ftp:ignore-pasv-address uses proxy IP instead of server IP when behind HTTP proxy

[Gixwind]

When using lftp through an HTTP proxy (ftp:proxy) combined with ftp:ignore-pasv-address true, the PASV data connection is attempted toward the proxy's IP address instead of the original server's IP address.

Environment

• lftp 4.9.2
• HTTP proxy (Squid) with CONNECT tunneling
• FTPS explicit (AUTH TLS)

How to reproduce

1. Configure an HTTP proxy: set ftp:proxy http://proxy:3128
2. Enable ignore-pasv-address: set ftp:ignore-pasv-address true
3. Connect to an FTP server behind NAT that advertises a non-routable IP in PASV response
4. Attempt a directory listing or file transfer

Expected behavior
The data connection CONNECT request should be directed to the original server IP.

Actual behavior
lftp sends CONNECT proxy_ip:data_port instead of CONNECT server_ip:data_port because peer_sa (used as fallback when ignoring PASV address) is overwritten with the proxy's IP during TCP connection setup.

Root cause
In ftpclass.cc, Handle_PASV() replaces the PASV-advertised address with conn->peer_sa. However, when the connection goes through an HTTP proxy, peer_sa holds the proxy's address rather than the server's. The same issue affects Handle_EPSV() and Handle_EPSV_CEPR().

Suggested fix
Track the original server address separately (e.g. a server_sa field in the Connection struct), populated by resolving hostname directly via getaddrinfo at connection time when proxy_is_http is true. Use server_sa instead of peer_sa in the ignore-pasv-address code path.

Happy to provide a patch if useful.