/*
This file is part of GNUnet.
- Copyright (C) 2009, 2015 Christian Grothoff (and other contributing authors)
+ Copyright (C) 2009, 2015 GNUnet e.V.
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
You should have received a copy of the GNU General Public License
along with GNUnet; see the file COPYING. If not, write to the
- Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA.
+ Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ Boston, MA 02110-1301, USA.
*/
-
/**
- * This code is based on ministun.c, that is based on Asterisk old STUN code.
* This code provides some support for doing STUN transactions.
- * The simplest request packet is just the header defined in
- * struct stun_header, and from the response we may just look at
- * one attribute, STUN_MAPPED_ADDRESS, that we find in the response.
- * By doing more transactions with different server addresses we
- * may determine more about the behaviour of the NAT boxes, of
- * course - the details are in the RFC.
+ * We send simplest possible packet ia REQUEST with BIND to a STUN server.
*
* All STUN packets start with a simple header made of a type,
* length (excluding the header) and a 16-byte random transaction id.
* on the type, but often contains addresses).
* Of course all fields are in network format.
*
+ * This code was based on ministun.c.
*
* @file nat/nat_stun.c
- * @brief Testcase for STUN library
+ * @brief Functions for STUN functionality
* @author Bruno Souza Cabral
*/
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_resolver_service.h"
+#include "gnunet_nat_lib.h"
+
+
+#include "nat_stun.h"
+
+#define LOG(kind,...) GNUNET_log_from (kind, "stun", __VA_ARGS__)
+
+#define TIMEOUT GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 15)
+
+
+/**
+ * Handle to a request given to the resolver. Can be used to cancel
+ * the request prior to the timeout or successful execution. Also
+ * used to track our internal state for the request.
+ */
+struct GNUNET_NAT_STUN_Handle
+{
+
+ /**
+ * Handle to a pending DNS lookup request.
+ */
+ struct GNUNET_RESOLVER_RequestHandle *dns_active;
+
+ /**
+ * Handle to the listen socket
+ */
+ struct GNUNET_NETWORK_Handle *sock;
+
+ /**
+ * Stun server address
+ */
+ char *stun_server;
+
+ /**
+ * Function to call when a error occours
+ */
+ GNUNET_NAT_STUN_ErrorCallback cb;
+
+ /**
+ * Closure for @e cb.
+ */
+ void *cb_cls;
+
+ /**
+ * Do we got a DNS resolution successfully?
+ */
+ int dns_success;
+
+ /**
+ * STUN port
+ */
+ uint16_t stun_port;
+
+};
+
+
+/**
+ * here we store credentials extracted from a message
+*/
+struct StunState
+{
+ uint16_t attr;
+};
+
+
+/**
+ * Convert a message to a StunClass
+ *
+ * @param msg the received message
+ * @return the converted StunClass
+ */
+static int
+decode_class(int msg)
+{
+ /* Sorry for the magic, but this maps the class according to rfc5245 */
+ return ((msg & 0x0010) >> 4) | ((msg & 0x0100) >> 7);
+}
+
+/**
+ * Convert a message to a StunMethod
+ *
+ * @param msg the received message
+ * @return the converted StunMethod
+ */
+static int
+decode_method(int msg)
+{
+ return (msg & 0x000f) | ((msg & 0x00e0) >> 1) | ((msg & 0x3e00) >> 2);
+}
+
+
+/**
+ * Encode a class and method to a compatible STUN format
+ *
+ * @param msg_class class to be converted
+ * @param method method to be converted
+ * @return message in a STUN compatible format
+ */
+static int
+encode_message (enum StunClasses msg_class,
+ enum StunMethods method)
+{
+ return ((msg_class & 1) << 4) | ((msg_class & 2) << 7) |
+ (method & 0x000f) | ((method & 0x0070) << 1) | ((method & 0x0f800) << 2);
+}
+
+
+/**
+ * Print a class and method from a STUN message
+ *
+ * @param msg
+ * @return string with the message class and method
+ */
+static const char *
+stun_msg2str(int msg)
+{
+ static const struct {
+ enum StunClasses value;
+ const char *name;
+ } classes[] = {
+ { STUN_REQUEST, "Request" },
+ { STUN_INDICATION, "Indication" },
+ { STUN_RESPONSE, "Response" },
+ { STUN_ERROR_RESPONSE, "Error Response" },
+ { 0, NULL }
+ };
+ static const struct {
+ enum StunMethods value;
+ const char *name;
+ } methods[] = {
+ { STUN_BINDING, "Binding" },
+ { 0, NULL }
+ };
+ static char result[32];
+ const char *msg_class = NULL;
+ const char *method = NULL;
+ int i;
+ int value;
+
+ value = decode_class(msg);
+ for (i = 0; classes[i].name; i++)
+ {
+ msg_class = classes[i].name;
+ if (classes[i].value == value)
+ break;
+ }
+ value = decode_method(msg);
+ for (i = 0; methods[i].name; i++)
+ {
+ method = methods[i].name;
+ if (methods[i].value == value)
+ break;
+ }
+ GNUNET_snprintf (result,
+ sizeof(result),
+ "%s %s",
+ method ? : "Unknown Method",
+ msg_class ? : "Unknown Class Message");
+ return result;
+}
+
+
+/**
+ * Print attribute name
+ *
+ * @param msg with a attribute type
+ * @return string with the attribute name
+ */
+static const char *
+stun_attr2str (int msg)
+{
+ static const struct {
+ enum StunAttributes value;
+ const char *name;
+ } attrs[] = {
+ { STUN_MAPPED_ADDRESS, "Mapped Address" },
+ { STUN_RESPONSE_ADDRESS, "Response Address" },
+ { STUN_CHANGE_ADDRESS, "Change Address" },
+ { STUN_SOURCE_ADDRESS, "Source Address" },
+ { STUN_CHANGED_ADDRESS, "Changed Address" },
+ { STUN_USERNAME, "Username" },
+ { STUN_PASSWORD, "Password" },
+ { STUN_MESSAGE_INTEGRITY, "Message Integrity" },
+ { STUN_ERROR_CODE, "Error Code" },
+ { STUN_UNKNOWN_ATTRIBUTES, "Unknown Attributes" },
+ { STUN_REFLECTED_FROM, "Reflected From" },
+ { STUN_REALM, "Realm" },
+ { STUN_NONCE, "Nonce" },
+ { STUN_XOR_MAPPED_ADDRESS, "XOR Mapped Address" },
+ { STUN_MS_VERSION, "MS Version" },
+ { STUN_MS_XOR_MAPPED_ADDRESS, "MS XOR Mapped Address" },
+ { STUN_SOFTWARE, "Software" },
+ { STUN_ALTERNATE_SERVER, "Alternate Server" },
+ { STUN_FINGERPRINT, "Fingerprint" },
+ { 0, NULL }
+ };
+ unsigned int i;
+
+ for (i = 0; attrs[i].name; i++)
+ {
+ if (attrs[i].value == msg)
+ return attrs[i].name;
+ }
+ return "Unknown Attribute";
+}
+
+
+/**
+ * Fill the stun_header with a random request_id
+ *
+ * @param req, stun header to be filled
+ */
+static void
+generate_request_id (struct stun_header *req)
+{
+ unsigned int x;
+
+ req->magic = htonl(STUN_MAGIC_COOKIE);
+ for (x = 0; x < 3; x++)
+ req->id.id[x] = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
+ UINT32_MAX);
+}
+
+
+/**
+ * Extract the STUN_MAPPED_ADDRESS from the stun response.
+ * This is used as a callback for stun_handle_response
+ * when called from stun_request.
+ *
+ * @param st, pointer where we will set the type
+ * @param attr , received stun attribute
+ * @param arg , pointer to a sockaddr_in where we will set the reported IP and port
+ * @param magic , Magic cookie
+ *
+ * @return 0 on success, other value otherwise
+ */
+static int
+stun_get_mapped (struct StunState *st,
+ struct stun_attr *attr,
+ struct sockaddr_in *arg,
+ unsigned int magic)
+{
+ struct stun_addr *returned_addr = (struct stun_addr *)(attr + 1);
+ struct sockaddr_in *sa = (struct sockaddr_in *)arg;
+ unsigned short type = ntohs(attr->attr);
+
+ switch (type)
+ {
+ case STUN_MAPPED_ADDRESS:
+ if (st->attr == STUN_XOR_MAPPED_ADDRESS ||
+ st->attr == STUN_MS_XOR_MAPPED_ADDRESS)
+ return 1;
+ magic = 0;
+ break;
+ case STUN_MS_XOR_MAPPED_ADDRESS:
+ if (st->attr == STUN_XOR_MAPPED_ADDRESS)
+ return 1;
+ break;
+ case STUN_XOR_MAPPED_ADDRESS:
+ break;
+ default:
+ return 1;
+ }
+ if ( (ntohs(attr->len) < 8) &&
+ (returned_addr->family != 1) )
+ {
+ return 1;
+ }
+ st->attr = type;
+ sa->sin_family = AF_INET;
+ sa->sin_port = returned_addr->port ^ htons(ntohl(magic) >> 16);
+ sa->sin_addr.s_addr = returned_addr->addr ^ magic;
+ return 0;
+}
+
+
+/**
+ * Handle an incoming STUN message, Do some basic sanity checks on packet size and content,
+ * try to extract a bit of information, and possibly reply.
+ * At the moment this only processes BIND requests, and returns
+ * the externally visible address of the request.
+ * If a callback is specified, invoke it with the attribute.
+ *
+ * @param data the packet
+ * @param len the length of the packet in @a data
+ * @param[out] arg sockaddr_in where we will set our discovered address
+ *
+ * @return, #GNUNET_OK on OK, #GNUNET_NO if the packet is invalid (not a stun packet)
+ */
+int
+GNUNET_NAT_stun_handle_packet (const void *data,
+ size_t len,
+ struct sockaddr_in *arg)
+{
+ const struct stun_header *hdr = (const struct stun_header *)data;
+ struct stun_attr *attr;
+ struct StunState st;
+ int ret = GNUNET_OK;
+ uint32_t advertised_message_size;
+ uint32_t message_magic_cookie;
+
+ /* On entry, 'len' is the length of the udp payload. After the
+ * initial checks it becomes the size of unprocessed options,
+ * while 'data' is advanced accordingly.
+ */
+ if (len < sizeof(struct stun_header))
+ {
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "STUN packet too short (only %d, wanting at least %d)\n",
+ (int) len,
+ (int) sizeof(struct stun_header));
+ GNUNET_break_op (0);
+ return GNUNET_NO;
+ }
+ /* Skip header as it is already in hdr */
+ len -= sizeof(struct stun_header);
+ data += sizeof(struct stun_header);
+
+ /* len as advertised in the message */
+ advertised_message_size = ntohs(hdr->msglen);
+
+ message_magic_cookie = ntohl(hdr->magic);
+ /* Compare if the cookie match */
+ if (STUN_MAGIC_COOKIE != message_magic_cookie)
+ {
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "Invalid magic cookie \n");
+ return GNUNET_NO;
+ }
+
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "STUN Packet, msg %s (%04x), length: %d\n",
+ stun_msg2str(ntohs(hdr->msgtype)),
+ ntohs(hdr->msgtype),
+ advertised_message_size);
+ if (advertised_message_size > len)
+ {
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "Scrambled STUN packet length (got %d, expecting %d)\n",
+ advertised_message_size,
+ (int)len);
+ return GNUNET_NO;
+ }
+ len = advertised_message_size;
+ memset (&st, 0, sizeof(st));
+
+ while (len > 0)
+ {
+ if (len < sizeof(struct stun_attr))
+ {
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "Attribute too short (got %d, expecting %d)\n",
+ (int)len,
+ (int) sizeof(struct stun_attr));
+ break;
+ }
+ attr = (struct stun_attr *)data;
+
+ /* compute total attribute length */
+ advertised_message_size = ntohs(attr->len) + sizeof(struct stun_attr);
+
+ /* Check if we still have space in our buffer */
+ if (advertised_message_size > len )
+ {
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "Inconsistent Attribute (length %d exceeds remaining msg len %d)\n",
+ advertised_message_size,
+ (int)len);
+ break;
+ }
+ stun_get_mapped (&st,
+ attr,
+ arg,
+ hdr->magic);
+ /* Clear attribute id: in case previous entry was a string,
+ * this will act as the terminator for the string.
+ */
+ attr->attr = 0;
+ data += advertised_message_size;
+ len -= advertised_message_size;
+ ret = GNUNET_OK;
+ }
+ return ret;
+}
+
+
+/**
+ * Cancel active STUN request. Frees associated resources
+ * and ensures that the callback is no longer invoked.
+ *
+ * @param rh request to cancel
+ */
+void
+GNUNET_NAT_stun_make_request_cancel (struct GNUNET_NAT_STUN_Handle *rh)
+{
+ if (NULL != rh->dns_active)
+ {
+ GNUNET_RESOLVER_request_cancel (rh->dns_active);
+ rh->dns_active = NULL;
+ }
+ GNUNET_free (rh->stun_server);
+ GNUNET_free (rh);
+}
+
+
+/**
+ * Try to establish a connection given the specified address.
+ *
+ * @param cls our `struct GNUNET_NAT_STUN_Handle *`
+ * @param addr address to try, NULL for "last call"
+ * @param addrlen length of @a addr
+ */
+static void
+stun_dns_callback (void *cls,
+ const struct sockaddr *addr,
+ socklen_t addrlen)
+{
+ struct GNUNET_NAT_STUN_Handle *rh = cls;
+ struct stun_header *req;
+ uint8_t reqdata[1024];
+ int reqlen;
+ struct sockaddr_in server;
+
+ rh->dns_active = NULL;
+ if (NULL == addr)
+ {
+ if (GNUNET_NO == rh->dns_success)
+ {
+ LOG (GNUNET_ERROR_TYPE_INFO,
+ "Error resolving host %s\n",
+ rh->stun_server);
+ rh->cb (rh->cb_cls,
+ GNUNET_NAT_ERROR_NOT_ONLINE);
+ GNUNET_NAT_stun_make_request_cancel (rh);
+ }
+ return;
+ }
+
+ rh->dns_success = GNUNET_YES;
+ memset (&server,0, sizeof(server));
+ server.sin_family = AF_INET;
+ server.sin_addr = ((struct sockaddr_in *)addr)->sin_addr;
+ server.sin_port = htons(rh->stun_port);
+#if HAVE_SOCKADDR_IN_SIN_LEN
+ server.sin_len = (u_char) sizeof (struct sockaddr_in);
+#endif
+
+ /*Craft the simplest possible STUN packet. A request binding*/
+ req = (struct stun_header *)reqdata;
+ generate_request_id(req);
+ reqlen = 0;
+ req->msgtype = 0;
+ req->msglen = 0;
+ req->msglen = htons(reqlen);
+ req->msgtype = htons(encode_message(STUN_REQUEST, STUN_BINDING));
+
+ /* Send the packet */
+ if (-1 == GNUNET_NETWORK_socket_sendto (rh->sock,
+ req,
+ ntohs(req->msglen) + sizeof(*req),
+ (const struct sockaddr *) &server,
+ sizeof (server)))
+ {
+ GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
+ "Fail to sendto");
+ rh->cb (rh->cb_cls,
+ GNUNET_NAT_ERROR_INTERNAL_NETWORK_ERROR);
+ GNUNET_NAT_stun_make_request_cancel (rh);
+ return;
+ }
+ /* sending STUN request done, let's wait for replies... */
+ rh->cb (rh->cb_cls,
+ GNUNET_NAT_ERROR_SUCCESS);
+ GNUNET_NAT_stun_make_request_cancel (rh);
+}
+
+
+/**
+ * Make Generic STUN request. Sends a generic stun request to the
+ * server specified using the specified socket, possibly waiting for
+ * a reply and filling the 'reply' field with the externally visible
+ * address.
+ *
+ * @param server the address of the stun server
+ * @param port port of the stun server
+ * @param sock the socket used to send the request
+ * @param cb callback in case of error
+ * @param cb_cls closure for @a cb
+ * @return NULL on error
+ */
+struct GNUNET_NAT_STUN_Handle *
+GNUNET_NAT_stun_make_request (const char *server,
+ uint16_t port,
+ struct GNUNET_NETWORK_Handle *sock,
+ GNUNET_NAT_STUN_ErrorCallback cb,
+ void *cb_cls)
+{
+ struct GNUNET_NAT_STUN_Handle *rh;
+
+ rh = GNUNET_new (struct GNUNET_NAT_STUN_Handle);
+ rh->sock = sock;
+ rh->cb = cb;
+ rh->cb_cls = cb_cls;
+ rh->stun_server = GNUNET_strdup (server);
+ rh->stun_port = port;
+ rh->dns_success = GNUNET_NO;
+ rh->dns_active = GNUNET_RESOLVER_ip_get (rh->stun_server,
+ AF_INET,
+ TIMEOUT,
+ &stun_dns_callback, rh);
+ if (NULL == rh->dns_active)
+ {
+ GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
+ "Failed DNS");
+ GNUNET_NAT_stun_make_request_cancel (rh);
+ return NULL;
+ }
+ return rh;
+}
+
+/* end of nat_stun.c */