103 lines
3.8 KiB
C
103 lines
3.8 KiB
C
/* Copyright (c) 2003-2004, Roger Dingledine.
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* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
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* Copyright (c) 2007-2017, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file dns_structs.h
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*
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* \brief Structures used in dns.c. Exposed to dns.c, and to the unit tests
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* that declare DNS_PRIVATE.
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*/
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#ifndef TOR_DNS_STRUCTS_H
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#define TOR_DNS_STRUCTS_H
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/** Longest hostname we're willing to resolve. */
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#define MAX_ADDRESSLEN 256
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/** Linked list of connections waiting for a DNS answer. */
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typedef struct pending_connection_t {
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edge_connection_t *conn;
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struct pending_connection_t *next;
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} pending_connection_t;
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/** Value of 'magic' field for cached_resolve_t. Used to try to catch bad
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* pointers and memory stomping. */
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#define CACHED_RESOLVE_MAGIC 0x1234F00D
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/* Possible states for a cached resolve_t */
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/** We are waiting for the resolver system to tell us an answer here.
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* When we get one, or when we time out, the state of this cached_resolve_t
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* will become "DONE" and we'll possibly add a CACHED
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* entry. This cached_resolve_t will be in the hash table so that we will
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* know not to launch more requests for this addr, but rather to add more
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* connections to the pending list for the addr. */
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#define CACHE_STATE_PENDING 0
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/** This used to be a pending cached_resolve_t, and we got an answer for it.
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* Now we're waiting for this cached_resolve_t to expire. This should
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* have no pending connections, and should not appear in the hash table. */
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#define CACHE_STATE_DONE 1
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/** We are caching an answer for this address. This should have no pending
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* connections, and should appear in the hash table. */
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#define CACHE_STATE_CACHED 2
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/** @name status values for a single DNS request.
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*
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* @{ */
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/** The DNS request is in progress. */
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#define RES_STATUS_INFLIGHT 1
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/** The DNS request finished and gave an answer */
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#define RES_STATUS_DONE_OK 2
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/** The DNS request finished and gave an error */
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#define RES_STATUS_DONE_ERR 3
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/**@}*/
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/** A DNS request: possibly completed, possibly pending; cached_resolve
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* structs are stored at the OR side in a hash table, and as a linked
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* list from oldest to newest.
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*/
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typedef struct cached_resolve_t {
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HT_ENTRY(cached_resolve_t) node;
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uint32_t magic; /**< Must be CACHED_RESOLVE_MAGIC */
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char address[MAX_ADDRESSLEN]; /**< The hostname to be resolved. */
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union {
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uint32_t addr_ipv4; /**< IPv4 addr for <b>address</b>, if successful.
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* (In host order.) */
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int err_ipv4; /**< One of DNS_ERR_*, if IPv4 lookup failed. */
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} result_ipv4; /**< Outcome of IPv4 lookup */
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union {
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struct in6_addr addr_ipv6; /**< IPv6 addr for <b>address</b>, if
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* successful */
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int err_ipv6; /**< One of DNS_ERR_*, if IPv6 lookup failed. */
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} result_ipv6; /**< Outcome of IPv6 lookup, if any */
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union {
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char *hostname; /** A hostname, if PTR lookup happened successfully*/
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int err_hostname; /** One of DNS_ERR_*, if PTR lookup failed. */
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} result_ptr;
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/** @name Status fields
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*
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* These take one of the RES_STATUS_* values, depending on the state
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* of the corresponding lookup.
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*
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* @{ */
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unsigned int res_status_ipv4 : 2;
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unsigned int res_status_ipv6 : 2;
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unsigned int res_status_hostname : 2;
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/**@}*/
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uint8_t state; /**< Is this cached entry pending/done/informative? */
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time_t expire; /**< Remove items from cache after this time. */
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uint32_t ttl_ipv4; /**< What TTL did the nameserver tell us? */
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uint32_t ttl_ipv6; /**< What TTL did the nameserver tell us? */
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uint32_t ttl_hostname; /**< What TTL did the nameserver tell us? */
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/** Connections that want to know when we get an answer for this resolve. */
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pending_connection_t *pending_connections;
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/** Position of this element in the heap*/
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int minheap_idx;
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} cached_resolve_t;
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#endif /* !defined(TOR_DNS_STRUCTS_H) */
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