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proxy.c
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proxy.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(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 (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 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((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_write_eof (Socket s)
{
Proxy_Socket ps = (Proxy_Socket) s;
if (ps->state != PROXY_STATE_ACTIVE) {
ps->pending_eof = 1;
return;
}
sk_write_eof(ps->sub_socket);
}
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_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 void plug_proxy_log(Plug plug, int type, SockAddr addr, int port,
const char *error_msg, int error_code)
{
Proxy_Plug pp = (Proxy_Plug) plug;
Proxy_Socket ps = pp->proxy_socket;
plug_log(ps->plug, type, addr, port, error_msg, error_code);
}
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,
accept_fn_t constructor, accept_ctx_t ctx)
{
Proxy_Plug pp = (Proxy_Plug) p;
Proxy_Socket ps = pp->proxy_socket;
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.
*/
int 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 0; /* do not proxy */
/*
* Check the host name and IP against the hard-coded
* representations of `localhost'.
*/
if (!conf_get_int(conf, CONF_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 = 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)
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;
}
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, void *frontend,
const char *reason)
{
char *logmsg;
if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE &&
do_proxy_dns(conf) &&
proxy_for_destination(NULL, host, port, conf)) {
if (frontend) {
logmsg = dupprintf("Leaving host lookup to proxy of \"%s\""
" (for %s)", host, reason);
logevent(frontend, logmsg);
sfree(logmsg);
}
*canonicalname = dupstr(host);
return sk_nonamelookup(host);
} else {
if (frontend) {
logmsg = dns_log_msg(host, addressfamily, reason);
logevent(frontend, logmsg);
sfree(logmsg);
}
return sk_namelookup(host, canonicalname, addressfamily);
}
}
Socket new_connection(SockAddr addr, const char *hostname,
int port, int privport,
int oobinline, int nodelay, int keepalive,
Plug plug, Conf *conf)
{
static const struct socket_function_table socket_fn_table = {
sk_proxy_plug,
sk_proxy_close,
sk_proxy_write,
sk_proxy_write_oob,
sk_proxy_write_eof,
sk_proxy_flush,
sk_proxy_set_frozen,
sk_proxy_socket_error,
NULL, /* peer_info */
};
static const struct plug_function_table plug_fn_table = {
plug_proxy_log,
plug_proxy_closing,
plug_proxy_receive,
plug_proxy_sent,
plug_proxy_accepting
};
if (conf_get_int(conf, CONF_proxy_type) != PROXY_NONE &&
proxy_for_destination(addr, hostname, port, conf))
{
Proxy_Socket ret;
Proxy_Plug pplug;
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(struct Socket_proxy_tag);
ret->fn = &socket_fn_table;
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_flush = 0;
ret->pending_eof = 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;
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 (Socket) ret;
}
{
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, 2, NULL, 0, logmsg, 0);
sfree(logmsg);
}
/* 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;
{
char *logmsg = dns_log_msg(conf_get_str(conf, CONF_proxy_host),
conf_get_int(conf, CONF_addressfamily),
"proxy");
plug_log(plug, 2, 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";
sfree(pplug);
sk_addr_free(proxy_addr);
return (Socket)ret;
}
sfree(proxy_canonical_name);
{
char addrbuf[256], *logmsg;
sk_getaddr(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, 2, 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, (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(const char *srcaddr, int port, Plug plug,
int 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 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];
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.
*/
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_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;
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];
char *username;
type = sk_addrtype(p->remote_addr);
if (type == ADDRTYPE_IPV6) {
p->error = "Proxy error: SOCKS version 4 does not support IPv6";
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;
}
username = conf_get_str(p->conf, CONF_proxy_username);
length = strlen(username) + namelen + 9;
command = snewn(length, char);
strcpy(command + 8, 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(username) + 1,
hostname, namelen);
sk_write(p->sub_socket, command, length);
sfree(username);
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_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 (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];
char *username, *password;
int len;
command[0] = 5; /* version 5 */
username = conf_get_str(p->conf, CONF_proxy_username);
password = conf_get_str(p->conf, CONF_proxy_password);
if (username[0] || 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...
*/