 *
 * Creates a generic Kgio::Socket object and initiates a
 * non-blocking connection.
 *
 * This may block and call any method defined to +kgio_wait_writable+
 * for the class.
 */
static VALUE kgio_connect(VALUE klass, VALUE addr)
{
	return stream_connect(klass, addr, 1);
}

/*
 * If passed one argument, this is identical to Kgio::Socket.connect.
 * If passed two or three arguments, it uses its superclass method:
 *
 *   Socket.new(domain, socktype [, protocol ])
 */
static VALUE kgio_new(int argc, VALUE *argv, VALUE klass)
{
	if (argc == 1)
		/* backwards compat, the only way for kgio <= 2.7.4 */
		return stream_connect(klass, argv[0], 1);

	return rb_call_super(argc, argv);
}

/* call-seq:
 *
 *      addr = Socket.pack_sockaddr_in(80, 'example.com')
 *	Kgio::Socket.start(addr) -> socket
 *
 *      addr = Socket.pack_sockaddr_un("/path/to/unix/socket")
 *	Kgio::Socket.start(addr) -> socket
 *
 * Creates a generic Kgio::Socket object and initiates a
 * non-blocking connection.  The caller should select/poll
 * on the socket for writability before attempting to write
 * or optimistically attempt a write and handle :wait_writable
 * or Errno::EAGAIN.
 */
static VALUE kgio_start(VALUE klass, VALUE addr)
{
	return stream_connect(klass, addr, 0);
}

void init_kgio_connect(void)
{
	VALUE mKgio = rb_define_module("Kgio");
	VALUE cSocket = rb_const_get(rb_cObject, rb_intern("Socket"));
	VALUE mSocketMethods = rb_const_get(mKgio, rb_intern("SocketMethods"));
	VALUE cKgio_Socket, cTCPSocket, cUNIXSocket;

	/*
	 * Document-class: Kgio::Socket
	 *
	 * A generic socket class with Kgio::SocketMethods included.
	 * This is returned by all Kgio methods that accept(2) a connected
	 * stream socket.
	 */
	cKgio_Socket = rb_define_class_under(mKgio, "Socket", cSocket);
	rb_include_module(cKgio_Socket, mSocketMethods);
	rb_define_singleton_method(cKgio_Socket, "new", kgio_new, -1);
	rb_define_singleton_method(cKgio_Socket, "connect", kgio_connect, 1);
	rb_define_singleton_method(cKgio_Socket, "start", kgio_start, 1);
#if defined(MSG_FASTOPEN) && defined(KGIO_WITHOUT_GVL)
	rb_define_method(cKgio_Socket, "kgio_fastopen", fastopen, 2);
#endif
	/*
	 * Document-class: Kgio::TCPSocket
	 *
	 * Kgio::TCPSocket should be used in place of the plain TCPSocket
	 * when kgio_* methods are needed.
	 */
	cTCPSocket = rb_const_get(rb_cObject, rb_intern("TCPSocket"));
	cTCPSocket = rb_define_class_under(mKgio, "TCPSocket", cTCPSocket);
	rb_include_module(cTCPSocket, mSocketMethods);
	rb_define_singleton_method(cTCPSocket, "new", kgio_tcp_connect, 2);
	rb_define_singleton_method(cTCPSocket, "start", kgio_tcp_start, 2);

	/*
	 * Document-class: Kgio::UNIXSocket
	 *
	 * Kgio::UNIXSocket should be used in place of the plain UNIXSocket
	 * when kgio_* methods are needed.
	 */
	cUNIXSocket = rb_const_get(rb_cObject, rb_intern("UNIXSocket"));
	cUNIXSocket = rb_define_class_under(mKgio, "UNIXSocket", cUNIXSocket);
	rb_include_module(cUNIXSocket, mSocketMethods);
	rb_define_singleton_method(cUNIXSocket, "new", kgio_unix_connect, 1);
	rb_define_singleton_method(cUNIXSocket, "start", kgio_unix_start, 1);
	init_sock_for_fd();
}