Index: openacs-4/packages/acs-automated-testing/tcl/aa-test-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-automated-testing/tcl/aa-test-procs.tcl,v
diff -u -r1.79.2.69 -r1.79.2.70
--- openacs-4/packages/acs-automated-testing/tcl/aa-test-procs.tcl	26 Feb 2024 09:51:59 -0000	1.79.2.69
+++ openacs-4/packages/acs-automated-testing/tcl/aa-test-procs.tcl	5 Jul 2024 13:43:29 -0000	1.79.2.70
@@ -1330,10 +1330,10 @@
         #aa_log "HTTP: user_info [ns_quotehtml <$user_info>]"
         #aa_log "HTTP: start session_info [ns_quotehtml <$session>]"
 
-        set url [acs::test::url]
-        set urlInfo [ns_parseurl $url]
+        set test_url [acs::test::url]
+        set urlInfo [ns_parseurl $test_url]
         set address [dict get $urlInfo host]
-        set url "$url/$request"
+        set url ${test_url}/${request}
 
         #
         # Either authenticate via user_info (when specified) or via
@@ -1404,6 +1404,17 @@
                 if {![string match "3??" $status] || $location eq ""} {
                     break
                 }
+
+                #
+                # According to
+                # https://www.rfc-editor.org/rfc/rfc7231#section-7.1.2,
+                # the location header may return a relative URL as
+                # well.
+                #
+                set location [util::complete_location \
+                                  -location $location \
+                                  -complete_url $test_url]
+
             }
         } finally {
             #
Index: openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl,v
diff -u -r1.30.2.29 -r1.30.2.30
--- openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl	25 Feb 2024 16:13:42 -0000	1.30.2.29
+++ openacs-4/packages/acs-tcl/tcl/http-client-procs.tcl	5 Jul 2024 13:43:26 -0000	1.30.2.30
@@ -1128,6 +1128,15 @@
         set location ${location}?${urlvars}
     }
 
+    #
+    # According to
+    # https://www.rfc-editor.org/rfc/rfc7231#section-7.1.2, the
+    # location header may return a relative URL as well.
+    #
+    set location [util::complete_location \
+                      -location $location \
+                      -complete_url $url]
+
     if {$method eq "GET"} {
         return [$this_proc \
                     -method          GET \
@@ -1494,7 +1503,6 @@
     set r_headers [ns_set array $resp_headers]
     ns_set free $resp_headers
 
-
     # Redirection handling
     if {$depth < $max_depth} {
         incr depth
Index: openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl,v
diff -u -r1.189.2.175 -r1.189.2.176
--- openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl	3 Jun 2024 17:47:19 -0000	1.189.2.175
+++ openacs-4/packages/acs-tcl/tcl/utilities-procs.tcl	5 Jul 2024 13:43:29 -0000	1.189.2.176
@@ -1964,6 +1964,51 @@
     return $result
 }
 
+ad_proc util::complete_location {
+    -location:required
+    -complete_url
+} {
+    Completes specified relative URL. When no complete URL is
+    specified for reference, it will assume the current host as the
+    server.
+
+    The purpose of this utility is to be used by HTTP clients to
+    complete URLs coming from the Location response header in case of
+    a redirect, which according to RFC 7231 may also be relative.
+
+    @param location a supposedly relative URL to complete. When the
+                    URL is already complete, it will be returned
+                    as-is.
+    @param complete_url URL of the redirected request. A complete URL
+                        from which we want to read the host. When
+                        missing, the URL will be completed using the
+                        result of util_current_location.
+
+    @return a complete absolute URL
+
+    @see https://www.rfc-editor.org/rfc/rfc7231#section-7.1.2
+} {
+    if {![info exists complete_url]} {
+        set complete_url [util_current_location]
+    } elseif {![dict exists [ns_parseurl -strict $complete_url] host]} {
+        error "util::complete_location: '$complete_url' is not a valid complete URL"
+    }
+
+    set parsed_location [ns_parseurl -strict $location]
+    if {[dict exists $parsed_location host]} {
+        return $location
+    }
+
+    util::split_location $complete_url proto hostname port
+
+    set host_url [util::join_location \
+                      -proto $proto \
+                      -hostname $hostname \
+                      -port $port]
+
+    return [ns_absoluteurl $location $host_url]
+}
+
 ad_proc -public util::configured_location {{-suppress_port:boolean}} {
 
     Return the configured location as configured for the current
Index: openacs-4/packages/acs-tcl/tcl/test/utilities-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/test/Attic/utilities-procs.tcl,v
diff -u -r1.1.2.20 -r1.1.2.21
--- openacs-4/packages/acs-tcl/tcl/test/utilities-procs.tcl	21 Apr 2023 16:15:46 -0000	1.1.2.20
+++ openacs-4/packages/acs-tcl/tcl/test/utilities-procs.tcl	5 Jul 2024 13:43:29 -0000	1.1.2.21
@@ -440,6 +440,106 @@
     api
     production_safe
 } -procs {
+    util::complete_location
+} util__complete_url {
+    Test util::complete_location
+} {
+    aa_equals "Basic case" \
+        [string trimright [util::complete_location -location ""] /] \
+        [util_current_location]
+
+    aa_equals "Complete with current location" \
+        [string trimright [util::complete_location -location "/a/b/c"] /] \
+        [util_current_location]/a/b/c \
+
+    aa_equals "Complete an already complete location (normie case)" \
+        [util::complete_location -location "https://example.com/a/b/c"] \
+        "https://example.com/a/b/c" \
+
+    aa_equals "Complete an already complete location (protocol relative)" \
+        [util::complete_location -location "//a/b/c"] \
+        //a/b/c \
+
+    aa_true "Complete an invalid location (relative) - Should fail" \
+        [catch {
+            util::complete_location -location "/file\[/\].html"
+        }]
+
+    aa_true "Complete an invalid location (absolute) - Should fail" \
+        [catch {
+            util::complete_location -location "http://example.com/file\[/\].html"
+        }]
+
+    aa_equals "Basic case with external location" \
+        [string trimright [util::complete_location \
+                               -complete_url "http://example.com" \
+                               -location ""] /] \
+        http://example.com
+
+    aa_equals "Basic case with external location (complete_url has a path)" \
+        [string trimright [util::complete_location \
+                               -complete_url "http://example.com/a/b/c" \
+                               -location ""] /] \
+        http://example.com
+
+    aa_equals "Complete with external location (complete_url just the host)" \
+        [string trimright [util::complete_location \
+                               -complete_url "http://example.com" \
+                               -location "/a/b/c"] /] \
+        http://example.com/a/b/c \
+
+    aa_equals "Complete with external location (complete_url with a path)" \
+        [string trimright [util::complete_location \
+                               -complete_url "http://example.com/d/e/f" \
+                               -location "/a/b/c"] /] \
+        http://example.com/a/b/c \
+
+    aa_equals "Complete an already complete location (normie case)" \
+        [util::complete_location \
+             -complete_url "http://anotherexample.com/d/e/f" \
+             -location "https://example.com/a/b/c"] \
+        "https://example.com/a/b/c" \
+
+    aa_equals "Complete an already complete location (protocol relative)" \
+        [util::complete_location \
+             -complete_url "http://anotherexample.com/d/e/f" \
+             -location "//a/b/c"] \
+        //a/b/c \
+
+    aa_true "Complete an invalid location (relative) - Should fail" \
+        [catch {
+            util::complete_location \
+                -complete_url "http://example.com/d/e/f" \
+                -location "/file\[/\].html"
+        }]
+
+    aa_true "Complete an invalid location (absolute) - Should fail" \
+        [catch {
+            util::complete_location \
+                -complete_url "http://example.com/d/e/f" \
+                -location "http://example.com/file\[/\].html"
+        }]
+
+    aa_true "Complete with an invalid complete_url - Should fail" \
+        [catch {
+            util::complete_location \
+                -complete_url "http://example.com/file\[/\].html" \
+                -location "/file/a/b"
+        }]
+
+    aa_true "Complete with a relative complete_url - Should fail" \
+        [catch {
+            util::complete_location \
+                -complete_url "/c/d/e" \
+                -location "/file/a/b"
+        }]
+}
+
+
+aa_register_case -cats {
+    api
+    production_safe
+} -procs {
     util::file_content_check
 } util__file_content_check {
     Test util::file_content_check.