tinc-gui: Reformat codebase according to PEP8
[tinc] / src / protocol_key.c
index 313681b..b409a35 100644 (file)
@@ -1,7 +1,7 @@
 /*
     protocol_key.c -- handle the meta-protocol, key exchange
     Copyright (C) 1999-2005 Ivo Timmermans,
-                  2000-2011 Guus Sliepen <guus@tinc-vpn.org>
+                  2000-2014 Guus Sliepen <guus@tinc-vpn.org>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
 
 #include "system.h"
 
-#include "splay_tree.h"
 #include "cipher.h"
 #include "connection.h"
 #include "crypto.h"
-#include "ecdh.h"
 #include "logger.h"
 #include "net.h"
 #include "netutl.h"
 #include "node.h"
 #include "prf.h"
 #include "protocol.h"
+#include "sptps.h"
 #include "utils.h"
 #include "xalloc.h"
 
 static bool mykeyused = false;
 
 void send_key_changed(void) {
-       splay_node_t *node;
-       connection_t *c;
-
-       send_request(broadcast, "%d %x %s", KEY_CHANGED, rand(), myself->name);
+#ifndef DISABLE_LEGACY
+       send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
 
        /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
 
-       for(node = connection_tree->head; node; node = node->next) {
-               c = node->data;
-               if(c->status.active && c->node && c->node->status.reachable)
+       for list_each(connection_t, c, connection_list)
+               if(c->edge && c->node && c->node->status.reachable && !c->node->status.sptps)
                        send_ans_key(c->node);
+#endif
+
+       /* Force key exchange for connections using SPTPS */
+
+       if(experimental) {
+               for splay_each(node_t, n, node_tree)
+                       if(n->status.reachable && n->status.validkey && n->status.sptps)
+                               sptps_force_kex(&n->sptps);
        }
 }
 
-bool key_changed_h(connection_t *c, char *request) {
+bool key_changed_h(connection_t *c, const char *request) {
        char name[MAX_STRING_SIZE];
        node_t *n;
 
        if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
-               logger(LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
                           c->name, c->hostname);
                return false;
        }
@@ -67,13 +71,15 @@ bool key_changed_h(connection_t *c, char *request) {
        n = lookup_node(name);
 
        if(!n) {
-               logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
                           "KEY_CHANGED", c->name, c->hostname, name);
                return true;
        }
 
-       n->status.validkey = false;
-       n->last_req_key = 0;
+       if(!n->status.sptps) {
+               n->status.validkey = false;
+               n->last_req_key = 0;
+       }
 
        /* Tell the others */
 
@@ -83,31 +89,174 @@ bool key_changed_h(connection_t *c, char *request) {
        return true;
 }
 
+static bool send_sptps_data_myself(void *handle, uint8_t type, const void *data, size_t len) {
+       return send_sptps_data(handle, myself, type, data, len);
+}
+
+static bool send_initial_sptps_data(void *handle, uint8_t type, const void *data, size_t len) {
+       node_t *to = handle;
+       to->sptps.send_data = send_sptps_data_myself;
+       char buf[len * 4 / 3 + 5];
+       b64encode(data, buf, len);
+       return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
+}
+
 bool send_req_key(node_t *to) {
-       return send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, experimental ? 1 : 0);
+       if(to->status.sptps) {
+               if(!node_read_ecdsa_public_key(to)) {
+                       logger(DEBUG_PROTOCOL, LOG_DEBUG, "No Ed25519 key known for %s (%s)", to->name, to->hostname);
+                       send_request(to->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, to->name, REQ_PUBKEY);
+                       return true;
+               }
+
+               char label[25 + strlen(myself->name) + strlen(to->name)];
+               snprintf(label, sizeof label, "tinc UDP key expansion %s %s", myself->name, to->name);
+               sptps_stop(&to->sptps);
+               to->status.validkey = false;
+               to->status.waitingforkey = true;
+               to->last_req_key = now.tv_sec;
+               to->incompression = myself->incompression;
+               return sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, sizeof label, send_initial_sptps_data, receive_sptps_record);
+       }
+
+       return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
+}
+
+/* REQ_KEY is overloaded to allow arbitrary requests to be routed between two nodes. */
+
+static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, node_t *to, int reqno) {
+       /* If this is a SPTPS packet, see if sending UDP info helps.
+          Note that we only do this if we're the destination or the static relay;
+          otherwise every hop would initiate its own UDP info message, resulting in elevated chatter. */
+       if((reqno == REQ_KEY || reqno == SPTPS_PACKET) && to->via == myself)
+               send_udp_info(myself, from);
+
+       if(reqno == SPTPS_PACKET) {
+               /* This is a SPTPS data packet. */
+
+               char buf[MAX_STRING_SIZE];
+               int len;
+               if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s) to %s (%s): %s", "SPTPS_PACKET", from->name, from->hostname, to->name, to->hostname, "invalid SPTPS data");
+                       return true;
+               }
+
+               if(to != myself) {
+                       /* We don't just forward the request, because we want to use UDP if it's available. */
+                       send_sptps_data(to, from, 0, buf, len);
+                       try_tx(to, true);
+               } else {
+                       /* The packet is for us */
+                       if(!sptps_receive_data(&from->sptps, buf, len)) {
+                               /* Uh-oh. It might be that the tunnel is stuck in some corrupted state,
+                                  so let's restart SPTPS in case that helps. But don't do that too often
+                                  to prevent storms. */
+                               if(from->last_req_key < now.tv_sec - 10) {
+                                       logger(DEBUG_PROTOCOL, LOG_ERR, "Failed to decode TCP packet from %s (%s), restarting SPTPS", from->name, from->hostname);
+                                       send_req_key(from);
+                               }
+                               return true;
+                       }
+                       send_mtu_info(myself, from, MTU);
+               }
+
+               return true;
+       }
+
+       /* Requests that are not SPTPS data packets are forwarded as-is. */
+
+       if (to != myself)
+               return send_request(to->nexthop->connection, "%s", request);
+
+       /* The request is for us */
+
+       switch(reqno) {
+               case REQ_PUBKEY: {
+                       if(!node_read_ecdsa_public_key(from)) {
+                               /* Request their key *before* we send our key back. Otherwise the first SPTPS packet from them will get dropped. */
+                               logger(DEBUG_PROTOCOL, LOG_DEBUG, "Preemptively requesting Ed25519 key for %s (%s)", from->name, from->hostname);
+                               send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
+                       }
+                       char *pubkey = ecdsa_get_base64_public_key(myself->connection->ecdsa);
+                       send_request(from->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, from->name, ANS_PUBKEY, pubkey);
+                       free(pubkey);
+                       return true;
+               }
+
+               case ANS_PUBKEY: {
+                       if(node_read_ecdsa_public_key(from)) {
+                               logger(DEBUG_PROTOCOL, LOG_WARNING, "Got ANS_PUBKEY from %s (%s) even though we already have his pubkey", from->name, from->hostname);
+                               return true;
+                       }
+
+                       char pubkey[MAX_STRING_SIZE];
+                       if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, pubkey) != 1 || !(from->ecdsa = ecdsa_set_base64_public_key(pubkey))) {
+                               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_PUBKEY", from->name, from->hostname, "invalid pubkey");
+                               return true;
+                       }
+
+                       logger(DEBUG_PROTOCOL, LOG_INFO, "Learned Ed25519 public key from %s (%s)", from->name, from->hostname);
+                       append_config_file(from->name, "Ed25519PublicKey", pubkey);
+                       return true;
+               }
+
+               case REQ_KEY: {
+                       if(!node_read_ecdsa_public_key(from)) {
+                               logger(DEBUG_PROTOCOL, LOG_DEBUG, "No Ed25519 key known for %s (%s)", from->name, from->hostname);
+                               send_request(from->nexthop->connection, "%d %s %s %d", REQ_KEY, myself->name, from->name, REQ_PUBKEY);
+                               return true;
+                       }
+
+                       if(from->sptps.label)
+                               logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
+
+                       char buf[MAX_STRING_SIZE];
+                       int len;
+
+                       if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode(buf, buf, strlen(buf)))) {
+                               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_SPTPS_START", from->name, from->hostname, "invalid SPTPS data");
+                               return true;
+                       }
+
+                       char label[25 + strlen(from->name) + strlen(myself->name)];
+                       snprintf(label, sizeof label, "tinc UDP key expansion %s %s", from->name, myself->name);
+                       sptps_stop(&from->sptps);
+                       from->status.validkey = false;
+                       from->status.waitingforkey = true;
+                       from->last_req_key = now.tv_sec;
+                       sptps_start(&from->sptps, from, false, true, myself->connection->ecdsa, from->ecdsa, label, sizeof label, send_sptps_data_myself, receive_sptps_record);
+                       sptps_receive_data(&from->sptps, buf, len);
+                       send_mtu_info(myself, from, MTU);
+                       return true;
+               }
+
+               default:
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
+                       return true;
+       }
 }
 
-bool req_key_h(connection_t *c, char *request) {
+bool req_key_h(connection_t *c, const char *request) {
        char from_name[MAX_STRING_SIZE];
        char to_name[MAX_STRING_SIZE];
        node_t *from, *to;
-       int kx_version = 0;
+       int reqno = 0;
 
-       if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &kx_version) < 2) {
-               logger(LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
+       if(sscanf(request, "%*d " MAX_STRING " " MAX_STRING " %d", from_name, to_name, &reqno) < 2) {
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "REQ_KEY", c->name,
                           c->hostname);
                return false;
        }
 
        if(!check_id(from_name) || !check_id(to_name)) {
-               logger(LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "REQ_KEY", c->name, c->hostname, "invalid name");
                return false;
        }
 
        from = lookup_node(from_name);
 
        if(!from) {
-               logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
                           "REQ_KEY", c->name, c->hostname, from_name);
                return true;
        }
@@ -115,106 +264,118 @@ bool req_key_h(connection_t *c, char *request) {
        to = lookup_node(to_name);
 
        if(!to) {
-               logger(LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
                           "REQ_KEY", c->name, c->hostname, to_name);
                return true;
        }
 
        /* Check if this key request is for us */
 
-       if(to == myself) {                      /* Yes, send our own key back */
-               if(experimental && kx_version >= 1) {
-                       logger(LOG_DEBUG, "Got ECDH key request from %s", from->name);
-                       from->status.ecdh = true;
-               }
+       if(to == myself) {                      /* Yes */
+               /* Is this an extended REQ_KEY message? */
+               if(experimental && reqno)
+                       return req_key_ext_h(c, request, from, to, reqno);
+
+               /* No, just send our key back */
                send_ans_key(from);
        } else {
                if(tunnelserver)
                        return true;
 
                if(!to->status.reachable) {
-                       logger(LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
+                       logger(DEBUG_PROTOCOL, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
                                "REQ_KEY", c->name, c->hostname, to_name);
                        return true;
                }
 
+               /* Is this an extended REQ_KEY message? */
+               if(experimental && reqno)
+                       return req_key_ext_h(c, request, from, to, reqno);
+
                send_request(to->nexthop->connection, "%s", request);
        }
 
        return true;
 }
 
-bool send_ans_key_ecdh(node_t *to) {
-       char key[ECDH_SIZE * 2 + 1];
+bool send_ans_key(node_t *to) {
+       if(to->status.sptps)
+               abort();
 
-       ecdh_generate_public(&to->ecdh, key);
+#ifdef DISABLE_LEGACY
+       return false;
+#else
+       size_t keylen = myself->incipher ? cipher_keylength(myself->incipher) : 1;
+       char key[keylen * 2 + 1];
 
-       b64encode(key, key, ECDH_SIZE);
+       randomize(key, keylen);
 
-       return send_request(to->nexthop->connection, "%d %s %s ECDH:%s %d %d %zu %d", ANS_KEY,
-                                               myself->name, to->name, key,
-                                               cipher_get_nid(&myself->incipher),
-                                               digest_get_nid(&myself->indigest),
-                                               digest_length(&myself->indigest),
-                                               myself->incompression);
-}
+       cipher_close(to->incipher);
+       digest_close(to->indigest);
 
-bool send_ans_key(node_t *to) {
-       if(experimental && to->status.ecdh)
-               return send_ans_key_ecdh(to);
+       if(myself->incipher) {
+               to->incipher = cipher_open_by_nid(cipher_get_nid(myself->incipher));
+               if(!to->incipher)
+                       abort();
+               if(!cipher_set_key(to->incipher, key, false))
+                       abort();
+       }
 
-       size_t keylen = cipher_keylength(&myself->incipher);
-       char key[keylen * 2 + 1];
+       if(myself->indigest) {
+               to->indigest = digest_open_by_nid(digest_get_nid(myself->indigest), digest_length(myself->indigest));
+               if(!to->indigest)
+                       abort();
+               if(!digest_set_key(to->indigest, key, keylen))
+                       abort();
+       }
 
-       cipher_open_by_nid(&to->incipher, cipher_get_nid(&myself->incipher));
-       digest_open_by_nid(&to->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
        to->incompression = myself->incompression;
 
-       randomize(key, keylen);
-       cipher_set_key(&to->incipher, key, false);
-       digest_set_key(&to->indigest, key, keylen);
-
        bin2hex(key, key, keylen);
 
        // Reset sequence number and late packet window
        mykeyused = true;
        to->received_seqno = 0;
+       to->received = 0;
        if(replaywin) memset(to->late, 0, replaywin);
 
-       return send_request(to->nexthop->connection, "%d %s %s %s %d %d %zu %d", ANS_KEY,
+       to->status.validkey_in = true;
+
+       return send_request(to->nexthop->connection, "%d %s %s %s %d %d %d %d", ANS_KEY,
                                                myself->name, to->name, key,
-                                               cipher_get_nid(&to->incipher),
-                                               digest_get_nid(&to->indigest),
-                                               digest_length(&to->indigest),
+                                               cipher_get_nid(to->incipher),
+                                               digest_get_nid(to->indigest),
+                                               (int)digest_length(to->indigest),
                                                to->incompression);
+#endif
 }
 
-bool ans_key_h(connection_t *c, char *request) {
+bool ans_key_h(connection_t *c, const char *request) {
        char from_name[MAX_STRING_SIZE];
        char to_name[MAX_STRING_SIZE];
        char key[MAX_STRING_SIZE];
-        char address[MAX_STRING_SIZE] = "";
-        char port[MAX_STRING_SIZE] = "";
+       char address[MAX_STRING_SIZE] = "";
+       char port[MAX_STRING_SIZE] = "";
        int cipher, digest, maclength, compression, keylen;
        node_t *from, *to;
 
        if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %d %d "MAX_STRING" "MAX_STRING,
                from_name, to_name, key, &cipher, &digest, &maclength,
                &compression, address, port) < 7) {
-               logger(LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
                           c->hostname);
                return false;
        }
 
        if(!check_id(from_name) || !check_id(to_name)) {
-               logger(LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s): %s", "ANS_KEY", c->name, c->hostname, "invalid name");
                return false;
        }
 
        from = lookup_node(from_name);
 
        if(!from) {
-               logger(LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist in our connection list",
                           "ANS_KEY", c->name, c->hostname, from_name);
                return true;
        }
@@ -222,7 +383,7 @@ bool ans_key_h(connection_t *c, char *request) {
        to = lookup_node(to_name);
 
        if(!to) {
-               logger(LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
+               logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) destination %s which does not exist in our connection list",
                           "ANS_KEY", c->name, c->hostname, to_name);
                return true;
        }
@@ -234,14 +395,14 @@ bool ans_key_h(connection_t *c, char *request) {
                        return true;
 
                if(!to->status.reachable) {
-                       logger(LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
+                       logger(DEBUG_ALWAYS, LOG_WARNING, "Got %s from %s (%s) destination %s which is not reachable",
                                   "ANS_KEY", c->name, c->hostname, to_name);
                        return true;
                }
 
                if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
                        char *address, *port;
-                       ifdebug(PROTOCOL) logger(LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
+                       logger(DEBUG_PROTOCOL, LOG_DEBUG, "Appending reflexive UDP address to ANS_KEY from %s to %s", from->name, to->name);
                        sockaddr2str(&from->address, &address, &port);
                        send_request(to->nexthop->connection, "%s %s %s", request, address, port);
                        free(address);
@@ -252,123 +413,105 @@ bool ans_key_h(connection_t *c, char *request) {
                return send_request(to->nexthop->connection, "%s", request);
        }
 
-       /* Check and lookup cipher and digest algorithms */
-
-       if(!cipher_open_by_nid(&from->outcipher, cipher)) {
-               logger(LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
-               return false;
-       }
-
-       if(!digest_open_by_nid(&from->outdigest, digest, maclength)) {
-               logger(LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
-               return false;
-       }
-
-       if(maclength != digest_length(&from->outdigest)) {
-               logger(LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
-               return false;
-       }
+#ifndef DISABLE_LEGACY
+       /* Don't use key material until every check has passed. */
+       cipher_close(from->outcipher);
+       digest_close(from->outdigest);
+#endif
+       from->status.validkey = false;
 
        if(compression < 0 || compression > 11) {
-               logger(LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
+               logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
                return true;
        }
 
        from->outcompression = compression;
 
-       /* ECDH or old-style key exchange? */
-       
-       if(experimental && !strncmp(key, "ECDH:", 5)) {
-               int keylen = b64decode(key + 5, key + 5, sizeof key - 5);
-
-               if(keylen != ECDH_SIZE) {
-                       logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
-                       return false;
-               }
-
-               if(ECDH_SHARED_SIZE < cipher_keylength(&from->outcipher)) {
-                       logger(LOG_ERR, "ECDH key too short for cipher of %s!", from->name);
-                       return false;
+       /* SPTPS or old-style key exchange? */
+
+       if(from->status.sptps) {
+               char buf[strlen(key)];
+               int len = b64decode(key, buf, strlen(key));
+               if(!len || !sptps_receive_data(&from->sptps, buf, len)) {
+                       /* Uh-oh. It might be that the tunnel is stuck in some corrupted state,
+                          so let's restart SPTPS in case that helps. But don't do that too often
+                          to prevent storms.
+                          Note that simply relying on handshake timeout is not enough, because
+                          that doesn't apply to key regeneration. */
+                       if(from->last_req_key < now.tv_sec - 10) {
+                               logger(DEBUG_PROTOCOL, LOG_ERR, "Failed to decode handshake TCP packet from %s (%s), restarting SPTPS", from->name, from->hostname);
+                               send_req_key(from);
+                       }
+                       return true;
                }
 
-               if(!from->ecdh) {
-                       from->status.ecdh = true;
-                       if(!send_ans_key(from))
-                               return false;
+               if(from->status.validkey) {
+                       if(*address && *port) {
+                               logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
+                               sockaddr_t sa = str2sockaddr(address, port);
+                               update_node_udp(from, &sa);
+                       }
                }
 
-               char shared[ECDH_SHARED_SIZE * 2 + 1];
-
-               if(!ecdh_compute_shared(&from->ecdh, key + 5, shared))
-                       return false;
+               send_mtu_info(myself, from, MTU);
 
-               /* Update our crypto end */
+               return true;
+       }
 
-               size_t mykeylen = cipher_keylength(&myself->incipher);
-               size_t hiskeylen = cipher_keylength(&from->outcipher);
+#ifdef DISABLE_LEGACY
+       logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses legacy protocol!", from->name, from->hostname);
+       return false;
+#else
+       /* Check and lookup cipher and digest algorithms */
 
-               char *mykey;
-               char *hiskey;
-               char *seed;
-               
-               if(strcmp(myself->name, from->name) < 0) {
-                       mykey = key;
-                       hiskey = key + mykeylen * 2;
-                       xasprintf(&seed, "tinc UDP key expansion %s %s", myself->name, from->name);
-               } else {
-                       mykey = key + hiskeylen * 2;
-                       hiskey = key;
-                       xasprintf(&seed, "tinc UDP key expansion %s %s", from->name, myself->name);
+       if(cipher) {
+               if(!(from->outcipher = cipher_open_by_nid(cipher))) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
+                       return false;
                }
+       } else {
+               from->outcipher = NULL;
+       }
 
-               if(!prf(shared, ECDH_SHARED_SIZE, seed, strlen(seed), key, hiskeylen * 2 + mykeylen * 2))
+       if(digest) {
+               if(!(from->outdigest = digest_open_by_nid(digest, maclength))) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
                        return false;
+               }
+       } else {
+               from->outdigest = NULL;
+       }
 
-               free(seed);
-
-               cipher_open_by_nid(&from->incipher, cipher_get_nid(&myself->incipher));
-               digest_open_by_nid(&from->indigest, digest_get_nid(&myself->indigest), digest_length(&myself->indigest));
-               from->incompression = myself->incompression;
-
-               cipher_set_key(&from->incipher, mykey, false);
-               digest_set_key(&from->indigest, mykey + mykeylen, mykeylen);
-
-               cipher_set_key(&from->outcipher, hiskey, true);
-               digest_set_key(&from->outdigest, hiskey + hiskeylen, hiskeylen);
+       if(maclength != digest_length(from->outdigest)) {
+               logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus MAC length!", from->name, from->hostname);
+               return false;
+       }
 
-               // Reset sequence number and late packet window
-               mykeyused = true;
-               from->received_seqno = 0;
-               if(replaywin)
-                       memset(from->late, 0, replaywin);
+       /* Process key */
 
-               if(strcmp(myself->name, from->name) < 0)
-                       memmove(key, key + mykeylen * 2, hiskeylen * 2);
-       } else {
-               keylen = hex2bin(key, key, sizeof key);
+       keylen = hex2bin(key, key, sizeof key);
 
-               if(keylen != cipher_keylength(&from->outcipher)) {
-                       logger(LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
-                       return false;
-               }
+       if(keylen != (from->outcipher ? cipher_keylength(from->outcipher) : 1)) {
+               logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
+               return true;
+       }
 
-               /* Update our copy of the origin's packet key */
+       /* Update our copy of the origin's packet key */
 
-               cipher_set_key(&from->outcipher, key, true);
-               digest_set_key(&from->outdigest, key, keylen);
-       }
+       if(from->outcipher && !cipher_set_key(from->outcipher, key, true))
+               return false;
+       if(from->outdigest && !digest_set_key(from->outdigest, key, keylen))
+               return false;
 
        from->status.validkey = true;
        from->sent_seqno = 0;
 
        if(*address && *port) {
-               ifdebug(PROTOCOL) logger(LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
+               logger(DEBUG_PROTOCOL, LOG_DEBUG, "Using reflexive UDP address from %s: %s port %s", from->name, address, port);
                sockaddr_t sa = str2sockaddr(address, port);
                update_node_udp(from, &sa);
        }
 
-       if(from->options & OPTION_PMTU_DISCOVERY)
-               send_mtu_probe(from);
-
        return true;
+#endif
 }