+/* vi: set sw=4 ts=4: */
/*
* 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
+ * 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 <string.h>
#include <signal.h>
#include <arpa/inet.h>
+#include <sys/socket.h>
#include <ctype.h>
-#include "libbb.h"
+#include "busybox.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
+enum {
+ MAX_HOST_LEN = 16, // longest host name allowed is 15
+ 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);
+ 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) +
+ 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;
+ MAX_PACK_LEN = 512 + 1,
-#define DEFAULT_TTL 30; // increase this when not testing?
+ DEFAULT_TTL = 30, // increase this when not testing?
-static const int REQ_A = 1;
-static const int REQ_PTR = 12;
+ REQ_A = 1,
+ 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_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_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;
+ 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
+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 uint32_t ttl = DEFAULT_TTL;
/*
- * Convert host name from C-string to dns length/string.
+ * Convert host name from C-string to dns length/string.
*/
static void
convname(char *a, uint8_t *q)
{
- int i = (q[0] == '.')?0:1;
+ int i = (q[0] == '.') ? 0 : 1;
for(; i < MAX_HOST_LEN-1 && *q; i++, q++)
a[i] = tolower(*q);
- a[0] = i - 1;
+ a[0] = i - 1;
a[i] = 0;
}
static void
undot(uint8_t * rip)
{
- int i=0, s=0;
+ int i = 0, s = 0;
while(rip[i]) i++;
for(--i; i >= 0; i--) {
if(rip[i] == '.') {
}
}
-/*
+/*
* 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);
+ 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
getfileentry(FILE * fp, struct dns_entry *s, int verb)
{
unsigned int a,b,c,d;
- char *r, *name;
+ char *r, *name;
restart:
if(!(r = bb_get_line_from_file(fp)))
return -1;
while(*r == ' ' || *r == '\t') {
r++;
- if(!*r || *r == '#' || *r == '\n')
+ if(!*r || *r == '#' || *r == '\n')
goto restart; /* skipping empty/blank and commented lines */
}
name = r;
sprintf(s->rip,".%u.%u.%u.%u",d,c,b,a);
undot((uint8_t*)s->rip);
convname(s->name,(uint8_t*)name);
-
- if(verb)
+
+ if(verb)
fprintf(stderr,"\tname:%s, ip:%s\n",&(s->name[1]),s->ip);
return 0; /* warningkiller */
static void
dnsentryinit(int verb)
{
- FILE *fp;
- struct dns_entry *m, *prev;
- prev = dnsentry = NULL;
+ FILE *fp;
+ struct dns_entry *m, *prev;
+ prev = dnsentry = NULL;
- if(!(fp = fopen(fileconf, "r")))
+ 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))))
+ 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);
+ m->next = NULL;
+ if (getfileentry(fp, m, verb))
+ break;
+
+ if (prev == NULL)
+ dnsentry = m;
+ else
+ prev->next = m;
+ prev = m;
+ }
+ fclose(fp);
}
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");
+ struct sockaddr_in a;
+ char msg[100];
+ int s;
+ int yes = 1;
+ s = bb_xsocket(PF_INET, SOCK_DGRAM, 0);
#ifdef SO_REUSEADDR
- if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof(yes)) < 0)
- bb_perror_msg_and_die("setsockopt() failed");
+ 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;
+ 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");
+ bb_xbind(s, (struct sockaddr *)&a, sizeof(a));
+ listen(s, 50); /* bb_xlisten? */
+ 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
+ * 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;
+ struct dns_entry *d=dnsentry;
- do {
+ do {
#ifdef DEBUG
- char *p,*q;
+ char *p,*q;
q = (char *)&(qs[1]);
p = &(d->name[1]);
- fprintf(stderr, "\ntest: %d <%s> <%s> %d", strlen(p), p, q, strlen(q));
+ fprintf(stderr, "\ntest: %d <%s> <%s> %d", strlen(p), p, q, strlen(q));
#endif
- if (type == REQ_A) { /* search by host name */
+ 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;
fprintf(stderr, " %s ", as);
#endif
return 0;
- }
- else if (type == REQ_PTR) { /* search by IP-address */
+ }
+ 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;
+ 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)
+#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;
+ 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);
+ 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;
+ 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);
+ unlink(LOCK_FILE);
+ write(2, "interrupt exiting\n", 18);
+ exit(2);
}
#define is_daemon() (flags&16)
int dnsd_main(int argc, char **argv)
{
- int i, udps;
- uint16_t port = 53;
- uint8_t buf[MAX_PACK_LEN];
+ int udps;
+ uint16_t port = 53;
+ uint8_t buf[MAX_PACK_LEN];
unsigned long flags = 0;
- char *listen_interface = "0.0.0.0";
+ char *listen_interface = "0.0.0.0";
char *sttl=NULL, *sport=NULL;
- if(argc > 1)
+ 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)))
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(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");
- }
+ bb_xdaemon(1, 0);
#endif /* uClinuvx */
-
- dnsentryinit(is_verbose());
- signal(SIGINT, interrupt);
- signal(SIGPIPE, SIG_IGN);
- signal(SIGHUP, SIG_IGN);
+ dnsentryinit(is_verbose());
+
+ signal(SIGINT, interrupt);
+ signal(SIGPIPE, SIG_IGN);
+ signal(SIGHUP, SIG_IGN);
#ifdef SIGTSTP
- signal(SIGTSTP, SIG_IGN);
+ signal(SIGTSTP, SIG_IGN);
#endif
#ifdef SIGURG
- signal(SIGURG, SIG_IGN);
+ signal(SIGURG, SIG_IGN);
#endif
- udps = listen_socket(listen_interface, port);
- if (udps < 0)
- exit(1);
+ udps = listen_socket(listen_interface, port);
+ if (udps < 0)
+ exit(1);
- while (1) {
- fd_set fdset;
- int r;
+ 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)
+ 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
+ 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;
}
projects / oweals / busybox.git / blobdiff