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 * 3. 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
36 #include <stddef.h>
37 #include <sys/types.h>
38 #include <sys/limits.h>
39 #include <sys/endian.h>
40 #include <netinet/in.h>
41 #include <netinet/in_systm.h>
42
43 #include <string.h>
44
45 #define BOOTP_DEBUGxx
46 #define SUPPORT_DHCP
47
48 #define DHCP_ENV_NOVENDOR 1 /* do not parse vendor options */
49 #define DHCP_ENV_PXE 10 /* assume pxe vendor options */
50 #define DHCP_ENV_FREEBSD 11 /* assume freebsd vendor options */
51 /* set DHCP_ENV to one of the values above to export dhcp options to kenv */
52 #define DHCP_ENV DHCP_ENV_NO_VENDOR
53
54 #include "stand.h"
55 #include "net.h"
56 #include "netif.h"
57 #include "bootp.h"
58
59
60 struct in_addr servip;
61
62 static time_t bot;
63
64 static char vm_rfc1048[4] = VM_RFC1048;
65 #ifdef BOOTP_VEND_CMU
66 static char vm_cmu[4] = VM_CMU;
67 #endif
68
69 /* Local forwards */
70 static ssize_t bootpsend(struct iodesc *, void *, size_t);
71 static ssize_t bootprecv(struct iodesc *, void **, void **, time_t, void *);
72 static int vend_rfc1048(u_char *, u_int);
73 #ifdef BOOTP_VEND_CMU
74 static void vend_cmu(u_char *);
75 #endif
76
77 #ifdef DHCP_ENV /* export the dhcp response to kenv */
78 struct dhcp_opt;
79 static void setenv_(u_char *cp, u_char *ep, struct dhcp_opt *opts);
80 #else
81 #define setenv_(a, b, c)
82 #endif
83
84 #ifdef SUPPORT_DHCP
85 static char expected_dhcpmsgtype = -1, dhcp_ok;
86 struct in_addr dhcp_serverip;
87 #endif
88 struct bootp *bootp_response;
89 size_t bootp_response_size;
90
91 static void
bootp_fill_request(unsigned char * bp_vend)92 bootp_fill_request(unsigned char *bp_vend)
93 {
94 /*
95 * We are booting from PXE, we want to send the string
96 * 'PXEClient' to the DHCP server so you have the option of
97 * only responding to PXE aware dhcp requests.
98 */
99 bp_vend[0] = TAG_CLASSID;
100 bp_vend[1] = 9;
101 bcopy("PXEClient", &bp_vend[2], 9);
102 bp_vend[11] = TAG_USER_CLASS;
103 /* len of each user class + number of user class */
104 bp_vend[12] = 8;
105 /* len of the first user class */
106 bp_vend[13] = 7;
107 bcopy("FreeBSD", &bp_vend[14], 7);
108 bp_vend[21] = TAG_PARAM_REQ;
109 bp_vend[22] = 7;
110 bp_vend[23] = TAG_ROOTPATH;
111 bp_vend[24] = TAG_HOSTNAME;
112 bp_vend[25] = TAG_SWAPSERVER;
113 bp_vend[26] = TAG_GATEWAY;
114 bp_vend[27] = TAG_SUBNET_MASK;
115 bp_vend[28] = TAG_INTF_MTU;
116 bp_vend[29] = TAG_SERVERID;
117 bp_vend[30] = TAG_END;
118 }
119
120 /* Fetch required bootp infomation */
121 void
bootp(int sock)122 bootp(int sock)
123 {
124 void *pkt;
125 struct iodesc *d;
126 struct bootp *bp;
127 struct {
128 u_char header[HEADER_SIZE];
129 struct bootp wbootp;
130 } wbuf;
131 struct bootp *rbootp;
132
133 #ifdef BOOTP_DEBUG
134 if (debug)
135 printf("bootp: socket=%d\n", sock);
136 #endif
137 if (!bot)
138 bot = getsecs();
139
140 if (!(d = socktodesc(sock))) {
141 printf("bootp: bad socket. %d\n", sock);
142 return;
143 }
144 #ifdef BOOTP_DEBUG
145 if (debug)
146 printf("bootp: d=%lx\n", (long)d);
147 #endif
148
149 bp = &wbuf.wbootp;
150 bzero(bp, sizeof(*bp));
151
152 bp->bp_op = BOOTREQUEST;
153 bp->bp_htype = 1; /* 10Mb Ethernet (48 bits) */
154 bp->bp_hlen = 6;
155 bp->bp_xid = htonl(d->xid);
156 MACPY(d->myea, bp->bp_chaddr);
157 strncpy(bp->bp_file, bootfile, sizeof(bp->bp_file));
158 bcopy(vm_rfc1048, bp->bp_vend, sizeof(vm_rfc1048));
159 #ifdef SUPPORT_DHCP
160 bp->bp_vend[4] = TAG_DHCP_MSGTYPE;
161 bp->bp_vend[5] = 1;
162 bp->bp_vend[6] = DHCPDISCOVER;
163 bootp_fill_request(&bp->bp_vend[7]);
164
165 #else
166 bp->bp_vend[4] = TAG_END;
167 #endif
168
169 d->myip.s_addr = INADDR_ANY;
170 d->myport = htons(IPPORT_BOOTPC);
171 d->destip.s_addr = INADDR_BROADCAST;
172 d->destport = htons(IPPORT_BOOTPS);
173
174 #ifdef SUPPORT_DHCP
175 expected_dhcpmsgtype = DHCPOFFER;
176 dhcp_ok = 0;
177 #endif
178
179 if(sendrecv(d,
180 bootpsend, bp, sizeof(*bp),
181 bootprecv, &pkt, (void **)&rbootp, NULL) == -1) {
182 printf("bootp: no reply\n");
183 return;
184 }
185
186 #ifdef SUPPORT_DHCP
187 if(dhcp_ok) {
188 uint32_t leasetime;
189 bp->bp_vend[6] = DHCPREQUEST;
190 bp->bp_vend[7] = TAG_REQ_ADDR;
191 bp->bp_vend[8] = 4;
192 bcopy(&rbootp->bp_yiaddr, &bp->bp_vend[9], 4);
193 bp->bp_vend[13] = TAG_SERVERID;
194 bp->bp_vend[14] = 4;
195 bcopy(&dhcp_serverip.s_addr, &bp->bp_vend[15], 4);
196 bp->bp_vend[19] = TAG_LEASETIME;
197 bp->bp_vend[20] = 4;
198 leasetime = htonl(300);
199 bcopy(&leasetime, &bp->bp_vend[21], 4);
200 bootp_fill_request(&bp->bp_vend[25]);
201
202 expected_dhcpmsgtype = DHCPACK;
203
204 free(pkt);
205 if(sendrecv(d,
206 bootpsend, bp, sizeof(*bp),
207 bootprecv, &pkt, (void **)&rbootp, NULL) == -1) {
208 printf("DHCPREQUEST failed\n");
209 return;
210 }
211 }
212 #endif
213
214 myip = d->myip = rbootp->bp_yiaddr;
215 servip = rbootp->bp_siaddr;
216 if (rootip.s_addr == INADDR_ANY)
217 rootip = servip;
218 bcopy(rbootp->bp_file, bootfile, sizeof(bootfile));
219 bootfile[sizeof(bootfile) - 1] = '\0';
220
221 if (!netmask) {
222 if (IN_CLASSA(ntohl(myip.s_addr)))
223 netmask = htonl(IN_CLASSA_NET);
224 else if (IN_CLASSB(ntohl(myip.s_addr)))
225 netmask = htonl(IN_CLASSB_NET);
226 else
227 netmask = htonl(IN_CLASSC_NET);
228 #ifdef BOOTP_DEBUG
229 if (debug)
230 printf("'native netmask' is %s\n", intoa(netmask));
231 #endif
232 }
233
234 #ifdef BOOTP_DEBUG
235 if (debug)
236 printf("mask: %s\n", intoa(netmask));
237 #endif
238
239 /* We need a gateway if root is on a different net */
240 if (!SAMENET(myip, rootip, netmask)) {
241 #ifdef BOOTP_DEBUG
242 if (debug)
243 printf("need gateway for root ip\n");
244 #endif
245 }
246
247 /* Toss gateway if on a different net */
248 if (!SAMENET(myip, gateip, netmask)) {
249 #ifdef BOOTP_DEBUG
250 if (debug)
251 printf("gateway ip (%s) bad\n", inet_ntoa(gateip));
252 #endif
253 gateip.s_addr = 0;
254 }
255
256 /* Bump xid so next request will be unique. */
257 ++d->xid;
258 free(pkt);
259 }
260
261 /* Transmit a bootp request */
262 static ssize_t
bootpsend(struct iodesc * d,void * pkt,size_t len)263 bootpsend(struct iodesc *d, void *pkt, size_t len)
264 {
265 struct bootp *bp;
266
267 #ifdef BOOTP_DEBUG
268 if (debug)
269 printf("bootpsend: d=%lx called.\n", (long)d);
270 #endif
271
272 bp = pkt;
273 bp->bp_secs = htons((u_short)(getsecs() - bot));
274
275 #ifdef BOOTP_DEBUG
276 if (debug)
277 printf("bootpsend: calling sendudp\n");
278 #endif
279
280 return (sendudp(d, pkt, len));
281 }
282
283 static ssize_t
bootprecv(struct iodesc * d,void ** pkt,void ** payload,time_t tleft,void * extra)284 bootprecv(struct iodesc *d, void **pkt, void **payload, time_t tleft,
285 void *extra)
286 {
287 ssize_t n;
288 struct bootp *bp;
289 void *ptr;
290
291 #ifdef BOOTP_DEBUG
292 if (debug)
293 printf("bootp_recvoffer: called\n");
294 #endif
295
296 ptr = NULL;
297 n = readudp(d, &ptr, (void **)&bp, tleft);
298 if (n == -1 || n < sizeof(struct bootp) - BOOTP_VENDSIZE)
299 goto bad;
300
301 #ifdef BOOTP_DEBUG
302 if (debug)
303 printf("bootprecv: checked. bp = %p, n = %zd\n", bp, n);
304 #endif
305 if (bp->bp_xid != htonl(d->xid)) {
306 #ifdef BOOTP_DEBUG
307 if (debug) {
308 printf("bootprecv: expected xid 0x%lx, got 0x%x\n",
309 d->xid, ntohl(bp->bp_xid));
310 }
311 #endif
312 goto bad;
313 }
314
315 #ifdef BOOTP_DEBUG
316 if (debug)
317 printf("bootprecv: got one!\n");
318 #endif
319
320 /* Suck out vendor info */
321 if (bcmp(vm_rfc1048, bp->bp_vend, sizeof(vm_rfc1048)) == 0) {
322 int vsize = n - offsetof(struct bootp, bp_vend);
323 if (vend_rfc1048(bp->bp_vend, vsize) != 0)
324 goto bad;
325
326 /* Save copy of bootp reply or DHCP ACK message */
327 if (bp->bp_op == BOOTREPLY &&
328 ((dhcp_ok == 1 && expected_dhcpmsgtype == DHCPACK) ||
329 dhcp_ok == 0)) {
330 free(bootp_response);
331 bootp_response = malloc(n);
332 if (bootp_response != NULL) {
333 bootp_response_size = n;
334 bcopy(bp, bootp_response, bootp_response_size);
335 }
336 }
337 }
338 #ifdef BOOTP_VEND_CMU
339 else if (bcmp(vm_cmu, bp->bp_vend, sizeof(vm_cmu)) == 0)
340 vend_cmu(bp->bp_vend);
341 #endif
342 else
343 printf("bootprecv: unknown vendor 0x%lx\n", (long)bp->bp_vend);
344
345 *pkt = ptr;
346 *payload = bp;
347 return (n);
348 bad:
349 free(ptr);
350 errno = 0;
351 return (-1);
352 }
353
354 static int
vend_rfc1048(u_char * cp,u_int len)355 vend_rfc1048(u_char *cp, u_int len)
356 {
357 u_char *ep;
358 int size;
359 u_char tag;
360 const char *val;
361
362 #ifdef BOOTP_DEBUG
363 if (debug)
364 printf("vend_rfc1048 bootp info. len=%d\n", len);
365 #endif
366 ep = cp + len;
367
368 /* Step over magic cookie */
369 cp += sizeof(int);
370
371 setenv_(cp, ep, NULL);
372
373 while (cp < ep) {
374 tag = *cp++;
375 size = *cp++;
376 if (tag == TAG_END)
377 break;
378
379 if (tag == TAG_SUBNET_MASK) {
380 bcopy(cp, &netmask, sizeof(netmask));
381 }
382 if (tag == TAG_GATEWAY) {
383 bcopy(cp, &gateip.s_addr, sizeof(gateip.s_addr));
384 }
385 if (tag == TAG_SWAPSERVER) {
386 /* let it override bp_siaddr */
387 bcopy(cp, &rootip.s_addr, sizeof(rootip.s_addr));
388 }
389 if (tag == TAG_ROOTPATH) {
390 if ((val = getenv("dhcp.root-path")) == NULL)
391 val = (const char *)cp;
392 strlcpy(rootpath, val, sizeof(rootpath));
393 }
394 if (tag == TAG_HOSTNAME) {
395 if ((val = getenv("dhcp.host-name")) == NULL)
396 val = (const char *)cp;
397 strlcpy(hostname, val, sizeof(hostname));
398 }
399 if (tag == TAG_INTF_MTU) {
400 intf_mtu = 0;
401 if ((val = getenv("dhcp.interface-mtu")) != NULL) {
402 unsigned long tmp;
403 char *end;
404
405 errno = 0;
406 /*
407 * Do not allow MTU to exceed max IPv4 packet
408 * size, max value of 16-bit word.
409 */
410 tmp = strtoul(val, &end, 0);
411 if (errno != 0 ||
412 *val == '\0' || *end != '\0' ||
413 tmp > USHRT_MAX) {
414 printf("%s: bad value: \"%s\", "
415 "ignoring\n",
416 "dhcp.interface-mtu", val);
417 } else {
418 intf_mtu = (u_int)tmp;
419 }
420 }
421 if (intf_mtu <= 0)
422 intf_mtu = be16dec(cp);
423 }
424 #ifdef SUPPORT_DHCP
425 if (tag == TAG_DHCP_MSGTYPE) {
426 if(*cp != expected_dhcpmsgtype)
427 return(-1);
428 dhcp_ok = 1;
429 }
430 if (tag == TAG_SERVERID) {
431 bcopy(cp, &dhcp_serverip.s_addr,
432 sizeof(dhcp_serverip.s_addr));
433 }
434 #endif
435 cp += size;
436 }
437 return(0);
438 }
439
440 #ifdef BOOTP_VEND_CMU
441 static void
vend_cmu(u_char * cp)442 vend_cmu(u_char *cp)
443 {
444 struct cmu_vend *vp;
445
446 #ifdef BOOTP_DEBUG
447 if (debug)
448 printf("vend_cmu bootp info.\n");
449 #endif
450 vp = (struct cmu_vend *)cp;
451
452 if (vp->v_smask.s_addr != 0) {
453 netmask = vp->v_smask.s_addr;
454 }
455 if (vp->v_dgate.s_addr != 0) {
456 gateip = vp->v_dgate;
457 }
458 }
459 #endif
460
461 #ifdef DHCP_ENV
462 /*
463 * Parse DHCP options and store them into kenv variables.
464 * Original code from Danny Braniss, modifications by Luigi Rizzo.
465 *
466 * The parser is driven by tables which specify the type and name of
467 * each dhcp option and how it appears in kenv.
468 * The first entry in the list contains the prefix used to set the kenv
469 * name (including the . if needed), the last entry must have a 0 tag.
470 * Entries do not need to be sorted though it helps for readability.
471 *
472 * Certain vendor-specific tables can be enabled according to DHCP_ENV.
473 * Set it to 0 if you don't want any.
474 */
475 enum opt_fmt { __NONE = 0,
476 __8 = 1, __16 = 2, __32 = 4, /* Unsigned fields, value=size */
477 __IP, /* IPv4 address */
478 __TXT, /* C string */
479 __BYTES, /* byte sequence, printed %02x */
480 __INDIR, /* name=value */
481 __ILIST, /* name=value;name=value ... */
482 __VE, /* vendor specific, recurse */
483 };
484
485 struct dhcp_opt {
486 uint8_t tag;
487 uint8_t fmt;
488 const char *desc;
489 };
490
491 static struct dhcp_opt vndr_opt[] = { /* Vendor Specific Options */
492 #if DHCP_ENV == DHCP_ENV_FREEBSD /* FreeBSD table in the original code */
493 {0, 0, "FreeBSD"}, /* prefix */
494 {1, __TXT, "kernel"},
495 {2, __TXT, "kernelname"},
496 {3, __TXT, "kernel_options"},
497 {4, __IP, "usr-ip"},
498 {5, __TXT, "conf-path"},
499 {6, __TXT, "rc.conf0"},
500 {7, __TXT, "rc.conf1"},
501 {8, __TXT, "rc.conf2"},
502 {9, __TXT, "rc.conf3"},
503 {10, __TXT, "rc.conf4"},
504 {11, __TXT, "rc.conf5"},
505 {12, __TXT, "rc.conf6"},
506 {13, __TXT, "rc.conf7"},
507 {14, __TXT, "rc.conf8"},
508 {15, __TXT, "rc.conf9"},
509
510 {20, __TXT, "boot.nfsroot.options"},
511
512 {245, __INDIR, ""},
513 {246, __INDIR, ""},
514 {247, __INDIR, ""},
515 {248, __INDIR, ""},
516 {249, __INDIR, ""},
517 {250, __INDIR, ""},
518 {251, __INDIR, ""},
519 {252, __INDIR, ""},
520 {253, __INDIR, ""},
521 {254, __INDIR, ""},
522
523 #elif DHCP_ENV == DHCP_ENV_PXE /* some pxe options, RFC4578 */
524 {0, 0, "pxe"}, /* prefix */
525 {93, __16, "system-architecture"},
526 {94, __BYTES, "network-interface"},
527 {97, __BYTES, "machine-identifier"},
528 #else /* default (empty) table */
529 {0, 0, "dhcp.vendor."}, /* prefix */
530 #endif
531 {0, __TXT, "%soption-%d"}
532 };
533
534 static struct dhcp_opt dhcp_opt[] = {
535 /* DHCP Option names, formats and codes, from RFC2132. */
536 {0, 0, "dhcp."}, // prefix
537 {1, __IP, "subnet-mask"},
538 {2, __32, "time-offset"}, /* this is signed */
539 {3, __IP, "routers"},
540 {4, __IP, "time-servers"},
541 {5, __IP, "ien116-name-servers"},
542 {6, __IP, "domain-name-servers"},
543 {7, __IP, "log-servers"},
544 {8, __IP, "cookie-servers"},
545 {9, __IP, "lpr-servers"},
546 {10, __IP, "impress-servers"},
547 {11, __IP, "resource-location-servers"},
548 {12, __TXT, "host-name"},
549 {13, __16, "boot-size"},
550 {14, __TXT, "merit-dump"},
551 {15, __TXT, "domain-name"},
552 {16, __IP, "swap-server"},
553 {17, __TXT, "root-path"},
554 {18, __TXT, "extensions-path"},
555 {19, __8, "ip-forwarding"},
556 {20, __8, "non-local-source-routing"},
557 {21, __IP, "policy-filter"},
558 {22, __16, "max-dgram-reassembly"},
559 {23, __8, "default-ip-ttl"},
560 {24, __32, "path-mtu-aging-timeout"},
561 {25, __16, "path-mtu-plateau-table"},
562 {26, __16, "interface-mtu"},
563 {27, __8, "all-subnets-local"},
564 {28, __IP, "broadcast-address"},
565 {29, __8, "perform-mask-discovery"},
566 {30, __8, "mask-supplier"},
567 {31, __8, "perform-router-discovery"},
568 {32, __IP, "router-solicitation-address"},
569 {33, __IP, "static-routes"},
570 {34, __8, "trailer-encapsulation"},
571 {35, __32, "arp-cache-timeout"},
572 {36, __8, "ieee802-3-encapsulation"},
573 {37, __8, "default-tcp-ttl"},
574 {38, __32, "tcp-keepalive-interval"},
575 {39, __8, "tcp-keepalive-garbage"},
576 {40, __TXT, "nis-domain"},
577 {41, __IP, "nis-servers"},
578 {42, __IP, "ntp-servers"},
579 {43, __VE, "vendor-encapsulated-options"},
580 {44, __IP, "netbios-name-servers"},
581 {45, __IP, "netbios-dd-server"},
582 {46, __8, "netbios-node-type"},
583 {47, __TXT, "netbios-scope"},
584 {48, __IP, "x-font-servers"},
585 {49, __IP, "x-display-managers"},
586 {50, __IP, "dhcp-requested-address"},
587 {51, __32, "dhcp-lease-time"},
588 {52, __8, "dhcp-option-overload"},
589 {53, __8, "dhcp-message-type"},
590 {54, __IP, "dhcp-server-identifier"},
591 {55, __8, "dhcp-parameter-request-list"},
592 {56, __TXT, "dhcp-message"},
593 {57, __16, "dhcp-max-message-size"},
594 {58, __32, "dhcp-renewal-time"},
595 {59, __32, "dhcp-rebinding-time"},
596 {60, __TXT, "vendor-class-identifier"},
597 {61, __TXT, "dhcp-client-identifier"},
598 {64, __TXT, "nisplus-domain"},
599 {65, __IP, "nisplus-servers"},
600 {66, __TXT, "tftp-server-name"},
601 {67, __TXT, "bootfile-name"},
602 {68, __IP, "mobile-ip-home-agent"},
603 {69, __IP, "smtp-server"},
604 {70, __IP, "pop-server"},
605 {71, __IP, "nntp-server"},
606 {72, __IP, "www-server"},
607 {73, __IP, "finger-server"},
608 {74, __IP, "irc-server"},
609 {75, __IP, "streettalk-server"},
610 {76, __IP, "streettalk-directory-assistance-server"},
611 {77, __TXT, "user-class"},
612 {85, __IP, "nds-servers"},
613 {86, __TXT, "nds-tree-name"},
614 {87, __TXT, "nds-context"},
615 {210, __TXT, "authenticate"},
616
617 /* use the following entries for arbitrary variables */
618 {246, __ILIST, ""},
619 {247, __ILIST, ""},
620 {248, __ILIST, ""},
621 {249, __ILIST, ""},
622 {250, __INDIR, ""},
623 {251, __INDIR, ""},
624 {252, __INDIR, ""},
625 {253, __INDIR, ""},
626 {254, __INDIR, ""},
627 {0, __TXT, "%soption-%d"}
628 };
629
630 /*
631 * parse a dhcp response, set environment variables translating options
632 * names and values according to the tables above. Also set dhcp.tags
633 * to the list of selected tags.
634 */
635 static void
setenv_(u_char * cp,u_char * ep,struct dhcp_opt * opts)636 setenv_(u_char *cp, u_char *ep, struct dhcp_opt *opts)
637 {
638 u_char *ncp;
639 u_char tag;
640 char tags[512], *tp; /* the list of tags */
641
642 #define FLD_SEP ',' /* separator in list of elements */
643 ncp = cp;
644 tp = tags;
645 if (opts == NULL)
646 opts = dhcp_opt;
647
648 while (ncp < ep) {
649 unsigned int size; /* option size */
650 char *vp, *endv, buf[256]; /* the value buffer */
651 struct dhcp_opt *op;
652
653 tag = *ncp++; /* extract tag and size */
654 size = *ncp++;
655 cp = ncp; /* current payload */
656 ncp += size; /* point to the next option */
657
658 if (tag == TAG_END)
659 break;
660 if (tag == 0)
661 continue;
662
663 for (op = opts+1; op->tag && op->tag != tag; op++)
664 ;
665 /* if not found we end up on the default entry */
666
667 /*
668 * Copy data into the buffer. While the code uses snprintf, it's also
669 * careful never to insert strings that would be truncated. inet_ntoa is
670 * tricky to know the size, so it assumes we can always insert it
671 * because we reserve 16 bytes at the end of the string for its worst
672 * case. Other cases are covered because they will write fewer than
673 * these reserved bytes at the end. Source strings can't overflow (as
674 * noted below) because buf is 256 bytes and all strings are limited by
675 * the protocol to be 256 bytes or smaller.
676 */
677 vp = buf;
678 *vp = '\0';
679 endv = buf + sizeof(buf) - 1 - 16; /* last valid write position */
680
681 switch(op->fmt) {
682 case __NONE:
683 break; /* should not happen */
684
685 case __VE: /* recurse, vendor specific */
686 setenv_(cp, cp+size, vndr_opt);
687 break;
688
689 case __IP: /* ip address */
690 for (; size > 0 && vp < endv; size -= 4, cp += 4) {
691 struct in_addr in_ip; /* ip addresses */
692 if (vp != buf)
693 *vp++ = FLD_SEP;
694 bcopy(cp, &in_ip.s_addr, sizeof(in_ip.s_addr));
695 snprintf(vp, endv - vp, "%s", inet_ntoa(in_ip));
696 vp += strlen(vp);
697 }
698 break;
699
700 case __BYTES: /* opaque byte string */
701 for (; size > 0 && vp < endv; size -= 1, cp += 1) {
702 snprintf(vp, endv - vp, "%02x", *cp);
703 vp += strlen(vp);
704 }
705 break;
706
707 case __TXT:
708 bcopy(cp, buf, size); /* cannot overflow */
709 buf[size] = 0;
710 break;
711
712 case __32:
713 case __16:
714 case __8: /* op->fmt is also the length of each field */
715 for (; size > 0 && vp < endv; size -= op->fmt, cp += op->fmt) {
716 uint32_t v;
717 if (op->fmt == __32)
718 v = (cp[0]<<24) + (cp[1]<<16) + (cp[2]<<8) + cp[3];
719 else if (op->fmt == __16)
720 v = (cp[0]<<8) + cp[1];
721 else
722 v = cp[0];
723 if (vp != buf)
724 *vp++ = FLD_SEP;
725 snprintf(vp, endv - vp, "%u", v);
726 vp += strlen(vp);
727 }
728 break;
729
730 case __INDIR: /* name=value */
731 case __ILIST: /* name=value;name=value... */
732 bcopy(cp, buf, size); /* cannot overflow */
733 buf[size] = '\0';
734 for (endv = buf; endv; endv = vp) {
735 char *s = NULL; /* semicolon ? */
736
737 /* skip leading whitespace */
738 while (*endv && strchr(" \t\n\r", *endv))
739 endv++;
740 vp = strchr(endv, '='); /* find name=value separator */
741 if (!vp)
742 break;
743 *vp++ = 0;
744 if (op->fmt == __ILIST && (s = strchr(vp, ';')))
745 *s++ = '\0';
746 setenv(endv, vp, 1);
747 vp = s; /* prepare for next round */
748 }
749 buf[0] = '\0'; /* option already done */
750 break;
751 }
752
753 if (tp - tags < sizeof(tags) - 5) { /* add tag to the list */
754 if (tp != tags)
755 *tp++ = FLD_SEP;
756 snprintf(tp, sizeof(tags) - (tp - tags), "%d", tag);
757 tp += strlen(tp);
758 }
759 if (buf[0]) {
760 char env[128]; /* the string name */
761
762 if (op->tag == 0)
763 snprintf(env, sizeof(env), op->desc, opts[0].desc, tag);
764 else
765 snprintf(env, sizeof(env), "%s%s", opts[0].desc, op->desc);
766 /*
767 * Do not replace existing values in the environment, so that
768 * locally-obtained values can override server-provided values.
769 */
770 setenv(env, buf, 0);
771 }
772 }
773 if (tp != tags) {
774 char env[128]; /* the string name */
775 snprintf(env, sizeof(env), "%stags", opts[0].desc);
776 setenv(env, tags, 1);
777 }
778 }
779 #endif /* additional dhcp */
780