[libmicrohttpd] 02/09: digestauth: when checking 'nc' reuse always check nonce match first

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karlson2k pushed a commit to branch master
in repository libmicrohttpd.

commit d6db60e373525134d4a71e8796c5748bf497829a
Author: Evgeny Grin (Karlson2k) <k2k@narod.ru>
AuthorDate: Sun May 1 15:04:45 2022 +0300

    digestauth: when checking 'nc' reuse always check nonce match first
    
    While the validity of nonce itself was already checked, it could be stale
    nonce, so let's make sure that re-use of 'nc' is limited to the same
    nonce only.
---
 src/microhttpd/digestauth.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/microhttpd/digestauth.c b/src/microhttpd/digestauth.c
index 943f1eb5..ff13cf09 100644
--- a/src/microhttpd/digestauth.c
+++ b/src/microhttpd/digestauth.c
@@ -559,7 +559,8 @@ add_nonce (struct MHD_Connection *connection,
   MHD_mutex_lock_chk_ (&daemon->nnc_lock);
   memcpy (nn->nonce,
           nonce,
-          noncelen + 1);
+          noncelen);
+  nn->nonce[noncelen] = 0;
   nn->nc = 0;
   nn->nmask = 0;
   MHD_mutex_unlock_chk_ (&daemon->nnc_lock);
@@ -612,20 +613,25 @@ check_nonce_nc (struct MHD_Connection *connection,
 
   MHD_mutex_lock_chk_ (&daemon->nnc_lock);
 
+  if ( (0 != memcmp (nn->nonce, nonce, noncelen)) ||
+       (0 != nn->nonce[noncelen]) )
+  {
+    /* Nonce does not match, fail */
+    stale = true;
+    ret = MHD_NO;
+  }
   /* Note that we use 64 here, as we do not store the
      bit for 'nn->nc' itself in 'nn->nmask' */
-  if ( (nc < nn->nc) &&
-       (nc + 64 > nc /* checking for overflow */) &&
-       (nc + 64 >= nn->nc) &&
-       (0 == ((1LLU << (nn->nc - nc - 1)) & nn->nmask)) )
+  else if ( (nc < nn->nc) &&
+            (nc + 64 > nc /* checking for overflow */) &&
+            (nc + 64 >= nn->nc) &&
+            (0 == ((1LLU << (nn->nc - nc - 1)) & nn->nmask)) )
   {
     /* Out-of-order nonce, but within 64-bit bitmask, set bit */
     nn->nmask |= (1LLU << (nn->nc - nc - 1));
     ret = MHD_YES;
   }
-  else if ( (nc <= nn->nc) ||
-            (0 != strcmp (nn->nonce,
-                          nonce)) )
+  else if (nc <= nn->nc)
   {
     /* Nonce does not match, fail */
     stale = true;

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