dirmngr: Stricter handling of http error codes.

* dirmngr/ks-action.c (ks_action_search): Only retry if the keyserver
responded with a '404 Not Found'.
* dirmngr/ks-engine-hkp.c (send_request): Return http status code.
(ks_hkp_search): Likewise.
(ks_hkp_{get,put}): Adapt call to 'send_request'.
* dirmngr/ks-engine.h (ks_hkp_search): Update prototype.

Signed-off-by: Justus Winter <justus@g10code.com>

dirmngr/ks-action.c

@@ -156,13 +156,13 @@ ks_action_search (ctrl_t ctrl, uri_item_t keyservers,
      parallel and merge them.  We also need to decide what to do with
      errors - it might not be the best idea to ignore an error from
      one server and silently continue with another server.  For now we
-     stop at the first error, unless it is GPG_ERR_NO_DATA, in which
+     stop at the first error, unless the server responds with '404 Not
-     case we try the next server.  Unfortunately, 'send_requests'
+     Found', in which case we try the next server.  */
-     broadly maps all kinds of http errors to GPG_ERR_NO_DATA.  */
   for (uri = keyservers; !err && uri; uri = uri->next)
     {
       int is_http = uri->parsed_uri->is_http;
       int is_ldap = 0;
+      unsigned int http_status;
 #if USE_LDAP
       is_ldap = (strcmp (uri->parsed_uri->scheme, "ldap") == 0
 		 || strcmp (uri->parsed_uri->scheme, "ldaps") == 0
@@ -177,10 +177,12 @@ ks_action_search (ctrl_t ctrl, uri_item_t keyservers,
 	  else
 #endif
 	    {
-	      err = ks_hkp_search (ctrl, uri->parsed_uri, patterns->d, &infp);
+	      err = ks_hkp_search (ctrl, uri->parsed_uri, patterns->d,
+                                   &infp, &http_status);
 	    }
 
-          if (err == gpg_error (GPG_ERR_NO_DATA))
+          if (err == gpg_error (GPG_ERR_NO_DATA)
+              && http_status == 404 /* not found */)
             {
               /* No record found.  Clear error and try next server.  */
               err = 0;

dirmngr/ks-engine-hkp.c

@@ -974,12 +974,13 @@ ks_hkp_housekeeping (time_t curtime)
    R_FP.  HOSTPORTSTR is only used for diagnostics.  If HTTPHOST is
    not NULL it will be used as HTTP "Host" header.  If POST_CB is not
    NULL a post request is used and that callback is called to allow
-   writing the post data.  */
+   writing the post data.  If R_HTTP_STATUS is not NULL, the http
+   status code will be stored there.  */
 static gpg_error_t
 send_request (ctrl_t ctrl, const char *request, const char *hostportstr,
               const char *httphost, unsigned int httpflags,
               gpg_error_t (*post_cb)(void *, http_t), void *post_cb_value,
-              estream_t *r_fp)
+              estream_t *r_fp, unsigned int *r_http_status)
 {
   gpg_error_t err;
   http_session_t session = NULL;
@@ -1050,6 +1051,9 @@ send_request (ctrl_t ctrl, const char *request, const char *hostportstr,
       httpflags |= HTTP_FLAG_FORCE_TLS;
     }
 
+  if (r_http_status)
+    *r_http_status = http_get_status_code (http);
+
   switch (http_get_status_code (http))
     {
     case 200:
@@ -1158,10 +1162,12 @@ handle_send_request_error (gpg_error_t err, const char *request,
 
 
 /* Search the keyserver identified by URI for keys matching PATTERN.
-   On success R_FP has an open stream to read the data.  */
+   On success R_FP has an open stream to read the data.  If
+   R_HTTP_STATUS is not NULL, the http status code will be stored
+   there.  */
 gpg_error_t
 ks_hkp_search (ctrl_t ctrl, parsed_uri_t uri, const char *pattern,
-               estream_t *r_fp)
+               estream_t *r_fp, unsigned int *r_http_status)
 {
   gpg_error_t err;
   KEYDB_SEARCH_DESC desc;
@@ -1248,7 +1254,7 @@ ks_hkp_search (ctrl_t ctrl, parsed_uri_t uri, const char *pattern,
 
   /* Send the request.  */
   err = send_request (ctrl, request, hostport, httphost, httpflags,
-                      NULL, NULL, &fp);
+                      NULL, NULL, &fp, r_http_status);
   if (handle_send_request_error (err, request, &tries))
     {
       reselect = 1;
@@ -1381,7 +1387,7 @@ ks_hkp_get (ctrl_t ctrl, parsed_uri_t uri, const char *keyspec, estream_t *r_fp)
 
   /* Send the request.  */
   err = send_request (ctrl, request, hostport, httphost, httpflags,
-                      NULL, NULL, &fp);
+                      NULL, NULL, &fp, NULL);
   if (handle_send_request_error (err, request, &tries))
     {
       reselect = 1;
@@ -1489,7 +1495,7 @@ ks_hkp_put (ctrl_t ctrl, parsed_uri_t uri, const void *data, size_t datalen)
 
   /* Send the request.  */
   err = send_request (ctrl, request, hostport, httphost, 0,
-                      put_post_cb, &parm, &fp);
+                      put_post_cb, &parm, &fp, NULL);
   if (handle_send_request_error (err, request, &tries))
     {
       reselect = 1;

dirmngr/ks-engine.h

@@ -34,7 +34,7 @@ gpg_error_t ks_hkp_mark_host (ctrl_t ctrl, const char *name, int alive);
 gpg_error_t ks_hkp_print_hosttable (ctrl_t ctrl);
 gpg_error_t ks_hkp_help (ctrl_t ctrl, parsed_uri_t uri);
 gpg_error_t ks_hkp_search (ctrl_t ctrl, parsed_uri_t uri, const char *pattern,
-                           estream_t *r_fp);
+                           estream_t *r_fp, unsigned int *r_http_status);
 gpg_error_t ks_hkp_get (ctrl_t ctrl, parsed_uri_t uri,
                         const char *keyspec, estream_t *r_fp);
 gpg_error_t ks_hkp_put (ctrl_t ctrl, parsed_uri_t uri,