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putty/proxy.c

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39 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>
#define DEFINE_PLUG_METHOD_MACROS
#include "putty.h"
#include "network.h"
#include "proxy.h"
#define do_proxy_dns(cfg) \
(cfg->proxy_dns == FORCE_ON || \
(cfg->proxy_dns == AUTO && \
cfg->proxy_type != PROXY_SOCKS4 && \
cfg->proxy_type != PROXY_SOCKS5))
/*
* 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;
long 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, 1);
/* 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) {
bufchain_prefix(&p->pending_oob_output_data, &data, &len);
output_after += sk_write_oob(p->sub_socket, data, len);
bufchain_consume(&p->pending_oob_output_data, len);
}
/* send buffered normal writes */
while (bufchain_size(&p->pending_output_data) > 0) {
bufchain_prefix(&p->pending_output_data, &data, &len);
output_after += sk_write(p->sub_socket, data, len);
bufchain_consume(&p->pending_output_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 were asked to flush the output during
* the proxy negotiation process, do so now.
*/
if (p->pending_flush) sk_flush(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((Socket)p, 0);
}
/* 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);
sk_addr_free(ps->remote_addr);
sfree(ps);
}
static int sk_proxy_write (Socket s, const 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, const 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;
}
/* 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) {
void *data;
char databuf[512];
int len;
bufchain_prefix(&ps->pending_input_data, &data, &len);
if (len > lenof(databuf))
len = lenof(databuf);
memcpy(databuf, data, len);
bufchain_consume(&ps->pending_input_data, len);
plug_receive(ps->plug, 0, databuf, 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)
{
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, const 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, OSSocket 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);
}
/*
* This function can accept a NULL pointer as `addr', in which case
* it will only check the host name.
*/
static int proxy_for_destination (SockAddr addr, char *hostname, int port,
const Config *cfg)
{
int s = 0, e = 0;
char hostip[64];
int hostip_len, hostname_len;
const char *exclude_list;
/*
* Check the host name and IP against the hard-coded
* representations of `localhost'.
*/
if (!cfg->even_proxy_localhost &&
(sk_hostname_is_local(hostname) ||
(addr && sk_address_is_local(addr))))
return 0; /* 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 = 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((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)
return 0; /* IP/hostname range excluded. do not use proxy. */
} 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)
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 (addr && strnicmp(hostip, exclude_list + s, e - s) == 0)
return 0; /* IP/hostname excluded. do not use proxy. */
if (strnicmp(hostname, exclude_list + s, e - s) == 0)
return 0; /* 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 1;
}
SockAddr name_lookup(char *host, int port, char **canonicalname,
const Config *cfg)
{
if (cfg->proxy_type != PROXY_NONE &&
do_proxy_dns(cfg) &&
proxy_for_destination(NULL, host, port, cfg)) {
*canonicalname = dupstr(host);
return sk_nonamelookup(host);
}
return sk_namelookup(host, canonicalname);
}
Socket new_connection(SockAddr addr, char *hostname,
int port, int privport,
int oobinline, int nodelay, int keepalive,
Plug plug, const Config *cfg)
{
static const 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 const 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, cfg))
{
Proxy_Socket ret;
Proxy_Plug pplug;
SockAddr proxy_addr;
char *proxy_canonical_name;
Socket sret;
if ((sret = platform_new_connection(addr, hostname, port, privport,
oobinline, nodelay, keepalive,
plug, cfg)) !=
NULL)
return sret;
ret = snew(struct Socket_proxy_tag);
ret->fn = &socket_fn_table;
ret->cfg = *cfg; /* STRUCTURE COPY */
ret->plug = plug;
ret->remote_addr = addr; /* will need to be freed on close */
ret->remote_port = port;
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;
ret->negotiate = NULL;
if (cfg->proxy_type == PROXY_HTTP) {
ret->negotiate = proxy_http_negotiate;
} else if (cfg->proxy_type == PROXY_SOCKS4) {
ret->negotiate = proxy_socks4_negotiate;
} else if (cfg->proxy_type == PROXY_SOCKS5) {
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 = snew(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);
if (sk_addr_error(proxy_addr) != NULL) {
ret->error = "Proxy error: Unable to resolve proxy host name";
return (Socket)ret;
}
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, keepalive, (Plug) pplug);
if (sk_socket_error(ret->sub_socket) != NULL)
return (Socket) ret;
/* 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, keepalive, plug);
}
Socket new_listener(char *srcaddr, int port, Plug plug, int local_host_only,
const Config *cfg)
{
/* TODO: SOCKS (and potentially others) support inbound
* TODO: connections via the proxy. support them.
*/
return sk_newlistener(srcaddr, 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, dest[512];
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);
if (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
char buf[sizeof(p->cfg.proxy_username)+sizeof(p->cfg.proxy_password)];
char buf2[sizeof(buf)*4/3 + 100];
int i, j, len;
sprintf(buf, "%s:%s", p->cfg.proxy_username, p->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((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));
}
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.
*/
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 = 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';
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;
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);
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;
len -= 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, type, namelen;
char *command, addr[4], hostname[512];
type = sk_addrtype(p->remote_addr);
if (type == ADDRTYPE_IPV6) {
plug_closing(p->plug, "Proxy error: SOCKS version 4 does"
" not support IPv6", PROXY_ERROR_GENERAL, 0);
return 1;
} else if (type == ADDRTYPE_IPV4) {
namelen = 0;
sk_addrcopy(p->remote_addr, addr);
} else { /* type == ADDRTYPE_NAME */
assert(type == ADDRTYPE_NAME);
sk_getaddr(p->remote_addr, hostname, lenof(hostname));
namelen = strlen(hostname) + 1; /* include the NUL */
addr[0] = addr[1] = addr[2] = 0;
addr[3] = 1;
}
length = strlen(p->cfg.proxy_username) + namelen + 9;
command = snewn(length, char);
strcpy(command + 8, p->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 */
memcpy(command + 4, addr, 4);
/* hostname */
memcpy(command + 8 + strlen(p->cfg.proxy_username) + 1,
hostname, namelen);
sk_write(p->sub_socket, command, length);
sfree(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[5];
int len;
command[0] = 5; /* version 5 */
if (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
command[2] = 0x00; /* no authentication */
len = 3;
proxy_socks5_offerencryptedauth (command, &len);
command[len++] = 0x02; /* username/password */
command[1] = len - 2; /* Number of methods supported */
} 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 == 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]
*/
char command[512];
int len;
int type;
type = sk_addrtype(p->remote_addr);
if (type == ADDRTYPE_IPV4) {
len = 10; /* 4 hdr + 4 addr + 2 trailer */
command[3] = 1; /* IPv4 */
sk_addrcopy(p->remote_addr, command+4);
} else if (type == ADDRTYPE_IPV6) {
len = 22; /* 4 hdr + 16 addr + 2 trailer */
command[3] = 4; /* IPv6 */
sk_addrcopy(p->remote_addr, command+4);
} else {
assert(type == ADDRTYPE_NAME);
command[3] = 3;
sk_getaddr(p->remote_addr, command+5, 256);
command[4] = strlen(command+5);
len = 7 + command[4]; /* 4 hdr, 1 len, N addr, 2 trailer */
}
command[0] = 5; /* version 5 */
command[1] = 1; /* CONNECT command */
command[2] = 0x00;
/* 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 (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
char userpwbuf[514];
int ulen, plen;
ulen = strlen(p->cfg.proxy_username);
if (ulen > 255) ulen = 255; if (ulen < 1) ulen = 1;
plen = strlen(p->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, p->cfg.proxy_username, ulen);
userpwbuf[ulen+2] = plen;
memcpy(userpwbuf+ulen+3, p->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) {
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, const Config *cfg)
{
char *ret = NULL;
int retlen = 0, retsize = 0;
int so = 0, eo = 0;
#define ENSURE(n) do { \
if (retsize < retlen + n) { \
retsize = retlen + n + 512; \
ret = sresize(ret, retsize, char); \
} \
} while (0)
/* we need to escape \\, \%, \r, \n, \t, \x??, \0???,
* %%, %host, %port, %user, and %pass
*/
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) {
ENSURE(eo - so);
memcpy(ret + retlen, cfg->proxy_telnet_command + so, eo - so);
retlen += 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 '\\':
ENSURE(1);
ret[retlen++] = '\\';
eo++;
break;
case '%':
ENSURE(1);
ret[retlen++] = '%';
eo++;
break;
case 'r':
ENSURE(1);
ret[retlen++] = '\r';
eo++;
break;
case 'n':
ENSURE(1);
ret[retlen++] = '\n';
eo++;
break;
case 't':
ENSURE(1);
ret[retlen++] = '\t';
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)
*/
ENSURE(1);
ret[retlen++] = '\\';
eo = so + 1;
break;
}
/* we only extract two hex characters */
if (i == 1) {
ENSURE(1);
ret[retlen++] = v;
eo++;
break;
}
i++;
v <<= 4;
}
}
break;
default:
ENSURE(2);
memcpy(ret+retlen, cfg->proxy_telnet_command + so, 2);
retlen += 2;
eo++;
break;
}
} else {
/* % escape. we recognize %%, %host, %port, %user, %pass.
* anything else, we just send unescaped (including the %).
*/
if (cfg->proxy_telnet_command[eo] == '%') {
ENSURE(1);
ret[retlen++] = '%';
eo++;
}
else if (strnicmp(cfg->proxy_telnet_command + eo,
"host", 4) == 0) {
char dest[512];
int destlen;
sk_getaddr(addr, dest, lenof(dest));
destlen = strlen(dest);
ENSURE(destlen);
memcpy(ret+retlen, dest, destlen);
retlen += destlen;
eo += 4;
}
else if (strnicmp(cfg->proxy_telnet_command + eo,
"port", 4) == 0) {
char portstr[8], portlen;
portlen = sprintf(portstr, "%i", port);
ENSURE(portlen);
memcpy(ret + retlen, portstr, portlen);
retlen += portlen;
eo += 4;
}
else if (strnicmp(cfg->proxy_telnet_command + eo,
"user", 4) == 0) {
int userlen = strlen(cfg->proxy_username);
ENSURE(userlen);
memcpy(ret+retlen, cfg->proxy_username, userlen);
retlen += userlen;
eo += 4;
}
else if (strnicmp(cfg->proxy_telnet_command + eo,
"pass", 4) == 0) {
int passlen = strlen(cfg->proxy_password);
ENSURE(passlen);
memcpy(ret+retlen, cfg->proxy_password, passlen);
retlen += passlen;
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.
*/
ENSURE(1);
ret[retlen++] = '%';
}
}
/* 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) {
ENSURE(eo - so);
memcpy(ret + retlen, cfg->proxy_telnet_command + so, eo - so);
retlen += eo - so;
}
ENSURE(1);
ret[retlen] = '\0';
return ret;
#undef ENSURE
}
int proxy_telnet_negotiate (Proxy_Socket p, int change)
{
if (p->state == PROXY_CHANGE_NEW) {
char *formatted_cmd;
formatted_cmd = format_telnet_command(p->remote_addr, p->remote_port,
&p->cfg);
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.
*/
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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