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 868ab8923a2ec977faafec97ecafac0c3159c1b2)

diff --git a/NEWS b/NEWS
index 3f124cbada3e3a9f582e37757d8e51cb0bce0c61..68f10fdfc73408769c644fc3ad3d605ca8cd6e26 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -98,6 +98,7 @@ The following bugs are resolved with this release:
   [30843] potential use-after-free in getcanonname (CVE-2023-4806)
   [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
 \f

diff --git a/resolv/res_send.c b/resolv/res_send.c
index aab885f7565cb1df1cfe8f9ff500774d18f8a850..1bcc98ed21d5a9ece7a9477a6a20aff253eeb97b 100644 (file)
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -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);

diff --git a/resolv/resolv-internal.h b/resolv/resolv-internal.h
index bb12f474d266e451404ab550d8de733bd5992e34..170a4b9101b721dcbbcc21805e081ba32a0f2012 100644 (file)
--- a/resolv/resolv-internal.h
+++ b/resolv/resolv-internal.h
@@ -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