[Openvpn-devel,v10] multipeer: introduce asymmetric peer-id

diff --git a/src/openvpn/dco.c b/src/openvpn/dco.c
index 6a1a5c9..0dd19de 100644
--- a/src/openvpn/dco.c
+++ b/src/openvpn/dco.c
@@ -527,14 +527,15 @@ 
         c->c2.tls_multi->dco_peer_id = -1;
     }
 #endif
-    int ret = dco_new_peer(&c->c1.tuntap->dco, multi->peer_id, sock->sd, NULL,
-                           proto_is_dgram(sock->info.proto) ? remoteaddr : NULL, NULL, NULL);
+    int ret = dco_new_peer(&c->c1.tuntap->dco, multi->rx_peer_id, sock->sd, NULL,
+                           proto_is_dgram(sock->info.proto) ? remoteaddr : NULL,
+                           NULL, NULL);
     if (ret < 0)
     {
         return ret;
     }
 
-    c->c2.tls_multi->dco_peer_id = multi->peer_id;
+    c->c2.tls_multi->dco_peer_id = multi->rx_peer_id;
 
     return 0;
 }
@@ -609,7 +610,7 @@ 
 {
     struct context *c = &mi->context;
 
-    int peer_id = c->c2.tls_multi->peer_id;
+    int peer_id = c->c2.tls_multi->rx_peer_id;
     struct sockaddr *remoteaddr, *localaddr = NULL;
     struct sockaddr_storage local = { 0 };
     const socket_descriptor_t sd = c->c2.link_sockets[0]->sd;
@@ -688,8 +689,7 @@ 
     if (addrtype == MR_ADDR_IPV6)
     {
 #if defined(_WIN32)
-        dco_win_add_iroute_ipv6(&c->c1.tuntap->dco, addr->v6.addr, addr->netbits,
-                                c->c2.tls_multi->peer_id);
+        dco_win_add_iroute_ipv6(&c->c1.tuntap->dco, addr->v6.addr, addr->netbits, c->c2.tls_multi->rx_peer_id);
 #else
         const struct in6_addr *gateway = &mi->context.c2.push_ifconfig_ipv6_local;
         if (addr->type & MR_ONLINK_DCO_ADDR)
@@ -705,8 +705,7 @@ 
     else if (addrtype == MR_ADDR_IPV4)
     {
 #if defined(_WIN32)
-        dco_win_add_iroute_ipv4(&c->c1.tuntap->dco, addr->v4.addr, addr->netbits,
-                                c->c2.tls_multi->peer_id);
+        dco_win_add_iroute_ipv4(&c->c1.tuntap->dco, addr->v4.addr, addr->netbits, c->c2.tls_multi->rx_peer_id);
 #else
         in_addr_t dest = htonl(addr->v4.addr);
         const in_addr_t *gateway = &mi->context.c2.push_ifconfig_local;
diff --git a/src/openvpn/init.c b/src/openvpn/init.c
index cd01520..7c2b073 100644
--- a/src/openvpn/init.c
+++ b/src/openvpn/init.c
@@ -2199,7 +2199,7 @@ 
 
     if (o->use_peer_id)
     {
-        buf_printf(&out, ", peer-id: %d", o->peer_id);
+        buf_printf(&out, ", rx-peer-id: %u, tx-peer-id: %u", c->c2.tls_multi->rx_peer_id, c->c2.tls_multi->tx_peer_id);
     }
 
 #ifdef USE_COMP
@@ -2678,7 +2678,12 @@ 
     {
         msg(D_PUSH_DEBUG, "OPTIONS IMPORT: peer-id set");
         c->c2.tls_multi->use_peer_id = true;
-        c->c2.tls_multi->peer_id = c->options.peer_id;
+        c->c2.tls_multi->tx_peer_id = c->options.peer_id;
+        if (!c->c2.tls_multi->use_asymmetric_peer_id)
+        {
+            c->c2.tls_multi->rx_peer_id = c->options.peer_id;
+            c->c2.tls_multi->tx_peer_id = c->options.peer_id;
+        }
     }
 
     /* process (potentially) pushed options */
@@ -3455,6 +3460,10 @@ 
     if (c->c2.tls_multi)
     {
         tls_multi_init_finalize(c->c2.tls_multi, c->options.ce.tls_mtu);
+        if (c->c2.tls_multi->rx_peer_id != MAX_PEER_ID)
+        {
+            c->options.use_peer_id = true;
+        }
         ASSERT(c->c2.tls_multi->opt.frame.buf.payload_size <= c->c2.frame.buf.payload_size);
         frame_print(&c->c2.tls_multi->opt.frame, D_MTU_INFO, "Control Channel MTU parms");
 
diff --git a/src/openvpn/misc.c b/src/openvpn/misc.c
index 188f44e..061c573 100644
--- a/src/openvpn/misc.c
+++ b/src/openvpn/misc.c
@@ -761,14 +761,15 @@ 
     {
         chomp(line);
         if (validate_peer_info_line(line)
-            && (strncmp(line, "IV_", 3) == 0 || strncmp(line, "UV_", 3) == 0))
+            && (strncmp(line, "IV_", 3) == 0 || strncmp(line, "UV_", 3) == 0
+                || strncmp(line, "ID", 2) == 0))
         {
             msg(M_INFO, "peer info: %s", line);
             env_set_add(es, line);
         }
         else
         {
-            msg(M_WARN, "validation failed on peer_info line received from client");
+            msg(M_WARN, "validation failed on peer_info line received");
         }
     }
 }
diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index 329d0a3..8f2344b 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -438,7 +438,7 @@ 
         if (mi->context.c2.tls_multi && check_debug_level(D_DCO_DEBUG)
             && dco_enabled(&mi->context.options))
         {
-            buf_printf(&out, " peer-id=%d", mi->context.c2.tls_multi->peer_id);
+            buf_printf(&out, " rx-peer-id=%d", mi->context.c2.tls_multi->rx_peer_id);
         }
         return BSTR(&out);
     }
@@ -610,9 +610,9 @@ 
         }
 #endif
 
-        if (mi->context.c2.tls_multi->peer_id != MAX_PEER_ID)
+        if (mi->context.c2.tls_multi->rx_peer_id != MAX_PEER_ID)
         {
-            m->instances[mi->context.c2.tls_multi->peer_id] = NULL;
+            m->instances[mi->context.c2.tls_multi->rx_peer_id] = NULL;
         }
 
         schedule_remove_entry(m->schedule, (struct schedule_entry *)mi);
@@ -925,8 +925,7 @@ 
 #else
                         sep,
 #endif
-                        sep,
-                        mi->context.c2.tls_multi ? mi->context.c2.tls_multi->peer_id : UINT32_MAX,
+                        sep, mi->context.c2.tls_multi ? mi->context.c2.tls_multi->rx_peer_id : UINT32_MAX,
                         sep, translate_cipher_name_to_openvpn(mi->context.options.ciphername));
                 }
                 gc_free(&gc);
@@ -1750,6 +1749,7 @@ 
         tls_multi->use_peer_id = true;
         o->use_peer_id = true;
     }
+
     else if (dco_enabled(o))
     {
         msg(M_INFO, "Client does not support DATA_V2. Data channel offloading "
@@ -3149,12 +3149,12 @@ 
          * has, so we disallow it. This can happen if a DCO netlink notification
          * gets lost and we miss a floating step.
          */
-        if (m1->peer_id == m2->peer_id)
+        if (m1->rx_peer_id == m2->rx_peer_id)
         {
             msg(M_WARN,
                 "disallowing peer %" PRIu32 " (%s) from floating to "
                 "its own address (%s)",
-                m1->peer_id, tls_common_name(mi->context.c2.tls_multi, false),
+                m1->rx_peer_id, tls_common_name(mi->context.c2.tls_multi, false),
                 mroute_addr_print(&mi->real, &gc));
             goto done;
         }
@@ -3167,9 +3167,10 @@ 
     }
 
     msg(D_MULTI_MEDIUM, "peer %" PRIu32 " (%s) floated from %s to %s",
-        mi->context.c2.tls_multi->peer_id, tls_common_name(mi->context.c2.tls_multi, false),
-        mroute_addr_print_ex(&mi->real, MAPF_SHOW_FAMILY, &gc),
-        mroute_addr_print_ex(&real, MAPF_SHOW_FAMILY, &gc));
+        mi->context.c2.tls_multi->rx_peer_id,
+        tls_common_name(mi->context.c2.tls_multi, false),
+        mroute_addr_print(&mi->real, &gc),
+        print_link_socket_actual(&m->top.c2.from, &gc));
 
     /* remove old address from hash table before changing address */
     ASSERT(hash_remove(m->hash, &mi->real));
@@ -4129,7 +4130,7 @@ 
     {
         if (!m->instances[i])
         {
-            mi->context.c2.tls_multi->peer_id = i;
+            mi->context.c2.tls_multi->rx_peer_id = i;
             m->instances[i] = mi;
             break;
         }
@@ -4137,7 +4138,7 @@ 
 
     /* should not really end up here, since multi_create_instance returns null
      * if amount of clients exceeds max_clients */
-    ASSERT(mi->context.c2.tls_multi->peer_id < m->max_clients);
+    ASSERT(mi->context.c2.tls_multi->rx_peer_id < m->max_clients);
 }
 
 /**
diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index 34af0d3..aee7e68 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -3880,6 +3880,7 @@ 
                      "incompatible with each other.");
     }
 
+
     if (dco_enabled(o))
     {
         /* check if any option should force disabling DCO */
diff --git a/src/openvpn/push.c b/src/openvpn/push.c
index 898d158..7e40a6c 100644
--- a/src/openvpn/push.c
+++ b/src/openvpn/push.c
@@ -663,9 +663,10 @@ 
                         print_in_addr_t(c->c2.push_ifconfig_remote_netmask, 0, gc));
     }
 
-    if (tls_multi->use_peer_id)
+    if (!tls_multi->use_asymmetric_peer_id)
     {
-        push_option_fmt(gc, push_list, M_USAGE, "peer-id %d", tls_multi->peer_id);
+        push_option_fmt(gc, push_list, M_USAGE, "peer-id %d",
+                        tls_multi->rx_peer_id);
     }
     /*
      * If server uses --auth-gen-token and we have an auth token
diff --git a/src/openvpn/push_util.c b/src/openvpn/push_util.c
index 51c7b5f..1b811ed 100644
--- a/src/openvpn/push_util.c
+++ b/src/openvpn/push_util.c
@@ -188,7 +188,7 @@ 
         unsigned int permission_mask = pull_permission_mask(c);
         if (process_push_update(c, &o, permission_mask, &option_types_found, &tmp_msg, true) == PUSH_MSG_ERROR)
         {
-            msg(M_WARN, "Failed to process push update message sent to client ID: %u", c->c2.tls_multi->peer_id);
+            msg(M_WARN, "Failed to process push update message sent to client ID: %u", c->c2.tls_multi->rx_peer_id);
         }
         e = e->next;
     }
@@ -294,7 +294,7 @@ 
 
         if (!support_push_update(mi))
         {
-            msg(M_CLIENT, "PUSH_UPDATE: not sending message to unsupported peer with ID: %u", mi->context.c2.tls_multi->peer_id);
+            msg(M_CLIENT, "PUSH_UPDATE: not sending message to unsupported peer with ID: %u", mi->context.c2.tls_multi->rx_peer_id);
             buffer_list_free(msgs);
             gc_free(&gc);
             return 0;
@@ -332,7 +332,7 @@ 
         /* Type is UPT_BROADCAST so we update every client */
         if (!send_single_push_update(m, curr_mi, msgs))
         {
-            msg(M_CLIENT, "ERROR: Peer ID: %u has not been updated", curr_mi->context.c2.tls_multi->peer_id);
+            msg(M_CLIENT, "ERROR: Peer ID: %u has not been updated", curr_mi->context.c2.tls_multi->rx_peer_id);
             continue;
         }
         count++;
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index 741f40a..5f61836 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -1160,7 +1160,10 @@ 
     /* get command line derived options */
     ret->opt = *tls_options;
     ret->dco_peer_id = -1;
-    ret->peer_id = MAX_PEER_ID;
+    ret->use_asymmetric_peer_id = false;
+    /* The rx_peer_id is also used to identify DCO clients */
+    ret->rx_peer_id = MAX_PEER_ID;
+    ret->tx_peer_id = MAX_PEER_ID;
 
     return ret;
 }
@@ -1173,6 +1176,22 @@ 
 
     tls_session_init(multi, &multi->session[TM_ACTIVE]);
     tls_session_init(multi, &multi->session[TM_INITIAL]);
+
+    if (!multi->opt.dco_enabled)
+    {
+        /* Calculate the asymmetric peer-id */
+        if (multi->rx_peer_id == MAX_PEER_ID && multi->session[TM_INITIAL].opt->mode != MODE_SERVER)
+        {
+            uint8_t peerid[3];
+            srand((unsigned)time(NULL));
+            for (int i = 0; i < 3; i++)
+            {
+                peerid[i] = (uint8_t)rand();
+            }
+
+            multi->rx_peer_id = (peerid[0] << 16) + (peerid[1] << 8) + peerid[2];
+        }
+    }
 }
 
 /*
@@ -1850,6 +1869,28 @@ 
     return str;
 }
 
+static bool
+push_peer_info_server(struct buffer *buf, struct tls_session *session, uint32_t peer_id)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+    struct buffer out = alloc_buf_gc(64, &gc);
+
+    if (peer_id != MAX_PEER_ID && (!session->opt->dco_enabled))
+    {
+        buf_printf(&out, "ID=%x\n", peer_id);
+    }
+    if (!write_string(buf, BSTR(&out), -1))
+    {
+        goto error;
+    }
+    ret = true;
+
+error:
+    gc_free(&gc);
+    return ret;
+}
+
 /**
  * Prepares the IV_ and UV_ variables that are part of the
  * exchange to signal the peer's capabilities. The amount
@@ -1863,10 +1904,11 @@ 
  *
  * @param buf       the buffer to write these variables to
  * @param session   the TLS session object
+ * @param peer_id   the asymmetric peer-id used for incoming packets
  * @return          true if no error was encountered
  */
 static bool
-push_peer_info(struct buffer *buf, struct tls_session *session)
+push_peer_info(struct buffer *buf, struct tls_session *session, uint32_t peer_id)
 {
     struct gc_arena gc = gc_new();
     bool ret = false;
@@ -1964,6 +2006,11 @@ 
 
         buf_printf(&out, "IV_PROTO=%d\n", iv_proto);
 
+        if (peer_id != MAX_PEER_ID && (!session->opt->dco_enabled))
+        {
+            buf_printf(&out, "ID=%x\n", peer_id);
+        }
+
         if (session->opt->push_peer_info_detail > 1)
         {
             /* push compression status */
@@ -2144,11 +2191,16 @@ 
         }
     }
 
-    if (!push_peer_info(buf, session))
+    if (!push_peer_info(buf, session, multi->rx_peer_id))
     {
         goto error;
     }
 
+    if (session->opt->mode == MODE_SERVER && multi->use_asymmetric_peer_id && !session->opt->push_peer_info_detail)
+    {
+        push_peer_info_server(buf, session, multi->rx_peer_id);
+    }
+
     if (session->opt->server && session->opt->mode != MODE_SERVER && ks->key_id == 0)
     {
         /* tls-server option set and not P2MP server, so we
@@ -2257,6 +2309,44 @@ 
     if (multi->peer_info)
     {
         output_peer_info_env(session->opt->es, multi->peer_info);
+        if (session->opt->mode == MODE_SERVER)
+        {
+            if (!session->opt->dco_enabled)
+            {
+                uint32_t peer_id = extract_asymmetric_peer_id(multi->peer_info);
+                if (peer_id != UINT32_MAX)
+                {
+                    multi->tx_peer_id = peer_id;
+                    multi->use_asymmetric_peer_id = true;
+                    multi->use_peer_id = true;
+                }
+                else
+                {
+                    /* Client has no asymmetric peer-id capability */
+                    multi->tx_peer_id = multi->rx_peer_id;
+                }
+            }
+            else
+            {
+                /* With DCO we don't need the tx_peer_id atm */
+                multi->tx_peer_id = multi->rx_peer_id;
+            }
+        }
+    }
+    else
+    {
+        free(multi->peer_info);
+        multi->peer_info = read_string_alloc(buf);
+    }
+    if (session->opt->mode == MODE_POINT_TO_POINT && !session->opt->dco_enabled)
+    {
+        uint32_t peer_id = extract_asymmetric_peer_id(multi->peer_info);
+        if (peer_id != UINT32_MAX)
+        {
+            multi->tx_peer_id = peer_id;
+            multi->use_asymmetric_peer_id = true;
+            multi->use_peer_id = true;
+        }
     }
 
     free(multi->remote_ciphername);
@@ -3981,8 +4071,8 @@ 
     msg(D_TLS_DEBUG, __func__);
 
     ASSERT(ks);
-
-    peer = htonl(((P_DATA_V2 << P_OPCODE_SHIFT) | ks->key_id) << 24 | (multi->peer_id & 0xFFFFFF));
+    peer = htonl(((P_DATA_V2 << P_OPCODE_SHIFT) | ks->key_id) << 24
+                 | (multi->tx_peer_id & 0xFFFFFF));
     ASSERT(buf_write_prepend(buf, &peer, 4));
 }
 
diff --git a/src/openvpn/ssl_common.h b/src/openvpn/ssl_common.h
index 3129299..bd8cb23 100644
--- a/src/openvpn/ssl_common.h
+++ b/src/openvpn/ssl_common.h
@@ -698,8 +698,10 @@ 
 #define AUTH_TOKEN_VALID_EMPTYUSER (1 << 2)
 
     /* For P_DATA_V2 */
-    uint32_t peer_id;
+    uint32_t rx_peer_id;
+    uint32_t tx_peer_id;
     bool use_peer_id;
+    bool use_asymmetric_peer_id;
 
     char *remote_ciphername; /**< cipher specified in peer's config file */
     bool remote_usescomp;    /**< remote announced comp-lzo in OCC string */
diff --git a/src/openvpn/ssl_ncp.c b/src/openvpn/ssl_ncp.c
index d4519b0..16066bb 100644
--- a/src/openvpn/ssl_ncp.c
+++ b/src/openvpn/ssl_ncp.c
@@ -406,6 +406,7 @@ 
 {
     /* will return 0 if peer_info is null */
     const unsigned int iv_proto_peer = extract_iv_proto(multi->peer_info);
+    const unsigned int tx_peer_id = extract_asymmetric_peer_id(multi->peer_info);
 
     /* The other peer does not support P2P NCP */
     if (!(iv_proto_peer & IV_PROTO_NCP_P2P))
@@ -416,7 +417,11 @@ 
     if (iv_proto_peer & IV_PROTO_DATA_V2)
     {
         multi->use_peer_id = true;
-        multi->peer_id = 0x76706e; /* 'v' 'p' 'n' */
+        if (tx_peer_id == UINT32_MAX)
+        {
+            multi->rx_peer_id = 0x76706e; /* 'v' 'p' 'n' */
+            multi->tx_peer_id = 0x76706e; /* 'v' 'p' 'n' */
+        }
     }
 
     if (iv_proto_peer & IV_PROTO_CC_EXIT_NOTIFY)
@@ -440,8 +445,16 @@ 
     {
         session->opt->crypto_flags |= CO_USE_TLS_KEY_MATERIAL_EXPORT;
 
-        if (multi->use_peer_id)
+        /* The asymmetric peer-id trumps on the EKM generated ones */
+        if ((tx_peer_id != UINT32_MAX) && (!multi->opt.dco_enabled))
         {
+            multi->tx_peer_id = tx_peer_id;
+            multi->use_asymmetric_peer_id = true;
+        }
+        else
+        {
+            multi->rx_peer_id = 0x76706e; /* 'v' 'p' 'n' */
+            multi->tx_peer_id = 0x76706e; /* 'v' 'p' 'n' */
             /* Using a non hardcoded peer-id makes a tiny bit harder to
              * fingerprint packets and also gives each connection a unique
              * peer-id that can be useful for NAT tracking etc. */
@@ -458,7 +471,8 @@ 
             }
             else
             {
-                multi->peer_id = (peerid[0] << 16) + (peerid[1] << 8) + peerid[2];
+                multi->rx_peer_id = (peerid[0] << 16) + (peerid[1] << 8) + peerid[2];
+                multi->tx_peer_id = multi->rx_peer_id;
             }
         }
     }
@@ -500,11 +514,13 @@ 
         common_cipher = BSTR(&out);
     }
 
-    msg(D_TLS_DEBUG_LOW,
-        "P2P mode NCP negotiation result: "
-        "TLS_export=%d, DATA_v2=%d, peer-id %d, epoch=%d, cipher=%s",
-        (bool)(session->opt->crypto_flags & CO_USE_TLS_KEY_MATERIAL_EXPORT), multi->use_peer_id,
-        multi->peer_id, (bool)(session->opt->crypto_flags & CO_EPOCH_DATA_KEY_FORMAT),
+    msg(D_TLS_DEBUG_LOW, "P2P mode NCP negotiation result: "
+                         "TLS_export=%d, DATA_v2=%d, rx-peer-id %d, tx-peer-id %d, epoch=%d, cipher=%s",
+        (bool)(session->opt->crypto_flags & CO_USE_TLS_KEY_MATERIAL_EXPORT),
+        multi->use_peer_id,
+        multi->rx_peer_id,
+        multi->tx_peer_id,
+        (bool)(session->opt->crypto_flags & CO_EPOCH_DATA_KEY_FORMAT),
         common_cipher);
 
     gc_free(&gc);
diff --git a/src/openvpn/ssl_util.c b/src/openvpn/ssl_util.c
index fb7cf3e..16eb183 100644
--- a/src/openvpn/ssl_util.c
+++ b/src/openvpn/ssl_util.c
@@ -72,6 +72,24 @@ 
     return 0;
 }
 
+uint32_t
+extract_asymmetric_peer_id(const char *peer_info)
+{
+    const char *optstr = peer_info ? strstr(peer_info, "ID=") : NULL;
+    if (optstr)
+    {
+        uint32_t peer_id = 0;
+        int r = sscanf(optstr, "ID=%x", &peer_id);
+        {
+            if (r == 1 && peer_id < UINT32_MAX)
+            {
+                return peer_id;
+            }
+        }
+    }
+    return UINT32_MAX;
+}
+
 const char *
 options_string_compat_lzo(const char *options, struct gc_arena *gc)
 {
diff --git a/src/openvpn/ssl_util.h b/src/openvpn/ssl_util.h
index 007ed69..ec3c85a 100644
--- a/src/openvpn/ssl_util.h
+++ b/src/openvpn/ssl_util.h
@@ -53,6 +53,15 @@ 
  */
 unsigned int extract_iv_proto(const char *peer_info);
 
+
+/**
+ * Extracts the ID variable and returns its value or
+ * UINT32_MAX if it cannot be extracted.
+ *
+ * @param peer_info     peer info string to search for ID
+ */
+uint32_t extract_asymmetric_peer_id(const char *peer_info);
+
 /**
  * Takes a locally produced OCC string for TLS server mode and modifies as
  * if the option comp-lzo was enabled. This is to send a client in