resolv: Track single-request fallback via _res._flags (bug 31476)

This avoids changing _res.options, which inteferes with change
detection as part of automatic reloading of /etc/resolv.conf.

Reviewed-by: DJ Delorie <dj@redhat.com>
(cherry picked from commit 868ab8923a)
This commit is contained in:
Florian Weimer 2024-06-13 18:56:30 +02:00
parent 3da1b0064a
commit 708f507e30
3 changed files with 10 additions and 5 deletions

1
NEWS
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@ -64,6 +64,7 @@ The following bugs are resolved with this release:
[31183] Wide stream buffer size reduced MB_LEN_MAX bytes after bug 17522 fix
[31184] FAIL: elf/tst-tlsgap
[31185] Incorrect thread point access in _dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic
[31476] resolv: Track single-request fallback via _res._flags
[31890] resolv: Allow short error responses to match any DNS query
[31965] rseq extension mechanism does not work as intended

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@ -947,9 +947,11 @@ send_dg(res_state statp,
seconds /= statp->nscount;
if (seconds <= 0)
seconds = 1;
bool single_request_reopen = (statp->options & RES_SNGLKUPREOP) != 0;
bool single_request = (((statp->options & RES_SNGLKUP) != 0)
| single_request_reopen);
bool single_request_reopen = ((statp->options & RES_SNGLKUPREOP)
|| (statp->_flags & RES_F_SNGLKUPREOP));
bool single_request = ((statp->options & RES_SNGLKUP)
|| (statp->_flags & RES_F_SNGLKUP)
|| single_request_reopen);
int save_gotsomewhere = *gotsomewhere;
int retval;
@ -1006,14 +1008,14 @@ send_dg(res_state statp,
have received the first answer. */
if (!single_request)
{
statp->options |= RES_SNGLKUP;
statp->_flags |= RES_F_SNGLKUP;
single_request = true;
*gotsomewhere = save_gotsomewhere;
goto retry;
}
else if (!single_request_reopen)
{
statp->options |= RES_SNGLKUPREOP;
statp->_flags |= RES_F_SNGLKUPREOP;
single_request_reopen = true;
*gotsomewhere = save_gotsomewhere;
__res_iclose (statp, false);

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@ -26,6 +26,8 @@
#define RES_F_VC 0x00000001 /* Socket is TCP. */
#define RES_F_CONN 0x00000002 /* Socket is connected. */
#define RES_F_EDNS0ERR 0x00000004 /* EDNS0 caused errors. */
#define RES_F_SNGLKUP 0x00200000 /* Private version of RES_SNGLKUP. */
#define RES_F_SNGLKUPREOP 0x00400000 /* Private version of RES_SNGLKUPREOP. */
/* The structure HEADER is normally aligned on a word boundary. In
some code, we need to access this structure when it may be aligned