diff options
Diffstat (limited to 'llmnr.c')
| -rw-r--r-- | llmnr.c | 58 |
1 files changed, 15 insertions, 43 deletions
@@ -76,20 +76,16 @@ static void llmnr_respond(unsigned int ifindex, const struct llmnr_hdr *hdr, struct pkt *p; struct llmnr_hdr *r; - if ((query_len - name_len - 2) < 4) { - log_err("Invalid query format\n"); + /* 4 bytes expected for QTYPE and QCLASS */ + if ((query_len - name_len - 2) < (sizeof(qtype) + sizeof(qclass))) return; - } qtype = ntohs(*((uint16_t *)query_name_end)); qclass = ntohs(*((uint16_t *)query_name_end + 1)); - log_info("query len: %zu type %04x class %04x\n", query_len - name_len - 2, qtype, qclass); - - if (qclass != LLMNR_QCLASS_IN) { - log_dbg("Unsupported QCLASS: %04x\n", qclass); + /* Ony IN queries supported */ + if (qclass != LLMNR_QCLASS_IN) return; - } switch (qtype) { case LLMNR_QTYPE_A: @@ -102,7 +98,6 @@ static void llmnr_respond(unsigned int ifindex, const struct llmnr_hdr *hdr, family = AF_UNSPEC; break; default: - log_dbg("Unsupported QTYPE: %04x\n", qtype); return; } @@ -144,10 +139,8 @@ static void llmnr_respond(unsigned int ifindex, const struct llmnr_hdr *hdr, addr = &sin6->sin6_addr; addr_size = sizeof(sin6->sin6_addr); type = LLMNR_TYPE_AAAA; - } else { - /* skip */ + } else continue; - } /* * NAME @@ -168,9 +161,8 @@ static void llmnr_respond(unsigned int ifindex, const struct llmnr_hdr *hdr, memcpy(pkt_put(p, addr_size), addr, addr_size); } - if (sendto(sock, p->data, pkt_len(p), 0, sa, sizeof(struct sockaddr_in)) < 0) { + if (sendto(sock, p->data, pkt_len(p), 0, sa, sizeof(struct sockaddr_in)) < 0) log_err("Failed to send response: %s\n", strerror(errno)); - } pkt_free(p); } @@ -179,53 +171,33 @@ static void llmnr_packet_process(unsigned int ifindex, const uint8_t *pktbuf, si int sock, const struct sockaddr *sa) { const struct llmnr_hdr *hdr = (const struct llmnr_hdr *)pktbuf; - uint16_t id, flags, qdcount; - char rhost[INET6_ADDRSTRLEN]; - char ifname[IF_NAMESIZE]; - const void *addr = NULL; + uint16_t flags, qdcount; const uint8_t *query; size_t query_len; uint8_t name_len; - if (sa->sa_family == AF_INET) - addr = &((const struct sockaddr_in *)sa)->sin_addr; - else if (sa->sa_family == AF_INET6) - addr = &((const struct sockaddr_in6 *)sa)->sin6_addr; - - if (!addr || !inet_ntop(sa->sa_family, addr, rhost, sizeof(rhost))) - strncpy(rhost, "<unknown>", sizeof(rhost) - 1); - - if (len < sizeof(struct llmnr_hdr)) { - log_warn("Short packet received (%zu bytes) from host %s\n", len, rhost); + /* Query too short? */ + if (len < sizeof(struct llmnr_hdr)) return; - } - id = ntohs(hdr->id); flags = ntohs(hdr->flags); qdcount = ntohs(hdr->qdcount); - log_info("LLMNR packet (%zu bytes) from host %s on interface %s\n", len, - rhost, if_indextoname(ifindex, ifname)); - log_info("[ id 0x%04x flags %04x qdcount %04x ]\n", id, flags, qdcount); - + /* Query invalid as per RFC 4795, section 2.1.1? */ if (((flags & (LLMNR_F_QR | LLMNR_F_OPCODE)) != 0) || - qdcount != 1 || hdr->ancount != 0 || hdr->nscount != 0) { - /* silently discard invalid queries */ + qdcount != 1 || hdr->ancount != 0 || hdr->nscount != 0) return; - } query = pktbuf + sizeof(struct llmnr_hdr); query_len = len - sizeof(struct llmnr_hdr); name_len = query[0]; - if (name_len == 0 || name_len >= query_len || query[1 + name_len] != 0) { - log_warn("Invalid query format received from host %s\n", rhost); + /* Invalid name in query? */ + if (name_len == 0 || name_len >= query_len || query[1 + name_len] != 0) return; - } - log_info("[ query %s (%zu bytes) ]\n", (char*)query + 1, query_len); - if (query_len > name_len && llmnr_name_matches(query)) { + /* Authoritative? */ + if (llmnr_name_matches(query)) llmnr_respond(ifindex, hdr, query, query_len, sock, sa); - } } int llmnr_run(const char *hostname, uint16_t port) |