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77a88811f1963bc5301c20f43c7bd8037f8849c7
libssh/libssh/channels.c
Aris Adamantiadis 77a88811f1 change doxygen doc for channel_poll 
git-svn-id: svn+ssh://svn.berlios.de/svnroot/repos/libssh/trunk@145 7dcaeef0-15fb-0310-b436-a5af3365683c
2008-03-07 03:07:39 +00:00

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/* channels.c */
/* It has support for ... ssh channels */
/*
Copyright 2003 Aris Adamantiadis
This file is part of the SSH Library
The SSH Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The SSH Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the SSH Library; see the file COPYING. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <netdb.h>
#include "libssh/priv.h"
#include "libssh/ssh2.h"
#define WINDOWLIMIT 1024
#define WINDOWBASE 32000
/** defgroup ssh_channel
* \brief functions that manage a channel
*/
/** \addtogroup ssh_channel
* @{ */
/** \brief allocate a new channel
* \param session ssh session
* \return an allocated channel. As this function doesn't speak with server, it never fails
*/
CHANNEL *channel_new(SSH_SESSION *session){
CHANNEL *channel=malloc(sizeof(CHANNEL));
memset(channel,0,sizeof(CHANNEL));
channel->session=session;
channel->version=session->version;
channel->stdout_buffer=buffer_new();
channel->stderr_buffer=buffer_new();
if(!session->channels){
session->channels=channel;
channel->next=channel->prev=channel;
return channel;
}
channel->next=session->channels;
channel->prev=session->channels->prev;
channel->next->prev=channel;
channel->prev->next=channel;
return channel;
}
u32 ssh_channel_new_id(SSH_SESSION *session){
u32 ret=session->maxchannel;
session->maxchannel++;
return ret;
}
static int channel_open(CHANNEL *channel,char *type_c,int window,
int maxpacket,BUFFER *payload){
SSH_SESSION *session=channel->session;
STRING *type=string_from_char(type_c);
u32 foo;
int err;
packet_clear_out(session);
buffer_add_u8(session->out_buffer,SSH2_MSG_CHANNEL_OPEN);
channel->local_channel=ssh_channel_new_id(session);
channel->local_maxpacket=maxpacket;
channel->local_window=window;
ssh_say(2,"creating a channel %d with %d window and %d max packet\n",
channel->local_channel, window,maxpacket);
buffer_add_ssh_string(session->out_buffer,type);
buffer_add_u32(session->out_buffer,htonl(channel->local_channel));
buffer_add_u32(session->out_buffer,htonl(channel->local_window));
buffer_add_u32(session->out_buffer,htonl(channel->local_maxpacket));
free(type);
if(payload)
buffer_add_buffer(session->out_buffer,payload);
packet_send(session);
ssh_say(2,"Sent a SSH_MSG_CHANNEL_OPEN type %s for channel %d\n",type_c,channel->local_channel);
err=packet_wait(session,SSH2_MSG_CHANNEL_OPEN_CONFIRMATION,1);
switch(session->in_packet.type){
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
buffer_get_u32(session->in_buffer,&foo);
if(channel->local_channel!=ntohl(foo)){
ssh_set_error(session,SSH_FATAL,"server answered with sender chan num %d instead of given %d",
ntohl(foo),channel->local_channel);
return -1;
}
buffer_get_u32(session->in_buffer,&foo);
channel->remote_channel=ntohl(foo);
buffer_get_u32(session->in_buffer,&foo);
channel->remote_window=ntohl(foo);
buffer_get_u32(session->in_buffer,&foo);
channel->remote_maxpacket=ntohl(foo);
ssh_say(3,"Received a CHANNEL_OPEN_CONFIRMATION for channel %d:%d\n"
,channel->local_channel,channel->remote_channel);
ssh_say(3,"Remote window : %ld, maxpacket : %ld\n",
channel->remote_window, channel->remote_maxpacket);
channel->open=1;
return 0;
case SSH2_MSG_CHANNEL_OPEN_FAILURE:
{
u32 code;
STRING *error_s;
char *error;
buffer_get_u32(session->in_buffer,&foo);
buffer_get_u32(session->in_buffer,&code);
error_s=buffer_get_ssh_string(session->in_buffer);
error=string_to_char(error_s);
ssh_set_error(session,SSH_REQUEST_DENIED,"Channel opening failure : channel %d error (%d) %s",
channel->local_channel,ntohl(code),error);
free(error);
free(error_s);
return -1;
}
default:
ssh_set_error(session,SSH_FATAL,"Received unknown packet %d\n",session->in_packet.type);
return -1;
}
return -1;
}
CHANNEL *ssh_channel_from_local(SSH_SESSION *session,u32 num){
// we assume we are always the local
CHANNEL *initchan,*channel;
initchan=session->channels;
if(!initchan)
return NULL;
for(channel=initchan;channel->local_channel!=num;channel=channel->next){
if(channel->next==initchan)
return NULL;
}
return channel;
}
static void grow_window(SSH_SESSION *session, CHANNEL *channel){
u32 new_window=WINDOWBASE;
packet_clear_out(session);
buffer_add_u8(session->out_buffer,SSH2_MSG_CHANNEL_WINDOW_ADJUST);
buffer_add_u32(session->out_buffer,htonl(channel->remote_channel));
buffer_add_u32(session->out_buffer,htonl(new_window));
packet_send(session);
ssh_say(3,"growing window (channel %d:%d) to %d bytes\n",
channel->local_channel,channel->remote_channel,
channel->local_window + new_window);
channel->local_window+=new_window;
}
static CHANNEL *channel_from_msg(SSH_SESSION *session){
u32 chan;
CHANNEL *channel;
if (buffer_get_u32(session->in_buffer,&chan)!=sizeof(u32)){
ssh_set_error(session,SSH_FATAL,"Getting channel from message : short read");
return NULL;
}
channel=ssh_channel_from_local(session,ntohl(chan));
if(!channel)
ssh_set_error(session,SSH_FATAL,"Server specified invalid channel %d",ntohl(chan));
return channel;
}
static void channel_rcv_change_window(SSH_SESSION *session){
u32 bytes;
CHANNEL *channel;
int err;
channel=channel_from_msg(session);
if(!channel)
ssh_say(0,"%s\n",ssh_get_error(session));
err = buffer_get_u32(session->in_buffer,&bytes);
if(!channel || err!= sizeof(u32)){
ssh_say(1,"Error getting a window adjust message : invalid packet\n");
return;
}
bytes=ntohl(bytes);
ssh_say(3,"Adding %d bytes to channel (%d:%d) (from %d bytes)\n",bytes,
channel->local_channel,channel->remote_channel,channel->remote_window);
channel->remote_window+=bytes;
}
/* is_stderr is set to 1 if the data are extended, ie stderr */
static void channel_rcv_data(SSH_SESSION *session,int is_stderr){
STRING *str;
CHANNEL *channel;
channel=channel_from_msg(session);
if(!channel){
ssh_say(0,"%s",ssh_get_error(session));
return;
}
if(is_stderr){
u32 ignore;
/* uint32 data type code. we can ignore it */
buffer_get_u32(session->in_buffer,&ignore);
}
str=buffer_get_ssh_string(session->in_buffer);
if(!str){
ssh_say(0,"Invalid data packet !\n");
return;
}
ssh_say(3,"adding %d bytes data in %d\n",string_len(str),is_stderr);
/* what shall we do in this case ? let's accept it anyway */
if(string_len(str)>channel->local_window)
ssh_say(0,"Data packet too big for our window(%d vs %d)",string_len(str),channel->local_window);
channel_default_bufferize(channel,str->string,string_len(str), is_stderr);
if(string_len(str)>=channel->local_window)
channel->local_window-=string_len(str);
else
channel->local_window=0; /* buggy remote */
if(channel->local_window < WINDOWLIMIT)
grow_window(session,channel); /* i wonder if this is the correct place to do that */
free(str);
}
static void channel_rcv_eof(SSH_SESSION *session){
CHANNEL *channel;
channel=channel_from_msg(session);
if(!channel){
ssh_say(0,"%s\n",ssh_get_error(session));
return;
}
ssh_say(2,"Received eof on channel (%d:%d)\n",channel->local_channel,
channel->remote_channel);
// channel->remote_window=0;
channel->remote_eof=1;
}
static void channel_rcv_close(SSH_SESSION *session){
CHANNEL *channel;
channel=channel_from_msg(session);
if(!channel){
ssh_say(0,"%s\n",ssh_get_error(session));
return;
}
ssh_say(2,"Received close on channel (%d:%d)\n",channel->local_channel,
channel->remote_channel);
if((channel->stdout_buffer && buffer_get_rest_len(channel->stdout_buffer)>0)
|| (channel->stderr_buffer && buffer_get_rest_len(channel->stderr_buffer)>0))
channel->delayed_close=1;
else
channel->open=0;
if(!channel->remote_eof)
ssh_say(2,"Remote host not polite enough to send an eof before close\n");
channel->remote_eof=1;
/* the remote eof doesn't break things if there was still data into read
* buffer because the eof is ignored until the buffer is empty. */
}
static void channel_rcv_request(SSH_SESSION *session){
STRING *request_s;
char *request;
u32 status;
CHANNEL *channel=channel_from_msg(session);
if(!channel){
ssh_say(1,"%s\n",ssh_get_error(session));
return;
}
request_s=buffer_get_ssh_string(session->in_buffer);
if(!request_s){
ssh_say(0,"Invalid MSG_CHANNEL_REQUEST\n");
return;
}
buffer_get_u8(session->in_buffer,(u8 *)&status);
request=string_to_char(request_s);
if(!strcmp(request,"exit-status")){
buffer_get_u32(session->in_buffer,&status);
status=ntohl(status);
/* XXX do something with status, we might need it */
free(request_s);
free(request);
return ;
}
if(!strcmp(request,"exit-signal")){
STRING *signal_s;
char *signal;
char *core="(core dumped)";
u8 i;
signal_s=buffer_get_ssh_string(session->in_buffer);
if(!signal_s){
ssh_say(0,"Invalid MSG_CHANNEL_REQUEST\n");
free(request_s);
free(request);
return;
}
signal=string_to_char(signal_s);
buffer_get_u8(session->in_buffer,&i);
if(!i)
core="";
ssh_say(0,"Remote connection closed by signal SIG%s %s\n",signal,core);
free(signal_s);
free(signal);
free(request_s);
free(request);
return;
}
ssh_say(0,"Unknown request %s\n",request);
free(request_s);
free(request);
}
/* channel_handle is called by wait_packet, ie, when there is channel informations to handle . */
void channel_handle(SSH_SESSION *session, int type){
ssh_say(3,"Channel_handle(%d)\n",type);
switch(type){
case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
channel_rcv_change_window(session);
break;
case SSH2_MSG_CHANNEL_DATA:
channel_rcv_data(session,0);
break;
case SSH2_MSG_CHANNEL_EXTENDED_DATA:
channel_rcv_data(session,1);
break;
case SSH2_MSG_CHANNEL_EOF:
channel_rcv_eof(session);
break;
case SSH2_MSG_CHANNEL_CLOSE:
channel_rcv_close(session);
break;
case SSH2_MSG_CHANNEL_REQUEST:
channel_rcv_request(session);
break;
default:
ssh_say(0,"Unexpected message %d\n",type);
}
}
/* when data has been received from the ssh server, it can be applied to the known
user function, with help of the callback, or inserted here */
/* XXX is the window changed ? */
void channel_default_bufferize(CHANNEL *channel, void *data, int len, int is_stderr){
ssh_say(3,"placing %d bytes into channel buffer (stderr=%d)\n",len,is_stderr);
if(!is_stderr){
/* stdout */
if(!channel->stdout_buffer)
channel->stdout_buffer=buffer_new();
buffer_add_data(channel->stdout_buffer,data,len);
} else {
/* stderr */
if(!channel->stderr_buffer)
channel->stderr_buffer=buffer_new();
buffer_add_data(channel->stderr_buffer,data,len);
}
}
/** \brief open a session channel (suited for a shell. Not tcp)
* \param channel an allocated channel (see channel_new())
* \return SSH_OK on success\n
* SSH_ERROR on error
* \see channel_open_forward()
* \see channel_request_env()
* \see channel_request_shell()
* \see channel_request_exec()
* \warning API changed from 0.11
*/
int channel_open_session(CHANNEL *channel){
#ifdef HAVE_SSH1
if(channel->session->version==2)
#endif
return channel_open(channel,"session",64000,32000,NULL);
#ifdef HAVE_SSH1
else
return channel_open_session1(channel);
#endif
}
/** \brief open a TCP/IP forwarding channel.
* \param channel an allocated channel (see channel_new())
* \param remotehost remote host to be connected (host name or IP)
* \param remoteport remote port
* \param sourcehost source host (your local computer). It's facultative and for logging purpose
* \param localport source port (your local computer). It's facultative and for logging purpose
* \return SSH_ERROR on error\n
* SSH_OK on success
* \warning API changed from 0.11
*/
int channel_open_forward(CHANNEL *channel,char *remotehost, int remoteport, char *sourcehost, int localport){
BUFFER *payload=buffer_new();
STRING *str=string_from_char(remotehost);
int ret;
buffer_add_ssh_string(payload,str);
free(str);
str=string_from_char(sourcehost);
buffer_add_u32(payload,htonl(remoteport));
buffer_add_ssh_string(payload,str);
free(str);
buffer_add_u32(payload,htonl(localport));
ret=channel_open(channel,"direct-tcpip",64000,32000,payload);
buffer_free(payload);
return ret;
}
/** \brief close and free a channel
* \param channel channel to free
* \warning any data unread on channel will be lost
*/
void channel_free(CHANNEL *channel){
SSH_SESSION *session=channel->session;
if(session->alive && channel->open)
channel_close(channel);
/* handle the "my channel is first on session list" case */
if(session->channels==channel)
session->channels=channel->next;
/* handle the "my channel is the only on session list" case */
if(channel->next == channel){
session->channels=NULL;
} else {
channel->prev->next=channel->next;
channel->next->prev=channel->prev;
}
if(channel->stdout_buffer)
buffer_free(channel->stdout_buffer);
if(channel->stderr_buffer)
buffer_free(channel->stderr_buffer);
/* debug trick to catch use after frees */
memset(channel,'X',sizeof(CHANNEL));
free(channel);
}
/** it doesn't close the channel. You may still read from it but not write.
* \brief send an end of file on the channel
* \param channel channel
* \return SSH_ERROR on error\n
* SSH_SUCCESS on success
* \see channel_close()
* \see channel_free()
*/
int channel_send_eof(CHANNEL *channel){
SSH_SESSION *session=channel->session;
int ret;
packet_clear_out(session);
buffer_add_u8(session->out_buffer,SSH2_MSG_CHANNEL_EOF);
buffer_add_u32(session->out_buffer,htonl(channel->remote_channel));
ret=packet_send(session);
ssh_say(1,"Sent a EOF on client channel (%d:%d)\n",channel->local_channel,
channel->remote_channel);
channel->local_eof=1;
return ret;
}
/** It sends an end of file and then closes the channel. You won't be able
* to recover any data the server was going to send or was in buffers.
* \brief close a channel
* \param channel channel
* \return SSH_ERROR on error\n
* SSH_SUCCESS on success
* \see channel_free()
* \see channel_eof()
*/
int channel_close(CHANNEL *channel){
SSH_SESSION *session=channel->session;
int ret=0;
if(!channel->local_eof)
ret=channel_send_eof(channel);
if(ret)
return ret;
packet_clear_out(session);
buffer_add_u8(session->out_buffer,SSH2_MSG_CHANNEL_CLOSE);
buffer_add_u32(session->out_buffer,htonl(channel->remote_channel));
ret=packet_send(session);
ssh_say(1,"Sent a close on client channel (%d:%d)\n",channel->local_channel,
channel->remote_channel);
if(!ret)
channel->open =0;
return ret;
}
/** \brief blocking write on channel
* \param channel channel
* \param data pointer to data to write
* \param len length of data
* \return number of bytes written on success\n
* SSH_ERROR on error
* \see channel_read()
*/
int channel_write(CHANNEL *channel ,void *data,int len){
SSH_SESSION *session=channel->session;
int effectivelen;
int origlen=len;
if(channel->local_eof){
ssh_set_error(session,SSH_REQUEST_DENIED,"Can't write to channel %d:%d"
" after EOF was sent",channel->local_channel,channel->remote_channel);
return -1;
}
if(!channel->open || channel->delayed_close){
ssh_set_error(session,SSH_REQUEST_DENIED,"Remote channel is closed");
return -1;
}
#ifdef HAVE_SSH1
if(channel->version==1)
return channel_write1(channel,data,len);
#endif
while(len >0){
if(channel->remote_window<len){
ssh_say(2,"Remote window is %d bytes. going to write %d bytes\n",
channel->remote_window,len);
ssh_say(2,"Waiting for a growing window message...\n");
// wonder what happens when the channel window is zero
while(channel->remote_window==0){
// parse every incoming packet
packet_wait(channel->session,0,0);
}
effectivelen=len>channel->remote_window?channel->remote_window:len;
} else
effectivelen=len;
packet_clear_out(session);
buffer_add_u8(session->out_buffer,SSH2_MSG_CHANNEL_DATA);
buffer_add_u32(session->out_buffer,htonl(channel->remote_channel));
buffer_add_u32(session->out_buffer,htonl(effectivelen));
buffer_add_data(session->out_buffer,data,effectivelen);
packet_send(session);
ssh_say(2,"channel_write wrote %d bytes\n",effectivelen);
channel->remote_window-=effectivelen;
len -= effectivelen;
data+=effectivelen;
}
return origlen;
}
/** \brief returns if the channel is open or not
* \param channel channel
* \return 0 if channel is closed, nonzero otherwise
* \see channel_is_closed()
*/
int channel_is_open(CHANNEL *channel){
return (channel->open!=0 && channel->session->alive);
}
/** \brief returns if the channel is closed or not
* \param channel channel
* \return 0 if channel is opened, nonzero otherwise
* \see channel_is_open()
*/
int channel_is_closed(CHANNEL *channel){
return (channel->open==0 || !channel->session->alive);
}
/** \brief returns if the remote has sent an EOF
* \param channel channel
* \return 0 if there is no EOF, nonzero otherwise
*/
int channel_is_eof(CHANNEL *channel){
if((channel->stdout_buffer && buffer_get_rest_len(channel->stdout_buffer)
>0) || (channel->stderr_buffer && buffer_get_rest_len(
channel->stderr_buffer)>0))
return 0;
return (channel->remote_eof!=0);
}
/** \brief put the channel into nonblocking mode
* \param channel channel
* \param blocking boolean for blocking or nonblocking
* \bug This functionnality is still under development and
* doesn't work correctly
*/
void channel_set_blocking(CHANNEL *channel, int blocking){
channel->blocking=blocking;
}
static int channel_request(CHANNEL *channel,char *request, BUFFER *buffer,int reply){
STRING *request_s=string_from_char(request);
SSH_SESSION *session=channel->session;
int err;
packet_clear_out(session);
buffer_add_u8(session->out_buffer,SSH2_MSG_CHANNEL_REQUEST);
buffer_add_u32(session->out_buffer,htonl(channel->remote_channel));
buffer_add_ssh_string(session->out_buffer,request_s);
buffer_add_u8(session->out_buffer,reply?1:0);
if(buffer)
buffer_add_data(session->out_buffer,buffer_get(buffer),buffer_get_len(buffer));
packet_send(session);
ssh_say(3,"Sent a SSH_MSG_CHANNEL_REQUEST %s\n",request);
free(request_s);
if(!reply)
return 0;
err=packet_wait(session,SSH2_MSG_CHANNEL_SUCCESS,1);
if(err)
if(session->in_packet.type==SSH2_MSG_CHANNEL_FAILURE){
ssh_say(2,"%s channel request failed\n",request);
ssh_set_error(session,SSH_REQUEST_DENIED,"Channel request %s failed",request);
}
else
ssh_say(3,"Received an unexpected %d message\n",session->in_packet.type);
else
ssh_say(3,"Received a SUCCESS\n");
return err;
}
/** \brief requests a pty with a specific type and size
* \param channel channel
* \param terminal terminal type ("vt100, xterm,...")
* \param col number of cols
* \param row number of rows
* \return SSH_SUCCESS on success\n
* SSH_ERROR on error
*/
int channel_request_pty_size(CHANNEL *channel, char *terminal, int col, int row){
STRING *term;
BUFFER *buffer;
int err;
#ifdef HAVE_SSH1
if(channel->version==1)
return channel_request_pty_size1(channel,terminal, col, row);
#endif
term=string_from_char(terminal);
buffer=buffer_new();
buffer_add_ssh_string(buffer,term);
buffer_add_u32(buffer,htonl(col));
buffer_add_u32(buffer,htonl(row));
buffer_add_u32(buffer,0);
buffer_add_u32(buffer,0);
/* a 0byte string */
buffer_add_u32(buffer,htonl(1));
buffer_add_u8(buffer,0);
free(term);
err=channel_request(channel,"pty-req",buffer,1);
buffer_free(buffer);
return err;
}
/** \brief requests a pty
* \param channel channel
* \see channel_request_pty_size()
* \return SSH_SUCCESS on success\n
* SSH_ERROR on error
*/
int channel_request_pty(CHANNEL *channel){
return channel_request_pty_size(channel,"xterm",80,24);
}
/** \brief change the size of the terminal associated to a channel
* \param channel channel
* \param cols new number of cols
* \param rows new number of rows
* \warning Do not call it from a signal handler if you are not
* sure any other libssh function using the same channel/session
* is running at same time (not 100% threadsafe)
*/
int channel_change_pty_size(CHANNEL *channel,int cols,int rows){
BUFFER *buffer;
int err;
#ifdef HAVE_SSH1
if(channel->version==1)
return channel_change_pty_size1(channel,cols,rows);
#endif
buffer=buffer_new();
//buffer_add_u8(buffer,0);
buffer_add_u32(buffer,htonl(cols));
buffer_add_u32(buffer,htonl(rows));
buffer_add_u32(buffer,0);
buffer_add_u32(buffer,0);
err=channel_request(channel,"window-change",buffer,0);
buffer_free(buffer);
return err;
}
/** \brief requests a shell
* \param channel
* \returns SSH_SUCCESS on success\n
* SSH_ERROR on error
*/
int channel_request_shell(CHANNEL *channel){
#ifdef HAVE_SSH1
if(channel->version==1)
return channel_request_shell1(channel);
#endif
return channel_request(channel,"shell",NULL,1);
}
/** \brief requests a subsystem (for example sftp)
* \param channel channel
* \param system subsystem to request (for example sftp)
* \return SSH_SUCCESS on success\n
* SSH_ERROR on error
* \warning you normally don't have to call it to have sftp
* \see sftp_new()
*/
int channel_request_subsystem(CHANNEL *channel, char *system){
BUFFER* buffer=buffer_new();
int ret;
STRING *subsystem=string_from_char(system);
buffer_add_ssh_string(buffer,subsystem);
free(subsystem);
ret=channel_request(channel,"subsystem",buffer,1);
buffer_free(buffer);
return ret;
}
int channel_request_sftp( CHANNEL *channel){
return channel_request_subsystem(channel, "sftp");
}
/** \brief set the environement variables
* \param channel channel
* \param name name of the variable
* \param value value
* \return SSH_SUCCESS on success\n
* SSH_ERROR on error
* \warning some environement variables may be refused by security
* */
int channel_request_env(CHANNEL *channel,char *name, char *value){
BUFFER *buffer=buffer_new();
int ret;
STRING *string=string_from_char(name);
buffer_add_ssh_string(buffer,string);
free(string);
string=string_from_char(value);
buffer_add_ssh_string(buffer,string);
free(string);
ret=channel_request(channel,"env",buffer,1);
buffer_free(buffer);
return ret;
}
/** it's similar to sh -c "command"
* \brief run a shell command without an interactive shell
* \param channel channel
* \param cmd command to execute (by ex. "ls ~/ -al | grep -i reports")
* \return SSH_SUCCESS on success\n
* SSH_ERROR on error
* \see channel_request_shell()
*/
int channel_request_exec(CHANNEL *channel, char *cmd){
BUFFER *buffer;
int ret;
#ifdef HAVE_SSH1
if(channel->version==1)
return channel_request_exec1(channel, cmd);
#endif
buffer=buffer_new();
STRING *command=string_from_char(cmd);
buffer_add_ssh_string(buffer,command);
free(command);
ret=channel_request(channel,"exec",buffer,1);
buffer_free(buffer);
return ret;
}
/* TODO : fix the delayed close thing */
/* TODO : fix the blocking behaviours */
/* reads into a channel and put result into buffer */
/* returns number of bytes read, 0 if eof or such and -1 in case of error */
/* if bytes != 0, the exact number of bytes are going to be read */
/** \brief reads data from a channel
* \param channel channel
* \param buffer buffer which will get the data
* \param bytes number of bytes to be read. If it is bigger
* than 0, the exact size will be read, else (bytes=0) it will return
* once anything is available
* \param is_stderr boolean value to mark reading from the stderr flow.
* \return number of bytes read\n
* 0 on end of file\n
* SSH_ERROR on error
*/
int channel_read(CHANNEL *channel, BUFFER *buffer,int bytes,int is_stderr){
BUFFER *stdbuf=NULL;
int len;
buffer_reinit(buffer);
/* maybe i should always set a buffer to avoid races between channel_default_bufferize and channel_read */
if(is_stderr)
stdbuf=channel->stderr_buffer;
else
stdbuf=channel->stdout_buffer;
/* block reading if asked bytes=0 */
while((buffer_get_rest_len(stdbuf)==0) || (buffer_get_rest_len(stdbuf) < bytes)){
if(channel->remote_eof && buffer_get_rest_len(stdbuf)==0)
return 0;
if(channel->remote_eof)
break; /* return the resting bytes in buffer */
if(packet_read(channel->session)||packet_translate(channel->session))
return -1;
packet_parse(channel->session);
}
if(bytes==0){
/* write the ful buffer informations */
buffer_add_data(buffer,buffer_get_rest(stdbuf),buffer_get_rest_len(stdbuf));
buffer_reinit(stdbuf);
} else {
len=buffer_get_rest_len(stdbuf);
len= (len>bytes?bytes:len); /* read bytes bytes if len is greater, everything otherwise */
buffer_add_data(buffer,buffer_get_rest(stdbuf),len);
buffer_pass_bytes(stdbuf,len);
}
return buffer_get_len(buffer);
}
/** \brief polls the channel for data to read
* \param channel channel
* \param is_stderr boolean to select the stderr stream
* \return number of bytes available for reading\n
* 0 if nothing is available\n
* SSH_ERROR on error
* \warning When the channel is in EOF state, the function returns 1
* \see channel_is_eof()
*/
int channel_poll(CHANNEL *channel, int is_stderr){
BUFFER *buffer;
int r=0;
if(is_stderr)
buffer=channel->stderr_buffer;
else
buffer=channel->stdout_buffer;
while(buffer_get_rest_len(buffer)==0 && !channel->remote_eof){
r=ssh_handle_packets(channel->session);
if(r<=0)
return r;
}
if(channel->remote_eof)
return 1;
return buffer_get_rest_len(buffer);
}
/* nonblocking read on the specified channel. it will return <=len bytes of data read
atomicly. */
/** This read will make a nonblocking read (unlike channel_read()) and won't force you
* to deal with BUFFER's
* \brief nonblocking read
* \param channel channel
* \param dest pointer to destination for data
* \param len maximum length of data to be read
* \param is_stderr boolean to select the stderr stream
* \return number of bytes read\n
* 0 if nothing is available\n
* SSH_ERROR on error
* \warning don't forget to check for EOF as it would
* return 0 here
* \see channel_is_eof()
*/
int channel_read_nonblocking(CHANNEL *channel, char *dest, int len, int is_stderr){
int to_read=channel_poll(channel,is_stderr);
int lu;
BUFFER *buffer=buffer_new();
if(to_read<=0){
buffer_free(buffer);
return to_read; /* may be an error code */
}
if(to_read>len)
to_read=len;
lu=channel_read(channel,buffer,to_read,is_stderr);
memcpy(dest,buffer_get(buffer),lu>=0?lu:0);
buffer_free(buffer);
return lu;
}
/** \brief recover the session in which belong a channel
* \param channel channel
* \return the session pointer
*/
SSH_SESSION *channel_get_session(CHANNEL *channel){
return channel->session;
}
/* This function acts as a meta select. */
/* first, channels are analyzed to seek potential can-write or can-read ones. */
/* Then, if no channel has been elected, it goes in a loop with the posix select(2) */
/* this is made in two parts : Protocol select and Network select */
/* the protocol select does not use the network functions at all */
static int channel_protocol_select(CHANNEL **rchans, CHANNEL **wchans, CHANNEL **echans,
CHANNEL **rout, CHANNEL **wout, CHANNEL **eout){
CHANNEL *chan;
int i,j;
j=0;
for(i=0;rchans[i];++i){
chan=rchans[i];
while(chan->open && chan->session->data_to_read){
ssh_handle_packets(chan->session);
}
if( (chan->stdout_buffer && buffer_get_len(chan->stdout_buffer)>0) ||
(chan->stderr_buffer && buffer_get_len(chan->stderr_buffer)>0) ||
chan->remote_eof){
rout[j]=chan;
++j;
}
}
rout[j]=NULL;
j=0;
for(i=0;wchans[i];++i){
chan=wchans[i];
/* it's not our business to seek if the file descriptor is writable */
if(chan->session->data_to_write && chan->open && (chan->remote_window>0)){
wout[j]=chan;
++j;
}
}
wout[j]=NULL;
j=0;
for(i=0;echans[i];++i){
chan=echans[i];
if(!ssh_socket_is_open(chan->session->socket) || !chan->open || chan->session->data_except){
eout[j]=chan;
++j;
}
}
eout[j]=NULL;
return 0;
}
/* just count number of pointers in the array */
static int count_ptrs(CHANNEL **ptrs){
int c;
for(c=0;ptrs[c];++c)
;
return c;
}
/** the list of pointers are then actualized and will only contain pointers to
* channels that are respectively readable, writable or have an exception to trap
* \brief act as the standard select(2) for channels
* \param readchans a NULL pointer or an array of channel pointers, finished by a NULL
* \param writechans a NULL pointer or an array of channel pointers, finished by a NULL
* \param exceptchans a NULL pointer or an array of channel pointers, finished by a NULL
* \param timeout timeout as defined by select(2)
* \return SSH_SUCCESS operation successful\n
* SSH_EINTR select(2) syscall was interrupted, relaunch the function
*/
int channel_select(CHANNEL **readchans, CHANNEL **writechans, CHANNEL **exceptchans, struct
timeval * timeout){
fd_set rset;
fd_set wset;
fd_set eset;
CHANNEL *dummy=NULL;
CHANNEL **rchans, **wchans, **echans;
int fdmax=-1;
int i;
int r;
/* don't allow NULL pointers */
if(!readchans)
readchans=&dummy;
if(!writechans)
writechans=&dummy;
if(!exceptchans)
exceptchans=&dummy;
if(!readchans[0] && !writechans[0] && !exceptchans[0]){
/* no channel to poll ?? go away ! */
return 0;
}
/* prepare the outgoing temporary arrays */
rchans=malloc(sizeof(CHANNEL *) * (count_ptrs(readchans)+1));
wchans=malloc(sizeof(CHANNEL *) * (count_ptrs(writechans)+1));
echans=malloc(sizeof(CHANNEL *) * (count_ptrs(exceptchans)+1));
/* first, try without doing network stuff */
/* then, select and redo the networkless stuff */
do {
channel_protocol_select(readchans,writechans,exceptchans,rchans,wchans,echans);
if(rchans[0]||wchans[0]||echans[0]){
/* we've got one without doing any select */
/* overwrite the begining arrays */
memcpy(readchans,rchans, (count_ptrs(rchans)+1)*sizeof(CHANNEL *));
memcpy(writechans,wchans, (count_ptrs(wchans)+1)*sizeof(CHANNEL *));
memcpy(exceptchans,echans, (count_ptrs(echans)+1)*sizeof(CHANNEL *));
free(rchans);
free(wchans);
free(echans);
return 0;
}
ssh_say(3,"doing a select for the different channels\n");
/* since we verified the invalid fd cases into the networkless select,
we can be sure all fd are valid ones */
FD_ZERO(&rset);
FD_ZERO(&wset);
FD_ZERO(&eset);
for(i=0;readchans[i];++i){
if(!ssh_socket_fd_isset(readchans[i]->session->socket,&rset))
ssh_socket_fd_set(readchans[i]->session->socket, &rset, &fdmax);
}
for(i=0;writechans[i];++i){
if(!ssh_socket_fd_isset(writechans[i]->session->socket,&wset))
ssh_socket_fd_set(writechans[i]->session->socket,&wset, &fdmax);
}
for(i=0;exceptchans[i];++i){
if(!ssh_socket_fd_isset(exceptchans[i]->session->socket,&eset))
ssh_socket_fd_set(exceptchans[i]->session->socket,&eset,&fdmax);
}
/* fd=readchans[i]->session->fd;
if(!FD_ISSET(fd,&rset)){
FD_SET(fd,&rset);
if(fd>=fdmax)
fdmax=fd+1;
}
}
for(i=0;writechans[i];++i){
fd=writechans[i]->session->fd;
if(!FD_ISSET(fd,&wset)){
FD_SET(fd,&wset);
if(fd>=fdmax)
fdmax=fd+1;
}
}
for(i=0;exceptchans[i];++i){
fd=exceptchans[i]->session->fd;
if(!FD_ISSET(fd,&eset)){
FD_SET(fd,&eset);
if(fd>=fdmax)
fdmax=fd+1;
}
}
*/
/* here we go */
r=select(fdmax,&rset,&wset,&eset,timeout);
/* leave if select was interrupted */
if(r==EINTR){
free(rchans);
free(wchans);
free(echans);
return SSH_EINTR;
}
for(i=0;readchans[i];++i){
if(ssh_socket_fd_isset(readchans[i]->session->socket,&rset))
readchans[i]->session->data_to_read=1;
}
for(i=0;writechans[i];++i){
if(ssh_socket_fd_isset(writechans[i]->session->socket,&wset))
writechans[i]->session->data_to_write=1;
}
for(i=0;exceptchans[i];++i){
if(ssh_socket_fd_isset(exceptchans[i]->session->socket,&eset))
exceptchans[i]->session->data_except=1;
}
} while(1); /* return to do loop */
/* not reached */
return 0;
}
/** @} */
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