зеркало из https://github.com/github/putty.git
637 строки
16 KiB
C
637 строки
16 KiB
C
/*
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* SSH port forwarding.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "putty.h"
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#include "ssh.h"
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#ifndef FALSE
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#define FALSE 0
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#endif
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#ifndef TRUE
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#define TRUE 1
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#endif
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struct PortForwarding {
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const struct plug_function_table *fn;
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/* the above variable absolutely *must* be the first in this structure */
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struct ssh_channel *c; /* channel structure held by ssh.c */
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void *backhandle; /* instance of SSH backend itself */
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/* Note that backhandle need not be filled in if c is non-NULL */
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Socket s;
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int throttled, throttle_override;
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int ready;
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/*
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* `dynamic' does double duty. It's set to 0 for an ordinary
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* forwarded port, and nonzero for SOCKS-style dynamic port
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* forwarding; but the nonzero values are also a state machine
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* tracking where the SOCKS exchange has got to.
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*/
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int dynamic;
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/*
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* `hostname' and `port' are the real hostname and port, once
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* we know what we're connecting to.
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*/
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char *hostname;
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int port;
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/*
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* `socksbuf' is the buffer we use to accumulate a SOCKS request.
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*/
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char *socksbuf;
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int sockslen, sockssize;
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/*
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* When doing dynamic port forwarding, we can receive
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* connection data before we are actually able to send it; so
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* we may have to temporarily hold some in a dynamically
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* allocated buffer here.
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*/
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void *buffer;
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int buflen;
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};
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struct PortListener {
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const struct plug_function_table *fn;
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/* the above variable absolutely *must* be the first in this structure */
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void *backhandle; /* instance of SSH backend itself */
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Socket s;
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/*
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* `dynamic' is set to 0 for an ordinary forwarded port, and
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* nonzero for SOCKS-style dynamic port forwarding.
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*/
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int dynamic;
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/*
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* `hostname' and `port' are the real hostname and port, for
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* ordinary forwardings.
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*/
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char *hostname;
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int port;
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};
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static struct PortForwarding *new_portfwd_state(void)
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{
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struct PortForwarding *pf = snew(struct PortForwarding);
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pf->hostname = NULL;
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pf->socksbuf = NULL;
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pf->sockslen = pf->sockssize = 0;
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pf->buffer = NULL;
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return pf;
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}
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static void free_portfwd_state(struct PortForwarding *pf)
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{
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if (!pf)
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return;
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sfree(pf->hostname);
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sfree(pf->socksbuf);
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sfree(pf->buffer);
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sfree(pf);
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}
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static struct PortListener *new_portlistener_state(void)
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{
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struct PortListener *pl = snew(struct PortListener);
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pl->hostname = NULL;
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return pl;
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}
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static void free_portlistener_state(struct PortListener *pl)
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{
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if (!pl)
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return;
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sfree(pl->hostname);
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sfree(pl);
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}
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static void pfd_log(Plug plug, 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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/* we have to dump these since we have no interface to logging.c */
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}
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static void pfl_log(Plug plug, 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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/* we have to dump these since we have no interface to logging.c */
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}
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static int pfd_closing(Plug plug, const char *error_msg, int error_code,
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int calling_back)
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{
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struct PortForwarding *pf = (struct PortForwarding *) plug;
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if (error_msg) {
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/*
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* Socket error. Slam the connection instantly shut.
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*/
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if (pf->c) {
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sshfwd_unclean_close(pf->c, error_msg);
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} else {
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/*
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* We might not have an SSH channel, if a socket error
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* occurred during SOCKS negotiation. If not, we must
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* clean ourself up without sshfwd_unclean_close's call
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* back to pfd_close.
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*/
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pfd_close(pf);
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}
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} else {
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/*
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* Ordinary EOF received on socket. Send an EOF on the SSH
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* channel.
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*/
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if (pf->c)
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sshfwd_write_eof(pf->c);
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}
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return 1;
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}
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static int pfl_closing(Plug plug, const char *error_msg, int error_code,
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int calling_back)
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{
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struct PortListener *pl = (struct PortListener *) plug;
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pfl_terminate(pl);
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return 1;
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}
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static int pfd_receive(Plug plug, int urgent, char *data, int len)
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{
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struct PortForwarding *pf = (struct PortForwarding *) plug;
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if (pf->dynamic) {
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while (len--) {
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if (pf->sockslen >= pf->sockssize) {
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pf->sockssize = pf->sockslen * 5 / 4 + 256;
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pf->socksbuf = sresize(pf->socksbuf, pf->sockssize, char);
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}
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pf->socksbuf[pf->sockslen++] = *data++;
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/*
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* Now check what's in the buffer to see if it's a
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* valid and complete message in the SOCKS exchange.
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*/
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if ((pf->dynamic == 1 || (pf->dynamic >> 12) == 4) &&
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pf->socksbuf[0] == 4) {
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/*
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* SOCKS 4.
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*/
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if (pf->dynamic == 1)
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pf->dynamic = 0x4000;
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if (pf->sockslen < 2)
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continue; /* don't have command code yet */
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if (pf->socksbuf[1] != 1) {
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/* Not CONNECT. */
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/* Send back a SOCKS 4 error before closing. */
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char data[8];
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memset(data, 0, sizeof(data));
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data[1] = 91; /* generic `request rejected' */
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sk_write(pf->s, data, 8);
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pfd_close(pf);
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return 1;
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}
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if (pf->sockslen <= 8)
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continue; /* haven't started user/hostname */
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if (pf->socksbuf[pf->sockslen-1] != 0)
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continue; /* haven't _finished_ user/hostname */
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/*
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* Now we have a full SOCKS 4 request. Check it to
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* see if it's a SOCKS 4A request.
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*/
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if (pf->socksbuf[4] == 0 && pf->socksbuf[5] == 0 &&
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pf->socksbuf[6] == 0 && pf->socksbuf[7] != 0) {
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/*
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* It's SOCKS 4A. So if we haven't yet
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* collected the host name, we should continue
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* waiting for data in order to do so; if we
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* have, we can go ahead.
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*/
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int len;
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if (pf->dynamic == 0x4000) {
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pf->dynamic = 0x4001;
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pf->sockslen = 8; /* reset buffer to overwrite name */
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continue;
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}
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pf->socksbuf[0] = 0; /* reply version code */
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pf->socksbuf[1] = 90; /* request granted */
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sk_write(pf->s, pf->socksbuf, 8);
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len = pf->sockslen - 8;
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pf->port = GET_16BIT_MSB_FIRST(pf->socksbuf+2);
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pf->hostname = snewn(len+1, char);
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pf->hostname[len] = '\0';
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memcpy(pf->hostname, pf->socksbuf + 8, len);
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goto connect;
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} else {
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/*
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* It's SOCKS 4, which means we should format
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* the IP address into the hostname string and
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* then just go.
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*/
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pf->socksbuf[0] = 0; /* reply version code */
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pf->socksbuf[1] = 90; /* request granted */
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sk_write(pf->s, pf->socksbuf, 8);
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pf->port = GET_16BIT_MSB_FIRST(pf->socksbuf+2);
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pf->hostname = dupprintf("%d.%d.%d.%d",
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(unsigned char)pf->socksbuf[4],
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(unsigned char)pf->socksbuf[5],
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(unsigned char)pf->socksbuf[6],
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(unsigned char)pf->socksbuf[7]);
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goto connect;
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}
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}
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if ((pf->dynamic == 1 || (pf->dynamic >> 12) == 5) &&
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pf->socksbuf[0] == 5) {
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/*
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* SOCKS 5.
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*/
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if (pf->dynamic == 1)
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pf->dynamic = 0x5000;
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if (pf->dynamic == 0x5000) {
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int i, method;
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char data[2];
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/*
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* We're receiving a set of method identifiers.
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*/
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if (pf->sockslen < 2)
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continue; /* no method count yet */
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if (pf->sockslen < 2 + (unsigned char)pf->socksbuf[1])
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continue; /* no methods yet */
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method = 0xFF; /* invalid */
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for (i = 0; i < (unsigned char)pf->socksbuf[1]; i++)
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if (pf->socksbuf[2+i] == 0) {
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method = 0;/* no auth */
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break;
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}
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data[0] = 5;
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data[1] = method;
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sk_write(pf->s, data, 2);
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pf->dynamic = 0x5001;
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pf->sockslen = 0; /* re-empty the buffer */
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continue;
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}
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if (pf->dynamic == 0x5001) {
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/*
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* We're receiving a SOCKS request.
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*/
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unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
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int atype, alen = 0;
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/*
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* Pre-fill reply packet.
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* In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
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* (atyp=1) in the reply; if we succeed, we don't know
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* the right answers, and if we fail, they should be
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* ignored.
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*/
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memset(reply, 0, lenof(reply));
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reply[0] = 5; /* VER */
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reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
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if (pf->sockslen < 6) continue;
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atype = (unsigned char)pf->socksbuf[3];
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if (atype == 1) /* IPv4 address */
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alen = 4;
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if (atype == 4) /* IPv6 address */
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alen = 16;
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if (atype == 3) /* domain name has leading length */
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alen = 1 + (unsigned char)pf->socksbuf[4];
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if (pf->sockslen < 6 + alen) continue;
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if (pf->socksbuf[1] != 1 || pf->socksbuf[2] != 0) {
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/* Not CONNECT or reserved field nonzero - error */
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reply[1] = 1; /* generic failure */
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sk_write(pf->s, (char *) reply, lenof(reply));
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pfd_close(pf);
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return 1;
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}
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/*
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* Now we have a viable connect request. Switch
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* on atype.
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*/
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pf->port = GET_16BIT_MSB_FIRST(pf->socksbuf+4+alen);
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if (atype == 1) {
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/* REP=0 (success) already */
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sk_write(pf->s, (char *) reply, lenof(reply));
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pf->hostname = dupprintf("%d.%d.%d.%d",
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(unsigned char)pf->socksbuf[4],
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(unsigned char)pf->socksbuf[5],
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(unsigned char)pf->socksbuf[6],
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(unsigned char)pf->socksbuf[7]);
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goto connect;
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} else if (atype == 3) {
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/* REP=0 (success) already */
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sk_write(pf->s, (char *) reply, lenof(reply));
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pf->hostname = snewn(alen, char);
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pf->hostname[alen-1] = '\0';
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memcpy(pf->hostname, pf->socksbuf + 5, alen-1);
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goto connect;
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} else {
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/*
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* Unknown address type. (FIXME: support IPv6!)
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*/
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reply[1] = 8; /* atype not supported */
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sk_write(pf->s, (char *) reply, lenof(reply));
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pfd_close(pf);
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return 1;
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}
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}
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}
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/*
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* If we get here without either having done `continue'
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* or `goto connect', it must be because there is no
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* sensible interpretation of what's in our buffer. So
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* close the connection rudely.
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*/
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pfd_close(pf);
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return 1;
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}
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return 1;
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/*
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* We come here when we're ready to make an actual
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* connection.
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*/
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connect:
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sfree(pf->socksbuf);
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pf->socksbuf = NULL;
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/*
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* Freeze the socket until the SSH server confirms the
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* connection.
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*/
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sk_set_frozen(pf->s, 1);
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pf->c = new_sock_channel(pf->backhandle, pf);
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if (pf->c == NULL) {
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pfd_close(pf);
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return 1;
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} else {
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/* asks to forward to the specified host/port for this */
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ssh_send_port_open(pf->c, pf->hostname, pf->port, "forwarding");
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}
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pf->dynamic = 0;
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/*
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* If there's any data remaining in our current buffer,
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* save it to be sent on pfd_confirm().
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*/
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if (len > 0) {
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pf->buffer = snewn(len, char);
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memcpy(pf->buffer, data, len);
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pf->buflen = len;
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}
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}
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if (pf->ready) {
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if (sshfwd_write(pf->c, data, len) > 0) {
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pf->throttled = 1;
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sk_set_frozen(pf->s, 1);
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}
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}
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return 1;
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}
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static void pfd_sent(Plug plug, int bufsize)
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{
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struct PortForwarding *pf = (struct PortForwarding *) plug;
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if (pf->c)
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sshfwd_unthrottle(pf->c, bufsize);
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}
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/*
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* Called when receiving a PORT OPEN from the server to make a
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* connection to a destination host.
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*
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* On success, returns NULL and fills in *pf_ret. On error, returns a
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* dynamically allocated error message string.
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*/
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char *pfd_connect(struct PortForwarding **pf_ret, char *hostname,int port,
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void *c, Conf *conf, int addressfamily)
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{
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static const struct plug_function_table fn_table = {
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pfd_log,
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pfd_closing,
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pfd_receive,
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pfd_sent,
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NULL
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};
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SockAddr addr;
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const char *err;
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char *dummy_realhost;
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struct PortForwarding *pf;
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/*
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* Try to find host.
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*/
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addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily);
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if ((err = sk_addr_error(addr)) != NULL) {
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char *err_ret = dupstr(err);
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sk_addr_free(addr);
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sfree(dummy_realhost);
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return err_ret;
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}
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/*
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* Open socket.
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*/
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pf = *pf_ret = new_portfwd_state();
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pf->fn = &fn_table;
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pf->throttled = pf->throttle_override = 0;
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pf->ready = 1;
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pf->c = c;
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pf->backhandle = NULL; /* we shouldn't need this */
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pf->dynamic = 0;
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pf->s = new_connection(addr, dummy_realhost, port,
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0, 1, 0, 0, (Plug) pf, conf);
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sfree(dummy_realhost);
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if ((err = sk_socket_error(pf->s)) != NULL) {
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char *err_ret = dupstr(err);
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sk_close(pf->s);
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free_portfwd_state(pf);
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*pf_ret = NULL;
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return err_ret;
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}
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return NULL;
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}
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/*
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called when someone connects to the local port
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*/
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static int pfl_accepting(Plug p, accept_fn_t constructor, accept_ctx_t ctx)
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{
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static const struct plug_function_table fn_table = {
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pfd_log,
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pfd_closing,
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pfd_receive,
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pfd_sent,
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NULL
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};
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struct PortForwarding *pf;
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struct PortListener *pl;
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Socket s;
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const char *err;
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pl = (struct PortListener *)p;
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pf = new_portfwd_state();
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pf->fn = &fn_table;
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pf->c = NULL;
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pf->backhandle = pl->backhandle;
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pf->s = s = constructor(ctx, (Plug) pf);
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if ((err = sk_socket_error(s)) != NULL) {
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free_portfwd_state(pf);
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return err != NULL;
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}
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pf->throttled = pf->throttle_override = 0;
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pf->ready = 0;
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if (pl->dynamic) {
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pf->dynamic = 1;
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pf->port = 0; /* "hostname" buffer is so far empty */
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sk_set_frozen(s, 0); /* we want to receive SOCKS _now_! */
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} else {
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pf->dynamic = 0;
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pf->hostname = dupstr(pl->hostname);
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pf->port = pl->port;
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pf->c = new_sock_channel(pl->backhandle, pf);
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if (pf->c == NULL) {
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free_portfwd_state(pf);
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return 1;
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} else {
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/* asks to forward to the specified host/port for this */
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ssh_send_port_open(pf->c, pf->hostname, pf->port, "forwarding");
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}
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}
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return 0;
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}
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/*
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* Add a new port-forwarding listener from srcaddr:port -> desthost:destport.
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*
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* On success, returns NULL and fills in *pl_ret. On error, returns a
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* dynamically allocated error message string.
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*/
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char *pfl_listen(char *desthost, int destport, char *srcaddr,
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int port, void *backhandle, Conf *conf,
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struct PortListener **pl_ret, int address_family)
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{
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static const struct plug_function_table fn_table = {
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|
pfl_log,
|
|
pfl_closing,
|
|
NULL, /* recv */
|
|
NULL, /* send */
|
|
pfl_accepting
|
|
};
|
|
|
|
const char *err;
|
|
struct PortListener *pl;
|
|
|
|
/*
|
|
* Open socket.
|
|
*/
|
|
pl = *pl_ret = new_portlistener_state();
|
|
pl->fn = &fn_table;
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|
if (desthost) {
|
|
pl->hostname = dupstr(desthost);
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|
pl->port = destport;
|
|
pl->dynamic = 0;
|
|
} else
|
|
pl->dynamic = 1;
|
|
pl->backhandle = backhandle;
|
|
|
|
pl->s = new_listener(srcaddr, port, (Plug) pl,
|
|
!conf_get_int(conf, CONF_lport_acceptall),
|
|
conf, address_family);
|
|
if ((err = sk_socket_error(pl->s)) != NULL) {
|
|
char *err_ret = dupstr(err);
|
|
sk_close(pl->s);
|
|
free_portlistener_state(pl);
|
|
*pl_ret = NULL;
|
|
return err_ret;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
void pfd_close(struct PortForwarding *pf)
|
|
{
|
|
if (!pf)
|
|
return;
|
|
|
|
sk_close(pf->s);
|
|
free_portfwd_state(pf);
|
|
}
|
|
|
|
/*
|
|
* Terminate a listener.
|
|
*/
|
|
void pfl_terminate(struct PortListener *pl)
|
|
{
|
|
if (!pl)
|
|
return;
|
|
|
|
sk_close(pl->s);
|
|
free_portlistener_state(pl);
|
|
}
|
|
|
|
void pfd_unthrottle(struct PortForwarding *pf)
|
|
{
|
|
if (!pf)
|
|
return;
|
|
|
|
pf->throttled = 0;
|
|
sk_set_frozen(pf->s, pf->throttled || pf->throttle_override);
|
|
}
|
|
|
|
void pfd_override_throttle(struct PortForwarding *pf, int enable)
|
|
{
|
|
if (!pf)
|
|
return;
|
|
|
|
pf->throttle_override = enable;
|
|
sk_set_frozen(pf->s, pf->throttled || pf->throttle_override);
|
|
}
|
|
|
|
/*
|
|
* Called to send data down the raw connection.
|
|
*/
|
|
int pfd_send(struct PortForwarding *pf, char *data, int len)
|
|
{
|
|
if (pf == NULL)
|
|
return 0;
|
|
return sk_write(pf->s, data, len);
|
|
}
|
|
|
|
void pfd_send_eof(struct PortForwarding *pf)
|
|
{
|
|
sk_write_eof(pf->s);
|
|
}
|
|
|
|
void pfd_confirm(struct PortForwarding *pf)
|
|
{
|
|
if (pf == NULL)
|
|
return;
|
|
|
|
pf->ready = 1;
|
|
sk_set_frozen(pf->s, 0);
|
|
sk_write(pf->s, NULL, 0);
|
|
if (pf->buffer) {
|
|
sshfwd_write(pf->c, pf->buffer, pf->buflen);
|
|
sfree(pf->buffer);
|
|
pf->buffer = NULL;
|
|
}
|
|
}
|