GitHub CI: update list of container images
[tinc] / src / protocol_key.c
index a4d97ae..0890755 100644 (file)
@@ -1,7 +1,7 @@
 /*
     protocol_key.c -- handle the meta-protocol, key exchange
     Copyright (C) 1999-2005 Ivo Timmermans,
-                  2000-2013 Guus Sliepen <guus@tinc-vpn.org>
+                  2000-2017 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 "net.h"
 #include "netutl.h"
 #include "node.h"
-#include "prf.h"
 #include "protocol.h"
+#include "route.h"
 #include "sptps.h"
 #include "utils.h"
+#include "compression.h"
+#include "random.h"
 #include "xalloc.h"
 
-static bool mykeyused = false;
-
 void send_key_changed(void) {
-       send_request(everyone, "%d %x %s", KEY_CHANGED, rand(), myself->name);
+#ifndef DISABLE_LEGACY
+       send_request(everyone, "%d %x %s", KEY_CHANGED, prng(UINT32_MAX), myself->name);
 
        /* Immediately send new keys to directly connected nodes to keep UDP mappings alive */
 
-       for list_each(connection_t, c, connection_list)
-               if(c->edge && c->node && c->node->status.reachable && !c->node->status.sptps)
+       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)
+               for splay_each(node_t, n, &node_tree) {
+                       if(n->status.reachable && n->status.validkey && n->status.sptps) {
                                sptps_force_kex(&n->sptps);
+                       }
+               }
        }
 }
 
@@ -59,18 +66,19 @@ bool key_changed_h(connection_t *c, const char *request) {
 
        if(sscanf(request, "%*d %*x " MAX_STRING, name) != 1) {
                logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "KEY_CHANGED",
-                          c->name, c->hostname);
+                      c->name, c->hostname);
                return false;
        }
 
-       if(seen_request(request))
+       if(seen_request(request)) {
                return true;
+       }
 
        n = lookup_node(name);
 
        if(!n) {
                logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which does not exist",
-                          "KEY_CHANGED", c->name, c->hostname, name);
+                      "KEY_CHANGED", c->name, c->hostname, name);
                return true;
        }
 
@@ -81,17 +89,25 @@ bool key_changed_h(connection_t *c, const char *request) {
 
        /* Tell the others */
 
-       if(!tunnelserver)
+       if(!tunnelserver) {
                forward_request(c, request);
+       }
 
        return true;
 }
 
-static bool send_initial_sptps_data(void *handle, uint8_t type, const char *data, size_t len) {
+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) {
+       (void)type;
        node_t *to = handle;
-       to->sptps.send_data = send_sptps_data;
-       char buf[len * 4 / 3 + 5];
-       b64encode(data, buf, len);
+       to->sptps.send_data = send_sptps_data_myself;
+
+       char *buf = alloca(B64_SIZE(len));
+       b64encode_tinc(data, buf, len);
+
        return send_request(to->nexthop->connection, "%d %s %s %d %s", REQ_KEY, myself->name, to->name, REQ_KEY, buf);
 }
 
@@ -103,17 +119,16 @@ bool send_req_key(node_t *to) {
                        return true;
                }
 
-               if(to->sptps.label)
-                       logger(DEBUG_ALWAYS, LOG_DEBUG, "send_req_key(%s) called while sptps->label != NULL!", to->name);
+               const size_t labellen = 25 + strlen(myself->name) + strlen(to->name);
+               char *label = alloca(labellen);
+               snprintf(label, labellen, "tinc UDP key expansion %s %s", myself->name, to->name);
 
-               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 sptps_start(&to->sptps, to, true, true, myself->connection->ecdsa, to->ecdsa, label, labellen, send_initial_sptps_data, receive_sptps_record);
        }
 
        return send_request(to->nexthop->connection, "%d %s %s", REQ_KEY, myself->name, to->name);
@@ -121,85 +136,128 @@ bool send_req_key(node_t *to) {
 
 /* 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, int reqno) {
-       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);
+static bool req_key_ext_h(connection_t *c, const char *request, node_t *from, node_t *to, int reqno) {
+       (void)c;
+
+       /* 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];
+               size_t len;
+
+               if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode_tinc(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;
                }
 
-               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;
+               if(to != myself) {
+                       /* We don't just forward the request, because we want to use UDP if it's available. */
+                       if(forwarding_mode == FMODE_INTERNAL) {
+                               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);
+                               }
 
-                       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;
+                       send_mtu_info(myself, from, MTU);
                }
 
-               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;
-                       }
+               return true;
+       }
+
+       /* Requests that are not SPTPS data packets are forwarded as-is. */
 
-                       if(from->sptps.label)
-                               logger(DEBUG_ALWAYS, LOG_DEBUG, "Got REQ_KEY from %s while we already started a SPTPS session!", from->name);
+       if(to != myself) {
+               return send_request(to->nexthop->connection, "%s", request);
+       }
 
-                       char buf[MAX_STRING_SIZE];
-                       int len;
+       /* The request is for us */
 
-                       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;
-                       }
+       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 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, receive_sptps_record);
-                       sptps_receive_data(&from->sptps, buf, len);
+               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;
                }
 
-               case REQ_SPTPS: {
-                       if(!from->status.validkey) {
-                               logger(DEBUG_PROTOCOL, LOG_ERR, "Got REQ_SPTPS from %s (%s) but we don't have a valid key yet", from->name, from->hostname);
-                               return true;
-                       }
+               char pubkey[MAX_STRING_SIZE];
 
-                       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", from->name, from->hostname, "invalid SPTPS data");
-                               return true;
-                       }
-                       sptps_receive_data(&from->sptps, buf, len);
+               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;
                }
 
-               default:
-                       logger(DEBUG_ALWAYS, LOG_ERR, "Unknown extended REQ_KEY request from %s (%s): %s", from->name, from->hostname, request);
+               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];
+               size_t len;
+
+               if(sscanf(request, "%*d %*s %*s %*d " MAX_STRING, buf) != 1 || !(len = b64decode_tinc(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;
+               }
+
+               const size_t labellen = 25 + strlen(from->name) + strlen(myself->name);
+               char *label = alloca(labellen);
+               snprintf(label, labellen, "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, labellen, 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;
        }
 }
 
@@ -211,7 +269,7 @@ bool req_key_h(connection_t *c, const char *request) {
 
        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);
+                      c->hostname);
                return false;
        }
 
@@ -224,7 +282,7 @@ bool req_key_h(connection_t *c, const char *request) {
 
        if(!from) {
                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);
+                      "REQ_KEY", c->name, c->hostname, from_name);
                return true;
        }
 
@@ -232,30 +290,42 @@ bool req_key_h(connection_t *c, const char *request) {
 
        if(!to) {
                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);
+                      "REQ_KEY", c->name, c->hostname, to_name);
                return true;
        }
 
        /* Check if this key request is for us */
 
        if(to == myself) {                      /* Yes */
+               if(!from->status.reachable) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Got %s from %s (%s) origin %s which is not reachable",
+                              "REQ_KEY", c->name, c->hostname, from_name);
+                       return true;
+               }
+
                /* Is this an extended REQ_KEY message? */
-               if(experimental && reqno)
-                       return req_key_ext_h(c, request, from, reqno);
+               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)
+               if(tunnelserver) {
                        return true;
+               }
 
                if(!to->status.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);
+                              "REQ_KEY", c->name, c->hostname, to_name);
                        return true;
                }
 
-               /* TODO: forwarding SPTPS packets in this way is inefficient because we send them over TCP without checking for UDP connectivity */
+               /* 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);
        }
 
@@ -263,31 +333,49 @@ bool req_key_h(connection_t *c, const char *request) {
 }
 
 bool send_ans_key(node_t *to) {
-       if(to->status.sptps)
+       if(to->status.sptps) {
                abort();
+       }
 
+#ifdef DISABLE_LEGACY
+       return false;
+#else
        size_t keylen = myself->incipher ? cipher_keylength(myself->incipher) : 1;
-       char key[keylen * 2 + 1];
+       size_t keyhexlen = HEX_SIZE(keylen);
+       char *key = alloca(keyhexlen);
 
        randomize(key, keylen);
 
-       cipher_close(to->incipher);
-       digest_close(to->indigest);
+       cipher_free(to->incipher);
+       to->incipher = NULL;
+
+       digest_free(to->indigest);
+       to->indigest = NULL;
 
        if(myself->incipher) {
-               to->incipher = cipher_open_by_nid(cipher_get_nid(myself->incipher));
-               if(!to->incipher)
+               to->incipher = cipher_alloc();
+
+               if(!cipher_open_by_nid(to->incipher, cipher_get_nid(myself->incipher))) {
                        abort();
-               if(!cipher_set_key(to->incipher, key, false))
+               }
+
+               if(!cipher_set_key(to->incipher, key, false)) {
                        abort();
+               }
        }
 
        if(myself->indigest) {
-               to->indigest = digest_open_by_nid(digest_get_nid(myself->indigest), digest_length(myself->indigest));
-               if(!to->indigest)
+               to->indigest = digest_alloc();
+
+               if(!digest_open_by_nid(to->indigest,
+                                      digest_get_nid(myself->indigest),
+                                      digest_length(myself->indigest))) {
                        abort();
-               if(!digest_set_key(to->indigest, key, keylen))
+               }
+
+               if(!digest_set_key(to->indigest, key, keylen)) {
                        abort();
+               }
        }
 
        to->incompression = myself->incompression;
@@ -295,17 +383,26 @@ bool send_ans_key(node_t *to) {
        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 %d %d", ANS_KEY,
-                                               myself->name, to->name, key,
-                                               cipher_get_nid(to->incipher),
-                                               digest_get_nid(to->indigest),
-                                               (int)digest_length(to->indigest),
-                                               to->incompression);
+
+       if(replaywin) {
+               memset(to->late, 0, replaywin);
+       }
+
+       to->status.validkey_in = true;
+
+       bool sent = send_request(to->nexthop->connection, "%d %s %s %s %d %d %lu %d", ANS_KEY,
+                                myself->name, to->name, key,
+                                cipher_get_nid(to->incipher),
+                                digest_get_nid(to->indigest),
+                                (unsigned long)digest_length(to->indigest),
+                                to->incompression);
+
+       memzero(key, keyhexlen);
+
+       return sent;
+#endif
 }
 
 bool ans_key_h(connection_t *c, const char *request) {
@@ -314,14 +411,16 @@ bool ans_key_h(connection_t *c, const char *request) {
        char key[MAX_STRING_SIZE];
        char address[MAX_STRING_SIZE] = "";
        char port[MAX_STRING_SIZE] = "";
-       int cipher, digest, maclength, compression, keylen;
+       int cipher, digest;
+       unsigned long maclength;
+       int compression;
        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) {
+       if(sscanf(request, "%*d "MAX_STRING" "MAX_STRING" "MAX_STRING" %d %d %lu %d "MAX_STRING" "MAX_STRING,
+                       from_name, to_name, key, &cipher, &digest, &maclength,
+                       &compression, address, port) < 7) {
                logger(DEBUG_ALWAYS, LOG_ERR, "Got bad %s from %s (%s)", "ANS_KEY", c->name,
-                          c->hostname);
+                      c->hostname);
                return false;
        }
 
@@ -334,7 +433,7 @@ bool ans_key_h(connection_t *c, const char *request) {
 
        if(!from) {
                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);
+                      "ANS_KEY", c->name, c->hostname, from_name);
                return true;
        }
 
@@ -342,23 +441,24 @@ bool ans_key_h(connection_t *c, const char *request) {
 
        if(!to) {
                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);
+                      "ANS_KEY", c->name, c->hostname, to_name);
                return true;
        }
 
        /* Forward it if necessary */
 
        if(to != myself) {
-               if(tunnelserver)
+               if(tunnelserver) {
                        return true;
+               }
 
                if(!to->status.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);
+                              "ANS_KEY", c->name, c->hostname, to_name);
                        return true;
                }
 
-               if(!*address && from->address.sa.sa_family != AF_UNSPEC) {
+               if(!*address && from->address.sa.sa_family != AF_UNSPEC && to->minmtu) {
                        char *address, *port;
                        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);
@@ -371,13 +471,62 @@ bool ans_key_h(connection_t *c, const char *request) {
                return send_request(to->nexthop->connection, "%s", request);
        }
 
+#ifndef DISABLE_LEGACY
        /* Don't use key material until every check has passed. */
-       cipher_close(from->outcipher);
-       digest_close(from->outdigest);
-       from->status.validkey = false;
+       cipher_free(from->outcipher);
+       from->outcipher = NULL;
+
+       digest_free(from->outdigest);
+       from->outdigest = NULL;
+#endif
+
+       if(!from->status.sptps) {
+               from->status.validkey = false;
+       }
+
+       switch(compression) {
+       case COMPRESS_LZ4:
+#ifdef HAVE_LZ4
+               break;
+#else
+               logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
+               logger(DEBUG_ALWAYS, LOG_ERR, "LZ4 compression is unavailable on this node.");
+               return true;
+#endif
+
+       case COMPRESS_LZO_HI:
+       case COMPRESS_LZO_LO:
+#ifdef HAVE_LZO
+               break;
+#else
+               logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
+               logger(DEBUG_ALWAYS, LOG_ERR, "LZO compression is unavailable on this node.");
+               return true;
+#endif
+
+       case COMPRESS_ZLIB_9:
+       case COMPRESS_ZLIB_8:
+       case COMPRESS_ZLIB_7:
+       case COMPRESS_ZLIB_6:
+       case COMPRESS_ZLIB_5:
+       case COMPRESS_ZLIB_4:
+       case COMPRESS_ZLIB_3:
+       case COMPRESS_ZLIB_2:
+       case COMPRESS_ZLIB_1:
+#ifdef HAVE_ZLIB
+               break;
+#else
+               logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
+               logger(DEBUG_ALWAYS, LOG_ERR, "ZLIB compression is unavailable on this node.");
+               return true;
+#endif
+
+       case COMPRESS_NONE:
+               break;
 
-       if(compression < 0 || compression > 11) {
+       default:
                logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses bogus compression level!", from->name, from->hostname);
+               logger(DEBUG_ALWAYS, LOG_ERR, "Compression level %i is unrecognized by this node.", compression);
                return true;
        }
 
@@ -386,11 +535,23 @@ bool ans_key_h(connection_t *c, const char *request) {
        /* SPTPS or old-style key exchange? */
 
        if(from->status.sptps) {
-               char buf[strlen(key)];
-               int len = b64decode(key, buf, strlen(key));
+               const size_t buflen = strlen(key);
+               uint8_t *buf = alloca(buflen);
+               size_t len = b64decode_tinc(key, buf, buflen);
+
+               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);
+                       }
 
-               if(!len || !sptps_receive_data(&from->sptps, buf, len))
-                       logger(DEBUG_ALWAYS, LOG_ERR, "Error processing SPTPS data from %s (%s)", from->name, from->hostname);
+                       return true;
+               }
 
                if(from->status.validkey) {
                        if(*address && *port) {
@@ -398,18 +559,25 @@ bool ans_key_h(connection_t *c, const char *request) {
                                sockaddr_t sa = str2sockaddr(address, port);
                                update_node_udp(from, &sa);
                        }
-
-                       if(from->options & OPTION_PMTU_DISCOVERY && !(from->options & OPTION_TCPONLY))
-                               send_mtu_probe(from);
                }
 
+               send_mtu_info(myself, from, MTU);
+
                return true;
        }
 
+#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 */
 
        if(cipher) {
-               if(!(from->outcipher = cipher_open_by_nid(cipher))) {
+               from->outcipher = cipher_alloc();
+
+               if(!cipher_open_by_nid(from->outcipher, cipher)) {
+                       cipher_free(from->outcipher);
+                       from->outcipher = NULL;
                        logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown cipher!", from->name, from->hostname);
                        return false;
                }
@@ -418,7 +586,11 @@ bool ans_key_h(connection_t *c, const char *request) {
        }
 
        if(digest) {
-               if(!(from->outdigest = digest_open_by_nid(digest, maclength))) {
+               from->outdigest = digest_alloc();
+
+               if(!digest_open_by_nid(from->outdigest, digest, maclength)) {
+                       digest_free(from->outdigest);
+                       from->outdigest = NULL;
                        logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses unknown digest!", from->name, from->hostname);
                        return false;
                }
@@ -433,7 +605,7 @@ bool ans_key_h(connection_t *c, const char *request) {
 
        /* Process key */
 
-       keylen = hex2bin(key, key, sizeof key);
+       size_t keylen = hex2bin(key, key, sizeof(key));
 
        if(keylen != (from->outcipher ? cipher_keylength(from->outcipher) : 1)) {
                logger(DEBUG_ALWAYS, LOG_ERR, "Node %s (%s) uses wrong keylength!", from->name, from->hostname);
@@ -442,10 +614,13 @@ bool ans_key_h(connection_t *c, const char *request) {
 
        /* Update our copy of the origin's packet key */
 
-       if(from->outcipher && !cipher_set_key(from->outcipher, key, true))
+       if(from->outcipher && !cipher_set_key(from->outcipher, key, true)) {
                return false;
-       if(from->outdigest && !digest_set_key(from->outdigest, key, keylen))
+       }
+
+       if(from->outdigest && !digest_set_key(from->outdigest, key, keylen)) {
                return false;
+       }
 
        from->status.validkey = true;
        from->sent_seqno = 0;
@@ -456,8 +631,6 @@ bool ans_key_h(connection_t *c, const char *request) {
                update_node_udp(from, &sa);
        }
 
-       if(from->options & OPTION_PMTU_DISCOVERY && !(from->options & OPTION_TCPONLY))
-               send_mtu_probe(from);
-
        return true;
+#endif
 }