/*
 * All rights reserved. See COPYRIGHT.
 *
 * IPC over socketpair between parent and children.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <time.h>
#include <unistd.h>

#include <atalk/dsi.h>
#include <atalk/errchk.h>
#include <atalk/globals.h>
#include <atalk/logger.h>
#include <atalk/server_child.h>
#include <atalk/server_ipc.h>
#include <atalk/util.h>

#define IPC_HEADERLEN 14
#define IPC_MAXMSGSIZE 90

typedef struct ipc_header {
    uint16_t command;
    pid_t	 child_pid;
    uid_t    uid;
    uint32_t len;
    char 	 *msg;
    int      afp_socket;
    uint16_t DSI_requestID;
} ipc_header_t;

static char *ipc_cmd_str[] = { "IPC_DISCOLDSESSION",
                               "IPC_GETSESSION",
                               "IPC_STATE",
                               "IPC_VOLUMES",
                               "IPC_LOGINDONE"
                             };

/*
 * Pass afp_socket to old disconnected session if one has a matching token (token = pid)
 * @returns -1 on error, 0 if no matching session was found, 1 if session was found and socket passed
 */
static int ipc_kill_token(struct ipc_header *ipc, server_child_t *children)
{
    pid_t pid;

    if (ipc->len != sizeof(pid_t)) {
        return -1;
    }

    /* assume signals SA_RESTART set */
    memcpy(&pid, ipc->msg, sizeof(pid_t));
    return server_child_transfer_session(children,
                                         pid,
                                         ipc->uid,
                                         ipc->afp_socket,
                                         ipc->DSI_requestID);
}

/* ----------------- */
static int ipc_get_session(struct ipc_header *ipc, server_child_t *children)
{
    uint32_t boottime;
    uint32_t idlen;
    char     *clientid, *p;

    if (ipc->len < (sizeof(idlen) + sizeof(boottime))) {
        return -1;
    }

    p = ipc->msg;
    memcpy(&idlen, p, sizeof(idlen));
    idlen = ntohl(idlen);
    p += sizeof(idlen);
    memcpy(&boottime, p, sizeof(boottime));
    p += sizeof(boottime);

    if (ipc->len < idlen + sizeof(idlen) + sizeof(boottime)) {
        return -1;
    }

    if (NULL == (clientid = (char *) malloc(idlen))) {
        return -1;
    }

    memcpy(clientid, p, idlen);
    LOG(log_debug, logtype_afpd, "ipc_get_session(pid: %u, uid: %u, time: 0x%08x)",
        ipc->child_pid, ipc->uid, boottime);
    server_child_kill_one_by_id(children,
                                ipc->child_pid,
                                ipc->uid,
                                idlen,
                                clientid,
                                boottime);
    return 0;
}

/* ----------------- */
static int ipc_login_done(const struct ipc_header *ipc,
                          server_child_t *children)
{
    LOG(log_debug, logtype_afpd, "ipc_login_done(pid: %u, uid: %u)",
        ipc->child_pid, ipc->uid);
    server_child_login_done(children,
                            ipc->child_pid,
                            ipc->uid);
    return 0;
}

static int ipc_set_state(struct ipc_header *ipc, server_child_t *children)
{
    EC_INIT;
    afp_child_t *child;
    pthread_mutex_lock(&children->servch_lock);

    if ((child = server_child_resolve(children, ipc->child_pid)) == NULL) {
        EC_FAIL;
    }

    memcpy(&child->afpch_state, ipc->msg, sizeof(uint16_t));
EC_CLEANUP:
    pthread_mutex_unlock(&children->servch_lock);
    EC_EXIT;
}

static int ipc_set_volumes(struct ipc_header *ipc, server_child_t *children)
{
    EC_INIT;
    afp_child_t *child;
    pthread_mutex_lock(&children->servch_lock);

    if ((child = server_child_resolve(children, ipc->child_pid)) == NULL) {
        EC_FAIL;
    }

    if (child->afpch_volumes) {
        free(child->afpch_volumes);
        child->afpch_volumes = NULL;
    }

    if (ipc->len) {
        child->afpch_volumes = strdup(ipc->msg);
    }

EC_CLEANUP:
    pthread_mutex_unlock(&children->servch_lock);
    EC_EXIT;
}

/***********************************************************************************
 * Public functions
 ***********************************************************************************/

/* -----------------
 * Ipc format
 * command
 * pid
 * uid
 *
 */

/*!
 * Read a IPC message from a child
 *
 * This is using an fd with non-blocking IO, so EAGAIN is not an error
 *
 * @args children  (rw) pointer to our structure with all childs
 * @args fd        (r)  IPC socket with child
 *
 * @returns -1 on error, 0 on success
 */
int ipc_server_read(server_child_t *children, int fd)
{
    int       ret;
    struct ipc_header ipc;
    char      buf[IPC_MAXMSGSIZE], *p;

    if ((ret = read(fd, buf, IPC_HEADERLEN)) != IPC_HEADERLEN) {
        if (ret != 0) {
            if (errno == EAGAIN) {
                return 0;
            }

            LOG(log_error, logtype_afpd,
                "Reading IPC header failed (%i of %u bytes read): %s",
                ret, IPC_HEADERLEN, strerror(errno));
        }

        return -1;
    }

    p = buf;
    memcpy(&ipc.command, p, sizeof(ipc.command));
    p += sizeof(ipc.command);
    memcpy(&ipc.child_pid, p, sizeof(ipc.child_pid));
    p += sizeof(ipc.child_pid);
    memcpy(&ipc.uid, p, sizeof(ipc.uid));
    p += sizeof(ipc.uid);
    memcpy(&ipc.len, p, sizeof(ipc.len));

    /* This should never happen */
    if (ipc.len > (IPC_MAXMSGSIZE - IPC_HEADERLEN)) {
        LOG(log_info, logtype_afpd, "IPC message exceeds allowed size (%u)", ipc.len);
        return -1;
    }

    memset(buf, 0, IPC_MAXMSGSIZE);

    if (ipc.len != 0) {
        if ((ret = read(fd, buf, ipc.len)) != (int) ipc.len) {
            LOG(log_info, logtype_afpd,
                "Reading IPC message failed (%u of %u  bytes read): %s",
                ret, ipc.len, strerror(errno));
            return -1;
        }
    }

    ipc.msg = buf;
    LOG(log_debug, logtype_afpd, "ipc_server_read(%s): pid: %u",
        ipc_cmd_str[ipc.command], ipc.child_pid);

    switch (ipc.command) {
    case IPC_DISCOLDSESSION:
        if (readt(fd, &ipc.DSI_requestID, 2, 0, 2) != 2) {
            LOG(log_error, logtype_afpd,
                "ipc_read(%s:child[%u]): couldn't read DSI id: %s",
                ipc_cmd_str[ipc.command], ipc.child_pid, strerror(errno));
            return -1;
        }

        if ((ipc.afp_socket = recv_fd(fd, 1)) == -1) {
            LOG(log_error, logtype_afpd, "ipc_read(%s:child[%u]): recv_fd: %s",
                ipc_cmd_str[ipc.command], ipc.child_pid, strerror(errno));
            return -1;
        }

        if (ipc_kill_token(&ipc, children) == 1) {
            /* Transfered session (ie afp_socket) to old disconnected child, now kill the new one */
            LOG(log_note, logtype_afpd,
                "Reconnect: killing new session child[%u] after transfer",
                ipc.child_pid);
            kill(ipc.child_pid, SIGTERM);
        }

        close(ipc.afp_socket);
        break;

    case IPC_GETSESSION:
        if (ipc_get_session(&ipc, children) != 0) {
            return -1;
        }

        break;

    case IPC_STATE:
        if (ipc_set_state(&ipc, children) != 0) {
            return -1;
        }

        break;

    case IPC_VOLUMES:
        if (ipc_set_volumes(&ipc, children) != 0) {
            return -1;
        }

        break;

    case IPC_LOGINDONE:
        if (ipc_login_done(&ipc, children) != 0) {
            return -1;
        }

        break;

    default:
        LOG(log_info, logtype_afpd, "ipc_read: unknown command: %d", ipc.command);
        return -1;
    }

    return 0;
}

/* ----------------- */
int ipc_child_write(int fd, uint16_t command, int len, void *msg)
{
    char block[IPC_MAXMSGSIZE], *p;
    pid_t pid;
    uid_t uid;
    ssize_t ret;
    p = block;
    memset(p, 0, IPC_MAXMSGSIZE);

    if (len + IPC_HEADERLEN > IPC_MAXMSGSIZE) {
        return -1;
    }

    memcpy(p, &command, sizeof(command));
    p   += sizeof(command);
    pid = getpid();
    memcpy(p, &pid, sizeof(pid_t));
    p += sizeof(pid_t);
    /* FIXME
     * using uid is wrong. It will not disconnect if the new connection
     * is with a different user.
     * But we really don't want a remote kill command.
    */
    uid = geteuid();
    memcpy(p, &uid, sizeof(uid_t));
    p += sizeof(uid_t);
    memcpy(p, &len, 4);
    p += 4;
    memcpy(p, msg, len);
    LOG(log_debug, logtype_afpd, "ipc_child_write(%s)", ipc_cmd_str[command]);

    if ((ret = writet(fd, block, len + IPC_HEADERLEN, 0,
                      1)) != len + IPC_HEADERLEN) {
        return -1;
    }

    return 0;
}

int ipc_child_state(AFPObj *obj, uint16_t state)
{
    return ipc_child_write(obj->ipc_fd, IPC_STATE, sizeof(uint16_t), &state);
}
