LDAP not working with libcurl multi_socket interface

[saurabhsingh-dev]

I did this

In my Ldap multi interface program, Ldap request started failing once i upgraded from curl-7.69.0 to curl-8.4.0.

So i tried latest curl version 8.8.0, where still seeing the same issue.

To rule out my program specific issues, i used standalone program for same from curl examples here multi-uv

compiled:
gcc -g -o multi-uv multi-uv.c -luv -lcurl

Run with licurl complied with debug mode:

root@100-65-8-98:/tmp# ./multi-uv ldap://100.66.51.22:10389/ou=consumers,ou=system
./multi-uv: /opt/avi/lib/libcurl.so.4: no version information available (required by ./multi-uv)
CURL_OPENLDAP_TRACE = 65535
curl version: 8.8.0 OpenSSL/1.1.1f
* !!! WARNING !!!
* This is a debug build of libcurl, do not use in production.
Added download ldap://100.66.51.22:10389/ou=consumers,ou=system -> 1.download
* STATE: INIT => SETUP handle 0x55c66c5999f8; line 1971
* STATE: SETUP => CONNECT handle 0x55c66c5999f8; line 1987
* Added connection 0. The cache now contains 1 members
* STATE: CONNECT => CONNECTING handle 0x55c66c5999f8; line 2023
*   Trying 100.66.51.22:10389...
* Connected to 100.66.51.22 (100.66.51.22) port 10389
* STATE: CONNECTING => PROTOCONNECT handle 0x55c66c5999f8; line 2131
* LDAP 0x55c66c594bf8 state change from STOP to BIND
* STATE: PROTOCONNECT => PROTOCONNECTING handle 0x55c66c5999f8; line 2155
* Operation timed out after 10008 milliseconds with 0 bytes received
* multi_done[PROTOCONNECTING]: status: 28 prem: 1 done: 0
* multi_done, not reusing connection=0, forbid=0, close=1, premature=1, conn_multiplex=0
* The cache now contains 0 members
* Curl_disconnect(conn #0, dead=1)
* Closing connection
ldap://100.66.51.22:10389/ou=consumers,ou=system DONE

Things i added in mentioned standalone program for testing:

curl_easy_setopt(handle, CURLOPT_VERBOSE, 1L); // debug enable
curl_easy_setopt(handle, CURLOPT_TIMEOUT, 10L); // 2 sec
//added before curl_multi_add_handle

g_version = curl_version_info(CURLVERSION_NOW);
fprintf(stderr, "curl version: %s %s\n", g_version->version, g_version->ssl_version);
// added in main and printed

Points from my debugging using gdb:

1. oldap_connecting is been called immediately after oldap_connect, since response is not received yet, ldap_result returns 0, which is timeout.
2. multi_runsingle is not calling oldap_connecting again for response check.
3. looks multi_runsingle -> oldp_connecting should be called when data is available or repeated calls should be made.

I expected the following

Following run with curl 7.69.0, works fine.

root@100-65-8-98:/tmp# ./multi-uv ldap://100.66.51.22:10389/ou=consumers,ou=system
./multi-uv: /opt/avi/lib/libcurl.so.4: no version information available (required by ./multi-uv)
CURL_OPENLDAP_TRACE = 65535
curl version: 7.69.0 OpenSSL/1.1.1f
Added download ldap://100.66.51.22:10389/ou=consumers,ou=system -> 1.download
* STATE: INIT => CONNECT handle 0x564c5f4ca888; line 1617 (connection #-5000)
* Marked for [keep alive]: OpenLDAP default
* Added connection 0. The cache now contains 1 members
*   Trying 100.66.51.22:10389...
* STATE: CONNECT => WAITCONNECT handle 0x564c5f4ca888; line 1673 (connection #0)
* Connected to 100.66.51.22 (100.66.51.22) port 10389 (#0)
* STATE: WAITCONNECT => SENDPROTOCONNECT handle 0x564c5f4ca888; line 1791 (connection #0)
* STATE: SENDPROTOCONNECT => PROTOCONNECT handle 0x564c5f4ca888; line 1808 (connection #0)
* STATE: PROTOCONNECT => DO handle 0x564c5f4ca888; line 1827 (connection #0)
* LDAP local: ldap://100.66.51.22:10389/ou=consumers,ou=system
* STATE: DO => DO_DONE handle 0x564c5f4ca888; line 1882 (connection #0)
* STATE: DO_DONE => PERFORM handle 0x564c5f4ca888; line 2003 (connection #0)
* STATE: PERFORM => DONE handle 0x564c5f4ca888; line 2193 (connection #0)
* multi_done
* Connection #0 to host 100.66.51.22 left intact
* Expire cleared (transfer 0x564c5f4ca888)
ldap://100.66.51.22:10389/ou=consumers,ou=system DONE

curl/libcurl version

root@100-65-8-98:/opt/avi/lib# curl -V
WARNING: this libcurl is Debug-enabled, do not use in production

curl 8.8.0 (x86_64-pc-linux-gnu) libcurl/8.8.0 OpenSSL/1.1.1f zlib/1.2.11 libidn2/2.2.0 nghttp2/1.40.0 OpenLDAP/2.4.49
Release-Date: 2024-05-22
Protocols: dict file ftp ftps gopher gophers http https imap imaps ipfs ipns ldap ldaps mqtt pop3 pop3s rtsp smb smbs smtp smtps telnet tftp
Features: alt-svc AsynchDNS Debug HSTS HTTP2 HTTPS-proxy IDN IPv6 Largefile libz NTLM SSL threadsafe TLS-SRP TrackMemory UnixSockets

operating system

Linux 100-65-8-98 5.4.0-174-generic #193-Ubuntu SMP Thu Mar 7 14:29:28 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

[bagder]

I believe this problem can be reproduced with a debug-build on git master like this:

curl --test-event -v "ldaps://ldap.udel.edu/ou=people,o=udel.edu??sub?(udUsernum=82515)"

[icing]

Fixed for me in #14011.

[saurabhsingh-dev]

Thanks for quick resolution. Verified the fix in my environment. its working for me now.