main.c

一个可用的dns服务器源代码

    exit(0);
}


void
LocalServer(defaultPtr)
    HostInfo *defaultPtr;
{
    char	hostName[NAME_LEN];

    (void) gethostname(hostName, sizeof(hostName));

#ifndef WINNT
    defaultAddr.s_addr = htonl(INADDR_ANY); 
      (void) GetHostInfoByName(&defaultAddr, C_IN, T_A,
			     "0.0.0.0", defaultPtr, 1);
#else /* lgk the 0.0.0.0 doesn't work for nt so set to loopback */
    defaultAddr.s_addr = htonl(INADDR_LOOPBACK);
          (void) GetHostInfoByName(&defaultAddr, C_IN, T_A,
			     "127.0.0.1", defaultPtr, 1);

#endif
  
    free(defaultPtr->name);
    defaultPtr->name = Calloc(1, sizeof(hostName)+1);
    strcpy(defaultPtr->name, hostName);
}


/*
 ******************************************************************************
 *
 *  Usage --
 *
 *	Lists the proper methods to run the program and exits.
 *
 ******************************************************************************
 */

void 
Usage()
{
    fprintf(stderr, "Usage:\n");
    fprintf(stderr,
"   nslookup [-opt ...]             # interactive mode using default server\n");
    fprintf(stderr,
"   nslookup [-opt ...] - server    # interactive mode using 'server'\n");
    fprintf(stderr,
"   nslookup [-opt ...] host        # just look up 'host' using default server\n");
    fprintf(stderr,
"   nslookup [-opt ...] host server # just look up 'host' using 'server'\n");
    exit(1);
}

/*
 ******************************************************************************
 *
 * IsAddr --
 *
 *	Returns TRUE if the string looks like an Internet address.
 *	A string with a trailing dot is not an address, even if it looks
 *	like one.
 *
 ******************************************************************************
 */

Boolean
IsAddr(host, addrPtr)
    char *host;
    struct in_addr *addrPtr;	/* If return TRUE, contains IP address */
{
    register char *cp;

    if (isdigit(host[0])) {
	    /* Make sure it has only digits and dots. */
	    for (cp = host; *cp; ++cp) {
		if (!isdigit(*cp) && *cp != '.') 
		    return FALSE;
	    }
	    /* If it has a trailing dot, don't treat it as an address. */
	    if (*--cp != '.') { 
		return inet_aton(host, addrPtr);
	    }
    }
    return FALSE;
}


/*
 ******************************************************************************
 *
 *  SetDefaultServer --
 *
 *	Changes the default name server to the one specified by
 *	the first argument. The command "server name" uses the current 
 *	default server to lookup the info for "name". The command
 *	"lserver name" uses the original server to lookup "name".
 *
 *  Side effects:
 *	This routine will cause a core dump if the allocation requests fail.
 *
 *  Results:
 *	SUCCESS		The default server was changed successfully.
 *	NONAUTH		The server was changed but addresses of
 *			other servers who know about the requested server
 *			were returned.
 *	Errors		No info about the new server was found or
 *			requests to the current server timed-out.
 *
 ******************************************************************************
 */

int
SetDefaultServer(string, local)
    char	*string;
    Boolean	local;
{
    register HostInfo	*newDefPtr;
    struct in_addr	*servAddrPtr;
    struct in_addr	addr;
    char		newServer[NAME_LEN];
    int			result;
    int			i;

    /*
     *  Parse the command line. It maybe of the form "server name",
     *  "lserver name" or just "name".
     */

    if (local) {
	i = sscanf(string, " lserver %s", newServer);
    } else {
	i = sscanf(string, " server %s", newServer);
    }
    if (i != 1) {
	i = sscanf(string, " %s", newServer);
	if (i != 1) {
	    fprintf(stderr,"SetDefaultServer: invalid name: %s\n",  string);
	    return(ERROR);
	}
    }

    /*
     * Allocate space for a HostInfo variable for the new server. Don't
     * overwrite the old HostInfo struct because info about the new server
     * might not be found and we need to have valid default server info.
     */

    newDefPtr = (HostInfo *) Calloc(1, sizeof(HostInfo));


    /*
     *	A 'local' lookup uses the original server that the program was
     *  initialized with.
     *
     *  Check to see if we have the address of the server or the
     *  address of a server who knows about this domain.
     *  XXX For now, just use the first address in the list.
     */

    if (local) {
	servAddrPtr = &defaultAddr;
    } else if (defaultPtr->addrList != NULL) {
	servAddrPtr = (struct in_addr *) defaultPtr->addrList[0];
    } else {
	servAddrPtr = (struct in_addr *) defaultPtr->servers[0]->addrList[0];
    }

    result = ERROR;
    if (IsAddr(newServer, &addr)) {
	result = GetHostInfoByAddr(servAddrPtr, &addr, newDefPtr);
	/* If we can't get the name, fall through... */
    } 
    if (result != SUCCESS && result != NONAUTH) {
	result = GetHostInfoByName(servAddrPtr, C_IN, T_A, 
			newServer, newDefPtr, 1);
    }

    /* If we ask for an A record and get none back, but get an NS
       record for the NS server, this is the NONAUTH case.
       We must check whether we got an IP address for the NS
       server or not.  */
    if ((result == SUCCESS || result == NONAUTH) &&
	((newDefPtr->addrList && newDefPtr->addrList[0] != 0) || 
	 (newDefPtr->servers && newDefPtr->servers[0] &&
			newDefPtr->servers[0]->addrList[0] != 0))) {
	    /*
	     *  Found info about the new server. Free the resources for
	     *  the old server.
	     */

	    FreeHostInfoPtr(defaultPtr);
	    free((char *)defaultPtr);
	    defaultPtr = newDefPtr;
	    strcpy(defaultServer, defaultPtr->name);
#ifndef GUI
	    PrintHostInfo(stdout, "Default Server:", defaultPtr);
#else
	    PrintHostInfo(outputfile, "Default Server:", defaultPtr);
#endif
	    return(SUCCESS);
    } else {
#ifndef GUI
	    fprintf(stderr, "*** Can't find address for server %s: %s\n",
		    newServer, DecodeError(result));
#else
	    fprintf(filePtr, "*** Can't find address for server %s: %s\n",
		    newServer, DecodeError(result));
#endif
		    
	    free((char *)newDefPtr);

	    return(result);
    }
}

/*
 ******************************************************************************
 *
 * DoLoookup --
 *
 *	Common subroutine for LookupHost and LookupHostWithServer.
 *
 *  Results:
 *	SUCCESS		- the lookup was successful.
 *	Misc. Errors	- an error message is printed if the lookup failed.
 *
 ******************************************************************************
 */

static int
DoLookup(host, servPtr, serverName)
    char	*host;
    HostInfo	*servPtr;
    char	*serverName;
{
    int result;
    struct in_addr *servAddrPtr;
    struct in_addr addr; 

    /* Skip escape character */
    if (host[0] == '\\')
	host++;

    /*
     *  If the user gives us an address for an address query, 
     *  silently treat it as a PTR query. If the query type is already
     *  PTR, then convert the address into the in-addr.arpa format.
     *
     *  Use the address of the server if it exists, otherwise use the
     *	address of a server who knows about this domain.
     *  XXX For now, just use the first address in the list.
     */

    if (servPtr->addrList != NULL) {
	servAddrPtr = (struct in_addr *) servPtr->addrList[0];
    } else {
	servAddrPtr = (struct in_addr *) servPtr->servers[0]->addrList[0];
    }

    /* 
     * RFC1123 says we "SHOULD check the string syntactically for a 
     * dotted-decimal number before looking it up [...]" (p. 13).
     */
    if (queryType == T_A && IsAddr(host, &addr)) {
	result = GetHostInfoByAddr(servAddrPtr, &addr, &curHostInfo);
    } else {
	if (queryType == T_PTR) {
	    CvtAddrToPtr(host);
	} 
	result = GetHostInfoByName(servAddrPtr, queryClass, queryType, host, 
			&curHostInfo, 0);
    }

    switch (result) {
	case SUCCESS:
	    /*
	     *  If the query was for an address, then the &curHostInfo
	     *  variable can be used by Finger.
	     *  There's no need to print anything for other query types
	     *  because the info has already been printed.
	     */
	    if (queryType == T_A) {
		curHostValid = TRUE;
		PrintHostInfo(filePtr, "Name:", &curHostInfo);
	    }
	    break;

	/*
	 * No Authoritative answer was available but we got names
	 * of servers who know about the host.
	 */
	case NONAUTH:
	    PrintHostInfo(filePtr, "Name:", &curHostInfo);
	    break;

	case NO_INFO:
#ifndef GUI
	    fprintf(stderr, "*** No %s (%s) records available for %s\n", 
			DecodeType(queryType), p_type(queryType), host);
#else
	    fprintf(filePtr, "*** No %s (%s) records available for %s\n", 
			DecodeType(queryType), p_type(queryType), host);
#endif
	    break;

	case TIME_OUT:
	    fprintf(stderr, "*** Request to %s timed-out\n", serverName);
	    break;

	default:
#ifndef GUI
	    fprintf(stderr, "*** %s can't find %s: %s\n", serverName, host,
		    DecodeError(result));
#else
	    fprintf(filePtr, "*** %s can't find %s: %s\n", serverName, host,
		    DecodeError(result));
#endif
    }
    return result;
}

/*
 ******************************************************************************
 *
 *  LookupHost --
 *
 *	Asks the default name server for information about the
 *	specified host or domain. The information is printed
 *	if the lookup was successful.
 *
 *  Results:
 *	ERROR		- the output file could not be opened.
 *	+ results of DoLookup
 *
 ******************************************************************************
 */

int
LookupHost(string, putToFile)
    char	*string;
    Boolean	putToFile;
{
    char	host[NAME_LEN];
    char	file[PATH_MAX];
    int		result;
    FILE *fileptr = NULL;

    /*
     *  Invalidate the current host information to prevent Finger 
     *  from using bogus info.
     */

    curHostValid = FALSE;

    /*
     *	 Parse the command string into the host and
     *	 optional output file name.
     *
     */

    sscanf(string, " %s", host);	/* removes white space */
    if (!putToFile) {

#ifndef GUI	
	filePtr = stdout;
#else
     fileptr = outputfile;
#endif

    } else {
	filePtr = AppOpenFile(string, file);
	if (filePtr == NULL) {
	    fprintf(stderr, "*** Can't open %s for writing\n", file);
	    return(ERROR);
	}
	fprintf(filePtr,"> %s\n", string);
    }

    PrintHostInfo(filePtr, "Server:", defaultPtr);

    result = DoLookup(host, defaultPtr, defaultServer);

    if (putToFile) {
	fclose(filePtr);
	filePtr = NULL;
    }
    return(result);
}

/*
 ******************************************************************************
 *
 *  LookupHostWithServer --
 *
 *	Asks the name server specified in the second argument for 
 *	information about the host or domain specified in the first
 *	argument. The information is printed if the lookup was successful.
 *
 *	Address info about the requested name server is obtained
 *	from the default name server. This routine will return an
 *	error if the default server doesn't have info about the 
 *	requested server. Thus an error return status might not
 *	mean the requested name server doesn't have info about the
 *	requested host.
 *
 *	Comments from LookupHost apply here, too.
 *
 *  Results:
 *	ERROR		- the output file could not be opened.
 *	+ results of DoLookup
 *
 ******************************************************************************
 */

int
LookupHostWithServer(string, putToFile)
    char	*string;
    Boolean	putToFile;
{
    char	file[PATH_MAX];
    char	host[NAME_LEN];
    char	server[NAME_LEN];
    int		result;
    static HostInfo serverInfo;

    curHostValid = FALSE;

    sscanf(string, " %s %s", host, server);
    if (!putToFile) {
#ifndef GUI
	filePtr = stdout;
#else
	filePtr = outputfile;
#endif
    } else {
	filePtr = AppOpenFile(string, file);
	if (filePtr == NULL) {
	    fprintf(stderr, "*** Can't open %s for writing\n", file);
	    return(ERROR);
	}
	fprintf(filePtr,"> %s\n", string);
    }
    
    result = GetHostInfoByName(
		defaultPtr->addrList ?
		    (struct in_addr *) defaultPtr->addrList[0] :
		    (struct in_addr *) defaultPtr->servers[0]->addrList[0], 
		C_IN, T_A, server, &serverInfo, 1);

    if (result != SUCCESS) {
#ifndef GUI
	fprintf(stderr,"*** Can't find address for server %s: %s\n", server,
		 DecodeError(result));