diff options
| -rw-r--r-- | include/libbb.h | 6 | ||||
| -rw-r--r-- | libbb/udp_io.c | 5 | ||||
| -rw-r--r-- | networking/dnsd.c | 117 |
3 files changed, 65 insertions, 63 deletions
diff --git a/include/libbb.h b/include/libbb.h index ee1ef518e..df8b0ecdb 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -476,10 +476,12 @@ struct hostent *xgethostbyname(const char *name); void socket_want_pktinfo(int fd); ssize_t send_to_from(int fd, void *buf, size_t len, int flags, - const struct sockaddr *from, const struct sockaddr *to, + const struct sockaddr *to, + const struct sockaddr *from, socklen_t tolen); ssize_t recv_from_to(int fd, void *buf, size_t len, int flags, - struct sockaddr *from, struct sockaddr *to, + struct sockaddr *from, + struct sockaddr *to, socklen_t sa_size); char *xstrdup(const char *s); diff --git a/libbb/udp_io.c b/libbb/udp_io.c index 2f02a138b..e968ecb66 100644 --- a/libbb/udp_io.c +++ b/libbb/udp_io.c @@ -25,10 +25,10 @@ socket_want_pktinfo(int fd) } -#ifdef UNUSED ssize_t send_to_from(int fd, void *buf, size_t len, int flags, - const struct sockaddr *from, const struct sockaddr *to, + const struct sockaddr *to, + const struct sockaddr *from, socklen_t tolen) { #ifndef IP_PKTINFO @@ -92,7 +92,6 @@ send_to_from(int fd, void *buf, size_t len, int flags, return sendmsg(fd, &msg, flags); #endif } -#endif /* UNUSED */ /* NB: this will never set port# in 'to'! * _Only_ IP/IPv6 address part of 'to' is _maybe_ modified. diff --git a/networking/dnsd.c b/networking/dnsd.c index b269bc52a..cb62d2081 100644 --- a/networking/dnsd.c +++ b/networking/dnsd.c @@ -36,7 +36,7 @@ enum { ttl(4B) + rlen(2B) + r (MAX_NAME_LEN =21B) + 2*querystring (2 MAX_NAME_LEN= 42B), all together 90 Byte */ - MAX_PACK_LEN = 512 + 1, + MAX_PACK_LEN = 512, DEFAULT_TTL = 30, // increase this when not testing? @@ -44,12 +44,6 @@ enum { REQ_PTR = 12 }; -struct dns_repl { // resource record, add 0 or 1 to accepted dns_msg in resp - uint16_t rlen; - uint8_t *r; // resource - uint16_t flags; -}; - struct dns_head { // the message from client and first part of response mag uint16_t id; uint16_t flags; @@ -218,20 +212,20 @@ static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs) return -1; } - /* * Decode message and generate answer */ -static int process_packet(uint8_t * buf) +static int process_packet(uint8_t *buf) { + uint8_t answstr[MAX_NAME_LEN + 1]; struct dns_head *head; struct dns_prop *qprop; - struct dns_repl outr; - void *next, *from, *answb; - - uint8_t answstr[MAX_NAME_LEN + 1]; - int lookup_result, type, len, packet_len; + uint8_t *from, *answb; + uint16_t outr_rlen; + uint16_t outr_flags; uint16_t flags; + int lookup_result, type, packet_len; + int querystr_len; answstr[0] = '\0'; @@ -247,11 +241,12 @@ static int process_packet(uint8_t * buf) } from = (void *)&head[1]; // start of query string - next = answb = from + strlen((char *)from) + 1 + sizeof(struct dns_prop); // where to append answer block +//FIXME: strlen of untrusted data??! + querystr_len = strlen((char *)from) + 1 + sizeof(struct dns_prop); + answb = from + querystr_len; // where to append answer block - outr.rlen = 0; // may change later - outr.r = NULL; - outr.flags = 0; + outr_rlen = 0; + outr_flags = 0; qprop = (struct dns_prop *)(answb - 4); type = ntohs(qprop->type); @@ -262,7 +257,7 @@ static int process_packet(uint8_t * buf) } if (ntohs(qprop->class) != 1 /* class INET */ ) { - outr.flags = 4; /* not supported */ + outr_flags = 4; /* not supported */ goto empty_packet; } /* we only support standard queries */ @@ -272,49 +267,50 @@ static int process_packet(uint8_t * buf) // We have a standard query bb_info_msg("%s", (char *)from); - lookup_result = table_lookup(type, answstr, (uint8_t*)from); + lookup_result = table_lookup(type, answstr, from); if (lookup_result != 0) { - outr.flags = 3 | 0x0400; //name do not exist and auth + outr_flags = 3 | 0x0400; // name do not exist and auth goto empty_packet; } if (type == REQ_A) { // return an address - struct in_addr a; - if (!inet_aton((char*)answstr, &a)) {//dotted dec to long conv - outr.flags = 1; /* Frmt err */ + struct in_addr a; // NB! its "struct { unsigned __long__ s_addr; }" + uint32_t v32; + if (!inet_aton((char*)answstr, &a)) { //dotted dec to long conv + outr_flags = 1; /* Frmt err */ goto empty_packet; } - memcpy(answstr, &a.s_addr, 4); // save before a disappears - outr.rlen = 4; // uint32_t IP + v32 = a.s_addr; /* in case long != int */ + memcpy(answstr, &v32, 4); + outr_rlen = 4; // uint32_t IP } else - outr.rlen = strlen((char *)answstr) + 1; // a host name - outr.r = answstr; // 32 bit ip or a host name - outr.flags |= 0x0400; /* authority-bit */ + outr_rlen = strlen((char *)answstr) + 1; // a host name + outr_flags |= 0x0400; /* authority-bit */ // we have an answer head->nansw = htons(1); // copy query block to answer block - len = answb - from; - memcpy(answb, from, len); - next += len; + memcpy(answb, from, querystr_len); + answb += querystr_len; // and append answer rr - *(uint32_t *) next = htonl(ttl); - next += 4; - *(uint16_t *) next = htons(outr.rlen); - next += 2; - memcpy(next, (void *)answstr, outr.rlen); - next += outr.rlen; +// FIXME: unaligned accesses?? + *(uint32_t *) answb = htonl(ttl); + answb += 4; + *(uint16_t *) answb = htons(outr_rlen); + answb += 2; + memcpy(answb, answstr, outr_rlen); + answb += outr_rlen; empty_packet: flags = ntohs(head->flags); // clear rcode and RA, set responsebit and our new flags - flags |= (outr.flags & 0xff80) | 0x8000; + flags |= (outr_flags & 0xff80) | 0x8000; head->flags = htons(flags); - head->nauth = head->nadd = htons(0); + head->nauth = head->nadd = 0; head->nquer = htons(1); - packet_len = (uint8_t *)next - buf; + packet_len = answb - buf; return packet_len; } @@ -333,10 +329,13 @@ int dnsd_main(int argc ATTRIBUTE_UNUSED, char **argv) { const char *listen_interface = "0.0.0.0"; char *sttl, *sport; - len_and_sockaddr *lsa; + len_and_sockaddr *lsa, *from, *to; + unsigned lsa_size; int udps; uint16_t port = 53; - uint8_t buf[MAX_PACK_LEN]; + /* Paranoid sizing: querystring x2 + ttl + outr_rlen + answstr */ + /* I'd rather see process_packet() fixed instead... */ + uint8_t buf[MAX_PACK_LEN * 2 + 4 + 2 + (MAX_NAME_LEN+1)]; getopt32(argv, "i:c:t:p:dv", &listen_interface, &fileconf, &sttl, &sport); //if (option_mask32 & 0x1) // -i @@ -375,32 +374,34 @@ int dnsd_main(int argc ATTRIBUTE_UNUSED, char **argv) lsa = xdotted2sockaddr(listen_interface, port); udps = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0); xbind(udps, &lsa->u.sa, lsa->len); - /* xlisten(udps, 50); - ?!! DGRAM sockets are never listened on I think? */ + socket_want_pktinfo(udps); /* needed for recv_from_to to work */ + lsa_size = LSA_LEN_SIZE + lsa->len; + from = xzalloc(lsa_size); + to = xzalloc(lsa_size); + bb_info_msg("Accepting UDP packets on %s", xmalloc_sockaddr2dotted(&lsa->u.sa)); while (1) { int r; - socklen_t fromlen = lsa->len; -// FIXME: need to get *DEST* address (to which of our addresses -// this query was directed), and reply from the same address. -// Or else we can exhibit usual UDP ugliness: -// [ip1.multihomed.ip2] <= query to ip1 <= peer -// [ip1.multihomed.ip2] => reply from ip2 => peer (confused) - -// TODO: recv_from_to - - r = recvfrom(udps, buf, sizeof(buf), 0, &lsa->u.sa, &fromlen); - if (OPT_verbose) - bb_info_msg("Got UDP packet"); - if (r < 12 || r > 512) { + /* Try to get *DEST* address (to which of our addresses + * this query was directed), and reply from the same address. + * Or else we can exhibit usual UDP ugliness: + * [ip1.multihomed.ip2] <= query to ip1 <= peer + * [ip1.multihomed.ip2] => reply from ip2 => peer (confused) */ + memcpy(to, lsa, lsa_size); + r = recv_from_to(udps, buf, MAX_PACK_LEN + 1, 0, &from->u.sa, &to->u.sa, lsa->len); + if (r < 12 || r > MAX_PACK_LEN) { bb_error_msg("invalid packet size"); continue; } + if (OPT_verbose) + bb_info_msg("Got UDP packet"); + buf[r] = '\0'; /* paranoia */ r = process_packet(buf); if (r <= 0) continue; - sendto(udps, buf, r, 0, &lsa->u.sa, fromlen); + send_to_from(udps, buf, r, 0, &to->u.sa, &from->u.sa, lsa->len); } return 0; } |