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new applet. Thanks Roberto A. Foglietta

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This commit is contained in:
"Vladimir N. Oleynik" 2006-01-25 14:19:11 +00:00
parent 8aa9e57149
commit 7b4aa6ffc6
7 changed files with 494 additions and 0 deletions
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3
AUTHORS
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@ -159,3 +159,6 @@ Tito Ragusa <farmatito@tiscali.it>
Paul Fox <pgf@foxharp.boston.ma.us>
vi editing mode for ash, various other patches/fixes
Roberto A. Foglietta <me@roberto.foglietta.name>
port: dnsd

1
examples/dnsd.conf Normal file
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@ -0,0 +1 @@
thebox 192.168.1.5

3
include/applets.h
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@ -164,6 +164,9 @@
#ifdef CONFIG_DMESG
APPLET(dmesg, dmesg_main, _BB_DIR_BIN, _BB_SUID_NEVER)
#endif
#ifdef CONFIG_DNSD
APPLET(dnsd, dnsd_main, _BB_DIR_USR_SBIN, _BB_SUID_ALWAYS)
#endif
#ifdef CONFIG_DOS2UNIX
APPLET(dos2unix, dos2unix_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
#endif

11
include/usage.h
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@ -469,6 +469,17 @@
"\t-n LEVEL\tSets console logging level\n" \
"\t-s SIZE\t\tUse a buffer of size SIZE"
#define dnsd_trivial_usage \
"[-c config] [-t seconds] [-p port] [-i iface-ip] [-d]"
#define dnsd_full_usage \
"Small and static DNS server daemon\n\n" \
"Options:\n" \
"\t-c\t\tconfig filename\n" \
"\t-t\t\tTTL in seconds\n" \
"\t-p\t\tlistening port\n" \
"\t-i\t\tlistening iface ip (default all)\n" \
"\t-d\t\tdaemonize"
#define dos2unix_trivial_usage \
"[option] [FILE]"
#define dos2unix_full_usage \

6
networking/Config.in
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@ -18,6 +18,12 @@ config CONFIG_ARPING
help
Ping hosts by ARP packets
config CONFIG_DNSD
bool "dnsd"
default n
help
Small and static DNS server deamon.
config CONFIG_ETHER_WAKE
bool "ether-wake"
default n

1
networking/Makefile.in
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@ -12,6 +12,7 @@ srcdir=$(top_srcdir)/networking
NETWORKING-y:=
NETWORKING-$(CONFIG_ARPING) += arping.o
NETWORKING-$(CONFIG_DNSD) += dnsd.o
NETWORKING-$(CONFIG_ETHER_WAKE) += ether-wake.o
NETWORKING-$(CONFIG_FAKEIDENTD) += fakeidentd.o
NETWORKING-$(CONFIG_FTPGET) += ftpgetput.o

469
networking/dnsd.c Normal file
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@ -0,0 +1,469 @@
/*
* Mini DNS server implementation for busybox
*
* Copyright (C) 2005 Roberto A. Foglietta (me@roberto.foglietta.name)
* Copyright (C) 2005 Odd Arild Olsen (oao at fibula dot no)
* Copyright (C) 2003 Paul Sheer
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*
* Odd Arild Olsen started out with the sheerdns [1] of Paul Sheer and rewrote
* it into a shape which I believe is both easier to understand and maintain.
* I also reused the input buffer for output and removed services he did not
* need. [1] http://threading.2038bug.com/sheerdns/
*
* Some bugfix and minor changes was applied by Roberto A. Foglietta who made
* the first porting of oao' scdns to busybox also.
*/
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <arpa/inet.h>
#include <ctype.h>
#include "libbb.h"
static char *fileconf = "/etc/dnsd.conf";
#define LOCK_FILE "/var/run/dnsd.lock"
#define LOG_FILE "/var/log/dnsd.log"
#define MAX_HOST_LEN 16 // longest host name allowed is 15
#define IP_STRING_LEN 18 // .xxx.xxx.xxx.xxx\0
//must be strlen('.in-addr.arpa') larger than IP_STRING_LEN
static const int MAX_NAME_LEN = (IP_STRING_LEN + 13);
/* Cannot get bigger packets than 512 per RFC1035
In practice this can be set considerably smaller:
Length of response packet is header (12B) + 2*type(4B) + 2*class(4B) +
ttl(4B) + rlen(2B) + r (MAX_NAME_LEN =21B) +
2*querystring (2 MAX_NAME_LEN= 42B), all together 90 Byte
*/
static const int MAX_PACK_LEN = 512 + 1;
#define DEFAULT_TTL 30; // increase this when not testing?
static const int REQ_A = 1;
static const int REQ_PTR = 12;
struct dns_repl { // resource record, add 0 or 1 to accepted dns_msg in resp
uint16_t rlen;
uint8_t *r; // resource
uint16_t flags;
};
struct dns_head { // the message from client and first part of response mag
uint16_t id;
uint16_t flags;
uint16_t nquer; // accepts 0
uint16_t nansw; // 1 in response
uint16_t nauth; // 0
uint16_t nadd; // 0
};
struct dns_prop {
uint16_t type;
uint16_t class;
};
struct dns_entry { // element of known name, ip address and reversed ip address
struct dns_entry *next;
char ip[IP_STRING_LEN]; // dotted decimal IP
char rip[IP_STRING_LEN]; // length decimal reversed IP
char name[MAX_HOST_LEN];
};
static struct dns_entry *dnsentry = NULL;
static int daemonmode = 0;
static uint32_t ttl = DEFAULT_TTL;
/*
* Convert host name from C-string to dns length/string.
*/
static void
convname(char *a, uint8_t *q)
{
int i = (q[0] == '.')?0:1;
for(; i < MAX_HOST_LEN-1 && *q; i++, q++)
a[i] = tolower(*q);
a[0] = i - 1;
a[i] = 0;
}
/*
* Insert length of substrings insetad of dots
*/
static void
undot(uint8_t * rip)
{
int i=0, s=0;
while(rip[i]) i++;
for(--i; i >= 0; i--) {
if(rip[i] == '.') {
rip[i] = s;
s = 0;
} else s++;
}
}
/*
* Append message to log file
*/
static void
log_message(char *filename, char *message)
{
FILE *logfile;
if (!daemonmode)
return;
logfile = fopen(filename, "a");
if (!logfile)
return;
fprintf(logfile, "%s\n", message);
fclose(logfile);
}
/*
* Read one line of hostname/IP from file
* Returns 0 for each valid entry read, -1 at EOF
* Assumes all host names are lower case only
* Hostnames with more than one label is not handled correctly.
* Presently the dot is copied into name without
* converting to a length/string substring for that label.
*/
static int
getfileentry(FILE * fp, struct dns_entry *s, int verb)
{
unsigned int a,b,c,d;
char *r, *name;
restart:
if(!(r = bb_get_line_from_file(fp)))
return -1;
while(*r == ' ' || *r == '\t') {
r++;
if(!*r || *r == '#' || *r == '\n')
goto restart; /* skipping empty/blank and commented lines */
}
name = r;
while(*r != ' ' && *r != '\t')
r++;
*r++ = 0;
if(sscanf(r,"%u.%u.%u.%u",&a,&b,&c,&d) != 4)
goto restart; /* skipping wrong lines */
sprintf(s->ip,"%u.%u.%u.%u",a,b,c,d);
sprintf(s->rip,".%u.%u.%u.%u",d,c,b,a);
undot((uint8_t*)s->rip);
convname(s->name,(uint8_t*)name);
if(verb)
fprintf(stderr,"\tname:%s, ip:%s\n",&(s->name[1]),s->ip);
return 0; /* warningkiller */
}
/*
* Read hostname/IP records from file
*/
static void
dnsentryinit(int verb)
{
FILE *fp;
struct dns_entry *m, *prev;
prev = dnsentry = NULL;
if(!(fp = fopen(fileconf, "r")))
bb_perror_msg_and_die("open %s",fileconf);
while (1) {
if(!(m = (struct dns_entry *)malloc(sizeof(struct dns_entry))))
bb_perror_msg_and_die("malloc dns_entry");
m->next = NULL;
if (getfileentry(fp, m, verb))
break;
if (prev == NULL)
dnsentry = m;
else
prev->next = m;
prev = m;
}
fclose(fp);
}
/*
* Set up UDP socket
*/
static int
listen_socket(char *iface_addr, int listen_port)
{
struct sockaddr_in a;
char msg[100];
int s;
int yes = 1;
if ((s = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
bb_perror_msg_and_die("socket() failed");
#ifdef SO_REUSEADDR
if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof(yes)) < 0)
bb_perror_msg_and_die("setsockopt() failed");
#endif
memset(&a, 0, sizeof(a));
a.sin_port = htons(listen_port);
a.sin_family = AF_INET;
if (!inet_aton(iface_addr, &a.sin_addr))
bb_perror_msg_and_die("bad iface address");
if (bind(s, (struct sockaddr *)&a, sizeof(a)) < 0)
bb_perror_msg_and_die("bind() failed");
listen(s, 50);
sprintf(msg, "accepting UDP packets on addr:port %s:%d\n",
iface_addr, (int)listen_port);
log_message(LOG_FILE, msg);
return s;
}
/*
* Look query up in dns records and return answer if found
* qs is the query string, first byte the string length
*/
static int
table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)
{
int i;
struct dns_entry *d=dnsentry;
do {
#ifdef DEBUG
char *p,*q;
q = (char *)&(qs[1]);
p = &(d->name[1]);
fprintf(stderr, "\ntest: %d <%s> <%s> %d", strlen(p), p, q, strlen(q));
#endif
if (type == REQ_A) { /* search by host name */
for(i = 1; i <= (int)(d->name[0]); i++)
if(tolower(qs[i]) != d->name[i])
continue;
#ifdef DEBUG
fprintf(stderr, " OK");
#endif
strcpy((char *)as, d->ip);
#ifdef DEBUG
fprintf(stderr, " %s ", as);
#endif
return 0;
}
else if (type == REQ_PTR) { /* search by IP-address */
if (!strncmp((char*)&d->rip[1], (char*)&qs[1], strlen(d->rip)-1)) {
strcpy((char *)as, d->name);
return 0;
}
}
} while ((d = d->next) != NULL);
return -1;
}
/*
* Decode message and generate answer
*/
#define eret(s) do { fprintf (stderr, "%s\n", s); return -1; } while (0)
static int
process_packet(uint8_t * buf)
{
struct dns_head *head;
struct dns_prop *qprop;
struct dns_repl outr;
void *next, *from, *answb;
uint8_t answstr[MAX_NAME_LEN + 1];
int lookup_result, type, len, packet_len;
uint16_t flags;
answstr[0] = '\0';
head = (struct dns_head *)buf;
if (head->nquer == 0)
eret("no queries");
if ((head->flags & 0x8000))
eret("ignoring response packet");
from = (void *)&head[1]; // start of query string
next = answb = from + strlen((char *)&head[1]) + 1 + sizeof(struct dns_prop); // where to append answer block
outr.rlen = 0; // may change later
outr.r = NULL;
outr.flags = 0;
qprop = (struct dns_prop *)(answb - 4);
type = ntohs(qprop->type);
// only let REQ_A and REQ_PTR pass
if (!(type == REQ_A || type == REQ_PTR)) {
goto empty_packet; /* we can't handle the query type */
}
if (ntohs(qprop->class) != 1 /* class INET */ ) {
outr.flags = 4; /* not supported */
goto empty_packet;
}
/* we only support standard queries */
if ((ntohs(head->flags) & 0x7800) != 0)
goto empty_packet;
// We have a standard query
log_message(LOG_FILE, (char *)head);
lookup_result = table_lookup(type, answstr, (uint8_t*)(&head[1]));
if (lookup_result != 0) {
outr.flags = 3 | 0x0400; //name do not exist and auth
goto empty_packet;
}
if (type == REQ_A) { // return an address
struct in_addr a;
if (!inet_aton((char*)answstr, &a)) {//dotted dec to long conv
outr.flags = 1; /* Frmt err */
goto empty_packet;
}
memcpy(answstr, &a.s_addr, 4); // save before a disappears
outr.rlen = 4; // uint32_t IP
}
else
outr.rlen = strlen((char *)answstr) + 1; // a host name
outr.r = answstr; // 32 bit ip or a host name
outr.flags |= 0x0400; /* authority-bit */
// we have an answer
head->nansw = htons(1);
// copy query block to answer block
len = answb - from;
memcpy(answb, from, len);
next += len;
// and append answer rr
*(uint32_t *) next = htonl(ttl);
next += 4;
*(uint16_t *) next = htons(outr.rlen);
next += 2;
memcpy(next, (void *)answstr, outr.rlen);
next += outr.rlen;
empty_packet:
flags = ntohs(head->flags);
// clear rcode and RA, set responsebit and our new flags
flags |= (outr.flags & 0xff80) | 0x8000;
head->flags = htons(flags);
head->nauth = head->nadd = htons(0);
head->nquer = htons(1);
packet_len = next - (void *)buf;
return packet_len;
}
/*
* Exit on signal
*/
static void
interrupt(int x)
{
unlink(LOCK_FILE);
write(2, "interrupt exiting\n", 18);
exit(2);
}
#define is_daemon() (flags&16)
#define is_verbose() (flags&32)
//#define DEBUG 1
int dnsd_main(int argc, char **argv)
{
int i, udps;
uint16_t port = 53;
uint8_t buf[MAX_PACK_LEN];
unsigned long flags = 0;
char *listen_interface = "0.0.0.0";
char *sttl=NULL, *sport=NULL;
if(argc > 1)
flags = bb_getopt_ulflags(argc, argv, "i:c:t:p:dv", &listen_interface, &fileconf, &sttl, &sport);
if(sttl)
if(!(ttl = atol(sttl)))
bb_show_usage();
if(sport)
if(!(port = atol(sport)))
bb_show_usage();
if(is_verbose()) {
fprintf(stderr,"listen_interface: %s\n", listen_interface);
fprintf(stderr,"ttl: %d, port: %d\n", ttl, port);
fprintf(stderr,"fileconf: %s\n", fileconf);
}
if(is_daemon())
#if defined(__uClinux__)
/* reexec for vfork() do continue parent */
vfork_daemon_rexec(1, 0, argc, argv, "-d");
#else /* uClinux */
if (daemon(1, 0) < 0) {
bb_perror_msg_and_die("daemon");
}
#endif /* uClinuvx */
dnsentryinit(is_verbose());
signal(SIGINT, interrupt);
signal(SIGPIPE, SIG_IGN);
signal(SIGHUP, SIG_IGN);
#ifdef SIGTSTP
signal(SIGTSTP, SIG_IGN);
#endif
#ifdef SIGURG
signal(SIGURG, SIG_IGN);
#endif
udps = listen_socket(listen_interface, port);
if (udps < 0)
exit(1);
while (1) {
fd_set fdset;
int r;
FD_ZERO(&fdset);
FD_SET(udps, &fdset);
// Block until a message arrives
if((r = select(udps + 1, &fdset, NULL, NULL, NULL)) < 0)
bb_perror_msg_and_die("select error");
else
if(r == 0)
bb_perror_msg_and_die("select spurious return");
/* Can this test ever be false? */
if (FD_ISSET(udps, &fdset)) {
struct sockaddr_in from;
int fromlen = sizeof(from);
r = recvfrom(udps, buf, sizeof(buf), 0,
(struct sockaddr *)&from,
(void *)&fromlen);
if(is_verbose())
fprintf(stderr, "\n--- Got UDP ");
log_message(LOG_FILE, "\n--- Got UDP ");
if (r < 12 || r > 512) {
bb_error_msg("invalid packet size");
continue;
}
if (r > 0) {
r = process_packet(buf);
if (r > 0)
sendto(udps, buf,
r, 0, (struct sockaddr *)&from,
fromlen);
}
} // end if
} // end while
return 0;
}