/* 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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. */ dns_hdr_t hdr; /* DNS header. */ u8_t data[PACKETSZ - sizeof(dns_hdr_t)]; /* 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(dns_hdr_t)) return; printf("%*s", indent, ""); printf("DNS %s:", (dp->hdr.dh_flag1 & DHF_QR) ? "reply" : "query"); r= dp->hdr.dh_flag2 & DHF_RCODE; printf(" %s", r < arraysize(rcodes) ? rcodes[r] : itoa("ERR_%lu", r)); if (dp->hdr.dh_flag1 & DHF_AA) printf(" AA"); if (dp->hdr.dh_flag1 & DHF_TC) printf(" TC"); if (dp->hdr.dh_flag1 & DHF_RD) printf(" RD"); if (dp->hdr.dh_flag2 & DHF_RA) printf(" RA"); #ifdef DHF_AD if (dp->hdr.dh_flag2 & DHF_AD) printf(" AD"); if (dp->hdr.dh_flag2 & DHF_CD) printf(" CD"); #endif fputc('\n', stdout); count[0]= ntohs(dp->hdr.dh_qdcount); count[1]= ntohs(dp->hdr.dh_ancount); count[2]= ntohs(dp->hdr.dh_nscount); count[3]= ntohs(dp->hdr.dh_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(dns_hdr_t)) return 0; rcode= dp->hdr.dh_flag2 & DHF_RCODE; count[0]= ntohs(dp->hdr.dh_qdcount); count[1]= ntohs(dp->hdr.dh_ancount); count[2]= ntohs(dp->hdr.dh_nscount); count[3]= ntohs(dp->hdr.dh_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= HTONL(LOCALHOST); static char *localaddrlist[]= { (char *) &localaddr, nil }; if (single) return 0; /* Assume we can answer. */ dns.hdr.dh_flag1= DHF_QR | DHF_AA; dns.hdr.dh_flag2= DHF_RA; dns.hdr.dh_qdcount= HTONS(1); ancount= 0; dns.hdr.dh_nscount= HTONS(0); dns.hdr.dh_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 { switch (type) { case HTONS(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 HTONS(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 HTONS(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.dh_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.dh_flag1= DHF_QR | DHF_AA; dns.hdr.dh_flag2= DHF_RA; dns.hdr.dh_qdcount= HTONS(1); dns.hdr.dh_ancount= HTONS(1); dns.hdr.dh_nscount= HTONS(0); dns.hdr.dh_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.dh_flag1 & (DHF_RD | DHF_TC)) != DHF_RD) return; if (dp->hdr.dh_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.dh_id; rd= dp->hdr.dh_flag1 & DHF_RD; if (r == -1) { /* Malformed query, reply "FORMERR". */ dp->hdr.dh_flag1 &= ~(DHF_TC); dp->hdr.dh_flag1 |= DHF_QR | DHF_AA; dp->hdr.dh_flag2 &= ~(DHF_UNUSED | DHF_RCODE); dp->hdr.dh_flag2 |= DHF_RA | 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.dh_flag1 &= ~DHF_AA; (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.dh_flag1 &= ~(DHF_TC); dp->hdr.dh_flag1 |= DHF_QR | DHF_AA; dp->hdr.dh_flag2 &= ~(DHF_UNUSED | DHF_RCODE); dp->hdr.dh_flag2 |= DHF_RA | NXDOMAIN; } else if (!rd) { /* "Recursion Desired" is off, so don't bother to relay. */ dp->hdr.dh_flag1 &= ~(DHF_TC); dp->hdr.dh_flag1 |= DHF_QR; dp->hdr.dh_flag2 &= ~(DHF_UNUSED | DHF_RCODE); dp->hdr.dh_flag2 |= DHF_RA | NOERROR; } else { /* Caller needs to consult with a real name daemon. */ return 0; } /* Copy ID and RD back to answer. */ dp->hdr.dh_id= id; dp->hdr.dh_flag1 &= ~DHF_RD; dp->hdr.dh_flag1 |= 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.dh_id= new_id(ID_REFRESH, my_port, ID_IPSELF); udp.dns.hdr.dh_flag1= DHF_RD; udp.dns.hdr.dh_flag2= 0; udp.dns.hdr.dh_qdcount= HTONS(1); udp.dns.hdr.dh_ancount= HTONS(0); udp.dns.hdr.dh_nscount= HTONS(0); udp.dns.hdr.dh_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(dns_hdr_t))) 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.dh_flag1 & DHF_QR) { /* This is a remote named reply, not a query. */ /* Response to a query previously relayed? */ if (!old_id(udp.dns.hdr.dh_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.dh_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.dh_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.dh_id= new_id(udp.dns.hdr.dh_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 . '. */ { 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.dh_id= new_id(ID_PROBE, my_port, ID_IPSELF); udp.dns.hdr.dh_flag1= 0; udp.dns.hdr.dh_flag2= 0; udp.dns.hdr.dh_qdcount= HTONS(1); udp.dns.hdr.dh_ancount= HTONS(0); udp.dns.hdr.dh_nscount= HTONS(0); udp.dns.hdr.dh_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; }