[systemd-devel] [PATCH 05/28] dhcp: Add option appending and parsing
Zbigniew Jędrzejewski-Szmek
zbyszek at in.waw.pl
Wed Nov 13 15:52:01 PST 2013
On Wed, Nov 13, 2013 at 11:22:33PM +0200, Patrik Flykt wrote:
> Add functions to append and parse DHCP options. Not all options
> are passed to the callback function, the ones not exposed are
> pad, end, message type and overload. If indicated by the overload
> option, file and sname fields will be examined for more options.
>
> The option functions are internal to DHCP, add a new header files
> for interal function prototypes.
> ---
> src/dhcp/internal.h | 34 ++++++++++
> src/dhcp/option.c | 181 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 215 insertions(+)
> create mode 100644 src/dhcp/internal.h
> create mode 100644 src/dhcp/option.c
>
> diff --git a/src/dhcp/internal.h b/src/dhcp/internal.h
> new file mode 100644
> index 0000000..65a3bb3
> --- /dev/null
> +++ b/src/dhcp/internal.h
> @@ -0,0 +1,34 @@
> +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
> +
> +#pragma once
> +
> +/***
> + This file is part of systemd.
> +
> + Copyright (C) 2013 Intel Corporation. All rights reserved.
> +
> + systemd is free software; you can redistribute it and/or modify it
> + under the terms of the GNU Lesser General Public License as published by
> + the Free Software Foundation; either version 2.1 of the License, or
> + (at your option) any later version.
> +
> + systemd is distributed in the hope that it will be useful, but
> + WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public License
> + along with systemd; If not, see <http://www.gnu.org/licenses/>.
> +***/
> +
> +#include <stdint.h>
> +
> +#include "protocol.h"
> +
> +int __dhcp_option_append(uint8_t **buf, int *buflen, uint8_t code,
> + uint8_t optlen, void *optval);
> +
> +typedef int (*dhcp_option_cb_t)(uint8_t code, uint8_t len, uint8_t *option,
> + void *user_data);
> +int __dhcp_option_parse(DHCPMessage *message, int32_t len,
> + dhcp_option_cb_t cb, void *user_data);
Why "__"?
> diff --git a/src/dhcp/option.c b/src/dhcp/option.c
> new file mode 100644
> index 0000000..f5ca6e7
> --- /dev/null
> +++ b/src/dhcp/option.c
> @@ -0,0 +1,181 @@
> +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
> +
> +/***
> + This file is part of systemd.
> +
> + Copyright (C) 2013 Intel Corporation. All rights reserved.
> +
> + systemd is free software; you can redistribute it and/or modify it
> + under the terms of the GNU Lesser General Public License as published by
> + the Free Software Foundation; either version 2.1 of the License, or
> + (at your option) any later version.
> +
> + systemd is distributed in the hope that it will be useful, but
> + WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public License
> + along with systemd; If not, see <http://www.gnu.org/licenses/>.
> +***/
> +
> +#include <stdint.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <stdio.h>
> +
> +#include "internal.h"
> +
> +int __dhcp_option_append(uint8_t **buf, int *buflen, uint8_t code,
> + uint8_t optlen, void *optval)
> +{
> + if (!buf || !buflen)
> + return -EINVAL;
> +
> + switch (code) {
> +
> + case DHCP_OPTION_PAD:
> + case DHCP_OPTION_END:
> + if (*buflen < 1)
> + return -ENOBUFS;
> +
> + (*buf)[0] = code;
> + *buf += 1;
> + *buflen -= 1;
> + break;
> +
> + default:
> + if (*buflen < optlen + 2)
> + return -ENOBUFS;
> +
> + if (!optval)
> + return -EINVAL;
> +
> + (*buf)[0] = code;
> + (*buf)[1] = optlen;
> + memcpy(&(*buf)[2], optval, optlen);
> +
> + *buf += optlen + 2;
> + *buflen = *buflen - optlen - 2;
> +
> + break;
> + }
> +
> + return 0;
> +}
> +
> +static int parse_options(uint8_t *buf, int32_t buflen, int *overload,
> + int *message_type, dhcp_option_cb_t cb,
> + void *user_data)
> +{
> + uint8_t *code = buf;
> + uint8_t *len;
> +
> + while (buflen > 0) {
> + switch (*code) {
> + case DHCP_OPTION_PAD:
> + buflen -= 1;
> + code++;
> + break;
> +
> + case DHCP_OPTION_END:
> + return 0;
> +
> + case DHCP_OPTION_MESSAGE_TYPE:
> + buflen -= 3;
> + if (buflen < 0)
> + return -ENOBUFS;
> +
> + len = code + 1;
> + if (*len != 1)
> + return -EINVAL;
> +
> + if (message_type)
> + *message_type = *(len + 1);
> +
> + code = code + 3;
> +
> + break;
> +
> + case DHCP_OPTION_OVERLOAD:
> + buflen -= 3;
> + if (buflen < 0)
> + return -ENOBUFS;
> +
> + len = code + 1;
> + if (*len != 1)
> + return -EINVAL;
> +
> + if (overload)
> + *overload = *(len + 1);
> +
> + code = code + 3;
code += 3; ?
> +
> + break;
> +
> + default:
> + if (buflen < 3)
> + return -ENOBUFS;
> +
> + len = code + 1;
> + buflen -= *len + 2;
> +
> + if (buflen < 0)
> + return -EINVAL;
> +
> + if (cb)
> + cb(*code, *len, len + 1, user_data);
> +
> + code = code + *len + 2;
code += *len + 2; ?
> +
> + break;
> + }
> + }
> +
> + if (buflen)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +int __dhcp_option_parse(DHCPMessage *message, int32_t len,
> + dhcp_option_cb_t cb, void *user_data)
> +{
> + int overload = 0;
> + int message_type = -ENOMSG;
> + uint8_t *opt = (uint8_t *)(message + 1);
> + int res;
> +
> + if (message == NULL || len < 0)
> + return -EINVAL;
> +
> + len -= sizeof(DHCPMessage);
> + len -= 4;
> + if (len < 0)
> + return -EINVAL;
> +
> + if (opt[0] != 0x63 && opt[1] != 0x82 && opt[2] != 0x53 &&
> + opt[3] != 0x63)
> + return -EINVAL;
> +
> + res = parse_options(&opt[4], len, &overload, &message_type,
> + cb, user_data);
> + if (res < 0)
> + return res;
> +
> + if (overload & DHCP_OVERLOAD_FILE) {
> + res = parse_options(message->file, sizeof(message->file),
> + NULL, &message_type, cb, user_data);
> + if (res < 0)
> + return res;
> + }
> +
> + if (overload & DHCP_OVERLOAD_SNAME) {
> + res = parse_options(message->sname, sizeof(message->sname),
> + NULL, &message_type, cb, user_data);
> + if (res < 0)
> + return res;
> + }
> +
> + return message_type;
> +}
Zbyszek
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