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|
/*
* Network proxy abstraction in PuTTY
*
* A proxy layer, if necessary, wedges itself between the network
* code and the higher level backend.
*/
#include <assert.h>
#include <ctype.h>
#include <string.h>
#include "putty.h"
#include "network.h"
#include "proxy.h"
#define do_proxy_dns(conf) \
(conf_get_int(conf, CONF_proxy_dns) == FORCE_ON || \
(conf_get_int(conf, CONF_proxy_dns) == AUTO && \
conf_get_int(conf, CONF_proxy_type) != PROXY_SOCKS4))
static void proxy_negotiator_cleanup(ProxySocket *ps)
{
if (ps->pn) {
proxy_negotiator_free(ps->pn);
ps->pn = NULL;
}
if (ps->clientseat) {
interactor_return_seat(ps->clientitr);
ps->clientitr = NULL;
ps->clientseat = NULL;
}
}
/*
* Call this when proxy negotiation is complete, so that this
* socket can begin working normally.
*/
static void proxy_activate(ProxySocket *ps)
{
size_t output_before, output_after;
proxy_negotiator_cleanup(ps);
plug_log(ps->plug, PLUGLOG_CONNECT_SUCCESS, NULL, 0, NULL, 0);
/* we want to ignore new receive events until we have sent
* all of our buffered receive data.
*/
sk_set_frozen(ps->sub_socket, true);
/* how many bytes of output have we buffered? */
output_before = bufchain_size(&ps->pending_oob_output_data) +
bufchain_size(&ps->pending_output_data);
/* and keep track of how many bytes do not get sent. */
output_after = 0;
/* send buffered OOB writes */
while (bufchain_size(&ps->pending_oob_output_data) > 0) {
ptrlen data = bufchain_prefix(&ps->pending_oob_output_data);
output_after += sk_write_oob(ps->sub_socket, data.ptr, data.len);
bufchain_consume(&ps->pending_oob_output_data, data.len);
}
/* send buffered normal writes */
while (bufchain_size(&ps->pending_output_data) > 0) {
ptrlen data = bufchain_prefix(&ps->pending_output_data);
output_after += sk_write(ps->sub_socket, data.ptr, data.len);
bufchain_consume(&ps->pending_output_data, data.len);
}
/* if we managed to send any data, let the higher levels know. */
if (output_after < output_before)
plug_sent(ps->plug, output_after);
/* if we have a pending EOF to send, send it */
if (ps->pending_eof) sk_write_eof(ps->sub_socket);
/* if the backend wanted the socket unfrozen, try to unfreeze.
* our set_frozen handler will flush buffered receive data before
* unfreezing the actual underlying socket.
*/
if (!ps->freeze)
sk_set_frozen(&ps->sock, false);
}
/* basic proxy socket functions */
static Plug *sk_proxy_plug (Socket *s, Plug *p)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
Plug *ret = ps->plug;
if (p)
ps->plug = p;
return ret;
}
static void sk_proxy_close (Socket *s)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
sk_close(ps->sub_socket);
sk_addr_free(ps->proxy_addr);
sk_addr_free(ps->remote_addr);
proxy_negotiator_cleanup(ps);
bufchain_clear(&ps->output_from_negotiator);
sfree(ps);
}
static size_t sk_proxy_write (Socket *s, const void *data, size_t len)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
if (ps->pn) {
bufchain_add(&ps->pending_output_data, data, len);
return bufchain_size(&ps->pending_output_data);
}
return sk_write(ps->sub_socket, data, len);
}
static size_t sk_proxy_write_oob (Socket *s, const void *data, size_t len)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
if (ps->pn) {
bufchain_clear(&ps->pending_output_data);
bufchain_clear(&ps->pending_oob_output_data);
bufchain_add(&ps->pending_oob_output_data, data, len);
return len;
}
return sk_write_oob(ps->sub_socket, data, len);
}
static void sk_proxy_write_eof (Socket *s)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
if (ps->pn) {
ps->pending_eof = true;
return;
}
sk_write_eof(ps->sub_socket);
}
static void sk_proxy_set_frozen (Socket *s, bool is_frozen)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
if (ps->pn) {
ps->freeze = is_frozen;
return;
}
/* handle any remaining buffered recv data first */
if (bufchain_size(&ps->pending_input_data) > 0) {
ps->freeze = is_frozen;
/* loop while we still have buffered data, and while we are
* unfrozen. the plug_receive call in the loop could result
* in a call back into this function refreezing the socket,
* so we have to check each time.
*/
while (!ps->freeze && bufchain_size(&ps->pending_input_data) > 0) {
char databuf[512];
ptrlen data = bufchain_prefix(&ps->pending_input_data);
if (data.len > lenof(databuf))
data.len = lenof(databuf);
memcpy(databuf, data.ptr, data.len);
bufchain_consume(&ps->pending_input_data, data.len);
plug_receive(ps->plug, 0, databuf, data.len);
}
/* if we're still frozen, we'll have to wait for another
* call from the backend to finish unbuffering the data.
*/
if (ps->freeze) return;
}
sk_set_frozen(ps->sub_socket, is_frozen);
}
static const char *sk_proxy_socket_error (Socket *s)
{
ProxySocket *ps = container_of(s, ProxySocket, sock);
if (ps->error != NULL || ps->sub_socket == NULL) {
return ps->error;
}
return sk_socket_error(ps->sub_socket);
}
/* basic proxy plug functions */
static void plug_proxy_log(Plug *plug, PlugLogType type, SockAddr *addr,
int port, const char *error_msg, int error_code)
{
ProxySocket *ps = container_of(plug, ProxySocket, plugimpl);
plug_log(ps->plug, type, addr, port, error_msg, error_code);
}
static void plug_proxy_closing(Plug *p, PlugCloseType type,
const char *error_msg)
{
ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
proxy_negotiator_cleanup(ps);
plug_closing(ps->plug, type, error_msg);
}
static void proxy_negotiate(ProxySocket *ps)
{
assert(ps->pn);
proxy_negotiator_process_queue(ps->pn);
if (ps->pn->error) {
char *err = dupprintf("Proxy error: %s", ps->pn->error);
sfree(ps->pn->error);
proxy_negotiator_cleanup(ps);
plug_closing_error(ps->plug, err);
sfree(err);
return;
} else if (ps->pn->aborted) {
proxy_negotiator_cleanup(ps);
plug_closing_user_abort(ps->plug);
return;
}
if (ps->pn->reconnect) {
sk_close(ps->sub_socket);
SockAddr *proxy_addr = sk_addr_dup(ps->proxy_addr);
ps->sub_socket = sk_new(proxy_addr, ps->proxy_port,
ps->proxy_privport, ps->proxy_oobinline,
ps->proxy_nodelay, ps->proxy_keepalive,
&ps->plugimpl);
ps->pn->reconnect = false;
/* If the negotiator has asked us to reconnect, they are
* expecting that on the next call their input queue will
* consist entirely of data from the _new_ connection, without
* any remaining data buffered from the old one. (If they'd
* wanted the latter, they could have read it out of the input
* queue before asking us to close the connection.) */
bufchain_clear(&ps->pending_input_data);
}
while (bufchain_size(&ps->output_from_negotiator)) {
ptrlen data = bufchain_prefix(&ps->output_from_negotiator);
sk_write(ps->sub_socket, data.ptr, data.len);
bufchain_consume(&ps->output_from_negotiator, data.len);
}
if (ps->pn->done)
proxy_activate(ps);
}
static void plug_proxy_receive(
Plug *p, int urgent, const char *data, size_t len)
{
ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
if (ps->pn) {
/* we will lose the urgentness of this data, but since most,
* if not all, of this data will be consumed by the negotiation
* process, hopefully it won't affect the protocol above us
*/
bufchain_add(&ps->pending_input_data, data, len);
proxy_negotiate(ps);
} else {
plug_receive(ps->plug, urgent, data, len);
}
}
static void plug_proxy_sent (Plug *p, size_t bufsize)
{
ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
if (ps->pn)
return;
plug_sent(ps->plug, bufsize);
}
static int plug_proxy_accepting(Plug *p,
accept_fn_t constructor, accept_ctx_t ctx)
{
unreachable("ProxySockets never create listening Sockets");
}
/*
* This function can accept a NULL pointer as `addr', in which case
* it will only check the host name.
*/
static bool proxy_for_destination(SockAddr *addr, const char *hostname,
int port, Conf *conf)
{
int s = 0, e = 0;
char hostip[64];
int hostip_len, hostname_len;
const char *exclude_list;
/*
* Special local connections such as Unix-domain sockets
* unconditionally cannot be proxied, even in proxy-localhost
* mode. There just isn't any way to ask any known proxy type for
* them.
*/
if (addr && sk_address_is_special_local(addr))
return false; /* do not proxy */
/*
* Check the host name and IP against the hard-coded
* representations of `localhost'.
*/
if (!conf_get_bool(conf, CONF_even_proxy_localhost) &&
(sk_hostname_is_local(hostname) ||
(addr && sk_address_is_local(addr))))
return false; /* do not proxy */
/* we want a string representation of the IP address for comparisons */
if (addr) {
sk_getaddr(addr, hostip, 64);
hostip_len = strlen(hostip);
} else
hostip_len = 0; /* placate gcc; shouldn't be required */
hostname_len = strlen(hostname);
exclude_list = conf_get_str(conf, CONF_proxy_exclude_list);
/* now parse the exclude list, and see if either our IP
* or hostname matches anything in it.
*/
while (exclude_list[s]) {
while (exclude_list[s] &&
(isspace((unsigned char)exclude_list[s]) ||
exclude_list[s] == ',')) s++;
if (!exclude_list[s]) break;
e = s;
while (exclude_list[e] &&
(isalnum((unsigned char)exclude_list[e]) ||
exclude_list[e] == '-' ||
exclude_list[e] == '.' ||
exclude_list[e] == '*')) e++;
if (exclude_list[s] == '*') {
/* wildcard at beginning of entry */
if ((addr && strnicmp(hostip + hostip_len - (e - s - 1),
exclude_list + s + 1, e - s - 1) == 0) ||
strnicmp(hostname + hostname_len - (e - s - 1),
exclude_list + s + 1, e - s - 1) == 0) {
/* IP/hostname range excluded. do not use proxy. */
return false;
}
} else if (exclude_list[e-1] == '*') {
/* wildcard at end of entry */
if ((addr && strnicmp(hostip, exclude_list + s, e - s - 1) == 0) ||
strnicmp(hostname, exclude_list + s, e - s - 1) == 0) {
/* IP/hostname range excluded. do not use proxy. */
return false;
}
} else {
/* no wildcard at either end, so let's try an absolute
* match (ie. a specific IP)
*/
if (addr && strnicmp(hostip, exclude_list + s, e - s) == 0)
return false; /* IP/hostname excluded. do not use proxy. */
if (strnicmp(hostname, exclude_list + s, e - s) == 0)
return false; /* IP/hostname excluded. do not use proxy. */
}
s = e;
/* Make sure we really have reached the next comma or end-of-string */
while (exclude_list[s] &&
!isspace((unsigned char)exclude_list[s]) &&
exclude_list[s] != ',') s++;
}
/* no matches in the exclude list, so use the proxy */
return true;
}
static char *dns_log_msg(const char *host, int addressfamily,
const char *reason)
{
return dupprintf("Looking up host \"%s\"%s for %s", host,
(addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
""), reason);
}
SockAddr *name_lookup(const char *host, int port, char **canonicalname,
Conf *conf, int addressfamily, LogContext *logctx,
const char *reason)
{
if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE &&
do_proxy_dns(conf) &&
proxy_for_destination(NULL, host, port, conf)) {
if (logctx)
logeventf(logctx, "Leaving host lookup to proxy of \"%s\""
" (for %s)", host, reason);
*canonicalname = dupstr(host);
return sk_nonamelookup(host);
} else {
if (logctx)
logevent_and_free(
logctx, dns_log_msg(host, addressfamily, reason));
return sk_namelookup(host, canonicalname, addressfamily);
}
}
static const SocketVtable ProxySocket_sockvt = {
.plug = sk_proxy_plug,
.close = sk_proxy_close,
.write = sk_proxy_write,
.write_oob = sk_proxy_write_oob,
.write_eof = sk_proxy_write_eof,
.set_frozen = sk_proxy_set_frozen,
.socket_error = sk_proxy_socket_error,
.peer_info = NULL,
};
static const PlugVtable ProxySocket_plugvt = {
.log = plug_proxy_log,
.closing = plug_proxy_closing,
.receive = plug_proxy_receive,
.sent = plug_proxy_sent,
.accepting = plug_proxy_accepting
};
static char *proxy_description(Interactor *itr)
{
ProxySocket *ps = container_of(itr, ProxySocket, interactor);
assert(ps->pn);
return dupprintf("%s connection to %s port %d", ps->pn->vt->type,
conf_get_str(ps->conf, CONF_proxy_host),
conf_get_int(ps->conf, CONF_proxy_port));
}
static LogPolicy *proxy_logpolicy(Interactor *itr)
{
ProxySocket *ps = container_of(itr, ProxySocket, interactor);
return ps->clientlp;
}
static Seat *proxy_get_seat(Interactor *itr)
{
ProxySocket *ps = container_of(itr, ProxySocket, interactor);
return ps->clientseat;
}
static void proxy_set_seat(Interactor *itr, Seat *seat)
{
ProxySocket *ps = container_of(itr, ProxySocket, interactor);
ps->clientseat = seat;
}
static const InteractorVtable ProxySocket_interactorvt = {
.description = proxy_description,
.logpolicy = proxy_logpolicy,
.get_seat = proxy_get_seat,
.set_seat = proxy_set_seat,
};
static void proxy_prompts_callback(void *ctx)
{
proxy_negotiate((ProxySocket *)ctx);
}
prompts_t *proxy_new_prompts(ProxySocket *ps)
{
prompts_t *prs = new_prompts();
prs->callback = proxy_prompts_callback;
prs->callback_ctx = ps;
return prs;
}
void proxy_spr_abort(ProxyNegotiator *pn, SeatPromptResult spr)
{
if (spr.kind == SPRK_SW_ABORT) {
pn->error = spr_get_error_message(spr);
} else {
assert(spr.kind == SPRK_USER_ABORT);
pn->aborted = true;
}
}
Socket *new_connection(SockAddr *addr, const char *hostname,
int port, bool privport,
bool oobinline, bool nodelay, bool keepalive,
Plug *plug, Conf *conf, Interactor *itr)
{
int type = conf_get_int(conf, CONF_proxy_type);
if (type != PROXY_NONE &&
proxy_for_destination(addr, hostname, port, conf))
{
ProxySocket *ps;
SockAddr *proxy_addr;
char *proxy_canonical_name;
Socket *sret;
if ((type == PROXY_SSH_TCPIP ||
type == PROXY_SSH_EXEC ||
type == PROXY_SSH_SUBSYSTEM) &&
(sret = sshproxy_new_connection(addr, hostname, port, privport,
oobinline, nodelay, keepalive,
plug, conf, itr)) != NULL)
return sret;
if ((sret = platform_new_connection(addr, hostname, port, privport,
oobinline, nodelay, keepalive,
plug, conf, itr)) != NULL)
return sret;
ps = snew(ProxySocket);
ps->sock.vt = &ProxySocket_sockvt;
ps->plugimpl.vt = &ProxySocket_plugvt;
ps->interactor.vt = &ProxySocket_interactorvt;
ps->conf = conf_copy(conf);
ps->plug = plug;
ps->remote_addr = addr; /* will need to be freed on close */
ps->remote_port = port;
ps->error = NULL;
ps->pending_eof = false;
ps->freeze = false;
bufchain_init(&ps->pending_input_data);
bufchain_init(&ps->pending_output_data);
bufchain_init(&ps->pending_oob_output_data);
bufchain_init(&ps->output_from_negotiator);
ps->sub_socket = NULL;
/*
* If we've been given an Interactor by the caller, set ourselves
* up to work with it.
*/
if (itr) {
ps->clientitr = itr;
interactor_set_child(ps->clientitr, &ps->interactor);
ps->clientlp = interactor_logpolicy(ps->clientitr);
ps->clientseat = interactor_borrow_seat(ps->clientitr);
}
const ProxyNegotiatorVT *vt;
switch (type) {
case PROXY_HTTP:
vt = &http_proxy_negotiator_vt;
break;
case PROXY_SOCKS4:
vt = &socks4_proxy_negotiator_vt;
break;
case PROXY_SOCKS5:
vt = &socks5_proxy_negotiator_vt;
break;
case PROXY_TELNET:
vt = &telnet_proxy_negotiator_vt;
break;
default:
ps->error = "Proxy error: Unknown proxy method";
return &ps->sock;
}
ps->pn = proxy_negotiator_new(vt);
ps->pn->ps = ps;
ps->pn->done = false;
ps->pn->error = NULL;
ps->pn->aborted = false;
ps->pn->input = &ps->pending_input_data;
/* Provide an Interactor to the negotiator if and only if we
* are usefully able to ask interactive questions of the user */
ps->pn->itr = ps->clientseat ? &ps->interactor : NULL;
bufchain_sink_init(ps->pn->output, &ps->output_from_negotiator);
{
char *logmsg = dupprintf("Will use %s proxy at %s:%d to connect"
" to %s:%d", vt->type,
conf_get_str(conf, CONF_proxy_host),
conf_get_int(conf, CONF_proxy_port),
hostname, port);
plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
sfree(logmsg);
}
{
char *logmsg = dns_log_msg(conf_get_str(conf, CONF_proxy_host),
conf_get_int(conf, CONF_addressfamily),
"proxy");
plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
sfree(logmsg);
}
/* look-up proxy */
proxy_addr = sk_namelookup(conf_get_str(conf, CONF_proxy_host),
&proxy_canonical_name,
conf_get_int(conf, CONF_addressfamily));
if (sk_addr_error(proxy_addr) != NULL) {
ps->error = "Proxy error: Unable to resolve proxy host name";
sk_addr_free(proxy_addr);
return &ps->sock;
}
sfree(proxy_canonical_name);
{
char addrbuf[256], *logmsg;
sk_getaddr(proxy_addr, addrbuf, lenof(addrbuf));
logmsg = dupprintf("Connecting to %s proxy at %s port %d",
vt->type, addrbuf,
conf_get_int(conf, CONF_proxy_port));
plug_log(plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
sfree(logmsg);
}
/* create the actual socket we will be using,
* connected to our proxy server and port.
*/
ps->proxy_addr = sk_addr_dup(proxy_addr);
ps->proxy_port = conf_get_int(conf, CONF_proxy_port);
ps->proxy_privport = privport;
ps->proxy_oobinline = oobinline;
ps->proxy_nodelay = nodelay;
ps->proxy_keepalive = keepalive;
ps->sub_socket = sk_new(proxy_addr, ps->proxy_port,
ps->proxy_privport, ps->proxy_oobinline,
ps->proxy_nodelay, ps->proxy_keepalive,
&ps->plugimpl);
if (sk_socket_error(ps->sub_socket) != NULL)
return &ps->sock;
/* start the proxy negotiation process... */
sk_set_frozen(ps->sub_socket, false);
proxy_negotiate(ps);
return &ps->sock;
}
/* no proxy, so just return the direct socket */
return sk_new(addr, port, privport, oobinline, nodelay, keepalive, plug);
}
Socket *new_listener(const char *srcaddr, int port, Plug *plug,
bool local_host_only, Conf *conf, int addressfamily)
{
/* TODO: SOCKS (and potentially others) support inbound
* TODO: connections via the proxy. support them.
*/
return sk_newlistener(srcaddr, port, plug, local_host_only, addressfamily);
}
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