1/*	$NetBSD: bootp.c,v 1.14 1998/02/16 11:10:54 drochner Exp $	*/
2
3/*
4 * Copyright (c) 1992 Regents of the University of California.
5 * All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#) Header: bootp.c,v 1.4 93/09/11 03:13:51 leres Exp  (LBL)
36 */
37
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <sys/types.h>
42#include <netinet/in.h>
43#include <netinet/in_systm.h>
44
45#include <string.h>
46
47#define BOOTP_DEBUGxx
48#define SUPPORT_DHCP
49
50#define	DHCP_ENV_NOVENDOR	1	/* do not parse vendor options */
51#define	DHCP_ENV_PXE		10	/* assume pxe vendor options */
52#define	DHCP_ENV_FREEBSD	11	/* assume freebsd vendor options */
53/* set DHCP_ENV to one of the values above to export dhcp options to kenv */
54#define DHCP_ENV		DHCP_ENV_NO_VENDOR
55
56#include "stand.h"
57#include "net.h"
58#include "netif.h"
59#include "bootp.h"
60
61
62struct in_addr servip;
63
64static n_long	nmask, smask;
65
66static time_t	bot;
67
68static	char vm_rfc1048[4] = VM_RFC1048;
69#ifdef BOOTP_VEND_CMU
70static	char vm_cmu[4] = VM_CMU;
71#endif
72
73/* Local forwards */
74static	ssize_t bootpsend(struct iodesc *, void *, size_t);
75static	ssize_t bootprecv(struct iodesc *, void *, size_t, time_t);
76static	int vend_rfc1048(u_char *, u_int);
77#ifdef BOOTP_VEND_CMU
78static	void vend_cmu(u_char *);
79#endif
80
81#ifdef DHCP_ENV		/* export the dhcp response to kenv */
82struct dhcp_opt;
83static void setenv_(u_char *cp,  u_char *ep, struct dhcp_opt *opts);
84#else
85#define setenv_(a, b, c)
86#endif
87
88#ifdef SUPPORT_DHCP
89static char expected_dhcpmsgtype = -1, dhcp_ok;
90struct in_addr dhcp_serverip;
91#endif
92
93/* Fetch required bootp infomation */
94void
95bootp(sock, flag)
96	int sock;
97	int flag;
98{
99	struct iodesc *d;
100	struct bootp *bp;
101	struct {
102		u_char header[HEADER_SIZE];
103		struct bootp wbootp;
104	} wbuf;
105	struct {
106		u_char header[HEADER_SIZE];
107		struct bootp rbootp;
108	} rbuf;
109
110#ifdef BOOTP_DEBUG
111 	if (debug)
112		printf("bootp: socket=%d\n", sock);
113#endif
114	if (!bot)
115		bot = getsecs();
116
117	if (!(d = socktodesc(sock))) {
118		printf("bootp: bad socket. %d\n", sock);
119		return;
120	}
121#ifdef BOOTP_DEBUG
122 	if (debug)
123		printf("bootp: d=%lx\n", (long)d);
124#endif
125
126	bp = &wbuf.wbootp;
127	bzero(bp, sizeof(*bp));
128
129	bp->bp_op = BOOTREQUEST;
130	bp->bp_htype = 1;		/* 10Mb Ethernet (48 bits) */
131	bp->bp_hlen = 6;
132	bp->bp_xid = htonl(d->xid);
133	MACPY(d->myea, bp->bp_chaddr);
134	strncpy(bp->bp_file, bootfile, sizeof(bp->bp_file));
135	bcopy(vm_rfc1048, bp->bp_vend, sizeof(vm_rfc1048));
136#ifdef SUPPORT_DHCP
137	bp->bp_vend[4] = TAG_DHCP_MSGTYPE;
138	bp->bp_vend[5] = 1;
139	bp->bp_vend[6] = DHCPDISCOVER;
140
141	/*
142	 * If we are booting from PXE, we want to send the string
143	 * 'PXEClient' to the DHCP server so you have the option of
144	 * only responding to PXE aware dhcp requests.
145	 */
146	if (flag & BOOTP_PXE) {
147		bp->bp_vend[7] = TAG_CLASSID;
148		bp->bp_vend[8] = 9;
149		bcopy("PXEClient", &bp->bp_vend[9], 9);
150		bp->bp_vend[18] = TAG_END;
151	} else
152		bp->bp_vend[7] = TAG_END;
153#else
154	bp->bp_vend[4] = TAG_END;
155#endif
156
157	d->myip.s_addr = INADDR_ANY;
158	d->myport = htons(IPPORT_BOOTPC);
159	d->destip.s_addr = INADDR_BROADCAST;
160	d->destport = htons(IPPORT_BOOTPS);
161
162#ifdef SUPPORT_DHCP
163	expected_dhcpmsgtype = DHCPOFFER;
164	dhcp_ok = 0;
165#endif
166
167	if(sendrecv(d,
168		    bootpsend, bp, sizeof(*bp),
169		    bootprecv, &rbuf.rbootp, sizeof(rbuf.rbootp))
170	   == -1) {
171	    printf("bootp: no reply\n");
172	    return;
173	}
174
175#ifdef SUPPORT_DHCP
176	if(dhcp_ok) {
177		u_int32_t leasetime;
178		bp->bp_vend[6] = DHCPREQUEST;
179		bp->bp_vend[7] = TAG_REQ_ADDR;
180		bp->bp_vend[8] = 4;
181		bcopy(&rbuf.rbootp.bp_yiaddr, &bp->bp_vend[9], 4);
182		bp->bp_vend[13] = TAG_SERVERID;
183		bp->bp_vend[14] = 4;
184		bcopy(&dhcp_serverip.s_addr, &bp->bp_vend[15], 4);
185		bp->bp_vend[19] = TAG_LEASETIME;
186		bp->bp_vend[20] = 4;
187		leasetime = htonl(300);
188		bcopy(&leasetime, &bp->bp_vend[21], 4);
189		if (flag & BOOTP_PXE) {
190			bp->bp_vend[25] = TAG_CLASSID;
191			bp->bp_vend[26] = 9;
192			bcopy("PXEClient", &bp->bp_vend[27], 9);
193			bp->bp_vend[36] = TAG_END;
194		} else
195			bp->bp_vend[25] = TAG_END;
196
197		expected_dhcpmsgtype = DHCPACK;
198
199		if(sendrecv(d,
200			    bootpsend, bp, sizeof(*bp),
201			    bootprecv, &rbuf.rbootp, sizeof(rbuf.rbootp))
202		   == -1) {
203			printf("DHCPREQUEST failed\n");
204			return;
205		}
206	}
207#endif
208
209	myip = d->myip = rbuf.rbootp.bp_yiaddr;
210	servip = rbuf.rbootp.bp_siaddr;
211	if(rootip.s_addr == INADDR_ANY) rootip = servip;
212	bcopy(rbuf.rbootp.bp_file, bootfile, sizeof(bootfile));
213	bootfile[sizeof(bootfile) - 1] = '\0';
214
215	if (IN_CLASSA(ntohl(myip.s_addr)))
216		nmask = htonl(IN_CLASSA_NET);
217	else if (IN_CLASSB(ntohl(myip.s_addr)))
218		nmask = htonl(IN_CLASSB_NET);
219	else
220		nmask = htonl(IN_CLASSC_NET);
221#ifdef BOOTP_DEBUG
222	if (debug)
223		printf("'native netmask' is %s\n", intoa(nmask));
224#endif
225
226	/* Check subnet mask against net mask; toss if bogus */
227	if ((nmask & smask) != nmask) {
228#ifdef BOOTP_DEBUG
229		if (debug)
230			printf("subnet mask (%s) bad\n", intoa(smask));
231#endif
232		smask = 0;
233	}
234
235	/* Get subnet (or natural net) mask */
236	netmask = nmask;
237	if (smask)
238		netmask = smask;
239#ifdef BOOTP_DEBUG
240	if (debug)
241		printf("mask: %s\n", intoa(netmask));
242#endif
243
244	/* We need a gateway if root is on a different net */
245	if (!SAMENET(myip, rootip, netmask)) {
246#ifdef BOOTP_DEBUG
247		if (debug)
248			printf("need gateway for root ip\n");
249#endif
250	}
251
252	/* Toss gateway if on a different net */
253	if (!SAMENET(myip, gateip, netmask)) {
254#ifdef BOOTP_DEBUG
255		if (debug)
256			printf("gateway ip (%s) bad\n", inet_ntoa(gateip));
257#endif
258		gateip.s_addr = 0;
259	}
260
261	/* Bump xid so next request will be unique. */
262	++d->xid;
263}
264
265/* Transmit a bootp request */
266static ssize_t
267bootpsend(d, pkt, len)
268	struct iodesc *d;
269	void *pkt;
270	size_t len;
271{
272	struct bootp *bp;
273
274#ifdef BOOTP_DEBUG
275	if (debug)
276		printf("bootpsend: d=%lx called.\n", (long)d);
277#endif
278
279	bp = pkt;
280	bp->bp_secs = htons((u_short)(getsecs() - bot));
281
282#ifdef BOOTP_DEBUG
283	if (debug)
284		printf("bootpsend: calling sendudp\n");
285#endif
286
287	return (sendudp(d, pkt, len));
288}
289
290static ssize_t
291bootprecv(d, pkt, len, tleft)
292struct iodesc *d;
293void *pkt;
294size_t len;
295time_t tleft;
296{
297	ssize_t n;
298	struct bootp *bp;
299
300#ifdef BOOTP_DEBUGx
301	if (debug)
302		printf("bootp_recvoffer: called\n");
303#endif
304
305	n = readudp(d, pkt, len, tleft);
306	if (n == -1 || n < sizeof(struct bootp) - BOOTP_VENDSIZE)
307		goto bad;
308
309	bp = (struct bootp *)pkt;
310
311#ifdef BOOTP_DEBUG
312	if (debug)
313		printf("bootprecv: checked.  bp = 0x%lx, n = %d\n",
314		    (long)bp, (int)n);
315#endif
316	if (bp->bp_xid != htonl(d->xid)) {
317#ifdef BOOTP_DEBUG
318		if (debug) {
319			printf("bootprecv: expected xid 0x%lx, got 0x%x\n",
320			    d->xid, ntohl(bp->bp_xid));
321		}
322#endif
323		goto bad;
324	}
325
326#ifdef BOOTP_DEBUG
327	if (debug)
328		printf("bootprecv: got one!\n");
329#endif
330
331	/* Suck out vendor info */
332	if (bcmp(vm_rfc1048, bp->bp_vend, sizeof(vm_rfc1048)) == 0) {
333		if(vend_rfc1048(bp->bp_vend, sizeof(bp->bp_vend)) != 0)
334		    goto bad;
335	}
336#ifdef BOOTP_VEND_CMU
337	else if (bcmp(vm_cmu, bp->bp_vend, sizeof(vm_cmu)) == 0)
338		vend_cmu(bp->bp_vend);
339#endif
340	else
341		printf("bootprecv: unknown vendor 0x%lx\n", (long)bp->bp_vend);
342
343	return(n);
344bad:
345	errno = 0;
346	return (-1);
347}
348
349static int
350vend_rfc1048(cp, len)
351	u_char *cp;
352	u_int len;
353{
354	u_char *ep;
355	int size;
356	u_char tag;
357
358#ifdef BOOTP_DEBUG
359	if (debug)
360		printf("vend_rfc1048 bootp info. len=%d\n", len);
361#endif
362	ep = cp + len;
363
364	/* Step over magic cookie */
365	cp += sizeof(int);
366
367	setenv_(cp, ep, NULL);
368
369	while (cp < ep) {
370		tag = *cp++;
371		size = *cp++;
372		if (tag == TAG_END)
373			break;
374
375		if (tag == TAG_SUBNET_MASK) {
376			bcopy(cp, &smask, sizeof(smask));
377		}
378		if (tag == TAG_GATEWAY) {
379			bcopy(cp, &gateip.s_addr, sizeof(gateip.s_addr));
380		}
381		if (tag == TAG_SWAPSERVER) {
382			/* let it override bp_siaddr */
383			bcopy(cp, &rootip.s_addr, sizeof(swapip.s_addr));
384		}
385		if (tag == TAG_ROOTPATH) {
386			strncpy(rootpath, (char *)cp, sizeof(rootpath));
387			rootpath[size] = '\0';
388		}
389		if (tag == TAG_HOSTNAME) {
390			strncpy(hostname, (char *)cp, sizeof(hostname));
391			hostname[size] = '\0';
392		}
393#ifdef SUPPORT_DHCP
394		if (tag == TAG_DHCP_MSGTYPE) {
395			if(*cp != expected_dhcpmsgtype)
396			    return(-1);
397			dhcp_ok = 1;
398		}
399		if (tag == TAG_SERVERID) {
400			bcopy(cp, &dhcp_serverip.s_addr,
401			      sizeof(dhcp_serverip.s_addr));
402		}
403#endif
404		cp += size;
405	}
406	return(0);
407}
408
409#ifdef BOOTP_VEND_CMU
410static void
411vend_cmu(cp)
412	u_char *cp;
413{
414	struct cmu_vend *vp;
415
416#ifdef BOOTP_DEBUG
417	if (debug)
418		printf("vend_cmu bootp info.\n");
419#endif
420	vp = (struct cmu_vend *)cp;
421
422	if (vp->v_smask.s_addr != 0) {
423		smask = vp->v_smask.s_addr;
424	}
425	if (vp->v_dgate.s_addr != 0) {
426		gateip = vp->v_dgate;
427	}
428}
429#endif
430
431#ifdef DHCP_ENV
432/*
433 * Parse DHCP options and store them into kenv variables.
434 * Original code from Danny Braniss, modifications by Luigi Rizzo.
435 *
436 * The parser is driven by tables which specify the type and name of
437 * each dhcp option and how it appears in kenv.
438 * The first entry in the list contains the prefix used to set the kenv
439 * name (including the . if needed), the last entry must have a 0 tag.
440 * Entries do not need to be sorted though it helps for readability.
441 *
442 * Certain vendor-specific tables can be enabled according to DHCP_ENV.
443 * Set it to 0 if you don't want any.
444 */
445enum opt_fmt { __NONE = 0,
446	__8 = 1, __16 = 2, __32 = 4,	/* Unsigned fields, value=size	*/
447	__IP,				/* IPv4 address			*/
448	__TXT,				/* C string			*/
449	__BYTES,			/* byte sequence, printed %02x	*/
450	__INDIR,			/* name=value			*/
451	__ILIST,			/* name=value;name=value ... */
452	__VE,				/* vendor specific, recurse	*/
453};
454
455struct dhcp_opt {
456	uint8_t	tag;
457	uint8_t	fmt;
458	const char	*desc;
459};
460
461static struct dhcp_opt vndr_opt[] = { /* Vendor Specific Options */
462#if DHCP_ENV == DHCP_ENV_FREEBSD /* FreeBSD table in the original code */
463	{0,	0,	"FreeBSD"},		/* prefix */
464	{1,	__TXT,	"kernel"},
465	{2,	__TXT,	"kernelname"},
466	{3,	__TXT,	"kernel_options"},
467	{4,	__IP,	"usr-ip"},
468	{5,	__TXT,	"conf-path"},
469	{6,	__TXT,	"rc.conf0"},
470	{7,	__TXT,	"rc.conf1"},
471	{8,	__TXT,	"rc.conf2"},
472	{9,	__TXT,	"rc.conf3"},
473	{10,	__TXT,	"rc.conf4"},
474	{11,	__TXT,	"rc.conf5"},
475	{12,	__TXT,	"rc.conf6"},
476	{13,	__TXT,	"rc.conf7"},
477	{14,	__TXT,	"rc.conf8"},
478	{15,	__TXT,	"rc.conf9"},
479
480	{20,	__TXT,  "boot.nfsroot.options"},
481
482	{245,	__INDIR, ""},
483	{246,	__INDIR, ""},
484	{247,	__INDIR, ""},
485	{248,	__INDIR, ""},
486	{249,	__INDIR, ""},
487	{250,	__INDIR, ""},
488	{251,	__INDIR, ""},
489	{252,	__INDIR, ""},
490	{253,	__INDIR, ""},
491	{254,	__INDIR, ""},
492
493#elif DHCP_ENV == DHCP_ENV_PXE		/* some pxe options, RFC4578 */
494	{0,	0,	"pxe"},		/* prefix */
495	{93,	__16,	"system-architecture"},
496	{94,	__BYTES,	"network-interface"},
497	{97,	__BYTES,	"machine-identifier"},
498#else					/* default (empty) table */
499	{0,	0,	"dhcp.vendor."},		/* prefix */
500#endif
501	{0,	__TXT,	"%soption-%d"}
502};
503
504static struct dhcp_opt dhcp_opt[] = {
505	/* DHCP Option names, formats and codes, from RFC2132. */
506	{0,	0,	"dhcp."},	// prefix
507	{1,	__IP,	"subnet-mask"},
508	{2,	__32,	"time-offset"}, /* this is signed */
509	{3,	__IP,	"routers"},
510	{4,	__IP,	"time-servers"},
511	{5,	__IP,	"ien116-name-servers"},
512	{6,	__IP,	"domain-name-servers"},
513	{7,	__IP,	"log-servers"},
514	{8,	__IP,	"cookie-servers"},
515	{9,	__IP,	"lpr-servers"},
516	{10,	__IP,	"impress-servers"},
517	{11,	__IP,	"resource-location-servers"},
518	{12,	__TXT,	"host-name"},
519	{13,	__16,	"boot-size"},
520	{14,	__TXT,	"merit-dump"},
521	{15,	__TXT,	"domain-name"},
522	{16,	__IP,	"swap-server"},
523	{17,	__TXT,	"root-path"},
524	{18,	__TXT,	"extensions-path"},
525	{19,	__8,	"ip-forwarding"},
526	{20,	__8,	"non-local-source-routing"},
527	{21,	__IP,	"policy-filter"},
528	{22,	__16,	"max-dgram-reassembly"},
529	{23,	__8,	"default-ip-ttl"},
530	{24,	__32,	"path-mtu-aging-timeout"},
531	{25,	__16,	"path-mtu-plateau-table"},
532	{26,	__16,	"interface-mtu"},
533	{27,	__8,	"all-subnets-local"},
534	{28,	__IP,	"broadcast-address"},
535	{29,	__8,	"perform-mask-discovery"},
536	{30,	__8,	"mask-supplier"},
537	{31,	__8,	"perform-router-discovery"},
538	{32,	__IP,	"router-solicitation-address"},
539	{33,	__IP,	"static-routes"},
540	{34,	__8,	"trailer-encapsulation"},
541	{35,	__32,	"arp-cache-timeout"},
542	{36,	__8,	"ieee802-3-encapsulation"},
543	{37,	__8,	"default-tcp-ttl"},
544	{38,	__32,	"tcp-keepalive-interval"},
545	{39,	__8,	"tcp-keepalive-garbage"},
546	{40,	__TXT,	"nis-domain"},
547	{41,	__IP,	"nis-servers"},
548	{42,	__IP,	"ntp-servers"},
549	{43,	__VE,	"vendor-encapsulated-options"},
550	{44,	__IP,	"netbios-name-servers"},
551	{45,	__IP,	"netbios-dd-server"},
552	{46,	__8,	"netbios-node-type"},
553	{47,	__TXT,	"netbios-scope"},
554	{48,	__IP,	"x-font-servers"},
555	{49,	__IP,	"x-display-managers"},
556	{50,	__IP,	"dhcp-requested-address"},
557	{51,	__32,	"dhcp-lease-time"},
558	{52,	__8,	"dhcp-option-overload"},
559	{53,	__8,	"dhcp-message-type"},
560	{54,	__IP,	"dhcp-server-identifier"},
561	{55,	__8,	"dhcp-parameter-request-list"},
562	{56,	__TXT,	"dhcp-message"},
563	{57,	__16,	"dhcp-max-message-size"},
564	{58,	__32,	"dhcp-renewal-time"},
565	{59,	__32,	"dhcp-rebinding-time"},
566	{60,	__TXT,	"vendor-class-identifier"},
567	{61,	__TXT,	"dhcp-client-identifier"},
568	{64,	__TXT,	"nisplus-domain"},
569	{65,	__IP,	"nisplus-servers"},
570	{66,	__TXT,	"tftp-server-name"},
571	{67,	__TXT,	"bootfile-name"},
572	{68,	__IP,	"mobile-ip-home-agent"},
573	{69,	__IP,	"smtp-server"},
574	{70,	__IP,	"pop-server"},
575	{71,	__IP,	"nntp-server"},
576	{72,	__IP,	"www-server"},
577	{73,	__IP,	"finger-server"},
578	{74,	__IP,	"irc-server"},
579	{75,	__IP,	"streettalk-server"},
580	{76,	__IP,	"streettalk-directory-assistance-server"},
581	{77,	__TXT,	"user-class"},
582	{85,	__IP,	"nds-servers"},
583	{86,	__TXT,	"nds-tree-name"},
584	{87,	__TXT,	"nds-context"},
585	{210,	__TXT,	"authenticate"},
586
587	/* use the following entries for arbitrary variables */
588	{246,	__ILIST, ""},
589	{247,	__ILIST, ""},
590	{248,	__ILIST, ""},
591	{249,	__ILIST, ""},
592	{250,	__INDIR, ""},
593	{251,	__INDIR, ""},
594	{252,	__INDIR, ""},
595	{253,	__INDIR, ""},
596	{254,	__INDIR, ""},
597	{0,	__TXT,	"%soption-%d"}
598};
599
600/*
601 * parse a dhcp response, set environment variables translating options
602 * names and values according to the tables above. Also set dhcp.tags
603 * to the list of selected tags.
604 */
605static void
606setenv_(u_char *cp,  u_char *ep, struct dhcp_opt *opts)
607{
608    u_char	*ncp;
609    u_char	tag;
610    char	tags[512], *tp;	/* the list of tags */
611
612#define FLD_SEP	','	/* separator in list of elements */
613    ncp = cp;
614    tp = tags;
615    if (opts == NULL)
616	opts = dhcp_opt;
617
618    while (ncp < ep) {
619	unsigned int	size;		/* option size */
620	char *vp, *endv, buf[256];	/* the value buffer */
621	struct dhcp_opt *op;
622
623	tag = *ncp++;			/* extract tag and size */
624	size = *ncp++;
625	cp = ncp;			/* current payload */
626	ncp += size;			/* point to the next option */
627
628	if (tag == TAG_END)
629	    break;
630	if (tag == 0)
631	    continue;
632
633	for (op = opts+1; op->tag && op->tag != tag; op++)
634		;
635	/* if not found we end up on the default entry */
636
637	/*
638	 * Copy data into the buffer. libstand does not have snprintf so we
639	 * need to be careful with sprintf(). With strings, the source is
640	 * always <256 char so shorter than the buffer so we are safe; with
641	 * other arguments, the longest string is inet_ntoa which is 16 bytes
642	 * so we make sure to have always enough room in the string before
643	 * trying an sprint.
644	 */
645	vp = buf;
646	*vp = '\0';
647	endv = buf + sizeof(buf) - 1 - 16;	/* last valid write position */
648
649	switch(op->fmt) {
650	case __NONE:
651	    break;	/* should not happen */
652
653	case __VE: /* recurse, vendor specific */
654	    setenv_(cp, cp+size, vndr_opt);
655	    break;
656
657	case __IP:	/* ip address */
658	    for (; size > 0 && vp < endv; size -= 4, cp += 4) {
659		struct	in_addr in_ip;		/* ip addresses */
660		if (vp != buf)
661		    *vp++ = FLD_SEP;
662		bcopy(cp, &in_ip.s_addr, sizeof(in_ip.s_addr));
663		sprintf(vp, "%s", inet_ntoa(in_ip));
664		vp += strlen(vp);
665	    }
666	    break;
667
668	case __BYTES:	/* opaque byte string */
669	    for (; size > 0 && vp < endv; size -= 1, cp += 1) {
670		sprintf(vp, "%02x", *cp);
671		vp += strlen(vp);
672	    }
673	    break;
674
675	case __TXT:
676	    bcopy(cp, buf, size);	/* cannot overflow */
677	    buf[size] = 0;
678	    break;
679
680	case __32:
681	case __16:
682	case __8:	/* op->fmt is also the length of each field */
683	    for (; size > 0 && vp < endv; size -= op->fmt, cp += op->fmt) {
684		uint32_t v;
685		if (op->fmt == __32)
686			v = (cp[0]<<24) + (cp[1]<<16) + (cp[2]<<8) + cp[3];
687		else if (op->fmt == __16)
688			v = (cp[0]<<8) + cp[1];
689		else
690			v = cp[0];
691		if (vp != buf)
692		    *vp++ = FLD_SEP;
693		sprintf(vp, "%u", v);
694		vp += strlen(vp);
695	    }
696	    break;
697
698	case __INDIR:	/* name=value */
699	case __ILIST:	/* name=value;name=value... */
700	    bcopy(cp, buf, size);	/* cannot overflow */
701	    buf[size] = '\0';
702	    for (endv = buf; endv; endv = vp) {
703		u_char *s = NULL;	/* semicolon ? */
704
705		/* skip leading whitespace */
706		while (*endv && index(" \t\n\r", *endv))
707		    endv++;
708		vp = index(endv, '=');	/* find name=value separator */
709		if (!vp)
710		    break;
711		*vp++ = 0;
712		if (op->fmt == __ILIST && (s = index(vp, ';')))
713		    *s++ = '\0';
714		setenv(endv, vp, 1);
715		vp = s;	/* prepare for next round */
716	    }
717	    buf[0] = '\0';	/* option already done */
718	}
719
720	if (tp - tags < sizeof(tags) - 5) {	/* add tag to the list */
721	    if (tp != tags)
722		*tp++ = FLD_SEP;
723	    sprintf(tp, "%d", tag);
724	    tp += strlen(tp);
725	}
726	if (buf[0]) {
727	    char	env[128];	/* the string name */
728
729	    if (op->tag == 0)
730		sprintf(env, op->desc, opts[0].desc, tag);
731	    else
732		sprintf(env, "%s%s", opts[0].desc, op->desc);
733	    setenv(env, buf, 1);
734	}
735    }
736    if (tp != tags) {
737	char	env[128];	/* the string name */
738	sprintf(env, "%stags", opts[0].desc);
739	setenv(env, tags, 1);
740    }
741}
742#endif /* additional dhcp */
743