/src/TortoisePlink/NETWORK.H

/*

 * Networking abstraction in PuTTY.

 *

 * The way this works is: a back end can choose to open any number

 * of sockets - including zero, which might be necessary in some.

 * It can register a bunch of callbacks (most notably for when 

 * data is received) for each socket, and it can call the networking

 * abstraction to send data without having to worry about blocking.

 * The stuff behind the abstraction takes care of selects and

 * nonblocking writes and all that sort of painful gubbins.

 */



#ifndef PUTTY_NETWORK_H

#define PUTTY_NETWORK_H



#ifndef DONE_TYPEDEFS

#define DONE_TYPEDEFS

typedef struct conf_tag Conf;

typedef struct backend_tag Backend;

typedef struct terminal_tag Terminal;

#endif



typedef struct SockAddr_tag *SockAddr;

/* pay attention to levels of indirection */

typedef struct socket_function_table **Socket;

typedef struct plug_function_table **Plug;



#ifndef OSSOCKET_DEFINED

typedef void *OSSocket;

#endif



struct socket_function_table {

    Plug(*plug) (Socket s, Plug p);

    /* use a different plug (return the old one) */

    /* if p is NULL, it doesn't change the plug */

    /* but it does return the one it's using */

    void (*close) (Socket s);

    int (*write) (Socket s, const char *data, int len);

    int (*write_oob) (Socket s, const char *data, int len);

    void (*write_eof) (Socket s);

    void (*flush) (Socket s);

    void (*set_private_ptr) (Socket s, void *ptr);

    void *(*get_private_ptr) (Socket s);

    void (*set_frozen) (Socket s, int is_frozen);

    /* ignored by tcp, but vital for ssl */

    const char *(*socket_error) (Socket s);

};



struct plug_function_table {

    void (*log)(Plug p, int type, SockAddr addr, int port,

		const char *error_msg, int error_code);

    /*

     * Passes the client progress reports on the process of setting

     * up the connection.

     * 

     * 	- type==0 means we are about to try to connect to address

     * 	  `addr' (error_msg and error_code are ignored)

     * 	- type==1 means we have failed to connect to address `addr'

     * 	  (error_msg and error_code are supplied). This is not a

     * 	  fatal error - we may well have other candidate addresses

     * 	  to fall back to. When it _is_ fatal, the closing()

     * 	  function will be called.

     */

    int (*closing)

     (Plug p, const char *error_msg, int error_code, int calling_back);

    /* error_msg is NULL iff it is not an error (ie it closed normally) */

    /* calling_back != 0 iff there is a Plug function */

    /* currently running (would cure the fixme in try_send()) */

    int (*receive) (Plug p, int urgent, char *data, int len);

    /*

     *  - urgent==0. `data' points to `len' bytes of perfectly

     *    ordinary data.

     * 

     *  - urgent==1. `data' points to `len' bytes of data,

     *    which were read from before an Urgent pointer.

     * 

     *  - urgent==2. `data' points to `len' bytes of data,

     *    the first of which was the one at the Urgent mark.

     */

    void (*sent) (Plug p, int bufsize);

    /*

     * The `sent' function is called when the pending send backlog

     * on a socket is cleared or partially cleared. The new backlog

     * size is passed in the `bufsize' parameter.

     */

    int (*accepting)(Plug p, OSSocket sock);

    /*

     * returns 0 if the host at address addr is a valid host for connecting or error

     */

};



/* proxy indirection layer */

/* NB, control of 'addr' is passed via new_connection, which takes

 * responsibility for freeing it */

Socket new_connection(SockAddr addr, char *hostname,

		      int port, int privport,

		      int oobinline, int nodelay, int keepalive,

		      Plug plug, Conf *conf);

Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only,

		    Conf *conf, int addressfamily);

SockAddr name_lookup(char *host, int port, char **canonicalname,

		     Conf *conf, int addressfamily);



/* platform-dependent callback from new_connection() */

/* (same caveat about addr as new_connection()) */

Socket platform_new_connection(SockAddr addr, char *hostname,

			       int port, int privport,

			       int oobinline, int nodelay, int keepalive,

			       Plug plug, Conf *conf);



/* socket functions */



void sk_init(void);		       /* called once at program startup */

void sk_cleanup(void);		       /* called just before program exit */



SockAddr sk_namelookup(const char *host, char **canonicalname, int address_family);

SockAddr sk_nonamelookup(const char *host);

void sk_getaddr(SockAddr addr, char *buf, int buflen);

int sk_hostname_is_local(const char *name);

int sk_address_is_local(SockAddr addr);

int sk_address_is_special_local(SockAddr addr);

int sk_addrtype(SockAddr addr);

void sk_addrcopy(SockAddr addr, char *buf);

void sk_addr_free(SockAddr addr);

/* sk_addr_dup generates another SockAddr which contains the same data

 * as the original one and can be freed independently. May not actually

 * physically _duplicate_ it: incrementing a reference count so that

 * one more free is required before it disappears is an acceptable

 * implementation. */

SockAddr sk_addr_dup(SockAddr addr);



/* NB, control of 'addr' is passed via sk_new, which takes responsibility

 * for freeing it, as for new_connection() */

Socket sk_new(SockAddr addr, int port, int privport, int oobinline,

	      int nodelay, int keepalive, Plug p);



Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only, int address_family);



Socket sk_register(OSSocket sock, Plug plug);



#define sk_plug(s,p) (((*s)->plug) (s, p))

#define sk_close(s) (((*s)->close) (s))

#define sk_write(s,buf,len) (((*s)->write) (s, buf, len))

#define sk_write_oob(s,buf,len) (((*s)->write_oob) (s, buf, len))

#define sk_write_eof(s) (((*s)->write_eof) (s))

#define sk_flush(s) (((*s)->flush) (s))



#ifdef DEFINE_PLUG_METHOD_MACROS

#define plug_log(p,type,addr,port,msg,code) (((*p)->log) (p, type, addr, port, msg, code))

#define plug_closing(p,msg,code,callback) (((*p)->closing) (p, msg, code, callback))

#define plug_receive(p,urgent,buf,len) (((*p)->receive) (p, urgent, buf, len))

#define plug_sent(p,bufsize) (((*p)->sent) (p, bufsize))

#define plug_accepting(p, sock) (((*p)->accepting)(p, sock))

#endif



/*

 * Each socket abstraction contains a `void *' private field in

 * which the client can keep state.

 *

 * This is perhaps unnecessary now that we have the notion of a plug,

 * but there is some existing code that uses it, so it stays.

 */

#define sk_set_private_ptr(s, ptr) (((*s)->set_private_ptr) (s, ptr))

#define sk_get_private_ptr(s) (((*s)->get_private_ptr) (s))



/*

 * Special error values are returned from sk_namelookup and sk_new

 * if there's a problem. These functions extract an error message,

 * or return NULL if there's no problem.

 */

const char *sk_addr_error(SockAddr addr);

#define sk_socket_error(s) (((*s)->socket_error) (s))



/*

 * Set the `frozen' flag on a socket. A frozen socket is one in

 * which all READABLE notifications are ignored, so that data is

 * not accepted from the peer until the socket is unfrozen. This

 * exists for two purposes:

 * 

 *  - Port forwarding: when a local listening port receives a

 *    connection, we do not want to receive data from the new

 *    socket until we have somewhere to send it. Hence, we freeze

 *    the socket until its associated SSH channel is ready; then we

 *    unfreeze it and pending data is delivered.

 * 

 *  - Socket buffering: if an SSH channel (or the whole connection)

 *    backs up or presents a zero window, we must freeze the

 *    associated local socket in order to avoid unbounded buffer

 *    growth.

 */

#define sk_set_frozen(s, is_frozen) (((*s)->set_frozen) (s, is_frozen))



/*

 * Call this after an operation that might have tried to send on a

 * socket, to clean up any pending network errors.

 */

void net_pending_errors(void);



/*

 * Simple wrapper on getservbyname(), needed by ssh.c. Returns the

 * port number, in host byte order (suitable for printf and so on).

 * Returns 0 on failure. Any platform not supporting getservbyname

 * can just return 0 - this function is not required to handle

 * numeric port specifications.

 */

int net_service_lookup(char *service);



/*

 * Look up the local hostname; return value needs freeing.

 * May return NULL.

 */

char *get_hostname(void);



/********** SSL stuff **********/



/*

 * This section is subject to change, but you get the general idea

 * of what it will eventually look like.

 */



typedef struct certificate *Certificate;

typedef struct our_certificate *Our_Certificate;

    /* to be defined somewhere else, somehow */



typedef struct ssl_client_socket_function_table **SSL_Client_Socket;

typedef struct ssl_client_plug_function_table **SSL_Client_Plug;



struct ssl_client_socket_function_table {

    struct socket_function_table base;

    void (*renegotiate) (SSL_Client_Socket s);

    /* renegotiate the cipher spec */

};



struct ssl_client_plug_function_table {

    struct plug_function_table base;

    int (*refuse_cert) (SSL_Client_Plug p, Certificate cert[]);

    /* do we accept this certificate chain?  If not, why not? */

    /* cert[0] is the server's certificate, cert[] is NULL-terminated */

    /* the last certificate may or may not be the root certificate */

     Our_Certificate(*client_cert) (SSL_Client_Plug p);

    /* the server wants us to identify ourselves */

    /* may return NULL if we want anonymity */

};



SSL_Client_Socket sk_ssl_client_over(Socket s,	/* pre-existing (tcp) connection */

				     SSL_Client_Plug p);



#define sk_renegotiate(s) (((*s)->renegotiate) (s))



#endif