1 /* 2 * util/edns.c - handle base EDNS options. 3 * 4 * Copyright (c) 2018, NLnet Labs. All rights reserved. 5 * 6 * This software is open source. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * Redistributions of source code must retain the above copyright notice, 13 * this list of conditions and the following disclaimer. 14 * 15 * Redistributions in binary form must reproduce the above copyright notice, 16 * this list of conditions and the following disclaimer in the documentation 17 * and/or other materials provided with the distribution. 18 * 19 * Neither the name of the NLNET LABS nor the names of its contributors may 20 * be used to endorse or promote products derived from this software without 21 * specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 36 /** 37 * \file 38 * 39 * This file contains functions for base EDNS options. 40 */ 41 42 #include "config.h" 43 #include "util/edns.h" 44 #include "util/config_file.h" 45 #include "util/netevent.h" 46 #include "util/regional.h" 47 #include "util/data/msgparse.h" 48 #include "util/data/msgreply.h" 49 50 #include "edns.h" 51 52 static int edns_keepalive(struct edns_data* edns_out, struct edns_data* edns_in, 53 struct comm_point* c, struct regional* region) 54 { 55 if(c->type == comm_udp) 56 return 1; 57 58 /* To respond with a Keepalive option, the client connection 59 * must have received one message with a TCP Keepalive EDNS option, 60 * and that option must have 0 length data. Subsequent messages 61 * sent on that connection will have a TCP Keepalive option. 62 */ 63 if(c->tcp_keepalive || 64 edns_opt_list_find(edns_in->opt_list, LDNS_EDNS_KEEPALIVE)) { 65 int keepalive = c->tcp_timeout_msec / 100; 66 uint8_t data[2]; 67 data[0] = (uint8_t)((keepalive >> 8) & 0xff); 68 data[1] = (uint8_t)(keepalive & 0xff); 69 if(!edns_opt_list_append(&edns_out->opt_list, LDNS_EDNS_KEEPALIVE, 70 sizeof(data), data, region)) 71 return 0; 72 c->tcp_keepalive = 1; 73 } 74 return 1; 75 } 76 77 int apply_edns_options(struct edns_data* edns_out, struct edns_data* edns_in, 78 struct config_file* cfg, struct comm_point* c, struct regional* region) 79 { 80 if(cfg->do_tcp_keepalive && 81 !edns_keepalive(edns_out, edns_in, c, region)) 82 return 0; 83 84 return 1; 85 } 86