/* SPDX-License-Identifier: BSD-3-Clause */
/*
 * Copyright (c) 1995 Danny Gasparovski.
 */

#include "slirp.h"

inline void
insque(void *a, void *b)
{
	register struct quehead *element = (struct quehead *) a;
	register struct quehead *head = (struct quehead *) b;
	element->qh_link = head->qh_link;
	head->qh_link = (struct quehead *)element;
	element->qh_rlink = (struct quehead *)head;
	((struct quehead *)(element->qh_link))->qh_rlink
	= (struct quehead *)element;
}

inline void
remque(void *a)
{
  register struct quehead *element = (struct quehead *) a;
  ((struct quehead *)(element->qh_link))->qh_rlink = element->qh_rlink;
  ((struct quehead *)(element->qh_rlink))->qh_link = element->qh_link;
  element->qh_rlink = NULL;
}

/* TODO: IPv6 */
struct gfwd_list *
add_guestfwd(struct gfwd_list **ex_ptr,
             SlirpWriteCb write_cb, void *opaque,
             struct in_addr addr, int port)
{
    struct gfwd_list *f = g_new0(struct gfwd_list, 1);

    f->write_cb = write_cb;
    f->opaque = opaque;
    f->ex_fport = port;
    f->ex_addr = addr;
    f->ex_next = *ex_ptr;
    *ex_ptr = f;

    return f;
}

struct gfwd_list *
add_exec(struct gfwd_list **ex_ptr, const char *cmdline,
         struct in_addr addr, int port)
{
    struct gfwd_list *f = add_guestfwd(ex_ptr, NULL, NULL, addr, port);

    f->ex_exec = g_strdup(cmdline);

    return f;
}

static int
slirp_socketpair_with_oob(int sv[2])
{
    struct sockaddr_in addr = {
        .sin_family = AF_INET,
        .sin_port = 0,
        .sin_addr.s_addr = INADDR_ANY,
    };
    socklen_t addrlen = sizeof(addr);
    int ret, s;

    sv[1] = -1;
    s = slirp_socket(AF_INET, SOCK_STREAM, 0);
    if (s < 0 || bind(s, (struct sockaddr *)&addr, addrlen) < 0 ||
        listen(s, 1) < 0 ||
        getsockname(s, (struct sockaddr *)&addr, &addrlen) < 0) {
        goto err;
    }

    sv[1] = slirp_socket(AF_INET, SOCK_STREAM, 0);
    if (sv[1] < 0) {
        goto err;
    }
    /*
     * This connect won't block because we've already listen()ed on
     * the server end (even though we won't accept() the connection
     * until later on).
     */
    do {
        ret = connect(sv[1], (struct sockaddr *)&addr, addrlen);
    } while (ret < 0 && errno == EINTR);
    if (ret < 0) {
        goto err;
    }

    do {
        sv[0] = accept(s, (struct sockaddr *)&addr, &addrlen);
    } while (sv[0] < 0 && errno == EINTR);
    if (sv[0] < 0) {
        goto err;
    }

    closesocket(s);
    return 0;

err:
    g_critical("slirp_socketpair(): %s", strerror(errno));
    if (s >= 0) {
        closesocket(s);
    }
    if (sv[1] >= 0) {
        closesocket(sv[1]);
    }
    return -1;
}

static void
fork_exec_child_setup(gpointer data)
{
#ifndef _WIN32
    setsid();
#endif
}

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"

#if !GLIB_CHECK_VERSION(2, 58, 0)
typedef struct SlirpGSpawnFds {
    GSpawnChildSetupFunc child_setup;
    gpointer user_data;
    gint stdin_fd;
    gint stdout_fd;
    gint stderr_fd;
} SlirpGSpawnFds;

static inline void
slirp_gspawn_fds_setup(gpointer user_data)
{
    SlirpGSpawnFds *q = (SlirpGSpawnFds *)user_data;

    dup2(q->stdin_fd, 0);
    dup2(q->stdout_fd, 1);
    dup2(q->stderr_fd, 2);
    q->child_setup(q->user_data);
}
#endif

static inline gboolean
g_spawn_async_with_fds_slirp(const gchar *working_directory,
                            gchar **argv,
                            gchar **envp,
                            GSpawnFlags flags,
                            GSpawnChildSetupFunc child_setup,
                            gpointer user_data,
                            GPid *child_pid,
                            gint stdin_fd,
                            gint stdout_fd,
                            gint stderr_fd,
                            GError **error)
{
#if GLIB_CHECK_VERSION(2, 58, 0)
    return g_spawn_async_with_fds(working_directory, argv, envp, flags,
                                  child_setup, user_data,
                                  child_pid, stdin_fd, stdout_fd, stderr_fd,
                                  error);
#else
    SlirpGSpawnFds setup = {
        .child_setup = child_setup,
        .user_data = user_data,
        .stdin_fd = stdin_fd,
        .stdout_fd = stdout_fd,
        .stderr_fd = stderr_fd,
    };

    return g_spawn_async(working_directory, argv, envp, flags,
                         slirp_gspawn_fds_setup, &setup,
                         child_pid, error);
#endif
}

#define g_spawn_async_with_fds(wd, argv, env, f, c, d, p, ifd, ofd, efd, err) \
    g_spawn_async_with_fds_slirp(wd, argv, env, f, c, d, p, ifd, ofd, efd, err)

#pragma GCC diagnostic pop

int
fork_exec(struct socket *so, const char *ex)
{
    GError *err = NULL;
    char **argv;
    int opt, sp[2];

    DEBUG_CALL("fork_exec");
    DEBUG_ARG("so = %p", so);
    DEBUG_ARG("ex = %p", ex);

    if (slirp_socketpair_with_oob(sp) < 0) {
        return 0;
    }

    argv = g_strsplit(ex, " ", -1);
    g_spawn_async_with_fds(NULL /* cwd */,
                           argv,
                           NULL /* env */,
                           G_SPAWN_SEARCH_PATH,
                           fork_exec_child_setup, NULL /* data */,
                           NULL /* child_pid */,
                           sp[1], sp[1], sp[1],
                           &err);
    g_strfreev(argv);

    if (err) {
        g_critical("fork_exec: %s", err->message);
        g_error_free(err);
        closesocket(sp[0]);
        closesocket(sp[1]);
        return 0;
    }

    so->s = sp[0];
    closesocket(sp[1]);
    slirp_socket_set_fast_reuse(so->s);
    opt = 1;
    setsockopt(so->s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(int));
    slirp_set_nonblock(so->s);
    so->slirp->cb->register_poll_fd(so->s, so->slirp->opaque);
    return 1;
}

char *slirp_connection_info(Slirp *slirp)
{
    GString *str = g_string_new(NULL);
    const char * const tcpstates[] = {
        [TCPS_CLOSED]       = "CLOSED",
        [TCPS_LISTEN]       = "LISTEN",
        [TCPS_SYN_SENT]     = "SYN_SENT",
        [TCPS_SYN_RECEIVED] = "SYN_RCVD",
        [TCPS_ESTABLISHED]  = "ESTABLISHED",
        [TCPS_CLOSE_WAIT]   = "CLOSE_WAIT",
        [TCPS_FIN_WAIT_1]   = "FIN_WAIT_1",
        [TCPS_CLOSING]      = "CLOSING",
        [TCPS_LAST_ACK]     = "LAST_ACK",
        [TCPS_FIN_WAIT_2]   = "FIN_WAIT_2",
        [TCPS_TIME_WAIT]    = "TIME_WAIT",
    };
    struct in_addr dst_addr;
    struct sockaddr_in src;
    socklen_t src_len;
    uint16_t dst_port;
    struct socket *so;
    const char *state;
    char buf[20];

    g_string_append_printf(str,
        "  Protocol[State]    FD  Source Address  Port   "
        "Dest. Address  Port RecvQ SendQ\n");

    /* TODO: IPv6 */

    for (so = slirp->tcb.so_next; so != &slirp->tcb; so = so->so_next) {
        if (so->so_state & SS_HOSTFWD) {
            state = "HOST_FORWARD";
        } else if (so->so_tcpcb) {
            state = tcpstates[so->so_tcpcb->t_state];
        } else {
            state = "NONE";
        }
        if (so->so_state & (SS_HOSTFWD | SS_INCOMING)) {
            src_len = sizeof(src);
            getsockname(so->s, (struct sockaddr *)&src, &src_len);
            dst_addr = so->so_laddr;
            dst_port = so->so_lport;
        } else {
            src.sin_addr = so->so_laddr;
            src.sin_port = so->so_lport;
            dst_addr = so->so_faddr;
            dst_port = so->so_fport;
        }
        snprintf(buf, sizeof(buf), "  TCP[%s]", state);
        g_string_append_printf(str, "%-19s %3d %15s %5d ", buf, so->s,
                       src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*",
                       ntohs(src.sin_port));
        g_string_append_printf(str, "%15s %5d %5d %5d\n",
                       inet_ntoa(dst_addr), ntohs(dst_port),
                       so->so_rcv.sb_cc, so->so_snd.sb_cc);
    }

    for (so = slirp->udb.so_next; so != &slirp->udb; so = so->so_next) {
        if (so->so_state & SS_HOSTFWD) {
            snprintf(buf, sizeof(buf), "  UDP[HOST_FORWARD]");
            src_len = sizeof(src);
            getsockname(so->s, (struct sockaddr *)&src, &src_len);
            dst_addr = so->so_laddr;
            dst_port = so->so_lport;
        } else {
            snprintf(buf, sizeof(buf), "  UDP[%d sec]",
                         (so->so_expire - curtime) / 1000);
            src.sin_addr = so->so_laddr;
            src.sin_port = so->so_lport;
            dst_addr = so->so_faddr;
            dst_port = so->so_fport;
        }
        g_string_append_printf(str, "%-19s %3d %15s %5d ", buf, so->s,
                       src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*",
                       ntohs(src.sin_port));
        g_string_append_printf(str, "%15s %5d %5d %5d\n",
                       inet_ntoa(dst_addr), ntohs(dst_port),
                       so->so_rcv.sb_cc, so->so_snd.sb_cc);
    }

    for (so = slirp->icmp.so_next; so != &slirp->icmp; so = so->so_next) {
        snprintf(buf, sizeof(buf), "  ICMP[%d sec]",
                     (so->so_expire - curtime) / 1000);
        src.sin_addr = so->so_laddr;
        dst_addr = so->so_faddr;
        g_string_append_printf(str, "%-19s %3d %15s  -    ", buf, so->s,
                       src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*");
        g_string_append_printf(str, "%15s  -    %5d %5d\n", inet_ntoa(dst_addr),
                       so->so_rcv.sb_cc, so->so_snd.sb_cc);
    }

    return g_string_free(str, FALSE);
}