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 };

#ifdef DEBUG
#define dprintf(fmt, args...) \
if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }
#else
#define dprintf(fmt, args...)
#endif

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++;
            dprintf("dhcp: tag=0x%02x len=%d\n", tag, len);

            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);
    dprintf("bootp packet op=%d msgtype=%d\n", bp->bp_op, 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) {
            dprintf("no address left\n");
            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;
        }
    }
    dprintf("offered addr=%08x\n", ntohl(daddr.sin_addr.s_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;
    }
    *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 = (struct bootp_t *)m->m_data;

    if (bp->bp_op == BOOTP_REQUEST) {
        bootp_reply(bp);
    }
}
Revision:	1.1
Committed:	2005-05-13T09:00:59Z (19 years, 1 month ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
Log Message:	slirp user mode network emulation code from qemu
#	User	Rev	Content
1	gbeauche	1.1	/*
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			#ifdef DEBUG
44			#define dprintf(fmt, args...) \
45			if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }
46			#else
47			#define dprintf(fmt, args...)
48			#endif
49
50			static BOOTPClient get_new_addr(struct in_addr paddr)
51			{
52			BOOTPClient *bc;
53			int i;
54
55			for(i = 0; i < NB_ADDR; i++) {
56			if (!bootp_clients[i].allocated)
57			goto found;
58			}
59			return NULL;
60			found:
61			bc = &bootp_clients[i];
62			bc->allocated = 1;
63			paddr->s_addr = htonl(ntohl(special_addr.s_addr) \| (i + START_ADDR));
64			return bc;
65			}
66
67			static BOOTPClient find_addr(struct in_addr paddr, const uint8_t *macaddr)
68			{
69			BOOTPClient *bc;
70			int i;
71
72			for(i = 0; i < NB_ADDR; i++) {
73			if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
74			goto found;
75			}
76			return NULL;
77			found:
78			bc = &bootp_clients[i];
79			bc->allocated = 1;
80			paddr->s_addr = htonl(ntohl(special_addr.s_addr) \| (i + START_ADDR));
81			return bc;
82			}
83
84			static void dhcp_decode(const uint8_t *buf, int size,
85			int *pmsg_type)
86			{
87			const uint8_t p, p_end;
88			int len, tag;
89
90			*pmsg_type = 0;
91
92			p = buf;
93			p_end = buf + size;
94			if (size < 5)
95			return;
96			if (memcmp(p, rfc1533_cookie, 4) != 0)
97			return;
98			p += 4;
99			while (p < p_end) {
100			tag = p[0];
101			if (tag == RFC1533_PAD) {
102			p++;
103			} else if (tag == RFC1533_END) {
104			break;
105			} else {
106			p++;
107			if (p >= p_end)
108			break;
109			len = *p++;
110			dprintf("dhcp: tag=0x%02x len=%d\n", tag, len);
111
112			switch(tag) {
113			case RFC2132_MSG_TYPE:
114			if (len >= 1)
115			*pmsg_type = p[0];
116			break;
117			default:
118			break;
119			}
120			p += len;
121			}
122			}
123			}
124
125			static void bootp_reply(struct bootp_t *bp)
126			{
127			BOOTPClient *bc;
128			struct mbuf *m;
129			struct bootp_t *rbp;
130			struct sockaddr_in saddr, daddr;
131			struct in_addr dns_addr;
132			int dhcp_msg_type, val;
133			uint8_t *q;
134
135			/* extract exact DHCP msg type */
136			dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type);
137			dprintf("bootp packet op=%d msgtype=%d\n", bp->bp_op, dhcp_msg_type);
138
139			if (dhcp_msg_type == 0)
140			dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
141
142			if (dhcp_msg_type != DHCPDISCOVER &&
143			dhcp_msg_type != DHCPREQUEST)
144			return;
145			/* XXX: this is a hack to get the client mac address */
146			memcpy(client_ethaddr, bp->bp_hwaddr, 6);
147
148			if ((m = m_get()) == NULL)
149			return;
150			m->m_data += if_maxlinkhdr;
151			rbp = (struct bootp_t *)m->m_data;
152			m->m_data += sizeof(struct udpiphdr);
153			memset(rbp, 0, sizeof(struct bootp_t));
154
155			if (dhcp_msg_type == DHCPDISCOVER) {
156			new_addr:
157			bc = get_new_addr(&daddr.sin_addr);
158			if (!bc) {
159			dprintf("no address left\n");
160			return;
161			}
162			memcpy(bc->macaddr, client_ethaddr, 6);
163			} else {
164			bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
165			if (!bc) {
166			/* if never assigned, behaves as if it was already
167			assigned (windows fix because it remembers its address) */
168			goto new_addr;
169			}
170			}
171			dprintf("offered addr=%08x\n", ntohl(daddr.sin_addr.s_addr));
172
173			saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) \| CTL_ALIAS);
174			saddr.sin_port = htons(BOOTP_SERVER);
175
176			daddr.sin_port = htons(BOOTP_CLIENT);
177
178			rbp->bp_op = BOOTP_REPLY;
179			rbp->bp_xid = bp->bp_xid;
180			rbp->bp_htype = 1;
181			rbp->bp_hlen = 6;
182			memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
183
184			rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
185			rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
186
187			q = rbp->bp_vend;
188			memcpy(q, rfc1533_cookie, 4);
189			q += 4;
190
191			if (dhcp_msg_type == DHCPDISCOVER) {
192			*q++ = RFC2132_MSG_TYPE;
193			*q++ = 1;
194			*q++ = DHCPOFFER;
195			} else if (dhcp_msg_type == DHCPREQUEST) {
196			*q++ = RFC2132_MSG_TYPE;
197			*q++ = 1;
198			*q++ = DHCPACK;
199			}
200
201			if (dhcp_msg_type == DHCPDISCOVER \|\|
202			dhcp_msg_type == DHCPREQUEST) {
203			*q++ = RFC2132_SRV_ID;
204			*q++ = 4;
205			memcpy(q, &saddr.sin_addr, 4);
206			q += 4;
207
208			*q++ = RFC1533_NETMASK;
209			*q++ = 4;
210			*q++ = 0xff;
211			*q++ = 0xff;
212			*q++ = 0xff;
213			*q++ = 0x00;
214
215			*q++ = RFC1533_GATEWAY;
216			*q++ = 4;
217			memcpy(q, &saddr.sin_addr, 4);
218			q += 4;
219
220			*q++ = RFC1533_DNS;
221			*q++ = 4;
222			dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) \| CTL_DNS);
223			memcpy(q, &dns_addr, 4);
224			q += 4;
225
226			*q++ = RFC2132_LEASE_TIME;
227			*q++ = 4;
228			val = htonl(LEASE_TIME);
229			memcpy(q, &val, 4);
230			q += 4;
231			}
232			*q++ = RFC1533_END;
233
234			m->m_len = sizeof(struct bootp_t) -
235			sizeof(struct ip) - sizeof(struct udphdr);
236			udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
237			}
238
239			void bootp_input(struct mbuf *m)
240			{
241			struct bootp_t bp = (struct bootp_t )m->m_data;
242
243			if (bp->bp_op == BOOTP_REQUEST) {
244			bootp_reply(bp);
245			}
246			}