https://bugs.openldap.org/show_bug.cgi?id=10205

Issue ID: 10205 Summary: SSL handshake blocks forever in async mode if server unaccessible Product: OpenLDAP Version: 2.5.17 Hardware: x86_64 OS: Linux Status: UNCONFIRMED Keywords: needs_review Severity: normal Priority: --- Component: libraries Assignee: bugs@openldap.org Reporter: regtube@hotmail.com Target Milestone: ---

When ldaps:// scheme is used to connect to currently unaccessible server with LDAP_OPT_CONNECT_ASYNC and LDAP_OPT_NETWORK_TIMEOUT options set, it blocks forever on SSL_connect.

Here is a trace: ldap_sasl_bind ldap_send_initial_request ldap_new_connection 1 1 0 ldap_int_open_connection ldap_connect_to_host: TCP winserv.test.net:636 ldap_new_socket: 3 ldap_prepare_socket: 3 ldap_connect_to_host: Trying 192.168.56.2:636 ldap_pvt_connect: fd: 3 tm: 30 async: -1 ldap_ndelay_on: 3 attempting to connect: connect errno: 115 ldap_int_poll: fd: 3 tm: 0 ldap_err2string [2024-04-25 15:41:27.112] [error] [:1] bind(): Connecting (X) [2024-04-25 15:41:27.112] [error] [:1] err: -18 ldap_sasl_bind ldap_send_initial_request ldap_int_poll: fd: 3 tm: 0 ldap_is_sock_ready: 3 ldap_ndelay_off: 3 TLS trace: SSL_connect:before SSL initialization TLS trace: SSL_connect:SSLv3/TLS write client hello

Looks like it happens because non-blocking mode is cleared from the socket (ldap_ndelay_off) after the first poll for write, and non-blocking mode is never restored before attempt to do tls connect, because of the check that assumes that non-blocking mode has already been set for async mode: if ( !async ) { /* if async, this has already been set */ ber_sockbuf_ctrl( sb, LBER_SB_OPT_SET_NONBLOCK, (void*)1 ); } while in fact it was cleared.