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Try using OpenSSL directly
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David Woodhouse authored and David Woodhouse committed Sep 21, 2008
1 parent acdd15b commit 5d2e4c4
Showing 1 changed file with 224 additions and 46 deletions.
270 changes: 224 additions & 46 deletions cisco.c
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@@ -1,4 +1,5 @@
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
Expand All @@ -8,6 +9,14 @@
#include <net/if.h>
#include <sys/ioctl.h>
#include <linux/if_tun.h>
#include <openssl/ssl.h>
#include <sys/utsname.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

#define _GNU_SOURCE
#include <getopt.h>

#if 0
/* If the cookie expires, you can get another one by connecting with
Expand All @@ -23,31 +32,28 @@ X-Transcend-Version: 1

#endif

char request[] = "CONNECT /CSCOSSLC/tunnel HTTP/1.1\r\n"
"Host: vpnserver\r\n"
"User-Agent: Cisco AnyConnect VPN Agent for Windows 2.2.0\r\n"
"Cookie: webvpn=835267836@921600@1221512527@6BC73D90EB2F59E242F75B424D42F223D0912984\r\n"
"X-CSTP-Version: 1\r\n"
"X-CSTP-Hostname: macbook.infradead.org\r\n"
"X-CSTP-Accept-Encoding: xxdeflate;q=1.0\r\n"
"X-CSTP-MTU: 1406\r\n"
"X-CSTP-Address-Type: IPv6,IPv4\r\n"
"X-DTLS-Master-Secret: 5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A5A\r\n"
"X-DTLS-CipherSuite: AES256-SHA:AES128-SHA:DES-CBC3-SHA:DES-CBC-SHA\r\n\r\n";

/* The master-secret is generated randomly by the client. The server
responds with a DTLS Session-ID. These are enough to 'resume' the DTLS
session, bypassing all the initial setup of a normal DTLS connection.
Or you can just send traffic over the HTTPS connection... */

int main(int argc, char **argv)
struct cstp_option {
const char *option;
const char *value;
struct cstp_option *next;
};

char *cookie;
char *hostname;
unsigned char dtls_secret[48];
int mtu = 1406;
int deflate;
const char *useragent = "Cisco AnyConnect VPN Agent for Windows 2.2.0";
int verbose;

/* Set up a tuntap device. */
int setup_tun(struct cstp_option *options)
{
int in_pipes[2];
int out_pipes[2];
pid_t ssl_pid;
unsigned char buf[65536 + 8];
int buflen;
int state = 0;
struct ifreq ifr;
int tun_fd;

Expand All @@ -63,38 +69,210 @@ int main(int argc, char **argv)
perror("TUNSETIFF");
exit(1);
}
/* FIXME: Configure it... */
/* Better still, use lwip and just provide a SOCKS server rather than
telling the kernel at all */
return tun_fd;
}

SSL *open_https(const char *host)
{
SSL_METHOD *ssl3_method;
SSL_CTX *https_ctx;
SSL *https_ssl;
BIO *https_bio;
int ssl_sock;
int err;
struct addrinfo hints, *result, *rp;

memset(&hints, 0, sizeof(struct addrinfo));
hints.ai_family = AF_UNSPEC; /* Allow IPv4 or IPv6 */
hints.ai_socktype = SOCK_STREAM; /* Datagram socket */
hints.ai_flags = AI_PASSIVE; /* For wildcard IP address */
hints.ai_protocol = 0; /* Any protocol */
hints.ai_canonname = NULL;
hints.ai_addr = NULL;
hints.ai_next = NULL;

err = getaddrinfo(host, "https", &hints, &result);
if (err) {
fprintf(stderr, "getaddrinfo failed: %s\n", gai_strerror(err));
return NULL;
}

pipe(in_pipes);
pipe(out_pipes);
for (rp = result; rp ; rp = rp->ai_next) {
ssl_sock = socket(rp->ai_family, rp->ai_socktype,
rp->ai_protocol);
if (ssl_sock < 0)
continue;

ssl_pid = fork();
if (!ssl_pid) {
dup2(out_pipes[0], 0);
dup2(in_pipes[1], 1);
if (connect(ssl_sock, rp->ai_addr, rp->ai_addrlen) >= 0)
break;

close(in_pipes[0]);
close(in_pipes[1]);
close(out_pipes[0]);
close(out_pipes[1]);
execlp("openssl", "openssl", "s_client", "-quiet", "-connect", "vpnserver:443", NULL);
perror("exec");
exit(1);
close(ssl_sock);
}
freeaddrinfo(result);

if (!rp) {
fprintf(stderr, "Failed to connect to host %s\n", host);
return NULL;
}

ssl3_method = SSLv23_client_method();
https_ctx = SSL_CTX_new(ssl3_method);
https_ssl = SSL_new(https_ctx);

https_bio = BIO_new_socket(ssl_sock, BIO_NOCLOSE);
SSL_set_bio(https_ssl, https_bio, https_bio);

if (SSL_connect(https_ssl) <= 0) {
BIO *err_bio = BIO_new_fp(stderr, BIO_NOCLOSE);
fprintf(stderr, "SSL connection failure\n");
SSL_free(https_ssl);
SSL_CTX_free(https_ctx);
return NULL;
}

return https_ssl;
}

struct cstp_option *start_ssl_connection(SSL *ssl)
{
char buf[65536];
int i, state = 0;
struct cstp_option *options = NULL, **next_opt = &options;
struct utsname utsbuf;
BIO *bio = BIO_new(BIO_f_ssl());

BIO_set_ssl(bio, ssl, BIO_NOCLOSE);

if (uname(&utsbuf))
sprintf(utsbuf.nodename, "localhost");

if (verbose)
printf("Connected to HTTPS on %s\n", hostname);

BIO_printf(bio, "CONNECT /CSCOSSLC/tunnel HTTP/1.1\r\n");
BIO_printf(bio, "Host: %s\r\n", hostname);
BIO_printf(bio, "User-Agent: %S\r\n", useragent);
BIO_printf(bio, "Cookie: webvpn=%s\r\n", cookie);
BIO_printf(bio, "X-CSTP-Version: 1\r\n");
BIO_printf(bio, "X-CSTP-Hostname: %s\r\n", utsbuf.nodename);
if (deflate)
BIO_printf(bio, "X-CSTP-Accept-Encoding: deflate;q=1.0\r\n");
BIO_printf(bio, "X-CSTP-MTU: %d\r\n", mtu);
BIO_printf(bio, "X-CSTP-Address-Type: IPv6,IPv4\r\n");
BIO_printf(bio, "X-DTLS-Master-Secret: ");
for (i = 0; i < sizeof(dtls_secret); i++)
BIO_printf(bio, "%02X", dtls_secret[i]);
BIO_printf(bio, "X-DTLS-CipherSuite: AES256-SHA:AES128-SHA:DES-CBC3-SHA:DES-CBC-SHA\r\n\r\n");

state = 0;
#if 0
state = BIO_gets(bio, buf, sizeof(buf)-1);

if (state <= 0) {
fprintf(stderr, "Error getting HTTP CONNECT response: %d\n", state);
BIO_free(bio);
return NULL;
}
if (!strncmp(buf, "HTTP/1.1 200 ", 13)) {
fprintf(stderr, "Got inappropriate HTTP CONNECT response: %s\n",
buf);
BIO_free(bio);
return NULL;
}

while (BIO_gets(bio, buf, sizeof(buf)-1)) {
char *colon = strchr(buf, ':');

if (buf[strlen(buf)] == '\r') {
printf("ends \\r\n");
buf[strlen(buf)] = 0;
}

write(out_pipes[1], request, sizeof(request));
while (state < 4) {
read(in_pipes[0], buf, 1);
if ((state == 0 || state == 2) &&
buf[0] == '\r')
state++;
else if ((state == 1 || state == 3) &&
buf[0] == '\n')
state++;
else state = 0;
write(1, buf, 1);
if (!strlen(buf))
break;

fprintf(stderr, "Got: %s\n", buf);
}
#else
while (state < 4) {
SSL_read(ssl, buf, 1);
if ((state == 0 || state == 2) &&
buf[0] == '\r')
state++;
else if ((state == 1 || state == 3) &&
buf[0] == '\n')
state++;
else state = 0;
write(1, buf, 1);
}
#endif
return NULL;
}

static struct option long_options[] = {
{"cookie", 1, 0, 'c'},
{"host", 1, 0, 'h'},
{"mtu", 1, 0, 'm'},
};

int main(int argc, char **argv)
{
SSL *https_ssl;
struct cstp_option *opts;
int tun_fd;
int optind;
int opt;
char buf[65536 + 8];

SSL_library_init ();
ERR_clear_error ();
SSL_load_error_strings ();
OpenSSL_add_all_algorithms ();

while (opt = getopt_long(argc, argv, "c:h:", long_options, &optind)) {
if (opt < 0)
break;

switch (opt) {
case 'c':
cookie = optarg;
break;

case 'h':
hostname = optarg;
break;

case 'm':
mtu = atol(optarg);
if (mtu < 576) {
fprintf(stderr, "MTU %d too small\n", mtu);
exit(1);
}
break;
}
}
if (!hostname || !cookie) {
fprintf(stderr, "Need -h hostname, -c cookie\n");
exit(1);
}

https_ssl = open_https(hostname);
if (!https_ssl)
exit(1);
int i;
for (i=0; i<48; i++)
dtls_secret[i] = i;

opts = start_ssl_connection(https_ssl);

exit(1);
printf("Connected\n");

tun_fd = setup_tun(NULL);

if (fork()) {
while (1) {
size_t len;
Expand All @@ -113,15 +291,15 @@ int main(int argc, char **argv)
buf[4] = len >> 8;
buf[5] = len & 0xff;
}
write(out_pipes[1], buf, len + 8);
SSL_write(https_ssl, buf, len + 8);
}
} else {
while (1) {
int len;
read(in_pipes[0], buf, 8);
SSL_read(https_ssl, buf, 8);

len = (buf[4] << 8) + buf [5];
read(in_pipes[0], buf + 8, len);
SSL_read(https_ssl, buf + 8, len);
if (buf[0] != 'S' ||
buf[1] != 'T' ||
buf[2] != 'F' ||
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