source: dcc.c @ fa30fa5

/********************************************************************\
* BitlBee -- An IRC to other IM-networks gateway                     *
*                                                                    *
* Copyright 2007 Uli Meis <a.sporto+bee@gmail.com>                   *
\********************************************************************/

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#define BITLBEE_CORE
#include "bitlbee.h"
#include "ft.h"
#include "dcc.h"
#include <poll.h>
#include <netinet/tcp.h>
#include <regex.h>

/* 
 * Since that might be confusing a note on naming:
 *
 * Generic dcc functions start with 
 *
 *      dcc_
 *
 * ,methods specific to DCC SEND start with
 *
 *      dccs_
 *
 * . Since we can be on both ends of a DCC SEND,
 * functions specific to one end are called
 *
 *      dccs_send and dccs_recv
 *
 * ,respectively.
 */


/* 
 * used to generate a unique local transfer id the user
 * can use to reject/cancel transfers
 */
unsigned int local_transfer_id=1;

/* 
 * just for debugging the nr. of chunks we received from im-protocols and the total data
 */
unsigned int receivedchunks=0, receiveddata=0;

int max_packet_size = 0;

static void dcc_finish( file_transfer_t *file );
static void dcc_close( file_transfer_t *file );
gboolean dccs_send_proto( gpointer data, gint fd, b_input_condition cond );
gboolean dcc_listen( dcc_file_transfer_t *df, struct sockaddr_storage **saddr_ptr );
int dccs_send_request( struct dcc_file_transfer *df, char *user_nick, struct sockaddr_storage *saddr );
gboolean dccs_recv_start( file_transfer_t *ft );
gboolean dccs_recv_proto( gpointer data, gint fd, b_input_condition cond);
gboolean dccs_recv_write_request( file_transfer_t *ft );

/* As defined in ft.h */
file_transfer_t *imcb_file_send_start( struct im_connection *ic, char *handle, char *file_name, size_t file_size )
{
        user_t *u = user_findhandle( ic, handle );
        /* one could handle this more intelligent like imcb_buddy_msg.
         * can't call it directly though cause it does some wrapping.
         * Maybe give imcb_buddy_msg a parameter NO_WRAPPING? */
        if (!u) return NULL;

        return dccs_send_start( ic, u->nick, file_name, file_size );
};

/* As defined in ft.h */
void imcb_file_canceled( file_transfer_t *file, char *reason )
{
        if( file->canceled )
                file->canceled( file, reason );

        dcc_close( file );
}

/* As defined in ft.h */
gboolean imcb_file_recv_start( file_transfer_t *ft )
{
        return dccs_recv_start( ft );
}

dcc_file_transfer_t *dcc_alloc_transfer( char *file_name, size_t file_size, struct im_connection *ic )
{
        file_transfer_t *file = g_new0( file_transfer_t, 1 );
        dcc_file_transfer_t *df = file->priv = g_new0( dcc_file_transfer_t, 1);
        file->file_size = file_size;
        file->file_name = g_strdup( file_name );
        file->local_id = local_transfer_id++;
        df->ic = ic;
        df->ft = file;
        
        return df;
}

/* This is where the sending magic starts... */
file_transfer_t *dccs_send_start( struct im_connection *ic, char *user_nick, char *file_name, size_t file_size )
{
        file_transfer_t *file;
        dcc_file_transfer_t *df;
        struct sockaddr_storage *saddr;

        if( file_size > global.conf->max_filetransfer_size )
                return NULL;
        
        df = dcc_alloc_transfer( file_name, file_size, ic );
        file = df->ft;
        file->write = dccs_send_write;
        file->sending = TRUE;

        /* listen and request */
        if( !dcc_listen( df, &saddr ) ||
            !dccs_send_request( df, user_nick, saddr ) )
                return NULL;

        g_free( saddr );

        /* watch */
        df->watch_in = b_input_add( df->fd, GAIM_INPUT_READ, dccs_send_proto, df );

        df->ic->irc->file_transfers = g_slist_prepend( df->ic->irc->file_transfers, file );

        return file;
}

/* Used pretty much everywhere in the code to abort a transfer */
gboolean dcc_abort( dcc_file_transfer_t *df, char *reason, ... )
{
        file_transfer_t *file = df->ft;
        va_list params;
        va_start( params, reason );
        char *msg = g_strdup_vprintf( reason, params );
        va_end( params );
        
        file->status |= FT_STATUS_CANCELED;
        
        if( file->canceled )
                file->canceled( file, msg );
        else 
                imcb_log( df->ic, "DCC transfer aborted: %s", msg );

        g_free( msg );

        dcc_close( df->ft );

        return FALSE;
}

/* used extensively for socket operations */
#define ASSERTSOCKOP(op, msg) \
        if( (op) == -1 ) \
                return dcc_abort( df , msg ": %s", strerror( errno ) );

/* Creates the "DCC SEND" line and sends it to the server */
int dccs_send_request( struct dcc_file_transfer *df, char *user_nick, struct sockaddr_storage *saddr )
{
        char ipaddr[INET6_ADDRSTRLEN]; 
        const void *netaddr;
        int port;
        char *cmd;

        if( saddr->ss_family == AF_INET )
        {
                struct sockaddr_in *saddr_ipv4 = ( struct sockaddr_in *) saddr;

                sprintf( ipaddr, "%d", 
                         ntohl( saddr_ipv4->sin_addr.s_addr ) );
                port = saddr_ipv4->sin_port;
        } else 
        {
                struct sockaddr_in6 *saddr_ipv6 = ( struct sockaddr_in6 *) saddr;

                netaddr = &saddr_ipv6->sin6_addr.s6_addr;
                port = saddr_ipv6->sin6_port;

                /* 
                 * Didn't find docs about this, but it seems that's the way irssi does it
                 */
                if( !inet_ntop( saddr->ss_family, netaddr, ipaddr, sizeof( ipaddr ) ) )
                        return dcc_abort( df, "inet_ntop failed: %s", strerror( errno ) );
        }

        port = ntohs( port );

        cmd = g_strdup_printf( "\001DCC SEND %s %s %u %zu\001",
                                df->ft->file_name, ipaddr, port, df->ft->file_size );
        
        if ( !irc_msgfrom( df->ic->irc, user_nick, cmd ) )
                return dcc_abort( df, "couldn't send 'DCC SEND' message to %s", user_nick );

        g_free( cmd );

        return TRUE;
}

/*
 * Creates a listening socket and returns it in saddr_ptr.
 */
gboolean dcc_listen( dcc_file_transfer_t *df, struct sockaddr_storage **saddr_ptr )
{
        file_transfer_t *file = df->ft;
        struct sockaddr_storage *saddr;
        int fd;
        char hostname[ HOST_NAME_MAX + 1 ];
        struct addrinfo hints, *rp;
        socklen_t ssize = sizeof( struct sockaddr_storage );

        /* won't be long till someone asks for this to be configurable :) */

        ASSERTSOCKOP( gethostname( hostname, sizeof( hostname ) ), "gethostname()" );

        memset( &hints, 0, sizeof( struct addrinfo ) );
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_NUMERICSERV;

        if ( getaddrinfo( hostname, "0", &hints, &rp ) != 0 )
                return dcc_abort( df, "getaddrinfo()" );

        saddr = g_new( struct sockaddr_storage, 1 );

        *saddr_ptr = saddr;

        memcpy( saddr, rp->ai_addr, rp->ai_addrlen );

        ASSERTSOCKOP( fd = df->fd = socket( saddr->ss_family, SOCK_STREAM, 0 ), "Opening socket" );

        ASSERTSOCKOP( bind( fd, ( struct sockaddr *)saddr, rp->ai_addrlen ), "Binding socket" );
        
        freeaddrinfo( rp );

        ASSERTSOCKOP( getsockname( fd, ( struct sockaddr *)saddr, &ssize ), "Getting socket name" );

        ASSERTSOCKOP( listen( fd, 1 ), "Making socket listen" );

        file->status = FT_STATUS_LISTENING;

        return TRUE;
}

/*
 * Checks poll(), same for receiving and sending
 */
gboolean dcc_poll( dcc_file_transfer_t *df, int fd, short *revents )
{
        struct pollfd pfd = { .fd = fd, .events = POLLHUP|POLLERR|POLLIN|POLLOUT };

        ASSERTSOCKOP( poll( &pfd, 1, 0 ), "poll()" )

        if( pfd.revents & POLLERR )
        {
                int sockerror;
                socklen_t errlen = sizeof( sockerror );

                if ( getsockopt( fd, SOL_SOCKET, SO_ERROR, &sockerror, &errlen ) )
                        return dcc_abort( df, "getsockopt() failed, unknown socket error (weird!)" );

                return dcc_abort( df, "Socket error: %s", strerror( sockerror ) );
        }
        
        if( pfd.revents & POLLHUP ) 
                return dcc_abort( df, "Remote end closed connection" );
        
        *revents = pfd.revents;

        return TRUE;
}

/*
 * fills max_packet_size with twice the TCP maximum segment size
 */
gboolean  dcc_check_maxseg( dcc_file_transfer_t *df, int fd )
{
        /* 
         * use twice the maximum segment size as a maximum for calls to send().
         */
        if( max_packet_size == 0 )
        {
                unsigned int mpslen = sizeof( max_packet_size );
                if( getsockopt( fd, IPPROTO_TCP, TCP_MAXSEG, &max_packet_size, &mpslen ) )
                        return dcc_abort( df, "getsockopt() failed" );
                max_packet_size *= 2;
        }
        return TRUE;
}

/*
 * After setup, the transfer itself is handled entirely by this function.
 * There are basically four things to handle: connect, receive, send, and error.
 */
gboolean dccs_send_proto( gpointer data, gint fd, b_input_condition cond )
{
        dcc_file_transfer_t *df = data;
        file_transfer_t *file = df->ft;
        short revents;
        
        if( !dcc_poll( df, fd, &revents) )
                return FALSE;

        if( ( revents & POLLIN ) &&
            ( file->status & FT_STATUS_LISTENING ) )
        {       
                struct sockaddr *clt_addr;
                socklen_t ssize = sizeof( clt_addr );

                /* Connect */

                ASSERTSOCKOP( df->fd = accept( fd, (struct sockaddr *) &clt_addr, &ssize ), "Accepting connection" );

                closesocket( fd );
                fd = df->fd;
                file->status = FT_STATUS_TRANSFERRING;
                sock_make_nonblocking( fd );

                if ( !dcc_check_maxseg( df, fd ) )
                        return FALSE;

                /* IM protocol callback */
                if( file->accept )
                        file->accept( file );

                /* reschedule for reading on new fd */
                df->watch_in = b_input_add( fd, GAIM_INPUT_READ, dccs_send_proto, df );

                return FALSE;
        }

        if( revents & POLLIN ) 
        {
                int bytes_received;
                int ret;
                
                ASSERTSOCKOP( ret = recv( fd, &bytes_received, sizeof( bytes_received  ), MSG_PEEK ), "Receiving" );

                if( ret == 0 )
                        return dcc_abort( df, "Remote end closed connection" );
                        
                if( ret < 4 )
                {
                        imcb_log( df->ic, "WARNING: DCC SEND: receiver sent only 2 bytes instead of 4, shouldn't happen too often!" );
                        return TRUE;
                }

                ASSERTSOCKOP( ret = recv( fd, &bytes_received, sizeof( bytes_received  ), 0 ), "Receiving" );
                if( ret != 4 )
                        return dcc_abort( df, "MSG_PEEK'ed 4, but can only dequeue %d bytes", ret );

                bytes_received = ntohl( bytes_received );

                /* If any of this is actually happening, the receiver should buy a new IRC client */

                if ( bytes_received > df->bytes_sent )
                        return dcc_abort( df, "Receiver magically received more bytes than sent ( %d > %d ) (BUG at receiver?)", bytes_received, df->bytes_sent );

                if ( bytes_received < file->bytes_transferred )
                        return dcc_abort( df, "Receiver lost bytes? ( has %d, had %d ) (BUG at receiver?)", bytes_received, file->bytes_transferred );
                
                file->bytes_transferred = bytes_received;
        
                if( file->bytes_transferred >= file->file_size ) {
                        dcc_finish( file );
                        return FALSE;
                }
        
                return TRUE;
        }

        return TRUE;
}

gboolean dccs_recv_start( file_transfer_t *ft )
{
        dcc_file_transfer_t *df = ft->priv;
        struct sockaddr_storage *saddr = &df->saddr;
        int fd;
        socklen_t sa_len = saddr->ss_family == AF_INET ? 
                sizeof( struct sockaddr_in ) : sizeof( struct sockaddr_in6 );
        
        if( !ft->write )
                return dcc_abort( df, "Protocol didn't register write()" );
        
        ASSERTSOCKOP( fd = df->fd = socket( saddr->ss_family, SOCK_STREAM, 0 ) , "Opening Socket" );

        sock_make_nonblocking( fd );

        if( ( connect( fd, (struct sockaddr *)saddr, sa_len ) == -1 ) &&
            ( errno != EINPROGRESS ) )
                return dcc_abort( df, "Connecting" );

        ft->status = FT_STATUS_CONNECTING;

        /* watch */
        df->watch_out = b_input_add( df->fd, GAIM_INPUT_WRITE, dccs_recv_proto, df );
        ft->write_request = dccs_recv_write_request;

        return TRUE;
}

gboolean dccs_recv_proto( gpointer data, gint fd, b_input_condition cond)
{
        dcc_file_transfer_t *df = data;
        file_transfer_t *ft = df->ft;
        short revents;

        if( !dcc_poll( df, fd, &revents ) )
                return FALSE;
        
        if( ( revents & POLLOUT ) &&
            ( ft->status & FT_STATUS_CONNECTING ) )
        {
                ft->status = FT_STATUS_TRANSFERRING;
                if ( !dcc_check_maxseg( df, fd ) )
                        return FALSE;

                //df->watch_in = b_input_add( df->fd, GAIM_INPUT_READ, dccs_recv_proto, df );

                df->watch_out = 0;
                return FALSE;
        }

        if( revents & POLLIN )
        {
                int ret, done;

                ASSERTSOCKOP( ret = recv( fd, ft->buffer, sizeof( ft->buffer ), 0 ), "Receiving" );

                if( ret == 0 )
                        return dcc_abort( df, "Remote end closed connection" );

                df->bytes_sent += ret;

                done = df->bytes_sent >= ft->file_size;

                if( ( ( df->bytes_sent - ft->bytes_transferred ) > DCC_PACKET_SIZE ) ||
                    done )
                {
                        int ack, ackret;
                        ack = htonl( ft->bytes_transferred = df->bytes_sent );

                        ASSERTSOCKOP( ackret = send( fd, &ack, 4, 0 ), "Sending DCC ACK" );
                        
                        if ( ackret != 4 )
                                return dcc_abort( df, "Error sending DCC ACK, sent %d instead of 4 bytes", ackret );
                }
                
                if( !ft->write( df->ft, ft->buffer, ret ) )
                        return FALSE;

                if( done )
                {
                        closesocket( fd );
                        dcc_finish( ft );

                        df->watch_in = 0;
                        return FALSE;
                }

                df->watch_in = 0;
                return FALSE;
        }

        return TRUE;
}

gboolean dccs_recv_write_request( file_transfer_t *ft )
{
        dcc_file_transfer_t *df = ft->priv;

        if( df->watch_in )
                return dcc_abort( df, "BUG: write_request() called while watching" );

        df->watch_in = b_input_add( df->fd, GAIM_INPUT_READ, dccs_recv_proto, df );

        return TRUE;
}

gboolean dccs_send_can_write( gpointer data, gint fd, b_input_condition cond )
{
        struct dcc_file_transfer *df = data;
        df->watch_out = 0;

        df->ft->write_request( df->ft );
        return FALSE;
}

/* 
 * Incoming data.
 * 
 */
gboolean dccs_send_write( file_transfer_t *file, char *data, unsigned int data_len )
{
        dcc_file_transfer_t *df = file->priv;
        int ret;

        receivedchunks++; receiveddata += data_len;

        if( df->watch_out )
                return dcc_abort( df, "BUG: write() called while watching" );

        ASSERTSOCKOP( ret = send( df->fd, data, data_len, 0 ), "Sending data" );

        if( ret == 0 )
                return dcc_abort( df, "Remote end closed connection" );

        /* TODO: this should really not be fatal */
        if( ret < data_len )
                return dcc_abort( df, "send() sent %d instead of %d", ret, data_len );

        df->bytes_sent += ret;

        if( df->bytes_sent < df->ft->file_size )
                df->watch_out = b_input_add( df->fd, GAIM_INPUT_WRITE, dccs_send_can_write, df );

        return TRUE;
}

/*
 * Cleans up after a transfer.
 */
static void dcc_close( file_transfer_t *file )
{
        dcc_file_transfer_t *df = file->priv;

        if( file->free )
                file->free( file );
        
        closesocket( df->fd );

        if( df->watch_in )
                b_event_remove( df->watch_in );

        if( df->watch_out )
                b_event_remove( df->watch_out );
        
        df->ic->irc->file_transfers = g_slist_remove( df->ic->irc->file_transfers, file );
        
        g_free( df );
        g_free( file->file_name );
        g_free( file );
}

void dcc_finish( file_transfer_t *file )
{
        file->status |= FT_STATUS_FINISHED;
        
        if( file->finished )
                file->finished( file );

        dcc_close( file );
}

/* 
 * DCC SEND <filename> <IP> <port> <filesize>
 *
 * filename can be in "" or not. If it is, " can probably be escaped...
 * IP can be an unsigned int (IPV4) or something else (IPV6)
 * 
 */
file_transfer_t *dcc_request( struct im_connection *ic, char *line )
{
        char *pattern = "SEND"
                " (([^\"][^ ]*)|\"([^\"]|\\\")*\")"
                " (([0-9]*)|([^ ]*))"
                " ([0-9]*)"
                " ([0-9]*)\001";
        regmatch_t pmatch[9];
        regex_t re;
        file_transfer_t *ft;
        dcc_file_transfer_t *df;

        if( regcomp( &re, pattern, REG_EXTENDED ) )
                return NULL;
        if( regexec( &re, line, 9, pmatch, 0 ) )
                return NULL;

        if( ( pmatch[1].rm_so > 0 ) &&
            ( pmatch[4].rm_so > 0 ) &&
            ( pmatch[7].rm_so > 0 ) &&
            ( pmatch[8].rm_so > 0 ) )
        {
                char *input = g_strdup( line );
                char *filename, *host, *port;
                size_t filesize;
                struct addrinfo hints, *rp;

                /* "filename" or filename */
                if ( pmatch[2].rm_so > 0 )
                {
                        input[pmatch[2].rm_eo] = '\0';
                        filename = input + pmatch[2].rm_so;
                } else
                {
                        input[pmatch[3].rm_eo] = '\0';
                        filename = input + pmatch[3].rm_so;
                }
                        
                input[pmatch[4].rm_eo] = '\0';

                /* number means ipv4, something else means ipv6 */
                if ( pmatch[5].rm_so > 0 )
                {
                        struct in_addr ipaddr = { htonl( atoi( input + pmatch[5].rm_so ) ) };
                        host = inet_ntoa( ipaddr );
                } else
                {
                        /* Contains non-numbers, hopefully an IPV6 address */
                        host = input + pmatch[6].rm_so;
                }

                input[pmatch[7].rm_eo] = '\0';
                input[pmatch[8].rm_eo] = '\0';

                port = input + pmatch[7].rm_so;
                filesize = atoll( input + pmatch[8].rm_so );

                memset( &hints, 0, sizeof ( struct addrinfo ) );
                if ( getaddrinfo( host, port, &hints, &rp ) )
                {
                        g_free( input );
                        return NULL;
                }

                df = dcc_alloc_transfer( filename, filesize, ic );
                ft = df->ft;
                ft->sending = TRUE;
                memcpy( &df->saddr, rp->ai_addr, rp->ai_addrlen );

                freeaddrinfo( rp );
                g_free( input );

                df->ic->irc->file_transfers = g_slist_prepend( df->ic->irc->file_transfers, ft );

                return ft;
        }

        return NULL;
}