Allow to export errors as environment variables

Introduce a new option to export errors in environment variables.
This allows applications to display better errors or take actions based
on the returned error type.

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-by: Robbie Harwood <rharwood@redhat.com>

Resolves #128
Resolves #129

Author: simo5

README

@@ -379,3 +379,22 @@ the default owners and/or mode will be retained.
 
 #### Example
     GssapiDelegCcachePerms mode:0660 gid:webuiworkers
+
+
+### GssapiPublishErrors
+
+This option is used to publish errors as Environment Variables for use by
+httpd processes.
+
+A general error type is provided in the MAG_ERROR variable, and can have the
+following values: "GSS ERROR", "INTERNAL ERROR", "AUTH NOT ALLOWED"
+Additionally, in the variable named MAG_ERROR_TEXT there may be a free form
+error message.
+
+When the error type is "GSS ERROR" the variables GSS_ERROR_MAJ and
+GSS_ERROR_MIN contain the numeric errors returned by GSSAPI, and the
+MAG_ERROR_TEXT will contain a GSS Error message, possibly prepended by
+an additional message that provides more context.
+
+- **Enable with:** GssapiPublishErrors On
+- **Default:** GssapiPublishErrors Off

src/environ.c

@@ -366,3 +366,17 @@ void mag_set_req_data(request_rec *req,
     ap_set_module_config(req->request_config, &auth_gssapi_module, mc->env);
     mag_export_req_env(req, mc->env);
 }
+
+void mag_publish_error(request_rec *req, uint32_t maj, uint32_t min,
+                       const char *gss_err, const char *mag_err)
+{
+    if (gss_err) {
+        apr_table_set(req->subprocess_env, "GSS_ERROR_MAJ",
+                      apr_psprintf(req->pool, "%u", (unsigned)maj));
+        apr_table_set(req->subprocess_env, "GSS_ERROR_MIN",
+                      apr_psprintf(req->pool, "%u", (unsigned)min));
+        apr_table_set(req->subprocess_env, "MAG_ERROR_TEXT", gss_err);
+    }
+    if (mag_err)
+        apr_table_set(req->subprocess_env, "MAG_ERROR", mag_err);
+}

src/environ.h

@@ -13,3 +13,6 @@ void mag_export_req_env(request_rec *req, apr_table_t *env);
 void mag_set_req_data(request_rec *req,
                       struct mag_config *cfg,
                       struct mag_conn *mc);
+
+void mag_publish_error(request_rec *req, uint32_t maj, uint32_t min,
+                       const char *gss_err, const char *mag_err);