open62541/src/client/ua_client.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "ua_client.h"
#include "ua_client_internal.h"
#include "ua_connection_internal.h"
#include "ua_types_encoding_binary.h"
#include "ua_types_generated_encoding_binary.h"
#include "ua_transport_generated.h"
#include "ua_transport_generated_handling.h"
#include "ua_transport_generated_encoding_binary.h"
#include "ua_util.h"
#include "ua_nodeids.h"

/*********************/
/* Create and Delete */
/*********************/

static void UA_Client_init(UA_Client* client, UA_ClientConfig config) {
    memset(client, 0, sizeof(UA_Client));
    client->channel.connection = &client->connection;
    client->config = config;
}

UA_Client * UA_Client_new(UA_ClientConfig config) {
    UA_Client *client = (UA_Client*)UA_calloc(1, sizeof(UA_Client));
    if(!client)
        return NULL;
    UA_Client_init(client, config);
    return client;
}

static void UA_Client_deleteMembers(UA_Client* client) {
    UA_Client_disconnect(client);
    UA_SecureChannel_deleteMembersCleanup(&client->channel);
    UA_Connection_deleteMembers(&client->connection);
    if(client->endpointUrl.data)
        UA_String_deleteMembers(&client->endpointUrl);
    UA_UserTokenPolicy_deleteMembers(&client->token);
    UA_NodeId_deleteMembers(&client->authenticationToken);
    if(client->username.data)
        UA_String_deleteMembers(&client->username);
    if(client->password.data)
        UA_String_deleteMembers(&client->password);
#ifdef UA_ENABLE_SUBSCRIPTIONS
    UA_Client_NotificationsAckNumber *n, *tmp;
    LIST_FOREACH_SAFE(n, &client->pendingNotificationsAcks, listEntry, tmp) {
        LIST_REMOVE(n, listEntry);
        free(n);
    }
    UA_Client_Subscription *sub, *tmps;
    LIST_FOREACH_SAFE(sub, &client->subscriptions, listEntry, tmps)
        UA_Client_Subscriptions_forceDelete(client, sub); /* force local removal */
#endif
}

void UA_Client_reset(UA_Client* client){
    UA_Client_deleteMembers(client);
    UA_Client_init(client, client->config);
}

void UA_Client_delete(UA_Client* client){
    UA_Client_deleteMembers(client);
    UA_free(client);
}

UA_ClientState UA_EXPORT UA_Client_getState(UA_Client *client) {
    if(!client)
        return UA_CLIENTSTATE_ERRORED;
    return client->state;
}

/*************************/
/* Manage the Connection */
/*************************/

#define UA_MINMESSAGESIZE 8192

static UA_StatusCode HelAckHandshake(UA_Client *client) {
    /* Get a buffer */
    UA_ByteString message;
    UA_Connection *conn = &client->connection;
    UA_StatusCode retval = conn->getSendBuffer(conn, UA_MINMESSAGESIZE, &message);
    if(retval != UA_STATUSCODE_GOOD)
        return retval;

    /* Prepare the HEL message and encode at offset 8 */
    UA_TcpHelloMessage hello;
    UA_String_copy(&client->endpointUrl, &hello.endpointUrl); /* must be less than 4096 bytes */
    hello.maxChunkCount = conn->localConf.maxChunkCount;
    hello.maxMessageSize = conn->localConf.maxMessageSize;
    hello.protocolVersion = conn->localConf.protocolVersion;
    hello.receiveBufferSize = conn->localConf.recvBufferSize;
    hello.sendBufferSize = conn->localConf.sendBufferSize;

    size_t offset = 8;
    retval = UA_TcpHelloMessage_encodeBinary(&hello, &message, &offset);
    UA_TcpHelloMessage_deleteMembers(&hello);

    /* Encode the message header at offset 0 */
    UA_TcpMessageHeader messageHeader;
    messageHeader.messageTypeAndChunkType = UA_CHUNKTYPE_FINAL + UA_MESSAGETYPE_HEL;
    messageHeader.messageSize = (UA_UInt32)offset;
    offset = 0;
    retval |= UA_TcpMessageHeader_encodeBinary(&messageHeader, &message, &offset);
    if(retval != UA_STATUSCODE_GOOD) {
        conn->releaseSendBuffer(conn, &message);
        return retval;
    }

    /* Send the HEL message */
    message.length = messageHeader.messageSize;
    retval = conn->send(conn, &message);
    if(retval != UA_STATUSCODE_GOOD) {
        UA_LOG_INFO(client->config.logger, UA_LOGCATEGORY_NETWORK,
                    "Sending HEL failed");
        return retval;
    }
    UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_NETWORK,
                 "Sent HEL message");

    /* Loop until we have a complete chunk */
    UA_ByteString reply = UA_BYTESTRING_NULL;
    UA_Boolean realloced = false;
    retval = UA_Connection_receiveChunksBlocking(conn, &reply, &realloced,
                                                 client->config.timeout);
    if(retval != UA_STATUSCODE_GOOD) {
        UA_LOG_INFO(client->config.logger, UA_LOGCATEGORY_NETWORK,
                    "Receiving ACK message failed");
        return retval;
    }

    /* Decode the message */
    offset = 0;
    UA_TcpAcknowledgeMessage ackMessage;
    retval = UA_TcpMessageHeader_decodeBinary(&reply, &offset, &messageHeader);
    retval |= UA_TcpAcknowledgeMessage_decodeBinary(&reply, &offset, &ackMessage);

    /* Free the message buffer */
    if(!realloced)
        conn->releaseRecvBuffer(conn, &reply);
    else
        UA_ByteString_deleteMembers(&reply);

    /* Store remote connection settings and adjust local configuration to not
       exceed the limits */
    if(retval == UA_STATUSCODE_GOOD) {
        UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_NETWORK, "Received ACK message");
        conn->remoteConf.maxChunkCount = ackMessage.maxChunkCount; /* may be zero -> unlimited */
        conn->remoteConf.maxMessageSize = ackMessage.maxMessageSize; /* may be zero -> unlimited */
        conn->remoteConf.protocolVersion = ackMessage.protocolVersion;
        conn->remoteConf.sendBufferSize = ackMessage.sendBufferSize;
        conn->remoteConf.recvBufferSize = ackMessage.receiveBufferSize;
        if(conn->remoteConf.recvBufferSize < conn->localConf.sendBufferSize)
            conn->localConf.sendBufferSize = conn->remoteConf.recvBufferSize;
        if(conn->remoteConf.sendBufferSize < conn->localConf.recvBufferSize)
            conn->localConf.recvBufferSize = conn->remoteConf.sendBufferSize;
        conn->state = UA_CONNECTION_ESTABLISHED;
    } else {
        UA_LOG_INFO(client->config.logger, UA_LOGCATEGORY_NETWORK, "Decoding ACK message failed");
    }
    UA_TcpAcknowledgeMessage_deleteMembers(&ackMessage);

    return retval;
}

static UA_StatusCode
SecureChannelHandshake(UA_Client *client, UA_Boolean renew) {
    /* Check if sc is still valid */
    if(renew && client->nextChannelRenewal - UA_DateTime_nowMonotonic() > 0)
        return UA_STATUSCODE_GOOD;

    UA_Connection *conn = &client->connection;
    if(conn->state != UA_CONNECTION_ESTABLISHED)
        return UA_STATUSCODE_BADSERVERNOTCONNECTED;

    UA_SecureConversationMessageHeader messageHeader;
    messageHeader.messageHeader.messageTypeAndChunkType =
        UA_MESSAGETYPE_OPN + UA_CHUNKTYPE_FINAL;
    if(renew)
        messageHeader.secureChannelId = client->channel.securityToken.channelId;
    else
        messageHeader.secureChannelId = 0;

    UA_SequenceHeader seqHeader;
    seqHeader.sequenceNumber = ++client->channel.sendSequenceNumber;
    seqHeader.requestId = ++client->requestId;

    UA_AsymmetricAlgorithmSecurityHeader asymHeader;
    UA_AsymmetricAlgorithmSecurityHeader_init(&asymHeader);
    asymHeader.securityPolicyUri =
        UA_STRING_ALLOC("http://opcfoundation.org/UA/SecurityPolicy#None");

    /* id of opensecurechannelrequest */
    UA_NodeId requestType =
        UA_NODEID_NUMERIC(0, UA_TYPES[UA_TYPES_OPENSECURECHANNELREQUEST].binaryEncodingId);

    UA_OpenSecureChannelRequest opnSecRq;
    UA_OpenSecureChannelRequest_init(&opnSecRq);
    opnSecRq.requestHeader.timestamp = UA_DateTime_now();
    opnSecRq.requestHeader.authenticationToken = client->authenticationToken;
    opnSecRq.requestedLifetime = client->config.secureChannelLifeTime;
    if(renew) {
        opnSecRq.requestType = UA_SECURITYTOKENREQUESTTYPE_RENEW;
        UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                     "Requesting to renew the SecureChannel");
    } else {
        opnSecRq.requestType = UA_SECURITYTOKENREQUESTTYPE_ISSUE;
        UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                     "Requesting to open a SecureChannel");
    }

    UA_ByteString_copy(&client->channel.clientNonce, &opnSecRq.clientNonce);
    opnSecRq.securityMode = UA_MESSAGESECURITYMODE_NONE;

    UA_ByteString message;
    UA_StatusCode retval = conn->getSendBuffer(conn, conn->remoteConf.recvBufferSize, &message);
    if(retval != UA_STATUSCODE_GOOD) {
        UA_AsymmetricAlgorithmSecurityHeader_deleteMembers(&asymHeader);
        UA_OpenSecureChannelRequest_deleteMembers(&opnSecRq);
        return retval;
    }

    size_t offset = 12;
    retval = UA_AsymmetricAlgorithmSecurityHeader_encodeBinary(&asymHeader, &message, &offset);
    retval |= UA_SequenceHeader_encodeBinary(&seqHeader, &message, &offset);
    retval |= UA_NodeId_encodeBinary(&requestType, &message, &offset);
    retval |= UA_OpenSecureChannelRequest_encodeBinary(&opnSecRq, &message, &offset);
    messageHeader.messageHeader.messageSize = (UA_UInt32)offset;
    offset = 0;
    retval |= UA_SecureConversationMessageHeader_encodeBinary(&messageHeader, &message, &offset);

    UA_AsymmetricAlgorithmSecurityHeader_deleteMembers(&asymHeader);
    UA_OpenSecureChannelRequest_deleteMembers(&opnSecRq);
    if(retval != UA_STATUSCODE_GOOD) {
        client->connection.releaseSendBuffer(&client->connection, &message);
        return retval;
    }

    message.length = messageHeader.messageHeader.messageSize;
    retval = conn->send(conn, &message);
    if(retval != UA_STATUSCODE_GOOD)
        return retval;

    UA_ByteString reply = UA_BYTESTRING_NULL;
    UA_Boolean realloced = false;
    retval = UA_Connection_receiveChunksBlocking(conn, &reply, &realloced,
                                                 client->config.timeout);
    if(retval != UA_STATUSCODE_GOOD) {
        UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                     "Receiving OpenSecureChannelResponse failed");
        return retval;
    }

    /* Decode the header */
    offset = 0;
    UA_SecureConversationMessageHeader_decodeBinary(&reply, &offset, &messageHeader);
    UA_AsymmetricAlgorithmSecurityHeader_decodeBinary(&reply, &offset, &asymHeader);
    UA_SequenceHeader_decodeBinary(&reply, &offset, &seqHeader);
    UA_NodeId_decodeBinary(&reply, &offset, &requestType);
    UA_NodeId expectedRequest =
        UA_NODEID_NUMERIC(0, UA_TYPES[UA_TYPES_OPENSECURECHANNELRESPONSE].binaryEncodingId);
    if(!UA_NodeId_equal(&requestType, &expectedRequest)) {
        UA_ByteString_deleteMembers(&reply);
        UA_AsymmetricAlgorithmSecurityHeader_deleteMembers(&asymHeader);
        UA_NodeId_deleteMembers(&requestType);
        UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "Reply answers the wrong request. Expected OpenSecureChannelResponse.");
        return UA_STATUSCODE_BADINTERNALERROR;
    }

    /* Save the sequence number from server */
    client->channel.receiveSequenceNumber = seqHeader.sequenceNumber;

    /* Decode the response */
    UA_OpenSecureChannelResponse response;
    retval = UA_OpenSecureChannelResponse_decodeBinary(&reply, &offset, &response);

    /* Free the message */
    if(!realloced)
        conn->releaseRecvBuffer(conn, &reply);
    else
        UA_ByteString_deleteMembers(&reply);

    /* Results in either the StatusCode of decoding or the service */
    retval |= response.responseHeader.serviceResult;

    if(retval == UA_STATUSCODE_GOOD) {
        /* Response.securityToken.revisedLifetime is UInt32 we need to cast it
         * to DateTime=Int64 we take 75% of lifetime to start renewing as
         *  described in standard */
        client->nextChannelRenewal = UA_DateTime_nowMonotonic() +
            (UA_DateTime)(response.securityToken.revisedLifetime * (UA_Double)UA_MSEC_TO_DATETIME * 0.75);

        /* Replace the old nonce */
        UA_ChannelSecurityToken_deleteMembers(&client->channel.securityToken);
        UA_ChannelSecurityToken_copy(&response.securityToken, &client->channel.securityToken);
        UA_ByteString_deleteMembers(&client->channel.serverNonce);
        UA_ByteString_copy(&response.serverNonce, &client->channel.serverNonce);

        if(renew)
            UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                         "SecureChannel renewed");
        else
            UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                         "SecureChannel opened");
    } else {
        if(renew)
            UA_LOG_INFO(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                        "SecureChannel could not be renewed "
                        "with error code %s", UA_StatusCode_name(retval));
        else
            UA_LOG_INFO(client->config.logger, UA_LOGCATEGORY_SECURECHANNEL,
                        "SecureChannel could not be opened "
                        "with error code %s", UA_StatusCode_name(retval));
    }

    /* Clean up */
    UA_OpenSecureChannelResponse_deleteMembers(&response);
    UA_AsymmetricAlgorithmSecurityHeader_deleteMembers(&asymHeader);
    return retval;
}

static UA_StatusCode ActivateSession(UA_Client *client) {
    UA_ActivateSessionRequest request;
    UA_ActivateSessionRequest_init(&request);

    request.requestHeader.requestHandle = ++client->requestHandle;
    request.requestHeader.timestamp = UA_DateTime_now();
    request.requestHeader.timeoutHint = 600000;

    //manual ExtensionObject encoding of the identityToken
    if(client->authenticationMethod == UA_CLIENTAUTHENTICATION_NONE) {
        UA_AnonymousIdentityToken* identityToken = UA_AnonymousIdentityToken_new();
        UA_AnonymousIdentityToken_init(identityToken);
        UA_String_copy(&client->token.policyId, &identityToken->policyId);
        request.userIdentityToken.encoding = UA_EXTENSIONOBJECT_DECODED;
        request.userIdentityToken.content.decoded.type = &UA_TYPES[UA_TYPES_ANONYMOUSIDENTITYTOKEN];
        request.userIdentityToken.content.decoded.data = identityToken;
    } else {
        UA_UserNameIdentityToken* identityToken = UA_UserNameIdentityToken_new();
        UA_UserNameIdentityToken_init(identityToken);
        UA_String_copy(&client->token.policyId, &identityToken->policyId);
        UA_String_copy(&client->username, &identityToken->userName);
        UA_String_copy(&client->password, &identityToken->password);
        request.userIdentityToken.encoding = UA_EXTENSIONOBJECT_DECODED;
        request.userIdentityToken.content.decoded.type = &UA_TYPES[UA_TYPES_USERNAMEIDENTITYTOKEN];
        request.userIdentityToken.content.decoded.data = identityToken;
    }

    UA_ActivateSessionResponse response;
    __UA_Client_Service(client, &request, &UA_TYPES[UA_TYPES_ACTIVATESESSIONREQUEST],
                        &response, &UA_TYPES[UA_TYPES_ACTIVATESESSIONRESPONSE]);

    if(response.responseHeader.serviceResult) {
        UA_LOG_ERROR(client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "ActivateSession failed with statuscode 0x%08x",
                     response.responseHeader.serviceResult);
    }

    UA_StatusCode retval = response.responseHeader.serviceResult;
    UA_ActivateSessionRequest_deleteMembers(&request);
    UA_ActivateSessionResponse_deleteMembers(&response);
    return retval;
}

/* Gets a list of endpoints. Memory is allocated for endpointDescription array */
static UA_StatusCode
GetEndpoints(UA_Client *client, size_t* endpointDescriptionsSize,
             UA_EndpointDescription** endpointDescriptions) {
    UA_GetEndpointsRequest request;
    UA_GetEndpointsRequest_init(&request);
    request.requestHeader.timestamp = UA_DateTime_now();
    request.requestHeader.timeoutHint = 10000;
    // assume the endpointurl outlives the service call
    request.endpointUrl = client->endpointUrl; 

    UA_GetEndpointsResponse response;
    UA_GetEndpointsResponse_init(&response);
    __UA_Client_Service(client, &request, &UA_TYPES[UA_TYPES_GETENDPOINTSREQUEST],
                        &response, &UA_TYPES[UA_TYPES_GETENDPOINTSRESPONSE]);

    if(response.responseHeader.serviceResult != UA_STATUSCODE_GOOD) {
        UA_StatusCode retval = response.responseHeader.serviceResult;
        UA_LOG_ERROR(client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "GetEndpointRequest failed with statuscode 0x%08x", retval);
        UA_GetEndpointsResponse_deleteMembers(&response);
        return retval;
    }
    *endpointDescriptions = response.endpoints;
    *endpointDescriptionsSize = response.endpointsSize;
    response.endpoints = NULL;
    response.endpointsSize = 0;
    UA_GetEndpointsResponse_deleteMembers(&response);
    return UA_STATUSCODE_GOOD;
}

static UA_StatusCode EndpointsHandshake(UA_Client *client) {
    UA_EndpointDescription* endpointArray = NULL;
    size_t endpointArraySize = 0;
    UA_StatusCode retval = GetEndpoints(client, &endpointArraySize, &endpointArray);
    if(retval != UA_STATUSCODE_GOOD)
        return retval;

    UA_Boolean endpointFound = false;
    UA_Boolean tokenFound = false;
    UA_String securityNone = UA_STRING("http://opcfoundation.org/UA/SecurityPolicy#None");
    UA_String binaryTransport = UA_STRING("http://opcfoundation.org/UA-Profile/"
                                          "Transport/uatcp-uasc-uabinary");

    //TODO: compare endpoint information with client->endpointUri
    for(size_t i = 0; i < endpointArraySize; ++i) {
        UA_EndpointDescription* endpoint = &endpointArray[i];
        /* look out for binary transport endpoints */
        /* Note: Siemens returns empty ProfileUrl, we will accept it as binary */
        if(endpoint->transportProfileUri.length != 0 &&
           !UA_String_equal(&endpoint->transportProfileUri, &binaryTransport))
            continue;
        /* look out for an endpoint without security */
        if(!UA_String_equal(&endpoint->securityPolicyUri, &securityNone))
            continue;
        
        /* endpoint with no security found */
        endpointFound = true;
       
        /* look for a user token policy with an anonymous token */
        for(size_t j = 0; j < endpoint->userIdentityTokensSize; ++j) {
            UA_UserTokenPolicy* userToken = &endpoint->userIdentityTokens[j];

            /* Usertokens also have a security policy... */
            if(userToken->securityPolicyUri.length > 0 &&
               !UA_String_equal(&userToken->securityPolicyUri, &securityNone))
                continue;

            /* UA_CLIENTAUTHENTICATION_NONE == UA_USERTOKENTYPE_ANONYMOUS
             * UA_CLIENTAUTHENTICATION_USERNAME == UA_USERTOKENTYPE_USERNAME
             * TODO: Check equivalence for other types when adding the support */
            if((int)client->authenticationMethod != (int)userToken->tokenType)
                continue;

            /* Endpoint with matching usertokenpolicy found */
            tokenFound = true;
            UA_UserTokenPolicy_copy(userToken, &client->token);
            break;
        }
    }

    UA_Array_delete(endpointArray, endpointArraySize,
                    &UA_TYPES[UA_TYPES_ENDPOINTDESCRIPTION]);

    if(!endpointFound) {
        UA_LOG_ERROR(client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "No suitable endpoint found");
        retval = UA_STATUSCODE_BADINTERNALERROR;
    } else if(!tokenFound) {
        UA_LOG_ERROR(client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "No suitable UserTokenPolicy found for the possible endpoints");
        retval = UA_STATUSCODE_BADINTERNALERROR;
    }
    return retval;
}

static UA_StatusCode SessionHandshake(UA_Client *client) {
    UA_CreateSessionRequest request;
    UA_CreateSessionRequest_init(&request);

    request.requestHeader.timestamp = UA_DateTime_now();
    request.requestHeader.timeoutHint = 10000;
    UA_ByteString_copy(&client->channel.clientNonce, &request.clientNonce);
    request.requestedSessionTimeout = 1200000;
    request.maxResponseMessageSize = UA_INT32_MAX;
    UA_String_copy(&client->endpointUrl, &request.endpointUrl);

    UA_CreateSessionResponse response;
    UA_CreateSessionResponse_init(&response);
    __UA_Client_Service(client, &request, &UA_TYPES[UA_TYPES_CREATESESSIONREQUEST],
                        &response, &UA_TYPES[UA_TYPES_CREATESESSIONRESPONSE]);

    UA_NodeId_copy(&response.authenticationToken, &client->authenticationToken);

    UA_StatusCode retval = response.responseHeader.serviceResult;
    UA_CreateSessionRequest_deleteMembers(&request);
    UA_CreateSessionResponse_deleteMembers(&response);
    return retval;
}

static UA_StatusCode CloseSession(UA_Client *client) {
    UA_CloseSessionRequest request;
    UA_CloseSessionRequest_init(&request);

    request.requestHeader.timestamp = UA_DateTime_now();
    request.requestHeader.timeoutHint = 10000;
    request.deleteSubscriptions = true;
    UA_CloseSessionResponse response;
    __UA_Client_Service(client, &request, &UA_TYPES[UA_TYPES_CLOSESESSIONREQUEST],
                        &response, &UA_TYPES[UA_TYPES_CLOSESESSIONRESPONSE]);

    UA_StatusCode retval = response.responseHeader.serviceResult;
    UA_CloseSessionRequest_deleteMembers(&request);
    UA_CloseSessionResponse_deleteMembers(&response);
    return retval;
}

static UA_StatusCode CloseSecureChannel(UA_Client *client) {
    UA_SecureChannel *channel = &client->channel;
    UA_CloseSecureChannelRequest request;
    UA_CloseSecureChannelRequest_init(&request);
    request.requestHeader.requestHandle = ++client->requestHandle;
    request.requestHeader.timestamp = UA_DateTime_now();
    request.requestHeader.timeoutHint = 10000;
    UA_NodeId_copy(&client->authenticationToken,
                   &request.requestHeader.authenticationToken);

    UA_SecureConversationMessageHeader msgHeader;
    msgHeader.messageHeader.messageTypeAndChunkType = UA_MESSAGETYPE_CLO + UA_CHUNKTYPE_FINAL;
    msgHeader.secureChannelId = channel->securityToken.channelId;

    UA_SymmetricAlgorithmSecurityHeader symHeader;
    symHeader.tokenId = channel->securityToken.tokenId;

    UA_SequenceHeader seqHeader;
    seqHeader.sequenceNumber = ++channel->sendSequenceNumber;
    seqHeader.requestId = ++client->requestId;

    UA_NodeId typeId =
        UA_NODEID_NUMERIC(0, UA_TYPES[UA_TYPES_CLOSESECURECHANNELREQUEST].binaryEncodingId);

    UA_ByteString message;
    UA_Connection *conn = &client->connection;
    UA_StatusCode retval = conn->getSendBuffer(conn, conn->remoteConf.recvBufferSize, &message);
    if(retval != UA_STATUSCODE_GOOD){
        UA_CloseSecureChannelRequest_deleteMembers(&request);
        return retval;
    }

    size_t offset = 12;
    retval |= UA_SymmetricAlgorithmSecurityHeader_encodeBinary(&symHeader, &message, &offset);
    retval |= UA_SequenceHeader_encodeBinary(&seqHeader, &message, &offset);
    retval |= UA_NodeId_encodeBinary(&typeId, &message, &offset);
    retval |= UA_encodeBinary(&request, &UA_TYPES[UA_TYPES_CLOSESECURECHANNELREQUEST],
                              NULL, NULL, &message, &offset);

    msgHeader.messageHeader.messageSize = (UA_UInt32)offset;
    offset = 0;
    retval |= UA_SecureConversationMessageHeader_encodeBinary(&msgHeader, &message, &offset);

    if(retval == UA_STATUSCODE_GOOD) {
        message.length = msgHeader.messageHeader.messageSize;
        retval = conn->send(conn, &message);
    } else {
        conn->releaseSendBuffer(conn, &message);
    }
    conn->close(conn);
    UA_CloseSecureChannelRequest_deleteMembers(&request);
    return retval;
}

UA_StatusCode
UA_Client_connect_username(UA_Client *client, const char *endpointUrl,
                           const char *username, const char *password){
    client->authenticationMethod=UA_CLIENTAUTHENTICATION_USERNAME;
    client->username = UA_STRING_ALLOC(username);
    client->password = UA_STRING_ALLOC(password);
    return UA_Client_connect(client, endpointUrl);
}

static UA_StatusCode
_UA_Client_connect(UA_Client *client, const char *endpointUrl, UA_Boolean endpointsHandshake, UA_Boolean createSession) {
    if(client->state == UA_CLIENTSTATE_CONNECTED)
        return UA_STATUSCODE_GOOD;
    if(client->state == UA_CLIENTSTATE_ERRORED) {
        UA_Client_reset(client);
    }

    UA_StatusCode retval = UA_STATUSCODE_GOOD;
    client->connection =
        client->config.connectionFunc(UA_ConnectionConfig_standard,
                                      endpointUrl, client->config.logger);
    if(client->connection.state != UA_CONNECTION_OPENING) {
        retval = UA_STATUSCODE_BADCONNECTIONCLOSED;
        goto cleanup;
    }

    client->endpointUrl = UA_STRING_ALLOC(endpointUrl);
    if(!client->endpointUrl.data) {
        retval = UA_STATUSCODE_BADOUTOFMEMORY;
        goto cleanup;
    }

    client->connection.localConf = client->config.localConnectionConfig;
    retval = HelAckHandshake(client);
    if(retval == UA_STATUSCODE_GOOD)
        retval = SecureChannelHandshake(client, false);
    if(endpointsHandshake && retval == UA_STATUSCODE_GOOD)
        retval = EndpointsHandshake(client);
    if(endpointsHandshake && createSession && retval == UA_STATUSCODE_GOOD)
        retval = SessionHandshake(client);
    if(endpointsHandshake && createSession && retval == UA_STATUSCODE_GOOD)
        retval = ActivateSession(client);
    if(retval == UA_STATUSCODE_GOOD) {
        client->connection.state = UA_CONNECTION_ESTABLISHED;
        client->state = UA_CLIENTSTATE_CONNECTED;
    } else {
        goto cleanup;
    }
    return retval;

 cleanup:
    UA_Client_reset(client);
    return retval;
}

UA_StatusCode
UA_Client_connect(UA_Client *client, const char *endpointUrl) {
    return _UA_Client_connect(client, endpointUrl, UA_TRUE, UA_TRUE);
}

UA_StatusCode UA_Client_disconnect(UA_Client *client) {
    if(client->state == UA_CLIENTSTATE_READY)
        return UA_STATUSCODE_BADNOTCONNECTED;
    UA_StatusCode retval = UA_STATUSCODE_GOOD;
    /* Is a session established? */
    if(client->connection.state == UA_CONNECTION_ESTABLISHED &&
       !UA_NodeId_equal(&client->authenticationToken, &UA_NODEID_NULL))
        retval = CloseSession(client);
    /* Is a secure channel established? */
    if(client->connection.state == UA_CONNECTION_ESTABLISHED)
        retval |= CloseSecureChannel(client);
    return retval;
}

UA_StatusCode UA_Client_manuallyRenewSecureChannel(UA_Client *client) {
    UA_StatusCode retval = SecureChannelHandshake(client, true);
    if(retval == UA_STATUSCODE_GOOD)
        client->state = UA_CLIENTSTATE_CONNECTED;
    return retval;
}

UA_StatusCode
UA_Client_getEndpoints(UA_Client *client, const char *serverUrl,
                       size_t* endpointDescriptionsSize,
                       UA_EndpointDescription** endpointDescriptions) {
    if (client->state == UA_CLIENTSTATE_CONNECTED &&
        strncmp((const char*)client->endpointUrl.data, serverUrl, client->endpointUrl.length) != 0) {
        // client is already connected but to a different endpoint url.
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    }

    UA_StatusCode retval = _UA_Client_connect(client, serverUrl, UA_FALSE, UA_FALSE);
    if(retval == UA_STATUSCODE_GOOD)
        retval = GetEndpoints(client, endpointDescriptionsSize, endpointDescriptions);

    UA_Client_disconnect(client);
    UA_Client_reset(client);
    return retval;
}

UA_StatusCode
UA_Client_findServers(UA_Client *client, const char *serverUrl,
                      size_t serverUrisSize, UA_String *serverUris,
                      size_t localeIdsSize, UA_String *localeIds,
                      size_t *registeredServerSize, UA_ApplicationDescription **registeredServers) {

    if (client->state == UA_CLIENTSTATE_CONNECTED &&
       strncmp((const char*)client->endpointUrl.data, serverUrl, client->endpointUrl.length) != 0) {
        // client is already connected but to a different endpoint url.
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    }

    UA_StatusCode retval = _UA_Client_connect(client, serverUrl, UA_TRUE, UA_FALSE);
    if (retval != UA_STATUSCODE_GOOD) {
        UA_Client_disconnect(client);
        UA_Client_reset(client);
        return retval;
    }

    UA_FindServersRequest request;
    UA_FindServersRequest_init(&request);

    request.serverUrisSize = serverUrisSize;
    request.serverUris = serverUris;

    request.localeIdsSize = localeIdsSize;
    request.localeIds = localeIds;

    // now send the request
    UA_FindServersResponse response;
    UA_FindServersResponse_init(&response);
    __UA_Client_Service(client, &request, &UA_TYPES[UA_TYPES_FINDSERVERSREQUEST],
                        &response, &UA_TYPES[UA_TYPES_FINDSERVERSRESPONSE]);
    retval = response.responseHeader.serviceResult;
    if (retval != UA_STATUSCODE_GOOD) {
        *registeredServerSize = 0;
        goto cleanup;
    }

    *registeredServerSize = response.serversSize;
    *registeredServers = (UA_ApplicationDescription *) UA_Array_new(response.serversSize,
                                                                    &UA_TYPES[UA_TYPES_APPLICATIONDESCRIPTION]);
    for (size_t i = 0; i < response.serversSize; i++)
        UA_ApplicationDescription_copy(&response.servers[i], &(*registeredServers)[i]);

    /* always cleanup */
    cleanup:
    UA_FindServersResponse_deleteMembers(&response);
    UA_Client_disconnect(client);
    UA_Client_reset(client);
    return retval;
}

UA_StatusCode
UA_Client_findServersOnNetwork(UA_Client *client, const char *serverUrl,
                               UA_UInt32 startingRecordId, UA_UInt32 maxRecordsToReturn,
                               size_t serverCapabilityFilterSize, UA_String *serverCapabilityFilter,
                               size_t *serverOnNetworkSize, UA_ServerOnNetwork **serverOnNetwork) {

    if (client->state == UA_CLIENTSTATE_CONNECTED &&
        strncmp((const char*)client->endpointUrl.data, serverUrl, client->endpointUrl.length) != 0) {
        // client is already connected but to a different endpoint url.
        return UA_STATUSCODE_BADINVALIDARGUMENT;
    }

    UA_StatusCode retval = _UA_Client_connect(client, serverUrl, UA_TRUE, UA_FALSE);
    if (retval != UA_STATUSCODE_GOOD) {
        UA_Client_disconnect(client);
        UA_Client_reset(client);
        return retval;
    }

    UA_FindServersOnNetworkRequest request;
    UA_FindServersOnNetworkRequest_init(&request);

    request.startingRecordId = startingRecordId;
    request.maxRecordsToReturn = maxRecordsToReturn;

    request.serverCapabilityFilterSize = serverCapabilityFilterSize;
    request.serverCapabilityFilter = serverCapabilityFilter;

    // now send the request
    UA_FindServersOnNetworkResponse response;
    UA_FindServersOnNetworkResponse_init(&response);
    __UA_Client_Service(client, &request, &UA_TYPES[UA_TYPES_FINDSERVERSONNETWORKREQUEST],
                        &response, &UA_TYPES[UA_TYPES_FINDSERVERSONNETWORKRESPONSE]);
    retval = response.responseHeader.serviceResult;
    if (retval != UA_STATUSCODE_GOOD) {
        *serverOnNetworkSize = 0;
        goto cleanup;
    }

    *serverOnNetworkSize = response.serversSize;
    *serverOnNetwork = (UA_ServerOnNetwork *) UA_Array_new(response.serversSize, &UA_TYPES[UA_TYPES_SERVERONNETWORK]);
    for (size_t i = 0; i < response.serversSize; i++)
        UA_ServerOnNetwork_copy(&response.servers[i], &(*serverOnNetwork)[i]);

    cleanup:
    UA_FindServersOnNetworkResponse_deleteMembers(&response);
    UA_Client_disconnect(client);
    UA_Client_reset(client);
    return retval;
}

/****************/
/* Raw Services */
/****************/

struct ResponseDescription {
    UA_Client *client;
    UA_Boolean processed;
    UA_UInt32 requestId;
    void *response;
    const UA_DataType *responseType;
};

static void
processServiceResponse(struct ResponseDescription *rd, UA_SecureChannel *channel,
                       UA_MessageType messageType, UA_UInt32 requestId,
                       UA_ByteString *message) {
    UA_StatusCode retval = UA_STATUSCODE_GOOD;
    const UA_NodeId expectedNodeId =
        UA_NODEID_NUMERIC(0, rd->responseType->binaryEncodingId);
    const UA_NodeId serviceFaultNodeId =
        UA_NODEID_NUMERIC(0, UA_TYPES[UA_TYPES_SERVICEFAULT].binaryEncodingId);

    UA_ResponseHeader *respHeader = (UA_ResponseHeader*)rd->response;
    rd->processed = true;

    /* Forward declaration for the goto */
    size_t offset = 0;
    UA_NodeId responseId;

    if(messageType == UA_MESSAGETYPE_ERR) {
        UA_TcpErrorMessage *msg = (UA_TcpErrorMessage*)message;
        UA_LOG_ERROR(rd->client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "Server replied with an error message: %s %.*s",
                     UA_StatusCode_name(msg->error), msg->reason.length, msg->reason.data);
        retval = msg->error;
        goto finish;
    } else if(messageType != UA_MESSAGETYPE_MSG) {
        UA_LOG_ERROR(rd->client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "Server replied with the wrong message type");
        retval = UA_STATUSCODE_BADTCPMESSAGETYPEINVALID;
        goto finish;
    }

    /* Check that the request id matches */
    /* Todo: we need to demux async responses since a publish responses may come
       at any time */
    if(requestId != rd->requestId) {
        UA_LOG_ERROR(rd->client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "Reply answers the wrong requestId. "
                     "Async services are not yet implemented.");
        retval = UA_STATUSCODE_BADINTERNALERROR;
        goto finish;
    }

    /* Check that the response type matches */
    retval = UA_NodeId_decodeBinary(message, &offset, &responseId);
    if(retval != UA_STATUSCODE_GOOD)
        goto finish;
    if(!UA_NodeId_equal(&responseId, &expectedNodeId)) {
        if(UA_NodeId_equal(&responseId, &serviceFaultNodeId)) {
            /* Take the statuscode from the servicefault */
            retval = UA_decodeBinary(message, &offset, rd->response,
                                     &UA_TYPES[UA_TYPES_SERVICEFAULT], 0, NULL);
        } else {
            UA_LOG_ERROR(rd->client->config.logger, UA_LOGCATEGORY_CLIENT,
                         "Reply answers the wrong request. Expected ns=%i,i=%i."
                         "But retrieved ns=%i,i=%i", expectedNodeId.namespaceIndex,
                         expectedNodeId.identifier.numeric, responseId.namespaceIndex,
                         responseId.identifier.numeric);
            UA_NodeId_deleteMembers(&responseId);
            retval = UA_STATUSCODE_BADINTERNALERROR;
        }
        goto finish;
    }

    /* Decode the response */
    retval = UA_decodeBinary(message, &offset, rd->response, rd->responseType,
                             rd->client->config.customDataTypesSize,
                             rd->client->config.customDataTypes);

 finish:
    if(retval == UA_STATUSCODE_GOOD) {
        UA_LOG_DEBUG(rd->client->config.logger, UA_LOGCATEGORY_CLIENT,
                     "Received a response of type %i", responseId.identifier.numeric);
    } else {
        if(retval == UA_STATUSCODE_BADENCODINGLIMITSEXCEEDED)
            retval = UA_STATUSCODE_BADRESPONSETOOLARGE;
        UA_LOG_INFO(rd->client->config.logger, UA_LOGCATEGORY_CLIENT,
                    "Error receiving the response");
        respHeader->serviceResult = retval;
    }
}

void
__UA_Client_Service(UA_Client *client, const void *request, const UA_DataType *requestType,
                    void *response, const UA_DataType *responseType) {
    UA_init(response, responseType);
    UA_ResponseHeader *respHeader = (UA_ResponseHeader*)response;

    /* Make sure we have a valid session */
    UA_StatusCode retval = UA_Client_manuallyRenewSecureChannel(client);
    if(retval != UA_STATUSCODE_GOOD) {
        respHeader->serviceResult = retval;
        client->state = UA_CLIENTSTATE_ERRORED;
        return;
    }

    /* Adjusting the request header. The const attribute is violated, but we
     * only touch the following members: */
    UA_RequestHeader *rr = (UA_RequestHeader*)(uintptr_t)request;
    rr->authenticationToken = client->authenticationToken; /* cleaned up at the end */
    rr->timestamp = UA_DateTime_now();
    rr->requestHandle = ++client->requestHandle;

    /* Send the request */
    UA_UInt32 requestId = ++client->requestId;
    UA_LOG_DEBUG(client->config.logger, UA_LOGCATEGORY_CLIENT,
                 "Sending a request of type %i", requestType->typeId.identifier.numeric);
    retval = UA_SecureChannel_sendBinaryMessage(&client->channel, requestId, rr, requestType);
    if(retval != UA_STATUSCODE_GOOD) {
        if(retval == UA_STATUSCODE_BADENCODINGLIMITSEXCEEDED)
            respHeader->serviceResult = UA_STATUSCODE_BADREQUESTTOOLARGE;
        else
            respHeader->serviceResult = retval;
        client->state = UA_CLIENTSTATE_FAULTED;
        UA_NodeId_init(&rr->authenticationToken);
        return;
    }

    /* Prepare the response and the structure we give into processServiceResponse */
    UA_init(response, responseType);
    struct ResponseDescription rd = {client, false, requestId, response, responseType};

    /* Retrieve the response */
    UA_DateTime maxDate = UA_DateTime_nowMonotonic() + (client->config.timeout * UA_MSEC_TO_DATETIME);
    do {
        /* Retrieve complete chunks */
        UA_ByteString reply = UA_BYTESTRING_NULL;
        UA_Boolean realloced = false;
        UA_DateTime now = UA_DateTime_nowMonotonic();
        if(now < maxDate) {
            UA_UInt32 timeout = (UA_UInt32)((maxDate - now) / UA_MSEC_TO_DATETIME);
            retval = UA_Connection_receiveChunksBlocking(&client->connection, &reply, &realloced, timeout);
        } else {
            retval = UA_STATUSCODE_GOODNONCRITICALTIMEOUT;
        }
        if(retval != UA_STATUSCODE_GOOD) {
            respHeader->serviceResult = retval;
            break;
        }
        /* ProcessChunks and call processServiceResponse for complete messages */
        UA_SecureChannel_processChunks(&client->channel, &reply,
                                       (UA_ProcessMessageCallback*)processServiceResponse, &rd);
        /* Free the received buffer */
        if(!realloced)
            client->connection.releaseRecvBuffer(&client->connection, &reply);
        else
            UA_ByteString_deleteMembers(&reply);
    } while(!rd.processed);

    /* Clean up the authentication token */
    UA_NodeId_init(&rr->authenticationToken);
}