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glibc  2.9
Defines | Functions
res_query.c File Reference
#include <assert.h>
#include <sys/types.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

Go to the source code of this file.

Defines

#define MAXPACKET   65536
#define QUERYSIZE   (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)

Functions

static int __libc_res_nquerydomain (res_state statp, const char *name, const char *domain, int class, int type, u_char *answer, int anslen, u_char **answerp, u_char **answerp2, int *nanswerp2, int *resplen2)
int __libc_res_nquery (res_state statp, const char *name, int class, int type, u_char *answer, int anslen, u_char **answerp, u_char **answerp2, int *nanswerp2, int *resplen2)
 libresolv_hidden_def (__libc_res_nquery)
 libresolv_hidden_def (res_nquery)
 libresolv_hidden_def (__libc_res_nsearch)
 libresolv_hidden_def (res_nsearch)
int res_nquerydomain (res_state statp, const char *name, const char *domain, int class, int type, u_char *answer, int anslen)
 libresolv_hidden_def (res_nquerydomain) const

Define Documentation

#define MAXPACKET   65536

Definition at line 92 of file res_query.c.

#define QUERYSIZE   (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)

Definition at line 95 of file res_query.c.


Function Documentation

int __libc_res_nquery ( res_state  statp,
const char *  name,
int  class,
int  type,
u_char answer,
int  anslen,
u_char **  answerp,
u_char **  answerp2,
int nanswerp2,
int resplen2 
)

Definition at line 114 of file res_query.c.

{
       HEADER *hp = (HEADER *) answer;
       int n, use_malloc = 0;
        u_int oflags = statp->_flags;

       size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE;
       u_char *buf = alloca (bufsize);
       u_char *query1 = buf;
       int nquery1 = -1;
       u_char *query2 = NULL;
       int nquery2 = 0;

 again:
       hp->rcode = NOERROR; /* default */

#ifdef DEBUG
       if (statp->options & RES_DEBUG)
              printf(";; res_query(%s, %d, %d)\n", name, class, type);
#endif

       if (type == T_UNSPEC)
         {
           n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL,
                          query1, bufsize);
           if (n > 0)
             {
              if ((oflags & RES_F_EDNS0ERR) == 0
                  && (statp->options & RES_USE_EDNS0) != 0)
                {
                  n = __res_nopt(statp, n, query1, bufsize, anslen / 2);
                  if (n < 0)
                    goto unspec_nomem;
                }

              nquery1 = n;
              /* Align the buffer.  */
              int npad = ((nquery1 + __alignof__ (HEADER) - 1)
                         & ~(__alignof__ (HEADER) - 1)) - nquery1;
              if (n > bufsize - npad)
                {
                  n = -1;
                  goto unspec_nomem;
                }
              int nused = n + npad;
              query2 = buf + nused;
              n = res_nmkquery(statp, QUERY, name, class, T_AAAA, NULL, 0,
                             NULL, query2, bufsize - nused);
              if (n > 0
                  && (oflags & RES_F_EDNS0ERR) == 0
                  && (statp->options & RES_USE_EDNS0) != 0)
                n = __res_nopt(statp, n, query2, bufsize - nused - n,
                             anslen / 2);
              nquery2 = n;
             }

         unspec_nomem:;
         }
       else
         {
           n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
                          query1, bufsize);

           if (n > 0
              && (oflags & RES_F_EDNS0ERR) == 0
              && (statp->options & RES_USE_EDNS0) != 0)
             n = __res_nopt(statp, n, query1, bufsize, anslen);

           nquery1 = n;
         }

       if (__builtin_expect (n <= 0, 0) && !use_malloc) {
              /* Retry just in case res_nmkquery failed because of too
                 short buffer.  Shouldn't happen.  */
              bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET;
              buf = malloc (bufsize);
              if (buf != NULL) {
                     query1 = buf;
                     use_malloc = 1;
                     goto again;
              }
       }
       if (__builtin_expect (n <= 0, 0)) {
              /* If the query choked with EDNS0, retry without EDNS0.  */
              if ((statp->options & RES_USE_EDNS0) != 0
                  && ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
                     statp->_flags |= RES_F_EDNS0ERR;
#ifdef DEBUG
                     if (statp->options & RES_DEBUG)
                            printf(";; res_nquery: retry without EDNS0\n");
#endif
                        goto again;
              }
#ifdef DEBUG
              if (statp->options & RES_DEBUG)
                     printf(";; res_query: mkquery failed\n");
#endif
              RES_SET_H_ERRNO(statp, NO_RECOVERY);
              if (use_malloc)
                     free (buf);
              return (n);
       }
       assert (answerp == NULL || (void *) *answerp == (void *) answer);
       n = __libc_res_nsend(statp, query1, nquery1, query2, nquery2, answer,
                          anslen, answerp, answerp2, nanswerp2, resplen2);
       if (use_malloc)
              free (buf);
       if (n < 0) {
#ifdef DEBUG
              if (statp->options & RES_DEBUG)
                     printf(";; res_query: send error\n");
#endif
              RES_SET_H_ERRNO(statp, TRY_AGAIN);
              return (n);
       }

       if (answerp != NULL)
         /* __libc_res_nsend might have reallocated the buffer.  */
         hp = (HEADER *) *answerp;

       /* We simplify the following tests by assigning HP to HP2.  It
          is easy to verify that this is the same as ignoring all
          tests of HP2.  */
       HEADER *hp2 = answerp2 ? (HEADER *) *answerp2 : hp;

       if (n < (int) sizeof (HEADER) && answerp2 != NULL
           && *resplen2 > (int) sizeof (HEADER))
         {
           /* Special case of partial answer.  */
           assert (hp != hp2);
           hp = hp2;
         }
       else if (answerp2 != NULL && *resplen2 < (int) sizeof (HEADER)
               && n > (int) sizeof (HEADER))
         {
           /* Special case of partial answer.  */
           assert (hp != hp2);
           hp2 = hp;
         }

       if ((hp->rcode != NOERROR || ntohs(hp->ancount) == 0)
           && (hp2->rcode != NOERROR || ntohs(hp2->ancount) == 0)) {
#ifdef DEBUG
              if (statp->options & RES_DEBUG) {
                     printf(";; rcode = %d, ancount=%d\n", hp->rcode,
                         ntohs(hp->ancount));
                     if (hp != hp2)
                       printf(";; rcode2 = %d, ancount2=%d\n", hp2->rcode,
                             ntohs(hp2->ancount));
              }
#endif
              switch (hp->rcode == NOERROR ? hp2->rcode : hp->rcode) {
              case NXDOMAIN:
                     if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0)
                         || (hp2->rcode == NOERROR
                            && ntohs (hp2->ancount) != 0))
                            goto success;
                     RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
                     break;
              case SERVFAIL:
                     RES_SET_H_ERRNO(statp, TRY_AGAIN);
                     break;
              case NOERROR:
                     if (ntohs (hp->ancount) != 0
                         || ntohs (hp2->ancount) != 0)
                            goto success;
                     RES_SET_H_ERRNO(statp, NO_DATA);
                     break;
              case FORMERR:
              case NOTIMP:
              case REFUSED:
              default:
                     RES_SET_H_ERRNO(statp, NO_RECOVERY);
                     break;
              }
              return (-1);
       }
 success:
       return (n);
}

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static int __libc_res_nquerydomain ( res_state  statp,
const char *  name,
const char *  domain,
int  class,
int  type,
u_char answer,
int  anslen,
u_char **  answerp,
u_char **  answerp2,
int nanswerp2,
int resplen2 
) [static]

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Definition at line 302 of file res_query.c.

{
       return __libc_res_nquery(statp, name, class, type, answer, anslen,
                             NULL, NULL, NULL, NULL);
}

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Definition at line 314 of file res_query.c.

{
       const char *cp, * const *domain;
       HEADER *hp = (HEADER *) answer;
       char tmp[NS_MAXDNAME];
       u_int dots;
       int trailing_dot, ret, saved_herrno;
       int got_nodata = 0, got_servfail = 0, root_on_list = 0;
       int tried_as_is = 0;

       __set_errno (0);
       RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /* True if we never query. */

       dots = 0;
       for (cp = name; *cp != '\0'; cp++)
              dots += (*cp == '.');
       trailing_dot = 0;
       if (cp > name && *--cp == '.')
              trailing_dot++;

       /* If there aren't any dots, it could be a user-level alias. */
       if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
              return (__libc_res_nquery(statp, cp, class, type, answer,
                                     anslen, answerp, answerp2,
                                     nanswerp2, resplen2));

#ifdef DEBUG
       if (statp->options & RES_DEBUG)
              printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n",
                     (int)dots,(int)statp->ndots,(int)trailing_dot,name);
#endif

       /*
        * If there are enough dots in the name, let's just give it a
        * try 'as is'. The threshold can be set with the "ndots" option.
        * Also, query 'as is', if there is a trailing dot in the name.
        */
       saved_herrno = -1;
       if (dots >= statp->ndots || trailing_dot) {
              ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
                                         answer, anslen, answerp,
                                         answerp2, nanswerp2, resplen2);
              if (ret > 0 || trailing_dot)
                     return (ret);
              saved_herrno = h_errno;
              tried_as_is++;
              if (answerp && *answerp != answer) {
                     answer = *answerp;
                     anslen = MAXPACKET;
              }
              if (answerp2
                  && (*answerp2 < answer || *answerp2 >= answer + anslen))
                {
                  free (*answerp2);
                  *answerp2 = NULL;
                }
       }

       /*
        * 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 ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
           (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
              int done = 0;

              for (domain = (const char * const *)statp->dnsrch;
                   *domain && !done;
                   domain++) {

                     if (domain[0][0] == '\0' ||
                         (domain[0][0] == '.' && domain[0][1] == '\0'))
                            root_on_list++;

                     ret = __libc_res_nquerydomain(statp, name, *domain,
                                                class, type,
                                                answer, anslen, answerp,
                                                answerp2, nanswerp2,
                                                resplen2);
                     if (ret > 0)
                            return (ret);

                     if (answerp && *answerp != answer) {
                            answer = *answerp;
                            anslen = MAXPACKET;
                     }
                     if (answerp2
                         && (*answerp2 < answer
                            || *answerp2 >= answer + anslen))
                       {
                         free (*answerp2);
                         *answerp2 = NULL;
                       }

                     /*
                      * 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_DATA 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 (errno == ECONNREFUSED) {
                            RES_SET_H_ERRNO(statp, TRY_AGAIN);
                            return (-1);
                     }

                     switch (statp->res_h_errno) {
                     case NO_DATA:
                            got_nodata++;
                            /* FALLTHROUGH */
                     case HOST_NOT_FOUND:
                            /* keep trying */
                            break;
                     case TRY_AGAIN:
                            if (hp->rcode == SERVFAIL) {
                                   /* try next search element, if any */
                                   got_servfail++;
                                   break;
                            }
                            /* FALLTHROUGH */
                     default:
                            /* anything else implies that we're done */
                            done++;
                     }

                     /* if we got here for some reason other than DNSRCH,
                      * we only wanted one iteration of the loop, so stop.
                      */
                     if ((statp->options & RES_DNSRCH) == 0)
                            done++;
              }
       }

       /*
        * If the name has any dots at all, and no earlier 'as-is' query
        * for the name, and "." is not on the search list, then try an as-is
        * query now.
        */
       if (dots && !(tried_as_is || root_on_list)) {
              ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
                                         answer, anslen, answerp,
                                         answerp2, nanswerp2, resplen2);
              if (ret > 0)
                     return (ret);
       }

       /* if we got here, we didn't satisfy the search.
        * if we did an initial full query, return that query's H_ERRNO
        * (note that we wouldn't be here if that query had succeeded).
        * else if we ever got a nodata, send that back as the reason.
        * else send back meaningless H_ERRNO, that being the one from
        * the last DNSRCH we did.
        */
       if (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen))
         {
           free (*answerp2);
           *answerp2 = NULL;
         }
       if (saved_herrno != -1)
              RES_SET_H_ERRNO(statp, saved_herrno);
       else if (got_nodata)
              RES_SET_H_ERRNO(statp, NO_DATA);
       else if (got_servfail)
              RES_SET_H_ERRNO(statp, TRY_AGAIN);
       return (-1);
}

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libresolv_hidden_def ( __libc_res_nsearch  )

Definition at line 505 of file res_query.c.

{
       return __libc_res_nsearch(statp, name, class, type, answer,
                              anslen, NULL, NULL, NULL, NULL);
}

Definition at line 517 of file res_query.c.

{
       char nbuf[MAXDNAME];
       const char *longname = nbuf;
       int n, d;

#ifdef DEBUG
       if (statp->options & RES_DEBUG)
              printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
                     name, domain?domain:"<Nil>", class, type);
#endif
       if (domain == NULL) {
              /*
               * Check for trailing '.';
               * copy without '.' if present.
               */
              n = strlen(name);
              if (n >= MAXDNAME) {
                     RES_SET_H_ERRNO(statp, NO_RECOVERY);
                     return (-1);
              }
              n--;
              if (n >= 0 && name[n] == '.') {
                     strncpy(nbuf, name, n);
                     nbuf[n] = '\0';
              } else
                     longname = name;
       } else {
              n = strlen(name);
              d = strlen(domain);
              if (n + d + 1 >= MAXDNAME) {
                     RES_SET_H_ERRNO(statp, NO_RECOVERY);
                     return (-1);
              }
              sprintf(nbuf, "%s.%s", name, domain);
       }
       return (__libc_res_nquery(statp, longname, class, type, answer,
                              anslen, answerp, answerp2, nanswerp2,
                              resplen2));
}

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Definition at line 585 of file res_query.c.

                                                                              {
       char *file, *cp1, *cp2;
       char buf[BUFSIZ];
       FILE *fp;

       if (statp->options & RES_NOALIASES)
              return (NULL);
       file = getenv("HOSTALIASES");
       if (file == NULL || (fp = fopen(file, "r")) == NULL)
              return (NULL);
       setbuf(fp, NULL);
       buf[sizeof(buf) - 1] = '\0';
       while (fgets(buf, sizeof(buf), fp)) {
              for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
                     ;
              if (!*cp1)
                     break;
              *cp1 = '\0';
              if (ns_samename(buf, name) == 1) {
                     while (isspace(*++cp1))
                            ;
                     if (!*cp1)
                            break;
                     for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
                            ;
                     *cp2 = '\0';
                     strncpy(dst, cp1, siz - 1);
                     dst[siz - 1] = '\0';
                     fclose(fp);
                     return (dst);
              }
       }
       fclose(fp);
       return (NULL);
}

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int res_nquerydomain ( res_state  statp,
const char *  name,
const char *  domain,
int  class,
int  type,
u_char answer,
int  anslen 
)

Definition at line 575 of file res_query.c.

{
       return __libc_res_nquerydomain(statp, name, domain, class, type,
                                   answer, anslen, NULL, NULL, NULL, NULL);
}

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