source: mainline/uspace/srv/net/dnsres/dns_msg.c@ 141a20d

/*
 * Copyright (c) 2012 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup dnsres
 * @{
 */
/**
 * @file
 */

#include <bitops.h>
#include <byteorder.h>
#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <str.h>

#include "dns_msg.h"
#include "dns_std.h"

#define NAME  "dnsres"

#include <stdio.h>
static int dns_name_encode(char *name, uint8_t *buf, size_t buf_size,
    size_t *act_size)
{
        size_t off;
        wchar_t c;
        size_t lsize;
        size_t pi, di;

        pi = 0;
        di = 1;
        off = 0;

        printf("dns_name_encode(name='%s', buf=%p, buf_size=%zu, act_size=%p\n",
            name, buf, buf_size, act_size);
        lsize = 0;
        while (true) {
                printf("off=%zu\n", off);
                c = str_decode(name, &off, STR_NO_LIMIT);
                printf("c=%d\n", (int)c);
                if (c > 127) {
                        /* Non-ASCII character */
                        printf("non-ascii character\n");
                        return EINVAL;
                }

                if (c == '.' || c == '\0') {
                        /* Empty string, starting with period or two consecutive periods. */
                        if (lsize == 0) {
                                printf("empty token\n");
                                return EINVAL;
                        }

                        if (lsize > DNS_LABEL_MAX_SIZE) {
                                /* Label too long */
                                printf("label too long\n");
                                return EINVAL;
                        }

                        if (buf != NULL && pi < buf_size)
                                buf[pi] = (uint8_t)lsize;

                        lsize = 0;
                        pi = di;
                        ++di;

                        if (c == '\0')
                                break;
                } else {
                        if (buf != NULL && di < buf_size)
                                buf[di] = c;
                        ++di;
                        ++lsize;
                }
        }

        if (buf != NULL && pi < buf_size)
                buf[pi] = 0;

        *act_size = di;
        return EOK;
}

static void dns_uint16_t_encode(uint16_t w, uint8_t *buf, size_t buf_size)
{
        if (buf != NULL && buf_size >= 1)
                buf[0] = w >> 8;

        if (buf != NULL && buf_size >= 2)
                buf[1] = w & 0xff;
}

static int dns_question_encode(dns_question_t *question, uint8_t *buf,
    size_t buf_size, size_t *act_size)
{
        size_t name_size;
        size_t di;
        int rc;

        rc = dns_name_encode(question->qname, buf, buf_size, &name_size);
        if (rc != EOK)
                return rc;

        printf("name_size=%zu\n", name_size);

        *act_size = name_size + sizeof(uint16_t) + sizeof(uint16_t);
        printf("act_size=%zu\n", *act_size);
        if (buf == NULL)
                return EOK;

        di = name_size;

        dns_uint16_t_encode(question->qtype, buf + di, buf_size - di);
        di += sizeof(uint16_t);

        dns_uint16_t_encode(question->qclass, buf + di, buf_size - di);
        di += sizeof(uint16_t);

        return EOK;
}

int dns_message_encode(dns_message_t *msg, void **rdata, size_t *rsize)
{
        uint8_t *data;
        size_t size;
        dns_header_t hdr;
        size_t q_size;
        size_t di;
        int rc;

        hdr.id = host2uint16_t_be(msg->id);

        hdr.opbits = host2uint16_t_be(
            (msg->qr << OPB_QR) |
            (msg->opcode << OPB_OPCODE_l) |
            (msg->aa ? BIT_V(uint16_t, OPB_AA) : 0) |
            (msg->tc ? BIT_V(uint16_t, OPB_TC) : 0) |
            (msg->rd ? BIT_V(uint16_t, OPB_RD) : 0) |
            (msg->ra ? BIT_V(uint16_t, OPB_RA) : 0) |
            msg->rcode
        );

        hdr.qd_count = host2uint16_t_be(list_count(&msg->question));
        hdr.an_count = 0;
        hdr.ns_count = 0;
        hdr.ar_count = 0;

        size = sizeof(dns_header_t);
        printf("dns header size=%zu\n", size);

        list_foreach(msg->question, link) {
                dns_question_t *q = list_get_instance(link, dns_question_t, msg);
                rc = dns_question_encode(q, NULL, 0, &q_size);
                if (rc != EOK)
                        return rc;

                printf("q_size=%zu\n", q_size);
                size += q_size;
        }

        data = calloc(1, size);
        if (data == NULL)
                return ENOMEM;

        memcpy(data, &hdr, sizeof(dns_header_t));
        di = sizeof(dns_header_t);

        list_foreach(msg->question, link) {
                dns_question_t *q = list_get_instance(link, dns_question_t, msg);
                rc = dns_question_encode(q, data + di, size - di, &q_size);
                assert(rc == EOK);

                di += q_size;
        }

        printf("-> size=%zu, di=%zu\n", size, di);
        *rdata = data;
        *rsize = size;
        return EOK;
}

/** @}
 */