/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2004, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id: hostthre.c,v 1.14 2004/10/16 12:59:05 giva Exp $
 ***************************************************************************/

#include "setup.h"

#include <string.h>
#include <errno.h>

#define _REENTRANT

#if defined( WIN32 ) && !defined( __GNUC__ ) || defined( __MINGW32__ )
#include <malloc.h>
#else
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_STDLIB_H
#include <stdlib.h>     /* required for free() prototypes */
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>     /* for the close() proto */
#endif
#ifdef  VMS
#include <in.h>
#include <inet.h>
#include <stdlib.h>
#endif
#endif

#ifdef HAVE_SETJMP_H
#include <setjmp.h>
#endif

#ifdef WIN32
#include <stdlib.h>
#include <process.h>
#endif

#if ( defined( NETWARE ) && defined( __NOVELL_LIBC__ ) )
#undef in_addr_t
#define in_addr_t unsigned long
#endif

#include "urldata.h"
#include "sendf.h"
#include "hostip.h"
#include "hash.h"
#include "share.h"
#include "strerror.h"
#include "url.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

#include "inet_ntop.h"

#include "memory.h"
/* The last #include file should be: */
#include "memdebug.h"

/***********************************************************************
 * Only for Windows threaded name resolves builds
 **********************************************************************/
#ifdef CURLRES_THREADED

/* This function is used to init a threaded resolve */
static bool init_resolve_thread( struct connectdata *conn,
								 const char *hostname, int port,
								 const Curl_addrinfo *hints );

#ifdef CURLRES_IPV4
  #define THREAD_FUNC  gethostbyname_thread
  #define THREAD_NAME "gethostbyname_thread"
#else
  #define THREAD_FUNC  getaddrinfo_thread
  #define THREAD_NAME "getaddrinfo_thread"
#endif

#if defined( DEBUG_THREADING_GETHOSTBYNAME ) ||	\
	defined( DEBUG_THREADING_GETADDRINFO )
/* If this is defined, provide tracing */
#define TRACE( args )  \
	do { trace_it( "%u: ", __LINE__ ); trace_it args; } while ( 0 )

static void trace_it( const char *fmt, ... ) {
	static int do_trace = -1;
	va_list args;

	if ( do_trace == -1 ) {
		const char *env = getenv( "CURL_TRACE" );
		do_trace = ( env && atoi( env ) > 0 );
	}
	if ( !do_trace ) {
		return;
	}
	va_start( args, fmt );
	vfprintf( stderr, fmt, args );
	fflush( stderr );
	va_end( args );
}
#else
#define TRACE( x )
#endif

#ifdef DEBUG_THREADING_GETADDRINFO
static void dump_addrinfo( struct connectdata *conn, const struct addrinfo *ai ) {
	TRACE( ( "dump_addrinfo:\n" ) );
	for ( ; ai; ai = ai->ai_next ) {
		char buf [INET6_ADDRSTRLEN];

		trace_it( "    fam %2d, CNAME %s, ",
				  ai->ai_family, ai->ai_canonname ? ai->ai_canonname : "<none>" );
		if ( Curl_printable_address( ai, buf, sizeof( buf ) ) ) {
			trace_it( "%s\n", buf );
		} else {
			trace_it( "failed; %s\n", Curl_strerror( conn,WSAGetLastError() ) );
		}
	}
}
#endif

struct thread_data {
	HANDLE thread_hnd;
	unsigned thread_id;
	DWORD thread_status;
	curl_socket_t dummy_sock; /* dummy for Curl_fdset() */
	FILE *stderr_file;
	HANDLE mutex_waiting; /* marks that we are still waiting for a resolve */
	HANDLE event_resolved; /* marks that the thread obtained the information */
#ifdef CURLRES_IPV6
	struct addrinfo hints;
#endif
};

#if defined( CURLRES_IPV4 )
/*
 * gethostbyname_thread() resolves a name, calls the Curl_addrinfo4_callback
 * and then exits.
 *
 * For builds without ARES/ENABLE_IPV6, create a resolver thread and wait on
 * it.
 */
static unsigned __stdcall gethostbyname_thread( void *arg ) {
	struct connectdata *conn = (struct connectdata*) arg;
	struct thread_data *td = (struct thread_data*) conn->async.os_specific;
	struct hostent *he;
	int rc = 0;

	/* Duplicate the passed mutex handle.
	 * This allows us to use it even after the container gets destroyed
	 * due to a resolver timeout.
	 */
	HANDLE mutex_waiting = NULL;
	if ( !DuplicateHandle( GetCurrentProcess(), td->mutex_waiting,
						   GetCurrentProcess(), &mutex_waiting, 0, FALSE,
						   DUPLICATE_SAME_ACCESS ) ) {
		/* failed to duplicate the mutex, no point in continuing */
		return 0;
	}

	/* Sharing the same _iob[] element with our parent thread should
	 * hopefully make printouts synchronised. I'm not sure it works
	 * with a static runtime lib (MSVC's libc.lib).
	 */
	*stderr = *td->stderr_file;

	WSASetLastError( conn->async.status = NO_DATA ); /* pending status */
	he = gethostbyname( conn->async.hostname );

	/* is the thread initiator still waiting for us ? */
	if ( WaitForSingleObject( mutex_waiting, 0 ) == WAIT_TIMEOUT ) {
		/* yes, it is */

		/* Mark that we have obtained the information, and that we are
		 * calling back with it.
		 */
		SetEvent( td->event_resolved );

		if ( he ) {
			Curl_addrinfo4_callback( conn, CURL_ASYNC_SUCCESS, he );
			rc = 1;
		} else {
			Curl_addrinfo4_callback( conn, (int)WSAGetLastError(), NULL );
			rc = 0;
		}
		TRACE( ( "Winsock-error %d, addr %s\n", conn->async.status,
				 he ? inet_ntoa( *(struct in_addr*)he->h_addr ) : "unknown" ) );
	}

	/* clean up */
	CloseHandle( mutex_waiting );

	return ( rc );
	/* An implicit _endthreadex() here */
}

#elif defined( CURLRES_IPV6 )

/*
 * getaddrinfo_thread() resolves a name, calls Curl_addrinfo6_callback and then
 * exits.
 *
 * For builds without ARES, but with ENABLE_IPV6, create a resolver thread
 * and wait on it.
 */
static unsigned __stdcall getaddrinfo_thread( void *arg ) {
	struct connectdata *conn = (struct connectdata*) arg;
	struct thread_data *td   = (struct thread_data*) conn->async.os_specific;
	struct addrinfo    *res;
	char service [NI_MAXSERV];
	int rc;

	/* Duplicate the passed mutex handle.
	 * This allows us to use it even after the container gets destroyed
	 * due to a resolver timeout.
	 */
	HANDLE mutex_waiting = NULL;
	if ( !DuplicateHandle( GetCurrentProcess(), td->mutex_waiting,
						   GetCurrentProcess(), &mutex_waiting, 0, FALSE,
						   DUPLICATE_SAME_ACCESS ) ) {
		/* failed to duplicate the mutex, no point in continuing */
		return 0;
	}

	*stderr = *td->stderr_file;

	itoa( conn->async.port, service, 10 );

	WSASetLastError( conn->async.status = NO_DATA ); /* pending status */

	rc = getaddrinfo( conn->async.hostname, service, &td->hints, &res );

	/* is the thread initiator still waiting for us ? */
	if ( WaitForSingleObject( mutex_waiting, 0 ) == WAIT_TIMEOUT ) {
		/* yes, it is */

		/* Mark that we have obtained the information, and that we are
		 * calling back with it.
		 */
		SetEvent( td->event_resolved );

		if ( rc == 0 ) {
#ifdef DEBUG_THREADING_GETADDRINFO
			dump_addrinfo( conn, res );
#endif
			Curl_addrinfo6_callback( conn, CURL_ASYNC_SUCCESS, res );
		} else {
			Curl_addrinfo6_callback( conn, (int)WSAGetLastError(), NULL );
			TRACE( ( "Winsock-error %d, no address\n", conn->async.status ) );
		}
	}

	/* clean up */
	CloseHandle( mutex_waiting );

	return ( rc );
	/* An implicit _endthreadex() here */
}
#endif

/*
 * destroy_thread_data() cleans up async resolver data.
 * Complementary of ares_destroy.
 */
static void destroy_thread_data( struct Curl_async *async ) {
	if ( async->hostname ) {
		free( async->hostname );
	}

	if ( async->os_specific ) {
		struct thread_data *td = (struct thread_data*) async->os_specific;
		curl_socket_t sock = td->dummy_sock;

		if ( sock != CURL_SOCKET_BAD ) {
			sclose( sock );
		}

		/* destroy the synchronization objects */
		if ( td->mutex_waiting ) {
			CloseHandle( td->mutex_waiting );
		}
		if ( td->event_resolved ) {
			CloseHandle( td->event_resolved );
		}

		free( async->os_specific );
	}
	async->hostname = NULL;
	async->os_specific = NULL;
}

/*
 * init_resolve_thread() starts a new thread that performs the actual
 * resolve. This function returns before the resolve is done.
 *
 * Returns FALSE in case of failure, otherwise TRUE.
 */
static bool init_resolve_thread( struct connectdata *conn,
								 const char *hostname, int port,
								 const Curl_addrinfo *hints ) {
	struct thread_data *td = calloc( sizeof( *td ), 1 );

	if ( !td ) {
		SetLastError( ENOMEM );
		return FALSE;
	}

	Curl_safefree( conn->async.hostname );
	conn->async.hostname = strdup( hostname );
	if ( !conn->async.hostname ) {
		free( td );
		SetLastError( ENOMEM );
		return FALSE;
	}

	conn->async.port = port;
	conn->async.done = FALSE;
	conn->async.status = 0;
	conn->async.dns = NULL;
	conn->async.os_specific = (void*) td;
	td->dummy_sock = CURL_SOCKET_BAD;

	/* Create the mutex used to inform the resolver thread that we're
	 * still waiting, and take initial ownership.
	 */
	td->mutex_waiting = CreateMutex( NULL, TRUE, NULL );
	if ( td->mutex_waiting == NULL ) {
		destroy_thread_data( &conn->async );
		SetLastError( EAGAIN );
		return FALSE;
	}

	/* Create the event that the thread uses to inform us that it's
	 * done resolving. Do not signal it.
	 */
	td->event_resolved = CreateEvent( NULL, TRUE, FALSE, NULL );
	if ( td->event_resolved == NULL ) {
		destroy_thread_data( &conn->async );
		SetLastError( EAGAIN );
		return FALSE;
	}

	td->stderr_file = stderr;
	td->thread_hnd = (HANDLE) _beginthreadex( NULL, 0, THREAD_FUNC,
											  conn, 0, &td->thread_id );
#ifdef CURLRES_IPV6
	curlassert( hints );
	td->hints = *hints;
#else
	(void) hints;
#endif

	if ( !td->thread_hnd ) {
		SetLastError( errno );
		TRACE( ( "_beginthreadex() failed; %s\n", Curl_strerror( conn,errno ) ) );
		destroy_thread_data( &conn->async );
		return FALSE;
	}
	/* This socket is only to keep Curl_fdset() and select() happy; should never
	 * become signalled for read/write since it's unbound but Windows needs
	 * atleast 1 socket in select().
	 */
	td->dummy_sock = socket( AF_INET, SOCK_DGRAM, 0 );
	return TRUE;
}


/*
 * Curl_wait_for_resolv() waits for a resolve to finish. This function should
 * be avoided since using this risk getting the multi interface to "hang".
 *
 * If 'entry' is non-NULL, make it point to the resolved dns entry
 *
 * This is the version for resolves-in-a-thread.
 */
CURLcode Curl_wait_for_resolv( struct connectdata *conn,
							   struct Curl_dns_entry **entry ) {
	struct thread_data   *td = (struct thread_data*) conn->async.os_specific;
	struct SessionHandle *data = conn->data;
	long timeout;
	DWORD status, ticks;
	CURLcode rc;

	curlassert( conn && td );

	/* now, see if there's a connect timeout or a regular timeout to
	   use instead of the default one */
	timeout =
		conn->data->set.connecttimeout ? conn->data->set.connecttimeout :
		conn->data->set.timeout ? conn->data->set.timeout :
		CURL_TIMEOUT_RESOLVE; /* default name resolve timeout */
	ticks = GetTickCount();

	/* wait for the thread to resolve the name */
	status = WaitForSingleObject( td->event_resolved, 1000UL * timeout );

	/* mark that we are now done waiting */
	ReleaseMutex( td->mutex_waiting );

	/* close our handle to the mutex, no point in hanging on to it */
	CloseHandle( td->mutex_waiting );
	td->mutex_waiting = NULL;

	/* close the event handle, it's useless now */
	CloseHandle( td->event_resolved );
	td->event_resolved = NULL;

	/* has the resolver thread succeeded in resolving our query ? */
	if ( status == WAIT_OBJECT_0 ) {
		/* wait for the thread to exit, it's in the callback sequence */
		if ( WaitForSingleObject( td->thread_hnd, 5000 ) == WAIT_TIMEOUT ) {
			TerminateThread( td->thread_hnd, 0 );
			conn->async.done = TRUE;
			td->thread_status = (DWORD)-1;
			TRACE( ( "%s() thread stuck?!, ", THREAD_NAME ) );
		} else {
			/* Thread finished before timeout; propagate Winsock error to this thread.
			 * 'conn->async.done = TRUE' is set in Curl_addrinfo4/6_callback().
			 */
			WSASetLastError( conn->async.status );
			GetExitCodeThread( td->thread_hnd, &td->thread_status );
			TRACE( ( "%s() status %lu, thread retval %lu, ",
					 THREAD_NAME, status, td->thread_status ) );
		}
	} else {
		conn->async.done = TRUE;
		td->thread_status = (DWORD)-1;
		TRACE( ( "%s() timeout, ", THREAD_NAME ) );
	}

	TRACE( ( "elapsed %lu ms\n", GetTickCount() - ticks ) );

	CloseHandle( td->thread_hnd );

	if ( entry ) {
		*entry = conn->async.dns;
	}

	rc = CURLE_OK;

	if ( !conn->async.dns ) {
		/* a name was not resolved */
		if ( td->thread_status == (DWORD)-1 || conn->async.status == NO_DATA ) {
			failf( data, "Resolving host timed out: %s", conn->host.name );
			rc = CURLE_OPERATION_TIMEDOUT;
		} else if ( conn->async.done )      {
			failf( data, "Could not resolve host: %s; %s",
				   conn->host.name, Curl_strerror( conn,conn->async.status ) );
			rc = CURLE_COULDNT_RESOLVE_HOST;
		} else {
			rc = CURLE_OPERATION_TIMEDOUT;
		}
	}

	destroy_thread_data( &conn->async );

	if ( CURLE_OK != rc ) {
		/* close the connection, since we must not return failure from here
		   without cleaning up this connection properly */
		Curl_disconnect( conn );
	}

	return ( rc );
}

/*
 * Curl_is_resolved() is called repeatedly to check if a previous name resolve
 * request has completed. It should also make sure to time-out if the
 * operation seems to take too long.
 */
CURLcode Curl_is_resolved( struct connectdata *conn,
						   struct Curl_dns_entry **entry ) {
	*entry = NULL;

	if ( conn->async.done ) {
		/* we're done */
		destroy_thread_data( &conn->async );
		if ( !conn->async.dns ) {
			TRACE( ( "Curl_is_resolved(): CURLE_COULDNT_RESOLVE_HOST\n" ) );
			return CURLE_COULDNT_RESOLVE_HOST;
		}
		*entry = conn->async.dns;
		TRACE( ( "resolved okay, dns %p\n", *entry ) );
	} else {
		TRACE( ( "not yet\n" ) );
	}
	return CURLE_OK;
}

CURLcode Curl_fdset( struct connectdata *conn,
					 fd_set *read_fd_set,
					 fd_set *write_fd_set,
					 int *max_fdp ) {
	const struct thread_data *td =
		(const struct thread_data *) conn->async.os_specific;

	if ( td && td->dummy_sock != CURL_SOCKET_BAD ) {
		FD_SET( td->dummy_sock,write_fd_set );
		*max_fdp = td->dummy_sock;
	}
	(void) read_fd_set;
	return CURLE_OK;
}

#ifdef CURLRES_IPV4
/*
 * Curl_getaddrinfo() - for Windows threading without ENABLE_IPV6.
 */
Curl_addrinfo *Curl_getaddrinfo( struct connectdata *conn,
								 char *hostname,
								 int port,
								 int *waitp ) {
	struct hostent *h = NULL;
	struct SessionHandle *data = conn->data;
	in_addr_t in;

	*waitp = 0; /* don't wait, we act synchronously */

	in = inet_addr( hostname );
	if ( in != CURL_INADDR_NONE ) {
		/* This is a dotted IP address 123.123.123.123-style */
		return Curl_ip2addr( in, hostname, port );
	}

	/* fire up a new resolver thread! */
	if ( init_resolve_thread( conn, hostname, port, NULL ) ) {
		*waitp = TRUE; /* please wait for the response */
		return NULL;
	}

	/* fall-back to blocking version */
	infof( data, "init_resolve_thread() failed for %s; %s\n",
		   hostname, Curl_strerror( conn,GetLastError() ) );

	h = gethostbyname( hostname );
	if ( !h ) {
		infof( data, "gethostbyname(2) failed for %s:%d; %s\n",
			   hostname, port, Curl_strerror( conn,WSAGetLastError() ) );
		return NULL;
	}
	return Curl_he2ai( h, port );
}
#endif /* CURLRES_IPV4 */

#ifdef CURLRES_IPV6
/*
 * Curl_getaddrinfo() - for Windows threading IPv6 enabled
 */
Curl_addrinfo *Curl_getaddrinfo( struct connectdata *conn,
								 char *hostname,
								 int port,
								 int *waitp ) {
	struct addrinfo hints, *res;
	int error;
	char sbuf[NI_MAXSERV];
	curl_socket_t s;
	int pf;
	struct SessionHandle *data = conn->data;

	*waitp = FALSE; /* default to synch response */

	/* see if we have an IPv6 stack */
	s = socket( PF_INET6, SOCK_DGRAM, 0 );
	if ( s == CURL_SOCKET_BAD ) {
		/* Some non-IPv6 stacks have been found to make very slow name resolves
		 * when PF_UNSPEC is used, so thus we switch to a mere PF_INET lookup if
		 * the stack seems to be a non-ipv6 one. */

		pf = PF_INET;
	} else {
		/* This seems to be an IPv6-capable stack, use PF_UNSPEC for the widest
		 * possible checks. And close the socket again.
		 */
		sclose( s );

		/*
		 * Check if a more limited name resolve has been requested.
		 */
		switch ( data->set.ip_version ) {
		case CURL_IPRESOLVE_V4:
			pf = PF_INET;
			break;
		case CURL_IPRESOLVE_V6:
			pf = PF_INET6;
			break;
		default:
			pf = PF_UNSPEC;
			break;
		}
	}

	memset( &hints, 0, sizeof( hints ) );
	hints.ai_family = pf;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_CANONNAME;
	itoa( port, sbuf, 10 );

	/* fire up a new resolver thread! */
	if ( init_resolve_thread( conn, hostname, port, &hints ) ) {
		*waitp = TRUE; /* please wait for the response */
		return NULL;
	}

	/* fall-back to blocking version */
	infof( data, "init_resolve_thread() failed for %s; %s\n",
		   hostname, Curl_strerror( conn,GetLastError() ) );

	error = getaddrinfo( hostname, sbuf, &hints, &res );
	if ( error ) {
		infof( data, "getaddrinfo() failed for %s:%d; %s\n",
			   hostname, port, Curl_strerror( conn,WSAGetLastError() ) );
		return NULL;
	}
	return res;
}
#endif /* CURLRES_IPV6 */
#endif /* CURLRES_THREADED */
