host.c

操作系统源代码

	}
	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 = (u8_t *)&answer + n;
	return(printinfo(&answer, eom, T_ANY, 0));
}

static int
printinfo(answer, eom, filter, isls)
	querybuf_t *answer;
	u8_t *eom;
        int filter;
        int isls;
{
	dns_hdr_t *hp;
	u8_t *bp, *cp;
	int n, n1, i, j, nmx, ancount, nscount, arcount, qdcount, buflen;
	u_short pref, class;

	/*
	 * find first satisfactory answer
	 */
	hp = (dns_hdr_t *) answer;
	ancount = ntohs(hp->dh_ancount);
	qdcount = ntohs(hp->dh_qdcount);
	nscount = ntohs(hp->dh_nscount);
	arcount = ntohs(hp->dh_arcount);
	if (_res.options & RES_DEBUG || (verbose && isls == 0))
		printf("rcode = %d (%s), ancount=%d\n", 
		       hp->dh_flag2 & DHF_RCODE,
		       DecodeError(hp->dh_flag2 & DHF_RCODE), ancount);
	if (hp->dh_flag2 & DHF_RCODE != NOERROR || 
		(ancount+nscount+arcount) == 0) {
		switch (hp->dh_flag2 & DHF_RCODE) {
			case NXDOMAIN:
				/* Check if it's an authoritive answer */
				if (hp->dh_flag1 & DHF_AA) {
					h_errno = HOST_NOT_FOUND;
					return(0);
				} else {
					h_errno = TRY_AGAIN;
					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 = (u8_t *)answer + sizeof(dns_hdr_t);
	if (qdcount) {
		cp += dn_skipname((u8_t *)cp,(u8_t *)eom) + QFIXEDSZ;
		while (--qdcount > 0)
			cp += dn_skipname((u8_t *)cp,(u8_t *)eom) + QFIXEDSZ;
	}
	if (ancount) {
	  if (!(hp->dh_flag1 & DHF_AA))
	    if (verbose && isls == 0)
	      printf("The following answer is not authoritative:\n");
	  while (--ancount >= 0 && cp && cp < eom) {
	    cp = pr_rr(cp, (u8_t *)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 = pr_rr(cp, (u8_t *)answer, stdout, filter);
	  }
	}
	if (arcount) {
	  printf("Additional information:\n");
	  while (--arcount >= 0 && cp && cp < eom) {
	    cp = pr_rr(cp, (u8_t *)answer, stdout, filter);
	  }
	}
	return(1);
 }

static u8_t cnamebuf[MAXDNAME];

/*
 * Print resource record fields in human readable form.
 */
static u8_t *
pr_rr(cp, msg, file, filter)
	u8_t *cp, *msg;
	FILE *file;
        int filter;
{
	int type, class, dlen, n, c, proto, ttl;
	ipaddr_t inaddr;
	u8_t *cp1;
	struct protoent *protop;
	struct servent *servp;
	char punc;
	int doprint;
	u8_t name[MAXDNAME];

	if ((cp = 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_long);

	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((char *)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 = 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 = pr_cdname(cp, msg, name, sizeof(name));
		if (doprint)
		  fprintf(file,"\t%s", name);
		cp = 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_long);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;refresh period", _getlong(cp));
		cp += sizeof(u_long);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;retry refresh this often", _getlong(cp));
		cp += sizeof(u_long);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;expiration period", _getlong(cp));
		cp += sizeof(u_long);
		if (doprint)
		  fprintf(file,"\n\t\t\t%ld\t;minimum TTL\n\t\t\t)", _getlong(cp));
		cp += sizeof(u_long);
		break;

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

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

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

	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_long) + 1)
			break;
		bcopy((char *)cp, (char *)&inaddr, sizeof(inaddr));
		cp += sizeof(u_long);
		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 (cp);
}

static	char nbuf[20];

/*
 * Return a string for the type
 */
static 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_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:
		return (sprintf(nbuf, "%d", type) == EOF ? NULL : nbuf);
	}
}

/*
 * Return a mnemonic for class
 */
static char *
pr_class(class)
	int class;
{

	switch (class) {
	case C_IN:		/* internet class */
		return(verbose? " IN" : "");
	case C_HS:		/* internet class */
		return(verbose? " HS" : "");
	case C_ANY:		/* matches any class */
		return(" ANY");
	default:
		return (sprintf(nbuf," %d", class) == EOF ? NULL : nbuf);
	}
}

static u8_t *
pr_cdname(cp, msg, name, namelen)
	u8_t *cp, *msg;
        u8_t *name;
        int namelen;
{
	int n;

	if ((n = dn_expand(msg, msg + 512, cp, name, namelen - 2)) < 0)
		return (NULL);
	if (name[0] == '\0') {
		name[0] = '.';
		name[1] = '\0';
	}
	return (cp + n);
}

char *resultcodes[] = {
	"NOERROR",
	"FORMERR",
	"SERVFAIL",
	"NXDOMAIN",
	"NOTIMP",
	"REFUSED",
	"6",
	"7",
	"8",
	"9",
	"10",
	"11",
	"12",
	"13",
	"14",
	"NOCHANGE",
};



/*
 ******************************************************************************
 *