bug#64089: Acknowledgement (30.0.50; `ldap-search' errors out with `wrong-type-argument listp' when called WITHDN == t)

[Jens Schmidt via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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With the following patch things work as expected:

(ldap-search "(uid=<uid>)"
               "ldap://<host>"
               '("mail")
               nil
               t)
=> ((("dn" "cn=<NAME>,L=<REGION>,DC=<DOMAIN>,DC=COM") ("mail" 
"<name>@<domain>.com")))

I tried to make the patch as conservative as possible and intentionally 
do not check syntax of the dn line if its parsing is not required.


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From a646f5aa23f051f19910286c1bf9f4580a858f0f Mon Sep 17 00:00:00 2001
From: Jens Schmidt <jschmidt4gnu@vodafonemail.de>
Date: Fri, 16 Jun 2023 00:04:04 +0200
Subject: [PATCH] Fix parsing of dn line if WITHDN is non-nil

Function `ldap-search' errors out with `wrong-type-argument listp'
when called with WITHDN non-nil.
* lisp/net/ldap.el (ldap-search-internal): Parse the dn line
correctly so that `ldap-search' can grok it.  (Bug#64089)
---
 lisp/net/ldap.el | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lisp/net/ldap.el b/lisp/net/ldap.el
index 78405414a28..4275b45e6f5 100644
--- a/lisp/net/ldap.el
+++ b/lisp/net/ldap.el
@@ -703,7 +703,17 @@ ldap-search-internal
 	(while (progn
 		 (skip-chars-forward " \t\n")
 		 (not (eobp)))
-          (setq dn (buffer-substring (point) (line-end-position)))
+          ;; Ignore first (dn) line if WITHDN equals nil.  If WITHDN
+          ;; is non-nil, check syntax of the line and split it into a
+          ;; pair as expected by `ldap-decode-attribute' (Bug#64089).
+          ;; If the syntax is wrong, better throw an error here, since
+          ;; otherwise `ldap-decode-attribute' would throw a much less
+          ;; comprehensible error later.
+          (cond ((not withdn))
+                ((looking-at "^dn[=:\t ]+\\(.*\\)$")
+                 (setq dn (list "dn" (match-string 1))))
+                (t (error "Incorrect dn line \"%s\" in ldapsearch result"
+                          (buffer-substring (point) (line-end-position)))))
 	  (forward-line 1)
           (while (looking-at "^\\([A-Za-z][-A-Za-z0-9]*\
 \\|[0-9]+\\(?:\\.[0-9]+\\)*\\)\\(;[-A-Za-z0-9]+\\)*[=:\t ]+\
-- 
2.30.2