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putty/proxy.c

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51 KiB
C
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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))
/*
* Call this when proxy negotiation is complete, so that this
* socket can begin working normally.
*/
void proxy_activate (ProxySocket *p)
{
size_t output_before, output_after;
p->state = PROXY_STATE_ACTIVE;
/* we want to ignore new receive events until we have sent
* all of our buffered receive data.
*/
sk_set_frozen(p->sub_socket, true);
/* how many bytes of output have we buffered? */
output_before = bufchain_size(&p->pending_oob_output_data) +
bufchain_size(&p->pending_output_data);
/* and keep track of how many bytes do not get sent. */
output_after = 0;
/* send buffered OOB writes */
while (bufchain_size(&p->pending_oob_output_data) > 0) {
ptrlen data = bufchain_prefix(&p->pending_oob_output_data);
output_after += sk_write_oob(p->sub_socket, data.ptr, data.len);
bufchain_consume(&p->pending_oob_output_data, data.len);
}
/* send buffered normal writes */
while (bufchain_size(&p->pending_output_data) > 0) {
ptrlen data = bufchain_prefix(&p->pending_output_data);
output_after += sk_write(p->sub_socket, data.ptr, data.len);
bufchain_consume(&p->pending_output_data, data.len);
}
/* if we managed to send any data, let the higher levels know. */
if (output_after < output_before)
plug_sent(p->plug, output_after);
/* if we have a pending EOF to send, send it */
if (p->pending_eof) sk_write_eof(p->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 (!p->freeze)
sk_set_frozen(&p->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->remote_addr);
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->state != PROXY_STATE_ACTIVE) {
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->state != PROXY_STATE_ACTIVE) {
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->state != PROXY_STATE_ACTIVE) {
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->state != PROXY_STATE_ACTIVE) {
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, const char *error_msg,
int error_code, bool calling_back)
{
ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
if (ps->state != PROXY_STATE_ACTIVE) {
ps->closing_error_msg = error_msg;
ps->closing_error_code = error_code;
ps->closing_calling_back = calling_back;
ps->negotiate(ps, PROXY_CHANGE_CLOSING);
} else {
plug_closing(ps->plug, error_msg, error_code, calling_back);
}
}
static void plug_proxy_receive(
Plug *p, int urgent, const char *data, size_t len)
{
ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
if (ps->state != PROXY_STATE_ACTIVE) {
/* 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);
ps->receive_urgent = (urgent != 0);
ps->receive_data = data;
ps->receive_len = len;
ps->negotiate(ps, PROXY_CHANGE_RECEIVE);
} 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->state != PROXY_STATE_ACTIVE) {
ps->negotiate(ps, PROXY_CHANGE_SENT);
return;
}
plug_sent(ps->plug, bufsize);
}
static int plug_proxy_accepting(Plug *p,
accept_fn_t constructor, accept_ctx_t ctx)
{
ProxySocket *ps = container_of(p, ProxySocket, plugimpl);
if (ps->state != PROXY_STATE_ACTIVE) {
ps->accepting_constructor = constructor;
ps->accepting_ctx = ctx;
return ps->negotiate(ps, PROXY_CHANGE_ACCEPTING);
}
return plug_accepting(ps->plug, constructor, ctx);
}
/*
* 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
};
Socket *new_connection(SockAddr *addr, const char *hostname,
int port, bool privport,
bool oobinline, bool nodelay, bool keepalive,
Plug *plug, Conf *conf)
{
if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE &&
proxy_for_destination(addr, hostname, port, conf))
{
ProxySocket *ret;
SockAddr *proxy_addr;
char *proxy_canonical_name;
const char *proxy_type;
Socket *sret;
int type;
if ((sret = platform_new_connection(addr, hostname, port, privport,
oobinline, nodelay, keepalive,
plug, conf)) !=
NULL)
return sret;
ret = snew(ProxySocket);
ret->sock.vt = &ProxySocket_sockvt;
ret->plugimpl.vt = &ProxySocket_plugvt;
ret->conf = conf_copy(conf);
ret->plug = plug;
ret->remote_addr = addr; /* will need to be freed on close */
ret->remote_port = port;
ret->error = NULL;
ret->pending_eof = false;
ret->freeze = false;
bufchain_init(&ret->pending_input_data);
bufchain_init(&ret->pending_output_data);
bufchain_init(&ret->pending_oob_output_data);
ret->sub_socket = NULL;
ret->state = PROXY_STATE_NEW;
ret->negotiate = NULL;
type = conf_get_int(conf, CONF_proxy_type);
if (type == PROXY_HTTP) {
ret->negotiate = proxy_http_negotiate;
proxy_type = "HTTP";
} else if (type == PROXY_SOCKS4) {
ret->negotiate = proxy_socks4_negotiate;
proxy_type = "SOCKS 4";
} else if (type == PROXY_SOCKS5) {
ret->negotiate = proxy_socks5_negotiate;
proxy_type = "SOCKS 5";
} else if (type == PROXY_TELNET) {
ret->negotiate = proxy_telnet_negotiate;
proxy_type = "Telnet";
} else {
ret->error = "Proxy error: Unknown proxy method";
return &ret->sock;
}
{
char *logmsg = dupprintf("Will use %s proxy at %s:%d to connect"
" to %s:%d", proxy_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) {
ret->error = "Proxy error: Unable to resolve proxy host name";
sk_addr_free(proxy_addr);
return &ret->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",
proxy_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.
*/
ret->sub_socket = sk_new(proxy_addr,
conf_get_int(conf, CONF_proxy_port),
privport, oobinline,
nodelay, keepalive, &ret->plugimpl);
if (sk_socket_error(ret->sub_socket) != NULL)
return &ret->sock;
/* start the proxy negotiation process... */
sk_set_frozen(ret->sub_socket, false);
ret->negotiate(ret, PROXY_CHANGE_NEW);
return &ret->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);
}
/* ----------------------------------------------------------------------
* HTTP CONNECT proxy type.
*/
static bool get_line_end(char *data, size_t len, size_t *out)
{
size_t off = 0;
while (off < len)
{
if (data[off] == '\n') {
/* we have a newline */
off++;
/* is that the only thing on this line? */
if (off <= 2) {
*out = off;
return true;
}
/* if not, then there is the possibility that this header
* continues onto the next line, if it starts with a space
* or a tab.
*/
if (off + 1 < len && data[off+1] != ' ' && data[off+1] != '\t') {
*out = off;
return true;
}
/* the line does continue, so we have to keep going
* until we see an the header's "real" end of line.
*/
off++;
}
off++;
}
return false;
}
int proxy_http_negotiate (ProxySocket *p, int change)
{
if (p->state == PROXY_STATE_NEW) {
/* we are just beginning the proxy negotiate process,
* so we'll send off the initial bits of the request.
* for this proxy method, it's just a simple HTTP
* request
*/
char *buf, dest[512];
char *username, *password;
sk_getaddr(p->remote_addr, dest, lenof(dest));
buf = dupprintf("CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n",
dest, p->remote_port, dest, p->remote_port);
sk_write(p->sub_socket, buf, strlen(buf));
sfree(buf);
username = conf_get_str(p->conf, CONF_proxy_username);
password = conf_get_str(p->conf, CONF_proxy_password);
if (username[0] || password[0]) {
char *buf, *buf2;
int i, j, len;
buf = dupprintf("%s:%s", username, password);
len = strlen(buf);
buf2 = snewn(len * 4 / 3 + 100, char);
sprintf(buf2, "Proxy-Authorization: Basic ");
for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4)
base64_encode_atom((unsigned char *)(buf+i),
(len-i > 3 ? 3 : len-i), buf2+j);
strcpy(buf2+j, "\r\n");
sk_write(p->sub_socket, buf2, strlen(buf2));
sfree(buf);
sfree(buf2);
}
sk_write(p->sub_socket, "\r\n", 2);
p->state = 1;
return 0;
}
if (change == PROXY_CHANGE_CLOSING) {
/* if our proxy negotiation process involves closing and opening
* new sockets, then we would want to intercept this closing
* callback when we were expecting it. if we aren't anticipating
* a socket close, then some error must have occurred. we'll
* just pass those errors up to the backend.
*/
plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
p->closing_calling_back);
return 0; /* ignored */
}
if (change == PROXY_CHANGE_SENT) {
/* some (or all) of what we wrote to the proxy was sent.
* we don't do anything new, however, until we receive the
* proxy's response. we might want to set a timer so we can
* timeout the proxy negotiation after a while...
*/
return 0;
}
if (change == PROXY_CHANGE_ACCEPTING) {
/* we should _never_ see this, as we are using our socket to
* connect to a proxy, not accepting inbound connections.
* what should we do? close the socket with an appropriate
* error message?
*/
return plug_accepting(p->plug,
p->accepting_constructor, p->accepting_ctx);
}
if (change == PROXY_CHANGE_RECEIVE) {
/* we have received data from the underlying socket, which
* we'll need to parse, process, and respond to appropriately.
*/
char *data, *datap;
size_t len, eol;
if (p->state == 1) {
int min_ver, maj_ver, status;
/* get the status line */
len = bufchain_size(&p->pending_input_data);
assert(len > 0); /* or we wouldn't be here */
data = snewn(len+1, char);
bufchain_fetch(&p->pending_input_data, data, len);
/*
* We must NUL-terminate this data, because Windows
* sscanf appears to require a NUL at the end of the
* string because it strlens it _first_. Sigh.
*/
data[len] = '\0';
if (!get_line_end(data, len, &eol)) {
sfree(data);
return 1;
}
status = -1;
/* We can't rely on whether the %n incremented the sscanf return */
if (sscanf((char *)data, "HTTP/%i.%i %n",
&maj_ver, &min_ver, &status) < 2 || status == -1) {
plug_closing(p->plug, "Proxy error: HTTP response was absent",
PROXY_ERROR_GENERAL, 0);
sfree(data);
return 1;
}
/* remove the status line from the input buffer. */
bufchain_consume(&p->pending_input_data, eol);
if (data[status] != '2') {
/* error */
char *buf;
data[eol] = '\0';
while (eol > status &&
(data[eol-1] == '\r' || data[eol-1] == '\n'))
data[--eol] = '\0';
buf = dupprintf("Proxy error: %s", data+status);
plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
sfree(buf);
sfree(data);
return 1;
}
sfree(data);
p->state = 2;
}
if (p->state == 2) {
/* get headers. we're done when we get a
* header of length 2, (ie. just "\r\n")
*/
len = bufchain_size(&p->pending_input_data);
assert(len > 0); /* or we wouldn't be here */
data = snewn(len, char);
datap = data;
bufchain_fetch(&p->pending_input_data, data, len);
if (!get_line_end(datap, len, &eol)) {
sfree(data);
return 1;
}
while (eol > 2) {
bufchain_consume(&p->pending_input_data, eol);
datap += eol;
len -= eol;
if (!get_line_end(datap, len, &eol))
eol = 0; /* terminate the loop */
}
if (eol == 2) {
/* we're done */
bufchain_consume(&p->pending_input_data, 2);
proxy_activate(p);
/* proxy activate will have dealt with
* whatever is left of the buffer */
sfree(data);
return 1;
}
sfree(data);
return 1;
}
}
plug_closing(p->plug, "Proxy error: unexpected proxy error",
PROXY_ERROR_UNEXPECTED, 0);
return 1;
}
/* ----------------------------------------------------------------------
* SOCKS proxy type.
*/
/* SOCKS version 4 */
int proxy_socks4_negotiate (ProxySocket *p, int change)
{
if (p->state == PROXY_CHANGE_NEW) {
/* request format:
* version number (1 byte) = 4
* command code (1 byte)
* 1 = CONNECT
* 2 = BIND
* dest. port (2 bytes) [network order]
* dest. address (4 bytes)
* user ID (variable length, null terminated string)
*/
strbuf *command = strbuf_new();
char hostname[512];
bool write_hostname = false;
put_byte(command, 4); /* SOCKS version 4 */
put_byte(command, 1); /* CONNECT command */
put_uint16(command, p->remote_port);
switch (sk_addrtype(p->remote_addr)) {
case ADDRTYPE_IPV4: {
char addr[4];
sk_addrcopy(p->remote_addr, addr);
put_data(command, addr, 4);
break;
}
case ADDRTYPE_NAME:
sk_getaddr(p->remote_addr, hostname, lenof(hostname));
put_uint32(command, 1);
write_hostname = true;
break;
case ADDRTYPE_IPV6:
p->error = "Proxy error: SOCKS version 4 does not support IPv6";
strbuf_free(command);
return 1;
}
put_asciz(command, conf_get_str(p->conf, CONF_proxy_username));
if (write_hostname)
put_asciz(command, hostname);
sk_write(p->sub_socket, command->s, command->len);
strbuf_free(command);
p->state = 1;
return 0;
}
if (change == PROXY_CHANGE_CLOSING) {
/* if our proxy negotiation process involves closing and opening
* new sockets, then we would want to intercept this closing
* callback when we were expecting it. if we aren't anticipating
* a socket close, then some error must have occurred. we'll
* just pass those errors up to the backend.
*/
plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
p->closing_calling_back);
return 0; /* ignored */
}
if (change == PROXY_CHANGE_SENT) {
/* some (or all) of what we wrote to the proxy was sent.
* we don't do anything new, however, until we receive the
* proxy's response. we might want to set a timer so we can
* timeout the proxy negotiation after a while...
*/
return 0;
}
if (change == PROXY_CHANGE_ACCEPTING) {
/* we should _never_ see this, as we are using our socket to
* connect to a proxy, not accepting inbound connections.
* what should we do? close the socket with an appropriate
* error message?
*/
return plug_accepting(p->plug,
p->accepting_constructor, p->accepting_ctx);
}
if (change == PROXY_CHANGE_RECEIVE) {
/* we have received data from the underlying socket, which
* we'll need to parse, process, and respond to appropriately.
*/
if (p->state == 1) {
/* response format:
* version number (1 byte) = 4
* reply code (1 byte)
* 90 = request granted
* 91 = request rejected or failed
* 92 = request rejected due to lack of IDENTD on client
* 93 = request rejected due to difference in user ID
* (what we sent vs. what IDENTD said)
* dest. port (2 bytes)
* dest. address (4 bytes)
*/
char data[8];
if (bufchain_size(&p->pending_input_data) < 8)
return 1; /* not got anything yet */
/* get the response */
bufchain_fetch(&p->pending_input_data, data, 8);
if (data[0] != 0) {
plug_closing(p->plug, "Proxy error: SOCKS proxy responded with "
"unexpected reply code version",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (data[1] != 90) {
switch (data[1]) {
case 92:
plug_closing(p->plug, "Proxy error: SOCKS server wanted IDENTD on client",
PROXY_ERROR_GENERAL, 0);
break;
case 93:
plug_closing(p->plug, "Proxy error: Username and IDENTD on client don't agree",
PROXY_ERROR_GENERAL, 0);
break;
case 91:
default:
plug_closing(p->plug, "Proxy error: Error while communicating with proxy",
PROXY_ERROR_GENERAL, 0);
break;
}
return 1;
}
bufchain_consume(&p->pending_input_data, 8);
/* we're done */
proxy_activate(p);
/* proxy activate will have dealt with
* whatever is left of the buffer */
return 1;
}
}
plug_closing(p->plug, "Proxy error: unexpected proxy error",
PROXY_ERROR_UNEXPECTED, 0);
return 1;
}
/* SOCKS version 5 */
int proxy_socks5_negotiate (ProxySocket *p, int change)
{
if (p->state == PROXY_CHANGE_NEW) {
/* initial command:
* version number (1 byte) = 5
* number of available authentication methods (1 byte)
* available authentication methods (1 byte * previous value)
* authentication methods:
* 0x00 = no authentication
* 0x01 = GSSAPI
* 0x02 = username/password
* 0x03 = CHAP
*/
strbuf *command;
char *username, *password;
int method_count_offset, methods_start;
command = strbuf_new();
put_byte(command, 5); /* SOCKS version 5 */
username = conf_get_str(p->conf, CONF_proxy_username);
password = conf_get_str(p->conf, CONF_proxy_password);
method_count_offset = command->len;
put_byte(command, 0);
methods_start = command->len;
put_byte(command, 0x00); /* no authentication */
if (username[0] || password[0]) {
proxy_socks5_offerencryptedauth(BinarySink_UPCAST(command));
put_byte(command, 0x02); /* username/password */
}
command->u[method_count_offset] = command->len - methods_start;
sk_write(p->sub_socket, command->s, command->len);
strbuf_free(command);
p->state = 1;
return 0;
}
if (change == PROXY_CHANGE_CLOSING) {
/* if our proxy negotiation process involves closing and opening
* new sockets, then we would want to intercept this closing
* callback when we were expecting it. if we aren't anticipating
* a socket close, then some error must have occurred. we'll
* just pass those errors up to the backend.
*/
plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
p->closing_calling_back);
return 0; /* ignored */
}
if (change == PROXY_CHANGE_SENT) {
/* some (or all) of what we wrote to the proxy was sent.
* we don't do anything new, however, until we receive the
* proxy's response. we might want to set a timer so we can
* timeout the proxy negotiation after a while...
*/
return 0;
}
if (change == PROXY_CHANGE_ACCEPTING) {
/* we should _never_ see this, as we are using our socket to
* connect to a proxy, not accepting inbound connections.
* what should we do? close the socket with an appropriate
* error message?
*/
return plug_accepting(p->plug,
p->accepting_constructor, p->accepting_ctx);
}
if (change == PROXY_CHANGE_RECEIVE) {
/* we have received data from the underlying socket, which
* we'll need to parse, process, and respond to appropriately.
*/
if (p->state == 1) {
/* initial response:
* version number (1 byte) = 5
* authentication method (1 byte)
* authentication methods:
* 0x00 = no authentication
* 0x01 = GSSAPI
* 0x02 = username/password
* 0x03 = CHAP
* 0xff = no acceptable methods
*/
char data[2];
if (bufchain_size(&p->pending_input_data) < 2)
return 1; /* not got anything yet */
/* get the response */
bufchain_fetch(&p->pending_input_data, data, 2);
if (data[0] != 5) {
plug_closing(p->plug, "Proxy error: SOCKS proxy returned unexpected version",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (data[1] == 0x00) p->state = 2; /* no authentication needed */
else if (data[1] == 0x01) p->state = 4; /* GSSAPI authentication */
else if (data[1] == 0x02) p->state = 5; /* username/password authentication */
else if (data[1] == 0x03) p->state = 6; /* CHAP authentication */
else {
plug_closing(p->plug, "Proxy error: SOCKS proxy did not accept our authentication",
PROXY_ERROR_GENERAL, 0);
return 1;
}
bufchain_consume(&p->pending_input_data, 2);
}
if (p->state == 7) {
/* password authentication reply format:
* version number (1 bytes) = 1
* reply code (1 byte)
* 0 = succeeded
* >0 = failed
*/
char data[2];
if (bufchain_size(&p->pending_input_data) < 2)
return 1; /* not got anything yet */
/* get the response */
bufchain_fetch(&p->pending_input_data, data, 2);
if (data[0] != 1) {
plug_closing(p->plug, "Proxy error: SOCKS password "
"subnegotiation contained wrong version number",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (data[1] != 0) {
plug_closing(p->plug, "Proxy error: SOCKS proxy refused"
" password authentication",
PROXY_ERROR_GENERAL, 0);
return 1;
}
bufchain_consume(&p->pending_input_data, 2);
p->state = 2; /* now proceed as authenticated */
}
if (p->state == 8) {
int ret;
ret = proxy_socks5_handlechap(p);
if (ret) return ret;
}
if (p->state == 2) {
/* request format:
* version number (1 byte) = 5
* command code (1 byte)
* 1 = CONNECT
* 2 = BIND
* 3 = UDP ASSOCIATE
* reserved (1 byte) = 0x00
* address type (1 byte)
* 1 = IPv4
* 3 = domainname (first byte has length, no terminating null)
* 4 = IPv6
* dest. address (variable)
* dest. port (2 bytes) [network order]
*/
strbuf *command = strbuf_new();
put_byte(command, 5); /* SOCKS version 5 */
put_byte(command, 1); /* CONNECT command */
put_byte(command, 0x00); /* reserved byte */
switch (sk_addrtype(p->remote_addr)) {
case ADDRTYPE_IPV4:
put_byte(command, 1); /* IPv4 */
sk_addrcopy(p->remote_addr, strbuf_append(command, 4));
break;
case ADDRTYPE_IPV6:
put_byte(command, 4); /* IPv6 */
sk_addrcopy(p->remote_addr, strbuf_append(command, 16));
break;
case ADDRTYPE_NAME: {
char hostname[512];
put_byte(command, 3); /* domain name */
sk_getaddr(p->remote_addr, hostname, lenof(hostname));
if (!put_pstring(command, hostname)) {
p->error = "Proxy error: SOCKS 5 cannot "
"support host names longer than 255 chars";
strbuf_free(command);
return 1;
}
break;
}
}
put_uint16(command, p->remote_port);
sk_write(p->sub_socket, command->s, command->len);
strbuf_free(command);
p->state = 3;
return 1;
}
if (p->state == 3) {
/* reply format:
* version number (1 bytes) = 5
* reply code (1 byte)
* 0 = succeeded
* 1 = general SOCKS server failure
* 2 = connection not allowed by ruleset
* 3 = network unreachable
* 4 = host unreachable
* 5 = connection refused
* 6 = TTL expired
* 7 = command not supported
* 8 = address type not supported
* reserved (1 byte) = x00
* address type (1 byte)
* 1 = IPv4
* 3 = domainname (first byte has length, no terminating null)
* 4 = IPv6
* server bound address (variable)
* server bound port (2 bytes) [network order]
*/
char data[5];
int len;
/* First 5 bytes of packet are enough to tell its length. */
if (bufchain_size(&p->pending_input_data) < 5)
return 1; /* not got anything yet */
/* get the response */
bufchain_fetch(&p->pending_input_data, data, 5);
if (data[0] != 5) {
plug_closing(p->plug, "Proxy error: SOCKS proxy returned wrong version number",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (data[1] != 0) {
char buf[256];
strcpy(buf, "Proxy error: ");
switch (data[1]) {
case 1: strcat(buf, "General SOCKS server failure"); break;
case 2: strcat(buf, "Connection not allowed by ruleset"); break;
case 3: strcat(buf, "Network unreachable"); break;
case 4: strcat(buf, "Host unreachable"); break;
case 5: strcat(buf, "Connection refused"); break;
case 6: strcat(buf, "TTL expired"); break;
case 7: strcat(buf, "Command not supported"); break;
case 8: strcat(buf, "Address type not supported"); break;
default: sprintf(buf+strlen(buf),
"Unrecognised SOCKS error code %d",
data[1]);
break;
}
plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
return 1;
}
/*
* Eat the rest of the reply packet.
*/
len = 6; /* first 4 bytes, last 2 */
switch (data[3]) {
case 1: len += 4; break; /* IPv4 address */
case 4: len += 16; break;/* IPv6 address */
case 3: len += 1+(unsigned char)data[4]; break; /* domain name */
default:
plug_closing(p->plug, "Proxy error: SOCKS proxy returned "
"unrecognised address format",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (bufchain_size(&p->pending_input_data) < len)
return 1; /* not got whole reply yet */
bufchain_consume(&p->pending_input_data, len);
/* we're done */
proxy_activate(p);
return 1;
}
if (p->state == 4) {
/* TODO: Handle GSSAPI authentication */
plug_closing(p->plug, "Proxy error: We don't support GSSAPI authentication",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (p->state == 5) {
const char *username = conf_get_str(p->conf, CONF_proxy_username);
const char *password = conf_get_str(p->conf, CONF_proxy_password);
if (username[0] || password[0]) {
strbuf *auth = strbuf_new_nm();
put_byte(auth, 1); /* version number of subnegotiation */
if (!put_pstring(auth, username)) {
p->error = "Proxy error: SOCKS 5 authentication cannot "
"support usernames longer than 255 chars";
strbuf_free(auth);
return 1;
}
if (!put_pstring(auth, password)) {
p->error = "Proxy error: SOCKS 5 authentication cannot "
"support passwords longer than 255 chars";
strbuf_free(auth);
return 1;
}
sk_write(p->sub_socket, auth->s, auth->len);
strbuf_free(auth);
p->state = 7;
} else
plug_closing(p->plug, "Proxy error: Server chose "
"username/password authentication but we "
"didn't offer it!",
PROXY_ERROR_GENERAL, 0);
return 1;
}
if (p->state == 6) {
int ret;
ret = proxy_socks5_selectchap(p);
if (ret) return ret;
}
}
plug_closing(p->plug, "Proxy error: Unexpected proxy error",
PROXY_ERROR_UNEXPECTED, 0);
return 1;
}
/* ----------------------------------------------------------------------
* `Telnet' proxy type.
*
* (This is for ad-hoc proxies where you connect to the proxy's
* telnet port and send a command such as `connect host port'. The
* command is configurable, since this proxy type is typically not
* standardised or at all well-defined.)
*/
char *format_telnet_command(SockAddr *addr, int port, Conf *conf)
{
char *fmt = conf_get_str(conf, CONF_proxy_telnet_command);
int so = 0, eo = 0;
strbuf *buf = strbuf_new();
/* we need to escape \\, \%, \r, \n, \t, \x??, \0???,
* %%, %host, %port, %user, and %pass
*/
while (fmt[eo] != 0) {
/* scan forward until we hit end-of-line,
* or an escape character (\ or %) */
while (fmt[eo] != 0 && fmt[eo] != '%' && fmt[eo] != '\\')
eo++;
/* if we hit eol, break out of our escaping loop */
if (fmt[eo] == 0) break;
/* if there was any unescaped text before the escape
* character, send that now */
if (eo != so)
put_data(buf, fmt + so, eo - so);
so = eo++;
/* if the escape character was the last character of
* the line, we'll just stop and send it. */
if (fmt[eo] == 0) break;
if (fmt[so] == '\\') {
/* we recognize \\, \%, \r, \n, \t, \x??.
* anything else, we just send unescaped (including the \).
*/
switch (fmt[eo]) {
case '\\':
put_byte(buf, '\\');
eo++;
break;
case '%':
put_byte(buf, '%');
eo++;
break;
case 'r':
put_byte(buf, '\r');
eo++;
break;
case 'n':
put_byte(buf, '\n');
eo++;
break;
case 't':
put_byte(buf, '\t');
eo++;
break;
case 'x':
case 'X': {
/* escaped hexadecimal value (ie. \xff) */
unsigned char v = 0;
int i = 0;
for (;;) {
eo++;
if (fmt[eo] >= '0' && fmt[eo] <= '9')
v += fmt[eo] - '0';
else if (fmt[eo] >= 'a' && fmt[eo] <= 'f')
v += fmt[eo] - 'a' + 10;
else if (fmt[eo] >= 'A' && fmt[eo] <= 'F')
v += fmt[eo] - 'A' + 10;
else {
/* non hex character, so we abort and just
* send the whole thing unescaped (including \x)
*/
put_byte(buf, '\\');
eo = so + 1;
break;
}
/* we only extract two hex characters */
if (i == 1) {
put_byte(buf, v);
eo++;
break;
}
i++;
v <<= 4;
}
break;
}
default:
put_data(buf, fmt + so, 2);
eo++;
break;
}
} else {
/* % escape. we recognize %%, %host, %port, %user, %pass.
* %proxyhost, %proxyport. Anything else we just send
* unescaped (including the %).
*/
if (fmt[eo] == '%') {
put_byte(buf, '%');
eo++;
}
else if (strnicmp(fmt + eo, "host", 4) == 0) {
char dest[512];
sk_getaddr(addr, dest, lenof(dest));
put_data(buf, dest, strlen(dest));
eo += 4;
}
else if (strnicmp(fmt + eo, "port", 4) == 0) {
strbuf_catf(buf, "%d", port);
eo += 4;
}
else if (strnicmp(fmt + eo, "user", 4) == 0) {
const char *username = conf_get_str(conf, CONF_proxy_username);
put_data(buf, username, strlen(username));
eo += 4;
}
else if (strnicmp(fmt + eo, "pass", 4) == 0) {
const char *password = conf_get_str(conf, CONF_proxy_password);
put_data(buf, password, strlen(password));
eo += 4;
}
else if (strnicmp(fmt + eo, "proxyhost", 9) == 0) {
const char *host = conf_get_str(conf, CONF_proxy_host);
put_data(buf, host, strlen(host));
eo += 9;
}
else if (strnicmp(fmt + eo, "proxyport", 9) == 0) {
int port = conf_get_int(conf, CONF_proxy_port);
strbuf_catf(buf, "%d", port);
eo += 9;
}
else {
/* we don't escape this, so send the % now, and
* don't advance eo, so that we'll consider the
* text immediately following the % as unescaped.
*/
put_byte(buf, '%');
}
}
/* resume scanning for additional escapes after this one. */
so = eo;
}
/* if there is any unescaped text at the end of the line, send it */
if (eo != so) {
put_data(buf, fmt + so, eo - so);
}
return strbuf_to_str(buf);
}
int proxy_telnet_negotiate (ProxySocket *p, int change)
{
if (p->state == PROXY_CHANGE_NEW) {
char *formatted_cmd;
formatted_cmd = format_telnet_command(p->remote_addr, p->remote_port,
p->conf);
{
/*
* Re-escape control chars in the command, for logging.
*/
char *reescaped = snewn(4*strlen(formatted_cmd) + 1, char);
const char *in;
char *out;
char *logmsg;
for (in = formatted_cmd, out = reescaped; *in; in++) {
if (*in == '\n') {
*out++ = '\\'; *out++ = 'n';
} else if (*in == '\r') {
*out++ = '\\'; *out++ = 'r';
} else if (*in == '\t') {
*out++ = '\\'; *out++ = 't';
} else if (*in == '\\') {
*out++ = '\\'; *out++ = '\\';
} else if ((unsigned)(((unsigned char)*in) - 0x20) <
(0x7F-0x20)) {
*out++ = *in;
} else {
out += sprintf(out, "\\x%02X", (unsigned)*in & 0xFF);
}
}
*out = '\0';
logmsg = dupprintf("Sending Telnet proxy command: %s", reescaped);
plug_log(p->plug, PLUGLOG_PROXY_MSG, NULL, 0, logmsg, 0);
sfree(logmsg);
sfree(reescaped);
}
sk_write(p->sub_socket, formatted_cmd, strlen(formatted_cmd));
sfree(formatted_cmd);
p->state = 1;
return 0;
}
if (change == PROXY_CHANGE_CLOSING) {
/* if our proxy negotiation process involves closing and opening
* new sockets, then we would want to intercept this closing
* callback when we were expecting it. if we aren't anticipating
* a socket close, then some error must have occurred. we'll
* just pass those errors up to the backend.
*/
plug_closing(p->plug, p->closing_error_msg, p->closing_error_code,
p->closing_calling_back);
return 0; /* ignored */
}
if (change == PROXY_CHANGE_SENT) {
/* some (or all) of what we wrote to the proxy was sent.
* we don't do anything new, however, until we receive the
* proxy's response. we might want to set a timer so we can
* timeout the proxy negotiation after a while...
*/
return 0;
}
if (change == PROXY_CHANGE_ACCEPTING) {
/* we should _never_ see this, as we are using our socket to
* connect to a proxy, not accepting inbound connections.
* what should we do? close the socket with an appropriate
* error message?
*/
return plug_accepting(p->plug,
p->accepting_constructor, p->accepting_ctx);
}
if (change == PROXY_CHANGE_RECEIVE) {
/* we have received data from the underlying socket, which
* we'll need to parse, process, and respond to appropriately.
*/
/* we're done */
proxy_activate(p);
/* proxy activate will have dealt with
* whatever is left of the buffer */
return 1;
}
plug_closing(p->plug, "Proxy error: Unexpected proxy error",
PROXY_ERROR_UNEXPECTED, 0);
return 1;
}
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