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putty-source/proxy.c
Jacob Nevins 71a97ab286 Initialise some members of the Proxy_Socket structure that were left 
uninitialised. This problem only showed up with mingw builds of PuTTY
(maybe MSVCRT is more forgiving with malloc initialisation than CRTDLL?).
The 'error' field was causing me most trouble, and I think the other two
were necessary too before things started working.
Note however that I don't fully understand the code, and that there are
more uninitialised fields in the structure.

[originally from svn r2029]
2002-10-11 12:29:27 +00:00

1269 lines
34 KiB
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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 <windows.h>
#include <assert.h>
#define DEFINE_PLUG_METHOD_MACROS
#include "putty.h"
#include "network.h"
#include "proxy.h"
/*
* Call this when proxy negotiation is complete, so that this
* socket can begin working normally.
*/
void proxy_activate (Proxy_Socket p)
{
void *data;
int len;
p->state = PROXY_STATE_ACTIVE;
/* let's try to keep extra receive events from coming through */
sk_set_frozen(p->sub_socket, 1);
/* send buffered OOB writes */
while (bufchain_size(&p->pending_oob_output_data) > 0) {
bufchain_prefix(&p->pending_oob_output_data, &data, &len);
sk_write_oob(p->sub_socket, data, len);
bufchain_consume(&p->pending_oob_output_data, len);
}
bufchain_clear(&p->pending_oob_output_data);
/* send buffered normal writes */
while (bufchain_size(&p->pending_output_data) > 0) {
bufchain_prefix(&p->pending_output_data, &data, &len);
sk_write(p->sub_socket, data, len);
bufchain_consume(&p->pending_output_data, len);
}
bufchain_clear(&p->pending_output_data);
/* if we were asked to flush the output during
* the proxy negotiation process, do so now.
*/
if (p->pending_flush) sk_flush(p->sub_socket);
/* forward buffered recv data to the backend */
while (bufchain_size(&p->pending_input_data) > 0) {
bufchain_prefix(&p->pending_input_data, &data, &len);
plug_receive(p->plug, 0, data, len);
bufchain_consume(&p->pending_input_data, len);
}
bufchain_clear(&p->pending_input_data);
/* now set the underlying socket to whatever freeze state they wanted */
sk_set_frozen(p->sub_socket, p->freeze);
}
/* basic proxy socket functions */
static Plug sk_proxy_plug (Socket s, Plug p)
{
Proxy_Socket ps = (Proxy_Socket) s;
Plug ret = ps->plug;
if (p)
ps->plug = p;
return ret;
}
static void sk_proxy_close (Socket s)
{
Proxy_Socket ps = (Proxy_Socket) s;
sk_close(ps->sub_socket);
sfree(ps);
}
static int sk_proxy_write (Socket s, char *data, int len)
{
Proxy_Socket ps = (Proxy_Socket) s;
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 int sk_proxy_write_oob (Socket s, char *data, int len)
{
Proxy_Socket ps = (Proxy_Socket) s;
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_flush (Socket s)
{
Proxy_Socket ps = (Proxy_Socket) s;
if (ps->state != PROXY_STATE_ACTIVE) {
ps->pending_flush = 1;
return;
}
sk_flush(ps->sub_socket);
}
static void sk_proxy_set_private_ptr (Socket s, void *ptr)
{
Proxy_Socket ps = (Proxy_Socket) s;
sk_set_private_ptr(ps->sub_socket, ptr);
}
static void * sk_proxy_get_private_ptr (Socket s)
{
Proxy_Socket ps = (Proxy_Socket) s;
return sk_get_private_ptr(ps->sub_socket);
}
static void sk_proxy_set_frozen (Socket s, int is_frozen)
{
Proxy_Socket ps = (Proxy_Socket) s;
if (ps->state != PROXY_STATE_ACTIVE) {
ps->freeze = is_frozen;
return;
}
sk_set_frozen(ps->sub_socket, is_frozen);
}
static char * sk_proxy_socket_error (Socket s)
{
Proxy_Socket ps = (Proxy_Socket) s;
if (ps->error != NULL || ps->sub_socket == NULL) {
return ps->error;
}
return sk_socket_error(ps->sub_socket);
}
/* basic proxy plug functions */
static int plug_proxy_closing (Plug p, char *error_msg,
int error_code, int calling_back)
{
Proxy_Plug pp = (Proxy_Plug) p;
Proxy_Socket ps = pp->proxy_socket;
if (ps->state != PROXY_STATE_ACTIVE) {
ps->closing_error_msg = error_msg;
ps->closing_error_code = error_code;
ps->closing_calling_back = calling_back;
return ps->negotiate(ps, PROXY_CHANGE_CLOSING);
}
return plug_closing(ps->plug, error_msg,
error_code, calling_back);
}
static int plug_proxy_receive (Plug p, int urgent, char *data, int len)
{
Proxy_Plug pp = (Proxy_Plug) p;
Proxy_Socket ps = pp->proxy_socket;
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;
ps->receive_data = data;
ps->receive_len = len;
return ps->negotiate(ps, PROXY_CHANGE_RECEIVE);
}
return plug_receive(ps->plug, urgent, data, len);
}
static void plug_proxy_sent (Plug p, int bufsize)
{
Proxy_Plug pp = (Proxy_Plug) p;
Proxy_Socket ps = pp->proxy_socket;
if (ps->state != PROXY_STATE_ACTIVE) {
ps->sent_bufsize = bufsize;
ps->negotiate(ps, PROXY_CHANGE_SENT);
return;
}
plug_sent(ps->plug, bufsize);
}
static int plug_proxy_accepting (Plug p, void *sock)
{
Proxy_Plug pp = (Proxy_Plug) p;
Proxy_Socket ps = pp->proxy_socket;
if (ps->state != PROXY_STATE_ACTIVE) {
ps->accepting_sock = sock;
return ps->negotiate(ps, PROXY_CHANGE_ACCEPTING);
}
return plug_accepting(ps->plug, sock);
}
static int proxy_for_destination (SockAddr addr, char * hostname, int port)
{
int s = 0, e = 0;
char hostip[64];
int hostip_len, hostname_len;
char * exclude_list;
/* we want a string representation of the IP address for comparisons */
sk_getaddr(addr, hostip, 64);
hostip_len = strlen(hostip);
hostname_len = strlen(hostname);
exclude_list = cfg.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(exclude_list[s]) ||
exclude_list[s] == ',')) s++;
if (!exclude_list[s]) break;
e = s;
while (exclude_list[e] &&
(isalnum(exclude_list[e]) ||
exclude_list[e] == '-' ||
exclude_list[e] == '.' ||
exclude_list[e] == '*')) e++;
if (exclude_list[s] == '*') {
/* wildcard at beginning of entry */
if (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)
return 0; /* IP/hostname range excluded. do not use proxy. */
} else if (exclude_list[e-1] == '*') {
/* wildcard at end of entry */
if (strnicmp(hostip, exclude_list + s, e - s - 1) == 0 ||
strnicmp(hostname, exclude_list + s, e - s - 1) == 0)
return 0; /* IP/hostname range excluded. do not use proxy. */
} else {
/* no wildcard at either end, so let's try an absolute
* match (ie. a specific IP)
*/
if (stricmp(hostip, exclude_list + s) == 0)
return 0; /* IP/hostname excluded. do not use proxy. */
if (stricmp(hostname, exclude_list + s) == 0)
return 0; /* IP/hostname excluded. do not use proxy. */
}
s = e;
}
/* no matches in the exclude list, so use the proxy */
return 1;
}
Socket new_connection(SockAddr addr, char *hostname,
int port, int privport,
int oobinline, int nodelay, Plug plug)
{
static struct socket_function_table socket_fn_table = {
sk_proxy_plug,
sk_proxy_close,
sk_proxy_write,
sk_proxy_write_oob,
sk_proxy_flush,
sk_proxy_set_private_ptr,
sk_proxy_get_private_ptr,
sk_proxy_set_frozen,
sk_proxy_socket_error
};
static struct plug_function_table plug_fn_table = {
plug_proxy_closing,
plug_proxy_receive,
plug_proxy_sent,
plug_proxy_accepting
};
if (cfg.proxy_type != PROXY_NONE &&
proxy_for_destination(addr, hostname, port))
{
Proxy_Socket ret;
Proxy_Plug pplug;
SockAddr proxy_addr;
char * proxy_canonical_name;
ret = smalloc(sizeof(struct Socket_proxy_tag));
ret->fn = &socket_fn_table;
ret->plug = plug;
ret->remote_addr = addr;
ret->remote_port = port;
/* XXX review these initialisations, and initialise other fields
* in Proxy_Socket structure */
ret->error = NULL;
ret->pending_flush = 0;
ret->freeze = 0;
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;
if (cfg.proxy_type == PROXY_HTTP) {
ret->negotiate = proxy_http_negotiate;
} else if (cfg.proxy_type == PROXY_SOCKS) {
if (cfg.proxy_socks_version == 4)
ret->negotiate = proxy_socks4_negotiate;
else
ret->negotiate = proxy_socks5_negotiate;
} else if (cfg.proxy_type == PROXY_TELNET) {
ret->negotiate = proxy_telnet_negotiate;
} else {
ret->error = "Proxy error: Unknown proxy method";
return (Socket) ret;
}
/* create the proxy plug to map calls from the actual
* socket into our proxy socket layer */
pplug = smalloc(sizeof(struct Plug_proxy_tag));
pplug->fn = &plug_fn_table;
pplug->proxy_socket = ret;
/* look-up proxy */
proxy_addr = sk_namelookup(cfg.proxy_host,
&proxy_canonical_name);
sfree(proxy_canonical_name);
/* create the actual socket we will be using,
* connected to our proxy server and port.
*/
ret->sub_socket = sk_new(proxy_addr, cfg.proxy_port,
privport, oobinline,
nodelay, (Plug) pplug);
if (sk_socket_error(ret->sub_socket) != NULL)
return (Socket) ret;
sk_addr_free(proxy_addr);
/* start the proxy negotiation process... */
sk_set_frozen(ret->sub_socket, 0);
ret->negotiate(ret, PROXY_CHANGE_NEW);
return (Socket) ret;
}
/* no proxy, so just return the direct socket */
return sk_new(addr, port, privport, oobinline, nodelay, plug);
}
Socket new_listener(int port, Plug plug, int local_host_only)
{
/* TODO: SOCKS (and potentially others) support inbound
* TODO: connections via the proxy. support them.
*/
return sk_newlistener(port, plug, local_host_only);
}
/* ----------------------------------------------------------------------
* HTTP CONNECT proxy type.
*/
static int get_line_end (char * data, int len)
{
int 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) return off;
/* 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') return off;
/* the line does continue, so we have to keep going
* until we see an the header's "real" end of line.
*/
off++;
}
off++;
}
return -1;
}
int proxy_http_negotiate (Proxy_Socket 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[256], dest[64];
sk_getaddr(p->remote_addr, dest, 64);
sprintf(buf, "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));
if (cfg.proxy_username[0] || cfg.proxy_password[0]) {
char buf[sizeof(cfg.proxy_username)+sizeof(cfg.proxy_password)];
char buf2[sizeof(buf)*4/3 + 100];
int i, j, len;
sprintf(buf, "%s:%s", cfg.proxy_username, cfg.proxy_password);
len = strlen(buf);
sprintf(buf2, "Proxy-Authorization: basic ");
for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4)
base64_encode_atom(buf+i, (len-i > 3 ? 3 : len-i), buf2+j);
strcpy(buf2+j, "\r\n");
sk_write(p->sub_socket, buf2, strlen(buf2));
}
sprintf(buf, "\r\n");
sk_write(p->sub_socket, buf, strlen(buf));
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.
*/
return plug_closing(p->plug, p->closing_error_msg,
p->closing_error_code,
p->closing_calling_back);
}
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_sock);
}
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;
int len;
int 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 = smalloc(len);
bufchain_fetch(&p->pending_input_data, data, len);
eol = get_line_end(data, len);
if (eol < 0) {
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[1024];
data[eol] = '\0';
while (eol > status &&
(data[eol-1] == '\r' || data[eol-1] == '\n'))
data[--eol] = '\0';
sprintf(buf, "Proxy error: %.900s",
data+status);
plug_closing(p->plug, buf, PROXY_ERROR_GENERAL, 0);
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 = smalloc(len);
datap = data;
bufchain_fetch(&p->pending_input_data, data, len);
eol = get_line_end(datap, len);
if (eol < 0) {
sfree(data);
return 1;
}
while (eol > 2)
{
bufchain_consume(&p->pending_input_data, eol);
datap += eol;
eol = get_line_end(datap, len);
}
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 (Proxy_Socket 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)
*/
int length;
char * command;
if (sk_addrtype(p->remote_addr) != AF_INET) {
plug_closing(p->plug, "Proxy error: SOCKS version 4 does"
" not support IPv6", PROXY_ERROR_GENERAL, 0);
return 1;
}
length = strlen(cfg.proxy_username) + 9;
command = (char*) malloc(length);
strcpy(command + 8, cfg.proxy_username);
command[0] = 4; /* version 4 */
command[1] = 1; /* CONNECT command */
/* port */
command[2] = (char) (p->remote_port >> 8) & 0xff;
command[3] = (char) p->remote_port & 0xff;
/* address */
sk_addrcopy(p->remote_addr, command + 4);
sk_write(p->sub_socket, command, length);
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.
*/
return plug_closing(p->plug, p->closing_error_msg,
p->closing_error_code,
p->closing_calling_back);
}
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_sock);
}
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 (Proxy_Socket 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
*/
char command[4];
int len;
command[0] = 5; /* version 5 */
if (cfg.proxy_username[0] || cfg.proxy_password[0]) {
command[1] = 2; /* two methods supported: */
command[2] = 0x00; /* no authentication */
command[3] = 0x02; /* username/password */
len = 4;
} else {
command[1] = 1; /* one methods supported: */
command[2] = 0x00; /* no authentication */
len = 3;
}
sk_write(p->sub_socket, command, len);
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.
*/
return plug_closing(p->plug, p->closing_error_msg,
p->closing_error_code,
p->closing_calling_back);
}
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_sock);
}
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 == 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]
*/
char command[22];
int len;
if (sk_addrtype(p->remote_addr) == AF_INET) {
len = 10;
command[3] = 1; /* IPv4 */
} else {
len = 22;
command[3] = 4; /* IPv6 */
}
command[0] = 5; /* version 5 */
command[1] = 1; /* CONNECT command */
command[2] = 0x00;
/* address */
sk_addrcopy(p->remote_addr, command+4);
/* port */
command[len-2] = (char) (p->remote_port >> 8) & 0xff;
command[len-1] = (char) p->remote_port & 0xff;
sk_write(p->sub_socket, command, len);
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 += (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) {
if (cfg.proxy_username[0] || cfg.proxy_password[0]) {
char userpwbuf[514];
int ulen, plen;
ulen = strlen(cfg.proxy_username);
if (ulen > 255) ulen = 255; if (ulen < 1) ulen = 1;
plen = strlen(cfg.proxy_password);
if (plen > 255) plen = 255; if (plen < 1) plen = 1;
userpwbuf[0] = 1; /* version number of subnegotiation */
userpwbuf[1] = ulen;
memcpy(userpwbuf+2, cfg.proxy_username, ulen);
userpwbuf[ulen+2] = plen;
memcpy(userpwbuf+ulen+3, cfg.proxy_password, plen);
sk_write(p->sub_socket, userpwbuf, ulen + plen + 3);
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) {
/* TODO: Handle CHAP authentication */
plug_closing(p->plug, "Proxy error: We don't support CHAP authentication",
PROXY_ERROR_GENERAL, 0);
return 1;
}
}
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.)
*/
int proxy_telnet_negotiate (Proxy_Socket p, int change)
{
if (p->state == PROXY_CHANGE_NEW) {
int so = 0, eo = 0;
/* we need to escape \\, \%, \r, \n, \t, \x??, \0???,
* %%, %host, and %port
*/
while (cfg.proxy_telnet_command[eo] != 0) {
/* scan forward until we hit end-of-line,
* or an escape character (\ or %) */
while (cfg.proxy_telnet_command[eo] != 0 &&
cfg.proxy_telnet_command[eo] != '%' &&
cfg.proxy_telnet_command[eo] != '\\') eo++;
/* if we hit eol, break out of our escaping loop */
if (cfg.proxy_telnet_command[eo] == 0) break;
/* if there was any unescaped text before the escape
* character, send that now */
if (eo != so) {
sk_write(p->sub_socket,
cfg.proxy_telnet_command + so, eo - so);
}
so = eo++;
/* if the escape character was the last character of
* the line, we'll just stop and send it. */
if (cfg.proxy_telnet_command[eo] == 0) break;
if (cfg.proxy_telnet_command[so] == '\\') {
/* we recognize \\, \%, \r, \n, \t, \x??.
* anything else, we just send unescaped (including the \).
*/
switch (cfg.proxy_telnet_command[eo]) {
case '\\':
sk_write(p->sub_socket, "\\", 1);
eo++;
break;
case '%':
sk_write(p->sub_socket, "%%", 1);
eo++;
break;
case 'r':
sk_write(p->sub_socket, "\r", 1);
eo++;
break;
case 'n':
sk_write(p->sub_socket, "\n", 1);
eo++;
break;
case 't':
sk_write(p->sub_socket, "\t", 1);
eo++;
break;
case 'x':
case 'X':
{
/* escaped hexadecimal value (ie. \xff) */
unsigned char v = 0;
int i = 0;
for (;;) {
eo++;
if (cfg.proxy_telnet_command[eo] >= '0' &&
cfg.proxy_telnet_command[eo] <= '9')
v += cfg.proxy_telnet_command[eo] - '0';
else if (cfg.proxy_telnet_command[eo] >= 'a' &&
cfg.proxy_telnet_command[eo] <= 'f')
v += cfg.proxy_telnet_command[eo] - 'a' + 10;
else if (cfg.proxy_telnet_command[eo] >= 'A' &&
cfg.proxy_telnet_command[eo] <= 'F')
v += cfg.proxy_telnet_command[eo] - 'A' + 10;
else {
/* non hex character, so we abort and just
* send the whole thing unescaped (including \x)
*/
sk_write(p->sub_socket, "\\", 1);
eo = so + 1;
break;
}
/* we only extract two hex characters */
if (i == 1) {
sk_write(p->sub_socket, &v, 1);
eo++;
break;
}
i++;
v <<= 4;
}
}
break;
default:
sk_write(p->sub_socket,
cfg.proxy_telnet_command + so, 2);
eo++;
break;
}
} else {
/* % escape. we recognize %%, %host, %port. anything else,
* we just send unescaped (including the %). */
if (cfg.proxy_telnet_command[eo] == '%') {
sk_write(p->sub_socket, "%", 1);
eo++;
}
else if (strnicmp(cfg.proxy_telnet_command + eo,
"host", 4) == 0) {
char dest[64];
sk_getaddr(p->remote_addr, dest, 64);
sk_write(p->sub_socket, dest, strlen(dest));
eo += 4;
}
else if (strnicmp(cfg.proxy_telnet_command + eo,
"port", 4) == 0) {
char port[8];
sprintf(port, "%i", p->remote_port);
sk_write(p->sub_socket, port, strlen(port));
eo += 4;
}
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.
*/
sk_write(p->sub_socket, "%", 1);
}
}
/* 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) {
sk_write(p->sub_socket, cfg.proxy_telnet_command + so, eo - so);
}
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.
*/
return plug_closing(p->plug, p->closing_error_msg,
p->closing_error_code,
p->closing_calling_back);
}
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_sock);
}
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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