/*
* 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
#include "defs.h"
typedef struct SocketVtable SocketVtable;
typedef struct PlugVtable PlugVtable;
struct Socket {
const struct SocketVtable *vt;
};
struct SocketVtable {
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);
size_t (*write) (Socket *s, const void *data, size_t len);
size_t (*write_oob) (Socket *s, const void *data, size_t len);
void (*write_eof) (Socket *s);
void (*flush) (Socket *s);
void (*set_frozen) (Socket *s, bool is_frozen);
/* ignored by tcp, but vital for ssl */
const char *(*socket_error) (Socket *s);
SocketPeerInfo *(*peer_info) (Socket *s);
};
typedef union { void *p; int i; } accept_ctx_t;
typedef Socket *(*accept_fn_t)(accept_ctx_t ctx, Plug *plug);
struct Plug {
const struct PlugVtable *vt;
};
struct PlugVtable {
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.
* - type==2 means that error_msg contains a line of generic
* logging information about setting up the connection. This
* will typically be a wodge of standard-error output from a
* proxy command, so the receiver should probably prefix it to
* indicate this.
*/
void (*closing)
(Plug *p, const char *error_msg, int error_code, bool 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()) */
void (*receive) (Plug *p, int urgent, const char *data, size_t 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, size_t 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, accept_fn_t constructor, accept_ctx_t ctx);
/*
* `accepting' is called only on listener-type sockets, and is
* passed a constructor function+context that will create a fresh
* Socket describing the connection. It returns nonzero if it
* doesn't want the connection for some reason, or 0 on success.
*/
};
/* proxy indirection layer */
/* NB, control of 'addr' is passed via new_connection, which takes
* responsibility for freeing it */
Socket *new_connection(SockAddr *addr, const char *hostname,
int port, bool privport,
bool oobinline, bool nodelay, bool keepalive,
Plug *plug, Conf *conf);
Socket *new_listener(const char *srcaddr, int port, Plug *plug,
bool local_host_only, Conf *conf, int addressfamily);
SockAddr *name_lookup(const char *host, int port, char **canonicalname,
Conf *conf, int addressfamily, LogContext *logctx,
const char *lookup_reason_for_logging);
bool proxy_for_destination (SockAddr *addr, const char *hostname, int port,
Conf *conf);
/* platform-dependent callback from new_connection() */
/* (same caveat about addr as new_connection()) */
Socket *platform_new_connection(SockAddr *addr, const char *hostname,
int port, bool privport,
bool oobinline, bool nodelay, bool 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);
bool sk_addr_needs_port(SockAddr *addr);
bool sk_hostname_is_local(const char *name);
bool sk_address_is_local(SockAddr *addr);
bool 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, bool privport, bool oobinline,
bool nodelay, bool keepalive, Plug *p);
Socket *sk_newlistener(const char *srcaddr, int port, Plug *plug,
bool local_host_only, int address_family);
static inline Plug *sk_plug(Socket *s, Plug *p)
{ return s->vt->plug(s, p); }
static inline void sk_close(Socket *s)
{ s->vt->close(s); }
static inline size_t sk_write(Socket *s, const void *data, size_t len)
{ return s->vt->write(s, data, len); }
static inline size_t sk_write_oob(Socket *s, const void *data, size_t len)
{ return s->vt->write_oob(s, data, len); }
static inline void sk_write_eof(Socket *s)
{ s->vt->write_eof(s); }
static inline void sk_flush(Socket *s)
{ s->vt->flush(s); }
static inline void plug_log(
Plug *p, int type, SockAddr *addr, int port, const char *msg, int code)
{ p->vt->log(p, type, addr, port, msg, code); }
static inline void plug_closing(
Plug *p, const char *msg, int code, bool calling_back)
{ p->vt->closing(p, msg, code, calling_back); }
static inline void plug_receive(Plug *p, int urg, const char *data, size_t len)
{ p->vt->receive(p, urg, data, len); }
static inline void plug_sent (Plug *p, size_t bufsize)
{ p->vt->sent(p, bufsize); }
static inline int plug_accepting(Plug *p, accept_fn_t cons, accept_ctx_t ctx)
{ return p->vt->accepting(p, cons, ctx); }
/*
* 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);
static inline const char *sk_socket_error(Socket *s)
{ return s->vt->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.
*/
static inline void sk_set_frozen(Socket *s, bool is_frozen)
{ s->vt->set_frozen(s, is_frozen); }
/*
* Return a structure giving some information about the other end of
* the socket. May be NULL, if nothing is available at all. If it is
* not NULL, then it is dynamically allocated, and should be freed by
* a call to sk_free_peer_info(). See below for the definition.
*/
static inline SocketPeerInfo *sk_peer_info(Socket *s)
{ return s->vt->peer_info(s); }
/*
* The structure returned from sk_peer_info, and a function to free
* one (in misc.c).
*/
struct SocketPeerInfo {
int addressfamily;
/*
* Text form of the IPv4 or IPv6 address of the other end of the
* socket, if available, in the standard text representation.
*/
const char *addr_text;
/*
* Binary form of the same address. Filled in if and only if
* addr_text is not NULL. You can tell which branch of the union
* is used by examining 'addressfamily'.
*/
union {
unsigned char ipv6[16];
unsigned char ipv4[4];
} addr_bin;
/*
* Remote port number, or -1 if not available.
*/
int port;
/*
* Free-form text suitable for putting in log messages. For IP
* sockets, repeats the address and port information from above.
* But it can be completely different, e.g. for Unix-domain
* sockets it gives information about the uid, gid and pid of the
* connecting process.
*/
const char *log_text;
};
void sk_free_peer_info(SocketPeerInfo *pi);
/*
* 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);
/*
* Trivial socket implementation which just stores an error. Found in
* errsock.c.
*/
Socket *new_error_socket_fmt(Plug *plug, const char *fmt, ...);
/*
* Trivial plug that does absolutely nothing. Found in nullplug.c.
*/
extern Plug *const nullplug;
/* ----------------------------------------------------------------------
* Functions defined outside the network code, which have to be
* declared in this header file rather than the main putty.h because
* they use types defined here.
*/
/*
* Exports from be_misc.c.
*/
void backend_socket_log(Seat *seat, LogContext *logctx,
int type, SockAddr *addr, int port,
const char *error_msg, int error_code, Conf *conf,
bool session_started);
typedef struct ProxyStderrBuf {
char buf[8192];
size_t size;
} ProxyStderrBuf;
void psb_init(ProxyStderrBuf *psb);
void log_proxy_stderr(
Plug *plug, ProxyStderrBuf *psb, const void *vdata, size_t len);
#endif