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minix3/commands/nonamed/nonamed.c

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/* nonamed - Not a name daemon, but plays one on TV.
* Author: Kees J. Bot
* 29 Nov 1994
*/
static const char version[] = "2.7";
/* Use the file reading gethostent() family of functions. */
#define sethostent _sethostent
#define gethostent _gethostent
#define endhostent _endhostent
#define nil ((void*)0)
#include <sys/types.h>
#include <stdio.h>
#include <syslog.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <limits.h>
#include <signal.h>
#include <assert.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/asynchio.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <net/hton.h>
#include <net/netlib.h>
#include <net/gen/in.h>
#include <net/gen/inet.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h>
#include <net/gen/socket.h>
#include <net/gen/tcp.h>
#include <net/gen/tcp_io.h>
#include <net/gen/udp.h>
#include <net/gen/udp_hdr.h>
#include <net/gen/udp_io.h>
#include <net/gen/dhcp.h>
#include <paths.h>
#include <minix/paths.h>
#undef HTONL
#undef HTONS
#define HTONL htonl
#define HTONS htons
#define HTTL 3600L /* Default time to live for /etc/hosts data. */
#define SHORT_TIMEOUT 2 /* If you expect an answer soon. */
#define MEDIUM_TIMEOUT 4 /* Soon, but not that soon. */
#define LONG_TIMEOUT 300 /* For stream connections to a real named. */
#define N_IDS 256 /* Keep track of this many queries. */
#define N_DATAMAX (4096*sizeof(char *)) /* Default response cache size. */
#define N_NAMEDS 8 /* Max # name daemons we can keep track of. */
#define NO_FD (-1) /* No name daemon channel here. */
#define T_NXD ((u16_t) -1) /* A "type" signalling a nonexistent domain. */
/* Can't do async I/O under standard Minix, so forget about TCP. */
#define DO_TCP (__minix_vmd || !__minix)
/* Host data, file to store our process id in, our cache, DHCP's cache. */
static char HOSTS[]= _PATH_HOSTS;
static char PIDFILE[]= "/usr/run/nonamed.pid";
static char NNCACHE[]= "/usr/adm/nonamed.cache";
static char DHCPCACHE[]= _PATH_DHCPCACHE;
/* Magic string to head the cache file. */
static char MAGIC[4]= "NND\2";
#define arraysize(a) (sizeof(a) / sizeof((a)[0]))
#define arraylimit(a) ((a) + arraysize(a))
#define between(a, c, z) ((unsigned) ((c) - (a)) <= (unsigned) ((z) - (a)))
/* The start of time and the far future. */
#define IMMEDIATE ((time_t) 0)
#define NEVER ((time_t) ((time_t) -1 < 0 ? LONG_MAX : ULONG_MAX))
static unsigned debug; /* Debug level. */
static time_t now; /* Current time. */
static u32_t stale; /* Extension time for stale data. */
static u32_t httl; /* TTL for /etc/hosts data. */
static int reinit, done; /* Reinit config / program is done. */
static int single; /* Run single on a nondefault interface. */
static int localonly; /* Only accept local queries. */
#define LOCALHOST 0x7F000001
static void report(const char *label)
{
fprintf(stderr, "nonamed: %s: %s\n", label, strerror(errno));
}
static void fatal(const char *label)
{
report(label);
if (debug >= 3) { fflush(nil); abort(); }
exit(1);
}
static void *allocate(void *mem, size_t size)
{
if ((mem= realloc(mem, size)) == nil) fatal("malloc()");
return mem;
}
static void deallocate(void *mem)
{
free(mem);
}
static char *timegmt(time_t t)
/* Simple "time in seconds to GMT time today" converter. */
{
unsigned h, m, s;
static char asctime[sizeof("00:00:00")];
s= t % 60;
t /= 60;
m= t % 60;
t /= 60;
h= t % 24;
sprintf(asctime, "%02u:%02u:%02u", h, m, s);
return asctime;
}
static char *nowgmt(void)
{
return timegmt(now);
}
#define PC(n) ((void) sizeof(char [sizeof(*(n)) == 1]), (char *) (n))
#define namecpy(n1, n2) strcpy(PC(n1), PC(n2))
#define namecat(n1, n2) strcat(PC(n1), PC(n2))
#define namechr(n, c) ((u8_t *) strchr(PC(n), (c)))
#define namecmp(n1, n2) strcasecmp(PC(n1), PC(n2))
#define namencmp(n1, n2, len) strncasecmp(PC(n1), PC(n2), len)
typedef struct dns { /* A DNS packet. */
HEADER hdr; /* DNS header. */
u8_t data[PACKETSZ - sizeof(HEADER)]; /* DNS data. */
} dns_t;
/* Addres of DNS packet to octet address, or vv. */
#define dns2oct(dp) ((u8_t *) (dp))
#define oct2dns(dp) ((dns_t *) (dp))
typedef struct query { /* One cached answer to a query. */
struct query *less; /* Less recently used. */
struct query *more; /* More recently used. */
time_t age; /* Time it was added. */
time_t stale; /* Time it goes stale by TTL. */
u16_t usage; /* Counts of queries answered. */
u8_t flags; /* QF_REFRESH. */
size_t size; /* Size of DNS packet. */
dns_t dns; /* Answer to query as a DNS packet. */
} query_t;
#define QF_REFRESH 0x01 /* This stale data must be refreshed. */
#define QU_SHIFT 1 /* To shift usage by when evicting. */
/* Size of new query_t or existing query_t. */
#define query_allocsize(dnssize) (offsetof(query_t, dns) + (dnssize))
#define query_size(qp) query_allocsize((qp)->size)
static query_t *mru, *lru; /* Most and least recently used answers. */
static int q_refresh; /* Set when an entry needs refreshing. */
static void pack16(u8_t *buf, u16_t s)
/* Pack a 16 bit value into a byte array. */
{
buf[0]= ((u8_t *) &s)[0];
buf[1]= ((u8_t *) &s)[1];
}
static void pack32(u8_t *buf, u32_t l)
/* Pack a 32 bit value into a byte array. */
{
buf[0]= ((u8_t *) &l)[0];
buf[1]= ((u8_t *) &l)[1];
buf[2]= ((u8_t *) &l)[2];
buf[3]= ((u8_t *) &l)[3];
}
static u16_t upack16(u8_t *buf)
/* Unpack a 16 bit value from a byte array. */
{
u16_t s;
((u8_t *) &s)[0]= buf[0];
((u8_t *) &s)[1]= buf[1];
return s;
}
static u32_t upack32(u8_t *buf)
/* Unpack a 32 bit value from a byte array. */
{
u32_t l;
((u8_t *) &l)[0]= buf[0];
((u8_t *) &l)[1]= buf[1];
((u8_t *) &l)[2]= buf[2];
((u8_t *) &l)[3]= buf[3];
return l;
}
/* Encoding of RRs: i(paddr), d(omain), l(ong), c(har), s(tring), (s)h(ort). */
static char *encoding[] = {
"c*", /* anything unknown is c* */
"i", /* A */
"d", /* NS */
"d", /* MD */
"d", /* MF */
"d", /* CNAME */
"ddlllll", /* SOA */
"d", /* MB */
"d", /* MG */
"d", /* MR */
"c*", /* NULL */
"icc*", /* WKS */
"d", /* PTR */
"ss", /* HINFO */
"dd", /* MINFO */
"hd", /* MX */
"s*", /* TXT */
};
static char *itoa(char *fmt, u32_t i)
{
static char output[32 + 3 * sizeof(i)];
sprintf(output, fmt, (unsigned long) i);
return output;
}
static char *classname(unsigned class)
/* Class name of a resource record, for debug purposes. */
{
static char *classes[] = { "IN", "CS", "CHAOS", "HS" };
if ((class - C_IN) < arraysize(classes)) return classes[class - C_IN];
return itoa("C_%u", class);
}
static char *typename(unsigned type)
/* Type name of a resource record, for debug purposes. */
{
static char type_A[][6] = {
"A", "NS", "MD", "MF", "CNAME", "SOA", "MB", "MG", "MR", "NULL",
"WKS", "PTR", "HINFO", "MINFO", "MX", "TXT",
};
static char type_AXFR[][6] = {
"AXFR", "MAILB", "MAILA", "ANY",
};
if ((type - T_A) < arraysize(type_A)) return type_A[type - T_A];
if ((type - T_AXFR) < arraysize(type_AXFR)) return type_AXFR[type - T_AXFR];
return itoa("T_%u", type);
}
static int print_qrr(dns_t *dp, size_t size, u8_t *cp0, int q)
/* Print a query (q) or resource record (!q) from 'cp0' in a DNS packet for
* debug purposes. Return number of bytes skipped or -1 on error.
*/
{
u8_t name[MAXDNAME+1];
u8_t *cp;
char *ep;
u8_t *dlim, *rlim;
u16_t type, class, rdlength;
u32_t ttl;
int r;
cp= cp0;
dlim= dns2oct(dp) + size;
r= dn_expand(dns2oct(dp), dlim, cp, name, MAXDNAME);
if (r == -1) return -1;
cp += r;
if (cp + 2 * sizeof(u16_t) > dlim) return -1;
type= ntohs(upack16(cp));
cp += sizeof(u16_t);
class= ntohs(upack16(cp));
cp += sizeof(u16_t);
printf("%-25s", (char *) name);
if (q) {
/* We're just printing a query segment, stop right here. */
printf(" %8s", classname(class));
printf(" %-5s", typename(type));
return cp - cp0;
}
if (cp + sizeof(u32_t) + sizeof(u16_t) > dlim) return -1;
ttl= ntohl(upack32(cp));
cp += sizeof(u32_t);
rdlength= ntohs(upack16(cp));
cp += sizeof(u16_t);
if (cp + rdlength > dlim) return -1;
rlim = cp + rdlength;
printf(" %5lu", (unsigned long) ttl);
printf(" %s", classname(class));
printf(" %-5s", typename(type));
ep= type < arraysize(encoding) ? encoding[type] : encoding[0];
while (*ep != 0) {
switch (*ep++) {
case 'i':
if (cp + sizeof(u32_t) > rlim) return -1;
printf(" %s", inet_ntoa(upack32(cp)));
cp += sizeof(u32_t);
break;
case 'l':
if (cp + sizeof(u32_t) > rlim) return -1;
printf(" %ld", (long)(i32_t) ntohl(upack32(cp)));
cp += sizeof(u32_t);
break;
case 'd':
r= dn_expand(dns2oct(dp), dlim, cp, name, MAXDNAME);
if (r == -1) return -1;
printf(" %s", (char *) name);
cp += r;
break;
case 'c':
if (cp >= rlim) return -1;
printf(" %02X", *cp++);
break;
case 's':
r= *cp + 1;
if (cp + r > rlim) return -1;
printf(" \"%.*s\"", *cp, (char *) (cp + 1));
cp += r;
break;
case 'h':
if (cp + sizeof(u16_t) > rlim) return -1;
printf(" %u", ntohs(upack16(cp)));
cp += sizeof(u16_t);
break;
}
if (*ep == '*') ep= cp < rlim ? ep-1 : ep+1;
}
return cp - cp0;
}
static void dns_tell(int indent, dns_t *dp, size_t size)
/* Explain a DNS packet, for debug purposes. */
{
u8_t *cp;
int r, i;
unsigned count[4];
static char label[4][4]= { "QD:", "AN:", "NS:", "AR:" };
static char rcodes[][9] = {
"NOERROR", "FORMERR", "SERVFAIL", "NXDOMAIN", "NOTIMP", "REFUSED"
};
if (size < sizeof(HEADER)) return;
printf("%*s", indent, "");
printf("DNS %s:", (dp->hdr.qr) ? "reply" : "query");
r = dp->hdr.rcode;
printf(" %s", r < arraysize(rcodes) ? rcodes[r] : itoa("ERR_%lu", r));
if (dp->hdr.aa) printf(" AA");
if (dp->hdr.tc) printf(" TC");
if (dp->hdr.rd) printf(" RD");
if (dp->hdr.ra) printf(" RA");
if (dp->hdr.ad) printf(" AD");
if (dp->hdr.cd) printf(" CD");
fputc('\n', stdout);
count[0]= ntohs(dp->hdr.qdcount);
count[1]= ntohs(dp->hdr.ancount);
count[2]= ntohs(dp->hdr.nscount);
count[3]= ntohs(dp->hdr.arcount);
cp = dp->data;
for (i= 0; i < 4; i++) {
while (count[i] > 0) {
printf("%*s", indent, "");
printf(" %s ", label[i]);
r= print_qrr(dp, size, cp, (i == 0));
fputc('\n', stdout);
if (r == -1) return;
cp += r;
count[i]--;
}
}
}
static u32_t dns_ttl(dns_t *dp, size_t size, u32_t delta)
/* Compute the minimum TTL of all RRs in a DNS packet and subtract delta from
* all TTLs. (We are actually only interested in the minimum (delta = 0) or
* the subtraction (delta > 0). It was easier to roll this into one routine.)
*/
{
u8_t *cp, *rdp, *dlim;
int r, i, hasttl, hassoa;
unsigned type, count[4];
u32_t ttl, minimum, minttl;
unsigned rcode;
u8_t name[MAXDNAME+1];
hasttl= hassoa= 0;
minttl= 365*24*3600L;
dlim= dns2oct(dp) + size;
if (size < sizeof(HEADER)) return 0;
rcode= dp->hdr.rcode;
count[0]= ntohs(dp->hdr.qdcount);
count[1]= ntohs(dp->hdr.ancount);
count[2]= ntohs(dp->hdr.nscount);
count[3]= ntohs(dp->hdr.arcount);
cp = dp->data;
for (i= 0; i < 4 && cp < dlim; i++) {
while (count[i] > 0) {
r= dn_expand(dns2oct(dp), dlim, cp, name, MAXDNAME);
if (r == -1) break;
cp += r + 2 * sizeof(u16_t);
if (i != 0) {
if (cp + sizeof(u32_t) + sizeof(u16_t) > dlim) break;
type= upack16(cp - 2 * sizeof(u16_t));
ttl= ntohl(upack32(cp));
ttl= ttl < delta ? 0 : ttl - delta;
if (rcode == NXDOMAIN && i == 2 && type == HTONS(T_SOA)) {
rdp= cp + sizeof(u32_t) + sizeof(u16_t);
r= dn_expand(dns2oct(dp), dlim, rdp, name, MAXDNAME);
if (r == -1) break;
rdp += r;
r= dn_expand(dns2oct(dp), dlim, rdp, name, MAXDNAME);
if (r == -1) break;
rdp += r + 4 * sizeof(u32_t);
if (rdp + sizeof(u32_t) > dlim) break;
minimum= ntohl(upack32(rdp));
if (ttl > minimum) ttl= minimum;
hassoa= 1;
}
if (delta != 0) pack32(cp, htonl(ttl));
if (ttl < minttl) minttl= ttl;
hasttl= 1;
cp += sizeof(u32_t);
cp += sizeof(u16_t) + ntohs(upack16(cp));
}
count[i]--;
}
}
return ((rcode == NOERROR && hasttl) || (rcode == NXDOMAIN && hassoa))
? minttl : 0;
}
/* Total cached query data. */
static size_t n_datamax= N_DATAMAX;
static size_t n_data;
static query_t *extract_query(query_t *qp)
/* Take a query out of the query cache. */
{
assert(qp != nil);
*(qp->less != nil ? &qp->less->more : &lru) = qp->more;
*(qp->more != nil ? &qp->more->less : &mru) = qp->less;
n_data -= query_size(qp);
return qp;
}
static query_t *get_query(u8_t *name, unsigned type)
/* Find a query and if so remove it from the cache and return it. */
{
query_t *qp, *less;
u8_t qname[MAXDNAME+1];
int r;
for (qp= mru; qp != nil; qp= less) {
less= qp->less;
if (qp->stale <= now - stale) {
/* This answer has expired. */
deallocate(extract_query(qp));
} else {
r= dn_expand(dns2oct(&qp->dns), dns2oct(&qp->dns) + qp->size,
qp->dns.data, qname, MAXDNAME);
if (r == -1) continue;
if (namecmp(qname, name) == 0 && upack16(qp->dns.data+r) == type) {
/* Found an answer to the query. */
return extract_query(qp);
}
}
}
return nil;
}
static void insert_query(query_t *qp)
/* (Re)insert a query into the cache. */
{
*(qp->less != nil ? &qp->less->more : &lru) = qp;
*(qp->more != nil ? &qp->more->less : &mru) = qp;
n_data += query_size(qp);
/* Try to delete the LRU while there is too much memory in use. If
* its usage count is too high then it gets a second chance.
*/
while (n_data > n_datamax && lru != nil) {
if ((lru->usage >>= QU_SHIFT) == 0 || lru->stale <= now - stale) {
deallocate(extract_query(lru));
} else {
lru->less= mru; /* Make list circular. */
mru->more= lru;
mru= lru; /* Move one over, making LRU the MRU. */
lru= lru->more;
lru->less= nil; /* Break the circle. */
mru->more= nil;
}
}
if (debug >= 2) {
unsigned n= 0;
for (qp= mru; qp != nil; qp= qp->less) n++;
printf("%u cached repl%s, %u bytes, sbrk(0) = %u\n",
n, n == 1 ? "y" : "ies",
(unsigned) n_data,
(unsigned) sbrk(0));
}
}
static void put_query(query_t *qp)
/* Add a new query to the cache as the MRU. */
{
qp->less= mru;
qp->more= nil;
insert_query(qp);
}
static void cache2file(void)
/* Store the cached data into the cache file. */
{
FILE *fp;
query_t *qp;
u8_t data[4+1+2+2];
u16_t usage;
char newcache[sizeof(NNCACHE) + sizeof(".new")];
if (single) return;
strcpy(newcache, NNCACHE);
strcat(newcache, ".new");
if ((fp= fopen(newcache, "w")) == nil) {
if ((errno != ENOENT && errno != EROFS) || debug >= 2) report(newcache);
return;
}
if (debug >= 2) printf("Writing %s:\n", newcache);
/* Magic number: */
fwrite(MAGIC, 1, sizeof(MAGIC), fp);
for (qp= lru; qp != nil; qp= qp->more) {
if (qp->stale <= now - stale) continue;
if (debug >= 2) {
printf("Usage = %u, Age = %ld, Flags = %02X:\n",
qp->usage, (long) (now - qp->age), qp->flags);
dns_tell(2, &qp->dns, qp->size);
}
pack32(data+0, htonl(qp->age));
data[4]= qp->flags;
pack16(data+5, htons(qp->size));
pack16(data+7, htons(qp->usage));
fwrite(data, 1, sizeof(data), fp);
fwrite(&qp->dns, 1, qp->size, fp);
if (ferror(fp)) break;
}
if (ferror(fp) || fclose(fp) == EOF) {
report(newcache);
(void) unlink(newcache);
return;
}
if (debug >= 2) printf("mv %s %s\n", newcache, NNCACHE);
if (rename(newcache, NNCACHE) < 0) {
fprintf(stderr, "nonamed: mv %s %s: %s\n",
newcache, NNCACHE, strerror(errno));
(void) unlink(newcache);
}
}
static void file2cache(void)
/* Read cached data from the cache file. */
{
query_t *qp;
FILE *fp;
u8_t data[4+1+2+2];
size_t dlen;
if (single) return;
if ((fp= fopen(NNCACHE, "r")) == nil) {
if (errno != ENOENT || debug >= 2) report(NNCACHE);
return;
}
if (debug >= 2) printf("Reading %s:\n", NNCACHE);
/* Magic number? */
fread(data, 1, sizeof(MAGIC), fp);
if (ferror(fp) || memcmp(MAGIC, data, sizeof(MAGIC)) != 0) goto err;
for (;;) {
fread(data, 1, sizeof(data), fp);
if (feof(fp) || ferror(fp)) break;
dlen= ntohs(upack16(data+5));
qp= allocate(nil, query_allocsize(dlen));
qp->age= htonl(upack32(data+0));
qp->flags= data[4];
if (qp->flags & QF_REFRESH) q_refresh= 1;
qp->size= dlen;
qp->usage= htons(upack16(data+7));
fread(&qp->dns, 1, qp->size, fp);
if (feof(fp) || ferror(fp)) {
deallocate(qp);
goto err;
}
qp->stale= qp->age + dns_ttl(&qp->dns, dlen, 0);
if (debug >= 2) {
printf("Usage = %u, Age = %ld, Flags = %02X:\n",
qp->usage, (long) (now - qp->age), qp->flags);
dns_tell(2, &qp->dns, dlen);
}
put_query(qp);
}
if (ferror(fp)) {
err:
/* The cache file did not end at EOF or is otherwise a mess. */
fprintf(stderr, "nonamed: %s: %s\n", NNCACHE,
ferror(fp) ? strerror(errno) : "Corrupt");
while (lru != nil) deallocate(extract_query(lru));
}
fclose(fp);
}
typedef int handler_t(void *data, int expired);
/* All actions are in the form of "jobs". */
typedef struct job {
struct job *next, **prev; /* To make a job queue. */
handler_t *handler; /* Function to handle this job. */
time_t timeout; /* Moment it times out. */
void *data; /* Data associated with the job. */
} job_t;
static job_t *queue; /* Main job queue. */
static void newjob(handler_t *handler, time_t timeout, void *data)
/* Create a new job with the given handler, timeout time and data. */
{
job_t *job, **prev;
job= allocate(nil, sizeof(*job));
job->handler= handler;
job->timeout= timeout;
job->data= data;
for (prev= &queue; *prev != nil; prev= &(*prev)->next) {
if (job->timeout < (*prev)->timeout) break;
}
job->next= *prev;
job->prev= prev;
*prev= job;
if (job->next != nil) job->next->prev= &job->next;
}
static int execjob(job_t *job, int expired)
/* Execute a job by calling the handler. Remove the job if it returns true,
* indicating that it is done. Expired is set if the job timed out. It is
* otherwise called to check for I/O.
*/
{
if ((*job->handler)(job->data, expired)) {
*job->prev= job->next;
if (job->next != nil) job->next->prev= job->prev;
deallocate(job);
return 1;
}
return 0;
}
static void force_expire(handler_t *handler)
/* Force jobs to expire immediately, the named searcher for instance. */
{
job_t *job, **prev= &queue;
while ((job= *prev) != nil) {
if (job->handler == handler && job->timeout != IMMEDIATE) {
*prev= job->next;
if (job->next != nil) job->next->prev= prev;
newjob(job->handler, IMMEDIATE, job->data);
deallocate(job);
} else {
prev= &job->next;
}
}
}
static int nxdomain(u8_t *name)
/* True iff the two top level components in a name are repeated in the name,
* or if in-addr.arpa is found within a name. Such things happen often in a
* search for an already fully qualified local name. For instance:
* flotsam.cs.vu.nl.cs.vu.nl. (We don't want this at boot time.)
*/
{
u8_t *end, *top, *p;
size_t n;
end= namechr(name, 0);
top= end;
while (top > name && *--top != '.') {}
while (top > name && *--top != '.') {}
n= end - top;
p= top;
for (;;) {
if (p == name) return 0;
if (*--p == '.') {
if (namencmp(p, top, n) == 0 && p[n] == '.') return 1;
if (namencmp(p, ".in-addr.arpa.", 14) == 0) return 1;
}
}
}
typedef struct id2id {
u16_t id; /* ID of old query. */
u16_t port; /* Reply port. */
ipaddr_t ip; /* Reply address. */
} id2id_t;
static id2id_t id2id[N_IDS];
static u16_t id_counter;
static u16_t new_id(u16_t in_id, u16_t in_port, ipaddr_t in_ip)
/* An incoming UDP query must be relabeled with a new ID before it can be
* send on to a real name daemon.
*/
{
id2id_t *idp;
u16_t id;
id= id_counter++;
idp= &id2id[id % N_IDS];
idp->id= in_id;
idp->port= in_port;
idp->ip= in_ip;
return htons(id);
}
static int old_id(u16_t id, u16_t *out_id, u16_t *out_port, ipaddr_t *out_ip)
/* Translate a reply id back to the id, port, and address used in the query.
* Return true if the translation is possible.
*/
{
id= ntohs(id);
if ((u16_t) (id_counter - id) > N_IDS) {
/* Too old. */
return 0;
} else {
/* We know this one. */
id2id_t *idp= &id2id[id % N_IDS];
if (idp->port == 0) return 0; /* Named is trying to fool us? */
*out_id= idp->id;
*out_port= idp->port;
*out_ip= idp->ip;
idp->port= 0;
return 1;
}
}
/* IDs used to mark my own queries to name servers, must be new_id translated
* to make them unique "on the wire".
*/
#define ID_IPSELF HTONL(0) /* "I did it myself" address. */
#define ID_PROBE HTONS(0) /* Name server probe. */
#define ID_REFRESH HTONS(1) /* Query to refresh a cache entry. */
static char *tcp_device, *udp_device; /* TCP and UDP device names. */
static int udp_fd; /* To send or receive UDP packets. */
static asynchio_t asyn; /* For I/O in progress. */
static ipaddr_t my_ip; /* My IP address. */
static u16_t my_port, named_port; /* Port numbers, normally "domain". */
static ipaddr_t named[N_NAMEDS]; /* Addresses of all name servers. */
static unsigned n_nameds; /* Number of configured name daemons. */
static unsigned i_named; /* Index to current name server. */
static int expect; /* Set when we expect an answer. */
static int search_ct= -1; /* Named search count and state. */
static int dirty; /* True when new entry put in cache. */
#define current_named() (+named[i_named])
#define searching() (search_ct > 0)
#define start_searching() ((void) (search_ct= -1))
#define stop_searching() ((void) (search_ct= 0))
#define expecting() (+expect)
#define start_expecting() ((void) (expect= 1))
#define stop_expecting() ((void) (expect= 0))
static time_t filetime(const char *file)
/* Get the modified time of a file. */
{
struct stat st;
return stat(file, &st) == 0 ? st.st_mtime : 0;
}
static void init_config(ipaddr_t ifip)
/* Read name daemon list and other special stuff from the hosts file. */
{
struct hostent *he;
u32_t nip, hip;
static time_t hosts_time, dhcp_time;
time_t ht, dt;
/* See if anything really changed. */
if (((ifip ^ HTONL(LOCALHOST)) & HTONL(0xFF000000)) == 0) ifip= my_ip;
ht= filetime(HOSTS);
dt= filetime(DHCPCACHE);
if (ifip == my_ip && ht == hosts_time && dt == dhcp_time) return;
my_ip= ifip;
hosts_time= ht;
dhcp_time= dt;
if (debug >= 2) {
printf("%s: I am nonamed %s at %s:%u\n",
nowgmt(), version, inet_ntoa(my_ip), ntohs(my_port));
}
httl= HTONL(HTTL);
stale= 0;
n_nameds= 0;
if (!single) {
sethostent(0);
while ((he= gethostent()) != nil) {
memcpy(&nip, he->h_addr, sizeof(u32_t));
hip= ntohl(nip);
if (namecmp(he->h_name, "%ttl") == 0) httl= nip;
if (namecmp(he->h_name, "%stale") == 0) stale= hip;
if (namecmp(he->h_name, "%memory") == 0) n_datamax= hip;
if (namecmp(he->h_name, "%nameserver") == 0) {
if (nip != my_ip || named_port != my_port) {
if (n_nameds < N_NAMEDS) named[n_nameds++]= nip;
}
}
}
endhostent();
}
if (n_nameds == 0) {
/* No name daemons found in the host file. What about DHCP? */
int fd;
dhcp_t d;
ssize_t r;
u8_t *data;
size_t len;
if ((fd= open(DHCPCACHE, O_RDONLY)) < 0) {
if (errno != ENOENT) fatal(DHCPCACHE);
} else {
while ((r= read(fd, &d, sizeof(d))) == sizeof(d)) {
if (d.yiaddr == my_ip) break;
}
if (r < 0) fatal(DHCPCACHE);
close(fd);
if (r == sizeof(d) && dhcp_gettag(&d, DHCP_TAG_DNS, &data, &len)) {
while (len >= sizeof(nip)) {
memcpy(&nip, data, sizeof(nip));
data += sizeof(nip);
len -= sizeof(nip);
if (nip != my_ip || named_port != my_port) {
if (n_nameds < N_NAMEDS) named[n_nameds++]= nip;
}
}
}
}
}
i_named= 0;
}
static handler_t job_save_cache, job_read_udp, job_find_named, job_expect_named;
#if DO_TCP
static handler_t job_setup_listen, job_listen, job_setup_connect, job_connect;
static handler_t job_read_query, job_write_query;
static handler_t job_read_reply, job_write_reply;
#endif
static int query_hosts(u8_t *qname, unsigned type, dns_t *dp, size_t *pdlen)
/* Read the /etc/hosts file to try and answer an A or PTR query. Return
* true iff an answer can be found, with the answer copied to *dp.
*/
{
struct hostent *he;
int i, r;
dns_t dns;
u8_t *domain;
u8_t *cp;
u8_t name[MAXDNAME+1];
u8_t *dnvec[40];
unsigned ancount;
struct hostent localhost;
static char *noaliases[]= { nil };
static ipaddr_t localaddr;
static char *localaddrlist[]= { (char *) &localaddr, nil };
localaddr = HTONL(LOCALHOST);
if (single) return 0;
/* Assume we can answer. */
dns.hdr.qr = 1;
dns.hdr.opcode = 0;
dns.hdr.aa = 1;
dns.hdr.tc = 0;
dns.hdr.rd = 0;
dns.hdr.ra = 1;
dns.hdr.unused = 0;
dns.hdr.ad = 0;
dns.hdr.cd = 0;
dns.hdr.rcode = 0;
dns.hdr.qdcount= HTONS(1);
ancount= 0;
dns.hdr.nscount= HTONS(0);
dns.hdr.arcount= HTONS(0);
dnvec[0]= dns2oct(&dns);
dnvec[1]= nil;
cp= dns.data;
r= dn_comp(qname, cp, arraysize(dns.data), dnvec, arraylimit(dnvec));
if (r == -1) return 0;
cp += r;
pack16(cp, type);
cp += sizeof(u16_t);
pack16(cp, HTONS(C_IN));
cp += sizeof(u16_t);
/* Localhost is fixed to 127.0.0.1. */
localhost.h_name=
namencmp(qname, "localhost.", 10) == 0 ? (char *) qname : "localhost";
localhost.h_aliases= noaliases;
localhost.h_addr_list= localaddrlist;
he= &localhost;
sethostent(0);
do {
int type_host = NTOHS(type);
switch (type_host) {
case T_A:
if (namecmp(qname, he->h_name) == 0) {
addA:
r= dn_comp((u8_t *) he->h_name, cp, arraylimit(dns.data) - cp,
dnvec, arraylimit(dnvec));
if (r == -1) return 0;
cp += r;
if (cp + 3 * sizeof(u16_t) + 2 * sizeof(u32_t)
> arraylimit(dns.data)) { r= -1; break; }
pack16(cp, HTONS(T_A));
cp += sizeof(u16_t);
pack16(cp, HTONS(C_IN));
cp += sizeof(u16_t);
pack32(cp, httl);
cp += sizeof(u32_t);
pack16(cp, HTONS(sizeof(u32_t)));
cp += sizeof(u16_t);
memcpy(cp, he->h_addr, sizeof(u32_t));
cp += sizeof(u32_t);
ancount++;
break;
}
/*FALL THROUGH*/
case T_CNAME:
domain= namechr(he->h_name, '.');
for (i= 0; he->h_aliases[i] != nil; i++) {
namecpy(name, he->h_aliases[i]);
if (domain != nil && namechr(name, '.') == nil) {
namecat(name, domain);
}
if (namecmp(qname, name) == 0) {
r= dn_comp(name, cp, arraylimit(dns.data) - cp,
dnvec, arraylimit(dnvec));
if (r == -1) break;
cp += r;
if (cp + 3 * sizeof(u16_t)
+ 1 * sizeof(u32_t) > arraylimit(dns.data)) return 0;
pack16(cp, HTONS(T_CNAME));
cp += sizeof(u16_t);
pack16(cp, HTONS(C_IN));
cp += sizeof(u16_t);
pack32(cp, httl);
cp += sizeof(u32_t);
/* pack16(cp, htonl(RDLENGTH)) */
cp += sizeof(u16_t);
r= dn_comp((u8_t *) he->h_name, cp,
arraylimit(dns.data) - cp,
dnvec, arraylimit(dnvec));
if (r == -1) break;
pack16(cp - sizeof(u16_t), htons(r));
cp += r;
ancount++;
if (type == HTONS(T_A)) goto addA; /* really wants A */
break;
}
}
break;
case T_PTR:
if (ancount > 0) break;
if (he->h_name[0] == '%') break;
sprintf((char *) name, "%d.%d.%d.%d.in-addr.arpa",
((u8_t *) he->h_addr)[3],
((u8_t *) he->h_addr)[2],
((u8_t *) he->h_addr)[1],
((u8_t *) he->h_addr)[0]);
if (namecmp(qname, name) == 0) {
r= dn_comp(name, cp, arraylimit(dns.data) - cp,
dnvec, arraylimit(dnvec));
if (r == -1) break;
cp += r;
if (cp + 3 * sizeof(u16_t) + 1 * sizeof(u32_t)
> arraylimit(dns.data)) { r= -1; break; }
pack16(cp, HTONS(T_PTR));
cp += sizeof(u16_t);
pack16(cp, HTONS(C_IN));
cp += sizeof(u16_t);
pack32(cp, httl);
cp += sizeof(u32_t);
/* pack16(cp, htonl(RDLENGTH)) */
cp += sizeof(u16_t);
r= dn_comp((u8_t *) he->h_name, cp,
arraylimit(dns.data) - cp, dnvec, arraylimit(dnvec));
if (r == -1) return 0;
pack16(cp - sizeof(u16_t), htons(r));
cp += r;
ancount++;
}
break;
}
} while (r != -1 && (he= gethostent()) != nil);
endhostent();
if (r == -1 || ancount == 0) return 0;
dns.hdr.ancount= htons(ancount);
memcpy(dp, &dns, *pdlen= cp - dns2oct(&dns));
return 1;
}
static int query_chaos(u8_t *qname, unsigned type, dns_t *dp, size_t *pdlen)
/* Report my version. Can't let BIND take all the credit. :-) */
{
int i, n, r;
dns_t dns;
u8_t *cp;
u8_t *dnvec[40];
if (type != HTONS(T_TXT) || namecmp(qname, "version.bind") != 0) return 0;
dns.hdr.qr = 1;
dns.hdr.opcode = 0;
dns.hdr.aa = 1;
dns.hdr.tc = 0;
dns.hdr.rd = 0;
dns.hdr.ra = 1;
dns.hdr.unused = 0;
dns.hdr.ad = 0;
dns.hdr.cd = 0;
dns.hdr.rcode = 0;
dns.hdr.qdcount= HTONS(1);
dns.hdr.ancount= HTONS(1);
dns.hdr.nscount= HTONS(0);
dns.hdr.arcount= htons(n_nameds);
dnvec[0]= dns2oct(&dns);
dnvec[1]= nil;
cp= dns.data;
r= dn_comp(qname, cp, arraysize(dns.data), dnvec, arraylimit(dnvec));
if (r == -1) return 0;
cp += r;
pack16(cp, type);
cp += sizeof(u16_t);
pack16(cp, HTONS(C_CHAOS));
cp += sizeof(u16_t);
r= dn_comp(qname, cp, arraylimit(dns.data) - cp, dnvec, arraylimit(dnvec));
if (r == -1) return 0;
cp += r;
pack16(cp, HTONS(T_TXT));
cp += sizeof(u16_t);
pack16(cp, HTONS(C_CHAOS));
cp += sizeof(u16_t);
pack32(cp, HTONL(0));
cp += sizeof(u32_t);
/* pack16(cp, htonl(RDLENGTH)) */
cp += sizeof(u16_t);
sprintf((char *) cp + 1, "nonamed %s at %s:%u",
version, inet_ntoa(my_ip), ntohs(my_port));
r= strlen((char *) cp + 1) + 1;
pack16(cp - sizeof(u16_t), htons(r));
*cp= r-1;
cp += r;
for (n= 0, i= i_named; n < n_nameds; n++, i= (i+1) % n_nameds) {
r= dn_comp((u8_t *) "%nameserver", cp, arraylimit(dns.data) - cp,
dnvec, arraylimit(dnvec));
if (r == -1) return 0;
cp += r;
if (cp + 3 * sizeof(u16_t)
+ 2 * sizeof(u32_t) > arraylimit(dns.data)) return 0;
pack16(cp, HTONS(T_A));
cp += sizeof(u16_t);
pack16(cp, HTONS(C_IN));
cp += sizeof(u16_t);
pack32(cp, HTONL(0));
cp += sizeof(u32_t);
pack16(cp, HTONS(sizeof(u32_t)));
cp += sizeof(u16_t);
memcpy(cp, &named[i], sizeof(u32_t));
cp += sizeof(u32_t);
}
memcpy(dp, &dns, *pdlen= cp - dns2oct(&dns));
return 1;
}
static void cache_reply(dns_t *dp, size_t dlen)
/* Store a DNS packet in the cache. */
{
int r;
query_t *qp, *less, *more;
unsigned usage;
u16_t type;
u8_t *cp;
u8_t name[MAXDNAME];
u32_t minttl;
if ((dp->hdr.rd && !dp->hdr.tc)) return;
if (dp->hdr.qdcount != HTONS(1)) return;
cp= dp->data;
r= dn_expand(dns2oct(dp), dns2oct(dp) + dlen, cp, name, MAXDNAME);
if (r == -1) return;
cp += r;
type= upack16(cp);
cp += sizeof(u16_t);
if (upack16(cp) != HTONS(C_IN)) return;
/* Delete old cached data, if any. Note where it is in the LRU. */
if ((qp= get_query(name, type)) != nil) {
less= qp->less;
more= qp->more;
usage= qp->usage;
deallocate(qp);
} else {
/* Not yet in the cache. */
less= mru;
more= nil;
usage= 1;
}
/* Determine minimum TTL. Discard if zero, never cache zero TTLs. */
if ((minttl= dns_ttl(dp, dlen, 0)) == 0) return;
/* Enter new reply in cache. */
qp= allocate(nil, query_allocsize(dlen));
qp->less= less;
qp->more= more;
qp->age= now;
qp->flags= 0;
qp->usage= usage;
qp->size= dlen;
memcpy(&qp->dns, dp, dlen);
qp->stale= qp->age + minttl;
insert_query(qp);
if (debug >= 1) printf("Answer cached\n");
/* Save the cache soon. */
if (!dirty) {
dirty= 1;
newjob(job_save_cache, now + LONG_TIMEOUT, nil);
}
}
static int job_save_cache(void *data, int expired)
/* Some time after the cache is changed it is written back to disk. */
{
if (!expired) return 0;
cache2file();
dirty= 0;
return 1;
}
static int compose_reply(dns_t *dp, size_t *pdlen)
/* Try to compose a reply to a request in *dp using the hosts file or
* cached data. Return answer in *dp with its size in *pdlen. Return true
* iff an answer is given.
*/
{
size_t dlen= *pdlen;
int r, rd;
query_t *qp;
unsigned id, type, class;
u8_t *cp;
u8_t name[MAXDNAME];
cp= dp->data;
r= dn_expand(dns2oct(dp), dns2oct(dp) + dlen, cp, name, MAXDNAME);
if (r != -1) {
cp += r;
if (cp + 2 * sizeof(u16_t) > dns2oct(dp) + dlen) {
r= -1;
} else {
type= upack16(cp);
cp += sizeof(u16_t);
class= upack16(cp);
cp += sizeof(u16_t);
}
}
/* Remember ID and RD. */
id= dp->hdr.id;
rd= dp->hdr.rd;
if (r == -1) {
/* Malformed query, reply "FORMERR". */
dp->hdr.tc = 0;
dp->hdr.qr = 1;
dp->hdr.aa = 1;
dp->hdr.unused = 0;
dp->hdr.ra = 1;
dp->hdr.rcode = FORMERR;
} else
if (class == HTONS(C_IN) && query_hosts(name, type, dp, pdlen)) {
/* Answer to this query is in the hosts file. */
dlen= *pdlen;
} else
if (class == HTONS(C_IN) && (qp= get_query(name, type)) != nil) {
/* Answer to this query is present in the cache. */
memcpy(dp, &qp->dns, dlen= qp->size);
dp->hdr.aa = 1;
(void) dns_ttl(dp, dlen, now - qp->age);
if (rd) {
if (qp->stale <= now) {
qp->flags |= QF_REFRESH;
q_refresh= 1;
}
qp->usage++;
}
put_query(qp);
} else
if (class == HTONS(C_CHAOS) && query_chaos(name, type, dp, pdlen)) {
/* Return our version numbers. */
dlen= *pdlen;
} else
if (n_nameds == 0 || nxdomain(name)) {
/* No real name daemon present, or this name has a repeated top level
* domain sequence. Reply "no such domain".
*/
dp->hdr.tc = 0;
dp->hdr.qr = 1;
dp->hdr.aa = 1;
dp->hdr.unused = 0;
dp->hdr.ra = 1;
dp->hdr.rcode = NXDOMAIN;
} else
if (!rd) {
/* "Recursion Desired" is off, so don't bother to relay. */
dp->hdr.tc = 0;
dp->hdr.qr = 1;
dp->hdr.unused = 0;
dp->hdr.ra = 1;
dp->hdr.rcode = NOERROR;
} else {
/* Caller needs to consult with a real name daemon. */
return 0;
}
/* Copy ID and RD back to answer. */
dp->hdr.id= id;
dp->hdr.rd = rd;
*pdlen= dlen;
return 1;
}
typedef struct udp_dns { /* One DNS packet over UDP. */
udp_io_hdr_t hdr; /* UDP header (source/destination). */
dns_t dns; /* DNS packet. */
} udp_dns_t;
static void refresh_cache(void)
/* Find a stale entry in the cache that was used to answer a query, and send
* a request to a name server that should refresh this entry.
*/
{
query_t *qp;
unsigned type;
int r;
u8_t *cp;
size_t dlen, ulen;
u8_t qname[MAXDNAME+1];
u8_t *dnvec[40];
udp_dns_t udp;
if (!q_refresh) return;
for (qp= lru; qp != nil; qp= qp->more) {
if ((qp->flags & QF_REFRESH) && qp->stale > now - stale) break;
}
if (qp == nil) {
q_refresh= 0;
return;
}
/* Found one to refresh. */
qp->flags &= ~QF_REFRESH;
r= dn_expand(dns2oct(&qp->dns), dns2oct(&qp->dns) + qp->size,
qp->dns.data, qname, MAXDNAME);
if (r == -1) return;
type= upack16(qp->dns.data+r);
dnvec[0]= dns2oct(&udp.dns);
dnvec[1]= nil;
cp= udp.dns.data;
r= dn_comp(qname, cp, arraysize(udp.dns.data), dnvec, arraylimit(dnvec));
if (r == -1) return;
cp += r;
pack16(cp, type);
cp += sizeof(u16_t);
pack16(cp, HTONS(C_IN));
cp += sizeof(u16_t);
dlen= cp - dns2oct(&udp.dns);
udp.dns.hdr.id= new_id(ID_REFRESH, my_port, ID_IPSELF);
udp.dns.hdr.qr = 0;
udp.dns.hdr.opcode = 0;
udp.dns.hdr.aa = 0;
udp.dns.hdr.tc = 0;
udp.dns.hdr.rd = 1;
udp.dns.hdr.ra = 0;
udp.dns.hdr.unused = 0;
udp.dns.hdr.ad = 0;
udp.dns.hdr.cd = 0;
udp.dns.hdr.rcode = 0;
udp.dns.hdr.qdcount= HTONS(1);
udp.dns.hdr.ancount= HTONS(0);
udp.dns.hdr.nscount= HTONS(0);
udp.dns.hdr.arcount= HTONS(0);
udp.hdr.uih_dst_addr= current_named();
udp.hdr.uih_dst_port= named_port;
udp.hdr.uih_ip_opt_len= 0;
udp.hdr.uih_data_len= dlen;
if (debug >= 1) {
printf("Refresh to %s:%u:\n",
inet_ntoa(current_named()), ntohs(named_port));
dns_tell(0, &udp.dns, dlen);
}
ulen= offsetof(udp_dns_t, dns) + dlen;
if (write(udp_fd, &udp, ulen) < 0) fatal(udp_device);
}
static int job_read_udp(void *data, int expired)
/* Read UDP queries and replies. */
{
ssize_t ulen;
size_t dlen;
static udp_dns_t udp;
u16_t id, port;
ipaddr_t ip;
time_t dtime;
assert(!expired);
/* Try to read a packet. */
ulen= asyn_read(&asyn, udp_fd, &udp, sizeof(udp));
dlen= ulen - offsetof(udp_dns_t, dns);
if (ulen == -1) {
if (errno == EINPROGRESS && !expired) return 0;
if (errno == EIO) fatal(udp_device);
if (debug >= 2) {
printf("%s: UDP read: %s\n", nowgmt(), strerror(errno));
}
} else {
if (debug >= 2) {
printf("%s: UDP read, %d bytes\n", nowgmt(), (int) ulen);
}
}
/* Restart this job no matter what. */
newjob(job_read_udp, NEVER, nil);
if (ulen < (ssize_t) (sizeof(udp_io_hdr_t) + sizeof(HEADER))) return 1;
if (debug >= 1) {
printf("%s:%u UDP ", inet_ntoa(udp.hdr.uih_src_addr),
ntohs(udp.hdr.uih_src_port));
dns_tell(0, &udp.dns, dlen);
}
/* Check, and if necessary reinitialize my configuration. */
init_config(udp.hdr.uih_dst_addr);
if (udp.dns.hdr.qr) {
/* This is a remote named reply, not a query. */
/* Response to a query previously relayed? */
if (!old_id(udp.dns.hdr.id, &id, &port, &ip)) return 1;
if (ip == ID_IPSELF && id == ID_PROBE) {
if (searching()) {
/* We have found a name server! */
int i;
/* In my list? */
for (i= 0; i < n_nameds; i++) {
if (named[i] == udp.hdr.uih_src_addr) {
i_named= i;
if (debug >= 1) {
printf("Current named = %s\n",
inet_ntoa(current_named()));
}
stop_searching();
force_expire(job_find_named);
}
}
}
}
/* We got an answer, so stop worrying. */
if (expecting()) {
stop_expecting();
force_expire(job_expect_named);
}
/* Put the information in the cache. */
cache_reply(&udp.dns, dlen);
/* Refresh a cached entry that was used when stale. */
refresh_cache();
/* Discard reply to myself. */
if (ip == ID_IPSELF) return 1;
/* Send the reply to the process that asked for it. */
udp.dns.hdr.id= id;
udp.hdr.uih_dst_addr= ip;
udp.hdr.uih_dst_port= port;
if (debug >= 1) printf("To client %s:%u\n", inet_ntoa(ip), ntohs(port));
} else {
/* A query. */
if (udp.dns.hdr.qdcount != HTONS(1)) return 1;
if(localonly) {
/* Check if it's a local query. */
if(ntohl(udp.hdr.uih_src_addr) != LOCALHOST) {
syslog(LOG_WARNING, "nonamed: dropped query from %s",
inet_ntoa(udp.hdr.uih_src_addr));
return 1;
}
}
/* Try to compose a reply from local data. */
if (compose_reply(&udp.dns, &dlen)) {
udp.hdr.uih_dst_addr= udp.hdr.uih_src_addr;
udp.hdr.uih_dst_port= udp.hdr.uih_src_port;
udp.hdr.uih_ip_opt_len= 0;
udp.hdr.uih_data_len= dlen;
ulen= offsetof(udp_dns_t, dns) + dlen;
/* Send an UDP DNS reply. */
if (debug >= 1) {
printf("%s:%u UDP ", inet_ntoa(udp.hdr.uih_dst_addr),
ntohs(udp.hdr.uih_dst_port));
dns_tell(0, &udp.dns, dlen);
}
} else {
/* Let a real name daemon handle the query. */
udp.dns.hdr.id= new_id(udp.dns.hdr.id,
udp.hdr.uih_src_port, udp.hdr.uih_src_addr);
udp.hdr.uih_dst_addr= current_named();
udp.hdr.uih_dst_port= named_port;
if (!expecting()) {
start_expecting();
newjob(job_expect_named, now + MEDIUM_TIMEOUT, nil);
}
if (debug >= 1) {
printf("To named %s:%u\n",
inet_ntoa(current_named()), ntohs(named_port));
}
}
}
if (write(udp_fd, &udp, ulen) < 0) fatal(udp_device);
return 1;
}
#if DO_TCP
typedef struct data_cl { /* Data for connect or listen jobs. */
int fd; /* Open TCP channel. */
int dn_fd; /* TCP channel to the name daemon. */
int retry; /* Retrying a connect? */
nwio_tcpcl_t tcpcl; /* Flags. */
} data_cl_t;
typedef struct data_rw { /* Data for TCP read or write jobs. */
int r_fd; /* Read from this TCP channel. */
int w_fd; /* And write to this TCP channel. */
struct data_rw *rev; /* Optional reverse TCP channel. */
u8_t *buf; /* Buffer for bytes to transfer. */
ssize_t offset; /* Offset in buf to r/w at. */
size_t size; /* Size of buf. */
} data_rw_t;
static int job_setup_listen(void *data, int expired)
/* Set up a listening channel for TCP DNS queries. */
{
data_cl_t *data_cl= data;
nwio_tcpconf_t tcpconf;
nwio_tcpopt_t tcpopt;
int fd;
if (!expired) return 0;
if (debug >= 2) printf("%s: Setup listen\n", nowgmt());
if (data_cl == nil) {
if ((fd= open(tcp_device, O_RDWR)) < 0) {
if (errno != EMFILE) report(tcp_device);
newjob(job_setup_listen, now + SHORT_TIMEOUT, nil);
return 1;
}
tcpconf.nwtc_flags= NWTC_SHARED | NWTC_LP_SET | NWTC_UNSET_RA
| NWTC_UNSET_RP;
tcpconf.nwtc_locport= my_port;
if (ioctl(fd, NWIOSTCPCONF, &tcpconf) == -1) fatal(tcp_device);
tcpopt.nwto_flags= NWTO_DEL_RST;
if (ioctl(fd, NWIOSTCPOPT, &tcpopt) == -1) fatal(tcp_device);
data_cl= allocate(nil, sizeof(*data_cl));
data_cl->fd= fd;
data_cl->tcpcl.nwtcl_flags= 0;
}
/* And listen. */
newjob(job_listen, NEVER, data_cl);
return 1;
}
static int job_listen(void *data, int expired)
/* A connection on the TCP DNS query channel. */
{
data_cl_t *data_cl= data;
/* Wait for a client. */
if (asyn_ioctl(&asyn, data_cl->fd, NWIOTCPLISTEN, &data_cl->tcpcl) < 0) {
if (errno == EINPROGRESS) return 0;
report(tcp_device);
/* Try again after a short time. */
newjob(job_setup_listen, now + SHORT_TIMEOUT, data_cl);
return 1;
}
if (debug >= 2) printf("%s: Listen\n", nowgmt());
/* Immediately resume listening. */
newjob(job_setup_listen, IMMEDIATE, nil);
/* Set up a connect to the real name daemon. */
data_cl->retry= 0;
newjob(job_setup_connect, IMMEDIATE, data_cl);
return 1;
}
static void start_relay(int fd, int dn_fd)
/* Start one or two read jobs after job_setup_connect() or job_connect(). */
{
data_rw_t *query; /* Client to DNS daemon relay. */
data_rw_t *reply; /* DNS daemon to client relay. */
query= allocate(nil, sizeof(*query));
query->r_fd= fd;
query->buf= allocate(nil, sizeof(u16_t));
query->offset= 0;
query->size= sizeof(u16_t);
if (dn_fd == NO_FD) {
/* Answer mode. */
query->w_fd= fd;
query->rev= nil;
} else {
/* Relay mode. */
reply= allocate(nil, sizeof(*reply));
reply->r_fd= dn_fd;
reply->w_fd= fd;
reply->buf= allocate(nil, sizeof(u16_t));
reply->offset= 0;
reply->size= sizeof(u16_t);
reply->rev= query;
query->w_fd= dn_fd;
query->rev= reply;
newjob(job_read_reply, now + LONG_TIMEOUT, reply);
}
newjob(job_read_query, now + LONG_TIMEOUT, query);
}
static void close_relay(data_rw_t *data_rw)
/* Close a relay channel. */
{
if (data_rw->rev != nil) {
/* Other end still active, signal EOF. */
(void) ioctl(data_rw->w_fd, NWIOTCPSHUTDOWN, nil);
data_rw->rev->rev= nil;
} else {
/* Close both ends down. */
asyn_close(&asyn, data_rw->r_fd);
close(data_rw->r_fd);
if (data_rw->w_fd != data_rw->r_fd) {
asyn_close(&asyn, data_rw->w_fd);
close(data_rw->w_fd);
}
}
deallocate(data_rw->buf);
deallocate(data_rw);
}
static int job_setup_connect(void *data, int expired)
/* Set up a connect for a TCP channel to the real name daemon. */
{
nwio_tcpconf_t tcpconf;
int dn_fd;
data_cl_t *data_cl= data;
if (!expired) return 0;
if (debug >= 2) printf("%s: Setup connect\n", nowgmt());
if (n_nameds == 0) {
/* No name daemons to relay to, answer myself. */
start_relay(data_cl->fd, NO_FD);
deallocate(data_cl);
return 1;
}
if ((dn_fd= open(tcp_device, O_RDWR)) < 0) {
if (errno != EMFILE) report(tcp_device);
if (++data_cl->retry < 5) {
/* Retry. */
newjob(job_setup_connect, now + SHORT_TIMEOUT, data_cl);
} else {
/* Reply myself (bound to fail). */
start_relay(data_cl->fd, NO_FD);
deallocate(data_cl);
}
return 1;
}
tcpconf.nwtc_flags= NWTC_LP_SEL | NWTC_SET_RA | NWTC_SET_RP;
tcpconf.nwtc_remaddr= current_named();
tcpconf.nwtc_remport= named_port;
if (ioctl(dn_fd, NWIOSTCPCONF, &tcpconf) == -1) fatal(tcp_device);
/* And connect. */
data_cl->dn_fd= dn_fd;
data_cl->tcpcl.nwtcl_flags= 0;
newjob(job_connect, NEVER, data_cl);
return 1;
}
static int job_connect(void *data, int expired)
/* Connect to a TCP DNS query channel. */
{
data_cl_t *data_cl= data;
/* Try to connect. */
if (asyn_ioctl(&asyn, data_cl->dn_fd, NWIOTCPCONN, &data_cl->tcpcl) < 0) {
if (errno == EINPROGRESS) return 0;
if (errno == EIO) fatal(tcp_device);
/* Connection refused. */
if (debug >= 2) printf("%s: Connect: %s\n", nowgmt(), strerror(errno));
asyn_close(&asyn, data_cl->dn_fd);
close(data_cl->dn_fd);
data_cl->dn_fd= NO_FD;
if (++data_cl->retry < 5) {
/* Search a new name daemon. */
if (!searching()) {
start_searching();
force_expire(job_find_named);
}
newjob(job_setup_connect, NEVER, data_cl);
return 1;
}
/* Reply with a failure eventually. */
}
if (debug >= 2) printf("%s: Connect\n", nowgmt());
/* Read the query from the user, send on to the name daemon, etc. */
start_relay(data_cl->fd, data_cl->dn_fd);
deallocate(data_cl);
return 1;
}
static void tcp_dns_tell(int fd, u8_t *buf)
/* Tell about a DNS packet on a TCP channel. */
{
nwio_tcpconf_t tcpconf;
if (ioctl(fd, NWIOGTCPCONF, &tcpconf) < 0) {
printf("??\?:?? TCP ");
} else {
printf("%s:%u TCP ", inet_ntoa(tcpconf.nwtc_remaddr),
ntohs(tcpconf.nwtc_remport));
}
dns_tell(0, oct2dns(buf + sizeof(u16_t)), ntohs(upack16(buf)));
}
static int job_read_query(void *data, int expired)
/* Read TCP queries from the client. */
{
data_rw_t *data_rw= data;
ssize_t count;
/* Try to read count bytes. */
count= asyn_read(&asyn, data_rw->r_fd,
data_rw->buf + data_rw->offset,
data_rw->size - data_rw->offset);
if (count < 0) {
if (errno == EINPROGRESS && !expired) return 0;
if (errno == EIO) fatal(tcp_device);
/* Remote end is late, or an error occurred. */
if (debug >= 2) {
printf("%s: TCP read query: %s\n", nowgmt(), strerror(errno));
}
close_relay(data_rw);
return 1;
}
if (debug >= 2) {
printf("%s: TCP read query, %d/%u bytes\n",
nowgmt(), data_rw->offset + count, data_rw->size);
}
if (count == 0) {
/* EOF. */
close_relay(data_rw);
return 1;
}
data_rw->offset += count;
if (data_rw->offset == data_rw->size) {
data_rw->size= sizeof(u16_t) + ntohs(upack16(data_rw->buf));
if (data_rw->size < sizeof(u16_t)) {
/* Malformed. */
close_relay(data_rw);
return 1;
}
if (data_rw->offset < data_rw->size) {
/* Query not complete, read more. */
data_rw->buf= allocate(data_rw->buf, data_rw->size);
newjob(job_read_query, now + LONG_TIMEOUT, data_rw);
return 1;
}
}
if (data_rw->size < sizeof(u16_t) + sizeof(dns_hdr_t)) {
close_relay(data_rw);
return 1;
}
if (debug >= 1) tcp_dns_tell(data_rw->r_fd, data_rw->buf);
/* Relay or reply. */
if (data_rw->w_fd != data_rw->r_fd) {
/* We have a real name daemon to do the work. */
data_rw->offset= 0;
newjob(job_write_query, now + LONG_TIMEOUT, data_rw);
} else {
/* No real name daemons or none reachable, so use the hosts file. */
dns_t *dp;
size_t dlen;
if (data_rw->size < sizeof(u16_t) + PACKETSZ) {
data_rw->buf= allocate(data_rw->buf, sizeof(u16_t) + PACKETSZ);
}
/* Build a reply packet. */
dp= oct2dns(data_rw->buf + sizeof(u16_t));
dlen= data_rw->size - sizeof(u16_t);
if (!compose_reply(dp, &dlen)) {
/* We're told to ask a name daemon, but that won't work. */
close_relay(data_rw);
return 1;
}
/* Start a reply write. */
pack16(data_rw->buf, htons(dlen));
data_rw->size= sizeof(u16_t) + dlen;
data_rw->buf= allocate(data_rw->buf, data_rw->size);
data_rw->offset= 0;
newjob(job_write_reply, now + LONG_TIMEOUT, data_rw);
}
return 1;
}
static int job_write_query(void *data, int expired)
/* Relay a TCP query to the name daemon. */
{
data_rw_t *data_rw= data;
ssize_t count;
/* Try to write count bytes to the name daemon. */
count= asyn_write(&asyn, data_rw->w_fd,
data_rw->buf + data_rw->offset,
data_rw->size - data_rw->offset);
if (count <= 0) {
if (errno == EINPROGRESS && !expired) return 0;
if (errno == EIO) fatal(tcp_device);
/* A write expired or failed (usually a broken connection.) */
if (debug >= 2) {
printf("%s: TCP write query: %s\n", nowgmt(), strerror(errno));
}
close_relay(data_rw);
return 1;
}
if (debug >= 2) {
printf("%s: TCP write query, %d/%u bytes\n",
nowgmt(), data_rw->offset + count, data_rw->size);
}
data_rw->offset += count;
if (data_rw->offset < data_rw->size) {
/* Partial write, continue. */
newjob(job_write_query, now + LONG_TIMEOUT, data_rw);
return 1;
}
if (debug >= 1) tcp_dns_tell(data_rw->w_fd, data_rw->buf);
/* Query fully send on, go read more queries. */
data_rw->offset= 0;
data_rw->size= sizeof(u16_t);
newjob(job_read_query, now + LONG_TIMEOUT, data_rw);
return 1;
}
static int job_read_reply(void *data, int expired)
/* Read a TCP reply from the real name daemon. */
{
data_rw_t *data_rw= data;
ssize_t count;
/* Try to read count bytes. */
count= asyn_read(&asyn, data_rw->r_fd,
data_rw->buf + data_rw->offset,
data_rw->size - data_rw->offset);
if (count < 0) {
if (errno == EINPROGRESS && !expired) return 0;
if (errno == EIO) fatal(tcp_device);
/* Remote end is late, or an error occurred. */
if (debug >= 2) {
printf("%s: TCP read reply: %s\n", nowgmt(), strerror(errno));
}
close_relay(data_rw);
return 1;
}
if (debug >= 2) {
printf("%s: TCP read reply, %d/%u bytes\n",
nowgmt(), data_rw->offset + count, data_rw->size);
}
if (count == 0) {
/* EOF. */
close_relay(data_rw);
return 1;
}
data_rw->offset += count;
if (data_rw->offset == data_rw->size) {
data_rw->size= sizeof(u16_t) + ntohs(upack16(data_rw->buf));
if (data_rw->size < sizeof(u16_t)) {
/* Malformed. */
close_relay(data_rw);
return 1;
}
if (data_rw->offset < data_rw->size) {
/* Reply not complete, read more. */
data_rw->buf= allocate(data_rw->buf, data_rw->size);
newjob(job_read_reply, now + LONG_TIMEOUT, data_rw);
return 1;
}
}
if (debug >= 1) tcp_dns_tell(data_rw->r_fd, data_rw->buf);
/* Reply fully read, send it on. */
data_rw->offset= 0;
newjob(job_write_reply, now + LONG_TIMEOUT, data_rw);
return 1;
}
static int job_write_reply(void *data, int expired)
/* Send a TCP reply to the client. */
{
data_rw_t *data_rw= data;
ssize_t count;
/* Try to write count bytes to the client. */
count= asyn_write(&asyn, data_rw->w_fd,
data_rw->buf + data_rw->offset,
data_rw->size - data_rw->offset);
if (count <= 0) {
if (errno == EINPROGRESS && !expired) return 0;
if (errno == EIO) fatal(tcp_device);
/* A write expired or failed (usually a broken connection.) */
if (debug >= 2) {
printf("%s: TCP write reply: %s\n", nowgmt(), strerror(errno));
}
close_relay(data_rw);
return 1;
}
if (debug >= 2) {
printf("%s: TCP write reply, %d/%u bytes\n",
nowgmt(), data_rw->offset + count, data_rw->size);
}
data_rw->offset += count;
if (data_rw->offset < data_rw->size) {
/* Partial write, continue. */
newjob(job_write_reply, now + LONG_TIMEOUT, data_rw);
return 1;
}
if (debug >= 1) tcp_dns_tell(data_rw->w_fd, data_rw->buf);
/* Reply fully send on, go read more replies (or queries). */
data_rw->offset= 0;
data_rw->size= sizeof(u16_t);
newjob(data_rw->w_fd != data_rw->r_fd ? job_read_reply : job_read_query,
now + LONG_TIMEOUT, data_rw);
return 1;
}
#else /* !DO_TCP */
static int job_dummy(void *data, int expired)
{
return 1;
}
#define job_setup_listen job_dummy
#define job_setup_connect job_dummy
#endif /* !DO_TCP */
static void named_probe(ipaddr_t ip)
/* Send a probe to a name daemon, like 'host -r -t ns . <ip>'. */
{
udp_dns_t udp;
# define dlen (offsetof(dns_t, data) + 5)
# define ulen (offsetof(udp_dns_t, dns) + dlen)
/* Send a simple DNS query that all name servers can answer easily:
* "What are the name servers for the root domain?"
*/
udp.dns.hdr.id= new_id(ID_PROBE, my_port, ID_IPSELF);
udp.dns.hdr.qr = 0;
udp.dns.hdr.opcode = 0;
udp.dns.hdr.aa = 0;
udp.dns.hdr.tc = 0;
udp.dns.hdr.rd = 0;
udp.dns.hdr.ra = 0;
udp.dns.hdr.unused = 0;
udp.dns.hdr.ad = 0;
udp.dns.hdr.cd = 0;
udp.dns.hdr.rcode = 0;
udp.dns.hdr.qdcount= HTONS(1);
udp.dns.hdr.ancount= HTONS(0);
udp.dns.hdr.nscount= HTONS(0);
udp.dns.hdr.arcount= HTONS(0);
udp.dns.data[0] = 0; /* Null name. */
pack16(udp.dns.data+1, HTONS(T_NS));
pack16(udp.dns.data+3, HTONS(C_IN));
if (debug >= 1) {
printf("PROBE %s ", inet_ntoa(ip));
dns_tell(0, &udp.dns, dlen);
}
udp.hdr.uih_dst_addr= ip;
udp.hdr.uih_dst_port= named_port;
udp.hdr.uih_ip_opt_len= 0;
udp.hdr.uih_data_len= dlen;
if (write(udp_fd, &udp, ulen) < 0) fatal(udp_device);
#undef dlen
#undef ulen
}
static int job_find_named(void *data, int expired)
/* Look for a real name daemon to answer real DNS queries. */
{
if (!expired) return 0;
if (debug >= 2) printf("%s: Find named\n", nowgmt());
/* New search? */
if (search_ct < 0) {
search_ct= n_nameds;
i_named= -1;
}
if (--search_ct < 0) {
/* Forced end of search (named response!), or end of search with
* nothing found. Search again after a long time.
*/
newjob(job_find_named,
(stale > 0 || i_named > 0) ? now + LONG_TIMEOUT : NEVER, nil);
force_expire(job_setup_connect);
return 1;
}
/* Send a named probe. */
i_named= (i_named+1) % n_nameds;
named_probe(current_named());
/* Schedule the next call. */
newjob(job_find_named, now + SHORT_TIMEOUT, nil);
return 1;
}
static int job_expect_named(void *data, int expired)
/* The real name server is expected to answer by now. */
{
if (!expired) return 0;
if (debug >= 2) printf("%s: Expect named\n", nowgmt());
if (expecting() && !searching()) {
/* No answer yet, start searching. */
start_searching();
force_expire(job_find_named);
}
return 1;
}
static void sig_handler(int sig)
/* A signal forces a search for a real name daemon, etc. */
{
switch (sig) {
case SIGINT:
case SIGTERM: done= 1; break;
case SIGHUP: reinit= 1; break;
case SIGUSR1: debug++; break;
case SIGUSR2: debug= 0; break;
}
}
static void usage(void)
{
fprintf(stderr, "Usage: nonamed [-qs] [-d[level]] [-p port]\n");
exit(1);
}
int main(int argc, char **argv)
{
job_t *job;
nwio_udpopt_t udpopt;
int i;
struct servent *servent;
struct sigaction sa;
FILE *fp;
int quit= 0;
/* Debug output must be line buffered. */
setvbuf(stdout, nil, _IOLBF, 0);
/* DNS service port number? */
if ((servent= getservbyname("domain", nil)) == nil) {
fprintf(stderr, "nonamed: \"domain\": unknown service\n");
exit(1);
}
my_port= servent->s_port;
named_port= servent->s_port;
i= 1;
while (i < argc && argv[i][0] == '-') {
char *opt= argv[i++] + 1, *end;
if (opt[0] == '-' && opt[1] == 0) break;
switch (*opt++) {
case 'd': /* Debug level. */
debug= 1;
if (between('0', *opt, '9')) debug= strtoul(opt, &opt, 10);
break;
case 'p': /* Port to listen to (for testing.) */
if (*opt == 0) {
if (i == argc) usage();
opt= argv[i++];
}
my_port= htons(strtoul(opt, &end, 0));
if (opt == end || *end != 0) usage();
opt= end;
break;
case 's':
single= 1;
break;
case 'q': /* Quit after printing cache contents. */
quit= 1;
break;
case 'L':
localonly= 1;
break;
default:
usage();
}
}
if (i != argc) usage();
if (quit) {
/* Oops, just having a look at the cache. */
debug= 2;
now= time(nil);
n_datamax= -1;
file2cache();
return 0;
}
/* Don't die on broken pipes, reinitialize on hangup, etc. */
sa.sa_handler= SIG_IGN;
sigemptyset(&sa.sa_mask);
sa.sa_flags= 0;
sigaction(SIGPIPE, &sa, nil);
sa.sa_handler= sig_handler;
sigaction(SIGINT, &sa, nil);
sigaction(SIGHUP, &sa, nil);
sigaction(SIGUSR1, &sa, nil);
sigaction(SIGUSR2, &sa, nil);
sigaction(SIGTERM, &sa, nil);
/* TCP and UDP device names. */
if ((tcp_device= getenv("TCP_DEVICE")) == nil) tcp_device= TCP_DEVICE;
if ((udp_device= getenv("UDP_DEVICE")) == nil) udp_device= UDP_DEVICE;
/* Open an UDP channel for incoming DNS queries. */
if ((udp_fd= open(udp_device, O_RDWR)) < 0) fatal(udp_device);
udpopt.nwuo_flags= NWUO_EXCL | NWUO_LP_SET | NWUO_EN_LOC | NWUO_DI_BROAD
| NWUO_RP_ANY | NWUO_RA_ANY | NWUO_RWDATALL | NWUO_DI_IPOPT;
udpopt.nwuo_locport= my_port;
if (ioctl(udp_fd, NWIOSUDPOPT, &udpopt) == -1
|| ioctl(udp_fd, NWIOGUDPOPT, &udpopt) == -1
) {
fatal(udp_device);
}
/* The current time is... */
now= time(nil);
/* Read configuration and data cached by the previous nonamed. */
init_config(udpopt.nwuo_locaddr);
file2cache();
if (!single) {
/* Save process id. */
if ((fp= fopen(PIDFILE, "w")) != nil) {
fprintf(fp, "%u\n", (unsigned) getpid());
fclose(fp);
}
}
/* Jobs that start the ball rolling. */
newjob(job_read_udp, NEVER, nil);
newjob(job_setup_listen, IMMEDIATE, nil);
newjob(job_find_named, IMMEDIATE, nil);
/* Open syslog. */
openlog("nonamed", LOG_PID, LOG_DAEMON);
while (!done) {
/* There is always something in the queue. */
assert(queue != nil);
/* Any expired jobs? */
while (queue->timeout <= now) {
(void) execjob(queue, 1);
assert(queue != nil);
}
/* Check I/O jobs. */
for (job= queue; job != nil; job= job->next) {
if (execjob(job, 0)) break;
}
if (queue->timeout != IMMEDIATE) {
struct timeval tv, *tvp;
if (debug >= 2) printf("%s: I/O wait", nowgmt());
if (queue->timeout != NEVER) {
tv.tv_sec= queue->timeout;
tv.tv_usec= 0;
tvp= &tv;
if (debug >= 2) printf(" (expires %s)\n", timegmt(tv.tv_sec));
} else {
tvp= nil;
if (debug >= 2) fputc('\n', stdout);
}
fflush(stdout);
if (asyn_wait(&asyn, 0, tvp) < 0) {
if (errno != EINTR && errno != EAGAIN) fatal("fwait()");
}
now= time(nil);
}
if (reinit) {
/* A hangup makes us go back to square one. */
reinit= 0;
if (ioctl(udp_fd, NWIOGUDPOPT, &udpopt) == -1) fatal(udp_device);
init_config(udpopt.nwuo_locaddr);
start_searching();
force_expire(job_find_named);
}
}
cache2file();
(void) unlink(PIDFILE);
if (debug >= 2) printf("sbrk(0) = %u\n", (unsigned) sbrk(0));
return 0;
}
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