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putty-source/network.h

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/*
* 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);
int (*write) (Socket *s, const void *data, int len);
int (*write_oob) (Socket *s, const void *data, int len);
void (*write_eof) (Socket *s);
void (*flush) (Socket *s);
void (*set_frozen) (Socket *s, int 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, 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()) */
void (*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, 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, int privport,
int oobinline, int nodelay, int keepalive,
Plug *plug, Conf *conf);
Socket *new_listener(const char *srcaddr, int port, Plug *plug,
int local_host_only, Conf *conf, int addressfamily);
SockAddr *name_lookup(const char *host, int port, char **canonicalname,
Refactor the LogContext type. LogContext is now the owner of the logevent() function that back ends and so forth are constantly calling. Previously, logevent was owned by the Frontend, which would store the message into its list for the GUI Event Log dialog (or print it to standard error, or whatever) and then pass it _back_ to LogContext to write to the currently open log file. Now it's the other way round: LogContext gets the message from the back end first, writes it to its log file if it feels so inclined, and communicates it back to the front end. This means that lots of parts of the back end system no longer need to have a pointer to a full-on Frontend; the only thing they needed it for was logging, so now they just have a LogContext (which many of them had to have anyway, e.g. for logging SSH packets or session traffic). LogContext itself also doesn't get a full Frontend pointer any more: it now talks back to the front end via a little vtable of its own called LogPolicy, which contains the method that passes Event Log entries through, the old askappend() function that decides whether to truncate a pre-existing log file, and an emergency function for printing an especially prominent message if the log file can't be created. One minor nice effect of this is that console and GUI apps can implement that last function subtly differently, so that Unix console apps can write it with a plain \n instead of the \r\n (harmless but inelegant) that the old centralised implementation generated. One other consequence of this is that the LogContext has to be provided to backend_init() so that it's available to backends from the instant of creation, rather than being provided via a separate API call a couple of function calls later, because backends have typically started doing things that need logging (like making network connections) before the call to backend_provide_logctx. Fortunately, there's no case in the whole code base where we don't already have logctx by the time we make a backend (so I don't actually remember why I ever delayed providing one). So that shortens the backend API by one function, which is always nice. While I'm tidying up, I've also moved the printf-style logeventf() and the handy logevent_and_free() into logging.c, instead of having copies of them scattered around other places. This has also let me remove some stub functions from a couple of outlying applications like Pageant. Finally, I've removed the pointless "_tag" at the end of LogContext's official struct name.
2018-10-10 18:26:18 +00:00
Conf *conf, int addressfamily, LogContext *logctx,
const char *lookup_reason_for_logging);
int 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, 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_addr_needs_port(SockAddr *addr);
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(const char *srcaddr, int port, Plug *plug,
int local_host_only, int address_family);
#define sk_plug(s,p) (((s)->vt->plug) (s, p))
#define sk_close(s) (((s)->vt->close) (s))
#define sk_write(s,buf,len) (((s)->vt->write) (s, buf, len))
#define sk_write_oob(s,buf,len) (((s)->vt->write_oob) (s, buf, len))
#define sk_write_eof(s) (((s)->vt->write_eof) (s))
#define sk_flush(s) (((s)->vt->flush) (s))
#define plug_log(p,type,addr,port,msg,code) \
(((p)->vt->log) (p, type, addr, port, msg, code))
#define plug_closing(p,msg,code,callback) \
(((p)->vt->closing) (p, msg, code, callback))
#define plug_receive(p,urgent,buf,len) \
(((p)->vt->receive) (p, urgent, buf, len))
#define plug_sent(p,bufsize) \
(((p)->vt->sent) (p, bufsize))
#define plug_accepting(p, constructor, ctx) \
(((p)->vt->accepting)(p, constructor, 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);
#define sk_socket_error(s) (((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.
*/
#define sk_set_frozen(s, 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.
*/
#define sk_peer_info(s) (((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.
*/
New abstraction 'Seat', to pass to backends. This is a new vtable-based abstraction which is passed to a backend in place of Frontend, and it implements only the subset of the Frontend functions needed by a backend. (Many other Frontend functions still exist, notably the wide range of things called by terminal.c providing platform-independent operations on the GUI terminal window.) The purpose of making it a vtable is that this opens up the possibility of creating a backend as an internal implementation detail of some other activity, by providing just that one backend with a custom Seat that implements the methods differently. For example, this refactoring should make it feasible to directly implement an SSH proxy type, aka the 'jump host' feature supported by OpenSSH, aka 'open a secondary SSH session in MAINCHAN_DIRECT_TCP mode, and then expose the main channel of that as the Socket for the primary connection'. (Which of course you can already do by spawning 'plink -nc' as a separate proxy process, but this would permit it in the _same_ process without anything getting confused.) I've centralised a full set of stub methods in misc.c for the new abstraction, which allows me to get rid of several annoying stubs in the previous code. Also, while I'm here, I've moved a lot of duplicated modalfatalbox() type functions from application main program files into wincons.c / uxcons.c, which I think saves duplication overall. (A minor visible effect is that the prefixes on those console-based fatal error messages will now be more consistent between applications.)
2018-10-11 18:58:42 +00:00
void backend_socket_log(Seat *seat, LogContext *logctx,
Refactor the LogContext type. LogContext is now the owner of the logevent() function that back ends and so forth are constantly calling. Previously, logevent was owned by the Frontend, which would store the message into its list for the GUI Event Log dialog (or print it to standard error, or whatever) and then pass it _back_ to LogContext to write to the currently open log file. Now it's the other way round: LogContext gets the message from the back end first, writes it to its log file if it feels so inclined, and communicates it back to the front end. This means that lots of parts of the back end system no longer need to have a pointer to a full-on Frontend; the only thing they needed it for was logging, so now they just have a LogContext (which many of them had to have anyway, e.g. for logging SSH packets or session traffic). LogContext itself also doesn't get a full Frontend pointer any more: it now talks back to the front end via a little vtable of its own called LogPolicy, which contains the method that passes Event Log entries through, the old askappend() function that decides whether to truncate a pre-existing log file, and an emergency function for printing an especially prominent message if the log file can't be created. One minor nice effect of this is that console and GUI apps can implement that last function subtly differently, so that Unix console apps can write it with a plain \n instead of the \r\n (harmless but inelegant) that the old centralised implementation generated. One other consequence of this is that the LogContext has to be provided to backend_init() so that it's available to backends from the instant of creation, rather than being provided via a separate API call a couple of function calls later, because backends have typically started doing things that need logging (like making network connections) before the call to backend_provide_logctx. Fortunately, there's no case in the whole code base where we don't already have logctx by the time we make a backend (so I don't actually remember why I ever delayed providing one). So that shortens the backend API by one function, which is always nice. While I'm tidying up, I've also moved the printf-style logeventf() and the handy logevent_and_free() into logging.c, instead of having copies of them scattered around other places. This has also let me remove some stub functions from a couple of outlying applications like Pageant. Finally, I've removed the pointless "_tag" at the end of LogContext's official struct name.
2018-10-10 18:26:18 +00:00
int type, SockAddr *addr, int port,
const char *error_msg, int error_code, Conf *conf,
int session_started);
void log_proxy_stderr(Plug *plug, bufchain *buf, const void *vdata, int len);
#endif