src/server_config.c

/**
 * @file server_config.c
 * @author Roman Janota <janota@cesnet.cz>
 * @brief libnetconf2 server configuration functions
 *
 * @copyright
 * Copyright (c) 2022-2023 CESNET, z.s.p.o.
 *
 * This source code is licensed under BSD 3-Clause License (the "License").
 * You may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://opensource.org/licenses/BSD-3-Clause
 */

#define _GNU_SOURCE

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include "compat.h"
#include "libnetconf.h"
#include "server_config.h"
#include "server_config_p.h"
#include "session_server.h"
#include "session_server_ch.h"

/* All libssh supported host-key, key-exchange, encryption and mac algorithms as of version 0.10.90 */

static const char *supported_hostkey_algs[] = {
    "ssh-ed25519-cert-v01@openssh.com", "ecdsa-sha2-nistp521-cert-v01@openssh.com",
    "ecdsa-sha2-nistp384-cert-v01@openssh.com", "ecdsa-sha2-nistp256-cert-v01@openssh.com",
    "rsa-sha2-512-cert-v01@openssh.com", "rsa-sha2-256-cert-v01@openssh.com",
    "ssh-rsa-cert-v01@openssh.com", "ssh-dss-cert-v01@openssh.com",
    "ssh-ed25519", "ecdsa-sha2-nistp521", "ecdsa-sha2-nistp384", "ecdsa-sha2-nistp256",
    "rsa-sha2-512", "rsa-sha2-256", "ssh-rsa", "ssh-dss", NULL
};

static const char *supported_kex_algs[] = {
    "diffie-hellman-group-exchange-sha1", "curve25519-sha256", "curve25519-sha256@libssh.org",
    "ecdh-sha2-nistp256", "ecdh-sha2-nistp384", "ecdh-sha2-nistp521", "diffie-hellman-group18-sha512",
    "diffie-hellman-group16-sha512", "diffie-hellman-group-exchange-sha256", "diffie-hellman-group14-sha256", NULL
};

static const char *supported_encryption_algs[] = {
    "chacha20-poly1305@openssh.com", "aes256-gcm@openssh.com", "aes128-gcm@openssh.com",
    "aes256-ctr", "aes192-ctr", "aes128-ctr", "aes256-cbc", "aes192-cbc", "aes128-cbc",
    "blowfish-cbc", "triple-des-cbc", "none", NULL
};

static const char *supported_mac_algs[] = {
    "hmac-sha2-256-etm@openssh.com", "hmac-sha2-512-etm@openssh.com", "hmac-sha1-etm@openssh.com",
    "hmac-sha2-256", "hmac-sha2-512", "hmac-sha1", NULL
};

extern struct nc_server_opts server_opts;

int
nc_server_config_get_endpt(const struct lyd_node *node, struct nc_endpt **endpt, struct nc_bind **bind)
{
    uint16_t i;
    const char *endpt_name;

    assert(node);

    while (node) {
        if (!strcmp(LYD_NAME(node), "endpoint")) {
            break;
        }
        node = lyd_parent(node);
    }

    if (!node) {
        ERR(NULL, "Node \"%s\" is not contained in an endpoint subtree.", LYD_NAME(node));
        return 1;
    }

    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));
    endpt_name = lyd_get_value(node);

    for (i = 0; i < server_opts.endpt_count; i++) {
        if (!strcmp(server_opts.endpts[i].name, endpt_name)) {
            *endpt = &server_opts.endpts[i];
            if (bind) {
                *bind = &server_opts.binds[i];
            }
            return 0;
        }
    }

    ERR(NULL, "Endpoint \"%s\" was not found.", endpt_name);
    return 1;
}

int
nc_server_config_get_hostkey(const struct lyd_node *node, const struct nc_server_ssh_opts *opts, struct nc_hostkey **hostkey)
{
    uint16_t i;
    const char *hostkey_name;

    assert(node && opts);

    while (node) {
        if (!strcmp(LYD_NAME(node), "host-key")) {
            break;
        }
        node = lyd_parent(node);
    }

    if (!node) {
        ERR(NULL, "Node \"%s\" is not contained in a host-key subtree.", LYD_NAME(node));
        return 1;
    }

    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));
    hostkey_name = lyd_get_value(node);

    for (i = 0; i < opts->hostkey_count; i++) {
        if (!strcmp(opts->hostkeys[i].name, hostkey_name)) {
            *hostkey = &opts->hostkeys[i];
            return 0;
        }
    }

    ERR(NULL, "Host-key \"%s\" was not found.", hostkey_name);
    return 1;
}

int
nc_server_config_get_auth_client(const struct lyd_node *node, const struct nc_server_ssh_opts *opts, struct nc_client_auth **auth_client)
{
    uint16_t i;
    const char *authkey_name;

    assert(node && opts);

    while (node) {
        if (!strcmp(LYD_NAME(node), "user")) {
            break;
        }
        node = lyd_parent(node);
    }

    if (!node) {
        ERR(NULL, "Node \"%s\" is not contained in a client-authentication subtree.", LYD_NAME(node));
        return 1;
    }

    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));
    authkey_name = lyd_get_value(node);

    for (i = 0; i < opts->client_count; i++) {
        if (!strcmp(opts->auth_clients[i].username, authkey_name)) {
            *auth_client = &opts->auth_clients[i];
            return 0;
        }
    }

    ERR(NULL, "Authorized key \"%s\" was not found.", authkey_name);
    return 1;
}

int
nc_server_config_get_pubkey(const struct lyd_node *node, const struct nc_client_auth *auth_client, struct nc_public_key **pubkey)
{
    uint16_t i;
    const char *pubkey_name;

    assert(node && auth_client);

    node = lyd_parent(node);
    while (node) {
        if (!strcmp(LYD_NAME(node), "public-key")) {
            break;
        }
        node = lyd_parent(node);
    }

    if (!node) {
        ERR(NULL, "Node \"%s\" is not contained in a public-key subtree.", LYD_NAME(node));
        return 1;
    }

    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));
    pubkey_name = lyd_get_value(node);

    for (i = 0; i < auth_client->pubkey_count; i++) {
        if (!strcmp(auth_client->pubkeys[i].name, pubkey_name)) {
            *pubkey = &auth_client->pubkeys[i];
            return 0;
        }
    }

    ERR(NULL, "Public key \"%s\" was not found.", pubkey_name);
    return 1;
}

int
equal_parent_name(const struct lyd_node *node, uint16_t parent_count, const char *parent_name)
{
    uint16_t i;

    assert(node && parent_count > 0 && parent_name);

    node = lyd_parent(node);
    for (i = 1; i < parent_count; i++) {
        node = lyd_parent(node);
    }

    if (!strcmp(LYD_NAME(node), parent_name)) {
        return 1;
    }

    return 0;
}

int
nc_server_config_realloc(const char *key_value, void **ptr, size_t size, uint16_t *count)
{
    int ret = 0;
    void *tmp;
    char **name;

    tmp = realloc(*ptr, (*count + 1) * size);
    if (!tmp) {
        ERRMEM;
        ret = 1;
        goto cleanup;
    }
    *ptr = tmp;

    /* set the newly allocated memory to 0 */
    memset((char *)(*ptr) + (*count * size), 0, size);
    (*count)++;

    /* access the first member of the supposed structure */
    name = (char **)((*ptr) + ((*count - 1) * size));

    /* and set it's value */
    *name = strdup(key_value);
    if (!*name) {
        ERRMEM;
        ret = 1;
        goto cleanup;
    }

cleanup:
    return ret;
}

static void
nc_server_config_del_auth_client_pam_name(struct nc_client_auth *auth_client)
{
    free(auth_client->pam_config_name);
    auth_client->pam_config_name = NULL;
}

static void
nc_server_config_del_auth_client_pam_dir(struct nc_client_auth *auth_client)
{
    free(auth_client->pam_config_dir);
    auth_client->pam_config_dir = NULL;
}

static void
nc_server_config_del_endpt_name(struct nc_endpt *endpt)
{
    free(endpt->name);
    endpt->name = NULL;
}

static void
nc_server_config_del_local_address(struct nc_bind *bind)
{
    free(bind->address);
    bind->address = NULL;
}

static void
nc_server_config_del_hostkey_name(struct nc_hostkey *hostkey)
{
    free(hostkey->name);
    hostkey->name = NULL;
}

static void
nc_server_config_del_public_key(struct nc_hostkey *hostkey)
{
    free(hostkey->key.pub_base64);
    hostkey->key.pub_base64 = NULL;
}

static void
nc_server_config_del_private_key(struct nc_hostkey *hostkey)
{
    free(hostkey->key.priv_base64);
    hostkey->key.priv_base64 = NULL;
}

static void
nc_server_config_del_auth_client_username(struct nc_client_auth *auth_client)
{
    free(auth_client->username);
    auth_client->username = NULL;
}

static void
nc_server_config_del_auth_client_pubkey_name(struct nc_public_key *pubkey)
{
    free(pubkey->name);
    pubkey->name = NULL;
}

static void
nc_server_config_del_auth_client_pubkey_pub_base64(struct nc_public_key *pubkey)
{
    free(pubkey->pub_base64);
    pubkey->pub_base64 = NULL;
}

static void
nc_server_config_del_auth_client_password(struct nc_client_auth *auth_client)
{
    free(auth_client->password);
    auth_client->password = NULL;
}

static void
nc_server_config_del_hostkey_algs(struct nc_server_ssh_opts *opts)
{
    free(opts->hostkey_algs);
    opts->hostkey_algs = NULL;
}

static void
nc_server_config_del_kex_algs(struct nc_server_ssh_opts *opts)
{
    free(opts->kex_algs);
    opts->kex_algs = NULL;
}

static void
nc_server_config_del_encryption_algs(struct nc_server_ssh_opts *opts)
{
    free(opts->encryption_algs);
    opts->encryption_algs = NULL;
}

static void
nc_server_config_del_mac_algs(struct nc_server_ssh_opts *opts)
{
    free(opts->mac_algs);
    opts->mac_algs = NULL;
}

static void
nc_server_config_del_hostkey(struct nc_server_ssh_opts *opts, struct nc_hostkey *hostkey)
{
    assert(hostkey->store == NC_STORE_LOCAL || hostkey->store == NC_STORE_KEYSTORE);

    if (hostkey->store == NC_STORE_LOCAL) {
        nc_server_config_del_public_key(hostkey);
        nc_server_config_del_private_key(hostkey);
    }

    nc_server_config_del_hostkey_name(hostkey);
    opts->hostkey_count--;
    if (!opts->hostkey_count) {
        free(opts->hostkeys);
        opts->hostkeys = NULL;
    }
}

static void
nc_server_config_del_auth_client_pubkey(struct nc_client_auth *auth_client, struct nc_public_key *pubkey)
{
    nc_server_config_del_auth_client_pubkey_name(pubkey);
    nc_server_config_del_auth_client_pubkey_pub_base64(pubkey);

    auth_client->pubkey_count--;
    if (!auth_client->pubkey_count) {
        free(auth_client->pubkeys);
        auth_client->pubkeys = NULL;
    }
}

static void
nc_server_config_del_auth_client(struct nc_server_ssh_opts *opts, struct nc_client_auth *auth_client)
{
    uint16_t i, pubkey_count;

    if (auth_client->store == NC_STORE_LOCAL) {
        pubkey_count = auth_client->pubkey_count;
        for (i = 0; i < pubkey_count; i++) {
            nc_server_config_del_auth_client_pubkey(auth_client, &auth_client->pubkeys[i]);
        }
    }

    nc_server_config_del_auth_client_password(auth_client);
    nc_server_config_del_auth_client_pam_name(auth_client);
    nc_server_config_del_auth_client_pam_dir(auth_client);
    nc_server_config_del_auth_client_username(auth_client);

    opts->client_count--;
    if (!opts->client_count) {
        free(opts->auth_clients);
        opts->auth_clients = NULL;
    }
}

static void
nc_server_config_del_ssh(struct nc_bind *bind, struct nc_server_ssh_opts *opts)
{
    uint16_t i, hostkey_count, client_count;

    nc_server_config_del_local_address(bind);
    if (bind->sock > -1) {
        close(bind->sock);
    }

    /* store in variable because it gets decremented in the function call */
    hostkey_count = opts->hostkey_count;
    for (i = 0; i < hostkey_count; i++) {
        nc_server_config_del_hostkey(opts, &opts->hostkeys[i]);
    }

    client_count = opts->client_count;
    for (i = 0; i < client_count; i++) {
        nc_server_config_del_auth_client(opts, &opts->auth_clients[i]);
    }

    nc_server_config_del_hostkey_algs(opts);
    nc_server_config_del_kex_algs(opts);
    nc_server_config_del_encryption_algs(opts);
    nc_server_config_del_mac_algs(opts);

    free(opts);
    opts = NULL;
}

void
nc_server_config_del_endpt_ssh(struct nc_endpt *endpt, struct nc_bind *bind)
{
    nc_server_config_del_endpt_name(endpt);
    nc_server_config_del_ssh(bind, endpt->opts.ssh);

    server_opts.endpt_count--;
    if (!server_opts.endpt_count) {
        free(server_opts.endpts);
        free(server_opts.binds);
        server_opts.endpts = NULL;
        server_opts.binds = NULL;
    }
}

void
nc_server_config_del_unix_socket(struct nc_bind *bind, struct nc_server_unix_opts *opts)
{
    if (bind->sock > -1) {
        close(bind->sock);
    }

    free(bind->address);
    free(opts->address);

    free(opts);
    opts = NULL;
}

void
nc_server_config_del_endpt_unix_socket(struct nc_endpt *endpt, struct nc_bind *bind)
{
    nc_server_config_del_endpt_name(endpt);
    nc_server_config_del_unix_socket(bind, endpt->opts.unixsock);

    server_opts.endpt_count--;
    if (!server_opts.endpt_count) {
        free(server_opts.endpts);
        free(server_opts.binds);
        server_opts.endpts = NULL;
        server_opts.binds = NULL;
    }
}

/* presence container */
int
nc_server_config_listen(struct lyd_node *node, NC_OPERATION op)
{
    uint16_t i;

    (void) node;

    assert(op == NC_OP_CREATE || op == NC_OP_DELETE);

    if (op == NC_OP_DELETE) {
        for (i = 0; i < server_opts.endpt_count; i++) {
            switch (server_opts.endpts[i].ti) {
#ifdef NC_ENABLED_SSH
            case NC_TI_LIBSSH:
                nc_server_config_del_endpt_ssh(&server_opts.endpts[i], &server_opts.binds[i]);
                break;
#endif
#ifdef NC_ENABLED_TLS
            case NC_TI_OPENSSL:
                /* todo */
                break;
#endif
            case NC_TI_UNIX:
                nc_server_config_del_endpt_unix_socket(&server_opts.endpts[i], &server_opts.binds[i]);
                break;
            case NC_TI_NONE:
            case NC_TI_FD:
                ERRINT;
                return 1;
            }
        }
    }

    return 0;
}

/* default leaf */
static int
nc_server_config_idle_timeout(const struct lyd_node *node, NC_OPERATION op)
{
    assert(!strcmp(LYD_NAME(node), "idle-timeout"));

    if (equal_parent_name(node, 1, "listen")) {
        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            server_opts.idle_timeout = strtoul(lyd_get_value(node), NULL, 10);
        } else {
            /* default value */
            server_opts.idle_timeout = 3600;
        }
    }

    return 0;
}

static int
nc_server_config_create_bind(void)
{
    int ret = 0;
    void *tmp;

    tmp = realloc(server_opts.binds, (server_opts.endpt_count + 1) * sizeof *server_opts.binds);
    if (!tmp) {
        ERRMEM;
        ret = 1;
        goto cleanup;
    }
    server_opts.binds = tmp;
    memset(&server_opts.binds[server_opts.endpt_count], 0, sizeof *server_opts.binds);

    server_opts.binds[server_opts.endpt_count].sock = -1;

cleanup:
    return ret;
}

static int
nc_server_config_create_endpoint(const struct lyd_node *node)
{
    if (nc_server_config_create_bind()) {
        return 1;
    }

    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));

    return nc_server_config_realloc(lyd_get_value(node), (void **)&server_opts.endpts, sizeof *server_opts.endpts, &server_opts.endpt_count);
}

/* list */
static int
nc_server_config_endpoint(const struct lyd_node *node, NC_OPERATION op)
{
    int ret = 0;
    struct nc_endpt *endpt;
    struct nc_bind *bind;

    assert(!strcmp(LYD_NAME(node), "endpoint"));

    if (op == NC_OP_CREATE) {
        ret = nc_server_config_create_endpoint(node);
        if (ret) {
            goto cleanup;
        }
    } else if (op == NC_OP_DELETE) {
        /* free all children */
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }
        nc_server_config_del_endpt_ssh(endpt, bind);
    }

cleanup:
    return ret;
}

static int
nc_server_config_create_ssh(struct nc_endpt *endpt)
{
    endpt->ti = NC_TI_LIBSSH;
    endpt->opts.ssh = calloc(1, sizeof(struct nc_server_ssh_opts));
    if (!endpt->opts.ssh) {
        ERRMEM;
        return 1;
    }

    return 0;
}

/* NP container */
static int
nc_server_config_ssh(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "ssh"));

    if (nc_server_config_get_endpt(node, &endpt, &bind)) {
        ret = 1;
        goto cleanup;
    }

    if (op == NC_OP_CREATE) {
        ret = nc_server_config_create_ssh(endpt);
        if (ret) {
            goto cleanup;
        }
    } else if (op == NC_OP_DELETE) {
        nc_server_config_del_ssh(bind, endpt->opts.ssh);
    }

cleanup:
    return ret;
}

static int
nc_server_config_set_address_port(struct nc_endpt *endpt, struct nc_bind *bind, const char *address, uint16_t port)
{
    int sock = -1, set_addr, ret = 0;

    assert((address && !port) || (!address && port) || (endpt->ti == NC_TI_UNIX));

    if (address) {
        set_addr = 1;
    } else {
        set_addr = 0;
    }

    if (set_addr) {
        port = bind->port;
    } else {
        address = bind->address;
    }

    /* we have all the information we need to create a listening socket */
    if ((address && port) || (endpt->ti == NC_TI_UNIX)) {
        /* create new socket, close the old one */
        if (endpt->ti == NC_TI_UNIX) {
            sock = nc_sock_listen_unix(endpt->opts.unixsock);
        } else {
            sock = nc_sock_listen_inet(address, port, &endpt->ka);
        }

        if (sock == -1) {
            ret = 1;
            goto cleanup;
        }

        if (bind->sock > -1) {
            close(bind->sock);
        }
        bind->sock = sock;
    }

    if (sock > -1) {
        switch (endpt->ti) {
        case NC_TI_UNIX:
            VRB(NULL, "Listening on %s for UNIX connections.", endpt->opts.unixsock->address);
            break;
#ifdef NC_ENABLED_SSH
        case NC_TI_LIBSSH:
            VRB(NULL, "Listening on %s:%u for SSH connections.", address, port);
            break;
#endif
#ifdef NC_ENABLED_TLS
        case NC_TI_OPENSSL:
            VRB(NULL, "Listening on %s:%u for TLS connections.", address, port);
            break;
#endif
        default:
            ERRINT;
            ret = 1;
            break;
        }
    }

cleanup:
    return ret;
}

/* mandatory leaf */
static int
nc_server_config_local_address(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    (void) op;

    assert(!strcmp(LYD_NAME(node), "local-address"));

    if (equal_parent_name(node, 4, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }

        nc_server_config_del_local_address(bind);
        bind->address = strdup(lyd_get_value(node));
        if (!bind->address) {
            ERRMEM;
            ret = 1;
            goto cleanup;
        }

        ret = nc_server_config_set_address_port(endpt, bind, lyd_get_value(node), 0);
        if (ret) {
            goto cleanup;
        }
    }

cleanup:
    return ret;
}

/* leaf with default value */
static int
nc_server_config_local_port(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "local-port"));

    if (equal_parent_name(node, 4, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            bind->port = strtoul(lyd_get_value(node), NULL, 10);
        } else {
            /* delete -> set to default */
            bind->port = 0;
        }

        ret = nc_server_config_set_address_port(endpt, bind, NULL, bind->port);
        if (ret) {
            goto cleanup;
        }
    }

cleanup:
    return ret;
}

/* P container */
static int
nc_server_config_keepalives(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "keepalives"));

    if (equal_parent_name(node, 4, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }

        if (op == NC_OP_CREATE) {
            endpt->ka.enabled = 1;
        } else {
            endpt->ka.enabled = 0;
        }
        ret = nc_sock_configure_keepalive(bind->sock, &endpt->ka);
        if (ret) {
            goto cleanup;
        }
    }

cleanup:
    return ret;
}

/* mandatory leaf */
static int
nc_server_config_idle_time(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "idle-time"));

    if (equal_parent_name(node, 4, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            endpt->ka.idle_time = strtoul(lyd_get_value(node), NULL, 10);
        } else {
            endpt->ka.idle_time = 0;
        }
        ret = nc_sock_configure_keepalive(bind->sock, &endpt->ka);
        if (ret) {
            goto cleanup;
        }
    }

cleanup:
    return ret;
}

/* mandatory leaf */
static int
nc_server_config_max_probes(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "max-probes"));

    if (equal_parent_name(node, 4, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            endpt->ka.max_probes = strtoul(lyd_get_value(node), NULL, 10);
        } else {
            endpt->ka.max_probes = 0;
        }
        ret = nc_sock_configure_keepalive(bind->sock, &endpt->ka);
        if (ret) {
            goto cleanup;
        }
    }

cleanup:
    return ret;
}

/* mandatory leaf */
static int
nc_server_config_probe_interval(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "probe-interval"));

    if (equal_parent_name(node, 4, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, &bind)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            endpt->ka.probe_interval = strtoul(lyd_get_value(node), NULL, 10);
        } else {
            endpt->ka.probe_interval = 0;
        }
        ret = nc_sock_configure_keepalive(bind->sock, &endpt->ka);
        if (ret) {
            goto cleanup;
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_create_host_key(const struct lyd_node *node, struct nc_server_ssh_opts *opts)
{
    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));

    return nc_server_config_realloc(lyd_get_value(node), (void **)&opts->hostkeys, sizeof *opts->hostkeys, &opts->hostkey_count);
}

/* list */
static int
nc_server_config_host_key(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_hostkey *hostkey;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "host-key"));

    if ((equal_parent_name(node, 1, "server-identity")) && (equal_parent_name(node, 5, "listen"))) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (op == NC_OP_CREATE) {
            ret = nc_server_config_create_host_key(node, endpt->opts.ssh);
            if (ret) {
                goto cleanup;
            }
        } else if (op == NC_OP_DELETE) {
            if (nc_server_config_get_hostkey(node, endpt->opts.ssh, &hostkey)) {
                ret = 1;
                goto cleanup;
            }

            nc_server_config_del_hostkey(endpt->opts.ssh, hostkey);
        }
    } else if (equal_parent_name(node, 1, "transport-params")) {
        /* just a container with the name host-key, nothing to be done */
        goto cleanup;
    } else {
        ERRINT;
        ret = 1;
        goto cleanup;
    }

cleanup:
    return ret;
}

/* mandatory leaf */
static int
nc_server_config_public_key_format(const struct lyd_node *node, NC_OPERATION op)
{
    const char *format;
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    struct nc_public_key *pubkey;
    struct nc_hostkey *hostkey;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "public-key-format"));

    format = ((struct lyd_node_term *)node)->value.ident->name;

    if ((equal_parent_name(node, 6, "client-authentication")) && (equal_parent_name(node, 10, "listen"))) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_pubkey(node, auth_client, &pubkey)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            if (!strcmp(format, "ssh-public-key-format")) {
                pubkey->pubkey_type = NC_SSH_PUBKEY_SSH2;
            } else if (!strcmp(format, "subject-public-key-info-format")) {
                pubkey->pubkey_type = NC_SSH_PUBKEY_X509;
            } else {
                ERR(NULL, "Public key format (%s) not supported.", format);
            }
        }
    } else if ((equal_parent_name(node, 5, "server-identity")) && (equal_parent_name(node, 11, "listen"))) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_hostkey(node, endpt->opts.ssh, &hostkey)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            if (!strcmp(format, "ssh-public-key-format")) {
                hostkey->key.pubkey_type = NC_SSH_PUBKEY_SSH2;
            } else if (!strcmp(format, "subject-public-key-info-format")) {
                hostkey->key.pubkey_type = NC_SSH_PUBKEY_X509;
            } else {
                ERR(NULL, "Public key format (%s) not supported.", format);
            }
        }
    }

cleanup:
    return ret;
}

/* leaf */
static int
nc_server_config_private_key_format(const struct lyd_node *node, NC_OPERATION op)
{
    const char *format;
    struct nc_endpt *endpt;
    struct nc_hostkey *hostkey;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "private-key-format"));

    if (nc_server_config_get_endpt(node, &endpt, NULL)) {
        ret = 1;
        goto cleanup;
    }

    if (nc_server_config_get_hostkey(node, endpt->opts.ssh, &hostkey)) {
        ret = 1;
        goto cleanup;
    }

    format = ((struct lyd_node_term *)node)->value.ident->name;
    if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
        if (!strcmp(format, "rsa-private-key-format")) {
            hostkey->key.privkey_type = NC_PRIVKEY_FORMAT_RSA;
        } else if (!strcmp(format, "ec-private-key-format")) {
            hostkey->key.privkey_type = NC_PRIVKEY_FORMAT_EC;
        } else if (!strcmp(format, "subject-private-key-info-format")) {
            hostkey->key.privkey_type = NC_PRIVKEY_FORMAT_PKCS8;
        } else if (!strcmp(format, "openssh-private-key-format")) {
            hostkey->key.privkey_type = NC_PRIVKEY_FORMAT_OPENSSH;
        } else {
            ERR(NULL, "Private key format (%s) not supported.", format);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_replace_cleartext_private_key(const struct lyd_node *node, struct nc_hostkey *hostkey)
{
    nc_server_config_del_private_key(hostkey);
    hostkey->key.priv_base64 = strdup(lyd_get_value(node));
    if (!hostkey->key.priv_base64) {
        ERRMEM;
        return 1;
    }

    return 0;
}

static int
nc_server_config_cleartext_private_key(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_hostkey *hostkey;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "cleartext-private-key"));

    if ((equal_parent_name(node, 6, "ssh")) && (equal_parent_name(node, 8, "listen"))) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }
        if (nc_server_config_get_hostkey(node, endpt->opts.ssh, &hostkey)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            ret = nc_server_config_replace_cleartext_private_key(node, hostkey);
            if (ret) {
                goto cleanup;
            }
        } else {
            nc_server_config_del_private_key(hostkey);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_create_keystore_reference(const struct lyd_node *node, struct nc_hostkey *hostkey)
{
    uint16_t i;
    struct nc_keystore *ks = &server_opts.keystore;

    /* lookup name */
    for (i = 0; i < ks->asym_key_count; i++) {
        if (!strcmp(lyd_get_value(node), ks->asym_keys[i].name)) {
            break;
        }
    }

    if (i == ks->asym_key_count) {
        ERR(NULL, "Keystore \"%s\" not found.", lyd_get_value(node));
        return 1;
    }

    hostkey->ks_ref = &ks->asym_keys[i];

    return 0;
}

/* leaf */
static int
nc_server_config_keystore_reference(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_hostkey *hostkey;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "keystore-reference"));

    if ((equal_parent_name(node, 3, "server-identity")) && (equal_parent_name(node, 7, "listen"))) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }
        if (nc_server_config_get_hostkey(node, endpt->opts.ssh, &hostkey)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            /* set to keystore */
            hostkey->store = NC_STORE_KEYSTORE;

            ret = nc_server_config_create_keystore_reference(node, hostkey);
            if (ret) {
                goto cleanup;
            }
        } else {
            hostkey->ks_ref = NULL;
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_create_auth_key_public_key_list(const struct lyd_node *node, struct nc_client_auth *auth_client)
{
    assert(!strcmp(LYD_NAME(node), "public-key"));

    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));

    return nc_server_config_realloc(lyd_get_value(node), (void **)&auth_client->pubkeys, sizeof *auth_client->pubkeys, &auth_client->pubkey_count);
}

static int
nc_server_config_replace_auth_key_public_key_leaf(const struct lyd_node *node, struct nc_public_key *pubkey)
{
    nc_server_config_del_auth_client_pubkey_pub_base64(pubkey);

    pubkey->pub_base64 = strdup(lyd_get_value(node));
    if (!pubkey->pub_base64) {
        ERRMEM;
        return 1;
    }

    return 0;
}

static int
nc_server_config_replace_host_key_public_key(const struct lyd_node *node, struct nc_hostkey *hostkey)
{
    nc_server_config_del_public_key(hostkey);

    hostkey->key.pub_base64 = strdup(lyd_get_value(node));
    if (!hostkey->key.pub_base64) {
        ERRMEM;
        return 1;
    }

    return 0;
}

static int
nc_server_config_public_key(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_hostkey *hostkey;
    struct nc_client_auth *auth_client;
    struct nc_public_key *pubkey;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "public-key"));

    if ((equal_parent_name(node, 3, "host-key")) && (equal_parent_name(node, 8, "listen"))) {
        /* server's public-key, mandatory leaf */
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_hostkey(node, endpt->opts.ssh, &hostkey)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            /* set to local */
            hostkey->store = NC_STORE_LOCAL;

            ret = nc_server_config_replace_host_key_public_key(node, hostkey);
            if (ret) {
                goto cleanup;
            }
        }
    } else if ((equal_parent_name(node, 5, "client-authentication")) && (equal_parent_name(node, 9, "listen"))) {
        /* client auth pubkeys, list */
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if (op == NC_OP_CREATE) {
            /* set to local */
            auth_client->store = NC_STORE_LOCAL;

            ret = nc_server_config_create_auth_key_public_key_list(node, auth_client);
            if (ret) {
                goto cleanup;
            }
        } else if (op == NC_OP_DELETE) {
            if (nc_server_config_get_pubkey(node, auth_client, &pubkey)) {
                ret = 1;
                goto cleanup;
            }

            nc_server_config_del_auth_client_pubkey(auth_client, pubkey);
        }
    } else if ((equal_parent_name(node, 6, "client-authentication")) && (equal_parent_name(node, 10, "listen"))) {
        /* client auth pubkey, leaf */
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_pubkey(node, auth_client, &pubkey)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            ret = nc_server_config_replace_auth_key_public_key_leaf(node, pubkey);
            if (ret) {
                goto cleanup;
            }
        } else {
            nc_server_config_del_auth_client_pubkey_pub_base64(pubkey);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_create_user(const struct lyd_node *node, struct nc_server_ssh_opts *opts)
{
    node = lyd_child(node);
    assert(!strcmp(LYD_NAME(node), "name"));

    return nc_server_config_realloc(lyd_get_value(node), (void **)&opts->auth_clients, sizeof *opts->auth_clients, &opts->client_count);
}

/* list */
static int
nc_server_config_user(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "user"));

    if (equal_parent_name(node, 6, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (op == NC_OP_CREATE) {
            ret = nc_server_config_create_user(node, endpt->opts.ssh);
            if (ret) {
                goto cleanup;
            }
        } else if (op == NC_OP_DELETE) {
            if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
                ret = 1;
                goto cleanup;
            }

            nc_server_config_del_auth_client(endpt->opts.ssh, auth_client);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_auth_attempts(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "auth-attempts"));

    if (equal_parent_name(node, 5, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            endpt->opts.ssh->auth_attempts = strtoul(lyd_get_value(node), NULL, 10);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_auth_timeout(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "auth-timeout"));

    if (equal_parent_name(node, 5, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            endpt->opts.ssh->auth_timeout = strtoul(lyd_get_value(node), NULL, 10);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_replace_truststore_reference(const struct lyd_node *node, struct nc_client_auth *client_auth)
{
    uint16_t i;
    struct nc_truststore *ts = &server_opts.truststore;

    /* lookup name */
    for (i = 0; i < ts->pub_bag_count; i++) {
        if (!strcmp(lyd_get_value(node), ts->pub_bags[i].name)) {
            break;
        }
    }

    if (i == ts->pub_bag_count) {
        ERR(NULL, "Truststore \"%s\" not found.", lyd_get_value(node));
        return 1;
    }

    client_auth->ts_ref = &ts->pub_bags[i];

    return 0;
}

/* leaf */
static int
nc_server_config_truststore_reference(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "truststore-reference"));

    if ((equal_parent_name(node, 1, "public-keys")) && (equal_parent_name(node, 8, "listen"))) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            /* set to truststore */
            auth_client->store = NC_STORE_TRUSTSTORE;

            ret = nc_server_config_replace_truststore_reference(node, auth_client);
            if (ret) {
                goto cleanup;
            }
        } else {
            auth_client->ts_ref = NULL;
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_replace_password(const struct lyd_node *node, struct nc_client_auth *auth_client)
{
    nc_server_config_del_auth_client_password(auth_client);

    auth_client->password = strdup(lyd_get_value(node));
    if (!auth_client->password) {
        ERRMEM;
        return 1;
    }

    return 0;
}

/* leaf */
static int
nc_server_config_password(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "password"));

    if (equal_parent_name(node, 7, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            ret = nc_server_config_replace_password(node, auth_client);
            if (ret) {
                goto cleanup;
            }
        } else {
            nc_server_config_del_auth_client_password(auth_client);
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_pam_name(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "pam-config-file-name"));

    if (equal_parent_name(node, 8, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            nc_server_config_del_auth_client_pam_name(auth_client);

            auth_client->pam_config_name = strdup(lyd_get_value(node));
            if (!auth_client->pam_config_name) {
                ERRMEM;
                ret = 1;
                goto cleanup;
            }
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_pam_dir(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "pam-config-file-dir"));

    if (equal_parent_name(node, 8, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
            nc_server_config_del_auth_client_pam_dir(auth_client);
            auth_client->pam_config_dir = strdup(lyd_get_value(node));
            if (!auth_client->pam_config_dir) {
                ERRMEM;
                ret = 1;
                goto cleanup;
            }
        }
    }

cleanup:
    return ret;
}

/* leaf */
static int
nc_server_config_none(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    struct nc_client_auth *auth_client;
    int ret = 0;

    assert(!strcmp(LYD_NAME(node), "none"));

    if (equal_parent_name(node, 7, "listen")) {
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }

        if (nc_server_config_get_auth_client(node, endpt->opts.ssh, &auth_client)) {
            ret = 1;
            goto cleanup;
        }

        if (op == NC_OP_CREATE) {
            auth_client->supports_none = 1;
        } else {
            auth_client->supports_none = 0;
        }
    }

cleanup:
    return ret;
}

static int
nc_server_config_transport_params(const char *alg, char **alg_store, NC_OPERATION op)
{
    int ret = 0, alg_found = 0;
    char *substr, *haystack;
    size_t alg_len = strlen(alg);

    if ((op == NC_OP_CREATE) || (op == NC_OP_REPLACE)) {
        if (!*alg_store) {
            /* first call */
            *alg_store = strdup(alg);
            if (!*alg_store) {
                ERRMEM;
                ret = 1;
                goto cleanup;
            }
        } else {
            /* +1 because of ',' between algorithms */
            *alg_store = nc_realloc(*alg_store, strlen(*alg_store) + alg_len + 1 + 1);
            if (!*alg_store) {
                ERRMEM;
                ret = 1;
                goto cleanup;
            }
            sprintf(*alg_store, "%s,%s", *alg_store, alg);
        }
    } else {
        /* delete */
        haystack = *alg_store;
        while ((substr = strstr(haystack, alg))) {
            /* iterate over all the substrings */
            if (((substr == haystack) && (*(substr + alg_len) == ',')) ||
                    ((substr != haystack) && (*(substr - 1) == ',') && (*(substr + alg_len) == ','))) {
                /* either the first element of the string or somewhere in the middle */
                memmove(substr, substr + alg_len + 1, strlen(substr + alg_len + 1));
                alg_found = 1;
                break;
            } else if ((*(substr - 1) == ',') && (*(substr + alg_len) == '\0')) {
                /* the last element of the string */
                *(substr - 1) = '\0';
                alg_found = 1;
                break;
            }
            haystack++;
        }
        if (!alg_found) {
            ERR(NULL, "Unable to delete an algorithm (%s), which was not previously added.", alg);
            ret = 1;
        }
    }

cleanup:
    return ret;
}

/* leaf-list */
static int
nc_server_config_host_key_alg(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    int ret = 0, listen = 0;
    const char *alg;
    uint8_t i;

    /* get the algorithm name and compare it with algs supported by libssh */
    alg = ((struct lyd_node_term *)node)->value.ident->name;

    if (equal_parent_name(node, 6, "listen")) {
        listen = 1;
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }
    }

    i = 0;
    while (supported_hostkey_algs[i]) {
        if (!strcmp(supported_hostkey_algs[i], alg)) {
            if (listen) {
                if (nc_server_config_transport_params(alg, &endpt->opts.ssh->hostkey_algs, op)) {
                    ret = 1;
                    goto cleanup;
                }
            }
            break;
        }
        i++;
    }
    if (!supported_hostkey_algs[i]) {
        /* algorithm not supported */
        ERR(NULL, "Public key algorithm (%s) not supported by libssh.", alg);
        ret = 1;
    }

cleanup:
    return ret;
}

/* leaf-list */
static int
nc_server_config_kex_alg(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    int ret = 0, listen = 0;
    const char *alg;
    uint8_t i;

    /* get the algorithm name and compare it with algs supported by libssh */
    alg = ((struct lyd_node_term *)node)->value.ident->name;

    if (equal_parent_name(node, 6, "listen")) {
        listen = 1;
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }
    }

    i = 0;
    while (supported_kex_algs[i]) {
        if (!strcmp(supported_kex_algs[i], alg)) {
            if (listen) {
                if (nc_server_config_transport_params(alg, &endpt->opts.ssh->kex_algs, op)) {
                    ret = 1;
                    goto cleanup;
                }
            }
            break;
        }
        i++;
    }
    if (!supported_kex_algs[i]) {
        /* algorithm not supported */
        ERR(NULL, "Key exchange algorithm (%s) not supported by libssh.", alg);
        ret = 1;
    }

cleanup:
    return ret;
}

/* leaf-list */
static int
nc_server_config_encryption_alg(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    int ret = 0, listen = 0;
    const char *alg;
    uint8_t i;

    /* get the algorithm name and compare it with algs supported by libssh */
    alg = ((struct lyd_node_term *)node)->value.ident->name;

    if (equal_parent_name(node, 6, "listen")) {
        listen = 1;
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }
    }

    i = 0;
    while (supported_encryption_algs[i]) {
        if (!strcmp(supported_encryption_algs[i], alg)) {
            if (listen) {
                if (nc_server_config_transport_params(alg, &endpt->opts.ssh->encryption_algs, op)) {
                    ret = 1;
                    goto cleanup;
                }
            }
            break;
        }
        i++;
    }
    if (!supported_encryption_algs[i]) {
        /* algorithm not supported */
        ERR(NULL, "Encryption algorithm (%s) not supported by libssh.", alg);
        ret = 1;
    }

cleanup:
    return ret;
}

/* leaf-list */
static int
nc_server_config_mac_alg(const struct lyd_node *node, NC_OPERATION op)
{
    struct nc_endpt *endpt;
    int ret = 0, listen = 0;
    const char *alg;
    uint8_t i;

    /* get the algorithm name and compare it with algs supported by libssh */
    alg = ((struct lyd_node_term *)node)->value.ident->name;

    if (equal_parent_name(node, 6, "listen")) {
        listen = 1;
        if (nc_server_config_get_endpt(node, &endpt, NULL)) {
            ret = 1;
            goto cleanup;
        }
    }

    i = 0;
    while (supported_mac_algs[i]) {
        if (!strcmp(supported_mac_algs[i], alg)) {
            if (listen) {
                if (nc_server_config_transport_params(alg, &endpt->opts.ssh->mac_algs, op)) {
                    ret = 1;
                    goto cleanup;
                }
            }
            break;
        }
        i++;
    }
    if (!supported_mac_algs[i]) {
        /* algorithm not supported */
        ERR(NULL, "MAC algorithm (%s) not supported by libssh.", alg);
        ret = 1;
    }

cleanup:
    return ret;
}

static int
nc_server_config_create_unix_socket(struct nc_endpt *endpt)
{
    endpt->ti = NC_TI_UNIX;
    endpt->opts.unixsock = calloc(1, sizeof *endpt->opts.unixsock);
    if (!endpt->opts.unixsock) {
        ERRMEM;
        return 1;
    }

    /* set default values */
    endpt->opts.unixsock->mode = -1;
    endpt->opts.unixsock->uid = -1;
    endpt->opts.unixsock->gid = -1;

    return 0;
}

static int
nc_server_config_unix_socket(const struct lyd_node *node, NC_OPERATION op)
{
    int ret = 0;
    uint32_t prev_lo;
    struct nc_endpt *endpt;
    struct nc_bind *bind;
    struct nc_server_unix_opts *opts;
    struct lyd_node *data = NULL;

    assert(!strcmp(LYD_NAME(node), "unix-socket"));

    if (nc_server_config_get_endpt(node, &endpt, &bind)) {
        ret = 1;
        goto cleanup;
    }

    if (op == NC_OP_CREATE) {
        if (nc_server_config_create_unix_socket(endpt)) {
            ret = 1;
            goto cleanup;
        }

        opts = endpt->opts.unixsock;

        lyd_find_path(node, "path", 0, &data);
        assert(data);

        opts->address = strdup(lyd_get_value(data));
        bind->address = strdup(lyd_get_value(data));
        if (!opts->address || !bind->address) {
            ERRMEM;
            ret = 1;
            goto cleanup;
        }

        /* silently search for non-mandatory parameters */
        prev_lo = ly_log_options(0);
        ret = lyd_find_path(node, "mode", 0, &data);
        if (!ret) {
            opts->mode = strtol(lyd_get_value(data), NULL, 8);
        }

        ret = lyd_find_path(node, "uid", 0, &data);
        if (!ret) {
            opts->uid = strtol(lyd_get_value(data), NULL, 10);
        }

        ret = lyd_find_path(node, "gid", 0, &data);
        if (!ret) {
            opts->gid = strtol(lyd_get_value(data), NULL, 10);
        }

        /* reset the logging options */
        ly_log_options(prev_lo);

        ret = nc_server_config_set_address_port(endpt, bind, NULL, 0);
        if (ret) {
            goto cleanup;
        }
    } else if (op == NC_OP_DELETE) {
        nc_server_config_del_unix_socket(bind, endpt->opts.unixsock);
    }

cleanup:
    return ret;
}

static int
nc_server_config_parse_netconf_server(const struct lyd_node *node, NC_OPERATION op)
{
    const char *name = LYD_NAME(node);

    if (!strcmp(name, "listen")) {
        if (nc_server_config_listen(NULL, op)) {
            goto error;
        }
    } else if (!strcmp(name, "idle-timeout")) {
        if (nc_server_config_idle_timeout(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "endpoint")) {
        if (nc_server_config_endpoint(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "ssh")) {
        if (nc_server_config_ssh(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "local-address")) {
        if (nc_server_config_local_address(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "local-port")) {
        if (nc_server_config_local_port(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "keepalives")) {
        if (nc_server_config_keepalives(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "idle-time")) {
        if (nc_server_config_idle_time(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "max-probes")) {
        if (nc_server_config_max_probes(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "probe-interval")) {
        if (nc_server_config_probe_interval(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "host-key")) {
        if (nc_server_config_host_key(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "public-key-format")) {
        if (nc_server_config_public_key_format(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "public-key")) {
        if (nc_server_config_public_key(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "private-key-format")) {
        if (nc_server_config_private_key_format(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "cleartext-private-key")) {
        if (nc_server_config_cleartext_private_key(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "keystore-reference")) {
        if (nc_server_config_keystore_reference(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "user")) {
        if (nc_server_config_user(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "auth-attempts")) {
        if (nc_server_config_auth_attempts(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "auth-timeout")) {
        if (nc_server_config_auth_timeout(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "truststore-reference")) {
        if (nc_server_config_truststore_reference(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "password")) {
        if (nc_server_config_password(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "pam-config-file-name")) {
        if (nc_server_config_pam_name(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "pam-config-file-dir")) {
        if (nc_server_config_pam_dir(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "none")) {
        if (nc_server_config_none(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "host-key-alg")) {
        if (nc_server_config_host_key_alg(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "key-exchange-alg")) {
        if (nc_server_config_kex_alg(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "encryption-alg")) {
        if (nc_server_config_encryption_alg(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "mac-alg")) {
        if (nc_server_config_mac_alg(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "unix-socket")) {
        if (nc_server_config_unix_socket(node, op)) {
            goto error;
        }
    } else if (!strcmp(name, "cert-data")) {} else if (!strcmp(name, "expiration-date")) {} else if (!strcmp(name, "asymmetric-key")) {} else if (!strcmp(name, "certificate")) {} else if (!strcmp(name, "key-format")) {} else if (!strcmp(name,
            "cleartext-key")) {} else if (!strcmp(name, "hidden-key")) {} else if (!strcmp(name, "id_hint")) {} else if (!strcmp(name, "external-identity")) {} else if (!strcmp(name, "hash")) {} else if (!strcmp(name, "context")) {} else if (!strcmp(name,
            "target-protocol")) {} else if (!strcmp(name, "target-kdf")) {} else if (!strcmp(name, "client-authentication")) {} else if (!strcmp(name, "ca-certs")) {} else if (!strcmp(name, "ee-certs")) {} else if (!strcmp(name,
            "raw-public-keys")) {} else if (!strcmp(name, "tls12-psks")) {} else if (!strcmp(name, "tls13-epsks")) {} else if (!strcmp(name, "tls-version")) {} else if (!strcmp(name, "cipher-suite")) {} else if (!strcmp(name,
            "peer-allowed-to-send")) {} else if (!strcmp(name, "test-peer-aliveness")) {} else if (!strcmp(name, "max-wait")) {} else if (!strcmp(name, "max-attempts")) {} else if (!strcmp(name, "cert-to-name")) {} else if (!strcmp(name,
            "id")) {} else if (!strcmp(name, "fingerprint")) {} else if (!strcmp(name, "map-type")) {}

    return 0;

error:
    ERR(NULL, "Configuring (%s) failed.", LYD_NAME(node));
    return 1;
}

int
nc_session_server_parse_tree(const struct lyd_node *node, NC_OPERATION parent_op, NC_MODULE module)
{
    struct lyd_node *child;
    struct lyd_meta *m;
    NC_OPERATION current_op = NC_OP_UNKNOWN;
    int ret;

    assert(node);

    /* get current op if there is any */
    if ((m = lyd_find_meta(node->meta, NULL, "yang:operation"))) {
        if (!strcmp(lyd_get_meta_value(m), "create")) {
            current_op = NC_OP_CREATE;
        } else if (!strcmp(lyd_get_meta_value(m), "delete")) {
            current_op = NC_OP_DELETE;
        } else if (!strcmp(lyd_get_meta_value(m), "replace")) {
            current_op = NC_OP_REPLACE;
        } else if (!strcmp(lyd_get_meta_value(m), "none")) {
            current_op = NC_OP_NONE;
        }
    }

    /* node has no op, inherit from the parent */
    if (!current_op) {
        if (!parent_op) {
            ERR(NULL, "Unknown operation for node \"%s\".", LYD_NAME(node));
            return 1;
        }

        current_op = parent_op;
    }

    switch (current_op) {
    case NC_OP_NONE:
        break;
    case NC_OP_CREATE:
    case NC_OP_DELETE:
    case NC_OP_REPLACE:
        if (module == NC_MODULE_NETCONF_SERVER) {
            ret = nc_server_config_parse_netconf_server(node, current_op);
        } else if (module == NC_MODULE_KEYSTORE) {
            ret = nc_server_config_parse_keystore(node, current_op);
        } else {
            ret = nc_server_config_parse_truststore(node, current_op);
        }
        if (ret) {
            return ret;
        }
        break;
    default:
        break;
    }

    if (current_op != NC_OP_DELETE) {
        LY_LIST_FOR(lyd_child(node), child) {
            if (nc_session_server_parse_tree(child, current_op, module)) {
                return 1;
            }
        }
    }
    return 0;
}

API int
nc_server_config_load_modules(struct ly_ctx **ctx)
{
    int i, new_ctx = 0;

    if (!*ctx) {
        if (ly_ctx_new(NC_SERVER_SEARCH_DIR, 0, ctx)) {
            ERR(NULL, "Couldn't create new libyang context.\n");
            goto error;
        }
        new_ctx = 1;
    }

    /* all features */
    const char *ietf_nectonf_server[] = {"ssh-listen", "tls-listen", "ssh-call-home", "tls-call-home", "central-netconf-server-supported", NULL};
    /* all features */
    const char *ietf_x509_cert_to_name[] = {NULL};
    /* no private-key-encryption and csr-generation */
    const char *ietf_crypto_types[] = {
        "one-symmetric-key-format", "one-asymmetric-key-format", "symmetrically-encrypted-value-format",
        "asymmetrically-encrypted-value-format", "cms-enveloped-data-format", "cms-encrypted-data-format",
        "p10-based-csrs", "certificate-expiration-notification", "hidden-keys", "password-encryption",
        "symmetric-key-encryption", NULL
    };
    /* all features */
    const char *ietf_tcp_common[] = {"keepalives-supported", NULL};
    /* no ssh-x509-certs */
    const char *ietf_ssh_common[] = {"transport-params", "public-key-generation", NULL};
    /* all features */
    const char *iana_ssh_encryption_algs[] = {NULL};
    /* all features */
    const char *iana_ssh_key_exchange_algs[] = {NULL};
    /* all features */
    const char *iana_ssh_mac_algs[] = {NULL};
    /* all features */
    const char *iana_ssh_public_key_algs[] = {NULL};
    /* no symmetric-keys */
    const char *ietf_keystore[] = {"central-keystore-supported", "local-definitions-supported", "asymmetric-keys", NULL};
    /* no ssh-server-keepalives and local-user-auth-hostbased */
    const char *ietf_ssh_server[] = {"local-users-supported", "local-user-auth-publickey", "local-user-auth-password", "local-user-auth-none", NULL};
    /* all features */
    const char *ietf_truststore[] = {"central-truststore-supported", "local-definitions-supported", "certificates", "public-keys", NULL};
    /* all features */
    const char *ietf_tls_server[] = {
        "tls-server-keepalives", "server-ident-x509-cert", "server-ident-raw-public-key", "server-ident-tls12-psk",
        "server-ident-tls13-epsk", "client-auth-supported", "client-auth-x509-cert", "client-auth-raw-public-key",
        "client-auth-tls12-psk", "client-auth-tls13-epsk", NULL
    };
    /* all features */
    const char *libnetconf2_netconf_server[] = {NULL};

    const char *module_names[] = {
        "ietf-netconf-server", "ietf-x509-cert-to-name", "ietf-crypto-types",
        "ietf-tcp-common", "ietf-ssh-common", "iana-ssh-encryption-algs",
        "iana-ssh-key-exchange-algs", "iana-ssh-mac-algs", "iana-ssh-public-key-algs",
        "ietf-keystore", "ietf-ssh-server", "ietf-truststore",
        "ietf-tls-server", "libnetconf2-netconf-server", NULL
    };

    const char **module_features[] = {
        ietf_nectonf_server, ietf_x509_cert_to_name, ietf_crypto_types,
        ietf_tcp_common, ietf_ssh_common, iana_ssh_encryption_algs,
        iana_ssh_key_exchange_algs, iana_ssh_mac_algs, iana_ssh_public_key_algs,
        ietf_keystore, ietf_ssh_server, ietf_truststore,
        ietf_tls_server, libnetconf2_netconf_server, NULL
    };

    for (i = 0; module_names[i] != NULL; i++) {
        if (!ly_ctx_load_module(*ctx, module_names[i], NULL, module_features[i])) {
            ERR(NULL, "Loading module \"%s\" failed.\n", module_names[i]);
            goto error;
        }
    }

    return 0;

error:
    if (new_ctx) {
        ly_ctx_destroy(*ctx);
        *ctx = NULL;
    }
    return 1;
}

API int
nc_server_config_setup_path(const struct ly_ctx *ctx, const char *path)
{
    struct lyd_node *tree = NULL;
    int ret = 0;

    NC_CHECK_ARG_RET(NULL, path, 1);

    ret = lyd_parse_data_path(ctx, path, LYD_XML, LYD_PARSE_NO_STATE | LYD_PARSE_STRICT, LYD_VALIDATE_NO_STATE, &tree);
    if (ret) {
        goto cleanup;
    }

    ret = nc_server_config_setup(tree);
    if (ret) {
        goto cleanup;
    }

cleanup:
    lyd_free_all(tree);
    return ret;
}

static int
nc_server_config_fill_nectonf_server(const struct lyd_node *data, NC_OPERATION op)
{
    int ret = 0;
    struct lyd_node *tree;

    ret = lyd_find_path(data, "/ietf-netconf-server:netconf-server", 0, &tree);
    if (ret) {
        ERR(NULL, "Unable to find the netconf-server container in the YANG data.");
        goto cleanup;
    }

    if (nc_session_server_parse_tree(tree, op, NC_MODULE_NETCONF_SERVER)) {
        ret = 1;
        goto cleanup;
    }

cleanup:
    return ret;
}

API int
nc_server_config_setup(const struct lyd_node *data)
{
    int ret = 0;

    /* LOCK */
    pthread_rwlock_wrlock(&server_opts.config_lock);

    /* configure keystore */
    ret = nc_server_config_fill_keystore(data, NC_OP_UNKNOWN);
    if (ret) {
        ERR(NULL, "Filling keystore failed.");
        goto cleanup;
    }

    /* configure truststore */
    ret = nc_server_config_fill_truststore(data, NC_OP_UNKNOWN);
    if (ret) {
        ERR(NULL, "Filling truststore failed.");
        goto cleanup;
    }

    /* configure netconf-server */
    ret = nc_server_config_fill_nectonf_server(data, NC_OP_UNKNOWN);
    if (ret) {
        ERR(NULL, "Filling netconf-server failed.");
        goto cleanup;
    }

cleanup:
    /* UNLOCK */
    pthread_rwlock_unlock(&server_opts.config_lock);
    return ret;
}

API int
nc_server_config_setup2(const struct lyd_node *data)
{
    int ret = 0;
    struct lyd_node *tree, *iter, *root;

    /* LOCK */
    pthread_rwlock_wrlock(&server_opts.config_lock);

    /* find the netconf-server node */
    ret = lyd_find_path(data, "/ietf-netconf-server:netconf-server", 0, &root);
    if (ret) {
        ERR(NULL, "Unable to find the netconf-server container in the YANG data.");
        goto cleanup;
    }

    /* iterate through all the nodes and make sure there is no operation attribute */
    LY_LIST_FOR(root, tree) {
        LYD_TREE_DFS_BEGIN(tree, iter) {
            if (lyd_find_meta(iter->meta, NULL, "yang:operation")) {
                ERR(NULL, "Unexpected operation attribute in the YANG data.");
                ret = 1;
                goto cleanup;
            }
            LYD_TREE_DFS_END(tree, iter);
        }
    }

    /* delete the current configuration */
    nc_server_config_listen(NULL, NC_OP_DELETE);
    nc_server_config_ks_keystore(NULL, NC_OP_DELETE);
    nc_server_config_ts_truststore(NULL, NC_OP_DELETE);

    /* configure keystore */
    ret = nc_server_config_fill_keystore(data, NC_OP_CREATE);
    if (ret) {
        ERR(NULL, "Filling keystore failed.");
        goto cleanup;
    }

    /* configure truststore */
    ret = nc_server_config_fill_truststore(data, NC_OP_CREATE);
    if (ret) {
        ERR(NULL, "Filling truststore failed.");
        goto cleanup;
    }

    /* configure netconf-server */
    ret = nc_server_config_fill_nectonf_server(data, NC_OP_CREATE);
    if (ret) {
        ERR(NULL, "Filling netconf-server failed.");
        goto cleanup;
    }

cleanup:
    /* UNLOCK */
    pthread_rwlock_unlock(&server_opts.config_lock);
    return ret;
}