source: MondoRescue/branches/stable/mindi-busybox/networking/dnsd.c @ 1770

Last change on this file since 1770 was 1770, checked in by Bruno Cornec, 12 years ago
  • Better output for mindi-busybox revision
  • Remove dummy file created on NFS - report from Arnaud Tiger <arnaud.tiger_at_hp.com>
  • strace useful for debug
  • fix new versions for pb (2.0.0 for mindi and 1.7.2 for mindi-busybox)
  • fix build process for mindi-busybox + options used in that version (dd for label-partitions-as-necessary)
  • fix typo in label-partitions-as-necessary which doesn't seem to work
  • Update to busybox 1.7.2
  • perl is now required at restore time to support uuid swap partitions (and will be used for many other thigs

in the future for sure)

  • next mindi version will be 2.0.0 due to all the changes made in it (udev may break working distros)
  • small optimization in mindi on keyboard handling (one single find instead of multiple)
  • better interaction for USB device when launching mindi manually
  • attempt to automatically guess block disk size for ramdisk
  • fix typos in bkphw
  • Fix the remaining problem with UUID support for swap partitions
  • Updates mondoarchive man page for USB support
  • Adds preliminary Hardware support to mindi (Proliant SSSTK)
  • Tries to add udev support also for rhel4
  • Fix UUID support which was still broken.
  • Be conservative in test for the start-nfs script
  • Update config file for mindi-busybox for 1.7.2 migration
  • Try to run around a busybox bug (1.2.2 pb on inexistant links)
  • Add build content for mindi-busybox in pb
  • Remove distributions content for mindi-busybox
  • Fix a warning on inexistant raidtab
  • Solve problem on tmpfs in restore init (Problem of inexistant symlink and busybox)
  • Create MONDO_CACHE and use it everywhere + creation at start
  • Really never try to eject a USB device
  • Fix a issue with &> usage (replaced with 1> and 2>)
  • Adds magic file to depllist in order to have file working + ldd which helps for debugging issues
  • tty modes correct to avoid sh error messages
  • Use ext3 normally and not ext2 instead
  • USB device should be corrected after reading (take 1st part)
  • Adds a mount_USB_here function derived from mount_CDROM_here
  • usb detection place before /dev detection in device name at restore time
  • Fix when restoring from USB: media is asked in interactive mode
  • Adds USB support for mondorestore
  • mount_cdrom => mount_media
  • elilo.efi is now searched throughout /boot/efi and not in a fixed place as there is no standard
  • untar-and-softlink => untar (+ interface change)
  • suppress useless softlinks creation/removal in boot process
  • avoids udevd messages on groups
  • Increase # of disks to 99 as in mindi at restore time (should be a conf file parameter)
  • skip existing big file creation
  • seems to work correctly for USB mindi boot
  • Adds group and tty link to udev conf
  • Always load usb-torage (even 2.6) to initiate USB bus discovery
  • Better printing of messages
  • Attempt to fix a bug in supporting OpenSusE 10.3 kernel for initramfs (mindi may now use multiple regex for kernel initrd detection)
  • Links were not correctly done as non relative for modules in mindi
  • exclusion of modules denied now works
  • Also create modules in their ordinary place, so that classical modprobe works + copy modules.dep
  • Fix bugs for DENY_MODS handling
  • Add device /dev/console for udev
  • ide-generic should now really be excluded
  • Fix a bug in major number for tty
  • If udev then adds modprobe/insmod to rootfs
  • tty0 is also cretaed with udev
  • ide-generic put rather in DENY_MODS
  • udevd remove from deplist s handled in mindi directly
  • better default for mindi when using --usb
  • Handles dynamically linked busybox (in case we want to use it soon ;-)
  • Adds fixed devices to create for udev
  • ide-generic should not be part of the initrd when using libata v2
  • support a dynamically linked udev (case on Ubuntu 7.10 and Mandriva 2008.0 so should be quite generic) This will give incitation to move to dyn. linked binaries in the initrd which will help for other tasks (ia6 4)
  • Improvement in udev support (do not use cl options not available in busybox)
  • Udev in mindi
    • auto creation of the right links at boot time with udev-links.conf(from Mandriva 2008.0)
    • rework startup of udev as current makes kernel crash (from Mandriva 2008.0)
    • add support for 64 bits udev
  • Try to render MyInsmod? silent at boot time
  • Adds udev support (mandatory for newest distributions to avoid remapping of devices in a different way as on the original system)
  • We also need vaft format support for USB boot
  • Adds libusual support (Ubuntu 7.10 needs it for USB)
  • Improve Ubuntu/Debian? keyboard detection and support
  • pbinit adapted to new pb (0.8.10). Filtering of docs done in it
  • Suppress some mondo warnings and errors on USB again
  • Tries to fix lack of files in deb mindi package
  • Verify should now work for USB devices
  • More log/mesages improvement for USB support
  • - Supress g_erase_tmpdir_and_scratchdir
  • Improve some log messages for USB support
  • Try to improve install in mindi to avoid issues with isolinux.cfg not installed vene if in the pkg :-(
  • Improve mindi-busybox build
  • In conformity with pb 0.8.9
  • Add support for Ubuntu 7.10 in build process
  • Add USB Key button to Menu UI (CD streamer removed)
  • Attempt to fix error messages on tmp/scratch files at the end by removing those dir at the latest possible.
  • Fix a bug linked to the size of the -E param which could be used (Arnaud Tiger/René? Ribaud).
  • Integrate ~/.pbrc content into mondorescue.pb (required project-builder >= 0.8.7)
  • Put mondorescue in conformity with new pb filtering rules
  • Add USB support at restore time (no test done yet). New start-usb script PB varibale added where useful
  • Unmounting USB device before removal of temporary scratchdir
  • Stil refining USB copy back to mondo (one command was not executed)
  • No need to have the image subdor in the csratchdir when USB.
  • umount the USB partition before attempting to use it
  • Remove useless copy from mindi to mondo at end of USB handling

(risky merge, we are raising the limits of 2 diverging branches. The status of stable is not completely sure as such. Will need lots of tests, but it's not yet done :-()
(merge -r1692:1769 $SVN_M/branches/2.2.5)

File size: 9.6 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * Mini DNS server implementation for busybox
4 *
5 * Copyright (C) 2005 Roberto A. Foglietta (me@roberto.foglietta.name)
6 * Copyright (C) 2005 Odd Arild Olsen (oao at fibula dot no)
7 * Copyright (C) 2003 Paul Sheer
8 *
9 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
10 *
11 * Odd Arild Olsen started out with the sheerdns [1] of Paul Sheer and rewrote
12 * it into a shape which I believe is both easier to understand and maintain.
13 * I also reused the input buffer for output and removed services he did not
14 * need.  [1] http://threading.2038bug.com/sheerdns/
15 *
16 * Some bugfix and minor changes was applied by Roberto A. Foglietta who made
17 * the first porting of oao' scdns to busybox also.
18 */
19
20#include <syslog.h>
21#include "libbb.h"
22
23//#define DEBUG 1
24#define DEBUG 0
25
26enum {
27    MAX_HOST_LEN = 16,      // longest host name allowed is 15
28    IP_STRING_LEN = 18,     // .xxx.xxx.xxx.xxx\0
29
30//must be strlen('.in-addr.arpa') larger than IP_STRING_LEN
31    MAX_NAME_LEN = (IP_STRING_LEN + 13),
32
33/* Cannot get bigger packets than 512 per RFC1035
34   In practice this can be set considerably smaller:
35   Length of response packet is  header (12B) + 2*type(4B) + 2*class(4B) +
36   ttl(4B) + rlen(2B) + r (MAX_NAME_LEN =21B) +
37   2*querystring (2 MAX_NAME_LEN= 42B), all together 90 Byte
38*/
39    MAX_PACK_LEN = 512 + 1,
40
41    DEFAULT_TTL = 30,       // increase this when not testing?
42
43    REQ_A = 1,
44    REQ_PTR = 12
45};
46
47struct dns_repl {       // resource record, add 0 or 1 to accepted dns_msg in resp
48    uint16_t rlen;
49    uint8_t *r;     // resource
50    uint16_t flags;
51};
52
53struct dns_head {       // the message from client and first part of response mag
54    uint16_t id;
55    uint16_t flags;
56    uint16_t nquer;     // accepts 0
57    uint16_t nansw;     // 1 in response
58    uint16_t nauth;     // 0
59    uint16_t nadd;      // 0
60};
61struct dns_prop {
62    uint16_t type;
63    uint16_t class;
64};
65struct dns_entry {      // element of known name, ip address and reversed ip address
66    struct dns_entry *next;
67    char ip[IP_STRING_LEN];     // dotted decimal IP
68    char rip[IP_STRING_LEN];    // length decimal reversed IP
69    char name[MAX_HOST_LEN];
70};
71
72static struct dns_entry *dnsentry;
73static uint32_t ttl = DEFAULT_TTL;
74
75static const char *fileconf = "/etc/dnsd.conf";
76
77// Must match getopt32 call
78#define OPT_daemon  (option_mask32 & 0x10)
79#define OPT_verbose (option_mask32 & 0x20)
80
81
82/*
83 * Convert host name from C-string to dns length/string.
84 */
85static void convname(char *a, uint8_t *q)
86{
87    int i = (q[0] == '.') ? 0 : 1;
88    for (; i < MAX_HOST_LEN-1 && *q; i++, q++)
89        a[i] = tolower(*q);
90    a[0] = i - 1;
91    a[i] = 0;
92}
93
94/*
95 * Insert length of substrings instead of dots
96 */
97static void undot(uint8_t * rip)
98{
99    int i = 0, s = 0;
100    while (rip[i])
101        i++;
102    for (--i; i >= 0; i--) {
103        if (rip[i] == '.') {
104            rip[i] = s;
105            s = 0;
106        } else s++;
107    }
108}
109
110/*
111 * Read one line of hostname/IP from file
112 * Returns 0 for each valid entry read, -1 at EOF
113 * Assumes all host names are lower case only
114 * Hostnames with more than one label are not handled correctly.
115 * Presently the dot is copied into name without
116 * converting to a length/string substring for that label.
117 */
118static int getfileentry(FILE * fp, struct dns_entry *s)
119{
120    unsigned int a,b,c,d;
121    char *line, *r, *name;
122
123 restart:
124    line = r = xmalloc_fgets(fp);
125    if (!r)
126        return -1;
127    while (*r == ' ' || *r == '\t') {
128        r++;
129        if (!*r || *r == '#' || *r == '\n') {
130            free(line);
131            goto restart; /* skipping empty/blank and commented lines  */
132        }
133    }
134    name = r;
135    while (*r != ' ' && *r != '\t')
136        r++;
137    *r++ = '\0';
138    if (sscanf(r, ".%u.%u.%u.%u"+1, &a, &b, &c, &d) != 4) {
139        free(line);
140        goto restart; /* skipping wrong lines */
141    }
142
143    sprintf(s->ip, ".%u.%u.%u.%u"+1, a, b, c, d);
144    sprintf(s->rip, ".%u.%u.%u.%u", d, c, b, a);
145    undot((uint8_t*)s->rip);
146    convname(s->name, (uint8_t*)name);
147
148    if (OPT_verbose)
149        fprintf(stderr, "\tname:%s, ip:%s\n", &(s->name[1]),s->ip);
150
151    free(line);
152    return 0;
153}
154
155/*
156 * Read hostname/IP records from file
157 */
158static void dnsentryinit(void)
159{
160    FILE *fp;
161    struct dns_entry *m, *prev;
162
163    prev = dnsentry = NULL;
164    fp = xfopen(fileconf, "r");
165
166    while (1) {
167        m = xzalloc(sizeof(*m));
168        /*m->next = NULL;*/
169        if (getfileentry(fp, m))
170            break;
171
172        if (prev == NULL)
173            dnsentry = m;
174        else
175            prev->next = m;
176        prev = m;
177    }
178    fclose(fp);
179}
180
181/*
182 * Look query up in dns records and return answer if found
183 * qs is the query string, first byte the string length
184 */
185static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)
186{
187    int i;
188    struct dns_entry *d = dnsentry;
189
190    do {
191#if DEBUG
192        char *p,*q;
193        q = (char *)&(qs[1]);
194        p = &(d->name[1]);
195        fprintf(stderr, "\n%s: %d/%d p:%s q:%s %d",
196            __FUNCTION__, (int)strlen(p), (int)(d->name[0]),
197            p, q, (int)strlen(q));
198#endif
199        if (type == REQ_A) { /* search by host name */
200            for (i = 1; i <= (int)(d->name[0]); i++)
201                if (tolower(qs[i]) != d->name[i])
202                    break;
203            if (i > (int)(d->name[0])) {
204                strcpy((char *)as, d->ip);
205#if DEBUG
206                fprintf(stderr, " OK as:%s\n", as);
207#endif
208                return 0;
209            }
210        } else if (type == REQ_PTR) { /* search by IP-address */
211            if (!strncmp((char*)&d->rip[1], (char*)&qs[1], strlen(d->rip)-1)) {
212                strcpy((char *)as, d->name);
213                return 0;
214            }
215        }
216        d = d->next;
217    } while (d);
218    return -1;
219}
220
221
222/*
223 * Decode message and generate answer
224 */
225static int process_packet(uint8_t * buf)
226{
227    struct dns_head *head;
228    struct dns_prop *qprop;
229    struct dns_repl outr;
230    void *next, *from, *answb;
231
232    uint8_t answstr[MAX_NAME_LEN + 1];
233    int lookup_result, type, len, packet_len;
234    uint16_t flags;
235
236    answstr[0] = '\0';
237
238    head = (struct dns_head *)buf;
239    if (head->nquer == 0) {
240        bb_error_msg("no queries");
241        return -1;
242    }
243
244    if (head->flags & 0x8000) {
245        bb_error_msg("ignoring response packet");
246        return -1;
247    }
248
249    from = (void *)&head[1];    //  start of query string
250    next = answb = from + strlen((char *)from) + 1 + sizeof(struct dns_prop);   // where to append answer block
251
252    outr.rlen = 0;          // may change later
253    outr.r = NULL;
254    outr.flags = 0;
255
256    qprop = (struct dns_prop *)(answb - 4);
257    type = ntohs(qprop->type);
258
259    // only let REQ_A and REQ_PTR pass
260    if (!(type == REQ_A || type == REQ_PTR)) {
261        goto empty_packet;  /* we can't handle the query type */
262    }
263
264    if (ntohs(qprop->class) != 1 /* class INET */ ) {
265        outr.flags = 4; /* not supported */
266        goto empty_packet;
267    }
268    /* we only support standard queries */
269
270    if ((ntohs(head->flags) & 0x7800) != 0)
271        goto empty_packet;
272
273    // We have a standard query
274    bb_info_msg("%s", (char *)from);
275    lookup_result = table_lookup(type, answstr, (uint8_t*)from);
276    if (lookup_result != 0) {
277        outr.flags = 3 | 0x0400;    //name do not exist and auth
278        goto empty_packet;
279    }
280    if (type == REQ_A) {    // return an address
281        struct in_addr a;
282        if (!inet_aton((char*)answstr, &a)) {//dotted dec to long conv
283            outr.flags = 1; /* Frmt err */
284            goto empty_packet;
285        }
286        memcpy(answstr, &a.s_addr, 4);  // save before a disappears
287        outr.rlen = 4;          // uint32_t IP
288    } else
289        outr.rlen = strlen((char *)answstr) + 1;    // a host name
290    outr.r = answstr;           // 32 bit ip or a host name
291    outr.flags |= 0x0400;           /* authority-bit */
292    // we have an answer
293    head->nansw = htons(1);
294
295    // copy query block to answer block
296    len = answb - from;
297    memcpy(answb, from, len);
298    next += len;
299
300    // and append answer rr
301    *(uint32_t *) next = htonl(ttl);
302    next += 4;
303    *(uint16_t *) next = htons(outr.rlen);
304    next += 2;
305    memcpy(next, (void *)answstr, outr.rlen);
306    next += outr.rlen;
307
308 empty_packet:
309
310    flags = ntohs(head->flags);
311    // clear rcode and RA, set responsebit and our new flags
312    flags |= (outr.flags & 0xff80) | 0x8000;
313    head->flags = htons(flags);
314    head->nauth = head->nadd = htons(0);
315    head->nquer = htons(1);
316
317    packet_len = (uint8_t *)next - buf;
318    return packet_len;
319}
320
321/*
322 * Exit on signal
323 */
324static void interrupt(int x)
325{
326    /* unlink("/var/run/dnsd.lock"); */
327    bb_error_msg("interrupt, exiting\n");
328    exit(2);
329}
330
331int dnsd_main(int argc, char **argv);
332int dnsd_main(int argc, char **argv)
333{
334    const char *listen_interface = "0.0.0.0";
335    char *sttl, *sport;
336    len_and_sockaddr *lsa;
337    int udps;
338    uint16_t port = 53;
339    uint8_t buf[MAX_PACK_LEN];
340
341    getopt32(argv, "i:c:t:p:dv", &listen_interface, &fileconf, &sttl, &sport);
342    //if (option_mask32 & 0x1) // -i
343    //if (option_mask32 & 0x2) // -c
344    if (option_mask32 & 0x4) // -t
345        ttl = xatou_range(sttl, 1, 0xffffffff);
346    if (option_mask32 & 0x8) // -p
347        port = xatou_range(sport, 1, 0xffff);
348
349    if (OPT_verbose) {
350        bb_info_msg("listen_interface: %s", listen_interface);
351        bb_info_msg("ttl: %d, port: %d", ttl, port);
352        bb_info_msg("fileconf: %s", fileconf);
353    }
354
355    if (OPT_daemon) {
356        bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
357        openlog(applet_name, LOG_PID, LOG_DAEMON);
358        logmode = LOGMODE_SYSLOG;
359    }
360
361    dnsentryinit();
362
363    signal(SIGINT, interrupt);
364    /* why? signal(SIGPIPE, SIG_IGN); */
365    signal(SIGHUP, SIG_IGN);
366#ifdef SIGTSTP
367    signal(SIGTSTP, SIG_IGN);
368#endif
369#ifdef SIGURG
370    signal(SIGURG, SIG_IGN);
371#endif
372
373    lsa = xdotted2sockaddr(listen_interface, port);
374    udps = xsocket(lsa->sa.sa_family, SOCK_DGRAM, 0);
375    xbind(udps, &lsa->sa, lsa->len);
376    /* xlisten(udps, 50); - ?!! DGRAM sockets are never listened on I think? */
377    bb_info_msg("Accepting UDP packets on %s",
378            xmalloc_sockaddr2dotted(&lsa->sa));
379
380    while (1) {
381        int r;
382        socklen_t fromlen = lsa->len;
383// FIXME: need to get *DEST* address (to which of our addresses
384// this query was directed), and reply from the same address.
385// Or else we can exhibit usual UDP ugliness:
386// [ip1.multihomed.ip2] <=  query to ip1  <= peer
387// [ip1.multihomed.ip2] => reply from ip2 => peer (confused)
388        r = recvfrom(udps, buf, sizeof(buf), 0, &lsa->sa, &fromlen);
389        if (OPT_verbose)
390            bb_info_msg("Got UDP packet");
391        if (r < 12 || r > 512) {
392            bb_error_msg("invalid packet size");
393            continue;
394        }
395        r = process_packet(buf);
396        if (r <= 0)
397            continue;
398        sendto(udps, buf, r, 0, &lsa->sa, fromlen);
399    }
400    return 0;
401}
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