diff options
| -rw-r--r-- | llmnr.c | 176 |
1 files changed, 89 insertions, 87 deletions
@@ -67,6 +67,15 @@ static void llmnr_respond(unsigned int ifindex, const struct llmnr_hdr *hdr, uint8_t name_len = query[0]; /* skip name length & additional '\0' byte */ const uint8_t *query_name_end = query + name_len + 2; + size_t i, n, response_len; + unsigned char family = AF_UNSPEC; + /* + * arbitrary restriction to 16 addresses per interface for the + * sake of a simple, atomic interface + */ + struct sockaddr_storage addrs[16]; + struct pkt *p; + struct llmnr_hdr *r; if ((query_len - name_len - 2) < 4) { log_err("Invalid query format\n"); @@ -78,101 +87,94 @@ static void llmnr_respond(unsigned int ifindex, const struct llmnr_hdr *hdr, log_info("query len: %zu type %04x class %04x\n", query_len - name_len - 2, qtype, qclass); - if (qclass == LLMNR_QCLASS_IN) { - size_t i, n, response_len; - unsigned char family = AF_UNSPEC; - /* - * arbitrary restriction to 16 addresses per interface for the - * sake of a simple, atomic interface - */ - struct sockaddr_storage addrs[16]; - struct pkt *p; - struct llmnr_hdr *r; - - switch (qtype) { - case LLMNR_QTYPE_A: - family = AF_INET; - break; - case LLMNR_QTYPE_AAAA: - family = AF_INET6; - break; - case LLMNR_QTYPE_ANY: - family = AF_UNSPEC; - break; - default: - log_err("Unsupported QTYPE: %04x\n", qtype); - return; - } + if (qclass != LLMNR_QCLASS_IN) { + log_dbg("Unsupported QCLASS: %04x\n", qclass); + return; + } - n = iface_addr_lookup(ifindex, family, addrs, ARRAY_SIZE(addrs)); + switch (qtype) { + case LLMNR_QTYPE_A: + family = AF_INET; + break; + case LLMNR_QTYPE_AAAA: + family = AF_INET6; + break; + case LLMNR_QTYPE_ANY: + family = AF_UNSPEC; + break; + default: + log_dbg("Unsupported QTYPE: %04x\n", qtype); + return; + } - log_info("Responding with %zu addresses\n", n); + n = iface_addr_lookup(ifindex, family, addrs, ARRAY_SIZE(addrs)); + + log_info("Responding with %zu addresses\n", n); + + /* + * This is the max response length (i.e. using all IPv6 addresses and + * not message compression). We might not use all of it. + */ + response_len = n * (1 + name_len + 1 + 2 + 2 + 4 + 2 + sizeof(struct in6_addr)); + p = pkt_alloc(sizeof(*hdr) + query_len + response_len); + + /* fill the LLMNR header */ + r = (struct llmnr_hdr *)pkt_put(p, sizeof(*r)); + r->id = hdr->id; + /* response flag */ + r->flags = htons(LLMNR_F_QR); + r->qdcount = hdr->qdcount; + r->ancount = htons(n); + r->nscount = 0; + r->arcount = 0; + + /* copy the original question */ + memcpy(pkt_put(p, query_len), query, query_len); + + /* append an RR for each address */ + for (i = 0; i < n; i++) { + void *addr; + size_t addr_size; + + if (addrs[i].ss_family == AF_INET) { + struct sockaddr_in *sin = (struct sockaddr_in *)&addrs[i]; + addr = &sin->sin_addr; + addr_size = sizeof(sin->sin_addr); + } else if (addrs[i].ss_family == AF_INET6) { + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&addrs[i]; + addr = &sin6->sin6_addr; + addr_size = sizeof(sin6->sin6_addr); + } else { + /* skip */ + continue; + } /* - * This is the max response length (i.e. using all IPv6 - * addresses). We might not use all of it. + * NAME + * + * TODO: Implement message compression (RFC 1035, + * section 4.1.3) */ - response_len = n * (1 + name_len + 1 + 2 + 2 + 4 + 2 + sizeof(struct in6_addr)); - p = pkt_alloc(sizeof(*hdr) + query_len + response_len); - - /* fill the LLMNR header */ - r = (struct llmnr_hdr *)pkt_put(p, sizeof(*r)); - r->id = hdr->id; - /* response flag */ - r->flags = htons(LLMNR_F_QR); - r->qdcount = hdr->qdcount; - r->ancount = htons(n); - r->nscount = 0; - r->arcount = 0; - - /* copy the original question */ - memcpy(pkt_put(p, query_len), query, query_len); - - /* append an RR for each address */ - for (i = 0; i < n; i++) { - void *addr; - size_t addr_size; - - if (addrs[i].ss_family == AF_INET) { - struct sockaddr_in *sin = (struct sockaddr_in *)&addrs[i]; - addr = &sin->sin_addr; - addr_size = sizeof(sin->sin_addr); - } else if (addrs[i].ss_family == AF_INET6) { - struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&addrs[i]; - addr = &sin6->sin6_addr; - addr_size = sizeof(sin6->sin6_addr); - } else { - /* skip */ - continue; - } - - /* - * NAME - * - * TODO: Implement message compression (RFC 1035, - * section 4.1.3) - */ - memcpy(pkt_put(p, llmnr_hostname[0]), llmnr_hostname, llmnr_hostname[0] + 2); - /* TYPE */ - pkt_put_u16(p, qtype); - /* CLASS */ - pkt_put_u16(p, LLMNR_CLASS_IN); - /* TTL */ - pkt_put_u32(p, LLMNR_TTL_DEFAULT); - /* RDLENGTH */ - pkt_put_u16(p, addr_size); - /* RDATA */ - memcpy(pkt_put(p, addr_size), addr, addr_size); - } - - log_info("Response packet length: %zu\n", pkt_len(p)); + memcpy(pkt_put(p, llmnr_hostname[0]), llmnr_hostname, llmnr_hostname[0] + 2); + /* TYPE */ + pkt_put_u16(p, qtype); + /* CLASS */ + pkt_put_u16(p, LLMNR_CLASS_IN); + /* TTL */ + pkt_put_u32(p, LLMNR_TTL_DEFAULT); + /* RDLENGTH */ + pkt_put_u16(p, addr_size); + /* RDATA */ + memcpy(pkt_put(p, addr_size), addr, addr_size); + } - 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)); - } + log_info("Response packet length: %zu\n", pkt_len(p)); - pkt_free(p); + 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); } static void llmnr_packet_process(unsigned int ifindex, const uint8_t *pktbuf, size_t len, |