dhcpmsg.c revision 4f6e8d7a00cbeda1e70cc15be9c4af1018bdad53 
1/*
2 * Copyright 2008, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdio.h>
18#include <stdarg.h>
19#include <string.h>
20#include <netinet/in.h>
21
22#include "dhcpmsg.h"
23
24static void *init_dhcp_msg(dhcp_msg *msg, int type, void *hwaddr, uint32_t xid)
25{
26    uint8_t *x;
27
28    memset(msg, 0, sizeof(dhcp_msg));
29
30    msg->op = OP_BOOTREQUEST;
31    msg->htype = HTYPE_ETHER;
32    msg->hlen = 6;
33    msg->hops = 0;
34
35    msg->flags = htons(FLAGS_BROADCAST);
36
37    msg->xid = xid;
38
39    memcpy(msg->chaddr, hwaddr, 6);
40
41    x = msg->options;
42
43    *x++ = OPT_COOKIE1;
44    *x++ = OPT_COOKIE2;
45    *x++ = OPT_COOKIE3;
46    *x++ = OPT_COOKIE4;
47
48    *x++ = OPT_MESSAGE_TYPE;
49    *x++ = 1;
50    *x++ = type;
51
52    return x;
53}
54
55int init_dhcp_discover_msg(dhcp_msg *msg, void *hwaddr, uint32_t xid)
56{
57    uint8_t *x;
58
59    x = init_dhcp_msg(msg, DHCPDISCOVER, hwaddr, xid);
60
61    *x++ = OPT_PARAMETER_LIST;
62    *x++ = 4;
63    *x++ = OPT_SUBNET_MASK;
64    *x++ = OPT_GATEWAY;
65    *x++ = OPT_DNS;
66    *x++ = OPT_BROADCAST_ADDR;
67
68    *x++ = OPT_END;
69
70    return DHCP_MSG_FIXED_SIZE + (x - msg->options);
71}
72
73int init_dhcp_request_msg(dhcp_msg *msg, void *hwaddr, uint32_t xid,
74                          uint32_t ipaddr, uint32_t serveraddr)
75{
76    uint8_t *x;
77
78    x = init_dhcp_msg(msg, DHCPREQUEST, hwaddr, xid);
79
80    *x++ = OPT_PARAMETER_LIST;
81    *x++ = 4;
82    *x++ = OPT_SUBNET_MASK;
83    *x++ = OPT_GATEWAY;
84    *x++ = OPT_DNS;
85    *x++ = OPT_BROADCAST_ADDR;
86
87    *x++ = OPT_REQUESTED_IP;
88    *x++ = 4;
89    memcpy(x, &ipaddr, 4);
90    x +=  4;
91
92    *x++ = OPT_SERVER_ID;
93    *x++ = 4;
94    memcpy(x, &serveraddr, 4);
95    x += 4;
96
97    *x++ = OPT_END;
98
99    return DHCP_MSG_FIXED_SIZE + (x - msg->options);
100}
101