internal.h

adns for unix/linux, adns-1.3.tar.gz

/*
 * internal.h
 * - declarations of private objects with external linkage (adns__*)
 * - definitons of internal macros
 * - comments regarding library data structures
 */
/*
 *  This file is part of adns, which is
 *    Copyright (C) 1997-2000,2003,2006  Ian Jackson
 *    Copyright (C) 1999-2000,2003,2006  Tony Finch
 *    Copyright (C) 1991 Massachusetts Institute of Technology
 *  (See the file INSTALL for full details.)
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software Foundation,
 *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef ADNS_INTERNAL_H_INCLUDED
#define ADNS_INTERNAL_H_INCLUDED

#include "config.h"
typedef unsigned char byte;

#include <stdarg.h>
#include <assert.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>

#include <sys/time.h>

#include "adns.h"
#include "dlist.h"

#ifdef ADNS_REGRESS_TEST
# include "hredirect.h"
#endif

/* Configuration and constants */

#define MAXSERVERS 5
#define MAXSORTLIST 15
#define UDPMAXRETRIES 15
#define UDPRETRYMS 2000
#define TCPWAITMS 30000
#define TCPCONNMS 14000
#define TCPIDLEMS 30000
#define MAXTTLBELIEVE (7*86400) /* any TTL > 7 days is capped */

#define DNS_PORT 53
#define DNS_MAXUDP 512
#define DNS_MAXLABEL 63
#define DNS_MAXDOMAIN 255
#define DNS_HDRSIZE 12
#define DNS_IDOFFSET 0
#define DNS_CLASS_IN 1

#define DNS_INADDR_ARPA "in-addr", "arpa"

#define MAX_POLLFDS  ADNS_POLLFDS_RECOMMENDED

typedef enum {
  cc_user,
  cc_entex,
  cc_freq
} consistency_checks;

typedef enum {
  rcode_noerror,
  rcode_formaterror,
  rcode_servfail,
  rcode_nxdomain,
  rcode_notimp,
  rcode_refused
} dns_rcode;

/* Shared data structures */

typedef union {
  adns_status status;
  char *cp;
  adns_rrtype type;
  int i;
  struct in_addr ia;
  unsigned long ul;
} rr_align;

typedef struct {
  int used, avail;
  byte *buf;
} vbuf;

typedef struct {
  adns_state ads;
  adns_query qu;
  int serv;
  const byte *dgram;
  int dglen, nsstart, nscount, arcount;
  struct timeval now;
} parseinfo;

typedef struct typeinfo {
  adns_rrtype typekey;
  const char *rrtname;
  const char *fmtname;
  int rrsz;

  void (*makefinal)(adns_query qu, void *data);
  /* Change memory management of *data.
   * Previously, used alloc_interim, now use alloc_final.
   */

  adns_status (*convstring)(vbuf *vb, const void *data);
  /* Converts the RR data to a string representation in vbuf.
   * vbuf will be appended to (it must have been initialised),
   * and will not be null-terminated by convstring.
   */

  adns_status (*parse)(const parseinfo *pai, int cbyte,
		       int max, void *store_r);
  /* Parse one RR, in dgram of length dglen, starting at cbyte and
   * extending until at most max.
   *
   * The RR should be stored at *store_r, of length qu->typei->rrsz.
   *
   * If there is an overrun which might indicate truncation, it should set
   * *rdstart to -1; otherwise it may set it to anything else positive.
   *
   * nsstart is the offset of the authority section.
   */

  int (*diff_needswap)(adns_state ads,const void *datap_a,const void *datap_b);
  /* Returns !0 if RR a should be strictly after RR b in the sort order,
   * 0 otherwise.  Must not fail.
   */

  adns_status (*qdparselabel)(adns_state ads,
			      const char **p_io, const char *pe, int labelnum,
			      char label_r[DNS_MAXDOMAIN], int *ll_io,
			      adns_queryflags flags,
			      const struct typeinfo *typei);
  /* Parses one label from the query domain string.  On entry, *p_io
   * points to the next character to parse and *ll_io is the size of
   * the buffer.  pe points just after the end of the query domain
   * string.  On successful return, label_r[] and *ll_io are filled in
   * and *p_io points to *pe or just after the label-ending `.'.  */

  void (*postsort)(adns_state ads, void *array, int nrrs,
		   const struct typeinfo *typei);
  /* Called immediately after the RRs have been sorted, and may rearrange
   * them.  (This is really for the benefit of SRV's bizarre weighting
   * stuff.)  May be 0 to mean nothing needs to be done.
   */
} typeinfo;

adns_status adns__qdpl_normal(adns_state ads,
			      const char **p_io, const char *pe, int labelnum,
			      char label_r[], int *ll_io,
			      adns_queryflags flags,
			      const typeinfo *typei);
  /* implemented in transmit.c, used by types.c as default
   * and as part of implementation for some fancier types */

typedef struct allocnode {
  struct allocnode *next, *back;
} allocnode;

union maxalign {
  byte d[1];
  struct in_addr ia;
  long l;
  void *p;
  void (*fp)(void);
  union maxalign *up;
} data;

typedef struct {
  void *ext;
  void (*callback)(adns_query parent, adns_query child);
  union {
    adns_rr_addr ptr_parent_addr;
    adns_rr_hostaddr *hostaddr;
  } info;
} qcontext;

struct adns__query {
  adns_state ads;
  enum { query_tosend, query_tcpw, query_childw, query_done } state;
  adns_query back, next, parent;
  struct { adns_query head, tail; } children;
  struct { adns_query back, next; } siblings;
  struct { allocnode *head, *tail; } allocations;
  int interim_allocd, preserved_allocd;
  void *final_allocspace;

  const typeinfo *typei;
  byte *query_dgram;
  int query_dglen;

  vbuf vb;
  /* General-purpose messing-about buffer.
   * Wherever a `big' interface is crossed, this may be corrupted/changed
   * unless otherwise specified.
   */

  adns_answer *answer;
  /* This is allocated when a query is submitted, to avoid being unable
   * to relate errors to queries if we run out of memory.  During
   * query processing status, rrs is 0.  cname is set if
   * we found a cname (this corresponds to cname_dgram in the query
   * structure).  type is set from the word go.  nrrs and rrs
   * are set together, when we find how many rrs there are.
   * owner is set during querying unless we're doing searchlist,
   * in which case it is set only when we find an answer.
   */

  byte *cname_dgram;
  int cname_dglen, cname_begin;
  /* If non-0, has been allocated using . */

  vbuf search_vb;
  int search_origlen, search_pos, search_doneabs;
  /* Used by the searching algorithm.  The query domain in textual form
   * is copied into the vbuf, and _origlen set to its length.  Then
   * we walk the searchlist, if we want to.  _pos says where we are
   * (next entry to try), and _doneabs says whether we've done the
   * absolute query yet (0=not yet, 1=done, -1=must do straight away,
   * but not done yet).  If flags doesn't have adns_qf_search then
   * the vbuf is initialised but empty and everything else is zero.
   */

  int id, flags, retries;
  int udpnextserver;
  unsigned long udpsent; /* bitmap indexed by server */
  struct timeval timeout;
  time_t expires; /* Earliest expiry time of any record we used. */

  qcontext ctx;

  /* Possible states:
   *
   *  state   Queue   child  id   nextudpserver  udpsent     tcpfailed
   *
   *  tosend  NONE    null   >=0  0              zero        zero
   *  tosend  udpw    null   >=0  any            nonzero     zero
   *  tosend  NONE    null   >=0  any            nonzero     zero
   *
   *  tcpw    tcpw    null   >=0  irrelevant     any         any
   *
   *  child   childw  set    >=0  irrelevant     irrelevant  irrelevant
   *  child   NONE    null   >=0  irrelevant     irrelevant  irrelevant
   *  done    output  null   -1   irrelevant     irrelevant  irrelevant
   *
   * Queries are only not on a queue when they are actually being processed.
   * Queries in state tcpw/tcpw have been sent (or are in the to-send buffer)
   * iff the tcp connection is in state server_ok.
   *
   *			      +------------------------+
   *             START -----> |      tosend/NONE       |
   *			      +------------------------+
   *                         /                       |\  \
   *        too big for UDP /             UDP timeout  \  \ send via UDP
   *        send via TCP   /              more retries  \  \
   *        when conn'd   /                  desired     \  \
   *                     |     	       	       	       	  |  |
   *                     v				  |  v
   *              +-----------+         	    	+-------------+
   *              | tcpw/tcpw | ________                | tosend/udpw |
   *              +-----------+         \	    	+-------------+
   *                 |    |              |     UDP timeout | |
   *                 |    |              |      no more    | |
   *                 |    |              |      retries    | |
   *                  \   | TCP died     |      desired    | |
   *                   \   \ no more     |                 | |
   *                    \   \ servers    | TCP            /  |
   *                     \   \ to try    | timeout       /   |
   *                  got \   \          v             |_    | got
   *                 reply \   _| +------------------+      / reply
   *   	       	       	    \  	  | done/output FAIL |     /
   *                         \    +------------------+    /
   *                          \                          /
   *                           _|                      |_
   *                             (..... got reply ....)
   *                              /                   \
   *        need child query/ies /                     \ no child query
   *                            /                       \
   *                          |_                         _|
   *		   +---------------+		       +----------------+
   *               | childw/childw | ----------------> | done/output OK |
   *               +---------------+  children done    +----------------+
   */
};

struct query_queue { adns_query head, tail; };

struct adns__state {
  adns_initflags iflags;
  adns_logcallbackfn *logfn;
  void *logfndata;
  int configerrno;
  struct query_queue udpw, tcpw, childw, output;
  adns_query forallnext;
  int nextid, udpsocket, tcpsocket;
  vbuf tcpsend, tcprecv;
  int nservers, nsortlist, nsearchlist, searchndots, tcpserver, tcprecv_skip;
  enum adns__tcpstate {
    server_disconnected, server_connecting,
    server_ok, server_broken
  } tcpstate;
  struct timeval tcptimeout;
  /* This will have tv_sec==0 if it is not valid.  It will always be
   * valid if tcpstate _connecting.  When _ok, it will be nonzero if
   * we are idle (ie, tcpw queue is empty), in which case it is the
   * absolute time when we will close the connection.
   */
  struct sigaction stdsigpipe;
  sigset_t stdsigmask;
  struct pollfd pollfds_buf[MAX_POLLFDS];
  struct server {
    struct in_addr addr;
  } servers[MAXSERVERS];
  struct sortlist {
    struct in_addr base, mask;
  } sortlist[MAXSORTLIST];
  char **searchlist;
  unsigned short rand48xsubi[3];
};

/* From setup.c: */

int adns__setnonblock(adns_state ads, int fd); /* => errno value */

/* From general.c: */

void adns__vlprintf(adns_state ads, const char *fmt, va_list al);
void adns__lprintf(adns_state ads, const char *fmt,
		   ...) PRINTFFORMAT(2,3);

void adns__vdiag(adns_state ads, const char *pfx, adns_initflags prevent,
		 int serv, adns_query qu, const char *fmt, va_list al);

void adns__debug(adns_state ads, int serv, adns_query qu,
		 const char *fmt, ...) PRINTFFORMAT(4,5);
void adns__warn(adns_state ads, int serv, adns_query qu,
		const char *fmt, ...) PRINTFFORMAT(4,5);
void adns__diag(adns_state ads, int serv, adns_query qu,
		const char *fmt, ...) PRINTFFORMAT(4,5);

int adns__vbuf_ensure(vbuf *vb, int want);
int adns__vbuf_appendstr(vbuf *vb, const char *data); /* doesn't include nul */
int adns__vbuf_append(vbuf *vb, const byte *data, int len);
/* 1=>success, 0=>realloc failed */
void adns__vbuf_appendq(vbuf *vb, const byte *data, int len);
void adns__vbuf_init(vbuf *vb);
void adns__vbuf_free(vbuf *vb);

const char *adns__diag_domain(adns_state ads, int serv, adns_query qu,
			      vbuf *vb,
			      const byte *dgram, int dglen, int cbyte);
/* Unpicks a domain in a datagram and returns a string suitable for
 * printing it as.  Never fails - if an error occurs, it will
 * return some kind of string describing the error.
 *
 * serv may be -1 and qu may be 0.  vb must have been initialised,
 * and will be left in an arbitrary consistent state.
 *
 * Returns either vb->buf, or a pointer to a string literal.  Do not modify
 * vb before using the return value.