add SOCKS4A support to nc(1)'s proxy (-X) mode

SOCKS4A is a fairly obscure extension to the olde SOCKS4 protocol that
allows passing the destination as a string rather than a literal IPv4
address, which is the only thing that vanilla SOCKS4 supports.

The motivation for adding something so niche is to test the SOCKS4A
server code in ssh(1)'s dynamic forwarding (-D) support.

ok tb@

1 files changed, 3 insertions, 1 deletions

diff --git a/src/usr.bin/nc/netcat.c b/src/usr.bin/nc/netcat.c
index 67beb10d0a..bf4a7ccf12 100644
--- a/src/usr.bin/nc/netcat.c
+++ b/src/usr.bin/nc/netcat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: netcat.c,v 1.230 2025/05/14 08:56:41 tb Exp $ */
+/* $OpenBSD: netcat.c,v 1.231 2025/05/21 08:41:35 djm Exp $ */
 /*
  * Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
  * Copyright (c) 2015 Bob Beck.  All rights reserved.
@@ -190,6 +190,8 @@ main(int argc, char *argv[])
                                 socksv = -1; /* HTTP proxy CONNECT */
                         else if (strcmp(optarg, "4") == 0)
                                 socksv = 4; /* SOCKS v.4 */
+                        else if (strcasecmp(optarg, "4A") == 0)
+                                socksv = 44; /* SOCKS v.4A */
                         else if (strcmp(optarg, "5") == 0)
                                 socksv = 5; /* SOCKS v.5 */
                         else