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

#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include "mconsole.h"

static struct mconsole_command commands[] = {
        /*
         * With uts namespaces, uts information becomes process-specific, so
         * we need a process context.  If we try handling this in interrupt
         * context, we may hit an exiting process without a valid uts
         * namespace.
         */
        { "version", mconsole_version, MCONSOLE_PROC },
        { "halt", mconsole_halt, MCONSOLE_PROC },
        { "reboot", mconsole_reboot, MCONSOLE_PROC },
        { "config", mconsole_config, MCONSOLE_PROC },
        { "remove", mconsole_remove, MCONSOLE_PROC },
        { "sysrq", mconsole_sysrq, MCONSOLE_INTR },
        { "help", mconsole_help, MCONSOLE_INTR },
        { "cad", mconsole_cad, MCONSOLE_INTR },
        { "stop", mconsole_stop, MCONSOLE_PROC },
        { "go", mconsole_go, MCONSOLE_INTR },
        { "log", mconsole_log, MCONSOLE_INTR },
        { "proc", mconsole_proc, MCONSOLE_PROC },
        { "stack", mconsole_stack, MCONSOLE_INTR },
};

/* Initialized in mconsole_init, which is an initcall */
char mconsole_socket_name[256];

static int mconsole_reply_v0(struct mc_request *req, char *reply)
{
        struct iovec iov;
        struct msghdr msg;

        iov.iov_base = reply;
        iov.iov_len = strlen(reply);

        msg.msg_name = &(req->origin);
        msg.msg_namelen = req->originlen;
        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;
        msg.msg_control = NULL;
        msg.msg_controllen = 0;
        msg.msg_flags = 0;

        return sendmsg(req->originating_fd, &msg, 0);
}

static struct mconsole_command *mconsole_parse(struct mc_request *req)
{
        struct mconsole_command *cmd;
        int i;

        for (i = 0; i < ARRAY_SIZE(commands); i++) {
                cmd = &commands[i];
                if (!strncmp(req->request.data, cmd->command,
                            strlen(cmd->command))) {
                        return cmd;
                }
        }
        return NULL;
}

#ifndef MIN
#define MIN(a,b) ((a)<(b) ? (a):(b))
#endif

#define STRINGX(x) #x
#define STRING(x) STRINGX(x)

int mconsole_get_request(int fd, struct mc_request *req)
{
        int len;

        req->originlen = sizeof(req->origin);
        req->len = recvfrom(fd, &req->request, sizeof(req->request), 0,
                            (struct sockaddr *) req->origin, &req->originlen);
        if (req->len < 0)
                return 0;

        req->originating_fd = fd;

        if (req->request.magic != MCONSOLE_MAGIC) {
                /* Unversioned request */
                len = MIN(sizeof(req->request.data) - 1,
                          strlen((char *) &req->request));
                memmove(req->request.data, &req->request, len);
                req->request.data[len] = '\0';

                req->request.magic = MCONSOLE_MAGIC;
                req->request.version = 0;
                req->request.len = len;

                mconsole_reply_v0(req, "ERR Version 0 mconsole clients are "
                                  "not supported by this driver");
                return 0;
        }

        if (req->request.len >= MCONSOLE_MAX_DATA) {
                mconsole_reply(req, "Request too large", 1, 0);
                return 0;
        }
        if (req->request.version != MCONSOLE_VERSION) {
                mconsole_reply(req, "This driver only supports version "
                               STRING(MCONSOLE_VERSION) " clients", 1, 0);
        }

        req->request.data[req->request.len] = '\0';
        req->cmd = mconsole_parse(req);
        if (req->cmd == NULL) {
                mconsole_reply(req, "Unknown command", 1, 0);
                return 0;
        }

        return 1;
}

int mconsole_reply_len(struct mc_request *req, const char *str, int total,
                       int err, int more)
{
        /*
         * XXX This is a stack consumption problem.  It'd be nice to
         * make it global and serialize access to it, but there are a
         * ton of callers to this function.
         */
        struct mconsole_reply reply;
        int len, n;

        do {
                reply.err = err;

                /* err can only be true on the first packet */
                err = 0;

                len = MIN(total, MCONSOLE_MAX_DATA - 1);

                if (len == total) reply.more = more;
                else reply.more = 1;

                memcpy(reply.data, str, len);
                reply.data[len] = '\0';
                total -= len;
                str += len;
                reply.len = len + 1;

                len = sizeof(reply) + reply.len - sizeof(reply.data);

                n = sendto(req->originating_fd, &reply, len, 0,
                           (struct sockaddr *) req->origin, req->originlen);

                if (n < 0)
                        return -errno;
        } while (total > 0);
        return 0;
}

int mconsole_reply(struct mc_request *req, const char *str, int err, int more)
{
        return mconsole_reply_len(req, str, strlen(str), err, more);
}


int mconsole_unlink_socket(void)
{
        unlink(mconsole_socket_name);
        return 0;
}

static int notify_sock = -1;

int mconsole_notify(char *sock_name, int type, const void *data, int len)
{
        struct sockaddr_un target;
        struct mconsole_notify packet;
        int n, err = 0;

        lock_notify();
        if (notify_sock < 0) {
                notify_sock = socket(PF_UNIX, SOCK_DGRAM, 0);
                if (notify_sock < 0) {
                        err = -errno;
                        printk(UM_KERN_ERR "mconsole_notify - socket failed, "
                               "errno = %d\n", errno);
                }
        }
        unlock_notify();

        if (err)
                return err;

        target.sun_family = AF_UNIX;
        strcpy(target.sun_path, sock_name);

        packet.magic = MCONSOLE_MAGIC;
        packet.version = MCONSOLE_VERSION;
        packet.type = type;
        len = (len > sizeof(packet.data)) ? sizeof(packet.data) : len;
        packet.len = len;
        memcpy(packet.data, data, len);

        err = 0;
        len = sizeof(packet) + packet.len - sizeof(packet.data);
        n = sendto(notify_sock, &packet, len, 0, (struct sockaddr *) &target,
                   sizeof(target));
        if (n < 0) {
                err = -errno;
                printk(UM_KERN_ERR "mconsole_notify - sendto failed, "
                       "errno = %d\n", errno);
        }
        return err;
}