зеркало из https://github.com/github/putty.git
286 строки
11 KiB
C
286 строки
11 KiB
C
/*
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* Networking abstraction in PuTTY.
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*
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* The way this works is: a back end can choose to open any number
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* of sockets - including zero, which might be necessary in some.
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* It can register a bunch of callbacks (most notably for when
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* data is received) for each socket, and it can call the networking
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* abstraction to send data without having to worry about blocking.
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* The stuff behind the abstraction takes care of selects and
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* nonblocking writes and all that sort of painful gubbins.
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*/
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#ifndef PUTTY_NETWORK_H
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#define PUTTY_NETWORK_H
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#include "defs.h"
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typedef struct SocketVtable SocketVtable;
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typedef struct PlugVtable PlugVtable;
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struct Socket {
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const struct SocketVtable *vt;
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};
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struct SocketVtable {
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Plug *(*plug) (Socket *s, Plug *p);
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/* use a different plug (return the old one) */
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/* if p is NULL, it doesn't change the plug */
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/* but it does return the one it's using */
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void (*close) (Socket *s);
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size_t (*write) (Socket *s, const void *data, size_t len);
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size_t (*write_oob) (Socket *s, const void *data, size_t len);
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void (*write_eof) (Socket *s);
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void (*flush) (Socket *s);
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void (*set_frozen) (Socket *s, bool is_frozen);
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/* ignored by tcp, but vital for ssl */
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const char *(*socket_error) (Socket *s);
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SocketPeerInfo *(*peer_info) (Socket *s);
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};
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typedef union { void *p; int i; } accept_ctx_t;
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typedef Socket *(*accept_fn_t)(accept_ctx_t ctx, Plug *plug);
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struct Plug {
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const struct PlugVtable *vt;
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};
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struct PlugVtable {
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void (*log)(Plug *p, int type, SockAddr *addr, int port,
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const char *error_msg, int error_code);
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/*
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* Passes the client progress reports on the process of setting
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* up the connection.
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*
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* - type==0 means we are about to try to connect to address
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* `addr' (error_msg and error_code are ignored)
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* - type==1 means we have failed to connect to address `addr'
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* (error_msg and error_code are supplied). This is not a
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* fatal error - we may well have other candidate addresses
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* to fall back to. When it _is_ fatal, the closing()
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* function will be called.
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* - type==2 means that error_msg contains a line of generic
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* logging information about setting up the connection. This
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* will typically be a wodge of standard-error output from a
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* proxy command, so the receiver should probably prefix it to
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* indicate this.
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*/
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void (*closing)
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(Plug *p, const char *error_msg, int error_code, bool calling_back);
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/* error_msg is NULL iff it is not an error (ie it closed normally) */
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/* calling_back != 0 iff there is a Plug function */
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/* currently running (would cure the fixme in try_send()) */
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void (*receive) (Plug *p, int urgent, const char *data, size_t len);
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/*
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* - urgent==0. `data' points to `len' bytes of perfectly
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* ordinary data.
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*
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* - urgent==1. `data' points to `len' bytes of data,
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* which were read from before an Urgent pointer.
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*
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* - urgent==2. `data' points to `len' bytes of data,
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* the first of which was the one at the Urgent mark.
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*/
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void (*sent) (Plug *p, size_t bufsize);
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/*
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* The `sent' function is called when the pending send backlog
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* on a socket is cleared or partially cleared. The new backlog
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* size is passed in the `bufsize' parameter.
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*/
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int (*accepting)(Plug *p, accept_fn_t constructor, accept_ctx_t ctx);
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/*
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* `accepting' is called only on listener-type sockets, and is
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* passed a constructor function+context that will create a fresh
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* Socket describing the connection. It returns nonzero if it
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* doesn't want the connection for some reason, or 0 on success.
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*/
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};
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/* proxy indirection layer */
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/* NB, control of 'addr' is passed via new_connection, which takes
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* responsibility for freeing it */
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Socket *new_connection(SockAddr *addr, const char *hostname,
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int port, bool privport,
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bool oobinline, bool nodelay, bool keepalive,
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Plug *plug, Conf *conf);
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Socket *new_listener(const char *srcaddr, int port, Plug *plug,
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bool local_host_only, Conf *conf, int addressfamily);
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SockAddr *name_lookup(const char *host, int port, char **canonicalname,
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Conf *conf, int addressfamily, LogContext *logctx,
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const char *lookup_reason_for_logging);
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bool proxy_for_destination (SockAddr *addr, const char *hostname, int port,
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Conf *conf);
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/* platform-dependent callback from new_connection() */
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/* (same caveat about addr as new_connection()) */
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Socket *platform_new_connection(SockAddr *addr, const char *hostname,
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int port, bool privport,
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bool oobinline, bool nodelay, bool keepalive,
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Plug *plug, Conf *conf);
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/* socket functions */
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void sk_init(void); /* called once at program startup */
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void sk_cleanup(void); /* called just before program exit */
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SockAddr *sk_namelookup(const char *host, char **canonicalname, int address_family);
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SockAddr *sk_nonamelookup(const char *host);
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void sk_getaddr(SockAddr *addr, char *buf, int buflen);
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bool sk_addr_needs_port(SockAddr *addr);
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bool sk_hostname_is_local(const char *name);
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bool sk_address_is_local(SockAddr *addr);
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bool sk_address_is_special_local(SockAddr *addr);
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int sk_addrtype(SockAddr *addr);
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void sk_addrcopy(SockAddr *addr, char *buf);
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void sk_addr_free(SockAddr *addr);
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/* sk_addr_dup generates another SockAddr which contains the same data
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* as the original one and can be freed independently. May not actually
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* physically _duplicate_ it: incrementing a reference count so that
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* one more free is required before it disappears is an acceptable
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* implementation. */
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SockAddr *sk_addr_dup(SockAddr *addr);
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/* NB, control of 'addr' is passed via sk_new, which takes responsibility
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* for freeing it, as for new_connection() */
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Socket *sk_new(SockAddr *addr, int port, bool privport, bool oobinline,
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bool nodelay, bool keepalive, Plug *p);
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Socket *sk_newlistener(const char *srcaddr, int port, Plug *plug,
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bool local_host_only, int address_family);
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#define sk_plug(s,p) (((s)->vt->plug) (s, p))
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#define sk_close(s) (((s)->vt->close) (s))
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#define sk_write(s,buf,len) (((s)->vt->write) (s, buf, len))
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#define sk_write_oob(s,buf,len) (((s)->vt->write_oob) (s, buf, len))
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#define sk_write_eof(s) (((s)->vt->write_eof) (s))
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#define sk_flush(s) (((s)->vt->flush) (s))
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#define plug_log(p,type,addr,port,msg,code) \
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(((p)->vt->log) (p, type, addr, port, msg, code))
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#define plug_closing(p,msg,code,callback) \
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(((p)->vt->closing) (p, msg, code, callback))
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#define plug_receive(p,urgent,buf,len) \
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(((p)->vt->receive) (p, urgent, buf, len))
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#define plug_sent(p,bufsize) \
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(((p)->vt->sent) (p, bufsize))
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#define plug_accepting(p, constructor, ctx) \
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(((p)->vt->accepting)(p, constructor, ctx))
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/*
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* Special error values are returned from sk_namelookup and sk_new
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* if there's a problem. These functions extract an error message,
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* or return NULL if there's no problem.
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*/
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const char *sk_addr_error(SockAddr *addr);
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#define sk_socket_error(s) (((s)->vt->socket_error) (s))
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/*
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* Set the `frozen' flag on a socket. A frozen socket is one in
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* which all READABLE notifications are ignored, so that data is
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* not accepted from the peer until the socket is unfrozen. This
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* exists for two purposes:
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*
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* - Port forwarding: when a local listening port receives a
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* connection, we do not want to receive data from the new
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* socket until we have somewhere to send it. Hence, we freeze
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* the socket until its associated SSH channel is ready; then we
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* unfreeze it and pending data is delivered.
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*
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* - Socket buffering: if an SSH channel (or the whole connection)
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* backs up or presents a zero window, we must freeze the
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* associated local socket in order to avoid unbounded buffer
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* growth.
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*/
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#define sk_set_frozen(s, is_frozen) (((s)->vt->set_frozen) (s, is_frozen))
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/*
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* Return a structure giving some information about the other end of
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* the socket. May be NULL, if nothing is available at all. If it is
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* not NULL, then it is dynamically allocated, and should be freed by
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* a call to sk_free_peer_info(). See below for the definition.
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*/
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#define sk_peer_info(s) (((s)->vt->peer_info) (s))
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/*
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* The structure returned from sk_peer_info, and a function to free
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* one (in misc.c).
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*/
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struct SocketPeerInfo {
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int addressfamily;
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/*
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* Text form of the IPv4 or IPv6 address of the other end of the
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* socket, if available, in the standard text representation.
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*/
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const char *addr_text;
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/*
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* Binary form of the same address. Filled in if and only if
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* addr_text is not NULL. You can tell which branch of the union
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* is used by examining 'addressfamily'.
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*/
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union {
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unsigned char ipv6[16];
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unsigned char ipv4[4];
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} addr_bin;
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/*
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* Remote port number, or -1 if not available.
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*/
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int port;
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/*
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* Free-form text suitable for putting in log messages. For IP
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* sockets, repeats the address and port information from above.
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* But it can be completely different, e.g. for Unix-domain
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* sockets it gives information about the uid, gid and pid of the
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* connecting process.
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*/
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const char *log_text;
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};
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void sk_free_peer_info(SocketPeerInfo *pi);
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/*
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* Simple wrapper on getservbyname(), needed by ssh.c. Returns the
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* port number, in host byte order (suitable for printf and so on).
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* Returns 0 on failure. Any platform not supporting getservbyname
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* can just return 0 - this function is not required to handle
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* numeric port specifications.
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*/
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int net_service_lookup(char *service);
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/*
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* Look up the local hostname; return value needs freeing.
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* May return NULL.
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*/
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char *get_hostname(void);
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/*
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* Trivial socket implementation which just stores an error. Found in
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* errsock.c.
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*/
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Socket *new_error_socket_fmt(Plug *plug, const char *fmt, ...);
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/*
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* Trivial plug that does absolutely nothing. Found in nullplug.c.
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*/
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extern Plug *const nullplug;
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/* ----------------------------------------------------------------------
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* Functions defined outside the network code, which have to be
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* declared in this header file rather than the main putty.h because
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* they use types defined here.
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*/
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/*
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* Exports from be_misc.c.
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*/
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void backend_socket_log(Seat *seat, LogContext *logctx,
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int type, SockAddr *addr, int port,
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const char *error_msg, int error_code, Conf *conf,
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bool session_started);
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void log_proxy_stderr(
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Plug *plug, bufchain *buf, const void *vdata, size_t len);
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#endif
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