23f5d145ec
outstanding queries, and processing a DNS response packet was O(n) in the number of outstanding queries. To speed things up in Google, we added a few circular, doubly-linked lists of queries that are hash-bucketed based on the attributes we care about, so most important operations are now O(1). It might be that the number of buckets are higher than most people would need, but on a quick calculation it should only be 100kB or so even on a 64-bit system, so I've let it stay as-is.
353 lines
9.5 KiB
C
353 lines
9.5 KiB
C
#ifndef __ARES_PRIVATE_H
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#define __ARES_PRIVATE_H
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/* $Id$ */
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/* Copyright 1998 by the Massachusetts Institute of Technology.
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting
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* documentation, and that the name of M.I.T. not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* M.I.T. makes no representations about the suitability of
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* this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*/
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#include <stdio.h>
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#include <sys/types.h>
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#if !defined(WIN32) || defined(WATT32)
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#include <netinet/in.h>
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/* We define closesocket() here so that we can use this function all over
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the source code for closing sockets. */
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#define closesocket(x) close(x)
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#endif
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#ifdef WATT32
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#include <tcp.h>
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#include <sys/ioctl.h>
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#undef closesocket
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#define closesocket(s) close_s(s)
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#define writev(s,v,c) writev_s(s,v,c)
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#endif
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#ifdef NETWARE
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#include <time.h>
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#endif
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#define DEFAULT_TIMEOUT 5
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#define DEFAULT_TRIES 4
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#ifndef INADDR_NONE
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#define INADDR_NONE 0xffffffff
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#endif
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#if defined(WIN32) && !defined(WATT32)
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#define IS_NT() ((int)GetVersion() > 0)
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#define WIN_NS_9X "System\\CurrentControlSet\\Services\\VxD\\MSTCP"
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#define WIN_NS_NT_KEY "System\\CurrentControlSet\\Services\\Tcpip\\Parameters"
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#define NAMESERVER "NameServer"
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#define DHCPNAMESERVER "DhcpNameServer"
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#define DATABASEPATH "DatabasePath"
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#define WIN_PATH_HOSTS "\\hosts"
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#elif defined(WATT32)
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#define PATH_RESOLV_CONF "/dev/ENV/etc/resolv.conf"
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#elif defined(NETWARE)
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#define PATH_RESOLV_CONF "sys:/etc/resolv.cfg"
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#define PATH_HOSTS "sys:/etc/hosts"
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#elif defined(__riscos__)
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#define PATH_HOSTS "InetDBase:Hosts"
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#else
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#define PATH_RESOLV_CONF "/etc/resolv.conf"
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#ifdef ETC_INET
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#define PATH_HOSTS "/etc/inet/hosts"
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#else
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#define PATH_HOSTS "/etc/hosts"
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#endif
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#endif
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#define ARES_ID_KEY_LEN 31
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#include "ares_ipv6.h"
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struct query;
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/* Node definition for circular, doubly-linked list */
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struct list_node {
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struct list_node *prev;
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struct list_node *next;
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void* data;
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};
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struct send_request {
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/* Remaining data to send */
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const unsigned char *data;
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size_t len;
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/* The query for which we're sending this data */
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struct query* owner_query;
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/* The buffer we're using, if we have our own copy of the packet */
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unsigned char *data_storage;
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/* Next request in queue */
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struct send_request *next;
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};
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struct server_state {
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struct in_addr addr;
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ares_socket_t udp_socket;
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ares_socket_t tcp_socket;
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/* Mini-buffer for reading the length word */
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unsigned char tcp_lenbuf[2];
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int tcp_lenbuf_pos;
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int tcp_length;
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/* Buffer for reading actual TCP data */
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unsigned char *tcp_buffer;
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int tcp_buffer_pos;
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/* TCP output queue */
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struct send_request *qhead;
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struct send_request *qtail;
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/* Which incarnation of this connection is this? We don't want to
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* retransmit requests into the very same socket, but if the server
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* closes on us and we re-open the connection, then we do want to
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* re-send. */
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int tcp_connection_generation;
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/* Circular, doubly-linked list of outstanding queries to this server */
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struct list_node queries_to_server;
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/* Link back to owning channel */
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ares_channel channel;
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/* Is this server broken? We mark connections as broken when a
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* request that is queued for sending times out.
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*/
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int is_broken;
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};
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/* State to represent a DNS query */
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struct query {
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/* Query ID from qbuf, for faster lookup, and current timeout */
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unsigned short qid;
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time_t timeout;
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/*
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* Links for the doubly-linked lists in which we insert a query.
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* These circular, doubly-linked lists that are hash-bucketed based
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* the attributes we care about, help making most important
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* operations O(1).
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*/
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struct list_node queries_by_qid; /* hopefully in same cache line as qid */
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struct list_node queries_by_timeout;
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struct list_node queries_to_server;
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struct list_node all_queries;
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/* Query buf with length at beginning, for TCP transmission */
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unsigned char *tcpbuf;
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int tcplen;
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/* Arguments passed to ares_send() (qbuf points into tcpbuf) */
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const unsigned char *qbuf;
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int qlen;
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ares_callback callback;
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void *arg;
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/* Query status */
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int try;
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int server;
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struct query_server_info *server_info; /* per-server state */
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int using_tcp;
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int error_status;
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int timeouts; /* number of timeouts we saw for this request */
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};
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/* Per-server state for a query */
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struct query_server_info {
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int skip_server; /* should we skip server, due to errors, etc? */
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int tcp_connection_generation; /* into which TCP connection did we send? */
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};
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/* An IP address pattern; matches an IP address X if X & mask == addr */
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#define PATTERN_MASK 0x1
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#define PATTERN_CIDR 0x2
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union ares_addr {
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struct in_addr addr4;
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struct in6_addr addr6;
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};
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struct apattern {
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union ares_addr addr;
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union
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{
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union ares_addr addr;
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unsigned short bits;
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} mask;
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int family;
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unsigned short type;
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};
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typedef struct rc4_key
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{
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unsigned char state[256];
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unsigned char x;
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unsigned char y;
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} rc4_key;
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struct ares_channeldata {
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/* Configuration data */
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int flags;
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int timeout;
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int tries;
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int ndots;
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int udp_port;
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int tcp_port;
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int socket_send_buffer_size;
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int socket_receive_buffer_size;
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char **domains;
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int ndomains;
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struct apattern *sortlist;
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int nsort;
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char *lookups;
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/* Server addresses and communications state */
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struct server_state *servers;
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int nservers;
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/* ID to use for next query */
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unsigned short next_id;
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/* key to use when generating new ids */
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rc4_key id_key;
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/* Generation number to use for the next TCP socket open/close */
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int tcp_connection_generation;
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/* The time at which we last called process_timeouts() */
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time_t last_timeout_processed;
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/* Circular, doubly-linked list of queries, bucketed various ways.... */
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/* All active queries in a single list: */
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struct list_node all_queries;
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/* Queries bucketed by qid, for quickly dispatching DNS responses: */
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#define ARES_QID_TABLE_SIZE 2048
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struct list_node queries_by_qid[ARES_QID_TABLE_SIZE];
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/* Queries bucketed by timeout, for quickly handling timeouts: */
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#define ARES_TIMEOUT_TABLE_SIZE 1024
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struct list_node queries_by_timeout[ARES_TIMEOUT_TABLE_SIZE];
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ares_sock_state_cb sock_state_cb;
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void *sock_state_cb_data;
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};
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void ares__rc4(rc4_key* key,unsigned char *buffer_ptr, int buffer_len);
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void ares__send_query(ares_channel channel, struct query *query, time_t now);
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void ares__close_sockets(ares_channel channel, struct server_state *server);
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int ares__get_hostent(FILE *fp, int family, struct hostent **host);
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int ares__read_line(FILE *fp, char **buf, int *bufsize);
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void ares__free_query(struct query *query);
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short ares__generate_new_id(rc4_key* key);
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/* Routines for managing doubly-linked circular linked lists with a
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* dummy head.
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*/
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/* Initialize a new head node */
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static inline void ares__init_list_head(struct list_node* head) {
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head->prev = head;
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head->next = head;
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head->data = NULL;
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}
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/* Initialize a list node */
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static inline void ares__init_list_node(struct list_node* node, void* d) {
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node->prev = NULL;
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node->next = NULL;
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node->data = d;
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}
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/* Returns true iff the given list is empty */
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static inline int ares__is_list_empty(struct list_node* head) {
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return ((head->next == head) && (head->prev == head));
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}
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/* Inserts new_node before old_node */
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static inline void ares__insert_in_list(struct list_node* new_node,
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struct list_node* old_node) {
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new_node->next = old_node;
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new_node->prev = old_node->prev;
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old_node->prev->next = new_node;
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old_node->prev = new_node;
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}
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/* Removes the node from the list it's in, if any */
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static inline void ares__remove_from_list(struct list_node* node) {
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if (node->next != NULL) {
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node->prev->next = node->next;
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node->next->prev = node->prev;
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node->prev = NULL;
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node->next = NULL;
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}
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}
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/* Swap the contents of two lists */
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static inline void ares__swap_lists(struct list_node* head_a,
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struct list_node* head_b) {
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int is_a_empty = ares__is_list_empty(head_a);
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int is_b_empty = ares__is_list_empty(head_b);
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struct list_node old_a = *head_a;
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struct list_node old_b = *head_b;
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if (is_a_empty) {
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ares__init_list_head(head_b);
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} else {
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*head_b = old_a;
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old_a.next->prev = head_b;
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old_a.prev->next = head_b;
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}
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if (is_b_empty) {
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ares__init_list_head(head_a);
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} else {
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*head_a = old_b;
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old_b.next->prev = head_a;
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old_b.prev->next = head_a;
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}
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}
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#define ARES_SWAP_BYTE(a,b) \
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{ unsigned char swapByte = *(a); *(a) = *(b); *(b) = swapByte; }
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#define SOCK_STATE_CALLBACK(c, s, r, w) \
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do { \
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if ((c)->sock_state_cb) \
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(c)->sock_state_cb((c)->sock_state_cb_data, (s), (r), (w)); \
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} while (0)
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#ifdef CURLDEBUG
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/* This is low-level hard-hacking memory leak tracking and similar. Using the
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libcurl lowlevel code from within library is ugly and only works when
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c-ares is built and linked with a similarly debug-build libcurl, but we do
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this anyway for convenience. */
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#include "../lib/memdebug.h"
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#endif
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#endif /* __ARES_PRIVATE_H */
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