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openssh-portable/serverloop.c

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/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Server main loop for handling the interactive session.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* SSH2 support by Markus Friedl.
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
RCSID("$OpenBSD: serverloop.c,v 1.63 2001/04/29 19:16:52 markus Exp $");
#include "xmalloc.h"
#include "packet.h"
#include "buffer.h"
#include "log.h"
#include "servconf.h"
#include "sshpty.h"
#include "channels.h"
#include "compat.h"
#include "ssh1.h"
#include "ssh2.h"
#include "auth.h"
#include "session.h"
#include "dispatch.h"
#include "auth-options.h"
#include "serverloop.h"
#include "misc.h"
#include "kex.h"
extern ServerOptions options;
/* XXX */
extern Kex *xxx_kex;
static Buffer stdin_buffer; /* Buffer for stdin data. */
static Buffer stdout_buffer; /* Buffer for stdout data. */
static Buffer stderr_buffer; /* Buffer for stderr data. */
static int fdin; /* Descriptor for stdin (for writing) */
static int fdout; /* Descriptor for stdout (for reading);
May be same number as fdin. */
static int fderr; /* Descriptor for stderr. May be -1. */
static long stdin_bytes = 0; /* Number of bytes written to stdin. */
static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */
static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */
static long fdout_bytes = 0; /* Number of stdout bytes read from program. */
static int stdin_eof = 0; /* EOF message received from client. */
static int fdout_eof = 0; /* EOF encountered reading from fdout. */
static int fderr_eof = 0; /* EOF encountered readung from fderr. */
static int fdin_is_tty = 0; /* fdin points to a tty. */
static int connection_in; /* Connection to client (input). */
static int connection_out; /* Connection to client (output). */
static int connection_closed = 0; /* Connection to client closed. */
static u_int buffer_high; /* "Soft" max buffer size. */
/*
* This SIGCHLD kludge is used to detect when the child exits. The server
* will exit after that, as soon as forwarded connections have terminated.
*/
static pid_t child_pid; /* Pid of the child. */
static volatile int child_terminated; /* The child has terminated. */
static volatile int child_wait_status; /* Status from wait(). */
void server_init_dispatch(void);
int client_alive_timeouts = 0;
void
sigchld_handler(int sig)
{
int save_errno = errno;
pid_t wait_pid;
debug("Received SIGCHLD.");
wait_pid = wait((int *) &child_wait_status);
if (wait_pid != -1) {
if (wait_pid != child_pid)
error("Strange, got SIGCHLD and wait returned pid %d but child is %d",
wait_pid, child_pid);
if (WIFEXITED(child_wait_status) ||
WIFSIGNALED(child_wait_status))
child_terminated = 1;
}
signal(SIGCHLD, sigchld_handler);
errno = save_errno;
}
void
sigchld_handler2(int sig)
{
int save_errno = errno;
debug("Received SIGCHLD.");
child_terminated = 1;
mysignal(SIGCHLD, sigchld_handler2);
errno = save_errno;
}
/*
* Make packets from buffered stderr data, and buffer it for sending
* to the client.
*/
void
make_packets_from_stderr_data(void)
{
int len;
/* Send buffered stderr data to the client. */
while (buffer_len(&stderr_buffer) > 0 &&
packet_not_very_much_data_to_write()) {
len = buffer_len(&stderr_buffer);
if (packet_is_interactive()) {
if (len > 512)
len = 512;
} else {
/* Keep the packets at reasonable size. */
if (len > packet_get_maxsize())
len = packet_get_maxsize();
}
packet_start(SSH_SMSG_STDERR_DATA);
packet_put_string(buffer_ptr(&stderr_buffer), len);
packet_send();
buffer_consume(&stderr_buffer, len);
stderr_bytes += len;
}
}
/*
* Make packets from buffered stdout data, and buffer it for sending to the
* client.
*/
void
make_packets_from_stdout_data(void)
{
int len;
/* Send buffered stdout data to the client. */
while (buffer_len(&stdout_buffer) > 0 &&
packet_not_very_much_data_to_write()) {
len = buffer_len(&stdout_buffer);
if (packet_is_interactive()) {
if (len > 512)
len = 512;
} else {
/* Keep the packets at reasonable size. */
if (len > packet_get_maxsize())
len = packet_get_maxsize();
}
packet_start(SSH_SMSG_STDOUT_DATA);
packet_put_string(buffer_ptr(&stdout_buffer), len);
packet_send();
buffer_consume(&stdout_buffer, len);
stdout_bytes += len;
}
}
/*
* Sleep in select() until we can do something. This will initialize the
* select masks. Upon return, the masks will indicate which descriptors
* have data or can accept data. Optionally, a maximum time can be specified
* for the duration of the wait (0 = infinite).
*/
void
wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
u_int max_time_milliseconds)
{
struct timeval tv, *tvp;
int ret;
int client_alive_scheduled = 0;
/*
* if using client_alive, set the max timeout accordingly,
* and indicate that this particular timeout was for client
* alive by setting the client_alive_scheduled flag.
*
* this could be randomized somewhat to make traffic
* analysis more difficult, but we're not doing it yet.
*/
if (max_time_milliseconds == 0 && options.client_alive_interval) {
client_alive_scheduled = 1;
max_time_milliseconds = options.client_alive_interval * 1000;
} else
client_alive_scheduled = 0;
/* When select fails we restart from here. */
retry_select:
/* Allocate and update select() masks for channel descriptors. */
channel_prepare_select(readsetp, writesetp, maxfdp, 0);
if (compat20) {
/* wrong: bad condition XXX */
if (channel_not_very_much_buffered_data())
FD_SET(connection_in, *readsetp);
} else {
/*
* Read packets from the client unless we have too much
* buffered stdin or channel data.
*/
if (buffer_len(&stdin_buffer) < buffer_high &&
channel_not_very_much_buffered_data())
FD_SET(connection_in, *readsetp);
/*
* If there is not too much data already buffered going to
* the client, try to get some more data from the program.
*/
if (packet_not_very_much_data_to_write()) {
if (!fdout_eof)
FD_SET(fdout, *readsetp);
if (!fderr_eof)
FD_SET(fderr, *readsetp);
}
/*
* If we have buffered data, try to write some of that data
* to the program.
*/
if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
FD_SET(fdin, *writesetp);
}
/*
* If we have buffered packet data going to the client, mark that
* descriptor.
*/
if (packet_have_data_to_write())
FD_SET(connection_out, *writesetp);
/*
* If child has terminated and there is enough buffer space to read
* from it, then read as much as is available and exit.
*/
if (child_terminated && packet_not_very_much_data_to_write())
if (max_time_milliseconds == 0 || client_alive_scheduled)
max_time_milliseconds = 100;
if (max_time_milliseconds == 0)
tvp = NULL;
else {
tv.tv_sec = max_time_milliseconds / 1000;
tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
tvp = &tv;
}
if (tvp!=NULL)
debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds);
/* Wait for something to happen, or the timeout to expire. */
ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
if (ret == -1) {
if (errno != EINTR)
error("select: %.100s", strerror(errno));
else
goto retry_select;
}
if (ret == 0 && client_alive_scheduled) {
/* timeout, check to see how many we have had */
client_alive_timeouts++;
if (client_alive_timeouts > options.client_alive_count_max ) {
packet_disconnect(
"Timeout, your session not responding.");
} else {
/*
* send a bogus channel request with "wantreply"
* we should get back a failure
*/
int id;
id = channel_find_open();
if (id != -1) {
channel_request_start(id,
"keepalive@openssh.com", 1);
packet_send();
} else
packet_disconnect(
"No open channels after timeout!");
}
}
}
/*
* Processes input from the client and the program. Input data is stored
* in buffers and processed later.
*/
void
process_input(fd_set * readset)
{
int len;
char buf[16384];
/* Read and buffer any input data from the client. */
if (FD_ISSET(connection_in, readset)) {
len = read(connection_in, buf, sizeof(buf));
if (len == 0) {
verbose("Connection closed by remote host.");
connection_closed = 1;
if (compat20)
return;
fatal_cleanup();
} else if (len < 0) {
if (errno != EINTR && errno != EAGAIN) {
verbose("Read error from remote host: %.100s", strerror(errno));
fatal_cleanup();
}
} else {
/* Buffer any received data. */
packet_process_incoming(buf, len);
}
}
if (compat20)
return;
/* Read and buffer any available stdout data from the program. */
if (!fdout_eof && FD_ISSET(fdout, readset)) {
len = read(fdout, buf, sizeof(buf));
if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
/* do nothing */
} else if (len <= 0) {
fdout_eof = 1;
} else {
buffer_append(&stdout_buffer, buf, len);
fdout_bytes += len;
}
}
/* Read and buffer any available stderr data from the program. */
if (!fderr_eof && FD_ISSET(fderr, readset)) {
len = read(fderr, buf, sizeof(buf));
if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
/* do nothing */
} else if (len <= 0) {
fderr_eof = 1;
} else {
buffer_append(&stderr_buffer, buf, len);
}
}
}
/*
* Sends data from internal buffers to client program stdin.
*/
void
process_output(fd_set * writeset)
{
struct termios tio;
int len;
/* Write buffered data to program stdin. */
if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
len = write(fdin, buffer_ptr(&stdin_buffer),
buffer_len(&stdin_buffer));
if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
/* do nothing */
} else if (len <= 0) {
#ifdef USE_PIPES
close(fdin);
#else
if (fdin != fdout)
close(fdin);
else
shutdown(fdin, SHUT_WR); /* We will no longer send. */
#endif
fdin = -1;
} else {
/* Successful write. */
if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 &&
!(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
/*
* Simulate echo to reduce the impact of
* traffic analysis
*/
packet_send_ignore(len);
packet_send();
}
/* Consume the data from the buffer. */
buffer_consume(&stdin_buffer, len);
/* Update the count of bytes written to the program. */
stdin_bytes += len;
}
}
/* Send any buffered packet data to the client. */
if (FD_ISSET(connection_out, writeset))
packet_write_poll();
}
/*
* Wait until all buffered output has been sent to the client.
* This is used when the program terminates.
*/
void
drain_output(void)
{
/* Send any buffered stdout data to the client. */
if (buffer_len(&stdout_buffer) > 0) {
packet_start(SSH_SMSG_STDOUT_DATA);
packet_put_string(buffer_ptr(&stdout_buffer),
buffer_len(&stdout_buffer));
packet_send();
/* Update the count of sent bytes. */
stdout_bytes += buffer_len(&stdout_buffer);
}
/* Send any buffered stderr data to the client. */
if (buffer_len(&stderr_buffer) > 0) {
packet_start(SSH_SMSG_STDERR_DATA);
packet_put_string(buffer_ptr(&stderr_buffer),
buffer_len(&stderr_buffer));
packet_send();
/* Update the count of sent bytes. */
stderr_bytes += buffer_len(&stderr_buffer);
}
/* Wait until all buffered data has been written to the client. */
packet_write_wait();
}
void
process_buffered_input_packets(void)
{
dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
}
/*
* Performs the interactive session. This handles data transmission between
* the client and the program. Note that the notion of stdin, stdout, and
* stderr in this function is sort of reversed: this function writes to
* stdin (of the child program), and reads from stdout and stderr (of the
* child program).
*/
void
server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
{
fd_set *readset = NULL, *writeset = NULL;
int max_fd;
int wait_status; /* Status returned by wait(). */
pid_t wait_pid; /* pid returned by wait(). */
int waiting_termination = 0; /* Have displayed waiting close message. */
u_int max_time_milliseconds;
u_int previous_stdout_buffer_bytes;
u_int stdout_buffer_bytes;
int type;
debug("Entering interactive session.");
/* Initialize the SIGCHLD kludge. */
child_pid = pid;
child_terminated = 0;
signal(SIGCHLD, sigchld_handler);
/* Initialize our global variables. */
fdin = fdin_arg;
fdout = fdout_arg;
fderr = fderr_arg;
/* nonblocking IO */
set_nonblock(fdin);
set_nonblock(fdout);
/* we don't have stderr for interactive terminal sessions, see below */
if (fderr != -1)
set_nonblock(fderr);
if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
fdin_is_tty = 1;
connection_in = packet_get_connection_in();
connection_out = packet_get_connection_out();
previous_stdout_buffer_bytes = 0;
/* Set approximate I/O buffer size. */
if (packet_is_interactive())
buffer_high = 4096;
else
buffer_high = 64 * 1024;
/* Initialize max_fd to the maximum of the known file descriptors. */
max_fd = MAX(fdin, fdout);
if (fderr != -1)
max_fd = MAX(max_fd, fderr);
max_fd = MAX(max_fd, connection_in);
max_fd = MAX(max_fd, connection_out);
/* Initialize Initialize buffers. */
buffer_init(&stdin_buffer);
buffer_init(&stdout_buffer);
buffer_init(&stderr_buffer);
/*
* If we have no separate fderr (which is the case when we have a pty
* - there we cannot make difference between data sent to stdout and
* stderr), indicate that we have seen an EOF from stderr. This way
* we don\'t need to check the descriptor everywhere.
*/
if (fderr == -1)
fderr_eof = 1;
server_init_dispatch();
/* Main loop of the server for the interactive session mode. */
for (;;) {
/* Process buffered packets from the client. */
process_buffered_input_packets();
/*
* If we have received eof, and there is no more pending
* input data, cause a real eof by closing fdin.
*/
if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
#ifdef USE_PIPES
close(fdin);
#else
if (fdin != fdout)
close(fdin);
else
shutdown(fdin, SHUT_WR); /* We will no longer send. */
#endif
fdin = -1;
}
/* Make packets from buffered stderr data to send to the client. */
make_packets_from_stderr_data();
/*
* Make packets from buffered stdout data to send to the
* client. If there is very little to send, this arranges to
* not send them now, but to wait a short while to see if we
* are getting more data. This is necessary, as some systems
* wake up readers from a pty after each separate character.
*/
max_time_milliseconds = 0;
stdout_buffer_bytes = buffer_len(&stdout_buffer);
if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
stdout_buffer_bytes != previous_stdout_buffer_bytes) {
/* try again after a while */
max_time_milliseconds = 10;
} else {
/* Send it now. */
make_packets_from_stdout_data();
}
previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
/* Send channel data to the client. */
if (packet_not_very_much_data_to_write())
channel_output_poll();
/*
* Bail out of the loop if the program has closed its output
* descriptors, and we have no more data to send to the
* client, and there is no pending buffered data.
*/
if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
if (!channel_still_open())
break;
if (!waiting_termination) {
const char *s = "Waiting for forwarded connections to terminate...\r\n";
char *cp;
waiting_termination = 1;
buffer_append(&stderr_buffer, s, strlen(s));
/* Display list of open channels. */
cp = channel_open_message();
buffer_append(&stderr_buffer, cp, strlen(cp));
xfree(cp);
}
}
/* Sleep in select() until we can do something. */
wait_until_can_do_something(&readset, &writeset, &max_fd,
max_time_milliseconds);
/* Process any channel events. */
channel_after_select(readset, writeset);
/* Process input from the client and from program stdout/stderr. */
process_input(readset);
/* Process output to the client and to program stdin. */
process_output(writeset);
}
if (readset)
xfree(readset);
if (writeset)
xfree(writeset);
/* Cleanup and termination code. */
/* Wait until all output has been sent to the client. */
drain_output();
debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
/* Free and clear the buffers. */
buffer_free(&stdin_buffer);
buffer_free(&stdout_buffer);
buffer_free(&stderr_buffer);
/* Close the file descriptors. */
if (fdout != -1)
close(fdout);
fdout = -1;
fdout_eof = 1;
if (fderr != -1)
close(fderr);
fderr = -1;
fderr_eof = 1;
if (fdin != -1)
close(fdin);
fdin = -1;
/* Stop listening for channels; this removes unix domain sockets. */
channel_stop_listening();
/* Wait for the child to exit. Get its exit status. */
wait_pid = wait(&wait_status);
if (wait_pid == -1) {
/*
* It is possible that the wait was handled by SIGCHLD
* handler. This may result in either: this call
* returning with EINTR, or: this call returning ECHILD.
*/
if (child_terminated)
wait_status = child_wait_status;
else
packet_disconnect("wait: %.100s", strerror(errno));
} else {
/* Check if it matches the process we forked. */
if (wait_pid != pid)
error("Strange, wait returned pid %d, expected %d",
wait_pid, pid);
}
/* We no longer want our SIGCHLD handler to be called. */
signal(SIGCHLD, SIG_DFL);
/* Check if it exited normally. */
if (WIFEXITED(wait_status)) {
/* Yes, normal exit. Get exit status and send it to the client. */
debug("Command exited with status %d.", WEXITSTATUS(wait_status));
packet_start(SSH_SMSG_EXITSTATUS);
packet_put_int(WEXITSTATUS(wait_status));
packet_send();
packet_write_wait();
/*
* Wait for exit confirmation. Note that there might be
* other packets coming before it; however, the program has
* already died so we just ignore them. The client is
* supposed to respond with the confirmation when it receives
* the exit status.
*/
do {
int plen;
type = packet_read(&plen);
}
while (type != SSH_CMSG_EXIT_CONFIRMATION);
debug("Received exit confirmation.");
return;
}
/* Check if the program terminated due to a signal. */
if (WIFSIGNALED(wait_status))
packet_disconnect("Command terminated on signal %d.",
WTERMSIG(wait_status));
/* Some weird exit cause. Just exit. */
packet_disconnect("wait returned status %04x.", wait_status);
/* NOTREACHED */
}
void
server_loop2(void)
{
fd_set *readset = NULL, *writeset = NULL;
int rekeying = 0, max_fd, status;
pid_t pid;
debug("Entering interactive session for SSH2.");
mysignal(SIGCHLD, sigchld_handler2);
child_terminated = 0;
connection_in = packet_get_connection_in();
connection_out = packet_get_connection_out();
max_fd = MAX(connection_in, connection_out);
server_init_dispatch();
for (;;) {
process_buffered_input_packets();
rekeying = (xxx_kex != NULL && !xxx_kex->done);
if (!rekeying && packet_not_very_much_data_to_write())
channel_output_poll();
wait_until_can_do_something(&readset, &writeset, &max_fd,
rekeying);
if (child_terminated) {
while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
session_close_by_pid(pid, status);
child_terminated = 0;
}
if (!rekeying)
channel_after_select(readset, writeset);
process_input(readset);
if (connection_closed)
break;
process_output(writeset);
}
if (readset)
xfree(readset);
if (writeset)
xfree(writeset);
signal(SIGCHLD, SIG_DFL);
while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
session_close_by_pid(pid, status);
channel_stop_listening();
}
void
server_input_channel_failure(int type, int plen, void *ctxt)
{
debug("Got CHANNEL_FAILURE for keepalive");
/*
* reset timeout, since we got a sane answer from the client.
* even if this was generated by something other than
* the bogus CHANNEL_REQUEST we send for keepalives.
*/
client_alive_timeouts = 0;
}
void
server_input_stdin_data(int type, int plen, void *ctxt)
{
char *data;
u_int data_len;
/* Stdin data from the client. Append it to the buffer. */
/* Ignore any data if the client has closed stdin. */
if (fdin == -1)
return;
data = packet_get_string(&data_len);
packet_integrity_check(plen, (4 + data_len), type);
buffer_append(&stdin_buffer, data, data_len);
memset(data, 0, data_len);
xfree(data);
}
void
server_input_eof(int type, int plen, void *ctxt)
{
/*
* Eof from the client. The stdin descriptor to the
* program will be closed when all buffered data has
* drained.
*/
debug("EOF received for stdin.");
packet_integrity_check(plen, 0, type);
stdin_eof = 1;
}
void
server_input_window_size(int type, int plen, void *ctxt)
{
int row = packet_get_int();
int col = packet_get_int();
int xpixel = packet_get_int();
int ypixel = packet_get_int();
debug("Window change received.");
packet_integrity_check(plen, 4 * 4, type);
if (fdin != -1)
pty_change_window_size(fdin, row, col, xpixel, ypixel);
}
Channel *
server_request_direct_tcpip(char *ctype)
{
int sock, newch;
char *target, *originator;
int target_port, originator_port;
target = packet_get_string(NULL);
target_port = packet_get_int();
originator = packet_get_string(NULL);
originator_port = packet_get_int();
packet_done();
debug("server_request_direct_tcpip: originator %s port %d, target %s port %d",
originator, originator_port, target, target_port);
/* XXX check permission */
sock = channel_connect_to(target, target_port);
xfree(target);
xfree(originator);
if (sock < 0)
return NULL;
newch = channel_new(ctype, SSH_CHANNEL_CONNECTING,
sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT,
CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1);
return (newch >= 0) ? channel_lookup(newch) : NULL;
}
Channel *
server_request_session(char *ctype)
{
int newch;
debug("input_session_request");
packet_done();
/*
* A server session has no fd to read or write until a
* CHANNEL_REQUEST for a shell is made, so we set the type to
* SSH_CHANNEL_LARVAL. Additionally, a callback for handling all
* CHANNEL_REQUEST messages is registered.
*/
newch = channel_new(ctype, SSH_CHANNEL_LARVAL,
-1, -1, -1, 0, CHAN_SES_PACKET_DEFAULT,
0, xstrdup("server-session"), 1);
if (session_open(newch) == 1) {
channel_register_callback(newch, SSH2_MSG_CHANNEL_REQUEST,
session_input_channel_req, (void *)0);
channel_register_cleanup(newch, session_close_by_channel);
return channel_lookup(newch);
} else {
debug("session open failed, free channel %d", newch);
channel_free(newch);
}
return NULL;
}
void
server_input_channel_open(int type, int plen, void *ctxt)
{
Channel *c = NULL;
char *ctype;
u_int len;
int rchan;
int rmaxpack;
int rwindow;
ctype = packet_get_string(&len);
rchan = packet_get_int();
rwindow = packet_get_int();
rmaxpack = packet_get_int();
debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
ctype, rchan, rwindow, rmaxpack);
if (strcmp(ctype, "session") == 0) {
c = server_request_session(ctype);
} else if (strcmp(ctype, "direct-tcpip") == 0) {
c = server_request_direct_tcpip(ctype);
}
if (c != NULL) {
debug("server_input_channel_open: confirm %s", ctype);
c->remote_id = rchan;
c->remote_window = rwindow;
c->remote_maxpacket = rmaxpack;
packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(c->remote_id);
packet_put_int(c->self);
packet_put_int(c->local_window);
packet_put_int(c->local_maxpacket);
packet_send();
} else {
debug("server_input_channel_open: failure %s", ctype);
packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(rchan);
packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
if (!(datafellows & SSH_BUG_OPENFAILURE)) {
packet_put_cstring("bla bla");
packet_put_cstring("");
}
packet_send();
}
xfree(ctype);
}
void
server_input_global_request(int type, int plen, void *ctxt)
{
char *rtype;
int want_reply;
int success = 0;
rtype = packet_get_string(NULL);
want_reply = packet_get_char();
debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
/* -R style forwarding */
if (strcmp(rtype, "tcpip-forward") == 0) {
struct passwd *pw;
char *listen_address;
u_short listen_port;
pw = auth_get_user();
if (pw == NULL)
fatal("server_input_global_request: no user");
listen_address = packet_get_string(NULL); /* XXX currently ignored */
listen_port = (u_short)packet_get_int();
debug("server_input_global_request: tcpip-forward listen %s port %d",
listen_address, listen_port);
/* check permissions */
if (!options.allow_tcp_forwarding ||
no_port_forwarding_flag ||
(listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) {
success = 0;
packet_send_debug("Server has disabled port forwarding.");
} else {
/* Start listening on the port */
success = channel_request_forwarding(
listen_address, listen_port,
/*unspec host_to_connect*/ "<unspec host>",
/*unspec port_to_connect*/ 0,
options.gateway_ports, /*remote*/ 1);
}
xfree(listen_address);
}
if (want_reply) {
packet_start(success ?
SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
packet_send();
packet_write_wait();
}
xfree(rtype);
}
void
server_init_dispatch_20(void)
{
debug("server_init_dispatch_20");
dispatch_init(&dispatch_protocol_error);
dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request);
dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
/* client_alive */
dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure);
/* rekeying */
dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
}
void
server_init_dispatch_13(void)
{
debug("server_init_dispatch_13");
dispatch_init(NULL);
dispatch_set(SSH_CMSG_EOF, &server_input_eof);
dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
}
void
server_init_dispatch_15(void)
{
server_init_dispatch_13();
debug("server_init_dispatch_15");
dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
}
void
server_init_dispatch(void)
{
if (compat20)
server_init_dispatch_20();
else if (compat13)
server_init_dispatch_13();
else
server_init_dispatch_15();
}
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