resolvlib.c

VXWORKS源代码

    char *             pHostBuf,
    int                bufLen
    )
    {
    struct hostent *       pHostEnt;         /* Ptr to host entry */

    if (pInetAddr == NULL || pHostBuf == NULL)
        {
        errnoSet (S_resolvLib_INVALID_PARAMETER);
        return (NULL);
        }

    /* Format input buffer for use as a hostent structure */
    pHostEnt = hostEntFormat (&pHostBuf, &bufLen, MAXALIASES, MAXADDRS);

    if (pHostEnt == NULL)
        {
        errno = S_resolvLib_BUFFER_2_SMALL;
        return (NULL);
        }

    /* Check the hostLib static host table first ? */
    if (resolvParams.queryOrder == QUERY_LOCAL_FIRST)
        {
        if (resolvHostGetByAddr (pInetAddr, pHostEnt, pHostBuf, bufLen) != NULL)
            {
            return (pHostEnt);
            }
        }

    /* 
     * Ask the DNS Server to resolve the query.  In the case of queryOrder set
     * to QUERY_ DNS_ONLY, this is the only query done.
     */
    if (_gethostbyaddr (pInetAddr, 4, AF_INET, pHostEnt, pHostBuf, bufLen))
        {
        return (pHostEnt);      /* Got an answer from the DNS server */
        }

    /* We need to check the hostLib static host table next */
    if (resolvParams.queryOrder == QUERY_DNS_FIRST)
        {
        if (resolvHostGetByAddr (pInetAddr, pHostEnt, pHostBuf, bufLen) != NULL)
            {
            return (pHostEnt);
            }
        }

    return (NULL);             /* Host Name Not found */
    }

/*******************************************************************************
*
* resolvParamsSet - set the parameters which control the resolver library
*
* This routine sets the resolver parameters.  <pResolvParams> passes in
* a pointer to a RESOLV_PARAMS_S structure, which is defined as follows: 
* .CS
*     typedef struct
*        {
*        char   queryOrder;
*        char   domainName [MAXDNAME];
*        char   nameServersAddr [MAXNS][MAXIPADDRLEN];
*        } RESOLV_PARAMS_S;
* .CE
* Use the members of this structure to specify the settings you want to 
* apply to the resolver.  It is important to remember that multiple tasks 
* can use the resolver library and that the settings specified in 
* this RESOLV_PARAMS_S structure affect all queries from all tasks.  In 
* addition, you should set resolver parameters at initialization and not 
* while queries could be in progress. Otherwise, the results of the query 
* are unpredictable.  
*
* Before calling resolvParamsSet(), you should first call resolvParamsGet() 
* to populate a RESOLV_PARAMS_S structure with the current settings.  Then
* you change the values of the members that interest you.    
*
* Valid values for the `queryOrder' member of RESOLV_PARAMS_S structure 
* are defined in resolvLib.h.  Set the `domainName' member to the domain to 
* which this resolver belongs.  Set the `nameServersAddr' member to the IP 
* addresses of the DNS server that the resolver can query.  You must specify 
* the IP addresses in standard dotted decimal notation.  This function tries 
* to validate the values in the `queryOrder' and `nameServerAddr' members.  
* This function does not try to validate the domain name.  
*
* RETURNS: OK if the parameters are valid, ERROR otherwise.
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvDNExpand(),
* resolvDNComp(), resolvSend(), resolvInit(), resolvParamsGet(),
* resolvMkQuery(), resolvQuery()
*/

STATUS resolvParamsSet 
    (
    RESOLV_PARAMS_S *  pResolvParams  /* ptr to resolver parameter struct */
    )
    {
    struct in_addr   ipAddr;
    int               index;

   /* Validate queryOrder parameters */

   if (pResolvParams->queryOrder != QUERY_LOCAL_FIRST && 
       pResolvParams->queryOrder != QUERY_DNS_FIRST &&
       pResolvParams->queryOrder != QUERY_DNS_ONLY)
       return (ERROR);


    /* Validate IP addresses */

    for (index = 0 ; (index < MAXNS) && 
	 (pResolvParams->nameServersAddr [index][0] != '\0'); index++)
	{
	if (inet_aton (pResolvParams->nameServersAddr [index], &ipAddr) != OK)
		return(ERROR);
	}

    /* Update queryOrder parameter */

    resolvParams.queryOrder = pResolvParams->queryOrder;

    /* Update the name server IP addresses in decimal dot notation */

    for (index = 0, _res.nscount = 0; (index < MAXNS) && 
	 (pResolvParams->nameServersAddr [index][0] != '\0'); index++)
	{
	
	(void) inet_aton (pResolvParams->nameServersAddr [index], &ipAddr);

	/* update the resolver server entry */

	_res.nsaddr_list [index].sin_addr = ipAddr;
	_res.nsaddr_list [index].sin_family = AF_INET;
	_res.nsaddr_list [index].sin_port = htons(NAMESERVER_PORT);
        _res.lookups [index] = 'b';
        _res.nscount++;  /* Number of DNS servers to query */
	}

    _res.lookups [index] = 'f';

    /* Update domain name; Assume a valid domain name */

    (void) strcpy (_res.defdname, pResolvParams->domainName);

    return (OK);
    }

/*******************************************************************************
*
* resolvParamsGet - get the parameters which control the resolver library
*
* This routine copies the resolver parameters to the RESOLV_PARAMS_S
* structure referenced in the <pResolvParms> parameter.  The RESOLV_PARAMS_S
* structure is defined in resolvLib.h as follows: 
* .CS
*     typedef struct
*        {
*        char   queryOrder;
*        char   domainName [MAXDNAME];
*        char   nameServersAddr [MAXNS][MAXIPADDRLEN];
*        } RESOLV_PARAMS_S;
* .CE
* Typically, you call this function just before calling resolvParamsSet().
* The resolvParamsGet() call populates the RESOLV_PARAMS_S structure. 
* You can then modify the default values just before calling 
* resolvParamsSet().  
*
* RETURNS: N/A
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvDNExpand(),
* resolvDNComp(), resolvSend(), resolvParamsSet(), resolvInit(),
* resolvMkQuery(), resolvQuery()
*/

void resolvParamsGet 
    (
    RESOLV_PARAMS_S *     pResolvParams  /* ptr to resolver parameter struct */
    )
    {
    int index;

    pResolvParams->queryOrder = resolvParams.queryOrder;

    (void) strcpy (pResolvParams->domainName, _res.defdname);
    
    /* Copy the name server IP addresses in decimal dot notation */ 
    for ( index = 0 ; index < MAXNS ; index++)
	{ 
	if (index < _res.nscount)
	    {
	    inet_ntoa_b (_res.nsaddr_list [index].sin_addr,
			 pResolvParams->nameServersAddr [index]);
	    }
	else
	    {
	    pResolvParams->nameServersAddr [index][0] = 0;
	    }
	}
    }

/*******************************************************************************
*
* resolvHostLibGetByName - query the DNS server in behalf of hostGetByName
*
* When the resolver library is installed, the routine hostGetByName() in the 
* hostLib library invokes this routine.  When the host name is not found by
* hostGetByName in the static host table.  This feature allows existing 
* applications to take advantage of the resolver without any changes.
*
* NOMANUAL
*
* ERRNO:
*  S_resolvLib_TRY_AGAIN
*  S_resolvLib_HOST_NOT_FOUND
*  S_resolvLib_NO_DATA
*  S_resolvLib_NO_RECOVERY
*
* RETURNS: IP address of host, or ERROR if the host was not found.
*/

LOCAL int resolvHostLibGetByName 
    (
    char * pHostName       /* Pointer to host name */
    )
    {
    char reqBuf [MAX_HOSTLIB_BUF];	       /* Holding buffer  */
    char *     pHostBuf;
    int        bufLen;
    struct hostent *       pHostEnt;           /* Ptr to host entry */

    /* Try to get the answer from the DNS Server */

    pHostBuf = reqBuf;
    bufLen   = sizeof(reqBuf);

    pHostEnt = hostEntFormat (& pHostBuf, & bufLen, MAXALIASES, MAXADDRS);

    pHostEnt = _gethostbyname (pHostName, pHostEnt, pHostBuf, bufLen);

    if (pHostEnt != NULL)
	{
	return (*(int *)(pHostEnt->h_addr_list [0])); /* Host IP address */
	}

    return (ERROR);  /* Host IP address not found ! */
    }

/*******************************************************************************
*
* resolvHostLibGetByAddr - query the DNS server in behalf of hostGetByAddr()
*
* When the resolver library is installed the routine hostGetByAddr() in the 
* hostLib library invokes this routine.  When the IP address is not found by
* hostGetByAddr() in the static host table.  This feature allows existing 
* applications to take advantage of the resolver without any changes.  The
* <addr> paramter specifies the IP address and <pHostName> points to the
* official name of the host when the query is successful.
*
* NOMANUAL
*
* ERRNO:
*  S_resolvLib_TRY_AGAIN
*  S_resolvLib_HOST_NOT_FOUND
*  S_resolvLib_NO_DATA
*  S_resolvLib_NO_RECOVERY
*
* RETURNS: OK, or ERROR if the host name was not found.
*/

LOCAL STATUS resolvHostLibGetByAddr
    (
    int   addr,			/* IP address of requested host name */
    char * pHostName		/* host name output by this routine */
    )
    {
    char reqBuf [MAX_HOSTLIB_BUF];	       /* Holding buffer  */
    char *     pHostBuf;
    int        bufLen;
    struct hostent *       pHostEnt;           /* Ptr to host entry */

    /* Try to get the answer from the DNS Server */

    pHostBuf = reqBuf;
    bufLen   = sizeof(reqBuf);

    pHostEnt = hostEntFormat (& pHostBuf, & bufLen, MAXALIASES, MAXADDRS);

    pHostEnt = _gethostbyaddr ((char *)&addr, 4, AF_INET, pHostEnt, 
			       pHostBuf, bufLen);

    if (pHostEnt != NULL)
	{
        strcpy (pHostName, pHostEnt->h_name);  /* Copy the host official name */
	return (OK);
	}

    return (ERROR);
    }

/*******************************************************************************
*
* resolvDNExpand - expand a DNS compressed name from a DNS packet
*
* This functions expands a compressed DNS name from a DNS packet.  The <msg>
* parameter points to that start of the DNS packet.  The <eomorig> parameter
* points to the last location of the DNS packet plus 1.  The <comp_dn> 
* parameter points to the compress domain name, and <exp_dn> parameter 
* expects a pointer to a buffer.  Upon function completion, this buffer 
* contains the expanded domain name.  Use the <length> parameter to pass in
* the size of the buffer referenced by the <exp_dn> parameter.  
*
* RETURNS: The length of the expanded domain name, or ERROR on failure.
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvInit(),
* resolvDNComp(), resolvSend(), resolvParamsSet(), resolvParamsGet(),
* resolvMkQuery(), resolvQuery()
*/

int resolvDNExpand 
    (
    const u_char * msg,     /* ptr to the start of the DNS packet */
    const u_char * eomorig, /* ptr to the last location +1 of the DNS packet */
    const u_char * comp_dn, /* ptr to the compressed domain name */
          u_char * exp_dn,  /* ptr to where the expanded DN is output */
          int      length   /* length of the buffer pointed by <expd_dn> */
    );

/*******************************************************************************
*
* resolvDNComp - compress a DNS name in a DNS packet
*
* This routine takes the expanded domain name referenced in the <exp_dn> 
* parameter, compresses it, and stores the compressed name in the location
* pointed to by the <comp_dn> parameter.  The <length> parameter passes in 
* the length of the buffer starting at <comp_dn>.  The <dnptrs> parameter 
* is a pointer to a list of pointers to previously compressed names.  The 
* <lastdnptr> parameter points to the last entry in the <dnptrs> array.
*
* RETURNS: The size of the compressed name, or ERROR.
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvDNExpand(),
* resolvInit(), resolvSend(), resolvParamsSet(), resolvParamsGet(),
* resolvMkQuery(), resolvQuery()
*/

int resolvDNComp 
    (
    const u_char *  exp_dn,   /* ptr to the expanded domain name */
          u_char *  comp_dn,  /* ptr to where to output the compressed name */  
          int       length,   /* length of the buffer pointed by <comp_dn> */
          u_char ** dnptrs,   /* ptr to a ptr list of compressed names */ 
          u_char ** lastdnptr /* ptr to the last entry pointed by <dnptrs> */
      );

/*******************************************************************************
*
* resolvQuery - construct a query, send it, wait for a response
*
* This routine constructs a query for the domain specified in the <name> 
* parameter.  The <class> parameter specifies the class of the query. 
* The <type> parameter specifies the type of query. The routine then sends
* the query to the DNS server.  When the server responds, the response is 
* validated and copied to the buffer you supplied in the <answer> parameter.
* Use the <anslen> parameter to pass in the size of the buffer referenced
* in <answer>.
*
* RETURNS: The length of the response or ERROR.
*
* ERRNO:
*  S_resolvLib_TRY_AGAIN
*  S_resolvLib_HOST_NOT_FOUND
*  S_resolvLib_NO_DATA
*  S_resolvLib_NO_RECOVERY
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvDNExpand(),
* resolvDNComp(), resolvInit(), resolvParamsSet(), resolvParamsGet(),
* resolvMkQuery()
*/

int resolvQuery 
    (
    char   *name,       /* domain name */
    int    class,       /* query class for IP is C_IN */
    int    type,        /* type is T_A, T_PTR, ... */
    u_char *answer,     /* buffer to put answer */
    int    anslen       /* length of answer buffer */
    );


/*******************************************************************************
*
* resolvMkQuery - create all types of DNS queries
*
* This routine uses the input parameters to create a domain name query.
* You can set the <op> parameter to QUERY or IQUERY.  Specify the domain 
* name in <dname>, the class in <class>, the query type in <type>.  Valid
* values for type include T_A, T_PTR, and so on.  Use <data> to add Resource 
* Record data to the query.  Use <datalen> to pass in the length of the 
* data buffer.  Set <newrr_in> to NULL.  This parameter is reserved for 
* future use.  The <buf> parameter expects a pointer to the output buffer 
* for the constructed query.  Use <buflen> to pass in the length of the 
* buffer referenced in <buf>.
*
* RETURNS: The length of the constructed query or ERROR.
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvDNExpand(),
* resolvDNComp(), resolvSend(), resolvParamsSet(), resolvParamsGet(),
* resolvInit(), resolvQuery()
*/

int resolvMkQuery 
    (
          int     op,	       /* set to desire query QUERY or IQUERY */
    const char *  dname,       /* domain name to be use in the query */
    int           class,       /* query class for IP is C_IN */
    int           type,        /* type is T_A, T_PTR, ... */
    const char *  data,        /* resource Record (RR) data */
    int           datalen,     /* length of the RR */
    const char *  newrr_in,    /* not used always set to NULL */
          char *  buf,         /* out of the constructed query */
          int     buflen       /* length of the buffer for the query */
    );

/*******************************************************************************
*
* resolvSend - send a pre-formatted query and return the answer
*
* This routine takes a pre-formatted DNS query and sends it to the domain
* server.  Use <buf> to pass in a pointer to the query.  Use <buflen> to 
* pass in the size of the buffer referenced in <buf>.  The <answer> parameter
* expects a pointer to a buffer into which this routine can write the 
* answer retrieved from the server.  Use <anslen> to pass in the size of
* the buffer you have provided in <anslen>.
*
* RETURNS: The length of the response or ERROR.
*
* ERRNO:
*  S_resolvLib_TRY_AGAIN
*  ECONNREFUSE
*  ETIMEDOU
*
* SEE ALSO:
* resolvGetHostByName(), resolvGetHostByAddr(), resolvDNExpand(),
* resolvDNComp(), resolvInit(), resolvParamsSet(), resolvParamsGet(),
* resolvMkQuery(), resolvQuery()
*/

int resolvSend 
    (
    const char * buf,		/* pre-formatted query */
          int    buflen,	/* length of query */
          char * answer,	/* buffer for answer */
          int    anslen		/* length of answer */
    );