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Annotation of 43BSDTahoe/lib/libc/net/res_query.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1988 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that this notice is preserved and that due credit is given
        !             7:  * to the University of California at Berkeley. The name of the University
        !             8:  * may not be used to endorse or promote products derived from this
        !             9:  * software without specific prior written permission. This software
        !            10:  * is provided ``as is'' without express or implied warranty.
        !            11:  */
        !            12: 
        !            13: #if defined(LIBC_SCCS) && !defined(lint)
        !            14: static char sccsid[] = "@(#)res_query.c        5.4 (Berkeley) 4/21/88";
        !            15: #endif /* LIBC_SCCS and not lint */
        !            16: 
        !            17: #include <sys/param.h>
        !            18: #include <sys/socket.h>
        !            19: #include <netinet/in.h>
        !            20: #include <ctype.h>
        !            21: #include <netdb.h>
        !            22: #include <stdio.h>
        !            23: #include <errno.h>
        !            24: #include <strings.h>
        !            25: #include <arpa/inet.h>
        !            26: #include <arpa/nameser.h>
        !            27: #include <resolv.h>
        !            28: 
        !            29: #if PACKETSZ > 1024
        !            30: #define MAXPACKET      PACKETSZ
        !            31: #else
        !            32: #define MAXPACKET      1024
        !            33: #endif
        !            34: 
        !            35: extern int errno;
        !            36: int h_errno;
        !            37: 
        !            38: /*
        !            39:  * Formulate a normal query, send, and await answer.
        !            40:  * Returned answer is placed in supplied buffer "answer".
        !            41:  * Perform preliminary check of answer, returning success only
        !            42:  * if no error is indicated and the answer count is nonzero.
        !            43:  * Return the size of the response on success, -1 on error.
        !            44:  * Error number is left in h_errno.
        !            45:  * Caller must parse answer and determine whether it answers the question.
        !            46:  */
        !            47: res_query(name, class, type, answer, anslen)
        !            48:        char *name;             /* domain name */
        !            49:        int class, type;        /* class and type of query */
        !            50:        u_char *answer;         /* buffer to put answer */
        !            51:        int anslen;             /* size of answer buffer */
        !            52: {
        !            53:        char buf[MAXPACKET];
        !            54:        HEADER *hp;
        !            55:        int n;
        !            56: 
        !            57:        if ((_res.options & RES_INIT) == 0 && res_init() == -1)
        !            58:                return (-1);
        !            59: #ifdef DEBUG
        !            60:        if (_res.options & RES_DEBUG)
        !            61:                printf("res_query(%s, %d, %d)\n", name, class, type);
        !            62: #endif
        !            63:        n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL,
        !            64:            buf, sizeof(buf));
        !            65: 
        !            66:        if (n <= 0) {
        !            67: #ifdef DEBUG
        !            68:                if (_res.options & RES_DEBUG)
        !            69:                        printf("res_query: mkquery failed\n");
        !            70: #endif
        !            71:                h_errno = NO_RECOVERY;
        !            72:                return (n);
        !            73:        }
        !            74:        n = res_send(buf, n, answer, anslen);
        !            75:        if (n < 0) {
        !            76: #ifdef DEBUG
        !            77:                if (_res.options & RES_DEBUG)
        !            78:                        printf("res_query: send error\n");
        !            79: #endif
        !            80:                h_errno = TRY_AGAIN;
        !            81:                return(n);
        !            82:        }
        !            83: 
        !            84:        hp = (HEADER *) answer;
        !            85:        if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
        !            86: #ifdef DEBUG
        !            87:                if (_res.options & RES_DEBUG)
        !            88:                        printf("rcode = %d, ancount=%d\n", hp->rcode,
        !            89:                            ntohs(hp->ancount));
        !            90: #endif
        !            91:                switch (hp->rcode) {
        !            92:                        case NXDOMAIN:
        !            93:                                h_errno = HOST_NOT_FOUND;
        !            94:                                break;
        !            95:                        case SERVFAIL:
        !            96:                                h_errno = TRY_AGAIN;
        !            97:                                break;
        !            98:                        case NOERROR:
        !            99:                                h_errno = NO_DATA;
        !           100:                                break;
        !           101:                        case FORMERR:
        !           102:                        case NOTIMP:
        !           103:                        case REFUSED:
        !           104:                        default:
        !           105:                                h_errno = NO_RECOVERY;
        !           106:                                break;
        !           107:                }
        !           108:                return (-1);
        !           109:        }
        !           110:        return(n);
        !           111: }
        !           112: 
        !           113: /*
        !           114:  * Formulate a normal query, send, and retrieve answer in supplied buffer.
        !           115:  * Return the size of the response on success, -1 on error.
        !           116:  * If enabled, implement search rules until answer or unrecoverable failure
        !           117:  * is detected.  Error number is left in h_errno.
        !           118:  * Only useful for queries in the same name hierarchy as the local host
        !           119:  * (not, for example, for host address-to-name lookups in domain in-addr.arpa).
        !           120:  */
        !           121: res_search(name, class, type, answer, anslen)
        !           122:        char *name;             /* domain name */
        !           123:        int class, type;        /* class and type of query */
        !           124:        u_char *answer;         /* buffer to put answer */
        !           125:        int anslen;             /* size of answer */
        !           126: {
        !           127:        register char *cp, **domain;
        !           128:        int n, ret, got_nodata = 0;
        !           129:        char *hostalias();
        !           130: 
        !           131:        if ((_res.options & RES_INIT) == 0 && res_init() == -1)
        !           132:                return (-1);
        !           133: 
        !           134:        errno = 0;
        !           135:        h_errno = HOST_NOT_FOUND;               /* default, if we never query */
        !           136:        for (cp = name, n = 0; *cp; cp++)
        !           137:                if (*cp == '.')
        !           138:                        n++;
        !           139:        if (n == 0 && (cp = hostalias(name)))
        !           140:                return (res_query(cp, class, type, answer, anslen));
        !           141: 
        !           142:        if ((n == 0 || *--cp != '.') && (_res.options & RES_DEFNAMES))
        !           143:            for (domain = _res.dnsrch; *domain; domain++) {
        !           144:                ret = res_querydomain(name, *domain, class, type,
        !           145:                    answer, anslen);
        !           146:                if (ret > 0)
        !           147:                        return (ret);
        !           148:                /*
        !           149:                 * If no server present, give up.
        !           150:                 * If name isn't found in this domain,
        !           151:                 * keep trying higher domains in the search list
        !           152:                 * (if that's enabled).
        !           153:                 * On a NO_DATA error, keep trying, otherwise
        !           154:                 * a wildcard entry of another type could keep us
        !           155:                 * from finding this entry higher in the domain.
        !           156:                 * If we get some other error (non-authoritative negative
        !           157:                 * answer or server failure), then stop searching up,
        !           158:                 * but try the input name below in case it's fully-qualified.
        !           159:                 */
        !           160:                if (errno == ECONNREFUSED) {
        !           161:                        h_errno = TRY_AGAIN;
        !           162:                        return (-1);
        !           163:                }
        !           164:                if (h_errno == NO_DATA)
        !           165:                        got_nodata++;
        !           166:                if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) ||
        !           167:                    (_res.options & RES_DNSRCH) == 0)
        !           168:                        break;
        !           169:        }
        !           170:        /*
        !           171:         * If the search/default failed, try the name as fully-qualified,
        !           172:         * but only if it contained at least one dot (even trailing).
        !           173:         */
        !           174:        if (n)
        !           175:                return (res_querydomain(name, (char *)NULL, class, type,
        !           176:                    answer, anslen));
        !           177:        if (got_nodata)
        !           178:                h_errno = NO_DATA;
        !           179:        return (-1);
        !           180: }
        !           181: 
        !           182: /*
        !           183:  * Perform a call on res_query on the concatenation of name and domain,
        !           184:  * removing a trailing dot from name if domain is NULL.
        !           185:  */
        !           186: res_querydomain(name, domain, class, type, answer, anslen)
        !           187:        char *name, *domain;
        !           188:        int class, type;        /* class and type of query */
        !           189:        u_char *answer;         /* buffer to put answer */
        !           190:        int anslen;             /* size of answer */
        !           191: {
        !           192:        char nbuf[2*MAXDNAME+2];
        !           193:        char *longname = nbuf;
        !           194:        int n;
        !           195: 
        !           196: #ifdef DEBUG
        !           197:        if (_res.options & RES_DEBUG)
        !           198:                printf("res_querydomain(%s, %s, %d, %d)\n",
        !           199:                    name, domain, class, type);
        !           200: #endif
        !           201:        if (domain == NULL) {
        !           202:                /*
        !           203:                 * Check for trailing '.';
        !           204:                 * copy without '.' if present.
        !           205:                 */
        !           206:                n = strlen(name) - 1;
        !           207:                if (name[n] == '.' && n < sizeof(nbuf) - 1) {
        !           208:                        bcopy(name, nbuf, n);
        !           209:                        nbuf[n] = '\0';
        !           210:                } else
        !           211:                        longname = name;
        !           212:        } else
        !           213:                (void)sprintf(nbuf, "%.*s.%.*s",
        !           214:                    MAXDNAME, name, MAXDNAME, domain);
        !           215: 
        !           216:        return (res_query(longname, class, type, answer, anslen));
        !           217: }
        !           218: 
        !           219: char *
        !           220: hostalias(name)
        !           221:        register char *name;
        !           222: {
        !           223:        register char *C1, *C2;
        !           224:        FILE *fp;
        !           225:        char *file, *getenv(), *strcpy(), *strncpy();
        !           226:        char buf[BUFSIZ];
        !           227:        static char abuf[MAXDNAME];
        !           228: 
        !           229:        file = getenv("HOSTALIASES");
        !           230:        if (file == NULL || (fp = fopen(file, "r")) == NULL)
        !           231:                return (NULL);
        !           232:        buf[sizeof(buf) - 1] = '\0';
        !           233:        while (fgets(buf, sizeof(buf), fp)) {
        !           234:                for (C1 = buf; *C1 && !isspace(*C1); ++C1);
        !           235:                if (!*C1)
        !           236:                        break;
        !           237:                *C1 = '\0';
        !           238:                if (!strcasecmp(buf, name)) {
        !           239:                        while (isspace(*++C1));
        !           240:                        if (!*C1)
        !           241:                                break;
        !           242:                        for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2);
        !           243:                        abuf[sizeof(abuf) - 1] = *C2 = '\0';
        !           244:                        (void)strncpy(abuf, C1, sizeof(abuf) - 1);
        !           245:                        fclose(fp);
        !           246:                        return (abuf);
        !           247:                }
        !           248:        }
        !           249:        fclose(fp);
        !           250:        return (NULL);
        !           251: }

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