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diff --git a/doc/API.html b/doc/API.html deleted file mode 100644 index 033843e..0000000 --- a/doc/API.html +++ /dev/null @@ -1,886 +0,0 @@ - <!DOCTYPE HTML SYSTEM> -<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"> -<head> -<title> -Libssh's Documentation -</title> -<link href="style.css" rel="stylesheet" type="text/css"> -</head> - -<div id="titre"> -<div align="center"> -LIBSSH API GUIDE <br> -Or everything you ever wanted to know about a simple and fast ssh library. - -</div> -</div> - -<h2> 0 Introduction</h2> - -<div class="tout"> -Before inserting ssh hooks into your programs, you must know some basics about -the ssh protocol, and understand why the ssh library must implement them. <br> -Lot of the protocols specifications are hidden by the ssh library API (of -course !) but some still needs an attention from the end-user programmer.<br> -Note that libssh is still an alpha product, and the API may vary from one -version to another. The only guess I can make is that the API won't radically -change. <br> -The SSH protocol was designed for some goals which I resume here : <br> --Privacy of data<br> --Security<br> --Authentication of the server<br> --Authentication of the client.<br> -The client MUST be sure who's speaking to before entering into any -authentication way. That's where the end programmer must ensure the given -fingerprints *are* from the legitimate server. A ssh connection must follow -the following steps:<br> -<br> -1- Before connecting the socket, you can set up if you wish one or other - server public key authentication ie. DSA or RSA. - You can choose cryptographic algorithms you trust and compression algorithms - if any.<br> -2- The connection is made. A secure handshake is made, and resulting from it, - a public key from the server is gained. - You MUST verify that the public key is legitimate.<br> -3- The client must authenticate : the two implemented ways are password, and - public keys (from dsa and rsa key-pairs generated by openssh). It is - harmless to authenticate to a fake server with these keys because the - protocol ensures the data you sign can't be used twice. It just avoids - man-in-the-middle attacks.<br> -4- Now that the user has been authenticated, you must open one or several - channels. channels are different subways for information into a single ssh - connection. Each channel has a standard stream (stdout) and an error - stream (stderr). You can theoretically open an infinity of channel.<br> -5- With the channel you opened, you can do several things :<br> - -Open a shell. You may want to request a pseudo virtual terminal before <br> - -Execute a command. The virtual terminal is usable, too<br> - -Invoke the sftp subsystem. (look at chapter 6)<br> - -invoke your own subsystem. This is out the scope of this - document but it is easy to do.<br> -6- When everything is finished, just close the channels, and then the - connection.<br> -<br> -At every place, a function which returns an error code (typically -1 for int -values, NULL for pointers) also sets an error message and an error code. -I high-lined the main steps, now that's you to follow them :) -<br> -</div> -<h2> 1- Setting the options </h2> -<div class="tout"> -The options mechanism will change during updates of the library, but the -functions which exists now will certainly be kept. -<br><br> -The ssh system needs to know the preferences of the user, the trust into one -or another algorithm and such. More important informations have to be given -before connecting : the host name of the server, the port (if non default), -the binding address, the default username, ... <br> -The options structure is given to a ssh_connect function, then this option -structure is used again and again by the ssh implementation. you shall not -free it manually, and you shall not share it with multiple sessions.<br> -Two ways are given for setting the options : the easy one (of course !) and -the long-but-accurate one.<br><br> -</div> -<h3>a) the easy way</h3><br> -<div class="tout"> -Lot of ssh options in fact come from the command line of the program... <br> -you could parse them and then use the long way for every argument, but libssh -has a mechanism to do that for you, automatically.<br> -<br> -<div class="prot"> -SSH_OPTIONS *ssh_getopt(int *argcptr, char **argv); -</div> -this function will return you a new options pointer based on the arguments -you give in parameters. <br> better, they clean the argv array from used parameters -so you can use them after in your own program<br> -<div class="ex"> -int main(int argc, char **argv){<br> - SSH_OPTIONS *opt;<br> - opt=ssh_getopt(&argc, argv);<br> - if(!opt){<br> - ...<br> - }<br> -</div> -the function will return NULL if some problem is appearing.<br> -As a matter of portability for you own programs, the hostname isn't always<br> -the first argument from the command line, so the single arguments (not -preceded by a -something) won't be parsed.<br> -<div class="ex"> -example: <br> -user@host:~$ myssh -u aris localhost <br> --u aris will be caught, localhost will not.<br> -</div> - -cfr the options_set_user() function in the next part for more informations -about it.<br> -</div> -<h3>b) the long way</h3> -<div class="tout"> -<div class="prot"> -SSH_OPTIONS *options_new(); -</div> -This function returns an empty but initialized option structure pointer.<br> -The structure is freed by ssh_disconnect described later, so don't use the -existing function options_free() (it's an internal function).<br> -So : use it only for <b>one</b> ssh_connect(), <b>never</b> free it.<br> -<br> -<div class="prot"> -SSH_OPTIONS *options_copy(SSH_OPTIONS *opt); -</div> -If you need to replicate an option object before using it, use this function. -<br><br> - -The following functions are all of the following form : <br> -<div class="prot"> -int options_set_something(SSH_OPTIONS *opt, something); -</div> -the something parameters are always internaly copied, so you don't have to -strdup them.<br> -some return eather 0 or -1, in which case an error message appears in the -error functions, others never fail (return void)<br> -the error codes and descriptions for these functions are recoverable throught <i>ssh_get_error(NULL);</i> -<br> -<div class="prot"> -int options_set_wanted_method(SSH_OPTIONS *opt,int method, char *list); -</div> -Passing an option structure, a ssh macro for the method, and a list of allowed -parameters indicates libssh you want to use these.<br> -The macros are :<br> -KEX_ALGO<br> -KEX_HOSTKEY Server public key type expected<br> -KEX_CRYPT_C_S 2 Cryptographic algorithm client->server<br> -KEX_CRYPT_S_C 3 Cryptographic algorithm server->client<br> -KEX_MAC_C_S 4<br> -KEX_MAC_S_C 5<br> -KEX_COMP_C_S 6 Compression method for the stream ("zlib" or "none"), client to server<br> -KEX_COMP_S_C 7 Compression method for the stream ("zlib" or "none"), server to client<br> -KEX_LANG_C_S 8<br> -KEX_LANG_S_C 9<br> -<br> -Currently, only KEX_HOSTKEY and ,KEX_CRYPT_C_S,S_C, KEX_COMP_C_S and S_C work -as expected. the list is a comma separated string of prefered -algorithms/methods, in order of preference.<br> -<br> -<div class="ex"> -example : this sets the ssh stream to be compressed in client->server mode only -<br> - -ret = option_set_wanted_method(options,KEX_COMP_C_S,"zlib"); -</div> -<div class="ex"> -example: this will set the cryptographic algorithms wanted from server to -client to aes128-cbc and then aes192-cbc if the first one isn't supported by -server:<br> -ret = option_set_wanted_method(options,KEX_CRYPT_S_C,"aes128-cbc,aes192-cbc"); -</div> -<div class="ex"> -if you prefer getting the Dss key from a server instead of rsa, but you still -accept rsa if dss isn't available :<br> -options_set_wanted_method(options,KEX_HOSTKEY,"ssh-dss,ssh-rsa"); -</div> -return value: <br>0 if the option is valid, -1 else.<br> An error is set in that case. -<br><br> -<div class="prot"> -void options_set_port(SSH_OPTIONS *opt, unsigned int port); -</div> -this function sets the server port. -<div class="prot"> -void options_set_host(SSH_OPTIONS *opt, const char *hostname); -</div> -this function sets the hostname of the server. It also supports -"user@hostname" syntax in which case the user options is set too. -<div class="prot"> -void options_set_fd(SSH_OPTIONS *opt, int fd); -</div> -permits you to specify an opened file descriptor you've opened yourself. -<br> -It's a good way of bypassing the internal FD opening in libssh, but there are things you should take care of : <br> --The file descriptor should be returned to libssh without nonblocking settings<br> --If you wish to use <i>is_server_known()</i> You should also set <i>options_set_host</i>... Otherwise libssh won't have any mean of certifying the server is known or not.<br><br> -<div class="prot"> -void options_set_bindaddr(SSH_OPTIONS *opt, char *bindaddr); -</div> -this function allows you to set the binding address, in case your computer has -multiple IP or interfaces. it supports both hostnames and IP's -<br><br> -<div class="prot"> -void options_set_username(SSH_OPTIONS *opt,char *username); -</div> -sets username for authenticating in this session. -<br><br> - -<div class="prot"> -void option_set_timeout(SSH_OPTIONS *opt,long seconds, long usec); -</div> -sets the timeout for connecting to the socket. It does not include a timeout for the name resolving or handshake. -<br> -<br> -<div class="prot"> -void options_set_ssh_dir(SSH_OPTIONS *opt, char *dir); -</div> -this function sets the .ssh/ directory used by libssh. You may use a %s -which will be replaced by the home directory of the user. -NEVER accept parameters others than the user's one, they may contain -format strings which are a security hole if a malicious agent gives it. -<br><br> -<div class="prot"> -void options_set_known_hosts_file(SSH_OPTIONS *opt, char *dir); -</div> -same than <i>options_set_ssh_dir()</i> for known_hosts file. -<br><br> -<div class="prot"> -void options_set_identity(SSH_OPTIONS *opt, char *identity); -</div> -same than upper for the identity file (they come by pair, the one asked is the file without the .pub suffix) -<br><br> -<div class="prot"> -void options_set_status_callback(SSH_OPTIONS *opt, void (*callback)(void *arg, float status), void *arg); -</div> -Because more and more developpers use libssh with GUI, I've added this function to make the ssh_connect function more -interactive. This permits to set a callback of the form -<div class="prot">void function(void *userarg, float status);</div> with status going from 0 to 1 during ssh_connect. The callback won't ever be called after the connection is made. -<br><br> -</div> -<h2> -2- Connecting the ssh server -</H2> -<div class="tout"> -The API provides an abstract data type, SSH_SESSION, which describes the -connection to one particular server. You can make several connections to -different servers under the same process because of this structure. -<br> -<br> -<div class="prot"> -SSH_SESSION *ssh_connect(SSH_OPTIONS *options); -</div> -This function returns a handle on the newly connection. This function expects -to have a pre-set options structure. -<br> -It returns NULL in case of error, in which case you can look at error messages -for more informations. -<br><br> -<div class="prot"> -void ssh_disconnect(SSH_SESSION *session); -</div> -This function sends a polite disconnect message, and does clean the session.<br> -This is the proper way of finishing a ssh connection.<br> -<br> -<div class="prot"> -int ssh_get_pubkey_hash(SSH_SESSION *session, char hash[MD5_DIGEST_LEN]); -</div> -This function places the MD5 hash of the server public key into the hash array.<br> -It's IMPORTANT to verify it matches the previous known value. One server always -have the same hash. No other server/attacker can emulate it (or it'd be caught -by the public key verification procedure automatically made by libssh). -<br> -You can skip this step if you correctly handle <i>is_server_known()</i> -<br><br> -<div class="prot"> -int ssh_is_server_known(SSH_SESSION *session); -</div> - -Checks the user's known host file to look for a previous connection to the specified server. Return values:<br> -SSH_SERVER_KNOWN_OK : the host is known and the key has not changed<br> -SSH_SERVER_KNOWN_CHANGED : The host's key has changed. Either you are under -an active attack or the key changed. The API doesn't give any way to modify the key in known hosts yet. I Urge end developers to WARN the user about the possibility of an attack.<br> -SSH_SERVER_FOUND_OTHER: The host gave us a public key of one type, which does -not exist yet in our known host file, but there is an other type of key which is know.<br> -IE server sent a DSA key and we had a RSA key.<br> -Be carreful it's a possible attack (coder should use option_set_wanted_method() to specify -which key to use).<br> -SSH_SERVER_NOT_KNOWN: the server is unknown in known hosts. Possible reasons : -case not matching, alias, ... In any case the user MUST confirm the Md5 hash is correct.<br> -SSH_SERVER_ERROR : Some error happened while opening known host file.<br> -<br> -<div class="prot"> -int ssh_write_knownhost(SSH_SESSION *session); -</div> -write the current connected host as known in the known host file. returns a negative value if something went wrong. You generaly use it when ssh_is_server_known returned SSH_SERVER_NOT_KNOWN. -<br><br> -<div class="prot"> -int pubkey_get_hash(SSH_SESSION *session,char hash[MD5_DIGEST_LEN]); -</div> -deprecated but left for binary compatibility (will be removed in newer versions). -</div> - -<h2>3- Authenticating to server</h2> -<div class="tout"> -The ssh library supports the two most used authentication methods from SSH. -In every function, there is a "username" argument. If null is given instead, -the server will use the default username (which is guessed from what you gave -to options_set_user or options_set_hostname or even the local user running the code). -<br> - -Authentication methods :<br> -<h3>A) Public keys</h3><br> - The public key is the only method which does not compromise your key if the - remote host has been compromised (the server can't do anything more than - getting your public key). This is not the case of a password authentication - (the server can get your plaintext password).<br> - Libssh is obviously fully compatible with the openssh public and private keys.<br> - The things go this way : you scan a list of files which contain public keys.<br> - For each key, you send it to ssh server until the server acknowledges a key - (a key it knows). Then, you get the private key for this key and send a - message proving you own that private key.<br> - Here again, two ways for the public key authentication... the easy and the - complicated one.<br> -<br> -<h4> easy way:</h4> -<div class="prot"> -int ssh_userauth_autopubkey(SSH_SESSION *session); -</div> -This function will try the most common places for finding the public and - private keys (your home directory) or eventualy the identity files asked by - the <i>options_set_identity()</i> function.<br> - The return values are :<br> - SSH_AUTH_ERROR : some serious error happened during authentication<br> - SSH_AUTH_DENIED : no key matched<br> - SSH_AUTH_SUCCESS : you are now authenticated<br> - SSH_AUTH_PARTIAL : some key matched but you still have to give an other mean - of authentication (like password).<br> -<br> -<h4> peanful way:</h4> - there are three steps : you get a public key, you ask the server if the key - matches a known one, if true, you get the private key and authenticate with - it.<br> - <div class="prot"> - STRING *publickey_from_file(char *filename,int *_type); -</div> -will return an handle on a public key. if you give a pointer to an int, - a symbolic value will be placed there. Do it because you need it in next - step.<br><br> -<div class="prot"> - int ssh_userauth_offer_pubkey(SSH_SESSION *session, char *username, - int type, STRING *publickey); - </div> - this function will offer a public key to the server. SSH_AUTH_SUCCESS is - returned if the key is accepted (in which case you'll want to get the - private key), SSH_AUTH_DENIED otherwise.<br> - Still watch for SSH_AUTH_ERROR as connection problems might happen. -<br> - in case of SSH_AUTH_SUCCESS, - <br> - <div class="prot"> - PRIVATE_KEY *privatekey_from_file(SSH_SESSION *session,char *filename, - int type,char *passphrase); - </div> - will get the privatekey from the filename previously set by - publickey_from_next_file(). You can call it with a passphrase for - unlocking the key. If passphrase==NULL, the default prompt will be used.<br> - The function returns NULL if the private key wasn't opened - (ie bad passphrase or missing file).<br> -<br> -<div class="prot"> - int ssh_userauth_pubkey(SSH_SESSION *session, char *username, - STRING *publickey, PRIVATE_KEY *privatekey); -</div> - Will try to authenticate using the public and private key. It shall return - SSH_AUTH_SUCCESS if you are authenticated, SSH_AUTH_ERROR, SSH_AUTH_DENIED or - SSH_AUTH_PARTIAL depending of return condition.<br> - - each public key (of type STRING) must be freed with the libc "free" function.<br> - The private key must be freed with private_key_free(PRIVATE_KEY *) which - will clean the memory before (don't worry about passphrase leaking).<br> - <br> - -<h3> B) Password</h3><br> - <div class="prot"> - int ssh_userauth_password(SSH_SESSION *session,char *username,char *password); - </div> - Will return SSH_AUTH_SUCCESS if the password matched, one of other constants - otherwise. It's your work to ask the password and to free it in a secure - manner.<br><br> - -<h3> C) Keyboard-interactive</h3><br> - <div class="prot"> - int ssh_userauth_kbdint(SSH_SESSION *session, char *user, char *submethods); - </div> - This is the main keyboard-interactive function. It will return SSH_AUTH_SUCCESS,SSH_AUTH_DENIED, SSH_AUTH_PARTIAL, SSH_AUTH_ERROR depending on the result of the request.<br> - The keyboard-interactive authentication method of SSH2 is a feature which permits the server to ask a certain number of questions in an interactive manner to the client, until it decides to accept or deny the login.<br> - To begin, you call this function (you can omit user if it was set previously and omit submethods - instead you know what you do - just put them to NULL) and store the answer. - If the answer is SSH_AUTH_INFO, it means the server has sent a few questions to ask your user, which you can retrieve with the following functions. Then, set the answers and call back ssh_userauth_kbdint with same arguments. It may again ask a few other questions etc. until you get an other SSH_AUTH code than SSH_AUTH_INFO.<br> - Few remarks :<br> - -Even the first call can return SSH_AUTH_DENIED or SSH_AUTH_SUCCESS.<br> - -The server can send an empty question set (this is the default behavior on my system) after you have sent the answers to the first questions. - you must still parse the answer, it might contain some message from the server saying hello or such things. Just call ssh_userauth_kbdint() once more<br> -<br> - <div class="prot"> -int ssh_userauth_kbdint_getnprompts(SSH_SESSION *session); - </div> -After you called ssh_userauth_kbdint and got SSH_AUTH_INFO, the session contains a few questions (or prompts) from the server. This function returns the number of prompts and answers.<br> -It could be zero, in which case you must act as said previously.<br> - -<div class="prot"> - char *ssh_userauth_kbdint_getname(SSH_SESSION *session); -</div> - this functions returns the "name" of the message block. The meaning is explained later.<br> - This function returns a pointer that stays valid until the next ssh_userauth_kbdint() call and must not be freed.<br> - -<div class="prot"> - char *ssh_userauth_kbdint_getinstruction(SSH_SESSION *session); -</div> - this functions returns the "instruction" of the message block. The meaning is explained later.<br> -This function returns a pointer that stays valid until the next ssh_userauth_kbdint() call and must not be freed.<br> - -<div class="prot"> - char *ssh_userauth_kbdint_getprompt(SSH_SESSION *session,int i, char *echo); -</div> -This functions returns a pointer to the nth prompt. The character pointed by echo, if different from null, will contain a boolean value after the call, which means that the user prompt must be echoed or not.<br> -zero means that the echo is Off (like for a password prompt).<br> -any other value means the echo is on.<br> -This function returns a pointer that stays valid until the next ssh_userauth_kbdint() call and must not be freed.<br> - -<div class="prot"> -void ssh_userauth_kbdint_setanswer(SSH_SESSION *session, unsigned int i, char *a -nswer); -</div> -This function sets the ith answer. The string you give will be duplicated, and this copy will be discarded once it is no longer necessary.<br> -care must be taken so you discard the content of the original string after this function call.<br> - -<h3> A little note about how to use the informations from keyboard-interactive authentication</h3> -<br> -The words from the original drafts explain everything -<div class="prot"> -3.3 User Interface - -Upon receiving a request message, the client SHOULD prompt the user -as follows:<br> - A command line interface (CLI) client SHOULD print the name and - instruction (if non-empty), adding newlines. Then for each prompt in - turn, the client SHOULD display the prompt and read the user input.<br> -<br> -A graphical user interface (GUI) client has many choices on how to -prompt the user. One possibility is to use the name field (possibly -prefixed with the application's name) as the title of a dialog window -in which the prompt(s) are presented. In that dialog window, the -instruction field would be a text message, and the prompts would be -labels for text entry fields. All fields SHOULD be presented to the -user, for example an implementation SHOULD NOT discard the name field -because its windows lack titles; it SHOULD instead find another way -to display this information. If prompts are presented in a dialog -window, then the client SHOULD NOT present each prompt in a separate -window.<br> -<br> -All clients MUST properly handle an instruction field with embedded -newlines. They SHOULD also be able to display at least 30 characters -for the name and prompts. If the server presents names or prompts -longer than 30 characters, the client MAY truncate these fields to -the length it can display. If the client does truncate any fields, -there MUST be an obvious indication that such truncation has occured.<br> -The instruction field SHOULD NOT be truncated.<br> -Clients SHOULD use control character filtering as discussed in -[SSH-ARCH] to avoid attacks by including terminal control characters -in the fields to be displayed.<br> -<br> -For each prompt, the corresponding echo field indicates whether or -not the user input should be echoed as characters are typed. Clients -SHOULD correctly echo/mask user input for each prompt independently -of other prompts in the request message. If a client does not honor -the echo field for whatever reason, then the client MUST err on the -side of masking input. A GUI client might like to have a checkbox -toggling echo/mask. Clients SHOULD NOT add any additional characters -to the prompt such as ": " (colon-space); the server is responsible -for supplying all text to be displayed to the user. Clients MUST -also accept empty responses from the user and pass them on as empty -strings.<br> - -</div> -<br> -<h3> D) "none"</h3><br> - In fact this mode only serve to get the list of supported authentications.<br> - however, it also serves to get the banner message from the server, if any.<br> - You should firstly try this method, at least for getting the banner, then to enter if there is no password at all.<br> - <div class="prot"> - int ssh_userauth_none(SSH_SESSION *session, char *username); - </div> - if the account has no password (and the server is configured to let you - pass), the function might answer SSH_AUTH_SUCCESS. That's why - ssh_auth_autopubkey already calls it for you. -<br><br> -<div class="prot"> - char *ssh_get_issue_banner(SSH_SESSION *session); -</div> -if during authentication, the server has given a banner, you can get it - this way. the function returns NULL if no banner exists, and you have to - free the returned pointer.<br><br> -</div> - -<h2>4- Opening a channel</h2> -<div class="tout"> -Maybe you want to use the sftp subsystem : all this is done for you, you -better read at the end of the paper how to use the sftp functions.<br> -You probably want to open one or more shells, or call one or more programs.<br> - -So you need a channel.<br> -<div class="prot"> - CHANNEL *channel; -</div> -This is an handler to a channel object. it describes your channel. -<br> -<div class="prot"> -CHANNEL *channel_open_session(SSH_SESSION *session); -</div> -This will open a channel for use into a session (which can be used for executing -a command or a shell. Not for tcp forwarding).<br> -The function returns NULL if for a reason or another the channel can't be -opened.<br> -<i> -CHANNEL *open_session_channel(...)</i> is deprecated and should not be used in future -applications.<br><br> -<div class="prot"> -CHANNEL *channel_open_forward(SSH_SESSION *session, char *remotehost, - int remoteport, char *sourcehost, int localport); -</div> -Ask the server to tunnel a TCP connection. The server will connect to - remotehost:remoteport and libssh will return an handle to the channel if it is allowed.<br> - Otherwise, NULL will be returned. sourcehost and localport are generaly - used in message debugging purpose and have no effect on the result.<br> - <br> -When you've finished with your channel, you may send an EOF message and -then close it :<br> -<div class="prot"> -void channel_send_eof(CHANNEL *channel); -</div> -sends an end of file into channel. It doesn't close the channel and you can still read it.<br><br> - -<div class="prot"> -void channel_free(CHANNEL *channel); -</div> -closes and destroy the channel. -<br> -<div class="prot"> -void channel_close(CHANNEL *channel); -</div> -sends an EOF and close the channel. (if you don't know what to do, use channel_free). It doesn't free the channel. - -</div> -<h2>5- The shell</h2> -<div class="tout"> -<div class="prot"> -int channel_request_env(CHANNEL *channel, char *name, char *value); -</div> -Ask the server to set the "name" environment variable to "value". For security - reasons, some variables won't be accepted by the server. It returns 0 otherwise.<br><br> -<div class="prot"> -int channel_request_pty(CHANNEL *channel); -</div> - ask the server to allocate a pseudo terminal for the current channel.<br> - the function returns 0 on success.<br><br> - -<div class="prot"> -int channel_request_pty_size(CHANNEL *channel, char *terminal, int cols, int rows); -</div> -ask the server to allocate a pty. The terminal parameter is the type of pty -(vt100,xterm,...), cols and rows are the size of the new terminal (80x24 by example).<br><br> -<div class="prot"> -int channel_change_pty_size(CHANNEL *channel, int cols,int rows); -</div> -changes the window size (terminal) of the current session;<br><br> -<div class="prot"> -int channel_request_shell(CHANNEL *channel); -</div> -This function requests a shell. After its success, a shell is running at the other side of the channel.<br><br> -<div class="prot"> -int channel_request_exec(CHANNEL *channel, char *cmd); -</div> -run a shell command without an interactive shell, ie $SHELL -c "command".<br> - returns 0 on success.<br><br> - -You might ask the server to open a subsystem for you. this is done this way : -<div class="prot"> -int channel_request_subsystem(CHANNEL *channel, char *subsystem); -</div> -There are some functions used to manipulate the channels : -<br><br> -<div class="prot"> -int channel_write(CHANNEL *channel,void *data,int len); -</div> -writes len bytes of data into the channel. It returns the number of bytes written. The current implementation is a blocking write -of the complete data buffer, but it may vary.<br><br> -<div class="prot"> -int channel_read(CHANNEL *channel, BUFFER *buffer,int bytes,int is_stderr); -</div> -It makes a blocking read on the channel, of "bytes" bytes and returns the - result into an allocated buffer you passed in. (with <i>buffer_new()</i>).<br> - it will read on stderr, if is_stderr is set.<br> - The function might read less bytes than "bytes" variable if an End of File - happened. Otherwise, the function will always block reading until "bytes" - bytes are read.<br> - with "bytes"=0, <i>channel_read()</i> will read the current state of the read buffer, but will read at least one byte (and block if nothing is available, except EOF case).<br> - - You don't need to free and allocate a new buffer each time you call this function, just pass the same object each time.<br> - look at the <i>buffer_</i> functions further for the correct way of retrieving the data.<br><br> - -<div class="prot"> -int channel_read_nonblocking (CHANNEL *channel, char *dest, int len, int is_stderr); -</div> -Non-blocking read on channel, at most len bytes of data are read. Returns 0 if EOF or if no data available. -<br><br> -<div class="prot"> -int channel_is_open(CHANNEL *channel); -</div> - returns 0 if the channel has been closed by remote host, something else otherwise.<br><br> -<div class="prot"> -int channel_poll(CHANNEL *channel, int is_stderr); -</div> - This nonblocking function returns the number of bytes immediatly available for - reading on the channel and stdin/stderr.<br><br> - -More interesting, if you are going to do channel multiplexing, this function -is for you :<br><br> -<div class="prot"> -int ssh_select(CHANNEL **channels,CHANNEL **outchannels, int maxfd, - fd_set *readfds, struct timeval *timeout); -</div> -channels is an array of channel pointers, finished by a NULL pointer.<br> - It can be used ever and ever, as it is never written.<br> - outchannels is an array of size at least greater or equal to "channels".<br> - It hasn't to be initialized.<br> - maxfd is the maximum file descriptor from your own filedescriptors.<br> - readfds is a pointer to a fd_set structure, like in the original - select implementation (man select).<br> - the struct timeval *timeout has the same meaning than in - select(2) (man select).<br> - - There is no support for writing or special events as in <i>select(2)</i> yet.<br> -The function returns -1 if an error occured, or SSH_EINTR if select was interrupted by a syscall. This is not an error, you may restart the function.<br> -<b>note about signals:</b> libssh is not threadsafe, and most functions are not -reetrant when using the same data structures : it means you *cannot* do anything -with a channel from a ssh session passed to <i>ssh_select</i> during a signal. -<br>take a look at sample.c on how to bypass that limitation.<br> -the function works this way : it returns in the readfds the filedescriptors which have data ready for reading (the given filedescriptors have a greatest priority).<br> -Then, if no file descriptor can be read, the function looks for every -channel from the array to get a channel with data bufferized. If nothing is -available, it waits for activity on any channel/file descriptor and returns -immediatly, or waits until timeout.<br> -You will find the channels that can be read in the outchannels array (finished by NULL) and the filedescriptors in your fd_set (man FD_ISSET).<br> -this is the "heart" of your main loop.<br> -<br> -<h3>The BUFFER object.</h3> -Reading is done through the BUFFER object. here is the public interface : -<br> -<div class="prot"> -BUFFER *buffer_new(); -</div> -creates a buffer object. -<br><br> -<div class="prot"> -void *buffer_get(BUFFER *buffer); -</div> -returns a pointer to the begining of buffer. -<br><br> -<div class="prot"> -int buffer_get_len(BUFFER *buffer); -</div> -returns buffer's data size. -<br><br> -<div class="prot"> -void buffer_free(BUFFER *buffer); -</div> -destoys the buffer. -<br> -<br> -How to use the buffer system when you've read something:<br> -I've seen people doing such code:<br> -<div class="prot"> -char buffer[256];<br> -channel_read(channel,buf,1234,0);<br> -strcpy(buffer,buf.data);<br> -</div> -The correct way of doing this: -<div class="prot"> -char buffer[256];<br> -int i;<br> -i=channel_read(channel,buf,1234,0);<br> -if(i<=0)<br> - go_out()...<br> -if(i>=256)<br> - i=255;<br> -memcpy(buffer,buffer_get(buf),i);<br> -buffer[i]=0; -</div> -Do not expect the buffer to be null-terminated. Don't access the internal structure of buffer. Check the sizes before copying.<br> -</div> -<h2>6- The SFTP subsystem</h2> -<div class="tout"> -SFTP is a secure implementation of a file transfer protocol. The current -implemented version is 3. All functions aren't implemented yet but the most -important are.<br> -<br> -<h3>A) Opening the session</h3> -<div class="prot"> - SFTP_SESSION *sftp_new(SSH_SESSION *session); - int sftp_init(SFTP_SESSION *sftp); -</div> - The former returns a SFTP_SESSION handle. It returns NULL if things didn't - work as expected.<br> - sftp_init makes some initialisation work. It returns 0 if things went right. - Both of them must be called.<br> -<h3>B) Opening and reading a directory</h3> -<div class="prot"> - SFTP_DIR *sftp_opendir(SFTP_SESSION *session, char *path); -</div> - opens a directory for file listing. Returns NULL in error case. - <br><br> -<div class="prot"> - SFTP_ATTRIBUTES *sftp_readdir(SFTP_SESSION *session, SFTP_DIR *dir); -</div> -This function reads one file attribute from an opened directory. It - returns NULL if the directory is EOF, or if something wrong happened. -<br><br> -<div class="prot"> - int sftp_dir_eof(SFTP_DIR *dir); -</div> - When a <i>sftp_readdir()</i> returned NULL, you can use this function to - tell if an EOF occured. the function returns 0 if no EOF occured. - <br><br> - <div class="prot"> - void sftp_attributes_free(SFTP_ATTRIBUTES *file); -</div> -You have to free any SFTP_ATTRIBUTE structure given by an other function - with it.<br><br> -<div class="prot"> - int sftp_dir_close(SFTP_DIR *dir); -</div> -closes an opened directory. returns 0 when no error occured. -<br><br> -<h3>C) Opening, reading, writing files</h3> -<div class="prot"> - SFTP_FILE *sftp_open(SFTP_SESSION *session, char *file, int access, - SFTP_ATTRIBUTES *attr); -</div> -Opens a file. The access flags are the same than the stdio flags.<br> -see open(2) for more details.<br> -attr are the wanted attributes for the new file. If you supply NULL, - default values will be used.<br> -rem: more work is going on parsing/making the attributes structure -<br><br> -<div class="prot"> - int sftp_read(SFTP_FILE *file, void *dest, int len); -</div> -read on a file. Works as the fread() function. It is blocking by default but you can change the default behaviour with <i>sftp_file_set_nonblocking()</i>. - <br><br> -<div class="prot"> - void sftp_file_set_nonblocking(SFTP_FILE *file); -</div> -sets the file non blocking. reads on this file won't ever block. You can't detect end of files this way.<br> -*** TODO more work going there for EOF **** -<br><br> -<div class="prot"> - void sftp_file_set_blocking(SFTP_FILE *file); -</div> -restore the default setting of sftp_read. -<br><br> -<div class="prot"> - int sftp_write(SFTP_FILE *file, void *source, int len); -</div> -works as fwrite() function. It is a blocking write.<br> -<br> -<div class="prot"> - void sftp_seek(SFTP_FILE *file, int new_offset); -</div> -seek into the file for reading/writing at an other place. -<br><br> -<div class="prot"> - unsigned long sftp_tell(SFTP_FILE *file); -</div> -returns the current offset (both writing and reading) into the opened file. -<br><br> -<div class="prot"> - void sftp_rewind(SFTP_FILE *file); -</div> - same as sftp_seek(file,0); -<br><br> -<div class="prot"> - int sftp_file_close(SFTP_FILE *file); -</div> - closes a file handle. returns 0 in no error case. -<br><br> -<div class="prot"> - int sftp_rm(SFTP_SESSION *sftp, char *file); -</div> -deletes a file. -<br><br> -<div class="prot"> - int sftp_rmdir(SFTP_SESSION *sftp, char *directory); -</div> -<br> -deletes a directory. -<br><br> -<div class="prot"> - int sftp_mkdir(SFTP_SESSION *sftp, char *directory, SFTP_ATTRIBUTES *attr); -</div> -makes a directory, with the given attributes. You can't pass NULL for attr and hope it works. - <br><br> -<div class="prot"> - int sftp_rename(SFTP_SESSION *sftp, char *original, char *newname); -</div> -changes the name of a file or directory. -<br><br> -<div class="prot"> - int sftp_setstat(SFTP_SESSION *sftp, char *file, SFTP_ATTRIBUTES *attr); -</div> -changes the attributes of a file or directory. -<br><br> -<div class="prot"> - char *sftp_canonicalize_path(SFTP_SESSION *sftp, char *path); -</div> - gives the canonicalized form of some path. You have to - free the pointer given in return.<br> - (returns NULL if error). -<br><br> - - (a function to make proper SFTP_ATTRIBUTES structures is on the way ) - -<h3>D) Closing the session</h3> -<div class="prot"> - void sftp_free(SFTP_SESSION *sftp); -</div> -it closes the sftp channel and subsystem. -</div> - -<h2>7- Handling the errors</h2> -<div class="tout"> -When some function returns an error code, it's allways possible to get an -english message describing the problem. the function ssh_get_error() -returns a pointer to the static error buffer.<br> -ssh_error_code() returns the error code number. it's declared as an enum:<br> -SSH_NO_ERROR, SSH_REQUEST_DENIED, SSH_INVALID_REQUEST, SSH_CONNECTION_LOST, -SSH_FATAL, SSH_INVALID_DATA.<br><br> -SSH_REQUEST_DENIED means the ssh server refused your request but the situation is -recoverable. the others mean something happened to the connection (some -encryption problems, server problems, library bug, ...).<br> -SSH_INVALID_REQUEST means the library got some garbage from server. (But might be -recoverable).<br> -SSH_FATAL means the connection has an important problem and isn't probably -recoverable.<br> -<br> -Most of time, the error returned are SSH_FATAL, but some functions (generaly the -<i>ssh_request_*</i> ones) may fail because of server denying request. In these cases, SSH_REQUEST_DENIED is returned.<br><br> - -You'll see in the prototype SSH_SESSION *session. That's because for thread -safety, error messages that can be attached to a session aren't static -anymore. So, any error that could happen during ssh_getopt(), options_* or -ssh_connect() will be retreavable giving NULL as argument.<br> -<br> -<div class="prot"> -char *ssh_get_error(SSH_SESSION *session); -</div> -returns a pointer to a static message error from the given session. No -message freeing is needed.<br><br> -<div class="prot"> -enum ssh_error ssh_get_error_code(SSH_SESSION *session); -</div> -returns the error code that last happened along with the message. -<br><br> -</div> - -<h2>8- Final word</h2> -<div class="tout"> -I made this library because nothing in the Open source or free software community was existing yet. This project is a very personnal one as it's the first "useful" thing I ever wrote. -I hope it fits your needs, but remember the experimental state of libssh : if -something doesn't work, please mail me. If something lacks, please ask for it. -If something stinks, please write a patch and send it ! -</div> - -</body> -</html> diff --git a/doc/style.css b/doc/style.css deleted file mode 100644 index 7781182..0000000 --- a/doc/style.css +++ /dev/null @@ -1,184 +0,0 @@ - -body { -background-color:#ddf; -/*background-image:url(../back6.jpg);*/ -margin:10px 10px 10px 10px; -} - -h1 { -font-family:verdana, sans-serif; -font-size:80%; -color:black; -background-color:transparent; -text-align:left; -} -h2 { -font-family:verdana, sans-serif; -font-size:100%; -color:black; -background-color:transparent; -text-align:left; -} -h3 { -font-family:verdana, sans-serif; -font-size:80%; -color:black; -background-color:transparent; -text-align:left; -} -p { -font-family:verdana, sans-serif; -font-size:80%; -color:black; -background-color:transparent; -text-align:left; -margin-left:0px; -margin-right:0px; -} -li { -font-family:verdana, sans-serif; -font-size:80%; -color:black; -background-color:transparent; -text-align:left; -margin-left:0px; -margin-right:0px; -} -a:link { -font-family:verdana, sans-serif; -font-size:100%; -color:black; -background-color:transparent; -text-decoration:underline; -} -a:visited { -font-family:verdana, sans-serif; -font-size:100%; -color:black; -background-color:transparent; -text-decoration:underline; -} -a:hover { -font-family:verdana, sans-serif; -font-size:100%; -color:black; -background-color:transparent; -text-decoration:underline; -} - -table { -border-color:transparent; -border-style:solid; -border-width:1px; -} - -td { -font-family:verdana, sans-serif; -font-size:80%; -color:black; -text-align:left; -background-color:transparent; -border-color:transparent; -border-style:solid; -border-width:1px; -} - -.tout { - margin: 5px; - padding: 0px; - border: 2px solid #aac; - background: #eef; - } - -.prot { -border-style:solid; -border-width:2px; -border-color:#88F; -padding: 4px; -background-color:#cce; -margin: 5px 5px 5px 5px; -} - -.ex { -border-style:solid; -border-width:2px; -border-color:#aaF; -padding: 4px; -background-color:#dde; -margin: 5px 5px 5px 5px; -} -.desc { -border-style:solid; -border-width:3px; -border-color:#66F; -padding: 4px; -background-color:#aac; -margin: 15px 5px 20px 5px; -} - -#titre { - margin: 5px; - padding: 0px; - border: 5px solid #aac; - background: #eef; - } - -#gauche { - float:left; - margin: 5px; - padding: 4px; - border: 5px solid #aac; - background: #bbf; - width: 130px; - } - -#droite { - position: relative; - top:5px; - left:165px; - margin: 5px 170px 5px 5px; - padding: 10px; - border: 5px solid #aac; - background: #bbf; -} - -/* boutons */ - -a.bouton:link{ -width:128px; -height:34px; -text-decoration:none; -color:#aaa; -text-align:center; -font-weight:bold; -/*background-color:#444;*/ -background-image:url(noclicked.png); -} - -a.bouton:visited{ -width:128px; -height:34px; -text-decoration:none; -color:#aaa; -text-align:center; -font-weight:bold; -/*background-color:#444;*/ -background-image:url(noclicked.png); -} - -a.bouton:hover{ -width:128px; -height:34px; -text-decoration:none; -color:white; -text-align:center; -font-weight:bold; -/*background-color:#888;*/ -background-image:url(clicked.png); -} - -.bouton{ - text-align:center; -display:block; -} - |