host.c

早期freebsd实现

		    printf("Aliased to \"%s\"\n", cp);
		_res.options |= RES_DEFNAMES;	  
		return (getdomaininfo(cp, (char *)NULL));
	}
#ifdef MAXDS
	for (nDomain = 0;
	     _res.defdname_list[nDomain][0] != 0;
	     nDomain++) {
	    for (domain = _res.dnsrch_list[nDomain]; *domain; domain++) {
	        if (verbose)
		    printf("Trying domain \"%s\"\n", *domain);
		hp = getdomaininfo(name, *domain);
		if (hp)
			return (hp);
	    }
	}
#else
	for (domain = _res.dnsrch; *domain; domain++) {
	  if (verbose)
	    printf("Trying domain \"%s\"\n", *domain);
	  hp = getdomaininfo(name, *domain);
	  if (hp)
	    return (hp);
	}
#endif
	if (h_errno != HOST_NOT_FOUND ||
	   (_res.options & RES_DNSRCH) == 0)
		return (0);
	if (verbose)
	    printf("Trying null domain\n");
	return (getdomaininfo(name, (char *)NULL));
}

getdomaininfo(name, domain)
	char *name, *domain;
{
  int val1, val2;

  if (gettype)
    return getinfo(name, domain, gettype);
  else {
    val1 = getinfo(name, domain, T_A);
    if (cname || verbose)
      return val1;
    val2 = getinfo(name, domain, T_MX);
    return val1 || val2;
  }
}

getinfo(name, domain, type)
	char *name, *domain;
{

	HEADER *hp;
	char *eom, *bp, *cp;
	querybuf buf, answer;
	int n, n1, i, j, nmx, ancount, nscount, arcount, qdcount, buflen;
	u_short pref, class;
	char host[2*MAXDNAME+2];

	if (domain == NULL)
		(void)sprintf(host, "%.*s", MAXDNAME, name);
	else
		(void)sprintf(host, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain);

	n = res_mkquery(QUERY, host, getclass, type, (char *)NULL, 0, NULL,
		(char *)&buf, sizeof(buf));
	if (n < 0) {
		if (_res.options & RES_DEBUG)
			printf("res_mkquery failed\n");
		h_errno = NO_RECOVERY;
		return(0);
	}
	n = res_send((char *)&buf, n, (char *)&answer, sizeof(answer));
	if (n < 0) {
		if (_res.options & RES_DEBUG)
			printf("res_send failed\n");
		h_errno = TRY_AGAIN;
		return (0);
	}
	eom = (char *)&answer + n;
	return(printinfo(&answer, eom, T_ANY, 0));
      }

printinfo(answer, eom, filter, isls)
	querybuf *answer;
	u_char *eom;
        int filter;
        int isls;
{
	HEADER *hp;
	u_char *bp, *cp;
	int n, n1, i, j, nmx, ancount, nscount, arcount, qdcount, buflen;
	u_short pref, class;

	/*
	 * find first satisfactory answer
	 */
	hp = (HEADER *) answer;
	ancount = ntohs(hp->ancount);
	qdcount = ntohs(hp->qdcount);
	nscount = ntohs(hp->nscount);
	arcount = ntohs(hp->arcount);
	if (_res.options & RES_DEBUG || (verbose && isls == 0))
		printf("rcode = %d (%s), ancount=%d\n", 
		       hp->rcode, DecodeError(hp->rcode), ancount);
	if (hp->rcode != NOERROR || (ancount+nscount+arcount) == 0) {
		switch (hp->rcode) {
			case NXDOMAIN:
				h_errno = HOST_NOT_FOUND;
				return(0);
			case SERVFAIL:
				h_errno = TRY_AGAIN;
				return(0);
#ifdef OLDJEEVES
			/*
			 * Jeeves (TOPS-20 server) still does not
			 * support MX records.  For the time being,
			 * we must accept FORMERRs as the same as
			 * NOERROR.
			 */
			case FORMERR:
#endif /*OLDJEEVES*/
			case NOERROR:
/* TpB - set a return error for this case. NO_DATA */
				h_errno = NO_DATA;
				return(0); /* was 1,but now indicates exception */
#ifndef OLDJEEVES
			case FORMERR:
#endif /*OLDJEEVES*/
			case NOTIMP:
			case REFUSED:
				h_errno = NO_RECOVERY;
				return(0);
		}
		return (0);
	}
	bp = hostbuf;
	nmx = 0;
	buflen = sizeof(hostbuf);
	cp = (u_char *)answer + sizeof(HEADER);
	if (qdcount) {
		cp += dn_skipname(cp, eom) + QFIXEDSZ;
		while (--qdcount > 0)
			cp += dn_skipname(cp, eom) + QFIXEDSZ;
	}
	if (ancount) {
	  if (!hp->aa)
	    if (verbose && isls == 0)
	      printf("The following answer is not authoritative:\n");
	  while (--ancount >= 0 && cp && cp < eom) {
	    cp = (u_char *)pr_rr(cp, answer, stdout, filter);
/*
 * When we ask for address and there is a CNAME, it seems to return
 * both the CNAME and the address.  Since we trace down the CNAME
 * chain ourselves, we don't really want to print the address at
 * this point.
 */
	    if (cname && ! verbose)
	      return (1);
	  }
	}
	if (! verbose)
	  return (1);
	if (nscount) {
	  printf("For authoritative answers, see:\n");
	  while (--nscount >= 0 && cp && cp < eom) {
	    cp = (u_char *)pr_rr(cp, answer, stdout, filter);
	  }
	}
	if (arcount) {
	  printf("Additional information:\n");
	  while (--arcount >= 0 && cp && cp < eom) {
	    cp = (u_char *)pr_rr(cp, answer, stdout, filter);
	  }
	}
	return(1);
 }

static u_char cnamebuf[MAXDNAME];

/*
 * Print resource record fields in human readable form.
 */
char *
pr_rr(cp, msg, file, filter)
	u_char *cp, *msg;
	FILE *file;
        int filter;
{
	int type, class, dlen, n, c, proto, ttl;
	struct in_addr inaddr;
	u_char *cp1;
	struct protoent *protop;
	struct servent *servp;
	char punc;
	int doprint;
	char name[MAXDNAME];

	if ((cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name))) == NULL)
		return (NULL);			/* compression error */

	type = _getshort(cp);
	cp += sizeof(u_short);

	class = _getshort(cp);
	cp += sizeof(u_short);

	ttl = _getlong(cp);
	cp += sizeof(u_int32_t);

	if (filter == type || filter == T_ANY ||
	    (filter == T_A && (type == T_PTR || type == T_NS)))
	  doprint = 1;
	else
	  doprint = 0;

	if (doprint)
	  if (verbose)
	    fprintf(file,"%s\t%d%s\t%s",
		    name, ttl, pr_class(class), pr_type(type));
	  else
	    fprintf(file,"%s%s %s",name, pr_class(class), pr_type(type));
	if (verbose)
	  punc = '\t';
	else
	  punc = ' ';

	dlen = _getshort(cp);
	cp += sizeof(u_short);
	cp1 = cp;
	/*
	 * Print type specific data, if appropriate
	 */
	switch (type) {
	case T_A:
		switch (class) {
		case C_IN:
			bcopy(cp, (char *)&inaddr, sizeof(inaddr));
			if (dlen == 4) {
			        if (doprint)
				  fprintf(file,"%c%s", punc,
					inet_ntoa(inaddr));
				cp += dlen;
			} else if (dlen == 7) {
			        if (doprint) {
				  fprintf(file,"%c%s", punc,
					  inet_ntoa(inaddr));
				  fprintf(file,", protocol = %d", cp[4]);
				  fprintf(file,", port = %d",
					  (cp[5] << 8) + cp[6]);
				}
				cp += dlen;
			}
			break;
		}
		break;
	case T_CNAME:
		if (dn_expand(msg, msg + 512, cp, cnamebuf, 
			      sizeof(cnamebuf)) >= 0)
		  cname = cnamebuf;				
	case T_MB:
#ifdef OLDRR
	case T_MD:
	case T_MF:
#endif /* OLDRR */
	case T_MG:
	case T_MR:
	case T_NS:
	case T_PTR:
		cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
		  fprintf(file,"%c%s",punc, name);
		break;

	case T_HINFO:
		if (n = *cp++) {
			if (doprint)
			  fprintf(file,"%c%.*s", punc, n, cp);
			cp += n;
		}
		if (n = *cp++) {
			if (doprint)
			  fprintf(file,"%c%.*s", punc, n, cp);
			cp += n;
		}
		break;

	case T_SOA:
		cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
		  fprintf(file,"\t%s", name);
		cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
		  fprintf(file," %s", name);
		if (doprint)
		  fprintf(file,"(\n\t\t\t%ld\t;serial (version)", _getlong(cp));
		cp += sizeof(u_int32_t);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;refresh period", _getlong(cp));
		cp += sizeof(u_int32_t);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;retry refresh this often", _getlong(cp));
		cp += sizeof(u_int32_t);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;expiration period", _getlong(cp));
		cp += sizeof(u_int32_t);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;minimum TTL\n\t\t\t)", _getlong(cp));
		cp += sizeof(u_int32_t);
		break;

	case T_MX:
	case T_AFSDB:
		if (doprint)
		  if (verbose)
		    fprintf(file,"\t%ld ",_getshort(cp));
		  else
		    fprintf(file," ");
		cp += sizeof(u_short);
		cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
		  fprintf(file, "%s", name);
		break;

	case T_MINFO:
	case T_RP:
		cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
			fprintf(file, "%c%s", punc, name);
		cp = (u_char *)pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
			fprintf(file, " %s", name);
		break;

	case T_TXT:
		if (doprint)
		  fprintf(file,"%c%.*s", punc, dlen, cp);
		cp += dlen;
		break;

	case T_UINFO:
		if (doprint)
		  fprintf(file,"%c%s", punc, cp);
		cp += dlen;
		break;

	case T_UID:
	case T_GID:
		if (dlen == 4) {
			if (doprint)
			  fprintf(file,"%c%ld", punc, _getlong(cp));
			cp += sizeof(int);
		}
		break;

	case T_WKS:
		if (dlen < sizeof(u_int32_t) + 1)
			break;
		bcopy(cp, (char *)&inaddr, sizeof(inaddr));
		cp += sizeof(u_int32_t);
		proto = *cp++;
		protop = getprotobynumber(proto);
		if (doprint)
		  if (protop)
		    fprintf(file,"%c%s %s", punc,
			    inet_ntoa(inaddr), protop->p_name);
		  else
		    fprintf(file,"%c%s %d", punc,
			    inet_ntoa(inaddr), proto);

		n = 0;
		while (cp < cp1 + dlen) {
			c = *cp++;
			do {
 				if (c & 0200) {
				  servp = NULL;
				  if (protop)
				    servp = getservbyport (htons(n),
							   protop->p_name);
				  if (doprint)
				    if (servp)
				      fprintf(file, " %s", servp->s_name);
				    else
				      fprintf(file, " %d", n);
				}
 				c <<= 1;
			} while (++n & 07);
		}
		break;

	default:
		if (doprint)
		  fprintf(file,"%c???", punc);
		cp += dlen;
	}
	if (cp != cp1 + dlen)
		fprintf(file,"packet size error (%#x != %#x)\n", cp, cp1+dlen);
	if (doprint)
	  fprintf(file,"\n");
	return (char *)cp;
}

static	char nbuf[20];

/*
 * Return a string for the type
 */
char *
pr_type(type)
	int type;
{
	switch (type) {
	case T_A:
		return(verbose? "A" : "has address");
	case T_NS:		/* authoritative server */
		return("NS");
#ifdef OLDRR
	case T_MD:		/* mail destination */
		return("MD");
	case T_MF:		/* mail forwarder */
		return("MF");
#endif /* OLDRR */
	case T_CNAME:		/* connonical name */
		return(verbose? "CNAME" : "is a nickname for");
	case T_SOA:		/* start of authority zone */
		return("SOA");
	case T_MB:		/* mailbox domain name */
		return("MB");
	case T_MG:		/* mail group member */
		return("MG");
	case T_MX:		/* mail routing info */
		return(verbose? "MX" : "mail is handled by");
	/* Roy start */
	case T_TXT:		/* TXT - descriptive info */
		return(verbose? "TXT" : "descriptive text");
	/* Roy end */
	case T_AFSDB:		/* AFS/DCE info */
		return(verbose? "AFSDB" : "DCE or AFS service from");
	case T_MR:		/* mail rename name */
		return("MR");
	case T_NULL:		/* null resource record */
		return("NULL");
	case T_WKS:		/* well known service */
		return("WKS");
	case T_PTR:		/* domain name pointer */
		return("PTR");
	case T_HINFO:		/* host information */
		return("HINFO");
	case T_MINFO:		/* mailbox information */
		return("MINFO");
	case T_AXFR:		/* zone transfer */
		return("AXFR");
	case T_MAILB:		/* mail box */
		return("MAILB");
	case T_MAILA:		/* mail address */
		return("MAILA");
	case T_ANY:		/* matches any type */
		return("ANY");
	case T_UINFO:
		return("UINFO");
	case T_UID:
		return("UID");
	case T_GID:
		return("GID");
	default:
		sprintf(nbuf, "%d", type);
		return nbuf;
	}
}