// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <netinet/in.h>
#include "chan_user.h"
#include <os.h>
#include "port.h"
#include <um_malloc.h>

struct port_chan {
        int raw;
        struct termios tt;
        void *kernel_data;
        char dev[sizeof("32768\0")];
};

static void *port_init(char *str, int device, const struct chan_opts *opts)
{
        struct port_chan *data;
        void *kern_data;
        char *end;
        int port;

        if (*str != ':') {
                printk(UM_KERN_ERR "port_init : channel type 'port' must "
                       "specify a port number\n");
                return NULL;
        }
        str++;
        port = strtoul(str, &end, 0);
        if ((*end != '\0') || (end == str)) {
                printk(UM_KERN_ERR "port_init : couldn't parse port '%s'\n",
                       str);
                return NULL;
        }

        kern_data = port_data(port);
        if (kern_data == NULL)
                return NULL;

        data = uml_kmalloc(sizeof(*data), UM_GFP_KERNEL);
        if (data == NULL)
                goto err;

        *data = ((struct port_chan) { .raw              = opts->raw,
                                      .kernel_data      = kern_data });
        sprintf(data->dev, "%d", port);

        return data;
 err:
        port_kern_free(kern_data);
        return NULL;
}

static void port_free(void *d)
{
        struct port_chan *data = d;

        port_kern_free(data->kernel_data);
        kfree(data);
}

static int port_open(int input, int output, int primary, void *d,
                     char **dev_out)
{
        struct port_chan *data = d;
        int fd, err;

        fd = port_wait(data->kernel_data);
        if ((fd >= 0) && data->raw) {
                CATCH_EINTR(err = tcgetattr(fd, &data->tt));
                if (err)
                        return err;

                err = raw(fd);
                if (err)
                        return err;
        }
        *dev_out = data->dev;
        return fd;
}

static void port_close(int fd, void *d)
{
        struct port_chan *data = d;

        port_remove_dev(data->kernel_data);
        os_close_file(fd);
}

const struct chan_ops port_ops = {
        .type           = "port",
        .init           = port_init,
        .open           = port_open,
        .close          = port_close,
        .read           = generic_read,
        .write          = generic_write,
        .console_write  = generic_console_write,
        .window_size    = generic_window_size,
        .free           = port_free,
        .winch          = 1,
};

int port_listen_fd(int port)
{
        struct sockaddr_in addr;
        int fd, err, arg;

        fd = socket(PF_INET, SOCK_STREAM, 0);
        if (fd == -1)
                return -errno;

        arg = 1;
        if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &arg, sizeof(arg)) < 0) {
                err = -errno;
                goto out;
        }

        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
        if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
                err = -errno;
                goto out;
        }

        if (listen(fd, 1) < 0) {
                err = -errno;
                goto out;
        }

        err = os_set_fd_block(fd, 0);
        if (err < 0)
                goto out;

        return fd;
 out:
        close(fd);
        return err;
}

struct port_pre_exec_data {
        int sock_fd;
        int pipe_fd;
};

static void port_pre_exec(void *arg)
{
        struct port_pre_exec_data *data = arg;

        dup2(data->sock_fd, 0);
        dup2(data->sock_fd, 1);
        dup2(data->sock_fd, 2);
        close(data->sock_fd);
        dup2(data->pipe_fd, 3);
        shutdown(3, SHUT_RD);
        close(data->pipe_fd);
}

int port_connection(int fd, int *socket, int *pid_out)
{
        int new, err;
        char *env;
        char *argv[] = { "in.telnetd", "-L",
                         OS_LIB_PATH "/uml/port-helper", NULL };
        struct port_pre_exec_data data;

        if ((env = getenv("UML_PORT_HELPER")))
                argv[2] = env;

        new = accept(fd, NULL, 0);
        if (new < 0)
                return -errno;

        err = os_access(argv[2], X_OK);
        if (err < 0) {
                printk(UM_KERN_ERR "port_connection : error accessing port-helper "
                       "executable at %s: %s\n", argv[2], strerror(-err));
                if (env == NULL)
                        printk(UM_KERN_ERR "Set UML_PORT_HELPER environment "
                                "variable to path to uml-utilities port-helper "
                                "binary\n");
                goto out_close;
        }

        err = os_pipe(socket, 0, 0);
        if (err < 0)
                goto out_close;

        data = ((struct port_pre_exec_data)
                { .sock_fd              = new,
                  .pipe_fd              = socket[1] });

        err = run_helper(port_pre_exec, &data, argv);
        if (err < 0)
                goto out_shutdown;

        *pid_out = err;
        return new;

 out_shutdown:
        shutdown(socket[0], SHUT_RDWR);
        close(socket[0]);
        shutdown(socket[1], SHUT_RDWR);
        close(socket[1]);
 out_close:
        close(new);
        return err;
}