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https://sourceware.org/git/glibc.git
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nss_files: Refactor gethostbyname3 multi case into separate function
This is in preparation of further cleanup work.
This commit is contained in:
Florian Weimer
parent
a8dce6197a
commit
8ed70de2fa
@ -1,3 +1,9 @@
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2017-10-10 Florian Weimer <fweimer@redhat.com>
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* nss/nss_files/files-hosts.c (gethostbyname3_multi): New
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function.
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(_nss_files_gethostbyname3_r): Call it.
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2017-10-09 Joseph Myers <joseph@codesourcery.com>
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* sysdeps/generic/math-type-macros.h [!declare_mgen_alias]: Give
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@ -115,6 +115,206 @@ DB_LOOKUP (hostbyaddr, ,,,
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}, const void *addr, socklen_t len, int af)
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#undef EXTRA_ARGS_VALUE
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static enum nss_status
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gethostbyname3_multi (FILE * stream, const char *name, int af,
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struct hostent *result, char *buffer, size_t buflen,
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int *errnop, int *herrnop, int flags)
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{
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/* We have to get all host entries from the file. */
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size_t tmp_buflen = MIN (buflen, 4096);
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char tmp_buffer_stack[tmp_buflen]
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__attribute__ ((__aligned__ (__alignof__ (struct hostent_data))));
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char *tmp_buffer = tmp_buffer_stack;
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struct hostent tmp_result_buf;
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int naddrs = 1;
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int naliases = 0;
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char *bufferend;
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bool tmp_buffer_malloced = false;
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enum nss_status status;
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while (result->h_aliases[naliases] != NULL)
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++naliases;
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bufferend = (char *) &result->h_aliases[naliases + 1];
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again:
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while ((status = internal_getent (stream, &tmp_result_buf, tmp_buffer,
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tmp_buflen, errnop, herrnop, af,
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flags))
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== NSS_STATUS_SUCCESS)
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{
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int matches = 1;
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struct hostent *old_result = result;
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result = &tmp_result_buf;
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/* The following piece is a bit clumsy but we want to use the
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`LOOKUP_NAME_CASE' value. The optimizer should do its
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job. */
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do
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{
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LOOKUP_NAME_CASE (h_name, h_aliases)
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result = old_result;
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}
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while ((matches = 0));
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if (matches)
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{
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/* We could be very clever and try to recycle a few bytes
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in the buffer instead of generating new arrays. But
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we are not doing this here since it's more work than
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it's worth. Simply let the user provide a bit bigger
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buffer. */
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char **new_h_addr_list;
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char **new_h_aliases;
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int newaliases = 0;
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size_t newstrlen = 0;
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int cnt;
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/* Count the new aliases and the length of the strings. */
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while (tmp_result_buf.h_aliases[newaliases] != NULL)
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{
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char *cp = tmp_result_buf.h_aliases[newaliases];
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++newaliases;
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newstrlen += strlen (cp) + 1;
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}
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/* If the real name is different add it also to the
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aliases. This means that there is a duplication
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in the alias list but this is really the user's
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problem. */
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if (strcmp (old_result->h_name,
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tmp_result_buf.h_name) != 0)
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{
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++newaliases;
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newstrlen += strlen (tmp_result_buf.h_name) + 1;
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}
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/* Make sure bufferend is aligned. */
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assert ((bufferend - (char *) 0) % sizeof (char *) == 0);
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/* Now we can check whether the buffer is large enough.
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16 is the maximal size of the IP address. */
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if (bufferend + 16 + (naddrs + 2) * sizeof (char *)
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+ roundup (newstrlen, sizeof (char *))
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+ (naliases + newaliases + 1) * sizeof (char *)
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>= buffer + buflen)
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{
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*errnop = ERANGE;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_TRYAGAIN;
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goto out;
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}
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new_h_addr_list =
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(char **) (bufferend
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+ roundup (newstrlen, sizeof (char *))
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+ 16);
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new_h_aliases =
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(char **) ((char *) new_h_addr_list
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+ (naddrs + 2) * sizeof (char *));
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/* Copy the old data in the new arrays. */
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for (cnt = 0; cnt < naddrs; ++cnt)
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new_h_addr_list[cnt] = old_result->h_addr_list[cnt];
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for (cnt = 0; cnt < naliases; ++cnt)
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new_h_aliases[cnt] = old_result->h_aliases[cnt];
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/* Store the new strings. */
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cnt = 0;
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while (tmp_result_buf.h_aliases[cnt] != NULL)
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{
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new_h_aliases[naliases++] = bufferend;
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bufferend = (__stpcpy (bufferend,
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tmp_result_buf.h_aliases[cnt])
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+ 1);
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++cnt;
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}
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if (cnt < newaliases)
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{
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new_h_aliases[naliases++] = bufferend;
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bufferend = __stpcpy (bufferend,
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tmp_result_buf.h_name) + 1;
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}
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/* Final NULL pointer. */
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new_h_aliases[naliases] = NULL;
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/* Round up the buffer end address. */
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bufferend += (sizeof (char *)
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- ((bufferend - (char *) 0)
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% sizeof (char *))) % sizeof (char *);
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/* Now the new address. */
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new_h_addr_list[naddrs++] =
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memcpy (bufferend, tmp_result_buf.h_addr,
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tmp_result_buf.h_length);
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/* Also here a final NULL pointer. */
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new_h_addr_list[naddrs] = NULL;
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/* Store the new array pointers. */
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old_result->h_aliases = new_h_aliases;
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old_result->h_addr_list = new_h_addr_list;
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/* Compute the new buffer end. */
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bufferend = (char *) &new_h_aliases[naliases + 1];
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assert (bufferend <= buffer + buflen);
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result = old_result;
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}
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}
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if (status == NSS_STATUS_TRYAGAIN)
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{
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size_t newsize = 2 * tmp_buflen;
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if (tmp_buffer_malloced)
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{
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char *newp = realloc (tmp_buffer, newsize);
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if (newp != NULL)
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{
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assert ((((uintptr_t) newp)
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& (__alignof__ (struct hostent_data) - 1))
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== 0);
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tmp_buffer = newp;
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tmp_buflen = newsize;
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goto again;
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}
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}
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else if (!__libc_use_alloca (buflen + newsize))
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{
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tmp_buffer = malloc (newsize);
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if (tmp_buffer != NULL)
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{
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assert ((((uintptr_t) tmp_buffer)
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& (__alignof__ (struct hostent_data) - 1))
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== 0);
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tmp_buffer_malloced = true;
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tmp_buflen = newsize;
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goto again;
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}
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}
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else
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{
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tmp_buffer
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= extend_alloca (tmp_buffer, tmp_buflen,
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newsize
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+ __alignof__ (struct hostent_data));
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tmp_buffer = (char *) (((uintptr_t) tmp_buffer
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+ __alignof__ (struct hostent_data)
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- 1)
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& ~(__alignof__ (struct hostent_data)
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- 1));
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goto again;
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}
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}
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else
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status = NSS_STATUS_SUCCESS;
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out:
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if (tmp_buffer_malloced)
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free (tmp_buffer);
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return status;
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}
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enum nss_status
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_nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
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char *buffer, size_t buflen, int *errnop,
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@ -143,199 +343,8 @@ _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
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if (status == NSS_STATUS_SUCCESS
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&& _res_hconf.flags & HCONF_FLAG_MULTI)
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{
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/* We have to get all host entries from the file. */
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size_t tmp_buflen = MIN (buflen, 4096);
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char tmp_buffer_stack[tmp_buflen]
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__attribute__ ((__aligned__ (__alignof__ (struct hostent_data))));
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char *tmp_buffer = tmp_buffer_stack;
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struct hostent tmp_result_buf;
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int naddrs = 1;
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int naliases = 0;
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char *bufferend;
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bool tmp_buffer_malloced = false;
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while (result->h_aliases[naliases] != NULL)
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++naliases;
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bufferend = (char *) &result->h_aliases[naliases + 1];
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again:
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while ((status = internal_getent (stream, &tmp_result_buf, tmp_buffer,
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tmp_buflen, errnop, herrnop, af,
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flags))
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== NSS_STATUS_SUCCESS)
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{
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int matches = 1;
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struct hostent *old_result = result;
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result = &tmp_result_buf;
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/* The following piece is a bit clumsy but we want to use the
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`LOOKUP_NAME_CASE' value. The optimizer should do its
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job. */
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do
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{
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LOOKUP_NAME_CASE (h_name, h_aliases)
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result = old_result;
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}
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while ((matches = 0));
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if (matches)
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{
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/* We could be very clever and try to recycle a few bytes
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in the buffer instead of generating new arrays. But
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we are not doing this here since it's more work than
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it's worth. Simply let the user provide a bit bigger
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buffer. */
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char **new_h_addr_list;
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char **new_h_aliases;
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int newaliases = 0;
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size_t newstrlen = 0;
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int cnt;
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/* Count the new aliases and the length of the strings. */
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while (tmp_result_buf.h_aliases[newaliases] != NULL)
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{
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char *cp = tmp_result_buf.h_aliases[newaliases];
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++newaliases;
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newstrlen += strlen (cp) + 1;
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}
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/* If the real name is different add it also to the
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aliases. This means that there is a duplication
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in the alias list but this is really the user's
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problem. */
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if (strcmp (old_result->h_name,
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tmp_result_buf.h_name) != 0)
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{
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++newaliases;
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newstrlen += strlen (tmp_result_buf.h_name) + 1;
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}
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/* Make sure bufferend is aligned. */
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assert ((bufferend - (char *) 0) % sizeof (char *) == 0);
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/* Now we can check whether the buffer is large enough.
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16 is the maximal size of the IP address. */
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if (bufferend + 16 + (naddrs + 2) * sizeof (char *)
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+ roundup (newstrlen, sizeof (char *))
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+ (naliases + newaliases + 1) * sizeof (char *)
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>= buffer + buflen)
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{
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*errnop = ERANGE;
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*herrnop = NETDB_INTERNAL;
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status = NSS_STATUS_TRYAGAIN;
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goto out;
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}
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new_h_addr_list =
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(char **) (bufferend
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+ roundup (newstrlen, sizeof (char *))
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+ 16);
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new_h_aliases =
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(char **) ((char *) new_h_addr_list
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+ (naddrs + 2) * sizeof (char *));
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/* Copy the old data in the new arrays. */
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for (cnt = 0; cnt < naddrs; ++cnt)
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new_h_addr_list[cnt] = old_result->h_addr_list[cnt];
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for (cnt = 0; cnt < naliases; ++cnt)
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new_h_aliases[cnt] = old_result->h_aliases[cnt];
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/* Store the new strings. */
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cnt = 0;
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while (tmp_result_buf.h_aliases[cnt] != NULL)
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{
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new_h_aliases[naliases++] = bufferend;
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bufferend = (__stpcpy (bufferend,
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tmp_result_buf.h_aliases[cnt])
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+ 1);
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++cnt;
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}
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if (cnt < newaliases)
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{
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new_h_aliases[naliases++] = bufferend;
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bufferend = __stpcpy (bufferend,
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tmp_result_buf.h_name) + 1;
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}
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/* Final NULL pointer. */
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new_h_aliases[naliases] = NULL;
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/* Round up the buffer end address. */
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bufferend += (sizeof (char *)
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- ((bufferend - (char *) 0)
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% sizeof (char *))) % sizeof (char *);
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/* Now the new address. */
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new_h_addr_list[naddrs++] =
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memcpy (bufferend, tmp_result_buf.h_addr,
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tmp_result_buf.h_length);
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/* Also here a final NULL pointer. */
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new_h_addr_list[naddrs] = NULL;
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/* Store the new array pointers. */
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old_result->h_aliases = new_h_aliases;
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old_result->h_addr_list = new_h_addr_list;
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/* Compute the new buffer end. */
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bufferend = (char *) &new_h_aliases[naliases + 1];
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assert (bufferend <= buffer + buflen);
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result = old_result;
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}
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}
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if (status == NSS_STATUS_TRYAGAIN)
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{
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size_t newsize = 2 * tmp_buflen;
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if (tmp_buffer_malloced)
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{
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char *newp = realloc (tmp_buffer, newsize);
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if (newp != NULL)
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{
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assert ((((uintptr_t) newp)
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& (__alignof__ (struct hostent_data) - 1))
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== 0);
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tmp_buffer = newp;
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tmp_buflen = newsize;
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goto again;
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}
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}
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else if (!__libc_use_alloca (buflen + newsize))
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{
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tmp_buffer = malloc (newsize);
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if (tmp_buffer != NULL)
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{
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assert ((((uintptr_t) tmp_buffer)
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& (__alignof__ (struct hostent_data) - 1))
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== 0);
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tmp_buffer_malloced = true;
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tmp_buflen = newsize;
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goto again;
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}
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}
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else
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{
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tmp_buffer
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= extend_alloca (tmp_buffer, tmp_buflen,
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newsize
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+ __alignof__ (struct hostent_data));
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tmp_buffer = (char *) (((uintptr_t) tmp_buffer
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+ __alignof__ (struct hostent_data)
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- 1)
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& ~(__alignof__ (struct hostent_data)
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- 1));
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goto again;
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}
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}
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else
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status = NSS_STATUS_SUCCESS;
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out:
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if (tmp_buffer_malloced)
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free (tmp_buffer);
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}
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status = gethostbyname3_multi
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(stream, name, af, result, buffer, buflen, errnop, herrnop, flags);
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internal_endent (&stream);
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}
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