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ssh: Add support for userauth banner.
The new libssh2_userauth_banner API allows to get an optional userauth banner sent with SSH_MSG_USERAUTH_BANNER packet by the server. Closes issue 610
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7 files changed

Lines changed: 118 additions & 2 deletions

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‎vendor/libssh2/docs/CMakeLists.txt‎

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@@ -193,6 +193,7 @@ set(MAN_PAGES
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libssh2_trace.3
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libssh2_trace_sethandler.3
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libssh2_userauth_authenticated.3
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libssh2_userauth_banner.3
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libssh2_userauth_hostbased_fromfile.3
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libssh2_userauth_hostbased_fromfile_ex.3
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libssh2_userauth_keyboard_interactive.3

‎vendor/libssh2/docs/Makefile.am‎

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@@ -163,6 +163,7 @@ dist_man_MANS = \
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libssh2_trace.3 \
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libssh2_trace_sethandler.3 \
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libssh2_userauth_authenticated.3 \
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libssh2_userauth_banner.3 \
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libssh2_userauth_hostbased_fromfile.3 \
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libssh2_userauth_hostbased_fromfile_ex.3 \
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libssh2_userauth_keyboard_interactive.3 \

‎vendor/libssh2/docs/libssh2_userauth_banner.3‎

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@@ -0,0 +1,30 @@
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.TH libssh2_userauth_banner 3 "1 Jun 2021" "libssh2 1.9.0" "libssh2 manual"
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.SH NAME
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libssh2_userauth_banner - get the server's userauth banner message
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.SH SYNOPSIS
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.nf
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#include <libssh2.h>
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int
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libssh2_userauth_banner(LIBSSH2_SESSION *session, char **banner);
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.SH DESCRIPTION
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\fIsession\fP - Session instance as returned by
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.BR libssh2_session_init_ex(3)
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\fIbanner\fP - Should point to a pointer that gets filled with banner message.
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After an authentication has been attempted, such as a
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\fBSSH_USERAUTH_NONE\fP request sent by
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.BR libssh2_userauth_list(3) ,
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this function can be called to retrieve the userauth banner sent by
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the server. If no such banner is sent, or if an authentication has not
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yet been attempted, returns LIBSSH2_ERROR_MISSING_USERAUTH_BANNER.
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.SH RETURN VALUE
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On success returns 0 and an UTF-8 NUL-terminated string is stored in the
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\fIbanner\fP. This string is internally managed by libssh2 and will be
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deallocated upon session termination.
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On failure returns
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LIBSSH2_ERROR_MISSING_USERAUTH_BANNER.
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.SH SEE ALSO
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.BR libssh2_session_init_ex(3),
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.BR libssh2_userauth_list(3)

‎vendor/libssh2/include/libssh2.h‎

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@@ -507,6 +507,7 @@ typedef struct _LIBSSH2_POLLFD {
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#define LIBSSH2_ERROR_CHANNEL_WINDOW_FULL -47
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#define LIBSSH2_ERROR_KEYFILE_AUTH_FAILED -48
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#define LIBSSH2_ERROR_RANDGEN -49
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#define LIBSSH2_ERROR_MISSING_USERAUTH_BANNER -50
510511

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/* this is a define to provide the old (<= 1.2.7) name */
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#define LIBSSH2_ERROR_BANNER_NONE LIBSSH2_ERROR_BANNER_RECV
@@ -615,6 +616,8 @@ LIBSSH2_API const char *libssh2_session_banner_get(LIBSSH2_SESSION *session);
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LIBSSH2_API char *libssh2_userauth_list(LIBSSH2_SESSION *session,
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const char *username,
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unsigned int username_len);
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LIBSSH2_API int libssh2_userauth_banner(LIBSSH2_SESSION *session,
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char **banner);
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LIBSSH2_API int libssh2_userauth_authenticated(LIBSSH2_SESSION *session);
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LIBSSH2_API int

‎vendor/libssh2/src/libssh2_priv.h‎

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@@ -720,6 +720,7 @@ struct _LIBSSH2_SESSION
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libssh2_nonblocking_states userauth_list_state;
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unsigned char *userauth_list_data;
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size_t userauth_list_data_len;
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char *userauth_banner;
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packet_requirev_state_t userauth_list_packet_requirev_state;
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/* State variables used in libssh2_userauth_password_ex() */

‎vendor/libssh2/src/session.c‎

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Original file line numberDiff line numberDiff line change
@@ -994,6 +994,9 @@ session_free(LIBSSH2_SESSION *session)
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if(session->userauth_list_data) {
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LIBSSH2_FREE(session, session->userauth_list_data);
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}
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if(session->userauth_banner) {
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LIBSSH2_FREE(session, session->userauth_banner);
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}
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if(session->userauth_pswd_data) {
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LIBSSH2_FREE(session, session->userauth_pswd_data);
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}

‎vendor/libssh2/src/userauth.c‎

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Original file line numberDiff line numberDiff line change
@@ -63,11 +63,13 @@
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static char *userauth_list(LIBSSH2_SESSION *session, const char *username,
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unsigned int username_len)
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{
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static const unsigned char reply_codes[3] =
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{ SSH_MSG_USERAUTH_SUCCESS, SSH_MSG_USERAUTH_FAILURE, 0 };
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unsigned char reply_codes[4] =
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{ SSH_MSG_USERAUTH_SUCCESS, SSH_MSG_USERAUTH_FAILURE,
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SSH_MSG_USERAUTH_BANNER, 0 };
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/* packet_type(1) + username_len(4) + service_len(4) +
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service(14)"ssh-connection" + method_len(4) = 27 */
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unsigned long methods_len;
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unsigned int banner_len;
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unsigned char *s;
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int rc;
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@@ -134,6 +136,57 @@ static char *userauth_list(LIBSSH2_SESSION *session, const char *username,
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return NULL;
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}
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if(session->userauth_list_data[0] == SSH_MSG_USERAUTH_BANNER) {
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if(session->userauth_list_data_len < 5) {
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LIBSSH2_FREE(session, session->userauth_list_data);
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session->userauth_list_data = NULL;
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_libssh2_error(session, LIBSSH2_ERROR_PROTO,
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"Unexpected packet size");
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return NULL;
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}
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banner_len = _libssh2_ntohu32(session->userauth_list_data + 1);
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if(banner_len >= session->userauth_list_data_len - 5) {
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LIBSSH2_FREE(session, session->userauth_list_data);
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session->userauth_list_data = NULL;
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_libssh2_error(session, LIBSSH2_ERROR_OUT_OF_BOUNDARY,
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"Unexpected userauth banner size");
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return NULL;
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}
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session->userauth_banner = LIBSSH2_ALLOC(session, banner_len);
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if(!session->userauth_banner) {
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LIBSSH2_FREE(session, session->userauth_list_data);
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session->userauth_list_data = NULL;
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_libssh2_error(session, LIBSSH2_ERROR_ALLOC,
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"Unable to allocate memory for userauth_banner");
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return NULL;
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}
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memmove(session->userauth_banner, session->userauth_list_data + 5,
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banner_len);
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session->userauth_banner[banner_len] = '\0';
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_libssh2_debug(session, LIBSSH2_TRACE_AUTH,
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"Banner: %s",
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session->userauth_banner);
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LIBSSH2_FREE(session, session->userauth_list_data);
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session->userauth_list_data = NULL;
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/* SSH_MSG_USERAUTH_BANNER has been handled */
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reply_codes[2] = 0;
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rc = _libssh2_packet_requirev(session, reply_codes,
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&session->userauth_list_data,
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&session->userauth_list_data_len, 0,
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NULL, 0,
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&session->userauth_list_packet_requirev_state);
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if(rc == LIBSSH2_ERROR_EAGAIN) {
179+
_libssh2_error(session, LIBSSH2_ERROR_EAGAIN,
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"Would block requesting userauth list");
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return NULL;
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}
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else if(rc || (session->userauth_list_data_len < 1)) {
184+
_libssh2_error(session, rc, "Failed getting response");
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session->userauth_list_state = libssh2_NB_state_idle;
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return NULL;
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}
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}
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if(session->userauth_list_data[0] == SSH_MSG_USERAUTH_SUCCESS) {
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/* Wow, who'dve thought... */
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_libssh2_error(session, LIBSSH2_ERROR_NONE, "No error");
@@ -189,6 +242,30 @@ libssh2_userauth_list(LIBSSH2_SESSION * session, const char *user,
189242
return ptr;
190243
}
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/* libssh2_userauth_banner
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*
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* Retrieve banner message from server, if available.
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* When no such message is sent by server or if no authentication attempt has
249+
* been made, this function returns LIBSSH2_ERROR_MISSING_AUTH_BANNER.
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*/
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LIBSSH2_API int
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libssh2_userauth_banner(LIBSSH2_SESSION *session, char **banner)
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{
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if(NULL == session)
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return LIBSSH2_ERROR_MISSING_USERAUTH_BANNER;
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if(!session->userauth_banner) {
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return _libssh2_error(session,
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LIBSSH2_ERROR_MISSING_USERAUTH_BANNER,
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"Missing userauth banner");
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}
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if(banner != NULL)
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*banner = session->userauth_banner;
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return LIBSSH2_ERROR_NONE;
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}
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/*
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* libssh2_userauth_authenticated
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*

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