mirror of
https://git.tartarus.org/simon/putty.git
synced 2025-01-09 17:38:00 +00:00
0f405ae8a3
If the SSH socket is readable, GTK will preferentially give us a callback to read from it rather than calling its idle functions. That means the ssh->in_raw bufchain can just keep accumulating data, and the callback that gets the BPP to take data back off that bufchain will never be called at all. The solution is to use sk_set_frozen after a certain point, to stop reading further data from the socket (and, more importantly, disable GTK's I/O callback for that fd) until we've had a chance to process some backlog, and then unfreeze the socket again afterwards. Annoyingly, that means adding a _second_ 'frozen' flag to Ssh, because the one we already had has exactly the wrong semantics - it prevents us from _processing_ our backlog, which is the last thing we want if the entire problem is that we need that backlog to get smaller! So now there are two frozen flags, and a big comment explaining the difference.
476 lines
14 KiB
C
476 lines
14 KiB
C
/*
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* Top-level code for SSH server implementation.
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*/
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#include <assert.h>
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#include <stddef.h>
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#include "putty.h"
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#include "ssh.h"
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#include "sshbpp.h"
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#include "sshppl.h"
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#include "sshserver.h"
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#ifndef NO_GSSAPI
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#include "sshgssc.h"
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#include "sshgss.h"
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#endif
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struct Ssh { int dummy; };
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typedef struct server server;
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struct server {
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bufchain in_raw, out_raw;
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IdempotentCallback ic_out_raw;
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bufchain dummy_user_input; /* we never put anything on this */
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PacketLogSettings pls;
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LogContext *logctx;
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struct DataTransferStats stats;
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int remote_bugs;
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Socket *socket;
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Plug plug;
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int conn_throttle_count;
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bool frozen;
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Conf *conf;
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ssh_key *const *hostkeys;
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int nhostkeys;
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RSAKey *hostkey1;
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AuthPolicy *authpolicy;
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const SftpServerVtable *sftpserver_vt;
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Seat seat;
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Ssh ssh;
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struct ssh_version_receiver version_receiver;
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BinaryPacketProtocol *bpp;
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PacketProtocolLayer *base_layer;
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ConnectionLayer *cl;
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struct ssh_connection_shared_gss_state gss_state;
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};
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static void ssh_server_free_callback(void *vsrv);
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static void server_got_ssh_version(struct ssh_version_receiver *rcv,
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int major_version);
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static void server_connect_bpp(server *srv);
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static void server_bpp_output_raw_data_callback(void *vctx);
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void share_activate(ssh_sharing_state *sharestate,
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const char *server_verstring) {}
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void ssh_connshare_provide_connlayer(ssh_sharing_state *sharestate,
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ConnectionLayer *cl) {}
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int share_ndownstreams(ssh_sharing_state *sharestate) { return 0; }
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void share_got_pkt_from_server(ssh_sharing_connstate *cs, int type,
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const void *vpkt, int pktlen) {}
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void share_setup_x11_channel(ssh_sharing_connstate *cs, share_channel *chan,
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unsigned upstream_id, unsigned server_id,
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unsigned server_currwin, unsigned server_maxpkt,
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unsigned client_adjusted_window,
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const char *peer_addr, int peer_port, int endian,
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int protomajor, int protominor,
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const void *initial_data, int initial_len) {}
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Channel *agentf_new(SshChannel *c) { return NULL; }
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bool agent_exists(void) { return false; }
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void ssh_got_exitcode(Ssh *ssh, int exitcode) {}
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mainchan *mainchan_new(
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PacketProtocolLayer *ppl, ConnectionLayer *cl, Conf *conf,
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int term_width, int term_height, int is_simple, SshChannel **sc_out)
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{ return NULL; }
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void mainchan_get_specials(
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mainchan *mc, add_special_fn_t add_special, void *ctx) {}
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void mainchan_special_cmd(mainchan *mc, SessionSpecialCode code, int arg) {}
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void mainchan_terminal_size(mainchan *mc, int width, int height) {}
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/* Seat functions to ensure we don't get choosy about crypto - as the
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* server, it's not up to us to give user warnings */
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static int server_confirm_weak_crypto_primitive(
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Seat *seat, const char *algtype, const char *algname,
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void (*callback)(void *ctx, int result), void *ctx) { return 1; }
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static int server_confirm_weak_cached_hostkey(
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Seat *seat, const char *algname, const char *betteralgs,
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void (*callback)(void *ctx, int result), void *ctx) { return 1; }
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static const SeatVtable server_seat_vt = {
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nullseat_output,
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nullseat_eof,
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nullseat_get_userpass_input,
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nullseat_notify_remote_exit,
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nullseat_connection_fatal,
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nullseat_update_specials_menu,
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nullseat_get_ttymode,
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nullseat_set_busy_status,
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nullseat_verify_ssh_host_key,
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server_confirm_weak_crypto_primitive,
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server_confirm_weak_cached_hostkey,
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nullseat_is_never_utf8,
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nullseat_echoedit_update,
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nullseat_get_x_display,
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nullseat_get_windowid,
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nullseat_get_window_pixel_size,
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};
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static void server_socket_log(Plug *plug, int type, SockAddr *addr, int port,
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const char *error_msg, int error_code)
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{
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/* server *srv = container_of(plug, server, plug); */
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/* FIXME */
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}
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static void server_closing(Plug *plug, const char *error_msg, int error_code,
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bool calling_back)
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{
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server *srv = container_of(plug, server, plug);
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if (error_msg) {
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ssh_remote_error(&srv->ssh, "Network error: %s", error_msg);
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} else if (srv->bpp) {
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srv->bpp->input_eof = true;
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queue_idempotent_callback(&srv->bpp->ic_in_raw);
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}
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}
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static void server_receive(Plug *plug, int urgent, char *data, int len)
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{
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server *srv = container_of(plug, server, plug);
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/* Log raw data, if we're in that mode. */
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if (srv->logctx)
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log_packet(srv->logctx, PKT_INCOMING, -1, NULL, data, len,
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0, NULL, NULL, 0, NULL);
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bufchain_add(&srv->in_raw, data, len);
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if (!srv->frozen && srv->bpp)
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queue_idempotent_callback(&srv->bpp->ic_in_raw);
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}
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static void server_sent(Plug *plug, int bufsize)
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{
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#ifdef FIXME
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server *srv = container_of(plug, server, plug);
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/*
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* If the send backlog on the SSH socket itself clears, we should
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* unthrottle the whole world if it was throttled. Also trigger an
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* extra call to the consumer of the BPP's output, to try to send
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* some more data off its bufchain.
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*/
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if (bufsize < SSH_MAX_BACKLOG) {
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srv_throttle_all(srv, 0, bufsize);
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queue_idempotent_callback(&srv->ic_out_raw);
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}
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#endif
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}
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LogContext *ssh_get_logctx(Ssh *ssh)
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{
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server *srv = container_of(ssh, server, ssh);
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return srv->logctx;
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}
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void ssh_throttle_conn(Ssh *ssh, int adjust)
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{
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server *srv = container_of(ssh, server, ssh);
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int old_count = srv->conn_throttle_count;
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bool frozen;
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srv->conn_throttle_count += adjust;
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assert(srv->conn_throttle_count >= 0);
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if (srv->conn_throttle_count && !old_count) {
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frozen = true;
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} else if (!srv->conn_throttle_count && old_count) {
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frozen = false;
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} else {
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return; /* don't change current frozen state */
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}
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srv->frozen = frozen;
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if (srv->socket) {
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sk_set_frozen(srv->socket, frozen);
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/*
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* Now process any SSH connection data that was stashed in our
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* queue while we were frozen.
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*/
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queue_idempotent_callback(&srv->bpp->ic_in_raw);
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}
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}
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void ssh_conn_processed_data(Ssh *ssh)
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{
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/* FIXME: we could add the same check_frozen_state system as we
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* have in ssh.c, but because that was originally added to work
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* around a peculiarity of the GUI event loop, I haven't yet. */
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}
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static const PlugVtable ssh_server_plugvt = {
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server_socket_log,
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server_closing,
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server_receive,
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server_sent,
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NULL
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};
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Plug *ssh_server_plug(
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Conf *conf, ssh_key *const *hostkeys, int nhostkeys,
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RSAKey *hostkey1, AuthPolicy *authpolicy, LogPolicy *logpolicy,
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const SftpServerVtable *sftpserver_vt)
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{
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server *srv = snew(server);
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memset(srv, 0, sizeof(server));
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srv->plug.vt = &ssh_server_plugvt;
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srv->conf = conf_copy(conf);
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srv->logctx = log_init(logpolicy, conf);
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conf_set_bool(srv->conf, CONF_ssh_no_shell, true);
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srv->nhostkeys = nhostkeys;
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srv->hostkeys = hostkeys;
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srv->hostkey1 = hostkey1;
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srv->authpolicy = authpolicy;
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srv->sftpserver_vt = sftpserver_vt;
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srv->seat.vt = &server_seat_vt;
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bufchain_init(&srv->in_raw);
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bufchain_init(&srv->out_raw);
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bufchain_init(&srv->dummy_user_input);
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/* FIXME: replace with sensible */
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srv->gss_state.libs = snew(struct ssh_gss_liblist);
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srv->gss_state.libs->nlibraries = 0;
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return &srv->plug;
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}
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void ssh_server_start(Plug *plug, Socket *socket)
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{
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server *srv = container_of(plug, server, plug);
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const char *our_protoversion;
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if (srv->hostkey1 && srv->nhostkeys) {
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our_protoversion = "1.99"; /* offer both SSH-1 and SSH-2 */
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} else if (srv->hostkey1) {
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our_protoversion = "1.5"; /* SSH-1 only */
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} else {
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assert(srv->nhostkeys);
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our_protoversion = "2.0"; /* SSH-2 only */
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}
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srv->socket = socket;
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srv->ic_out_raw.fn = server_bpp_output_raw_data_callback;
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srv->ic_out_raw.ctx = srv;
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srv->version_receiver.got_ssh_version = server_got_ssh_version;
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srv->bpp = ssh_verstring_new(
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srv->conf, srv->logctx, false /* bare_connection */,
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our_protoversion, &srv->version_receiver,
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true, "Uppity");
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server_connect_bpp(srv);
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queue_idempotent_callback(&srv->bpp->ic_in_raw);
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}
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static void ssh_server_free_callback(void *vsrv)
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{
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server *srv = (server *)vsrv;
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bufchain_clear(&srv->in_raw);
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bufchain_clear(&srv->out_raw);
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bufchain_clear(&srv->dummy_user_input);
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sk_close(srv->socket);
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if (srv->bpp)
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ssh_bpp_free(srv->bpp);
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delete_callbacks_for_context(srv);
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conf_free(srv->conf);
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log_free(srv->logctx);
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sfree(srv->gss_state.libs); /* FIXME: replace with sensible */
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sfree(srv);
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server_instance_terminated();
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}
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static void server_connect_bpp(server *srv)
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{
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srv->bpp->ssh = &srv->ssh;
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srv->bpp->in_raw = &srv->in_raw;
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srv->bpp->out_raw = &srv->out_raw;
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bufchain_set_callback(srv->bpp->out_raw, &srv->ic_out_raw);
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srv->bpp->pls = &srv->pls;
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srv->bpp->logctx = srv->logctx;
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srv->bpp->remote_bugs = srv->remote_bugs;
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/* Servers don't really have a notion of 'unexpected' connection
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* closure. The client is free to close if it likes. */
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srv->bpp->expect_close = true;
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}
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static void server_connect_ppl(server *srv, PacketProtocolLayer *ppl)
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{
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ppl->bpp = srv->bpp;
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ppl->user_input = &srv->dummy_user_input;
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ppl->logctx = srv->logctx;
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ppl->ssh = &srv->ssh;
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ppl->seat = &srv->seat;
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ppl->remote_bugs = srv->remote_bugs;
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}
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static void server_bpp_output_raw_data_callback(void *vctx)
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{
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server *srv = (server *)vctx;
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if (!srv->socket)
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return;
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while (bufchain_size(&srv->out_raw) > 0) {
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void *data;
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int len, backlog;
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bufchain_prefix(&srv->out_raw, &data, &len);
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if (srv->logctx)
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log_packet(srv->logctx, PKT_OUTGOING, -1, NULL, data, len,
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0, NULL, NULL, 0, NULL);
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backlog = sk_write(srv->socket, data, len);
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bufchain_consume(&srv->out_raw, len);
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if (backlog > SSH_MAX_BACKLOG) {
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#ifdef FIXME
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ssh_throttle_all(ssh, 1, backlog);
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#endif
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return;
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}
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}
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#ifdef FIXME
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if (ssh->pending_close) {
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sk_close(ssh->s);
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ssh->s = NULL;
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}
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#endif
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}
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#define LOG_FORMATTED_MSG(logctx, fmt) do \
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{ \
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va_list ap; \
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va_start(ap, fmt); \
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logeventvf(logctx, fmt, ap); \
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va_end(ap); \
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} while (0)
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void ssh_remote_error(Ssh *ssh, const char *fmt, ...)
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{
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server *srv = container_of(ssh, server, ssh);
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LOG_FORMATTED_MSG(srv->logctx, fmt);
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queue_toplevel_callback(ssh_server_free_callback, srv);
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}
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void ssh_remote_eof(Ssh *ssh, const char *fmt, ...)
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{
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server *srv = container_of(ssh, server, ssh);
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LOG_FORMATTED_MSG(srv->logctx, fmt);
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queue_toplevel_callback(ssh_server_free_callback, srv);
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}
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void ssh_proto_error(Ssh *ssh, const char *fmt, ...)
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{
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server *srv = container_of(ssh, server, ssh);
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LOG_FORMATTED_MSG(srv->logctx, fmt);
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queue_toplevel_callback(ssh_server_free_callback, srv);
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}
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void ssh_sw_abort(Ssh *ssh, const char *fmt, ...)
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{
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server *srv = container_of(ssh, server, ssh);
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LOG_FORMATTED_MSG(srv->logctx, fmt);
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queue_toplevel_callback(ssh_server_free_callback, srv);
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}
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void ssh_user_close(Ssh *ssh, const char *fmt, ...)
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{
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server *srv = container_of(ssh, server, ssh);
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LOG_FORMATTED_MSG(srv->logctx, fmt);
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queue_toplevel_callback(ssh_server_free_callback, srv);
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}
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static void server_got_ssh_version(struct ssh_version_receiver *rcv,
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int major_version)
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{
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server *srv = container_of(rcv, server, version_receiver);
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BinaryPacketProtocol *old_bpp;
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PacketProtocolLayer *connection_layer;
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old_bpp = srv->bpp;
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srv->remote_bugs = ssh_verstring_get_bugs(old_bpp);
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if (major_version == 2) {
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PacketProtocolLayer *userauth_layer, *transport_child_layer;
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srv->bpp = ssh2_bpp_new(srv->logctx, &srv->stats, true);
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server_connect_bpp(srv);
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connection_layer = ssh2_connection_new(
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&srv->ssh, NULL, false, srv->conf,
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ssh_verstring_get_local(old_bpp), &srv->cl);
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ssh2connection_server_configure(connection_layer, srv->sftpserver_vt);
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server_connect_ppl(srv, connection_layer);
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if (conf_get_bool(srv->conf, CONF_ssh_no_userauth)) {
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userauth_layer = NULL;
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transport_child_layer = connection_layer;
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} else {
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userauth_layer = ssh2_userauth_server_new(
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connection_layer, srv->authpolicy);
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server_connect_ppl(srv, userauth_layer);
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transport_child_layer = userauth_layer;
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}
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srv->base_layer = ssh2_transport_new(
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srv->conf, NULL, 0, NULL,
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ssh_verstring_get_remote(old_bpp),
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ssh_verstring_get_local(old_bpp),
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&srv->gss_state, &srv->stats, transport_child_layer, true);
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ssh2_transport_provide_hostkeys(
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srv->base_layer, srv->hostkeys, srv->nhostkeys);
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if (userauth_layer)
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ssh2_userauth_server_set_transport_layer(
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userauth_layer, srv->base_layer);
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server_connect_ppl(srv, srv->base_layer);
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} else {
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srv->bpp = ssh1_bpp_new(srv->logctx);
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server_connect_bpp(srv);
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connection_layer = ssh1_connection_new(&srv->ssh, srv->conf, &srv->cl);
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server_connect_ppl(srv, connection_layer);
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srv->base_layer = ssh1_login_server_new(
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connection_layer, srv->hostkey1, srv->authpolicy);
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server_connect_ppl(srv, srv->base_layer);
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}
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/* Connect the base layer - whichever it is - to the BPP, and set
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* up its selfptr. */
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srv->base_layer->selfptr = &srv->base_layer;
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ssh_ppl_setup_queues(srv->base_layer, &srv->bpp->in_pq, &srv->bpp->out_pq);
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#ifdef FIXME // we probably will want one of these, in the end
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srv->pinger = pinger_new(srv->conf, &srv->backend);
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#endif
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queue_idempotent_callback(&srv->bpp->ic_in_raw);
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ssh_ppl_process_queue(srv->base_layer);
|
|
|
|
ssh_bpp_free(old_bpp);
|
|
}
|