getinfo.c

一个可用的dns服务器源代码

		Boolean	found;

		n = dn_expand(answer.qb2, eom, cp, (char *)bp, buflen);
		if (n < 0) {
		    return(ERROR);
		}
		cp += n;
		len = strlen((char *)bp) + 1;
		namePtr = Calloc(1, len); /* server host name */
		bcopy(bp, namePtr, len);

		/*
		 * Store the information keyed by the server host name.
		 */
		found = FALSE;
		for (j = 0; j < numServers; j++) {
		    if (strcmp(namePtr, server[j].name) == 0) {
			found = TRUE;
			free(namePtr);
			break;
		    }
		}
		if (found) {
		    server[j].numDomains++;
		    if (server[j].numDomains <= MAXDOMAINS) {
			server[j].domain[server[j].numDomains-1] = dnamePtr;
		    }
		} else {
		    if (numServers >= MAXSERVERS) {
			break;
		    }
		    server[numServers].name = namePtr;
		    server[numServers].domain[0] = dnamePtr;
		    server[numServers].numDomains = 1;
		    server[numServers].numAddresses = 0;
		    numServers++;
		}
	    }
	}
    }

    /*
     * Additional resource records contain addresses of servers.
     */
    cp = (u_char *)res_skip((char *) &answer, 3, eom);

    if (queryType != T_A) {
	/*
	 * If we don't need to save the record, just print it.
	 */
	while (--arcount >= 0 && cp < eom) {
	    if ((cp = (u_char *)Print_rr(cp,
		(char *) &answer, eom, filePtr)) == NULL) {
		return(ERROR);
	    }
	}
    } else {
	while (--arcount >= 0 && cp < eom) {
	    n = dn_expand(answer.qb2, eom, cp, (char *)bp, buflen);
	    if (n < 0) {
		break;
	    }
	    cp   += n;
	    type  = GetShort(cp);
	    class = GetShort(cp);
	    cp   += INT32SZ;	/* skip TTL */
	    dlen  = GetShort(cp);

	    if (type != T_A)  {
		cp += dlen;
		continue;
	    } else {
		for (j = 0; j < numServers; j++) {
		    if (strcmp((char *)bp, server[j].name) == 0) {
			server[j].numAddresses++;
			if (server[j].numAddresses <= MAXADDRS) {
			    server[j].address[server[j].numAddresses-1] = 
				    				Calloc(1,dlen);
			    bcopy(cp,
			      server[j].address[server[j].numAddresses-1],dlen);
			    break;
			}
		    }
		}
		cp += dlen;
	    }
	}
    }

    /*
     * If we are returning name server info, transfer it to the hostPtr.
     */
    if (numServers > 0) {
	hostPtr->servers = (ServerInfo **)
				Calloc(numServers+1, sizeof(ServerInfo *));

	for (i = 0; i < numServers; i++) {
	    hostPtr->servers[i] = (ServerInfo *) Calloc(1, sizeof(ServerInfo));
	    hostPtr->servers[i]->name = server[i].name;


	    hostPtr->servers[i]->domains = (char **)
				Calloc(server[i].numDomains+1,sizeof(char *));
	    for (j = 0; j < server[i].numDomains; j++) {
		hostPtr->servers[i]->domains[j] = server[i].domain[j];
	    }
	    hostPtr->servers[i]->domains[j] = NULL;


	    hostPtr->servers[i]->addrList = (char **)
				Calloc(server[i].numAddresses+1,sizeof(char *));
	    for (j = 0; j < server[i].numAddresses; j++) {
		hostPtr->servers[i]->addrList[j] = server[i].address[j];
	    }
	    hostPtr->servers[i]->addrList[j] = NULL;

	}
	hostPtr->servers[i] = NULL;
    }

    switch (queryType) {
	case T_A:
		return NONAUTH;
	case T_PTR:
		if (iquery)
			return NO_INFO;
		/* fall through */
	default:
		return SUCCESS;
    }
}

/*
*******************************************************************************
*
*  GetHostInfo --
*
*	Retrieves host name, address and alias information
*	for a domain.
*
*	Algorithm from res_search().
*
*  Results:
*	ERROR		- res_mkquery failed.
*	+ return values from GetAnswer()
*
*******************************************************************************
*/

int
GetHostInfoByName(nsAddrPtr, queryClass, queryType, name, hostPtr, isServer)
    struct in_addr	*nsAddrPtr;
    int			queryClass;
    int			queryType;
    char		*name;
    HostInfo		*hostPtr;
    Boolean		isServer;
{
    int			n;
    register int	result;
    register char	**domain;
    const char		*cp;
    Boolean		got_nodata = FALSE;
    struct in_addr	ina;
    Boolean		tried_as_is = FALSE;

    /* Catch explicit addresses */
    if ((queryType == T_A) && IsAddr(name, &ina)) {
	hostPtr->name = Calloc(strlen(name)+3, 1);
	(void)sprintf(hostPtr->name,"[%s]",name);
	hostPtr->aliases = NULL;
	hostPtr->servers = NULL;
	hostPtr->addrType = AF_INET;
	hostPtr->addrLen = INADDRSZ;
	hostPtr->addrList = (char **)Calloc(2, sizeof(char *));
	hostPtr->addrList[0] = Calloc(INT32SZ, sizeof(char));
	bcopy((char *)&ina, hostPtr->addrList[0], INADDRSZ);
	hostPtr->addrList[1] = NULL;
	return(SUCCESS);
    }

    result = NXDOMAIN;
    for (cp = name, n = 0; *cp; cp++)
	    if (*cp == '.')
		    n++;
    if (n == 0 && (cp = hostalias(name))) {
#ifndef GUI
	    printf("Aliased to \"%s\"\n\n", cp);
#else
	    fprintf(outputfile,"Aliased to \"%s\"\n\n", cp);
#endif
	    return (GetHostDomain(nsAddrPtr, queryClass, queryType,
		    (char *)cp, (char *)NULL, hostPtr, isServer));
    }

    /*
     * If there are dots in the name already, let's just give it a try
     * 'as is'.  The threshold can be set with the "ndots" option.
     */
    if (n >= (int)_res.ndots) {
	    result = GetHostDomain(nsAddrPtr, queryClass, queryType,
				   name, (char *)NULL, hostPtr, isServer);
            if (result == SUCCESS)
	        return (result);
	    if (result == NO_INFO)
		got_nodata++;
            tried_as_is++;
    }

    /*
     * We do at least one level of search if
     *	- there is no dot and RES_DEFNAME is set, or
     *	- there is at least one dot, there is no trailing dot,
     *	  and RES_DNSRCH is set.
     */
    if ((n == 0 && _res.options & RES_DEFNAMES) ||
       (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH))
	 for (domain = _res.dnsrch; *domain; domain++) {
	    result = GetHostDomain(nsAddrPtr, queryClass, queryType,
		    name, *domain, hostPtr, isServer);
	    /*
	     * If no server present, give up.
	     * If name isn't found in this domain,
	     * keep trying higher domains in the search list
	     * (if that's enabled).
	     * On a NO_INFO error, keep trying, otherwise
	     * a wildcard entry of another type could keep us
	     * from finding this entry higher in the domain.
	     * If we get some other error (negative answer or
	     * server failure), then stop searching up,
	     * but try the input name below in case it's fully-qualified.
	     */
	    if (result == SUCCESS || result == NO_RESPONSE)
		    return result;
	    if (result == NO_INFO)
		    got_nodata++;
	    if ((result != NXDOMAIN && result != NO_INFO) ||
		(_res.options & RES_DNSRCH) == 0)
		    break;
    }
    /* if we have not already tried the name "as is", do that now.
     * note that we do this regardless of how many dots were in the
     * name or whether it ends with a dot.
     */
    if (!tried_as_is &&
	(result = GetHostDomain(nsAddrPtr, queryClass, queryType,
				name, (char *)NULL, hostPtr, isServer)
	 ) == SUCCESS)
	    return (result);
    if (got_nodata)
	result = NO_INFO;
    return (result);
}

/*
 * Perform a query on the concatenation of name and domain,
 * removing a trailing dot from name if domain is NULL.
 */
int
GetHostDomain(nsAddrPtr, queryClass, queryType, name, domain, hostPtr, isServer)
    struct in_addr	*nsAddrPtr;
    int			queryClass;
    int			queryType;
    char		*name, *domain;
    HostInfo		*hostPtr;
    Boolean		isServer;
{
    querybuf buf;
    char nbuf[2*MAXDNAME+2];
    char *longname = nbuf;
    int n;

    if (domain == NULL) {
	    /*
	     * Check for trailing '.';
	     * copy without '.' if present.
	     */
	    n = strlen(name) - 1;
	    if (name[n] == '.' && n < sizeof(nbuf) - 1) {
		    bcopy(name, nbuf, n);
		    nbuf[n] = '\0';
	    } else
		    longname = name;
    } else {
	    (void)sprintf(nbuf, "%.*s.%.*s",
		    MAXDNAME, name, MAXDNAME, domain);
	    longname = nbuf;
    }
    n = res_mkquery(QUERY, longname, queryClass, queryType,
		    NULL, 0, 0, buf.qb2, sizeof(buf));
    if (n < 0) {
	if (_res.options & RES_DEBUG) {
	    printf("Res_mkquery failed\n");
	}
	return (ERROR);
    }

    n = GetAnswer(nsAddrPtr, queryType, (char *)&buf, n, 0, hostPtr, isServer);

    /*
     * GetAnswer didn't find a name, so set it to the specified one.
     */
    if (n == NONAUTH) {
	if (hostPtr->name == NULL) {
	    int len = strlen(longname) + 1;
	    hostPtr->name = Calloc(len, sizeof(char));
	    bcopy(longname, hostPtr->name, len);
	}
    }
    return(n);
}


/*
*******************************************************************************
*
*  GetHostInfoByAddr --
*
*	Performs a PTR lookup in in-addr.arpa to find the host name
*	that corresponds to the given address.
*
*  Results:
*	ERROR		- res_mkquery failed.
*	+ return values from GetAnswer()
*
*******************************************************************************
*/

int
GetHostInfoByAddr(nsAddrPtr, address, hostPtr)
    struct in_addr	*nsAddrPtr;
    struct in_addr	*address;
    HostInfo		*hostPtr;
{
    int		n;
    querybuf	buf;
    char	qbuf[MAXDNAME];
    char	*p = (char *) &address->s_addr;

    (void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
	    ((unsigned)p[3] & 0xff),
	    ((unsigned)p[2] & 0xff),
	    ((unsigned)p[1] & 0xff),
	    ((unsigned)p[0] & 0xff));
    n = res_mkquery(QUERY, qbuf, C_IN, T_PTR, NULL, 0, NULL,
		    buf.qb2, sizeof buf);
    if (n < 0) {
	if (_res.options & RES_DEBUG) {
	    printf("res_mkquery() failed\n");
	}
	return (ERROR);
    }
    n = GetAnswer(nsAddrPtr, T_PTR, (char *) &buf, n, 1, hostPtr, 1);
    if (n == SUCCESS) {
	hostPtr->addrType = AF_INET;
	hostPtr->addrLen = 4;
	hostPtr->addrList = (char **)Calloc(2, sizeof(char *));
	hostPtr->addrList[0] = Calloc(INT32SZ, sizeof(char));
	bcopy((char *)p, hostPtr->addrList[0], INADDRSZ);
	hostPtr->addrList[1] = NULL;
    }
    return n;
}

/*
*******************************************************************************
*
*  FreeHostInfoPtr --
*
*	Deallocates all the calloc'd areas for a HostInfo variable.
*
*******************************************************************************
*/

void
FreeHostInfoPtr(hostPtr)
    register HostInfo *hostPtr;
{
    int i, j;

    if (hostPtr->name != NULL) {
	free(hostPtr->name);
	hostPtr->name = NULL;
    }

    if (hostPtr->aliases != NULL) {
	i = 0;
	while (hostPtr->aliases[i] != NULL) {
	    free(hostPtr->aliases[i]);
	    i++;
	}
	free((char *)hostPtr->aliases);
	hostPtr->aliases = NULL;
    }

    if (hostPtr->addrList != NULL) {
	i = 0;
	while (hostPtr->addrList[i] != NULL) {
	    free(hostPtr->addrList[i]);
	    i++;
	}
	free((char *)hostPtr->addrList);
	hostPtr->addrList = NULL;
    }

    if (hostPtr->servers != NULL) {
	i = 0;
	while (hostPtr->servers[i] != NULL) {

	    if (hostPtr->servers[i]->name != NULL) {
		free(hostPtr->servers[i]->name);
	    }

	    if (hostPtr->servers[i]->domains != NULL) {
		j = 0;
		while (hostPtr->servers[i]->domains[j] != NULL) {
		    free(hostPtr->servers[i]->domains[j]);
		    j++;
		}
		free((char *)hostPtr->servers[i]->domains);
	    }

	    if (hostPtr->servers[i]->addrList != NULL) {
		j = 0;
		while (hostPtr->servers[i]->addrList[j] != NULL) {
		    free(hostPtr->servers[i]->addrList[j]);
		    j++;
		}
		free((char *)hostPtr->servers[i]->addrList);
	    }
	    free((char *)hostPtr->servers[i]);
	    i++;
	}
	free((char *)hostPtr->servers);
	hostPtr->servers = NULL;
    }
}