ssh 0.1.4

//! Bindings to libssh. Unrelated to libssh2 (which also has rust bindings, see the "ssh2" crate),
//!
//! Libssh is a client and server library supporting both versions 1 and 2 of the SSH protocol. The client part follows the behavior of openssh closely, in particular it parses ~/.ssh/config, and accepts ProxyCommand directives automatically.
//!
//! Although this binding is Apache/MIT-licensed, libssl itself is released under the LGPL. Make sure you understand what it means if you plan to link statically (this crate links dynamically by default).
//!
//!# Client examples
//!
//! ```
//! use ssh::*;
//!
//! let mut session=Session::new().unwrap();
//! session.set_host("pijul.org").unwrap();
//! session.parse_config(None).unwrap();
//! session.connect().unwrap();
//! println!("{:?}",session.is_server_known());
//! session.userauth_publickey_auto(None).unwrap();
//! ```
//!
//!## Running a command on a remote server
//!
//!```
//! use ssh::*;
//! use std::io::Read;
//!
//! let mut session=Session::new().unwrap();
//! session.set_host("pijul.org").unwrap();
//! session.parse_config(None).unwrap();
//! session.connect().unwrap();
//! println!("{:?}",session.is_server_known());
//! session.userauth_publickey_auto(None).unwrap();
//! {
//!     let mut s=session.channel_new().unwrap();
//!     s.open_session().unwrap();
//!     s.request_exec(b"ls -l").unwrap();
//!     s.send_eof().unwrap();
//!     let mut buf=Vec::new();
//!     s.stdout().read_to_end(&mut buf).unwrap();
//!     println!("{:?}",std::str::from_utf8(&buf).unwrap());
//! }
//!```
//!
//!## Creating a remote file
//!
//!```
//! use ssh::*;
//! use std::io::Write;
//!
//! let mut session=Session::new().unwrap();
//! session.set_host("pijul.org").unwrap();
//! session.parse_config(None).unwrap();
//! session.connect().unwrap();
//! println!("{:?}",session.is_server_known());
//! session.userauth_publickey_auto(None).unwrap();
//! {
//!     let mut scp=session.scp_new(WRITE,"/tmp").unwrap();
//!     scp.init().unwrap();
//!     let buf=b"blabla blibli\n".to_vec();
//!     scp.push_file("blublu",buf.len(),0o644).unwrap();
//!     scp.write(&buf).unwrap();
//! }
//!```
//!
//!## Creating a remote directory with a file inside
//!
//!```
//! use ssh::*;
//! use std::io::Write;
//!
//! let mut session=Session::new().unwrap();
//! session.set_host("pijul.org").unwrap();
//! session.parse_config(None).unwrap();
//! session.connect().unwrap();
//! println!("{:?}",session.is_server_known());
//! session.userauth_publickey_auto(None).unwrap();
//! {
//!     let mut scp=session.scp_new(RECURSIVE|WRITE,"/tmp").unwrap();
//!     scp.init().unwrap();
//!     scp.push_directory("testdir",0o755).unwrap();
//!     let buf=b"blabla\n".to_vec();
//!     scp.push_file("test file",buf.len(),0o644).unwrap();
//!     scp.write(&buf).unwrap();
//! }
//!
//!```
//!
//!## Reading a remote file
//!
//!```
//! use ssh::*;
//! use std::io::Read;
//!
//! let mut session=Session::new().unwrap();
//! session.set_host("pijul.org").unwrap();
//! session.parse_config(None).unwrap();
//! session.connect().unwrap();
//! println!("{:?}",session.is_server_known());
//! session.userauth_publickey_auto(None).unwrap();
//! {
//!     let mut scp=session.scp_new(READ,"/tmp/blublu").unwrap();
//!     scp.init().unwrap();
//!     loop {
//!         match scp.pull_request().unwrap() {
//!             Request::NEWFILE=>{
//!                 let mut buf:Vec<u8>=vec!();
//!                 scp.accept_request().unwrap();
//!                 scp.reader().read_to_end(&mut buf).unwrap();
//!                 println!("{:?}",std::str::from_utf8(&buf).unwrap());
//!                 break;
//!             },
//!             Request::WARNING=>{
//!                 scp.deny_request().unwrap();
//!                 break;
//!             },
//!             _=>scp.deny_request().unwrap()
//!         }
//!     }
//! }
//!```

extern crate libc;
use self::libc::{c_int,c_uint,c_void,c_char,size_t,uint64_t};
use std::path::Path;
use std::ffi::CString;
use std::io::{Read,Write};
use std::fmt;
use std::ptr::copy_nonoverlapping;
#[macro_use]
extern crate log;

#[macro_use]
extern crate bitflags;

#[allow(missing_copy_implementations)]
enum Session_ {}

#[link(name = "ssh")]
extern "C" {
    fn ssh_new() -> *mut Session_;
    fn ssh_free(s:*mut Session_);
    fn ssh_connect(s:*mut Session_)->c_int;
    fn ssh_disconnect(s:*mut Session_)->c_int;
    fn ssh_options_set(s:*mut Session_,t:c_int,v:*const c_void)->c_int;
    fn ssh_options_parse_config(s:*mut Session_,v:*const c_char)->c_int;
    fn ssh_get_error(s:*const c_void)->*const c_char;
    fn ssh_userauth_password(s:*mut Session_,user:*const c_char,p:*const c_char)->c_int;
    fn ssh_userauth_kbdint(s:*mut Session_,user:*const c_char,p:*const c_char)->c_int;
    fn ssh_userauth_publickey_auto(s:*mut Session_,user:*const c_char,p:*const c_char)->c_int;
    fn ssh_is_server_known(s:*mut Session_)->c_int;
    fn ssh_write_knownhost(s:*mut Session_)->c_int;
    fn ssh_get_pubkey_hash(s:*mut Session_,h:*mut *mut u8)->c_int;
    fn ssh_clean_pubkey_hash(h:*mut *mut u8);
}


pub struct Session {
    session:*mut Session_
}
impl std::fmt::Debug for Session {
    fn fmt(&self,f:&mut std::fmt::Formatter)->Result<(),std::fmt::Error> {
        write!(f,"Session{{..}}")
    }
}

#[allow(dead_code)]
#[repr(C)]
enum SshOptions {
  HOST,
  PORT,
  PORT_STR,
  FD,
  USER,
  SSH_DIR,
  IDENTITY,
  ADD_IDENTITY,
  KNOWNHOSTS,
  TIMEOUT,
  TIMEOUT_USEC,
  SSH1,
  SSH2,
  LOG_VERBOSITY,
  LOG_VERBOSITY_STR,
  CIPHERS_C_S,
  CIPHERS_S_C,
  COMPRESSION_C_S,
  COMPRESSION_S_C,
  PROXYCOMMAND,
  BINDADDR,
  STRICTHOSTKEYCHECK,
  COMPRESSION,
  COMPRESSION_LEVEL,
  KEY_EXCHANGE,
  HOSTKEYS,
  GSSAPI_SERVER_IDENTITY,
  GSSAPI_CLIENT_IDENTITY,
  GSSAPI_DELEGATE_CREDENTIALS,
}

fn path_as_ptr(p:&Path)->CString {
    let p=p.to_str().unwrap();
    std::ffi::CString::new(p).unwrap()
}

#[derive(Debug)]
pub enum Error {
    Ssh(String),
    IO(std::io::Error)
}

fn err(session:&Session)->Error {
    Error::Ssh(unsafe {
        let err=ssh_get_error(session.session as *const c_void);
        let slice=std::slice::from_raw_parts(err as *const u8,libc::strlen(err));
        std::str::from_utf8(slice).unwrap().to_string()
    })
}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            Error::Ssh(ref descr) => write!(f, "SSH error: {}", descr),
            Error::IO(ref e)=> e.fmt(f)
        }
    }
}

//pub type Error=&'static str;
impl std::error::Error for Error {
    fn description(&self) -> &str {
        match *self {
            Error::Ssh(ref descr)=>descr,
            Error::IO(ref e)=>e.description()
        }
    }
    fn cause(&self) -> Option<&std::error::Error> {
        match *self {
            Error::Ssh(_)=>None,
            Error::IO(ref e)=>Some(e)
        }
    }
}
const SSH_OK:c_int=0;

impl From<std::io::Error> for Error {
    fn from(err: std::io::Error) -> Error {
        Error::IO(err)
    }
}

impl Session {
    pub fn new()->Result<Session,()> {
        let session= unsafe {ssh_new()};
        if session.is_null() {
            Err(())
        } else {
            Ok(Session { session:session })
        }
    }
    pub fn set_host(&mut self,v:&str)->Result<(),Error> {
        let v=std::ffi::CString::new(v).unwrap();
        let e = unsafe { ssh_options_set(self.session,SshOptions::HOST as c_int,v.as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self)) }
    }
    pub fn set_port(&mut self,v:usize)->Result<(),Error> {
        let v=[v as c_uint];
        let e = unsafe { ssh_options_set(self.session,SshOptions::PORT as c_int,v.as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    pub fn set_username(&mut self,v:&str)->Result<(),Error> {
        let v=std::ffi::CString::new(v).unwrap();
        let e = unsafe { ssh_options_set(self.session,SshOptions::USER as c_int,v.as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Set the location of the ".ssh" directory, where the config file and keys can be found (it may include "%s", which will be replaced by the user home directory).
    pub fn set_ssh_dir<P: AsRef<Path>>(&mut self,v:P)->Result<(),Error> {
        let e = unsafe { ssh_options_set(self.session,SshOptions::USER as c_int, path_as_ptr(v.as_ref()).as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Set the location of the "knownhosts" file (it may include "%s", which will be replaced by the user home directory).
    pub fn set_knownhosts<P: AsRef<Path>>(&mut self,v:P)->Result<(),Error> {
        let e = unsafe { ssh_options_set(self.session,SshOptions::KNOWNHOSTS as c_int, path_as_ptr(v.as_ref()).as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Set the location of the key to be used for authentication (it may include "%s", which will be replaced by the user home directory).
    pub fn set_identity<P: AsRef<Path>>(&mut self,v:P)->Result<(),Error> {
        let e = unsafe { ssh_options_set(self.session,SshOptions::IDENTITY as c_int, path_as_ptr(v.as_ref()).as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self)) }
    }
    /// Allow version 1 of the protocol (default unspecified).
    pub fn set_ssh1(&mut self,v:bool)->Result<(),Error> {
        let v:[c_int;1]=[if v { 1 } else { 0 }];
        let e = unsafe { ssh_options_set(self.session,SshOptions::SSH1 as c_int, v.as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Allow version 1 of the protocol (default unspecified).
    pub fn set_ssh2(&mut self,v:bool)->Result<(),Error> {
        let v:[c_int;1]=[if v { 1 } else { 0 }];
        let e = unsafe { ssh_options_set(self.session,SshOptions::SSH2 as c_int, v.as_ptr() as *const c_void) };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Parse configuration file. If the path is `None`, then `~/.ssh/config` is read.
    pub fn parse_config(&mut self,path:Option<&Path>)->Result<(),Error> {
        let e=unsafe {
            ssh_options_parse_config(self.session,
                                     match path { Some(p) => path_as_ptr(p).as_ptr() as *const c_char,
                                                  None => std::ptr::null_mut() })
        };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }

    /// Check whether the remote server's key is known.
    pub fn is_server_known(&mut self)->Result<ServerKnown,Error>{
        let e=unsafe {
            ssh_is_server_known(self.session)
        };
        if e>=0 { Ok(unsafe { std::mem::transmute(e) }) }
        else { Err(err(self))}
    }
    /// Accept the remote server's key.
    pub fn write_knownhost(&mut self)->Result<(),Error>{
        let e=unsafe {
            ssh_write_knownhost(self.session)
        };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Get a hash of the server's public key
    pub fn get_pubkey_hash(&mut self)->Result<Vec<u8>,Error>{
        let mut ptr=std::ptr::null_mut();
        let e=unsafe {
            ssh_get_pubkey_hash(self.session,std::mem::transmute(&mut ptr))
        };
        if e>=0 {
            let mut v=vec![0;e as usize];
            unsafe {
                copy_nonoverlapping(ptr, v.as_mut_ptr(), e as usize);
                ssh_clean_pubkey_hash(std::mem::transmute(&mut ptr))
            }
            Ok(v)
        } else {
            unsafe {
                ssh_clean_pubkey_hash(std::mem::transmute(&mut ptr))
            }
            Err(err(self))
        }
    }
    pub fn connect(&mut self)->Result<(),Error>{
        let e=unsafe {
            ssh_connect(self.session)
        };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self))}
    }
    /// Disconnect the session. The session can be reused later to open a new session.
    pub fn disconnect(&mut self)->Result<(),Error>{
        let e=unsafe {ssh_disconnect(self.session)};
        if e==SSH_OK { Ok(()) } else {Err(err(self))}
    }
    /// Authenticate with a password.
    pub fn userauth_password(&mut self,p:&str)->Result<(),Error> {
        let p=std::ffi::CString::new(p).unwrap();
        let e = unsafe {ssh_userauth_password(self.session,std::ptr::null_mut(),p.as_ptr() as *const _)};
        if e==SSH_OK { Ok(()) }
        else { Err(err(self)) }
    }
    /// Print a prompt on the standard output, and then ask the user a password on the standard input. The typed password is not echoed.
    pub fn userauth_kbdint(&mut self,user:Option<&str>)->Result<(),Error> {
        let e = match user {
            None=>unsafe { ssh_userauth_kbdint(self.session,std::ptr::null_mut(),std::ptr::null_mut()) },
            Some(p)=> {
                let p=std::ffi::CString::new(p).unwrap();
                unsafe {ssh_userauth_kbdint(self.session,p.as_ptr() as *const _,std::ptr::null_mut())}
            }
        };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self)) }
    }
    /// Print a prompt on the standard output, and then ask the user a password on the standard input. The typed password is not echoed.
    pub fn userauth_publickey_auto(&mut self,p:Option<&str>)->Result<(),Error> {
        let e = match p {
            None=>{
                unsafe {
                    ssh_userauth_publickey_auto(self.session,
                                                std::ptr::null_mut(),
                                                std::ptr::null_mut())
                }
            },
            Some(p)=> {
                let p=std::ffi::CString::new(p).unwrap();
                unsafe {ssh_userauth_publickey_auto(self.session,
                                                    std::ptr::null_mut(),
                                                    p.as_ptr() as *const _) }
            }
        };
        if e==SSH_OK { Ok(()) }
        else { Err(err(self)) }
    }
    /// Start an SCP connection.
    pub fn scp_new<'b,P: AsRef<Path>>(&'b mut self,mode:Mode,v:P)->Result<Scp<'b>,Error> {
        let scp= unsafe {
            ssh_scp_new(self.session,
                        mode.bits(),
                        path_as_ptr(v.as_ref()).as_ptr() as *const _)
        };
        if scp.is_null() {
            Err(err(self))
        } else {
            Ok(Scp { session:self,
                     scp:scp,size:0 })
        }
    }
    /// Start a channel to issue remote commands.
    pub fn channel_new<'b>(&'b mut self)->Result<Channel<'b>,Error> {
        let e=unsafe { ssh_channel_new(self.session) };
        if e.is_null() {
            Err(err(self))
        } else {
            Ok(Channel { session:self,channel:e })
        }
    }
}


impl Drop for Session {
    fn drop(&mut self) {
        debug!("ssh_free");
        unsafe {ssh_free(self.session)}
    }
}

#[derive(Debug)]
#[repr(C)]
pub enum ServerKnown {
    /// The key is unknown
    NotKnown=0,
    /// The key is known
    Known,
    /// The key has changed since the last connection. You have to warn the user about a possible attack.
    Changed,
    /// The type of the key has changed. Possible attack.
    FoundOther,
    /// The known hosts file doesn't exist, and will be created when `write_knownhost` is called.
    FileNotFound
}

impl ServerKnown {
    pub fn is_known(&self)->bool {
        match *self {
            ServerKnown::Known=>true,
            _=>false
        }
    }
}

#[allow(missing_copy_implementations)]
enum Channel_ {}


extern "C" {
    fn ssh_channel_new(s:*mut Session_)->*mut Channel_;
    fn ssh_channel_close(s:*mut Channel_)->c_int;
    fn ssh_channel_free(s:*mut Channel_);
    fn ssh_channel_open_session(s:*mut Channel_)->c_int;
    fn ssh_channel_request_exec(s:*mut Channel_,b:*const c_char)->c_int;
    fn ssh_channel_read(s:*mut Channel_,b:*mut c_char,c:size_t,is_stderr:c_int)->c_int;
    fn ssh_channel_send_eof(s:*mut Channel_)->c_int;
    fn ssh_channel_get_exit_status(s:*const Channel_)->c_int;
}

pub struct Channel<'b> {
    session:&'b Session,
    channel:*mut Channel_
}

impl <'b> Channel<'b> {
    pub fn open_session(&mut self)->Result<(),Error> {
        let e= unsafe { ssh_channel_open_session(self.channel) };
        if e==0 {
            Ok(())
        } else {
            Err(err(self.session))
        }
    }
}

pub struct ChannelReader<'d,'c:'d> {
    channel:&'d Channel<'c>,
    is_stderr:c_int
}

impl <'d,'c:'d> Channel<'c> {
    pub fn request_exec(&mut self,cmd:&[u8])->Result<(),Error> {
        let str=std::ffi::CString::new(cmd).unwrap();
        let e = unsafe {ssh_channel_request_exec(self.channel,str.as_ptr() as *const _)};
        if e==SSH_OK {
            Ok(())
        } else {
            Err(err(self.session))
        }
    }
    pub fn send_eof(&mut self)->Result<(),Error> {
        let e=unsafe { ssh_channel_send_eof(self.channel) };
        if e==0 {
            Ok(())
        } else {
            Err(err(self.session))
        }
    }
    pub fn get_exit_status(&self)->Option<c_int> {
        let e=unsafe { ssh_channel_get_exit_status(self.channel) };
        if e<0 {
            None
        } else {
            Some(e)
        }
    }
    pub fn stdout(&'d mut self)->ChannelReader<'d,'c> {
        ChannelReader { channel:self, is_stderr: 0 }
    }
    pub fn stderr(&'d mut self)->ChannelReader<'d,'c> {
        ChannelReader { channel:self, is_stderr: 1 }
    }
    pub fn close(&mut self) {
        unsafe { ssh_channel_close(self.channel) };
    }
}

impl<'b> Drop for Channel<'b> {
    fn drop(&mut self) {
        debug!("ssh_channel_free");
        unsafe { ssh_channel_free(self.channel) };
    }
}

impl <'d,'c> Read for ChannelReader<'d,'c> {
    fn read(&mut self,buf:&mut [u8])->Result<usize,std::io::Error> {
        let e=unsafe { ssh_channel_read(self.channel.channel,
                                        buf.as_mut_ptr() as *mut c_char,
                                        buf.len() as size_t,
                                        self.is_stderr) };
        if e>=0 {
            Ok(e as usize)
        } else {
            Err(std::io::Error::last_os_error())
        }
    }
}


extern "C" {
    // The "SCP subsystem"
    fn ssh_scp_new(s:*mut Session_,mode:c_int,location:*const c_char)->*mut Scp_;
    fn ssh_scp_init(s:*mut Scp_)->c_int;
    fn ssh_scp_free(s:*mut Scp_)->c_int;
    fn ssh_scp_close(s:*mut Scp_)->c_int;
    fn ssh_scp_pull_request(s:*mut Scp_)->c_int;
    fn ssh_scp_accept_request(s:*mut Scp_)->c_int;
    fn ssh_scp_deny_request(s:*mut Scp_)->c_int;
    fn ssh_scp_read(s:*mut Scp_,b:*mut c_char,st:size_t)->c_int;
    //fn ssh_scp_push_file(s:*mut Scp_,b:*const c_char,st:size_t,mode:c_int)->c_int;
    fn ssh_scp_push_file64(s:*mut Scp_,b:*const c_char,st:uint64_t,mode:c_int)->c_int;
    fn ssh_scp_push_directory(s:*mut Scp_,b:*const c_char,mode:c_int)->c_int;
    fn ssh_scp_write(s:*mut Scp_,b:*const c_char,st:size_t)->c_int;
    //fn ssh_scp_request_get_size(s:*mut Scp_)->c_int;
    fn ssh_scp_request_get_size64(s:*mut Scp_)->uint64_t;
    fn ssh_scp_request_get_permissions(s:*mut Scp_)->c_int;
    fn ssh_scp_request_get_filename(s:*mut Scp_)->*const c_char;
    fn ssh_scp_request_get_warning(s:*mut Scp_)->*const c_char;
    // integer_mode: string in octal -> integer (= atoi in octal).
    fn ssh_scp_leave_directory(s:*mut Scp_)->c_int;
    // read_string: (= read_line) done by the std::io::Read trait
    // string_mode: itoa in octal
}

#[allow(missing_copy_implementations)]
enum Scp_ {}

/// File transfer over SSH.
pub struct Scp<'b> {
    session:&'b Session,
    scp:*mut Scp_,
    size:usize
}


bitflags!{
    flags  Mode:c_int {
        const WRITE = 0x0,
        const READ = 0x1,
        const RECURSIVE = 0x10
    }
}

#[repr(C)]
#[derive(Debug)]
pub enum Request {
    /** A new directory is going to be pulled */
    NEWDIR=1,
    /** A new file is going to be pulled */
    NEWFILE,
    /** End of requests */
    EOF,
    /** End of directory */
    ENDDIR,
    /** Warning received */
    WARNING
}

impl <'b>Drop for Scp<'b> {
    fn drop(&mut self) {
        unsafe {
            debug!("ssh_scp_free");
            ssh_scp_free(self.scp);
        }
    }
}

impl <'b>Scp<'b> {
    pub fn init(&mut self)->Result<(),Error> {
        let e= unsafe {ssh_scp_init(self.scp)};
        if e==0 { Ok(()) }
        else { Err(err(self.session)) }
    }
    pub fn close(&mut self) {
        unsafe {
            ssh_scp_close(self.scp);
        }
    }

    pub fn pull_request(&mut self)->Result<Request,Error> {
        unsafe {
            let e=ssh_scp_pull_request(self.scp);
            if e>=1 && e<=5 {
                Ok(std::mem::transmute(e))
            } else {
                Err(err(self.session))
            }
        }
    }
    pub fn push_file<P:AsRef<Path>>(&mut self,path:P,size:usize,mode:usize)->Result<(),Error> {
        unsafe {
            let p=path_as_ptr(path.as_ref());
            let e=ssh_scp_push_file64(self.scp,p.as_ptr() as *const _,size as uint64_t,mode as c_int);
            if e==0 {
                Ok(())
            } else {
                Err(err(self.session))
            }
        }
    }
    pub fn push_directory<P:AsRef<Path>>(&mut self,path:P,mode:usize)->Result<(),Error> {
        unsafe {
            let p=path_as_ptr(path.as_ref());
            let e=ssh_scp_push_directory(self.scp,p.as_ptr() as *const _,mode as c_int);
            if e==0 {
                Ok(())
            } else {
                Err(err(self.session))
            }
        }
    }
    pub fn request_get_size(&mut self)->usize {
        unsafe { ssh_scp_request_get_size64(self.scp) as usize }
    }
    pub fn request_get_permissions(&mut self)->Result<usize,Error> {
        let e=unsafe { ssh_scp_request_get_permissions(self.scp) };
        if e>=0 { Ok(e as usize) } else {
            Err(err(self.session))
        }
    }
    pub fn request_get_filename(&mut self)->Result<&'b [u8],Error> {
        let e=unsafe { ssh_scp_request_get_filename(self.scp) };
        if e.is_null() {
            Err(err(self.session))
        } else {
            Ok(unsafe { std::slice::from_raw_parts(e as *const u8,libc::strlen(e)) })
        }
    }
    pub fn request_get_warning(&mut self)->Result<&'b [u8],Error> {
        let e=unsafe { ssh_scp_request_get_warning(self.scp) };
        if e.is_null() {
            Err(err(self.session))
        } else {
            Ok(unsafe { std::slice::from_raw_parts(e as *const u8,libc::strlen(e)) })
        }
    }
    pub fn accept_request(&mut self)->Result<(),Error> {
        let e= unsafe { ssh_scp_accept_request(self.scp) };
        if e==0 {
            Ok(())
        } else {
            Err(err(self.session))
        }
    }
    pub fn deny_request(&mut self)->Result<(),Error> {
        let e= unsafe { ssh_scp_deny_request(self.scp) };
        if e==0 {
            Ok(())
        } else {
            Err(err(self.session))
        }
    }
    pub fn leave_directory(&mut self)->Result<(),Error>{
        let e= unsafe { ssh_scp_leave_directory(self.scp) };
        if e==0 {
            Ok(())
        } else {
            Err(err(self.session))
        }
    }

    /// Initialize the Scp structure to use as a Reader. Not doing so will cause `read` to fail.
    pub fn reader(&mut self)->&mut Scp<'b> {
        self.size=self.request_get_size();
        self
    }
}

impl<'c> std::io::Read for Scp<'c> {
    fn read(&mut self,buf:&mut [u8])->Result<usize,std::io::Error> {
        if self.size==0 { Ok(0) } else {
            let e=
                unsafe{ ssh_scp_read(self.scp,
                                     buf.as_mut_ptr() as *mut c_char,
                                     buf.len() as size_t) };
            if e>=0 {
                self.size -= e as usize;
                Ok(e as usize)
            } else {
                Err(std::io::Error::new(std::io::ErrorKind::Other,
                                        err(self.session)))
            }
        }
    }
}


impl<'c> std::io::Write for Scp<'c> {
    fn write(&mut self,buf:&[u8])->Result<usize,std::io::Error> {
        let e=unsafe{ ssh_scp_write(self.scp,
                                    buf.as_ptr() as *mut c_char,
                                    buf.len() as size_t) };
        if e>=0 {
            Ok(e as usize)
        } else {
            Err(std::io::Error::new(std::io::ErrorKind::Other,
                                    err(self.session)))
        }
    }
    fn flush(&mut self)->Result<(),std::io::Error> {
        Ok(())
    }
}