session.c

一个功能非常全面的代理服务器源代码程序,

/* UNIX RFCNB (RFC1001/RFC1002) NetBIOS implementation
 * 
 * Version 1.0
 * Session Routines ...
 * 
 * Copyright (C) Richard Sharpe 1996
 * 
 */

/*
 * 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
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <string.h>
#include <stdlib.h>

int RFCNB_errno = 0;
int RFCNB_saved_errno = 0;
#define RFCNB_ERRNO

#include "std-includes.h"
#include <netinet/tcp.h>
#include "rfcnb-priv.h"
#include "rfcnb-util.h"
#include "rfcnb-io.h"

/* global data structures */

char *RFCNB_Error_Strings[] =
{

    "RFCNBE_OK: Routine completed successfully.",
    "RFCNBE_NoSpace: No space available for a malloc call.",
    "RFCNBE_BadName: NetBIOS name could not be translated to IP address.",
    "RFCNBE_BadRead: Read system call returned an error. Check errno.",
    "RFCNBE_BadWrite: Write system call returned an error. Check errno.",
    "RFCNBE_ProtErr: A protocol error has occurred.",
    "RFCNBE_ConGone: Connection dropped during a read or write system call.",
    "RFCNBE_BadHandle: Bad connection handle passed.",
    "RFCNBE_BadSocket: Problems creating socket.",
    "RFCNBE_ConnectFailed: Connection failed. See errno.",
    "RFCNBE_CallRejNLOCN: Call rejected. Not listening on called name.",
    "RFCNBE_CallRejNLFCN: Call rejected. Not listening for called name.",
    "RFCNBE_CallRejCNNP: Call rejected. Called name not present.",
    "RFCNBE_CallRejInfRes: Call rejected. Name present, but insufficient resources.",
    "RFCNBE_CallRejUnSpec: Call rejected. Unspecified error.",
    "RFCNBE_BadParam: Bad parameters passed to a routine.",
    "RFCNBE_Timeout: IO Operation timed out ..."

};

int RFCNB_Stats[RFCNB_MAX_STATS];

void (*Prot_Print_Routine) () = NULL;	/* Pointer to print routine */

/* Set up a session with a remote name. We are passed Called_Name as a
 * string which we convert to a NetBIOS name, ie space terminated, up to
 * 16 characters only if we need to. If Called_Address is not empty, then
 * we use it to connect to the remote end, but put in Called_Name ... Called 
 * Address can be a DNS based name, or a TCP/IP address ...
 */

void *
RFCNB_Call(char *Called_Name, char *Calling_Name, char *Called_Address,
    int port)
{
    struct RFCNB_Con *con;
    struct in_addr Dest_IP;
    int Client;
    BOOL redirect;
    struct redirect_addr *redir_addr;
    char *Service_Address;

    /* Now, we really should look up the port in /etc/services ... */

    if (port == 0)
	port = RFCNB_Default_Port;

    /* Create a connection structure first */

    if ((con = (struct RFCNB_Con *) malloc(sizeof(struct RFCNB_Con))) == NULL) {	/* Error in size */

	RFCNB_errno = RFCNBE_NoSpace;
	RFCNB_saved_errno = errno;
	return (NULL);

    }
    con->fd = -0;		/* no descriptor yet */
    con->rfc_errno = 0;		/* no error yet */
    con->timeout = 0;		/* no timeout   */
    con->redirects = 0;
    con->redirect_list = NULL;	/* Fix bug still in version 0.50 */

    /* Resolve that name into an IP address */

    Service_Address = Called_Name;
    if (strcmp(Called_Address, "") != 0) {	/* If the Called Address = "" */
	Service_Address = Called_Address;
    }
    if ((errno = RFCNB_Name_To_IP(Service_Address, &Dest_IP)) < 0) {	/* Error */

	/* No need to modify RFCNB_errno as it was done by RFCNB_Name_To_IP */

	return (NULL);

    }
    /* Now connect to the remote end */

    redirect = TRUE;		/* Fudge this one so we go once through */

    while (redirect) {		/* Connect and get session info etc */

	redirect = FALSE;	/* Assume all OK */

	/* Build the redirect info. First one is first addr called */
	/* And tack it onto the list of addresses we called        */

	if ((redir_addr = (struct redirect_addr *) malloc(sizeof(struct redirect_addr))) == NULL) {	/* Could not get space */

	    RFCNB_errno = RFCNBE_NoSpace;
	    RFCNB_saved_errno = errno;
	    return (NULL);

	}
	memcpy((char *) &(redir_addr->ip_addr), (char *) &Dest_IP, sizeof(Dest_IP));
	redir_addr->port = port;
	redir_addr->next = NULL;

	if (con->redirect_list == NULL) {	/* Stick on head */

	    con->redirect_list = con->last_addr = redir_addr;

	} else {

	    con->last_addr->next = redir_addr;
	    con->last_addr = redir_addr;

	}

	/* Now, make that connection */

	if ((Client = RFCNB_IP_Connect(Dest_IP, port)) < 0) {	/* Error */

	    /* No need to modify RFCNB_errno as it was done by RFCNB_IP_Connect */

	    return (NULL);

	}
	con->fd = Client;

	/* Now send and handle the RFCNB session request              */
	/* If we get a redirect, we will comeback with redirect true 
	 * and a new IP address in DEST_IP                            */

	if ((errno = RFCNB_Session_Req(con,
		    Called_Name,
		    Calling_Name,
		    &redirect, &Dest_IP, &port)) < 0) {

	    /* No need to modify RFCNB_errno as it was done by RFCNB_Session.. */

	    return (NULL);

	}
	if (redirect) {

	    /* We have to close the connection, and then try again */

	    (con->redirects)++;

	    RFCNB_Close(con->fd);	/* Close it */

	}
    }

    return (con);

}

/* We send a packet to the other end ... for the moment, we treat the 
 * data as a series of pointers to blocks of data ... we should check the
 * length ... */

int
RFCNB_Send(struct RFCNB_Con *Con_Handle, struct RFCNB_Pkt *udata, int Length)
{
    struct RFCNB_Pkt *pkt;
    char *hdr;
    int len;

    /* Plug in the header and send the data */

    pkt = RFCNB_Alloc_Pkt(RFCNB_Pkt_Hdr_Len);

    if (pkt == NULL) {

	RFCNB_errno = RFCNBE_NoSpace;
	RFCNB_saved_errno = errno;
	return (RFCNBE_Bad);

    }
    pkt->next = udata;		/* The user data we want to send */

    hdr = pkt->data;

    /* Following crap is for portability across multiple UNIX machines */

    *(hdr + RFCNB_Pkt_Type_Offset) = RFCNB_SESSION_MESSAGE;
    RFCNB_Put_Pkt_Len(hdr, Length);

#ifdef RFCNB_DEBUG

    fprintf(stderr, "Sending packet: ");

#endif

    if ((len = RFCNB_Put_Pkt(Con_Handle, pkt, Length + RFCNB_Pkt_Hdr_Len)) < 0) {

	/* No need to change RFCNB_errno as it was done by put_pkt ...     */

	return (RFCNBE_Bad);	/* Should be able to write that lot ... */

    }
    /* Now we have sent that lot, let's get rid of the RFCNB Header and return */

    pkt->next = NULL;

    RFCNB_Free_Pkt(pkt);

    return (len);

}

/* We pick up a message from the internet ... We have to worry about 
 * non-message packets ...                                           */

int
RFCNB_Recv(void *con_Handle, struct RFCNB_Pkt *Data, int Length)
{
    struct RFCNB_Pkt *pkt;
    int ret_len;

    if (con_Handle == NULL) {

	RFCNB_errno = RFCNBE_BadHandle;
	RFCNB_saved_errno = errno;
	return (RFCNBE_Bad);

    }
    /* Now get a packet from below. We allocate a header first */

    /* Plug in the header and send the data */

    pkt = RFCNB_Alloc_Pkt(RFCNB_Pkt_Hdr_Len);

    if (pkt == NULL) {

	RFCNB_errno = RFCNBE_NoSpace;
	RFCNB_saved_errno = errno;
	return (RFCNBE_Bad);

    }
    pkt->next = Data;		/* Plug in the data portion */

    if ((ret_len = RFCNB_Get_Pkt(con_Handle, pkt, Length + RFCNB_Pkt_Hdr_Len)) < 0) {

#ifdef RFCNB_DEBUG
	fprintf(stderr, "Bad packet return in RFCNB_Recv... \n");
#endif

	return (RFCNBE_Bad);

    }
    /* We should check that we go a message and not a keep alive */

    pkt->next = NULL;

    RFCNB_Free_Pkt(pkt);

    return (ret_len);

}

/* We just disconnect from the other end, as there is nothing in the RFCNB */
/* protocol that specifies any exchange as far as I can see                */

int
RFCNB_Hangup(struct RFCNB_Con *con_Handle)
{

    if (con_Handle != NULL) {
	RFCNB_Close(con_Handle->fd);	/* Could this fail? */
	free(con_Handle);
    }
    return 0;


}

/* Set TCP_NODELAY on the socket                                          */

int
RFCNB_Set_Sock_NoDelay(struct RFCNB_Con *con_Handle, BOOL yn)
{

    return (setsockopt(con_Handle->fd, IPPROTO_TCP, TCP_NODELAY,
	    (char *) &yn, sizeof(yn)));

}


/* Listen for a connection on a port???, when                             */
/* the connection comes in, we return with the connection                 */

void *
RFCNB_Listen()
{
    fprintf(stderr, "RFCNB_Listen NOT IMPLEMENTED as yet!\n");
    return NULL;
}

/* Pick up the last error response as a string, hmmm, this routine should */
/* have been different ...                                                */

void
RFCNB_Get_Error(char *buffer, int buf_len)
{

    if (RFCNB_saved_errno <= 0) {
	sprintf(buffer, "%s", RFCNB_Error_Strings[RFCNB_errno]);
    } else {
	sprintf(buffer, "%s\n\terrno:%s", RFCNB_Error_Strings[RFCNB_errno],
	    strerror(RFCNB_saved_errno));
    }

}

/* Pick up the last error response and returns as a code                 */

int
RFCNB_Get_Last_Error()
{

    return (RFCNB_errno);

}

/* Pick up saved errno as well */

int
RFCNB_Get_Last_Errno()
{

    return (RFCNB_saved_errno);

}

/* Pick up the last error response and return in string ...             */

void
RFCNB_Get_Error_Msg(int code, char *msg_buf, int len)
{

    strncpy(msg_buf, RFCNB_Error_Strings[abs(code)], len);

}

/* Register a higher level protocol print routine */

void
RFCNB_Register_Print_Routine(void (*fn) ())
{

    Prot_Print_Routine = fn;

}