From 5d6404d780883f404dcfaa7209ab926b0af32c40 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=B8=D0=BB=D1=8F=D0=BD=20=D0=9F=D0=B0=D0=BB=D0=B0?=
 =?UTF-8?q?=D1=83=D0=B7=D0=BE=D0=B2?= <git-dpa@aegee.org>
Date: Mon, 19 Aug 2024 14:46:45 +0300
Subject: [PATCH] xml_add_ns: try a different namespace prefix, if the current
 one is in use

The problem is with XML requests, which utilize in a child node a
namespace with a prefix, which prefix was already added in the XML
response to the root node.
---
 cassandane/tiny-tests/Caldav/calendar_setcolor | 12 ++++++------
 imap/http_dav.c                                | 10 ++++++++--
 2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/cassandane/tiny-tests/Caldav/calendar_setcolor b/cassandane/tiny-tests/Caldav/calendar_setcolor
index 65dda07508..fa3ec2eecc 100644
--- a/cassandane/tiny-tests/Caldav/calendar_setcolor
+++ b/cassandane/tiny-tests/Caldav/calendar_setcolor
@@ -24,11 +24,11 @@ EOF
 
     my $propfindXml = <<EOF;
 <?xml version="1.0" encoding="UTF-8"?>
-<D:propfind xmlns:D="DAV:" xmlns:A="http://apple.com/ns/ical/">
-  <D:prop>
-    <A:calendar-color/>
-  </D:prop>
-</D:propfind>
+<propfind xmlns="DAV:">
+  <prop>
+    <calendar-color xmlns="http://apple.com/ns/ical/"/>
+  </prop>
+</propfind>
 EOF
 
     # Assert that color isn't set.
@@ -42,7 +42,7 @@ EOF
     $response = $CalDAV->Request('PROPPATCH', "/dav/calendars/user/cassandane/". $CalendarId,
                                     $proppatchXml, 'Content-Type' => 'text/xml');
 
-    # Assert color ist set.
+    # Assert color is set.
     $response = $CalDAV->Request('PROPFIND', "/dav/calendars/user/cassandane/". $CalendarId,
                                  $propfindXml, 'Content-Type' => 'text/xml');
     $propstat = $response->{'{DAV:}response'}[0]{'{DAV:}propstat'}[0];
diff --git a/imap/http_dav.c b/imap/http_dav.c
index 9e7625e99b..fa89a35ec9 100644
--- a/imap/http_dav.c
+++ b/imap/http_dav.c
@@ -1340,8 +1340,14 @@ static int xml_add_ns(xmlNodePtr req, xmlNsPtr *respNs, xmlNodePtr root)
                     ensure_ns(respNs, NS_JMAPCAL, root,
                               (const char *) nsDef->href,
                               (const char *) nsDef->prefix);
-                else
-                    xmlNewNs(root, nsDef->href, nsDef->prefix);
+                else if (!xmlNewNs(root, nsDef->href, nsDef->prefix)) {
+                    /* namespace prefix already in use */
+                    char myprefix[20];
+                    snprintf(myprefix, sizeof(myprefix), "X%X", strhash((const char *) nsDef->href) & 0xffff);
+                    xmlFree((char *) nsDef->prefix);
+                    nsDef->prefix = xmlStrdup(BAD_CAST myprefix);
+                    xmlNewNs(root, nsDef->href, BAD_CAST myprefix); // could again return NULL
+		}
             }
         }