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/* ssh-base.c
* ssh-base has base utility functions to connect to hosts via ssh
*
* Copyright 2016, Dario Lombardo
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#define WS_LOG_DOMAIN LOG_DOMAIN_EXTCAP
#include "ssh-base.h"
#include <extcap/extcap-base.h>
#include <string.h>
#include <libssh/callbacks.h>
#include <ws_attributes.h>
#include <wsutil/wslog.h>
static void extcap_log(int priority _U_, const char *function, const char *buffer, void *userdata _U_)
{
ws_debug("[%s] %s", function, buffer);
}
void add_libssh_info(extcap_parameters * extcap_conf)
{
extcap_base_set_compiled_with(extcap_conf, "libssh version %s", SSH_STRINGIFY(LIBSSH_VERSION));
extcap_base_set_running_with(extcap_conf, "libssh version %s", ssh_version(0));
}
ssh_session create_ssh_connection(const ssh_params_t* ssh_params, char** err_info)
{
ssh_session sshs;
char* username = NULL;
unsigned port;
/* Open session and set options */
sshs = ssh_new();
if (sshs == NULL) {
*err_info = g_strdup("Can't create ssh session");
return NULL;
}
if (!ssh_params->host) {
*err_info = g_strdup("Hostname needed");
goto failure;
}
if (ssh_options_set(sshs, SSH_OPTIONS_HOST, ssh_params->host)) {
*err_info = ws_strdup_printf("Can't set the host: %s", ssh_params->host);
goto failure;
}
/* Load the configurations already present in the system configuration file. */
/* They will be overwritten by the user-provided configurations. */
if (ssh_options_parse_config(sshs, NULL) != 0) {
*err_info = g_strdup("Unable to load the configuration file");
goto failure;
}
if (ssh_params->debug) {
int debug_level = SSH_LOG_INFO;
ssh_options_set(sshs, SSH_OPTIONS_LOG_VERBOSITY, &debug_level);
ssh_set_log_callback(extcap_log);
}
if (ssh_params->port != 0) {
port = ssh_params->port;
if (ssh_options_set(sshs, SSH_OPTIONS_PORT, &port)) {
*err_info = ws_strdup_printf("Can't set the port: %u", port);
goto failure;
}
}
if (ssh_params->proxycommand) {
if (ssh_options_set(sshs, SSH_OPTIONS_PROXYCOMMAND, ssh_params->proxycommand)) {
*err_info = ws_strdup_printf("Can't set the ProxyCommand: %s", ssh_params->proxycommand);
goto failure;
}
}
if (ssh_params->username) {
if (ssh_options_set(sshs, SSH_OPTIONS_USER, ssh_params->username)) {
*err_info = ws_strdup_printf("Can't set the username: %s", ssh_params->username);
goto failure;
}
}
ssh_options_get(sshs, SSH_OPTIONS_USER, &username);
ssh_options_get_port(sshs, &port);
ws_log(LOG_DOMAIN_CAPCHILD, LOG_LEVEL_INFO, "Opening ssh connection to %s@%s:%u", username,
ssh_params->host, port);
ssh_string_free_char(username);
/* Connect to server */
if (ssh_connect(sshs) != SSH_OK) {
*err_info = ws_strdup_printf("Connection error: %s", ssh_get_error(sshs));
goto failure;
}
/* If a public key path has been provided, try to authenticate using it */
if (ssh_params->sshkey_path) {
ssh_key pkey = ssh_key_new();
int ret;
ws_info("Connecting using public key in %s...", ssh_params->sshkey_path);
ret = ssh_pki_import_privkey_file(ssh_params->sshkey_path, ssh_params->sshkey_passphrase, NULL, NULL, &pkey);
if (ret == SSH_OK) {
if (ssh_userauth_publickey(sshs, NULL, pkey) == SSH_AUTH_SUCCESS) {
ws_info("done");
ssh_key_free(pkey);
return sshs;
}
}
ssh_key_free(pkey);
ws_info("failed (%s)", ssh_get_error(sshs));
}
/* Workaround: it may happen that libssh closes socket in meantime and any next ssh_ call fails so we should detect it in advance */
if (ssh_get_fd(sshs) != (socket_t)-1) {
/* If a password has been provided and all previous attempts failed, try to use it */
if (ssh_params->password) {
ws_info("Connecting using password...");
if (ssh_userauth_password(sshs, ssh_params->username, ssh_params->password) == SSH_AUTH_SUCCESS) {
ws_info("done");
return sshs;
}
ws_info("failed");
}
} else {
ws_info("ssh connection closed before password authentication");
}
/* Workaround: it may happen that libssh closes socket in meantime and any next ssh_ call fails so we should detect it in advance */
if (ssh_get_fd(sshs) != (socket_t)-1) {
/* Try to authenticate using standard public key */
ws_info("Connecting using standard public key...");
if (ssh_userauth_publickey_auto(sshs, NULL, NULL) == SSH_AUTH_SUCCESS) {
ws_info("done");
return sshs;
}
ws_info("failed");
} else {
ws_info("ssh connection closed before public key authentication");
}
*err_info = ws_strdup_printf("Can't find a valid authentication. Disconnecting.");
/* All authentication failed. Disconnect and return */
ssh_disconnect(sshs);
failure:
ssh_free(sshs);
return NULL;
}
int ssh_channel_printf(ssh_channel channel, const char* fmt, ...)
{
char* buf;
va_list arg;
int ret = EXIT_SUCCESS;
va_start(arg, fmt);
buf = ws_strdup_vprintf(fmt, arg);
ws_debug("%s", buf);
if (ssh_channel_write(channel, buf, (uint32_t)strlen(buf)) == SSH_ERROR)
ret = EXIT_FAILURE;
va_end(arg);
g_free(buf);
return ret;
}
void ssh_cleanup(ssh_session* sshs, ssh_channel* channel)
{
if (*channel) {
ssh_channel_send_eof(*channel);
ssh_channel_close(*channel);
ssh_channel_free(*channel);
*channel = NULL;
}
if (*sshs) {
ssh_disconnect(*sshs);
ssh_free(*sshs);
*sshs = NULL;
}
}
ssh_params_t* ssh_params_new(void)
{
return g_new0(ssh_params_t, 1);
}
void ssh_params_free(ssh_params_t* ssh_params)
{
if (!ssh_params)
return;
g_free(ssh_params->host);
g_free(ssh_params->username);
g_free(ssh_params->password);
g_free(ssh_params->sshkey_path);
g_free(ssh_params->sshkey_passphrase);
g_free(ssh_params->proxycommand);
g_free(ssh_params);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 8
* tab-width: 8
* indent-tabs-mode: t
* End:
*
* vi: set shiftwidth=8 tabstop=8 noexpandtab:
* :indentSize=8:tabSize=8:noTabs=false:
*/
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