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glibc  2.9
Typedefs | Functions | Variables
aicache.c File Reference
#include <assert.h>
#include <errno.h>
#include <libintl.h>
#include <netdb.h>
#include <nss.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/mman.h>
#include "dbg_log.h"
#include "nscd.h"

Go to the source code of this file.

Typedefs

typedef enum nss_status(* nss_gethostbyname4_r )(const char *name, struct gaih_addrtuple **pat, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp)
typedef enum nss_status(* nss_gethostbyname3_r )(const char *name, int af, struct hostent *host, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *, char **)
typedef enum nss_status(* nss_getcanonname_r )(const char *name, char *buffer, size_t buflen, char **result, int *errnop, int *h_errnop)

Functions

static void addhstaiX (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid, struct hashentry *he, struct datahead *dh)
void addhstai (struct database_dyn *db, int fd, request_header *req, void *key, uid_t uid)
void readdhstai (struct database_dyn *db, struct hashentry *he, struct datahead *dh)

Variables

static const ai_response_header notfound

Typedef Documentation

typedef enum nss_status(* nss_getcanonname_r)(const char *name, char *buffer, size_t buflen, char **result, int *errnop, int *h_errnop)

Definition at line 46 of file aicache.c.

typedef enum nss_status(* nss_gethostbyname3_r)(const char *name, int af, struct hostent *host, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *, char **)

Definition at line 42 of file aicache.c.

typedef enum nss_status(* nss_gethostbyname4_r)(const char *name, struct gaih_addrtuple **pat, char *buffer, size_t buflen, int *errnop, int *h_errnop, int32_t *ttlp)

Definition at line 38 of file aicache.c.


Function Documentation

void addhstai ( struct database_dyn db,
int  fd,
request_header req,
void *  key,
uid_t  uid 
)

Definition at line 573 of file aicache.c.

{
  addhstaiX (db, fd, req, key, uid, NULL, NULL);
}

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static void addhstaiX ( struct database_dyn db,
int  fd,
request_header req,
void *  key,
uid_t  uid,
struct hashentry he,
struct datahead dh 
) [static]

Definition at line 62 of file aicache.c.

{
  /* Search for the entry matching the key.  Please note that we don't
     look again in the table whether the dataset is now available.  We
     simply insert it.  It does not matter if it is in there twice.  The
     pruning function only will look at the timestamp.  */

  /* We allocate all data in one memory block: the iov vector,
     the response header and the dataset itself.  */
  struct dataset
  {
    struct datahead head;
    ai_response_header resp;
    char strdata[0];
  } *dataset = NULL;

  if (__builtin_expect (debug_level > 0, 0))
    {
      if (he == NULL)
       dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key);
      else
       dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key);
    }

  static service_user *hosts_database;
  service_user *nip = NULL;
  int no_more;
  int rc6 = 0;
  int rc4 = 0;
  int herrno = 0;

  if (hosts_database != NULL)
    {
      nip = hosts_database;
      no_more = 0;
    }
  else
    no_more = __nss_database_lookup ("hosts", NULL,
                                 "dns [!UNAVAIL=return] files", &nip);

  if (__res_maybe_init (&_res, 0) == -1)
           no_more = 1;

  /* If we are looking for both IPv4 and IPv6 address we don't want
     the lookup functions to automatically promote IPv4 addresses to
     IPv6 addresses.  Currently this is decided by setting the
     RES_USE_INET6 bit in _res.options.  */
  int old_res_options = _res.options;
  _res.options &= ~RES_USE_INET6;

  size_t tmpbuf6len = 512;
  char *tmpbuf6 = alloca (tmpbuf6len);
  size_t tmpbuf4len = 0;
  char *tmpbuf4 = NULL;
  int32_t ttl = INT32_MAX;
  ssize_t total = 0;
  char *key_copy = NULL;
  bool alloca_used = false;

  while (!no_more)
    {
      void *cp;
      int status[2] = { NSS_STATUS_UNAVAIL, NSS_STATUS_UNAVAIL };
      int naddrs = 0;
      size_t addrslen = 0;
      char *canon = NULL;
      size_t canonlen;

      nss_gethostbyname4_r fct4 = __nss_lookup_function (nip,
                                                  "gethostbyname4_r");
      if (fct4 != NULL)
       {
         struct gaih_addrtuple *at = NULL;
         while (1)
           {
             rc6 = 0;
             herrno = 0;
             status[1] = DL_CALL_FCT (fct4, (key, &at, tmpbuf6, tmpbuf6len,
                                         &rc6, &herrno, &ttl));
             if (rc6 != ERANGE || (herrno != NETDB_INTERNAL
                                && herrno != TRY_AGAIN))
              break;
             tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
           }

         if (rc6 != 0 && herrno == NETDB_INTERNAL)
           goto out;

         if (status[1] != NSS_STATUS_SUCCESS)
           goto next_nip;

         /* We found the data.  Count the addresses and the size.  */
         for (const struct gaih_addrtuple *at2 = at; at2 != NULL;
              at2 = at2->next)
           {
             ++naddrs;
             /* We do not handle anything other than IPv4 and IPv6
               addresses.  The getaddrinfo implementation does not
               either so it is not worth trying to do more.  */
             if (at2->family == AF_INET)
              addrslen += INADDRSZ;
             else if (at2->family == AF_INET6)
              addrslen += IN6ADDRSZ;
           }
         canon = at->name;
         canonlen = strlen (canon) + 1;

         total = sizeof (*dataset) + naddrs + addrslen + canonlen;

         /* Now we can allocate the data structure.  If the TTL of the
            entry is reported as zero do not cache the entry at all.  */
         if (ttl != 0 && he == NULL)
           {
             dataset = (struct dataset *) mempool_alloc (db, total
                                                   + req->key_len,
                                                   IDX_result_data);
             if (dataset == NULL)
              ++db->head->addfailed;
           }

         if (dataset == NULL)
           {
             /* We cannot permanently add the result in the moment.  But
               we can provide the result as is.  Store the data in some
               temporary memory.  */
             dataset = (struct dataset *) alloca (total + req->key_len);

             /* We cannot add this record to the permanent database.  */
             alloca_used = true;
           }

         /* Fill in the address and address families.  */
         char *addrs = dataset->strdata;
         uint8_t *family = (uint8_t *) (addrs + addrslen);

         for (const struct gaih_addrtuple *at2 = at; at2 != NULL;
              at2 = at2->next)
           {
             *family++ = at2->family;
             if (at2->family == AF_INET)
              addrs = mempcpy (addrs, at2->addr, INADDRSZ);
             else if (at2->family == AF_INET6)
              addrs = mempcpy (addrs, at2->addr, IN6ADDRSZ);
           }

         cp = family;
       }
      else
       {
         /* Prefer the function which also returns the TTL and
            canonical name.  */
         nss_gethostbyname3_r fct = __nss_lookup_function (nip,
                                                     "gethostbyname3_r");
         if (fct == NULL)
           fct = __nss_lookup_function (nip, "gethostbyname2_r");

         if (fct == NULL)
           goto next_nip;

         struct hostent th[2];

         /* Collect IPv6 information first.  */
         while (1)
           {
             rc6 = 0;
             status[0] = DL_CALL_FCT (fct, (key, AF_INET6, &th[0], tmpbuf6,
                                        tmpbuf6len, &rc6, &herrno, &ttl,
                                        &canon));
             if (rc6 != ERANGE || herrno != NETDB_INTERNAL)
              break;
             tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
           }

         if (rc6 != 0 && herrno == NETDB_INTERNAL)
           goto out;

         /* If the IPv6 lookup has been successful do not use the
            buffer used in that lookup, use a new one.  */
         if (status[0] == NSS_STATUS_SUCCESS && rc6 == 0)
           {
             tmpbuf4len = 512;
             tmpbuf4 = alloca (tmpbuf4len);
           }
         else
           {
             tmpbuf4len = tmpbuf6len;
             tmpbuf4 = tmpbuf6;
           }

         /* Next collect IPv4 information.  */
         while (1)
           {
             rc4 = 0;
             status[1] = DL_CALL_FCT (fct, (key, AF_INET, &th[1], tmpbuf4,
                                        tmpbuf4len, &rc4, &herrno,
                                        ttl == INT32_MAX ? &ttl : NULL,
                                        canon == NULL ? &canon : NULL));
             if (rc4 != ERANGE || herrno != NETDB_INTERNAL)
              break;
             tmpbuf4 = extend_alloca (tmpbuf4, tmpbuf4len, 2 * tmpbuf4len);
           }

         if (rc4 != 0 && herrno == NETDB_INTERNAL)
           goto out;

         if (status[0] != NSS_STATUS_SUCCESS
             && status[1] != NSS_STATUS_SUCCESS)
           goto next_nip;

         /* We found the data.  Count the addresses and the size.  */
         for (int j = 0; j < 2; ++j)
           if (status[j] == NSS_STATUS_SUCCESS)
             for (int i = 0; th[j].h_addr_list[i] != NULL; ++i)
              {
                ++naddrs;
                addrslen += th[j].h_length;
              }

         if (canon == NULL)
           {
             /* Determine the canonical name.  */
             nss_getcanonname_r cfct;
             cfct = __nss_lookup_function (nip, "getcanonname_r");
             if (cfct != NULL)
              {
                const size_t max_fqdn_len = 256;
                char *buf = alloca (max_fqdn_len);
                char *s;
                int rc;

                if (DL_CALL_FCT (cfct, (key, buf, max_fqdn_len, &s,
                                     &rc, &herrno))
                    == NSS_STATUS_SUCCESS)
                  canon = s;
                else
                  /* Set to name now to avoid using gethostbyaddr.  */
                  canon = key;
              }
             else
              {
                struct hostent *he = NULL;
                int herrno;
                struct hostent he_mem;
                void *addr;
                size_t addrlen;
                int addrfamily;

                if (status[1] == NSS_STATUS_SUCCESS)
                  {
                    addr = th[1].h_addr_list[0];
                    addrlen = sizeof (struct in_addr);
                    addrfamily = AF_INET;
                  }
                else
                  {
                    addr = th[0].h_addr_list[0];
                    addrlen = sizeof (struct in6_addr);
                    addrfamily = AF_INET6;
                  }

                size_t tmpbuflen = 512;
                char *tmpbuf = alloca (tmpbuflen);
                int rc;
                while (1)
                  {
                    rc = __gethostbyaddr2_r (addr, addrlen, addrfamily,
                                          &he_mem, tmpbuf, tmpbuflen,
                                          &he, &herrno, NULL);
                    if (rc != ERANGE || herrno != NETDB_INTERNAL)
                     break;
                    tmpbuf = extend_alloca (tmpbuf, tmpbuflen,
                                         tmpbuflen * 2);
                  }

                if (rc == 0)
                  {
                    if (he != NULL)
                     canon = he->h_name;
                    else
                     canon = key;
                  }
              }
           }

         canonlen = canon == NULL ? 0 : (strlen (canon) + 1);

         total = sizeof (*dataset) + naddrs + addrslen + canonlen;


         /* Now we can allocate the data structure.  If the TTL of the
            entry is reported as zero do not cache the entry at all.  */
         if (ttl != 0 && he == NULL)
           {
             dataset = (struct dataset *) mempool_alloc (db, total
                                                   + req->key_len,
                                                   IDX_result_data);
             if (dataset == NULL)
              ++db->head->addfailed;
           }

         if (dataset == NULL)
           {
             /* We cannot permanently add the result in the moment.  But
               we can provide the result as is.  Store the data in some
               temporary memory.  */
             dataset = (struct dataset *) alloca (total + req->key_len);

             /* We cannot add this record to the permanent database.  */
             alloca_used = true;
           }

         /* Fill in the address and address families.  */
         char *addrs = dataset->strdata;
         uint8_t *family = (uint8_t *) (addrs + addrslen);

         for (int j = 0; j < 2; ++j)
           if (status[j] == NSS_STATUS_SUCCESS)
             for (int i = 0; th[j].h_addr_list[i] != NULL; ++i)
              {
                addrs = mempcpy (addrs, th[j].h_addr_list[i],
                               th[j].h_length);
                *family++ = th[j].h_addrtype;
              }

         cp = family;
       }

      /* Fill in the rest of the dataset.  */
      dataset->head.allocsize = total + req->key_len;
      dataset->head.recsize = total - offsetof (struct dataset, resp);
      dataset->head.notfound = false;
      dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
      dataset->head.usable = true;

      /* Compute the timeout time.  */
      dataset->head.timeout = time (NULL) + (ttl == INT32_MAX
                                        ? db->postimeout : ttl);

      dataset->resp.version = NSCD_VERSION;
      dataset->resp.found = 1;
      dataset->resp.naddrs = naddrs;
      dataset->resp.addrslen = addrslen;
      dataset->resp.canonlen = canonlen;
      dataset->resp.error = NETDB_SUCCESS;

      if (canon != NULL)
       cp = mempcpy (cp, canon, canonlen);

      key_copy = memcpy (cp, key, req->key_len);

      assert (cp == (char *) dataset + total);

      /* Now we can determine whether on refill we have to create a
        new record or not.  */
      if (he != NULL)
       {
         assert (fd == -1);

         if (total + req->key_len == dh->allocsize
             && total - offsetof (struct dataset, resp) == dh->recsize
             && memcmp (&dataset->resp, dh->data,
                      dh->allocsize - offsetof (struct dataset,
                                             resp)) == 0)
           {
             /* The data has not changed.  We will just bump the
               timeout value.  Note that the new record has been
               allocated on the stack and need not be freed.  */
             dh->timeout = dataset->head.timeout;
             ++dh->nreloads;
           }
         else
           {
             /* We have to create a new record.  Just allocate
               appropriate memory and copy it.  */
             struct dataset *newp
              = (struct dataset *) mempool_alloc (db, total + req->key_len,
                                              IDX_result_data);
             if (__builtin_expect (newp != NULL, 1))
              {
                /* Adjust pointer into the memory block.  */
                key_copy = (char *) newp + (key_copy - (char *) dataset);

                dataset = memcpy (newp, dataset, total + req->key_len);
                alloca_used = false;
              }
             else
              ++db->head->addfailed;

             /* Mark the old record as obsolete.  */
             dh->usable = false;
           }
       }
      else
       {
         /* We write the dataset before inserting it to the database
            since while inserting this thread might block and so
            would unnecessarily let the receiver wait.  */
         assert (fd != -1);

#ifdef HAVE_SENDFILE
         if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
           {
             assert (db->wr_fd != -1);
             assert ((char *) &dataset->resp > (char *) db->data);
             assert ((char *) &dataset->resp - (char *) db->head + total
                    <= (sizeof (struct database_pers_head)
                       + db->head->module * sizeof (ref_t)
                       + db->head->data_size));
             ssize_t written;
             written = sendfileall (fd, db->wr_fd, (char *) &dataset->resp
                                 - (char *) db->head, total);
# ifndef __ASSUME_SENDFILE
             if (written == -1 && errno == ENOSYS)
              goto use_write;
# endif
           }
         else
# ifndef __ASSUME_SENDFILE
         use_write:
# endif
#endif
           writeall (fd, &dataset->resp, total);
       }

      goto out;

next_nip:
      if (nss_next_action (nip, status[1]) == NSS_ACTION_RETURN)
       break;

      if (nip->next == NULL)
       no_more = -1;
      else
       nip = nip->next;
    }

  /* No result found.  Create a negative result record.  */
  if (he != NULL && rc4 == EAGAIN)
    {
      /* If we have an old record available but cannot find one now
        because the service is not available we keep the old record
        and make sure it does not get removed.  */
      if (reload_count != UINT_MAX && dh->nreloads == reload_count)
       /* Do not reset the value if we never not reload the record.  */
       dh->nreloads = reload_count - 1;
    }
  else
    {
      /* We have no data.  This means we send the standard reply for
        this case.  */
      total = sizeof (notfound);

      if (fd != -1)
       TEMP_FAILURE_RETRY (send (fd, &notfound, total, MSG_NOSIGNAL));

      dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len,
                            IDX_result_data);
      /* If we cannot permanently store the result, so be it.  */
      if (dataset != NULL)
       {
         dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
         dataset->head.recsize = total;
         dataset->head.notfound = true;
         dataset->head.nreloads = 0;
         dataset->head.usable = true;

         /* Compute the timeout time.  */
         dataset->head.timeout = time (NULL) + db->negtimeout;

         /* This is the reply.  */
         memcpy (&dataset->resp, &notfound, total);

         /* Copy the key data.  */
         key_copy = memcpy (dataset->strdata, key, req->key_len);
       }
      else
       ++db->head->addfailed;
   }

 out:
  _res.options = old_res_options;

  if (dataset != NULL && !alloca_used)
    {
      /* If necessary, we also propagate the data to disk.  */
      if (db->persistent)
       {
         // XXX async OK?
         uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
         msync ((void *) pval,
               ((uintptr_t) dataset & pagesize_m1) + total + req->key_len,
               MS_ASYNC);
       }

      /* Now get the lock to safely insert the records.  */
      pthread_rwlock_rdlock (&db->lock);

      (void) cache_add (req->type, key_copy, req->key_len, &dataset->head,
                     true, db, uid, he == NULL);

      pthread_rwlock_unlock (&db->lock);

      /* Mark the old entry as obsolete.  */
      if (dh != NULL)
       dh->usable = false;
    }
}

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void readdhstai ( struct database_dyn db,
struct hashentry he,
struct datahead dh 
)

Definition at line 581 of file aicache.c.

{
  request_header req =
    {
      .type = GETAI,
      .key_len = he->len
    };

  addhstaiX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}

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Variable Documentation

Initial value:
{
  .version = NSCD_VERSION,
  .found = 0,
  .naddrs = 0,
  .addrslen = 0,
  .canonlen = 0,
  .error = 0
}

Definition at line 50 of file aicache.c.