openldap-bugs September 2025

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[Issue 10387] New: Reverse lookup does not work for IPv6 addresses proxied over IPv4
by openldap-its＠openldap.org 01 Sep '25

01 Sep '25

https://bugs.openldap.org/show_bug.cgi?id=10387 Issue ID: 10387 Summary: Reverse lookup does not work for IPv6 addresses proxied over IPv4 Product: OpenLDAP Version: 2.6.10 Hardware: All OS: All Status: UNCONFIRMED Keywords: needs_review Severity: normal Priority: --- Component: slapd Assignee: bugs(a)openldap.org Reporter: +openldap(a)Eero.xn--Hkkinen-5wa.fi Target Milestone: --- I have an IPv4/IPv6 reverse proxy server which listens for ldap[s]:// connections and forwards them using the proxy procotol to an IPv4-only slapd server which listens for pldap[s]:// connections. The slapd server has the global olcReverseLookup setting set to TRUE. The reverse lookup works as expected if an LDAP client connects to the reverse proxy using IPv4. However, if the LDAP client connects to the reverse proxy using IPv6, the reverse lookup does not work. The slap_listener function in the servers/slapd/daemon.c file accepts a connection (https://git.openldap.org/openldap/openldap/-/blob/OPENLDAP_REL_ENG_2_6_10/s…). Because the reverse proxy connects to the slapd server using the proxy protocol over IPv4, this fills the from variable with an IPv4 address and sets the len variable to the size of the struct sockaddr_in. This is correct. The slap_listener function detects that the connection is proxied (https://git.openldap.org/openldap/openldap/-/blob/OPENLDAP_REL_ENG_2_6_10/s…) and uses the proxyp function to get the address of the LDAP client. This fills the from variable with an IPv4 or an IPv6 address (depending on whether the LDAP client used IPv4 or IPv6 to connect the reverse proxy) but does not update the len variable. The slap_listener function detects that reverse lookup is to be used (https://git.openldap.org/openldap/openldap/-/blob/OPENLDAP_REL_ENG_2_6_10/s…) and used the ldap_pvt_get_hname function to get the reverse name (https://git.openldap.org/openldap/openldap/-/blob/OPENLDAP_REL_ENG_2_6_10/s…) passing the address of the from variable, which may contain either an IPv4 or an IPv6 address, and the value of the len variable, which is equal to the size of the struct sockaddr_in. This is correct for IPv4 but not for IPv6. Either the slap_listener function or the proxyp function should update the value of the len variable. -- You are receiving this mail because: You are on the CC list for the issue.

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openldap-bugs September 2025