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/*
* ProFTPD - mod_proxy SSH disconnects
* Copyright (c) 2021 TJ Saunders
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA.
*
* As a special exemption, TJ Saunders and other respective copyright holders
* give permission to link this program with OpenSSL, and distribute the
* resulting executable, without including the source code for OpenSSL in the
* source distribution.
*/
#include "mod_proxy.h"
#include "proxy/ssh/ssh2.h"
#include "proxy/ssh/msg.h"
#include "proxy/ssh/packet.h"
#include "proxy/ssh/disconnect.h"
#if defined(PR_USE_OPENSSL)
struct disconnect_reason {
uint32_t code;
const char *explain;
const char *lang;
};
static struct disconnect_reason explanations[] = {
{ PROXY_SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT, "Host not allowed to connect", NULL },
{ PROXY_SSH_DISCONNECT_PROTOCOL_ERROR, "Protocol error", NULL },
{ PROXY_SSH_DISCONNECT_KEY_EXCHANGE_FAILED, "Key exchange failed", NULL },
{ PROXY_SSH_DISCONNECT_MAC_ERROR, "MAC error", NULL },
{ PROXY_SSH_DISCONNECT_COMPRESSION_ERROR, "Compression error", NULL },
{ PROXY_SSH_DISCONNECT_SERVICE_NOT_AVAILABLE, "Requested service not available", NULL },
{ PROXY_SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED, "Protocol version not supported", NULL },
{ PROXY_SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE, "Host key not verifiable", NULL },
{ PROXY_SSH_DISCONNECT_CONNECTION_LOST, "Connection lost", NULL },
{ PROXY_SSH_DISCONNECT_BY_APPLICATION, "Application disconnected", NULL },
{ PROXY_SSH_DISCONNECT_TOO_MANY_CONNECTIONS, "Too many connections", NULL },
{ PROXY_SSH_DISCONNECT_AUTH_CANCELLED_BY_USER, "Authentication cancelled by user", NULL },
{ PROXY_SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE, "No other authentication mechanisms available", NULL },
{ PROXY_SSH_DISCONNECT_ILLEGAL_USER_NAME, "Illegal user name", NULL },
{ 0, NULL, NULL }
};
static const char *trace_channel = "proxy.ssh.disconnect";
const char *proxy_ssh_disconnect_get_text(uint32_t reason_code) {
register unsigned int i;
for (i = 0; explanations[i].explain; i++) {
if (explanations[i].code == reason_code) {
return explanations[i].explain;
}
}
errno = ENOENT;
return NULL;
}
void proxy_ssh_disconnect_send(pool *p, conn_t *conn, uint32_t reason,
const char *explain, const char *file, int lineno, const char *func) {
struct proxy_ssh_packet *pkt;
const char *lang = "en-US";
unsigned char *buf, *ptr;
uint32_t buflen, bufsz, len = 0;
/* Send the server a DISCONNECT mesg. */
pkt = proxy_ssh_packet_create(p);
buflen = bufsz = 1024;
ptr = buf = palloc(pkt->pool, bufsz);
if (explain == NULL) {
register unsigned int i;
for (i = 0; explanations[i].explain; i++) {
if (explanations[i].code == reason) {
explain = explanations[i].explain;
lang = explanations[i].lang;
if (lang == NULL) {
lang = "en-US";
}
break;
}
}
if (explain == NULL) {
explain = "Unknown reason";
}
} else {
lang = "en-US";
}
if (strlen(func) > 0) {
pr_trace_msg(trace_channel, 9, "disconnecting (%s) [at %s:%d:%s()]",
explain, file, lineno, func);
} else {
pr_trace_msg(trace_channel, 9, "disconnecting (%s) [at %s:%d]", explain,
file, lineno);
}
len += proxy_ssh_msg_write_byte(&buf, &buflen, PROXY_SSH_MSG_DISCONNECT);
len += proxy_ssh_msg_write_int(&buf, &buflen, reason);
len += proxy_ssh_msg_write_string(&buf, &buflen, explain);
len += proxy_ssh_msg_write_string(&buf, &buflen, lang);
pkt->payload = ptr;
pkt->payload_len = len;
(void) pr_log_writefile(proxy_logfd, MOD_PROXY_VERSION,
"disconnecting %s (%s)", pr_netaddr_get_ipstr(conn->remote_addr), explain);
/* Explicitly set a short poll timeout of 2 secs. */
proxy_ssh_packet_set_poll_timeout(2, 0);
if (proxy_ssh_packet_write(conn, pkt) < 0) {
int xerrno = errno;
pr_trace_msg(trace_channel, 12,
"error writing DISCONNECT message: %s", strerror(xerrno));
}
destroy_pool(pkt->pool);
}
void proxy_ssh_disconnect_conn(conn_t *conn, uint32_t reason,
const char *explain, const char *file, int lineno, const char *func) {
proxy_ssh_disconnect_send(proxy_pool, conn, reason, explain, file, lineno,
func);
#if defined(PR_DEVEL_COREDUMP)
pr_session_end(PR_SESS_END_FL_NOEXIT);
abort();
#else
pr_session_disconnect(&proxy_module, PR_SESS_DISCONNECT_BY_APPLICATION, NULL);
#endif /* PR_DEVEL_COREDUMP */
}
#endif /* PR_USE_OPENSSL */
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