/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024 Hans Rosenfeld
 * Author: Hans Rosenfeld <rosenfeld@grumpf.hope-2000.org>
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <malloc_np.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>

#include "config.h"
#include "tpm_device.h"
#include "tpm_emul.h"

struct tpm_swtpm {
        int fd;
};

struct tpm_resp_hdr {
        uint16_t tag;
        uint32_t len;
        uint32_t errcode;
} __packed;

static int
tpm_swtpm_init(void **sc, nvlist_t *nvl)
{
        struct tpm_swtpm *tpm;
        const char *path;
        struct sockaddr_un tpm_addr;

        tpm = calloc(1, sizeof (struct tpm_swtpm));
        if (tpm == NULL) {
                warnx("%s: failed to allocate tpm_swtpm", __func__);
                return (ENOMEM);
        }

        path = get_config_value_node(nvl, "path");
        if (path == NULL) {
                warnx("%s: no socket path specified", __func__);
                return (ENOENT);
        }

        tpm->fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
        if (tpm->fd < 0) {
                warnx("%s: unable to open tpm socket", __func__);
                return (ENOENT);
        }

        bzero(&tpm_addr, sizeof (tpm_addr));
        tpm_addr.sun_family = AF_UNIX;
        strlcpy(tpm_addr.sun_path, path, sizeof (tpm_addr.sun_path) - 1);

        if (connect(tpm->fd, (struct sockaddr *)&tpm_addr, sizeof (tpm_addr)) ==
            -1) {
                warnx("%s: unable to connect to tpm socket \"%s\"", __func__,
                    path);
                return (ENOENT);
        }

        *sc = tpm;

        return (0);
}

static int
tpm_swtpm_execute_cmd(void *sc, void *cmd, uint32_t cmd_size, void *rsp,
    uint32_t rsp_size)
{
        struct tpm_swtpm *tpm;
        ssize_t len;

        if (rsp_size < (ssize_t)sizeof(struct tpm_resp_hdr)) {
                warn("%s: rsp_size of %u is too small", __func__, rsp_size);
                return (EINVAL);
        }

        tpm = sc;

        len = send(tpm->fd, cmd, cmd_size, MSG_NOSIGNAL|MSG_DONTWAIT);
        if (len == -1)
                err(1, "%s: cmd send failed, is swtpm running?", __func__);
        if (len != cmd_size) {
                warn("%s: cmd write failed (bytes written: %zd / %d)", __func__,
                    len, cmd_size);
                return (EFAULT);
        }

        len = recv(tpm->fd, rsp, rsp_size, 0);
        if (len == -1)
                err(1, "%s: rsp recv failed, is swtpm running?", __func__);
        if (len < (ssize_t)sizeof(struct tpm_resp_hdr)) {
                warn("%s: rsp read failed (bytes read: %zd / %d)", __func__,
                    len, rsp_size);
                return (EFAULT);
        }

        return (0);
}

static void
tpm_swtpm_deinit(void *sc)
{
        struct tpm_swtpm *tpm;

        tpm = sc;
        if (tpm == NULL)
                return;

        if (tpm->fd >= 0)
                close(tpm->fd);

        free(tpm);
}

static const struct tpm_emul tpm_emul_swtpm = {
        .name = "swtpm",
        .init = tpm_swtpm_init,
        .deinit = tpm_swtpm_deinit,
        .execute_cmd = tpm_swtpm_execute_cmd,
};
TPM_EMUL_SET(tpm_emul_swtpm);