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842 lines
25 KiB
C
842 lines
25 KiB
C
/*
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* util/data/msgencode.c - Encode DNS messages, queries and replies.
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*
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* Copyright (c) 2007, NLnet Labs. All rights reserved.
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*
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* This software is open source.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* Neither the name of the NLNET LABS nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
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* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/**
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* \file
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*
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* This file contains a routines to encode DNS messages.
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*/
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#include "config.h"
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#include "util/data/msgencode.h"
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#include "util/data/msgreply.h"
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#include "util/data/msgparse.h"
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#include "util/data/dname.h"
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#include "util/log.h"
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#include "util/regional.h"
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#include "util/net_help.h"
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#include "ldns/sbuffer.h"
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/** return code that means the function ran out of memory. negative so it does
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* not conflict with DNS rcodes. */
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#define RETVAL_OUTMEM -2
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/** return code that means the data did not fit (completely) in the packet */
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#define RETVAL_TRUNC -4
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/** return code that means all is peachy keen. Equal to DNS rcode NOERROR */
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#define RETVAL_OK 0
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/**
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* Data structure to help domain name compression in outgoing messages.
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* A tree of dnames and their offsets in the packet is kept.
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* It is kept sorted, not canonical, but by label at least, so that after
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* a lookup of a name you know its closest match, and the parent from that
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* closest match. These are possible compression targets.
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*
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* It is a binary tree, not a rbtree or balanced tree, as the effort
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* of keeping it balanced probably outweighs usefulness (given typical
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* DNS packet size).
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*/
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struct compress_tree_node {
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/** left node in tree, all smaller to this */
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struct compress_tree_node* left;
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/** right node in tree, all larger than this */
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struct compress_tree_node* right;
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/** the parent node - not for tree, but zone parent. One less label */
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struct compress_tree_node* parent;
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/** the domain name for this node. Pointer to uncompressed memory. */
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uint8_t* dname;
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/** number of labels in domain name, kept to help compare func. */
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int labs;
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/** offset in packet that points to this dname */
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size_t offset;
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};
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/**
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* Find domain name in tree, returns exact and closest match.
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* @param tree: root of tree.
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* @param dname: pointer to uncompressed dname.
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* @param labs: number of labels in domain name.
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* @param match: closest or exact match.
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* guaranteed to be smaller or equal to the sought dname.
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* can be null if the tree is empty.
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* @param matchlabels: number of labels that match with closest match.
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* can be zero is there is no match.
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* @param insertpt: insert location for dname, if not found.
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* @return: 0 if no exact match.
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*/
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static int
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compress_tree_search(struct compress_tree_node** tree, uint8_t* dname,
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int labs, struct compress_tree_node** match, int* matchlabels,
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struct compress_tree_node*** insertpt)
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{
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int c, n, closen=0;
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struct compress_tree_node* p = *tree;
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struct compress_tree_node* close = 0;
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struct compress_tree_node** prev = tree;
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while(p) {
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if((c = dname_lab_cmp(dname, labs, p->dname, p->labs, &n))
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== 0) {
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*matchlabels = n;
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*match = p;
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return 1;
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}
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if(c<0) {
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prev = &p->left;
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p = p->left;
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} else {
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closen = n;
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close = p; /* p->dname is smaller than dname */
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prev = &p->right;
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p = p->right;
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}
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}
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*insertpt = prev;
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*matchlabels = closen;
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*match = close;
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return 0;
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}
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/**
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* Lookup a domain name in compression tree.
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* @param tree: root of tree (not the node with '.').
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* @param dname: pointer to uncompressed dname.
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* @param labs: number of labels in domain name.
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* @param insertpt: insert location for dname, if not found.
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* @return: 0 if not found or compress treenode with best compression.
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*/
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static struct compress_tree_node*
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compress_tree_lookup(struct compress_tree_node** tree, uint8_t* dname,
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int labs, struct compress_tree_node*** insertpt)
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{
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struct compress_tree_node* p;
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int m;
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if(labs <= 1)
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return 0; /* do not compress root node */
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if(compress_tree_search(tree, dname, labs, &p, &m, insertpt)) {
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/* exact match */
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return p;
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}
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/* return some ancestor of p that compresses well. */
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if(m>1) {
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/* www.example.com. (labs=4) matched foo.example.com.(labs=4)
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* then matchcount = 3. need to go up. */
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while(p && p->labs > m)
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p = p->parent;
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return p;
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}
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return 0;
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}
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/**
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* Create node for domain name compression tree.
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* @param dname: pointer to uncompressed dname (stored in tree).
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* @param labs: number of labels in dname.
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* @param offset: offset into packet for dname.
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* @param region: how to allocate memory for new node.
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* @return new node or 0 on malloc failure.
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*/
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static struct compress_tree_node*
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compress_tree_newnode(uint8_t* dname, int labs, size_t offset,
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struct regional* region)
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{
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struct compress_tree_node* n = (struct compress_tree_node*)
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regional_alloc(region, sizeof(struct compress_tree_node));
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if(!n) return 0;
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n->left = 0;
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n->right = 0;
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n->parent = 0;
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n->dname = dname;
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n->labs = labs;
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n->offset = offset;
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return n;
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}
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/**
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* Store domain name and ancestors into compression tree.
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* @param dname: pointer to uncompressed dname (stored in tree).
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* @param labs: number of labels in dname.
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* @param offset: offset into packet for dname.
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* @param region: how to allocate memory for new node.
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* @param closest: match from previous lookup, used to compress dname.
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* may be NULL if no previous match.
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* if the tree has an ancestor of dname already, this must be it.
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* @param insertpt: where to insert the dname in tree.
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* @return: 0 on memory error.
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*/
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static int
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compress_tree_store(uint8_t* dname, int labs, size_t offset,
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struct regional* region, struct compress_tree_node* closest,
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struct compress_tree_node** insertpt)
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{
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uint8_t lablen;
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struct compress_tree_node* newnode;
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struct compress_tree_node* prevnode = NULL;
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int uplabs = labs-1; /* does not store root in tree */
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if(closest) uplabs = labs - closest->labs;
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log_assert(uplabs >= 0);
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/* algorithms builds up a vine of dname-labels to hang into tree */
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while(uplabs--) {
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if(offset > PTR_MAX_OFFSET) {
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/* insertion failed, drop vine */
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return 1; /* compression pointer no longer useful */
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}
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if(!(newnode = compress_tree_newnode(dname, labs, offset,
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region))) {
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/* insertion failed, drop vine */
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return 0;
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}
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if(prevnode) {
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/* chain nodes together, last one has one label more,
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* so is larger than newnode, thus goes right. */
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newnode->right = prevnode;
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prevnode->parent = newnode;
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}
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/* next label */
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lablen = *dname++;
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dname += lablen;
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offset += lablen+1;
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prevnode = newnode;
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labs--;
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}
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/* if we have a vine, hang the vine into the tree */
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if(prevnode) {
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*insertpt = prevnode;
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prevnode->parent = closest;
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}
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return 1;
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}
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/** compress a domain name */
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static int
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write_compressed_dname(sldns_buffer* pkt, uint8_t* dname, int labs,
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struct compress_tree_node* p)
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{
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/* compress it */
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int labcopy = labs - p->labs;
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uint8_t lablen;
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uint16_t ptr;
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if(labs == 1) {
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/* write root label */
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if(sldns_buffer_remaining(pkt) < 1)
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return 0;
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sldns_buffer_write_u8(pkt, 0);
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return 1;
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}
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/* copy the first couple of labels */
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while(labcopy--) {
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lablen = *dname++;
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if(sldns_buffer_remaining(pkt) < (size_t)lablen+1)
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return 0;
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sldns_buffer_write_u8(pkt, lablen);
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sldns_buffer_write(pkt, dname, lablen);
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dname += lablen;
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}
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/* insert compression ptr */
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if(sldns_buffer_remaining(pkt) < 2)
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return 0;
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ptr = PTR_CREATE(p->offset);
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sldns_buffer_write_u16(pkt, ptr);
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return 1;
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}
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/** compress owner name of RR, return RETVAL_OUTMEM RETVAL_TRUNC */
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static int
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compress_owner(struct ub_packed_rrset_key* key, sldns_buffer* pkt,
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struct regional* region, struct compress_tree_node** tree,
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size_t owner_pos, uint16_t* owner_ptr, int owner_labs)
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{
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struct compress_tree_node* p;
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struct compress_tree_node** insertpt;
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if(!*owner_ptr) {
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/* compress first time dname */
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if((p = compress_tree_lookup(tree, key->rk.dname,
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owner_labs, &insertpt))) {
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if(p->labs == owner_labs)
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/* avoid ptr chains, since some software is
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* not capable of decoding ptr after a ptr. */
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*owner_ptr = htons(PTR_CREATE(p->offset));
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if(!write_compressed_dname(pkt, key->rk.dname,
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owner_labs, p))
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return RETVAL_TRUNC;
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/* check if typeclass+4 ttl + rdatalen is available */
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if(sldns_buffer_remaining(pkt) < 4+4+2)
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return RETVAL_TRUNC;
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} else {
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/* no compress */
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if(sldns_buffer_remaining(pkt) < key->rk.dname_len+4+4+2)
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return RETVAL_TRUNC;
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sldns_buffer_write(pkt, key->rk.dname,
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key->rk.dname_len);
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if(owner_pos <= PTR_MAX_OFFSET)
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*owner_ptr = htons(PTR_CREATE(owner_pos));
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}
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if(!compress_tree_store(key->rk.dname, owner_labs,
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owner_pos, region, p, insertpt))
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return RETVAL_OUTMEM;
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} else {
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/* always compress 2nd-further RRs in RRset */
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if(owner_labs == 1) {
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if(sldns_buffer_remaining(pkt) < 1+4+4+2)
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return RETVAL_TRUNC;
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sldns_buffer_write_u8(pkt, 0);
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} else {
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if(sldns_buffer_remaining(pkt) < 2+4+4+2)
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return RETVAL_TRUNC;
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sldns_buffer_write(pkt, owner_ptr, 2);
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}
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}
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return RETVAL_OK;
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}
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/** compress any domain name to the packet, return RETVAL_* */
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static int
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compress_any_dname(uint8_t* dname, sldns_buffer* pkt, int labs,
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struct regional* region, struct compress_tree_node** tree)
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{
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struct compress_tree_node* p;
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struct compress_tree_node** insertpt = NULL;
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size_t pos = sldns_buffer_position(pkt);
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if((p = compress_tree_lookup(tree, dname, labs, &insertpt))) {
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if(!write_compressed_dname(pkt, dname, labs, p))
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return RETVAL_TRUNC;
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} else {
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if(!dname_buffer_write(pkt, dname))
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return RETVAL_TRUNC;
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}
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if(!compress_tree_store(dname, labs, pos, region, p, insertpt))
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return RETVAL_OUTMEM;
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return RETVAL_OK;
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}
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/** return true if type needs domain name compression in rdata */
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static const sldns_rr_descriptor*
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type_rdata_compressable(struct ub_packed_rrset_key* key)
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{
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uint16_t t = ntohs(key->rk.type);
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if(sldns_rr_descript(t) &&
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sldns_rr_descript(t)->_compress == LDNS_RR_COMPRESS)
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return sldns_rr_descript(t);
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return 0;
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}
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/** compress domain names in rdata, return RETVAL_* */
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static int
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compress_rdata(sldns_buffer* pkt, uint8_t* rdata, size_t todolen,
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struct regional* region, struct compress_tree_node** tree,
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const sldns_rr_descriptor* desc)
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{
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int labs, r, rdf = 0;
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size_t dname_len, len, pos = sldns_buffer_position(pkt);
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uint8_t count = desc->_dname_count;
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sldns_buffer_skip(pkt, 2); /* rdata len fill in later */
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/* space for rdatalen checked for already */
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rdata += 2;
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todolen -= 2;
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while(todolen > 0 && count) {
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switch(desc->_wireformat[rdf]) {
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case LDNS_RDF_TYPE_DNAME:
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labs = dname_count_size_labels(rdata, &dname_len);
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if((r=compress_any_dname(rdata, pkt, labs, region,
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tree)) != RETVAL_OK)
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return r;
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rdata += dname_len;
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todolen -= dname_len;
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count--;
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len = 0;
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break;
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case LDNS_RDF_TYPE_STR:
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len = *rdata + 1;
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break;
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default:
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len = get_rdf_size(desc->_wireformat[rdf]);
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}
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if(len) {
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/* copy over */
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if(sldns_buffer_remaining(pkt) < len)
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return RETVAL_TRUNC;
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sldns_buffer_write(pkt, rdata, len);
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todolen -= len;
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rdata += len;
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}
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rdf++;
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}
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/* copy remainder */
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if(todolen > 0) {
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if(sldns_buffer_remaining(pkt) < todolen)
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return RETVAL_TRUNC;
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sldns_buffer_write(pkt, rdata, todolen);
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}
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/* set rdata len */
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sldns_buffer_write_u16_at(pkt, pos, sldns_buffer_position(pkt)-pos-2);
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return RETVAL_OK;
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}
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/** Returns true if RR type should be included */
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static int
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rrset_belongs_in_reply(sldns_pkt_section s, uint16_t rrtype, uint16_t qtype,
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int dnssec)
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{
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if(dnssec)
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return 1;
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/* skip non DNSSEC types, except if directly queried for */
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if(s == LDNS_SECTION_ANSWER) {
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if(qtype == LDNS_RR_TYPE_ANY || qtype == rrtype)
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return 1;
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}
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/* check DNSSEC-ness */
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switch(rrtype) {
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case LDNS_RR_TYPE_SIG:
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case LDNS_RR_TYPE_KEY:
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case LDNS_RR_TYPE_NXT:
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case LDNS_RR_TYPE_DS:
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case LDNS_RR_TYPE_RRSIG:
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case LDNS_RR_TYPE_NSEC:
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case LDNS_RR_TYPE_DNSKEY:
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case LDNS_RR_TYPE_NSEC3:
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case LDNS_RR_TYPE_NSEC3PARAMS:
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return 0;
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}
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return 1;
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}
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/** store rrset in buffer in wireformat, return RETVAL_* */
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static int
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packed_rrset_encode(struct ub_packed_rrset_key* key, sldns_buffer* pkt,
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uint16_t* num_rrs, time_t timenow, struct regional* region,
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int do_data, int do_sig, struct compress_tree_node** tree,
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sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
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{
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size_t i, j, owner_pos;
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int r, owner_labs;
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uint16_t owner_ptr = 0;
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struct packed_rrset_data* data = (struct packed_rrset_data*)
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key->entry.data;
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/* does this RR type belong in the answer? */
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if(!rrset_belongs_in_reply(s, ntohs(key->rk.type), qtype, dnssec))
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return RETVAL_OK;
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owner_labs = dname_count_labels(key->rk.dname);
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owner_pos = sldns_buffer_position(pkt);
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if(do_data) {
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const sldns_rr_descriptor* c = type_rdata_compressable(key);
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for(i=0; i<data->count; i++) {
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/* rrset roundrobin */
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j = (i + rr_offset) % data->count;
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if((r=compress_owner(key, pkt, region, tree,
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owner_pos, &owner_ptr, owner_labs))
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!= RETVAL_OK)
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return r;
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sldns_buffer_write(pkt, &key->rk.type, 2);
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sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
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if(data->rr_ttl[j] < timenow)
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sldns_buffer_write_u32(pkt, 0);
|
|
else sldns_buffer_write_u32(pkt,
|
|
data->rr_ttl[j]-timenow);
|
|
if(c) {
|
|
if((r=compress_rdata(pkt, data->rr_data[j],
|
|
data->rr_len[j], region, tree, c))
|
|
!= RETVAL_OK)
|
|
return r;
|
|
} else {
|
|
if(sldns_buffer_remaining(pkt) < data->rr_len[j])
|
|
return RETVAL_TRUNC;
|
|
sldns_buffer_write(pkt, data->rr_data[j],
|
|
data->rr_len[j]);
|
|
}
|
|
}
|
|
}
|
|
/* insert rrsigs */
|
|
if(do_sig && dnssec) {
|
|
size_t total = data->count+data->rrsig_count;
|
|
for(i=data->count; i<total; i++) {
|
|
if(owner_ptr && owner_labs != 1) {
|
|
if(sldns_buffer_remaining(pkt) <
|
|
2+4+4+data->rr_len[i])
|
|
return RETVAL_TRUNC;
|
|
sldns_buffer_write(pkt, &owner_ptr, 2);
|
|
} else {
|
|
if((r=compress_any_dname(key->rk.dname,
|
|
pkt, owner_labs, region, tree))
|
|
!= RETVAL_OK)
|
|
return r;
|
|
if(sldns_buffer_remaining(pkt) <
|
|
4+4+data->rr_len[i])
|
|
return RETVAL_TRUNC;
|
|
}
|
|
sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_RRSIG);
|
|
sldns_buffer_write(pkt, &key->rk.rrset_class, 2);
|
|
if(data->rr_ttl[i] < timenow)
|
|
sldns_buffer_write_u32(pkt, 0);
|
|
else sldns_buffer_write_u32(pkt,
|
|
data->rr_ttl[i]-timenow);
|
|
/* rrsig rdata cannot be compressed, perform 100+ byte
|
|
* memcopy. */
|
|
sldns_buffer_write(pkt, data->rr_data[i],
|
|
data->rr_len[i]);
|
|
}
|
|
}
|
|
/* change rrnum only after we are sure it fits */
|
|
if(do_data)
|
|
*num_rrs += data->count;
|
|
if(do_sig && dnssec)
|
|
*num_rrs += data->rrsig_count;
|
|
|
|
return RETVAL_OK;
|
|
}
|
|
|
|
/** store msg section in wireformat buffer, return RETVAL_* */
|
|
static int
|
|
insert_section(struct reply_info* rep, size_t num_rrsets, uint16_t* num_rrs,
|
|
sldns_buffer* pkt, size_t rrsets_before, time_t timenow,
|
|
struct regional* region, struct compress_tree_node** tree,
|
|
sldns_pkt_section s, uint16_t qtype, int dnssec, size_t rr_offset)
|
|
{
|
|
int r;
|
|
size_t i, setstart;
|
|
*num_rrs = 0;
|
|
if(s != LDNS_SECTION_ADDITIONAL) {
|
|
if(s == LDNS_SECTION_ANSWER && qtype == LDNS_RR_TYPE_ANY)
|
|
dnssec = 1; /* include all types in ANY answer */
|
|
for(i=0; i<num_rrsets; i++) {
|
|
setstart = sldns_buffer_position(pkt);
|
|
if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
|
|
pkt, num_rrs, timenow, region, 1, 1, tree,
|
|
s, qtype, dnssec, rr_offset))
|
|
!= RETVAL_OK) {
|
|
/* Bad, but if due to size must set TC bit */
|
|
/* trim off the rrset neatly. */
|
|
sldns_buffer_set_position(pkt, setstart);
|
|
return r;
|
|
}
|
|
}
|
|
} else {
|
|
for(i=0; i<num_rrsets; i++) {
|
|
setstart = sldns_buffer_position(pkt);
|
|
if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
|
|
pkt, num_rrs, timenow, region, 1, 0, tree,
|
|
s, qtype, dnssec, rr_offset))
|
|
!= RETVAL_OK) {
|
|
sldns_buffer_set_position(pkt, setstart);
|
|
return r;
|
|
}
|
|
}
|
|
if(dnssec)
|
|
for(i=0; i<num_rrsets; i++) {
|
|
setstart = sldns_buffer_position(pkt);
|
|
if((r=packed_rrset_encode(rep->rrsets[rrsets_before+i],
|
|
pkt, num_rrs, timenow, region, 0, 1, tree,
|
|
s, qtype, dnssec, rr_offset))
|
|
!= RETVAL_OK) {
|
|
sldns_buffer_set_position(pkt, setstart);
|
|
return r;
|
|
}
|
|
}
|
|
}
|
|
return RETVAL_OK;
|
|
}
|
|
|
|
/** store query section in wireformat buffer, return RETVAL */
|
|
static int
|
|
insert_query(struct query_info* qinfo, struct compress_tree_node** tree,
|
|
sldns_buffer* buffer, struct regional* region)
|
|
{
|
|
if(sldns_buffer_remaining(buffer) <
|
|
qinfo->qname_len+sizeof(uint16_t)*2)
|
|
return RETVAL_TRUNC; /* buffer too small */
|
|
/* the query is the first name inserted into the tree */
|
|
if(!compress_tree_store(qinfo->qname,
|
|
dname_count_labels(qinfo->qname),
|
|
sldns_buffer_position(buffer), region, NULL, tree))
|
|
return RETVAL_OUTMEM;
|
|
if(sldns_buffer_current(buffer) == qinfo->qname)
|
|
sldns_buffer_skip(buffer, (ssize_t)qinfo->qname_len);
|
|
else sldns_buffer_write(buffer, qinfo->qname, qinfo->qname_len);
|
|
sldns_buffer_write_u16(buffer, qinfo->qtype);
|
|
sldns_buffer_write_u16(buffer, qinfo->qclass);
|
|
return RETVAL_OK;
|
|
}
|
|
|
|
static int
|
|
positive_answer(struct reply_info* rep, uint16_t qtype) {
|
|
size_t i;
|
|
if (FLAGS_GET_RCODE(rep->flags) != LDNS_RCODE_NOERROR)
|
|
return 0;
|
|
|
|
for(i=0;i<rep->an_numrrsets; i++) {
|
|
if(ntohs(rep->rrsets[i]->rk.type) == qtype) {
|
|
/* in case it is a wildcard with DNSSEC, there will
|
|
* be NSEC/NSEC3 records in the authority section
|
|
* that we cannot remove */
|
|
for(i=rep->an_numrrsets; i<rep->an_numrrsets+
|
|
rep->ns_numrrsets; i++) {
|
|
if(ntohs(rep->rrsets[i]->rk.type) ==
|
|
LDNS_RR_TYPE_NSEC ||
|
|
ntohs(rep->rrsets[i]->rk.type) ==
|
|
LDNS_RR_TYPE_NSEC3)
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int
|
|
reply_info_encode(struct query_info* qinfo, struct reply_info* rep,
|
|
uint16_t id, uint16_t flags, sldns_buffer* buffer, time_t timenow,
|
|
struct regional* region, uint16_t udpsize, int dnssec)
|
|
{
|
|
uint16_t ancount=0, nscount=0, arcount=0;
|
|
struct compress_tree_node* tree = 0;
|
|
int r;
|
|
size_t rr_offset;
|
|
|
|
sldns_buffer_clear(buffer);
|
|
if(udpsize < sldns_buffer_limit(buffer))
|
|
sldns_buffer_set_limit(buffer, udpsize);
|
|
if(sldns_buffer_remaining(buffer) < LDNS_HEADER_SIZE)
|
|
return 0;
|
|
|
|
sldns_buffer_write(buffer, &id, sizeof(uint16_t));
|
|
sldns_buffer_write_u16(buffer, flags);
|
|
sldns_buffer_write_u16(buffer, rep->qdcount);
|
|
/* set an, ns, ar counts to zero in case of small packets */
|
|
sldns_buffer_write(buffer, "\000\000\000\000\000\000", 6);
|
|
|
|
/* insert query section */
|
|
if(rep->qdcount) {
|
|
if((r=insert_query(qinfo, &tree, buffer, region)) !=
|
|
RETVAL_OK) {
|
|
if(r == RETVAL_TRUNC) {
|
|
/* create truncated message */
|
|
sldns_buffer_write_u16_at(buffer, 4, 0);
|
|
LDNS_TC_SET(sldns_buffer_begin(buffer));
|
|
sldns_buffer_flip(buffer);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
}
|
|
/* roundrobin offset. using query id for random number. With ntohs
|
|
* for different roundrobins for sequential id client senders. */
|
|
rr_offset = RRSET_ROUNDROBIN?ntohs(id):0;
|
|
|
|
/* insert answer section */
|
|
if((r=insert_section(rep, rep->an_numrrsets, &ancount, buffer,
|
|
0, timenow, region, &tree, LDNS_SECTION_ANSWER, qinfo->qtype,
|
|
dnssec, rr_offset)) != RETVAL_OK) {
|
|
if(r == RETVAL_TRUNC) {
|
|
/* create truncated message */
|
|
sldns_buffer_write_u16_at(buffer, 6, ancount);
|
|
LDNS_TC_SET(sldns_buffer_begin(buffer));
|
|
sldns_buffer_flip(buffer);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
sldns_buffer_write_u16_at(buffer, 6, ancount);
|
|
|
|
/* if response is positive answer, auth/add sections are not required */
|
|
if( ! (MINIMAL_RESPONSES && positive_answer(rep, qinfo->qtype)) ) {
|
|
/* insert auth section */
|
|
if((r=insert_section(rep, rep->ns_numrrsets, &nscount, buffer,
|
|
rep->an_numrrsets, timenow, region, &tree,
|
|
LDNS_SECTION_AUTHORITY, qinfo->qtype,
|
|
dnssec, rr_offset)) != RETVAL_OK) {
|
|
if(r == RETVAL_TRUNC) {
|
|
/* create truncated message */
|
|
sldns_buffer_write_u16_at(buffer, 8, nscount);
|
|
LDNS_TC_SET(sldns_buffer_begin(buffer));
|
|
sldns_buffer_flip(buffer);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
sldns_buffer_write_u16_at(buffer, 8, nscount);
|
|
|
|
/* insert add section */
|
|
if((r=insert_section(rep, rep->ar_numrrsets, &arcount, buffer,
|
|
rep->an_numrrsets + rep->ns_numrrsets, timenow, region,
|
|
&tree, LDNS_SECTION_ADDITIONAL, qinfo->qtype,
|
|
dnssec, rr_offset)) != RETVAL_OK) {
|
|
if(r == RETVAL_TRUNC) {
|
|
/* no need to set TC bit, this is the additional */
|
|
sldns_buffer_write_u16_at(buffer, 10, arcount);
|
|
sldns_buffer_flip(buffer);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
sldns_buffer_write_u16_at(buffer, 10, arcount);
|
|
}
|
|
sldns_buffer_flip(buffer);
|
|
return 1;
|
|
}
|
|
|
|
uint16_t
|
|
calc_edns_field_size(struct edns_data* edns)
|
|
{
|
|
if(!edns || !edns->edns_present)
|
|
return 0;
|
|
/* domain root '.' + type + class + ttl + rdatalen(=0) */
|
|
return 1 + 2 + 2 + 4 + 2;
|
|
}
|
|
|
|
void
|
|
attach_edns_record(sldns_buffer* pkt, struct edns_data* edns)
|
|
{
|
|
size_t len;
|
|
if(!edns || !edns->edns_present)
|
|
return;
|
|
/* inc additional count */
|
|
sldns_buffer_write_u16_at(pkt, 10,
|
|
sldns_buffer_read_u16_at(pkt, 10) + 1);
|
|
len = sldns_buffer_limit(pkt);
|
|
sldns_buffer_clear(pkt);
|
|
sldns_buffer_set_position(pkt, len);
|
|
/* write EDNS record */
|
|
sldns_buffer_write_u8(pkt, 0); /* '.' label */
|
|
sldns_buffer_write_u16(pkt, LDNS_RR_TYPE_OPT); /* type */
|
|
sldns_buffer_write_u16(pkt, edns->udp_size); /* class */
|
|
sldns_buffer_write_u8(pkt, edns->ext_rcode); /* ttl */
|
|
sldns_buffer_write_u8(pkt, edns->edns_version);
|
|
sldns_buffer_write_u16(pkt, edns->bits);
|
|
sldns_buffer_write_u16(pkt, 0); /* rdatalen */
|
|
sldns_buffer_flip(pkt);
|
|
}
|
|
|
|
int
|
|
reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
|
|
uint16_t id, uint16_t qflags, sldns_buffer* pkt, time_t timenow,
|
|
int cached, struct regional* region, uint16_t udpsize,
|
|
struct edns_data* edns, int dnssec, int secure)
|
|
{
|
|
uint16_t flags;
|
|
int attach_edns = 1;
|
|
|
|
if(!cached || rep->authoritative) {
|
|
/* original flags, copy RD and CD bits from query. */
|
|
flags = rep->flags | (qflags & (BIT_RD|BIT_CD));
|
|
} else {
|
|
/* remove AA bit, copy RD and CD bits from query. */
|
|
flags = (rep->flags & ~BIT_AA) | (qflags & (BIT_RD|BIT_CD));
|
|
}
|
|
if(secure && (dnssec || (qflags&BIT_AD)))
|
|
flags |= BIT_AD;
|
|
log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
|
|
if(udpsize < LDNS_HEADER_SIZE)
|
|
return 0;
|
|
if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) {
|
|
/* packet too small to contain edns, omit it. */
|
|
attach_edns = 0;
|
|
} else {
|
|
/* reserve space for edns record */
|
|
udpsize -= calc_edns_field_size(edns);
|
|
}
|
|
|
|
if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
|
|
udpsize, dnssec)) {
|
|
log_err("reply encode: out of memory");
|
|
return 0;
|
|
}
|
|
if(attach_edns)
|
|
attach_edns_record(pkt, edns);
|
|
return 1;
|
|
}
|
|
|
|
void
|
|
qinfo_query_encode(sldns_buffer* pkt, struct query_info* qinfo)
|
|
{
|
|
uint16_t flags = 0; /* QUERY, NOERROR */
|
|
sldns_buffer_clear(pkt);
|
|
log_assert(sldns_buffer_remaining(pkt) >= 12+255+4/*max query*/);
|
|
sldns_buffer_skip(pkt, 2); /* id done later */
|
|
sldns_buffer_write_u16(pkt, flags);
|
|
sldns_buffer_write_u16(pkt, 1); /* query count */
|
|
sldns_buffer_write(pkt, "\000\000\000\000\000\000", 6); /* counts */
|
|
sldns_buffer_write(pkt, qinfo->qname, qinfo->qname_len);
|
|
sldns_buffer_write_u16(pkt, qinfo->qtype);
|
|
sldns_buffer_write_u16(pkt, qinfo->qclass);
|
|
sldns_buffer_flip(pkt);
|
|
}
|
|
|
|
void
|
|
error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
|
|
uint16_t qid, uint16_t qflags, struct edns_data* edns)
|
|
{
|
|
uint16_t flags;
|
|
|
|
sldns_buffer_clear(buf);
|
|
sldns_buffer_write(buf, &qid, sizeof(uint16_t));
|
|
flags = (uint16_t)(BIT_QR | BIT_RA | r); /* QR and retcode*/
|
|
flags |= (qflags & (BIT_RD|BIT_CD)); /* copy RD and CD bit */
|
|
sldns_buffer_write_u16(buf, flags);
|
|
if(qinfo) flags = 1;
|
|
else flags = 0;
|
|
sldns_buffer_write_u16(buf, flags);
|
|
flags = 0;
|
|
sldns_buffer_write(buf, &flags, sizeof(uint16_t));
|
|
sldns_buffer_write(buf, &flags, sizeof(uint16_t));
|
|
sldns_buffer_write(buf, &flags, sizeof(uint16_t));
|
|
if(qinfo) {
|
|
if(sldns_buffer_current(buf) == qinfo->qname)
|
|
sldns_buffer_skip(buf, (ssize_t)qinfo->qname_len);
|
|
else sldns_buffer_write(buf, qinfo->qname, qinfo->qname_len);
|
|
sldns_buffer_write_u16(buf, qinfo->qtype);
|
|
sldns_buffer_write_u16(buf, qinfo->qclass);
|
|
}
|
|
sldns_buffer_flip(buf);
|
|
if(edns) {
|
|
struct edns_data es = *edns;
|
|
es.edns_version = EDNS_ADVERTISED_VERSION;
|
|
es.udp_size = EDNS_ADVERTISED_SIZE;
|
|
es.ext_rcode = 0;
|
|
es.bits &= EDNS_DO;
|
|
if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
|
|
edns->udp_size)
|
|
return;
|
|
attach_edns_record(buf, &es);
|
|
}
|
|
}
|