ftp.c

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#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <byteswap.h>
#include <gpxe/socket.h>
#include <gpxe/tcpip.h>
#include <gpxe/in.h>
#include <gpxe/xfer.h>
#include <gpxe/open.h>
#include <gpxe/uri.h>
#include <gpxe/features.h>
#include <gpxe/ftp.h>

/** @file
 *
 * File transfer protocol
 *
 */

FEATURE ( FEATURE_PROTOCOL, "FTP", DHCP_EB_FEATURE_FTP, 1 );

/**
 * FTP states
 *
 * These @b must be sequential, i.e. a successful FTP session must
 * pass through each of these states in order.
 */
enum ftp_state {
        FTP_CONNECT = 0,
        FTP_USER,
        FTP_PASS,
        FTP_TYPE,
        FTP_PASV,
        FTP_RETR,
        FTP_WAIT,
        FTP_QUIT,
        FTP_DONE,
};

/**
 * An FTP request
 *
 */
struct ftp_request {
        /** Reference counter */
        struct refcnt refcnt;
        /** Data transfer interface */
        struct xfer_interface xfer;

        /** URI being fetched */
        struct uri *uri;
        /** FTP control channel interface */
        struct xfer_interface control;
        /** FTP data channel interface */
        struct xfer_interface data;

        /** Current state */
        enum ftp_state state;
        /** Buffer to be filled with data received via the control channel */
        char *recvbuf;
        /** Remaining size of recvbuf */
        size_t recvsize;
        /** FTP status code, as text */
        char status_text[5];
        /** Passive-mode parameters, as text */
        char passive_text[24]; /* "aaa,bbb,ccc,ddd,eee,fff" */
};

/**
 * Free FTP request
 *
 * @v refcnt            Reference counter
 */
static void ftp_free ( struct refcnt *refcnt ) {
        struct ftp_request *ftp =
                container_of ( refcnt, struct ftp_request, refcnt );

        DBGC ( ftp, "FTP %p freed\n", ftp );

        uri_put ( ftp->uri );
        free ( ftp );
}

/**
 * Mark FTP operation as complete
 *
 * @v ftp               FTP request
 * @v rc                Return status code
 */
static void ftp_done ( struct ftp_request *ftp, int rc ) {

        DBGC ( ftp, "FTP %p completed (%s)\n", ftp, strerror ( rc ) );

        /* Close all data transfer interfaces */
        xfer_nullify ( &ftp->xfer );
        xfer_close ( &ftp->xfer, rc );
        xfer_nullify ( &ftp->control );
        xfer_close ( &ftp->control, rc );
        xfer_nullify ( &ftp->data );
        xfer_close ( &ftp->data, rc );
}

/*****************************************************************************
 *
 * FTP control channel
 *
 */

/** An FTP control channel string */
struct ftp_control_string {
        /** Literal portion */
        const char *literal;
        /** Variable portion
         *
         * @v ftp       FTP request
         * @ret string  Variable portion of string
         */
        const char * ( *variable ) ( struct ftp_request *ftp );
};

/**
 * Retrieve FTP pathname
 *
 * @v ftp               FTP request
 * @ret path            FTP pathname
 */
static const char * ftp_uri_path ( struct ftp_request *ftp ) {
        return ftp->uri->path;
}

/**
 * Retrieve FTP user
 *
 * @v ftp               FTP request
 * @ret user            FTP user
 */
static const char * ftp_user ( struct ftp_request *ftp ) {
        static char *ftp_default_user = "anonymous";
        return ftp->uri->user ? ftp->uri->user : ftp_default_user;
}

/**
 * Retrieve FTP password
 *
 * @v ftp               FTP request
 * @ret password        FTP password
 */
static const char * ftp_password ( struct ftp_request *ftp ) {
        static char *ftp_default_password = "etherboot@etherboot.org";
        return ftp->uri->password ? ftp->uri->password : ftp_default_password;
}

/** FTP control channel strings */
static struct ftp_control_string ftp_strings[] = {
        [FTP_CONNECT]   = { NULL, NULL },
        [FTP_USER]      = { "USER ", ftp_user },
        [FTP_PASS]      = { "PASS ", ftp_password },
        [FTP_TYPE]      = { "TYPE I", NULL },
        [FTP_PASV]      = { "PASV", NULL },
        [FTP_RETR]      = { "RETR ", ftp_uri_path },
        [FTP_WAIT]      = { NULL, NULL },
        [FTP_QUIT]      = { "QUIT", NULL },
        [FTP_DONE]      = { NULL, NULL },
};

/**
 * Handle control channel being closed
 *
 * @v control           FTP control channel interface
 * @v rc                Reason for close
 *
 * When the control channel is closed, the data channel must also be
 * closed, if it is currently open.
 */
static void ftp_control_close ( struct xfer_interface *control, int rc ) {
        struct ftp_request *ftp =
                container_of ( control, struct ftp_request, control );

        DBGC ( ftp, "FTP %p control connection closed: %s\n",
               ftp, strerror ( rc ) );

        /* Complete FTP operation */
        ftp_done ( ftp, rc );
}

/**
 * Parse FTP byte sequence value
 *
 * @v text              Text string
 * @v value             Value buffer
 * @v len               Length of value buffer
 *
 * This parses an FTP byte sequence value (e.g. the "aaa,bbb,ccc,ddd"
 * form for IP addresses in PORT commands) into a byte sequence.  @c
 * *text will be updated to point beyond the end of the parsed byte
 * sequence.
 *
 * This function is safe in the presence of malformed data, though the
 * output is undefined.
 */
static void ftp_parse_value ( char **text, uint8_t *value, size_t len ) {
        do {
                *(value++) = strtoul ( *text, text, 10 );
                if ( **text )
                        (*text)++;
        } while ( --len );
}

/**
 * Move to next state and send the appropriate FTP control string
 *
 * @v ftp               FTP request
 *
 */
static void ftp_next_state ( struct ftp_request *ftp ) {
        struct ftp_control_string *ftp_string;
        const char *literal;
        const char *variable;

        /* Move to next state */
        if ( ftp->state < FTP_DONE )
                ftp->state++;

        /* Send control string if needed */
        ftp_string = &ftp_strings[ftp->state];
        literal = ftp_string->literal;
        variable = ( ftp_string->variable ?
                     ftp_string->variable ( ftp ) : "" );
        if ( literal ) {
                DBGC ( ftp, "FTP %p sending %s%s\n", ftp, literal, variable );
                xfer_printf ( &ftp->control, "%s%s\r\n", literal, variable );
        }
}

/**
 * Handle an FTP control channel response
 *
 * @v ftp               FTP request
 *
 * This is called once we have received a complete response line.
 */
static void ftp_reply ( struct ftp_request *ftp ) {
        char status_major = ftp->status_text[0];
        char separator = ftp->status_text[3];

        DBGC ( ftp, "FTP %p received status %s\n", ftp, ftp->status_text );

        /* Ignore malformed lines */
        if ( separator != ' ' )
                return;

        /* Ignore "intermediate" responses (1xx codes) */
        if ( status_major == '1' )
                return;

        /* Anything other than success (2xx) or, in the case of a
         * repsonse to a "USER" command, a password prompt (3xx), is a
         * fatal error.
         */
        if ( ! ( ( status_major == '2' ) ||
                 ( ( status_major == '3' ) && ( ftp->state == FTP_USER ) ) ) ){
                /* Flag protocol error and close connections */
                ftp_done ( ftp, -EPROTO );
                return;
        }

        /* Open passive connection when we get "PASV" response */
        if ( ftp->state == FTP_PASV ) {
                char *ptr = ftp->passive_text;
                union {
                        struct sockaddr_in sin;
                        struct sockaddr sa;
                } sa;
                int rc;

                sa.sin.sin_family = AF_INET;
                ftp_parse_value ( &ptr, ( uint8_t * ) &sa.sin.sin_addr,
                                  sizeof ( sa.sin.sin_addr ) );
                ftp_parse_value ( &ptr, ( uint8_t * ) &sa.sin.sin_port,
                                  sizeof ( sa.sin.sin_port ) );
                if ( ( rc = xfer_open_socket ( &ftp->data, SOCK_STREAM,
                                               &sa.sa, NULL ) ) != 0 ) {
                        DBGC ( ftp, "FTP %p could not open data connection\n",
                               ftp );
                        ftp_done ( ftp, rc );
                        return;
                }
        }

        /* Move to next state and send control string */
        ftp_next_state ( ftp );
        
}

/**
 * Handle new data arriving on FTP control channel
 *
 * @v control           FTP control channel interface
 * @v data              New data
 * @v len               Length of new data
 *
 * Data is collected until a complete line is received, at which point
 * its information is passed to ftp_reply().
 */
static int ftp_control_deliver_raw ( struct xfer_interface *control,
                                     const void *data, size_t len ) {
        struct ftp_request *ftp =
                container_of ( control, struct ftp_request, control );
        char *recvbuf = ftp->recvbuf;
        size_t recvsize = ftp->recvsize;
        char c;
        
        while ( len-- ) {
                c = * ( ( char * ) data++ );
                switch ( c ) {
                case '\r' :
                case '\n' :
                        /* End of line: call ftp_reply() to handle
                         * completed reply.  Avoid calling ftp_reply()
                         * twice if we receive both \r and \n.
                         */
                        if ( recvsize == 0 )
                                ftp_reply ( ftp );
                        /* Start filling up the status code buffer */
                        recvbuf = ftp->status_text;
                        recvsize = sizeof ( ftp->status_text ) - 1;
                        break;
                case '(' :
                        /* Start filling up the passive parameter buffer */
                        recvbuf = ftp->passive_text;
                        recvsize = sizeof ( ftp->passive_text ) - 1;
                        break;
                case ')' :
                        /* Stop filling the passive parameter buffer */
                        recvsize = 0;
                        break;
                default :
                        /* Fill up buffer if applicable */
                        if ( recvsize > 0 ) {
                                *(recvbuf++) = c;
                                recvsize--;
                        }
                        break;
                }
        }

        /* Store for next invocation */
        ftp->recvbuf = recvbuf;
        ftp->recvsize = recvsize;

        return 0;
}

/** FTP control channel operations */
static struct xfer_interface_operations ftp_control_operations = {
        .close          = ftp_control_close,
        .vredirect      = xfer_vreopen,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ftp_control_deliver_raw,
};

/*****************************************************************************
 *
 * FTP data channel
 *
 */

/**
 * Handle FTP data channel being closed
 *
 * @v data              FTP data channel interface
 * @v rc                Reason for closure
 *
 * When the data channel is closed, the control channel should be left
 * alone; the server will send a completion message via the control
 * channel which we'll pick up.
 *
 * If the data channel is closed due to an error, we abort the request.
 */
static void ftp_data_closed ( struct xfer_interface *data, int rc ) {
        struct ftp_request *ftp =
                container_of ( data, struct ftp_request, data );

        DBGC ( ftp, "FTP %p data connection closed: %s\n",
               ftp, strerror ( rc ) );
        
        /* If there was an error, close control channel and record status */
        if ( rc ) {
                ftp_done ( ftp, rc );
        } else {
                ftp_next_state ( ftp );
        }
}

/**
 * Handle data delivery via FTP data channel
 *
 * @v xfer              FTP data channel interface
 * @v iobuf             I/O buffer
 * @v meta              Data transfer metadata
 * @ret rc              Return status code
 */
static int ftp_data_deliver_iob ( struct xfer_interface *data,
                                  struct io_buffer *iobuf,
                                  struct xfer_metadata *meta __unused ) {
        struct ftp_request *ftp =
                container_of ( data, struct ftp_request, data );
        int rc;

        if ( ( rc = xfer_deliver_iob ( &ftp->xfer, iobuf ) ) != 0 ) {
                DBGC ( ftp, "FTP %p failed to deliver data: %s\n",
                       ftp, strerror ( rc ) );
                return rc;
        }

        return 0;
}

/** FTP data channel operations */
static struct xfer_interface_operations ftp_data_operations = {
        .close          = ftp_data_closed,
        .vredirect      = xfer_vreopen,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = ftp_data_deliver_iob,
        .deliver_raw    = xfer_deliver_as_iob,
};

/*****************************************************************************
 *
 * Data transfer interface
 *
 */

/**
 * Close FTP data transfer interface
 *
 * @v xfer              FTP data transfer interface
 * @v rc                Reason for close
 */
static void ftp_xfer_closed ( struct xfer_interface *xfer, int rc ) {
        struct ftp_request *ftp =
                container_of ( xfer, struct ftp_request, xfer );

        DBGC ( ftp, "FTP %p data transfer interface closed: %s\n",
               ftp, strerror ( rc ) );
        
        ftp_done ( ftp, rc );
}

/** FTP data transfer interface operations */
static struct xfer_interface_operations ftp_xfer_operations = {
        .close          = ftp_xfer_closed,
        .vredirect      = ignore_xfer_vredirect,
        .window         = unlimited_xfer_window,
        .alloc_iob      = default_xfer_alloc_iob,
        .deliver_iob    = xfer_deliver_as_raw,
        .deliver_raw    = ignore_xfer_deliver_raw,
};

/*****************************************************************************
 *
 * URI opener
 *
 */

/**
 * Initiate an FTP connection
 *
 * @v xfer              Data transfer interface
 * @v uri               Uniform Resource Identifier
 * @ret rc              Return status code
 */
static int ftp_open ( struct xfer_interface *xfer, struct uri *uri ) {
        struct ftp_request *ftp;
        struct sockaddr_tcpip server;
        int rc;

        /* Sanity checks */
        if ( ! uri->path )
                return -EINVAL;
        if ( ! uri->host )
                return -EINVAL;

        /* Allocate and populate structure */
        ftp = zalloc ( sizeof ( *ftp ) );
        if ( ! ftp )
                return -ENOMEM;
        ftp->refcnt.free = ftp_free;
        xfer_init ( &ftp->xfer, &ftp_xfer_operations, &ftp->refcnt );
        ftp->uri = uri_get ( uri );
        xfer_init ( &ftp->control, &ftp_control_operations, &ftp->refcnt );
        xfer_init ( &ftp->data, &ftp_data_operations, &ftp->refcnt );
        ftp->recvbuf = ftp->status_text;
        ftp->recvsize = sizeof ( ftp->status_text ) - 1;

        DBGC ( ftp, "FTP %p fetching %s\n", ftp, ftp->uri->path );

        /* Open control connection */
        memset ( &server, 0, sizeof ( server ) );
        server.st_port = htons ( uri_port ( uri, FTP_PORT ) );
        if ( ( rc = xfer_open_named_socket ( &ftp->control, SOCK_STREAM,
                                             ( struct sockaddr * ) &server,
                                             uri->host, NULL ) ) != 0 )
                goto err;

        /* Attach to parent interface, mortalise self, and return */
        xfer_plug_plug ( &ftp->xfer, xfer );
        ref_put ( &ftp->refcnt );
        return 0;

 err:
        DBGC ( ftp, "FTP %p could not create request: %s\n", 
               ftp, strerror ( rc ) );
        ftp_done ( ftp, rc );
        ref_put ( &ftp->refcnt );
        return rc;
}

/** FTP URI opener */
struct uri_opener ftp_uri_opener __uri_opener = {
        .scheme = "ftp",
        .open   = ftp_open,
};