src/slirp/bootp.c

/*
 * QEMU BOOTP/DHCP server
 * 
 * Copyright (c) 2004 Fabrice Bellard
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#include <slirp.h>

/* XXX: only DHCP is supported */

#define NB_ADDR 16

#define START_ADDR 15

#define LEASE_TIME (24 * 3600)

typedef struct {
    uint8_t allocated;
    uint8_t macaddr[6];
} BOOTPClient;

BOOTPClient bootp_clients[NB_ADDR];

static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };

static BOOTPClient *get_new_addr(struct in_addr *paddr)
{
    BOOTPClient *bc;
    int i;

    for(i = 0; i < NB_ADDR; i++) {
        if (!bootp_clients[i].allocated)
            goto found;
    }
    return NULL;
 found:
    bc = &bootp_clients[i];
    bc->allocated = 1;
    paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
    return bc;
}

static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)
{
    BOOTPClient *bc;
    int i;

    for(i = 0; i < NB_ADDR; i++) {
        if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
            goto found;
    }
    return NULL;
 found:
    bc = &bootp_clients[i];
    bc->allocated = 1;
    paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
    return bc;
}

static void dhcp_decode(const uint8_t *buf, int size,
                        int *pmsg_type)
{
    const uint8_t *p, *p_end;
    int len, tag;

    *pmsg_type = 0;    

    p = buf;
    p_end = buf + size;
    if (size < 5)
        return;
    if (memcmp(p, rfc1533_cookie, 4) != 0)
        return;
    p += 4;
    while (p < p_end) {
        tag = p[0];
        if (tag == RFC1533_PAD) {
            p++; 
        } else if (tag == RFC1533_END) {
            break;
        } else {
            p++;
            if (p >= p_end)
                break;
            len = *p++;

            switch(tag) {
            case RFC2132_MSG_TYPE:
                if (len >= 1)
                    *pmsg_type = p[0];
                break;
            default:
                break;
            }
            p += len;
        }
    }
}

static void bootp_reply(struct bootp_t *bp)
{
    BOOTPClient *bc;
    struct mbuf *m;
    struct bootp_t *rbp;
    struct sockaddr_in saddr, daddr;
    struct in_addr dns_addr;
    int dhcp_msg_type, val;
    uint8_t *q;

    /* extract exact DHCP msg type */
    dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type);
    
    if (dhcp_msg_type == 0)
        dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
        
    if (dhcp_msg_type != DHCPDISCOVER && 
        dhcp_msg_type != DHCPREQUEST)
        return;
    /* XXX: this is a hack to get the client mac address */
    memcpy(client_ethaddr, bp->bp_hwaddr, 6);
    
    if ((m = m_get()) == NULL)
        return;
    m->m_data += if_maxlinkhdr;
    rbp = (struct bootp_t *)m->m_data;
    m->m_data += sizeof(struct udpiphdr);
    memset(rbp, 0, sizeof(struct bootp_t));

    if (dhcp_msg_type == DHCPDISCOVER) {
    new_addr:
        bc = get_new_addr(&daddr.sin_addr);
        if (!bc)
            return;
        memcpy(bc->macaddr, client_ethaddr, 6);
    } else {
        bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
        if (!bc) {
            /* if never assigned, behaves as if it was already
               assigned (windows fix because it remembers its address) */
            goto new_addr;
        }
    }

    saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);
    saddr.sin_port = htons(BOOTP_SERVER);

    daddr.sin_port = htons(BOOTP_CLIENT);

    rbp->bp_op = BOOTP_REPLY;
    rbp->bp_xid = bp->bp_xid;
    rbp->bp_htype = 1;
    rbp->bp_hlen = 6;
    memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);

    rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
    rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */

    q = rbp->bp_vend;
    memcpy(q, rfc1533_cookie, 4);
    q += 4;

    if (dhcp_msg_type == DHCPDISCOVER) {
        *q++ = RFC2132_MSG_TYPE;
        *q++ = 1;
        *q++ = DHCPOFFER;
    } else if (dhcp_msg_type == DHCPREQUEST) {
        *q++ = RFC2132_MSG_TYPE;
        *q++ = 1;
        *q++ = DHCPACK;
    }
        
    if (dhcp_msg_type == DHCPDISCOVER ||
        dhcp_msg_type == DHCPREQUEST) {
        *q++ = RFC2132_SRV_ID;
        *q++ = 4;
        memcpy(q, &saddr.sin_addr, 4);
        q += 4;

        *q++ = RFC1533_NETMASK;
        *q++ = 4;
        *q++ = 0xff;
        *q++ = 0xff;
        *q++ = 0xff;
        *q++ = 0x00;
        
        *q++ = RFC1533_GATEWAY;
        *q++ = 4;
        memcpy(q, &saddr.sin_addr, 4);
        q += 4;
        
        *q++ = RFC1533_DNS;
        *q++ = 4;
        dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
        memcpy(q, &dns_addr, 4);
        q += 4;

        *q++ = RFC2132_LEASE_TIME;
        *q++ = 4;
        val = htonl(LEASE_TIME);
        memcpy(q, &val, 4);
        q += 4;

        if (*slirp_hostname) {
            val = strlen(slirp_hostname);
            *q++ = RFC1533_HOSTNAME;
            *q++ = val;
            memcpy(q, slirp_hostname, val);
            q += val;
        }
    }
    *q++ = RFC1533_END;
    
    m->m_len = sizeof(struct bootp_t) - 
        sizeof(struct ip) - sizeof(struct udphdr);
    udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
}

void bootp_input(struct mbuf *m)
{
    struct bootp_t *bp = mtod(m, struct bootp_t *);

    if (bp->bp_op == BOOTP_REQUEST) {
        bootp_reply(bp);
    }
}
Revision:	1.4
Committed:	2007-11-03T11:11:42Z (16 years, 6 months ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.3:	+8 -0 lines
Log Message:	Update to slirp sources from QEMU 0.8.2: - set slirp client hostname - fix slirp redirection on systems without a useful host IP address - separate alias_addr (10.0.2.2) from our_addr (Ed Swierk) - fix 32+ KB packets handling (Ed Swierk) - fix UDP broadcast translation error - solaris port (Ben Taylor)
#	Content
1	/*
2	* QEMU BOOTP/DHCP server
3	*
4	* Copyright (c) 2004 Fabrice Bellard
5	*
6	* Permission is hereby granted, free of charge, to any person obtaining a copy
7	* of this software and associated documentation files (the "Software"), to deal
8	* in the Software without restriction, including without limitation the rights
9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10	* copies of the Software, and to permit persons to whom the Software is
11	* furnished to do so, subject to the following conditions:
12	*
13	* The above copyright notice and this permission notice shall be included in
14	* all copies or substantial portions of the Software.
15	*
16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22	* THE SOFTWARE.
23	*/
24	#include <slirp.h>
25
26	/* XXX: only DHCP is supported */
27
28	#define NB_ADDR 16
29
30	#define START_ADDR 15
31
32	#define LEASE_TIME (24 * 3600)
33
34	typedef struct {
35	uint8_t allocated;
36	uint8_t macaddr[6];
37	} BOOTPClient;
38
39	BOOTPClient bootp_clients[NB_ADDR];
40
41	static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
42
43	static BOOTPClient get_new_addr(struct in_addr paddr)
44	{
45	BOOTPClient *bc;
46	int i;
47
48	for(i = 0; i < NB_ADDR; i++) {
49	if (!bootp_clients[i].allocated)
50	goto found;
51	}
52	return NULL;
53	found:
54	bc = &bootp_clients[i];
55	bc->allocated = 1;
56	paddr->s_addr = htonl(ntohl(special_addr.s_addr) \| (i + START_ADDR));
57	return bc;
58	}
59
60	static BOOTPClient find_addr(struct in_addr paddr, const uint8_t *macaddr)
61	{
62	BOOTPClient *bc;
63	int i;
64
65	for(i = 0; i < NB_ADDR; i++) {
66	if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
67	goto found;
68	}
69	return NULL;
70	found:
71	bc = &bootp_clients[i];
72	bc->allocated = 1;
73	paddr->s_addr = htonl(ntohl(special_addr.s_addr) \| (i + START_ADDR));
74	return bc;
75	}
76
77	static void dhcp_decode(const uint8_t *buf, int size,
78	int *pmsg_type)
79	{
80	const uint8_t p, p_end;
81	int len, tag;
82
83	*pmsg_type = 0;
84
85	p = buf;
86	p_end = buf + size;
87	if (size < 5)
88	return;
89	if (memcmp(p, rfc1533_cookie, 4) != 0)
90	return;
91	p += 4;
92	while (p < p_end) {
93	tag = p[0];
94	if (tag == RFC1533_PAD) {
95	p++;
96	} else if (tag == RFC1533_END) {
97	break;
98	} else {
99	p++;
100	if (p >= p_end)
101	break;
102	len = *p++;
103
104	switch(tag) {
105	case RFC2132_MSG_TYPE:
106	if (len >= 1)
107	*pmsg_type = p[0];
108	break;
109	default:
110	break;
111	}
112	p += len;
113	}
114	}
115	}
116
117	static void bootp_reply(struct bootp_t *bp)
118	{
119	BOOTPClient *bc;
120	struct mbuf *m;
121	struct bootp_t *rbp;
122	struct sockaddr_in saddr, daddr;
123	struct in_addr dns_addr;
124	int dhcp_msg_type, val;
125	uint8_t *q;
126
127	/* extract exact DHCP msg type */
128	dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type);
129
130	if (dhcp_msg_type == 0)
131	dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
132
133	if (dhcp_msg_type != DHCPDISCOVER &&
134	dhcp_msg_type != DHCPREQUEST)
135	return;
136	/* XXX: this is a hack to get the client mac address */
137	memcpy(client_ethaddr, bp->bp_hwaddr, 6);
138
139	if ((m = m_get()) == NULL)
140	return;
141	m->m_data += if_maxlinkhdr;
142	rbp = (struct bootp_t *)m->m_data;
143	m->m_data += sizeof(struct udpiphdr);
144	memset(rbp, 0, sizeof(struct bootp_t));
145
146	if (dhcp_msg_type == DHCPDISCOVER) {
147	new_addr:
148	bc = get_new_addr(&daddr.sin_addr);
149	if (!bc)
150	return;
151	memcpy(bc->macaddr, client_ethaddr, 6);
152	} else {
153	bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
154	if (!bc) {
155	/* if never assigned, behaves as if it was already
156	assigned (windows fix because it remembers its address) */
157	goto new_addr;
158	}
159	}
160
161	saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) \| CTL_ALIAS);
162	saddr.sin_port = htons(BOOTP_SERVER);
163
164	daddr.sin_port = htons(BOOTP_CLIENT);
165
166	rbp->bp_op = BOOTP_REPLY;
167	rbp->bp_xid = bp->bp_xid;
168	rbp->bp_htype = 1;
169	rbp->bp_hlen = 6;
170	memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
171
172	rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
173	rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
174
175	q = rbp->bp_vend;
176	memcpy(q, rfc1533_cookie, 4);
177	q += 4;
178
179	if (dhcp_msg_type == DHCPDISCOVER) {
180	*q++ = RFC2132_MSG_TYPE;
181	*q++ = 1;
182	*q++ = DHCPOFFER;
183	} else if (dhcp_msg_type == DHCPREQUEST) {
184	*q++ = RFC2132_MSG_TYPE;
185	*q++ = 1;
186	*q++ = DHCPACK;
187	}
188
189	if (dhcp_msg_type == DHCPDISCOVER \|\|
190	dhcp_msg_type == DHCPREQUEST) {
191	*q++ = RFC2132_SRV_ID;
192	*q++ = 4;
193	memcpy(q, &saddr.sin_addr, 4);
194	q += 4;
195
196	*q++ = RFC1533_NETMASK;
197	*q++ = 4;
198	*q++ = 0xff;
199	*q++ = 0xff;
200	*q++ = 0xff;
201	*q++ = 0x00;
202
203	*q++ = RFC1533_GATEWAY;
204	*q++ = 4;
205	memcpy(q, &saddr.sin_addr, 4);
206	q += 4;
207
208	*q++ = RFC1533_DNS;
209	*q++ = 4;
210	dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) \| CTL_DNS);
211	memcpy(q, &dns_addr, 4);
212	q += 4;
213
214	*q++ = RFC2132_LEASE_TIME;
215	*q++ = 4;
216	val = htonl(LEASE_TIME);
217	memcpy(q, &val, 4);
218	q += 4;
219
220	if (*slirp_hostname) {
221	val = strlen(slirp_hostname);
222	*q++ = RFC1533_HOSTNAME;
223	*q++ = val;
224	memcpy(q, slirp_hostname, val);
225	q += val;
226	}
227	}
228	*q++ = RFC1533_END;
229
230	m->m_len = sizeof(struct bootp_t) -
231	sizeof(struct ip) - sizeof(struct udphdr);
232	udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
233	}
234
235	void bootp_input(struct mbuf *m)
236	{
237	struct bootp_t bp = mtod(m, struct bootp_t );
238
239	if (bp->bp_op == BOOTP_REQUEST) {
240	bootp_reply(bp);
241	}
242	}