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FreeRDP/libfreerdp/core/proxy.c

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/**
* FreeRDP: A Remote Desktop Protocol Implementation
* HTTP Proxy support
*
* Copyright 2016 Christian Plattner <ccpp@gmx.at>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <ctype.h>
#include <errno.h>
#include "proxy.h"
#include "freerdp/settings.h"
#include "tcp.h"
#include "winpr/environment.h" /* For GetEnvironmentVariableA */
#define CRLF "\r\n"
#define TAG FREERDP_TAG("core.proxy")
/* SOCKS Proxy auth methods by rfc1928 */
enum
{
AUTH_M_NO_AUTH = 0,
AUTH_M_GSSAPI = 1,
AUTH_M_USR_PASS = 2
};
enum
{
SOCKS_CMD_CONNECT = 1,
SOCKS_CMD_BIND = 2,
SOCKS_CMD_UDP_ASSOCIATE = 3
};
enum
{
SOCKS_ADDR_IPV4 = 1,
SOCKS_ADDR_FQDN = 3,
SOCKS_ADDR_IPV6 = 4,
};
/* CONN REQ replies in enum. order */
static const char* rplstat[] = { "succeeded",
"general SOCKS server failure",
"connection not allowed by ruleset",
"Network unreachable",
"Host unreachable",
"Connection refused",
"TTL expired",
"Command not supported",
"Address type not supported" };
static BOOL http_proxy_connect(BIO* bufferedBio, const char* hostname, UINT16 port);
static BOOL socks_proxy_connect(BIO* bufferedBio, const char* proxyUsername,
const char* proxyPassword, const char* hostname, UINT16 port);
static void proxy_read_environment(rdpSettings* settings, char* envname);
static BOOL proxy_parse_uri(rdpSettings* settings, const char* uri);
BOOL proxy_prepare(rdpSettings* settings, const char** lpPeerHostname, UINT16* lpPeerPort,
const char** lpProxyUsername, const char** lpProxyPassword)
{
if (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType) == PROXY_TYPE_IGNORE)
return FALSE;
/* For TSGateway, find the system HTTPS proxy automatically */
if (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType) == PROXY_TYPE_NONE)
proxy_read_environment(settings, "https_proxy");
if (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType) == PROXY_TYPE_NONE)
proxy_read_environment(settings, "HTTPS_PROXY");
if (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType) != PROXY_TYPE_NONE)
proxy_read_environment(settings, "no_proxy");
if (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType) != PROXY_TYPE_NONE)
proxy_read_environment(settings, "NO_PROXY");
if (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType) != PROXY_TYPE_NONE)
{
*lpPeerHostname = freerdp_settings_get_string(settings, FreeRDP_ProxyHostname);
*lpPeerPort = freerdp_settings_get_uint16(settings, FreeRDP_ProxyPort);
*lpProxyUsername = freerdp_settings_get_string(settings, FreeRDP_ProxyUsername);
*lpProxyPassword = freerdp_settings_get_string(settings, FreeRDP_ProxyPassword);
return TRUE;
}
return FALSE;
}
static BOOL cidr4_match(const struct in_addr* addr, const struct in_addr* net, BYTE bits)
{
uint32_t mask, amask, nmask;
if (bits == 0)
return TRUE;
mask = htonl(0xFFFFFFFFu << (32 - bits));
amask = addr->s_addr & mask;
nmask = net->s_addr & mask;
return amask == nmask;
}
static BOOL cidr6_match(const struct in6_addr* address, const struct in6_addr* network,
uint8_t bits)
{
const uint32_t* a = (const uint32_t*)address;
const uint32_t* n = (const uint32_t*)network;
size_t bits_whole, bits_incomplete;
bits_whole = bits >> 5;
bits_incomplete = bits & 0x1F;
if (bits_whole)
{
if (memcmp(a, n, bits_whole << 2) != 0)
return FALSE;
}
if (bits_incomplete)
{
uint32_t mask = htonl((0xFFFFFFFFu) << (32 - bits_incomplete));
if ((a[bits_whole] ^ n[bits_whole]) & mask)
return FALSE;
}
return TRUE;
}
static BOOL check_no_proxy(rdpSettings* settings, const char* no_proxy)
{
const char* delimiter = ",";
BOOL result = FALSE;
char* current;
char* copy;
char* context = NULL;
size_t host_len;
struct sockaddr_in sa4;
struct sockaddr_in6 sa6;
BOOL is_ipv4 = FALSE;
BOOL is_ipv6 = FALSE;
if (!no_proxy || !settings)
return FALSE;
if (inet_pton(AF_INET, settings->ServerHostname, &sa4.sin_addr) == 1)
is_ipv4 = TRUE;
else if (inet_pton(AF_INET6, settings->ServerHostname, &sa6.sin6_addr) == 1)
is_ipv6 = TRUE;
host_len = strlen(settings->ServerHostname);
copy = _strdup(no_proxy);
if (!copy)
return FALSE;
current = strtok_s(copy, delimiter, &context);
while (current && !result)
{
const size_t currentlen = strlen(current);
if (currentlen > 0)
{
WLog_DBG(TAG, "%s => %s (%" PRIdz ")", settings->ServerHostname, current, currentlen);
/* detect left and right "*" wildcard */
if (current[0] == '*')
{
if (host_len >= currentlen)
{
const size_t offset = host_len + 1 - currentlen;
const char* name = settings->ServerHostname + offset;
if (strncmp(current + 1, name, currentlen - 1) == 0)
result = TRUE;
}
}
else if (current[currentlen - 1] == '*')
{
if (strncmp(current, settings->ServerHostname, currentlen - 1) == 0)
result = TRUE;
}
else if (current[0] ==
'.') /* Only compare if the no_proxy variable contains a whole domain. */
{
if (host_len > currentlen)
{
const size_t offset = host_len - currentlen;
const char* name = settings->ServerHostname + offset;
if (strncmp(current, name, currentlen) == 0)
result = TRUE; /* right-aligned match for host names */
}
}
else if (strcmp(current, settings->ServerHostname) == 0)
result = TRUE; /* exact match */
else if (is_ipv4 || is_ipv6)
{
char* rangedelim = strchr(current, '/');
/* Check for IP ranges */
if (rangedelim != NULL)
{
const char* range = rangedelim + 1;
int sub;
int rc = sscanf(range, "%u", &sub);
if ((rc == 1) && (rc >= 0))
{
*rangedelim = '\0';
if (is_ipv4)
{
struct sockaddr_in mask;
if (inet_pton(AF_INET, current, &mask.sin_addr))
result = cidr4_match(&sa4.sin_addr, &mask.sin_addr, sub);
}
else if (is_ipv6)
{
struct sockaddr_in6 mask;
if (inet_pton(AF_INET6, current, &mask.sin6_addr))
result = cidr6_match(&sa6.sin6_addr, &mask.sin6_addr, sub);
}
}
else
WLog_WARN(TAG, "NO_PROXY invalid entry %s", current);
}
else if (strncmp(current, settings->ServerHostname, currentlen) == 0)
result = TRUE; /* left-aligned match for IPs */
}
}
current = strtok_s(NULL, delimiter, &context);
}
free(copy);
return result;
}
void proxy_read_environment(rdpSettings* settings, char* envname)
{
DWORD envlen;
char* env;
envlen = GetEnvironmentVariableA(envname, NULL, 0);
if (!envlen)
return;
env = calloc(1, envlen);
if (!env)
{
WLog_ERR(TAG, "Not enough memory");
return;
}
if (GetEnvironmentVariableA(envname, env, envlen) == envlen - 1)
{
if (_strnicmp("NO_PROXY", envname, 9) == 0)
{
if (check_no_proxy(settings, env))
{
WLog_INFO(TAG, "deactivating proxy: %s [%s=%s]",
freerdp_settings_get_string(settings, FreeRDP_ServerHostname), envname,
env);
freerdp_settings_set_uint32(settings, FreeRDP_ProxyType, PROXY_TYPE_NONE);
}
}
else
{
proxy_parse_uri(settings, env);
}
}
free(env);
}
BOOL proxy_parse_uri(rdpSettings* settings, const char* uri_in)
{
BOOL rc = FALSE;
char *hostname, *pport;
const char* protocol;
char* p;
UINT16 port;
char* uri_copy = _strdup(uri_in);
char* uri = uri_copy;
if (!uri)
return FALSE;
p = strstr(uri, "://");
if (p)
{
if (p == uri + 4 && !strncmp("http", uri, 4))
{
if (!freerdp_settings_set_uint32(settings, FreeRDP_ProxyType, PROXY_TYPE_HTTP))
goto fail;
protocol = "http";
}
else if (p == uri + 6 && !strncmp("socks5", uri, 6))
{
if (!freerdp_settings_set_uint32(settings, FreeRDP_ProxyType, PROXY_TYPE_SOCKS))
goto fail;
protocol = "socks5";
}
else
{
WLog_ERR(TAG, "Only HTTP and SOCKS5 proxies supported by now");
goto fail;
}
uri = p + 3;
}
else
{
WLog_ERR(TAG, "No scheme in proxy URI");
goto fail;
}
hostname = uri;
pport = strchr(hostname, ':');
if (pport)
{
long val;
errno = 0;
val = strtol(pport + 1, NULL, 0);
if ((errno != 0) || (val <= 0) || (val > UINT16_MAX))
return FALSE;
port = (UINT16)val;
}
else
{
/* The default is 80. Also for Proxys. */
port = 80;
pport = strchr(hostname, '/');
}
if (pport)
*pport = '\0';
if (!freerdp_settings_set_string(settings, FreeRDP_ProxyHostname, hostname))
goto fail;
if (!freerdp_settings_set_uint16(settings, FreeRDP_ProxyPort, port))
goto fail;
WLog_INFO(TAG, "Parsed proxy configuration: %s://%s:%d", protocol,
freerdp_settings_get_string(settings, FreeRDP_ProxyHostname),
freerdp_settings_get_uint16(settings, FreeRDP_ProxyPort));
rc = TRUE;
fail:
free(uri_copy);
return rc;
}
BOOL proxy_connect(rdpSettings* settings, BIO* bufferedBio, const char* proxyUsername,
const char* proxyPassword, const char* hostname, UINT16 port)
{
switch (freerdp_settings_get_uint32(settings, FreeRDP_ProxyType))
{
case PROXY_TYPE_NONE:
case PROXY_TYPE_IGNORE:
return TRUE;
case PROXY_TYPE_HTTP:
return http_proxy_connect(bufferedBio, hostname, port);
case PROXY_TYPE_SOCKS:
return socks_proxy_connect(bufferedBio, proxyUsername, proxyPassword, hostname, port);
default:
WLog_ERR(TAG, "Invalid internal proxy configuration");
return FALSE;
}
}
static const char* get_response_header(char* response)
{
char* current_pos = strchr(response, '\r');
if (!current_pos)
current_pos = strchr(response, '\n');
if (current_pos)
*current_pos = '\0';
return response;
}
static BOOL http_proxy_connect(BIO* bufferedBio, const char* hostname, UINT16 port)
{
int status;
wStream* s;
char port_str[10], recv_buf[256], *eol;
size_t resultsize;
_itoa_s(port, port_str, sizeof(port_str), 10);
s = Stream_New(NULL, 200);
Stream_Write(s, "CONNECT ", 8);
Stream_Write(s, hostname, strlen(hostname));
Stream_Write_UINT8(s, ':');
Stream_Write(s, port_str, strlen(port_str));
Stream_Write(s, " HTTP/1.1" CRLF "Host: ", 17);
Stream_Write(s, hostname, strlen(hostname));
Stream_Write_UINT8(s, ':');
Stream_Write(s, port_str, strnlen(port_str, sizeof(port_str)));
Stream_Write(s, CRLF CRLF, 4);
status = BIO_write(bufferedBio, Stream_Buffer(s), Stream_GetPosition(s));
if ((status < 0) || ((size_t)status != Stream_GetPosition(s)))
{
Stream_Free(s, TRUE);
WLog_ERR(TAG, "HTTP proxy: failed to write CONNECT request");
return FALSE;
}
Stream_Free(s, TRUE);
s = NULL;
/* Read result until CR-LF-CR-LF.
* Keep recv_buf a null-terminated string. */
memset(recv_buf, '\0', sizeof(recv_buf));
resultsize = 0;
while (strstr(recv_buf, CRLF CRLF) == NULL)
{
if (resultsize >= sizeof(recv_buf) - 1)
{
WLog_ERR(TAG, "HTTP Reply headers too long: %s", get_response_header(recv_buf));
return FALSE;
}
status =
BIO_read(bufferedBio, (BYTE*)recv_buf + resultsize, sizeof(recv_buf) - resultsize - 1);
if (status < 0)
{
/* Error? */
if (BIO_should_retry(bufferedBio))
{
USleep(100);
continue;
}
WLog_ERR(TAG, "Failed reading reply from HTTP proxy (Status %d)", status);
return FALSE;
}
else if (status == 0)
{
/* Error? */
WLog_ERR(TAG, "Failed reading reply from HTTP proxy (BIO_read returned zero)");
return FALSE;
}
resultsize += status;
}
/* Extract HTTP status line */
eol = strchr(recv_buf, '\r');
if (!eol)
{
/* should never happen */
return FALSE;
}
*eol = '\0';
WLog_INFO(TAG, "HTTP Proxy: %s", recv_buf);
if (strnlen(recv_buf, sizeof(recv_buf)) < 12)
{
return FALSE;
}
recv_buf[7] = 'X';
if (strncmp(recv_buf, "HTTP/1.X 200", 12))
return FALSE;
return TRUE;
}
static int recv_socks_reply(BIO* bufferedBio, BYTE* buf, int len, char* reason, BYTE checkVer)
{
int status;
for (;;)
{
status = BIO_read(bufferedBio, buf, len);
if (status > 0)
{
break;
}
else if (status < 0)
{
/* Error? */
if (BIO_should_retry(bufferedBio))
{
USleep(100);
continue;
}
WLog_ERR(TAG, "Failed reading %s reply from SOCKS proxy (Status %d)", reason, status);
return -1;
}
else // if (status == 0)
{
/* Error? */
WLog_ERR(TAG, "Failed reading %s reply from SOCKS proxy (BIO_read returned zero)",
reason);
return -1;
}
}
if (status < 2)
{
WLog_ERR(TAG, "SOCKS Proxy reply packet too short (%s)", reason);
return -1;
}
if (buf[0] != checkVer)
{
WLog_ERR(TAG, "SOCKS Proxy version is not 5 (%s)", reason);
return -1;
}
return status;
}
static BOOL socks_proxy_connect(BIO* bufferedBio, const char* proxyUsername,
const char* proxyPassword, const char* hostname, UINT16 port)
{
int status;
int nauthMethods = 1, writeLen = 3;
BYTE buf[3 + 255 + 255]; /* biggest packet is user/pass auth */
size_t hostnlen = strnlen(hostname, 255);
if (proxyUsername && proxyPassword)
{
nauthMethods++;
writeLen++;
}
/* select auth. method */
buf[0] = 5; /* SOCKS version */
buf[1] = nauthMethods; /* #of methods offered */
buf[2] = AUTH_M_NO_AUTH;
if (nauthMethods > 1)
buf[3] = AUTH_M_USR_PASS;
status = BIO_write(bufferedBio, buf, writeLen);
if (status != writeLen)
{
WLog_ERR(TAG, "SOCKS proxy: failed to write AUTH METHOD request");
return FALSE;
}
status = recv_socks_reply(bufferedBio, buf, 2, "AUTH REQ", 5);
if (status <= 0)
return FALSE;
switch (buf[1])
{
case AUTH_M_NO_AUTH:
WLog_DBG(TAG, "SOCKS Proxy: (NO AUTH) method was selected");
break;
case AUTH_M_USR_PASS:
if (!proxyUsername || !proxyPassword)
return FALSE;
else
{
int usernameLen = strnlen(proxyUsername, 255);
int userpassLen = strnlen(proxyPassword, 255);
BYTE* ptr;
if (nauthMethods < 2)
{
WLog_ERR(TAG, "SOCKS Proxy: USER/PASS method was not proposed to server");
return FALSE;
}
/* user/password v1 method */
ptr = buf + 2;
buf[0] = 1;
buf[1] = usernameLen;
memcpy(ptr, proxyUsername, usernameLen);
ptr += usernameLen;
*ptr = userpassLen;
ptr++;
memcpy(ptr, proxyPassword, userpassLen);
status = BIO_write(bufferedBio, buf, 3 + usernameLen + userpassLen);
if (status != 3 + usernameLen + userpassLen)
{
WLog_ERR(TAG, "SOCKS Proxy: error writing user/password request");
return FALSE;
}
status = recv_socks_reply(bufferedBio, buf, 2, "AUTH REQ", 1);
if (status < 2)
return FALSE;
if (buf[1] != 0x00)
{
WLog_ERR(TAG, "SOCKS Proxy: invalid user/password");
return FALSE;
}
}
break;
default:
WLog_ERR(TAG, "SOCKS Proxy: unknown method 0x%x was selected by proxy", buf[1]);
return FALSE;
}
/* CONN request */
buf[0] = 5; /* SOCKS version */
buf[1] = SOCKS_CMD_CONNECT; /* command */
buf[2] = 0; /* 3rd octet is reserved x00 */
buf[3] = SOCKS_ADDR_FQDN; /* addr.type */
buf[4] = hostnlen; /* DST.ADDR */
memcpy(buf + 5, hostname, hostnlen);
/* follows DST.PORT in netw. format */
buf[hostnlen + 5] = (port >> 8) & 0xff;
buf[hostnlen + 6] = port & 0xff;
status = BIO_write(bufferedBio, buf, hostnlen + 7U);
if ((status < 0) || ((size_t)status != (hostnlen + 7U)))
{
WLog_ERR(TAG, "SOCKS proxy: failed to write CONN REQ");
return FALSE;
}
status = recv_socks_reply(bufferedBio, buf, sizeof(buf), "CONN REQ", 5);
if (status < 4)
return FALSE;
if (buf[1] == 0)
{
WLog_INFO(TAG, "Successfully connected to %s:%d", hostname, port);
return TRUE;
}
if (buf[1] > 0 && buf[1] < 9)
WLog_INFO(TAG, "SOCKS Proxy replied: %s", rplstat[buf[1]]);
else
WLog_INFO(TAG, "SOCKS Proxy replied: %d status not listed in rfc1928", buf[1]);
return FALSE;
}
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