X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=adns.git;a=blobdiff_plain;f=src%2Fadns.h;h=dac2f57868ce4415c542c0c253b87cae63d4c7cd;hp=e70abd50c93e86a6583dba8e157fbc82b05be82a;hb=c912639e8f7077600caab8f25cad26d7779ba3d8;hpb=22181a31434b2439e41200ec65a95cb8605d41f5 diff --git a/src/adns.h b/src/adns.h index e70abd5..dac2f57 100644 --- a/src/adns.h +++ b/src/adns.h @@ -24,11 +24,17 @@ #ifndef ADNS_H_INCLUDED #define ADNS_H_INCLUDED +#ifdef __cplusplus +extern "C" { /* I really dislike this - iwj. */ +#endif #include #include #include +#include +#include +#include /* All struct in_addr anywhere in adns are in NETWORK byte order. */ @@ -43,18 +49,21 @@ typedef enum { adns_if_noautosys= 0x0010, /* do not make syscalls at every opportunity */ adns_if_eintr= 0x0020, /* allow _wait and _synchronous to return EINTR */ adns_if_nosigpipe= 0x0040, /* applic has SIGPIPE set to SIG_IGN, do not protect */ + adns_if_checkc_entex= 0x0100, /* do consistency checks on entry/exit to adns funcs */ + adns_if_checkc_freq= 0x0300, /* do consistency checks very frequently (slow!) */ } adns_initflags; typedef enum { - adns_qf_search= 0x000001, /* use the searchlist */ - adns_qf_usevc= 0x000002, /* use a virtual circuit (TCP connection) */ - adns_qf_owner= 0x000004, /* fill in the owner field in the answer */ - adns_qf_quoteok_query= 0x000010, /* allow quote-requiring chars in query domain */ - adns_qf_quoteok_cname= 0x000020, /* allow ... in CNAME we go via */ - adns_qf_quoteok_anshost= 0x000040, /* allow ... in answers expected to be hostnames */ - adns_qf_cname_loose= 0x000100, /* allow refs to CNAMEs - without, get _s_cname */ - adns_qf_cname_forbid= 0x000200, /* don't follow CNAMEs, instead give _s_cname */ - adns__qf_internalmask= 0x0ff000 + adns_qf_search= 0x00000001, /* use the searchlist */ + adns_qf_usevc= 0x00000002, /* use a virtual circuit (TCP connection) */ + adns_qf_owner= 0x00000004, /* fill in the owner field in the answer */ + adns_qf_quoteok_query= 0x00000010, /* allow quote-requiring chars in query domain */ + adns_qf_quoteok_cname= 0x00000000, /* allow ... in CNAME we go via - now default */ + adns_qf_quoteok_anshost= 0x00000040, /* allow ... in things supposed to be hostnames */ + adns_qf_quotefail_cname= 0x00000080, /* refuse if quote-req chars in CNAME we go via */ + adns_qf_cname_loose= 0x00000100, /* allow refs to CNAMEs - without, get _s_cname */ + adns_qf_cname_forbid= 0x00000200, /* don't follow CNAMEs, instead give _s_cname */ + adns__qf_internalmask= 0x0ff00000 } adns_queryflags; typedef enum { @@ -91,18 +100,57 @@ typedef enum { } adns_rrtype; -/* In queries without qtf_quoteok_*, all domains must have standard - * legal syntax. In queries _with_ qtf_anyquote, domains in the query - * or response may contain any characters, quoted according to - * RFC1035 5.1. On input to adns, the char* is a pointer to the - * interior of a " delimited string, except that " may appear in it, - * and on output, the char* is a pointer to a string which would be - * legal either inside or outside " delimiters, and any characters - * not usually legal in domain names will be quoted as \X - * (if the character is 33-126 except \ and ") or \DDD. - * - * Do not ask for _raw records containing mailboxes without - * specifying _qf_anyquote. +/* + * In queries without qf_quoteok_*, all domains must have standard + * legal syntax, or you get adns_s_querydomainvalid (if the query + * domain contains bad characters) or adns_s_answerdomaininvalid (if + * the answer contains bad characters). + * + * In queries _with_ qf_quoteok_*, domains in the query or response + * may contain any characters, quoted according to RFC1035 5.1. On + * input to adns, the char* is a pointer to the interior of a " + * delimited string, except that " may appear in it, and on output, + * the char* is a pointer to a string which would be legal either + * inside or outside " delimiters, and any characters not usually + * legal in domain names will be quoted as \X (if the character is + * 33-126 except \ and ") or \DDD. + * + * If the query goes via a CNAME then the canonical name (ie, the + * thing that the CNAME record refers to) is usually allowed to + * contain any characters, which will be quoted as above. With + * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when + * this happens. (This is a change from version 0.4 and earlier, in + * which failing the query was the default, and you had to say + * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.) + * + * In version 0.4 and earlier, asking for _raw records containing + * mailboxes without specifying _qf_quoteok_anshost was silly. This + * is no longer the case. In this version only parts of responses + * that are actually supposed to be hostnames will be refused by + * default if quote-requiring characters are found. + */ + +/* + * If you ask for an RR which contains domains which are actually + * encoded mailboxes, and don't ask for the _raw version, then adns + * returns the mailbox formatted suitably for an RFC822 recipient + * header field. The particular format used is that if the mailbox + * requires quoting according to the rules in RFC822 then the + * local-part is quoted in double quotes, which end at the next + * unescaped double quote. (\ is the escape char, and is doubled, and + * is used to escape only \ and ".) Otherwise the local-part is + * presented as-is. In any case this is followed by an @ and the + * domain. The domain will not contain any characters not legal in + * hostnames. adns will protect the application from local parts + * containing control characters - these appear to be legal according + * to RFC822 but are clearly a bad idea. + * + * If you ask for the domain with _raw then _no_ checking is done + * (even on the host part, regardless of adns_qf_quoteok_anshost), and + * you just get the domain name in master file format. + * + * If no mailbox is supplied the returned string will be `.' in either + * caswe. */ typedef enum { @@ -111,6 +159,9 @@ typedef enum { /* locally induced errors */ adns_s_nomemory, adns_s_unknownrrtype, + adns_s_systemfail, + + adns_s_max_localfail= 29, /* remotely induced errors, detected locally */ adns_s_timeout, @@ -118,6 +169,8 @@ typedef enum { adns_s_norecurse, adns_s_invalidresponse, adns_s_unknownformat, + + adns_s_max_remotefail= 59, /* remotely induced errors, reported by remote server to us */ adns_s_rcodeservfail, @@ -125,7 +178,7 @@ typedef enum { adns_s_rcodenotimplemented, adns_s_rcoderefused, adns_s_rcodeunknown, - + adns_s_max_tempfail= 99, /* remote configuration errors */ @@ -199,7 +252,7 @@ typedef struct { char *owner; /* only set if requested in query flags */ adns_rrtype type; /* guaranteed to be same as in query */ time_t expires; /* expiry time, defined only if _s_ok, nxdomain or nodata. NOT TTL! */ - int nrrs, rrsz; + int nrrs, rrsz; /* nrrs is 0 if an error occurs */ union { void *untyped; unsigned char *bytes; @@ -228,15 +281,25 @@ typedef struct { * If the call is successful, *query_io, *answer_r, and *context_r * will all be set. * Errors: - * Return values are 0 or an errno value; - * Seriously fatal system errors (eg, failure to create sockets, - * malloc failure, etc.) return errno values; - * Other errors (nameserver failure, timed out connections, &c) - * are returned in the status field of the answer. If status is - * nonzero then nrrs will be 0, otherwise it will be >0. - * type will always be the type requested; - * If no (appropriate) requests are done adns_check returns EWOULDBLOCK; - * If no (appropriate) requests are outstanding adns_query and adns_wait return ESRCH; + * Return values are 0 or an errno value. + * + * For _init, _init_strcfg, _submit and _synchronous, system errors + * (eg, failure to create sockets, malloc failure, etc.) return errno + * values. + * + * For _wait and _check failures are reported in the answer + * structure, and only 0, ESRCH or (for _check) EWOULDBLOCK is + * returned: if no (appropriate) requests are done adns_check returns + * EWOULDBLOCK; if no (appropriate) requests are outstanding both + * adns_query and adns_wait return ESRCH. + * + * Additionally, _wait can return EINTR if you set adns_if_eintr. + * + * All other errors (nameserver failure, timed out connections, &c) + * are returned in the status field of the answer. After a + * successful _wait or _check, if status is nonzero then nrrs will be + * 0, otherwise it will be >0. type will always be the type + * requested. */ int adns_init(adns_state *newstate_r, adns_initflags flags, @@ -252,8 +315,8 @@ int adns_synchronous(adns_state ads, adns_answer **answer_r); /* NB: if you set adns_if_noautosys then _submit and _check do not - * make any system calls; you must use adns_callback (possibly after - * adns_interest) to actually get things to happen. + * make any system calls; you must use some of the asynch-io event + * processing functions to actually get things to happen. */ int adns_submit(adns_state ads, @@ -272,40 +335,61 @@ int adns_wait(adns_state ads, adns_query *query_io, adns_answer **answer_r, void **context_r); -/* fixme: minor cache */ void adns_cancel(adns_query query); -void adns_finish(adns_state); +/* The adns_query you get back from _submit is valid (ie, can be + * legitimately passed into adns functions) until it is returned by + * adns_check or adns_wait, or passed to adns_cancel. After that it + * must not be used. You can rely on it not being reused until the + * first adns_submit or _transact call using the same adns_state after + * it became invalid, so you may compare it for equality with other + * query handles until you next call _query or _transact. + * + * _submit and _synchronous return ENOSYS if they don't understand the + * query type. + */ + +int adns_submit_reverse(adns_state ads, + const struct sockaddr *addr, + adns_rrtype type, + adns_queryflags flags, + void *context, + adns_query *query_r); +/* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored. */ + +void adns_finish(adns_state ads); /* You may call this even if you have queries outstanding; * they will be cancelled. */ -int adns_callback(adns_state, int maxfd, const fd_set *readfds, const fd_set *writefds, - const fd_set *exceptfds); -/* Gives adns flow-of-control for a bit. This will never block. - * If maxfd == -1 then adns will check (make nonblocking system calls on) - * all of its own filedescriptors; otherwise it will only use those - * < maxfd and specified in the fd_set's, as if select had returned them. - * Other fd's may be in the fd_sets, and will be ignored. - * _callback returns how many adns fd's were in the various sets, so - * you can tell if your select handling code has missed something and is going awol. - * - * May also return -1 if a critical syscall failed, setting errno. + +void adns_forallqueries_begin(adns_state ads); +adns_query adns_forallqueries_next(adns_state ads, void **context_r); +/* Iterator functions, which you can use to loop over the outstanding + * (submitted but not yet successfuly checked/waited) queries. + * + * You can only have one iteration going at once. You may call _begin + * at any time; after that, an iteration will be in progress. You may + * only call _next when an iteration is in progress - anything else + * may coredump. The iteration remains in progress until _next + * returns 0, indicating that all the queries have been walked over, + * or ANY other adns function is called with the same adns_state (or a + * query in the same adns_state). There is no need to explicitly + * finish an iteration. + * + * context_r may be 0. *context_r may not be set when _next returns 0. */ -void adns_interest(adns_state, int *maxfd_io, fd_set *readfds_io, - fd_set *writefds_io, fd_set *exceptfds_io, - struct timeval **tv_mod, struct timeval *tv_buf); -/* Find out file descriptors adns is interested in, and when it - * would like the opportunity to time something out. If you do not plan to - * block then tv_mod may be 0. Otherwise, tv_mod may point to 0 meaning - * you have no timeout of your own, in which case tv_buf must be non-null and - * _interest may fill it in and set *tv_mod=tv_buf. - * readfds, writefds, exceptfds and maxfd may not be 0. +void adns_checkconsistency(adns_state ads, adns_query qu); +/* Checks the consistency of adns's internal data structures. + * If any error is found, the program will abort(). + * You may pass 0 for qu; if you pass non-null then additional checks + * are done to make sure that qu is a valid query. */ -/* Example expected/legal calling sequences: +/* + * Example expected/legal calling sequence for submit/check/wait: * adns_init * adns_submit 1 * adns_submit 2 @@ -316,37 +400,223 @@ void adns_interest(adns_state, int *maxfd_io, fd_set *readfds_io, * adns_wait 3 * .... * adns_finish + */ + +/* + * Entrypoints for generic asynch io: + * (these entrypoints are not very useful except in combination with * + * some of the other I/O model calls which can tell you which fds to + * be interested in): + * + * Note that any adns call may cause adns to open and close fds, so + * you must call beforeselect or beforepoll again just before + * blocking, or you may not have an up-to-date list of it's fds. + */ + +int adns_processany(adns_state ads); +/* Gives adns flow-of-control for a bit. This will never block, and + * can be used with any threading/asynch-io model. If some error + * occurred which might cause an event loop to spin then the errno + * value is returned. + */ + +int adns_processreadable(adns_state ads, int fd, const struct timeval *now); +int adns_processwriteable(adns_state ads, int fd, const struct timeval *now); +int adns_processexceptional(adns_state ads, int fd, const struct timeval *now); +/* Gives adns flow-of-control so that it can process incoming data + * from, or send outgoing data via, fd. Very like _processany. If it + * returns zero then fd will no longer be readable or writeable + * (unless of course more data has arrived since). adns will _only_ + * that fd and only in the manner specified, regardless of whether + * adns_if_noautosys was specified. + * + * adns_processexceptional should be called when select(2) reports an + * exceptional condition, or poll(2) reports POLLPRI. + * + * It is fine to call _processreabable or _processwriteable when the + * fd is not ready, or with an fd that doesn't belong to adns; it will + * then just return 0. + * + * If some error occurred which might prevent an event loop to spin + * then the errno value is returned. + */ + +void adns_processtimeouts(adns_state ads, const struct timeval *now); +/* Gives adns flow-of-control so that it can process any timeouts + * which might have happened. Very like _processreadable/writeable. + * + * now may be 0; if it isn't, *now must be the current time, recently + * obtained from gettimeofday. + */ + +void adns_firsttimeout(adns_state ads, + struct timeval **tv_mod, struct timeval *tv_buf, + struct timeval now); +/* Asks adns when it would first like the opportunity to time + * something out. now must be the current time, from gettimeofday. + * + * If tv_mod points to 0 then tv_buf must be non-null, and + * _firsttimeout will fill in *tv_buf with the time until the first + * timeout, and make *tv_mod point to tv_buf. If adns doesn't have + * anything that might need timing out it will leave *tv_mod as 0. + * + * If *tv_mod is not 0 then tv_buf is not used. adns will update + * *tv_mod if it has any earlier timeout, and leave it alone if it + * doesn't. + * + * This call will not actually do any I/O, or change the fds that adns + * is using. It always succeeds and never blocks. + */ + +void adns_globalsystemfailure(adns_state ads); +/* If serious problem(s) happen which globally affect your ability to + * interact properly with adns, or adns's ability to function + * properly, you or adns can call this function. + * + * All currently outstanding queries will be made to fail with + * adns_s_systemfail, and adns will close any stream sockets it has + * open. + * + * This is used by adns, for example, if gettimeofday() fails. + * Without this the program's event loop might start to spin ! + * + * This call will never block. + */ + +/* + * Entrypoints for select-loop based asynch io: + */ + +void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds, + fd_set *writefds, fd_set *exceptfds, + struct timeval **tv_mod, struct timeval *tv_buf, + const struct timeval *now); +/* Find out file descriptors adns is interested in, and when it would + * like the opportunity to time something out. If you do not plan to + * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as + * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may + * not be 0. + * + * If *now is not 0 then this will never actually do any I/O, or + * change the fds that adns is using or the timeouts it wants. In any + * case it won't block. + */ + +void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds, + const fd_set *writefds, const fd_set *exceptfds, + const struct timeval *now); +/* Gives adns flow-of-control for a bit; intended for use after + * select. This is just a fancy way of calling adns_processreadable/ + * writeable/timeouts as appropriate, as if select had returned the + * data being passed. Always succeeds. + */ + +/* + * Example calling sequence: * * adns_init _noautosys * loop { - * adns_interest + * adns_beforeselect * select - * adns_callback + * adns_afterselect * ... * adns_submit / adns_check * ... * } */ +/* + * Entrypoints for poll-loop based asynch io: + */ + +struct pollfd; +/* In case your system doesn't have it or you forgot to include + * , to stop the following declarations from causing + * problems. If your system doesn't have poll then the following + * entrypoints will not be defined in libadns. Sorry ! + */ + +int adns_beforepoll(adns_state ads, struct pollfd *fds, int *nfds_io, int *timeout_io, + const struct timeval *now); +/* Finds out which fd's adns is interested in, and when it would like + * to be able to time things out. This is in a form suitable for use + * with poll(2). + * + * On entry, usually fds should point to at least *nfds_io structs. + * adns will fill up to that many structs will information for poll, + * and record in *nfds_io how many structs it filled. If it wants to + * listen for more structs then *nfds_io will be set to the number + * required and _beforepoll will return ERANGE. + * + * You may call _beforepoll with fds==0 and *nfds_io 0, in which case + * adns will fill in the number of fds that it might be interested in + * in *nfds_io, and always return either 0 (if it is not interested in + * any fds) or ERANGE (if it is). + * + * NOTE that (unless now is 0) adns may acquire additional fds + * from one call to the next, so you must put adns_beforepoll in a + * loop, rather than assuming that the second call (with the buffer + * size requested by the first) will not return ERANGE. + * + * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd + * structs, and only ever looks at those bits. POLLPRI is required to + * detect TCP Urgent Data (which should not be used by a DNS server) + * so that adns can know that the TCP stream is now useless. + * + * In any case, *timeout_io should be a timeout value as for poll(2), + * which adns will modify downwards as required. If the caller does + * not plan to block then *timeout_io should be 0 on entry, or + * alternatively, timeout_io may be 0. (Alternatively, the caller may + * use _beforeselect with timeout_io==0 to find out about file + * descriptors, and use _firsttimeout is used to find out when adns + * might want to time something out.) + * + * adns_beforepoll will return 0 on success, and will not fail for any + * reason other than the fds buffer being too small (ERANGE). + * + * This call will never actually do any I/O. If you supply the + * current time it will not change the fds that adns is using or the + * timeouts it wants. + * + * In any case this call won't block. + */ + +#define ADNS_POLLFDS_RECOMMENDED 2 +/* If you allocate an fds buf with at least RECOMMENDED entries then + * you are unlikely to need to enlarge it. You are recommended to do + * so if it's convenient. However, you must be prepared for adns to + * require more space than this. + */ + +void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds, + const struct timeval *now); +/* Gives adns flow-of-control for a bit; intended for use after + * poll(2). fds and nfds should be the results from poll(). pollfd + * structs mentioning fds not belonging to adns will be ignored. + */ + + adns_status adns_rr_info(adns_rrtype type, const char **rrtname_r, const char **fmtname_r, int *len_r, const void *datap, char **data_r); -/* Gets information in human-readable (but non-i18n) form - * for eg debugging purposes. type must be specified, - * and the official name of the corresponding RR type will - * be returned in *rrtname_r, and information about the processing - * style in *fmtname_r. The length of the table entry in an answer - * for that type will be returned in in *len_r. - * Any or all of rrtname_r, fmtname_r and len_r may be 0. - * If fmtname_r is non-null then *fmtname_r may be - * null on return, indicating that no special processing is - * involved. - * - * data_r be must be non-null iff datap is. In this case - * *data_r will be set to point to a human-readable text - * string representing the RR data. The text will have - * been obtained from malloc() and must be freed by the caller. +/* + + * Get information about a query type, or convert reply data to a + * textual form. type must be specified, and the official name of the + * corresponding RR type will be returned in *rrtname_r, and + * information about the processing style in *fmtname_r. The length + * of the table entry in an answer for that type will be returned in + * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0. + * If fmtname_r is non-null then *fmtname_r may be null on return, + * indicating that no special processing is involved. + * + * data_r be must be non-null iff datap is. In this case *data_r will + * be set to point to a string pointing to a representation of the RR + * data in master file format. (The owner name, timeout, class and + * type will not be present - only the data part of the RR.) The + * memory will have been obtained from malloc() and must be freed by + * the caller. * * Usually this routine will succeed. Possible errors include: * adns_s_nomemory @@ -354,8 +624,48 @@ adns_status adns_rr_info(adns_rrtype type, * adns_s_invaliddata (*datap contained garbage) * If an error occurs then no memory has been allocated, * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined. + * + * There are some adns-invented data formats which are not official + * master file formats. These include: + * + * Mailboxes if __qtf_mail822: these are just included as-is. + * + * Addresses (adns_rr_addr): these may be of pretty much any type. + * The representation is in two parts: first, a word for the address + * family (ie, in AF_XXX, the XXX), and then one or more items for the + * address itself, depending on the format. For an IPv4 address the + * syntax is INET followed by the dotted quad (from inet_ntoa). + * Currently only IPv4 is supported. + * + * Text strings (as in adns_rr_txt) appear inside double quotes, and + * use \" and \\ to represent " and \, and \xHH to represent + * characters not in the range 32-126. + * + * Hostname with addresses (adns_rr_hostaddr): this consists of the + * hostname, as usual, followed by the adns_status value, as an + * abbreviation, and then a descriptive string (encoded as if it were + * a piece of text), for the address lookup, followed by zero or more + * addresses enclosed in ( and ). If the result was a permanent + * failure, then a single ? appears instead of the ( ). If the + * result was a temporary failure then an empty pair of parentheses + * appears (which a space in between). For example, one of the NS + * records for greenend.org.uk comes out like + * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 ) + * an MX referring to a nonexistent host might come out like: + * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( ) + * and if nameserver information is not available you might get: + * dns2.spong.dyn.ml.org timeout "DNS query timed out" ? */ const char *adns_strerror(adns_status st); +const char *adns_errabbrev(adns_status st); +/* Like strerror but for adns_status values. adns_errabbrev returns + * the abbreviation of the error - eg, for adns_s_timeout it returns + * "timeout". You MUST NOT call these functions with status values + * not returned by the same adns library. + */ +#ifdef __cplusplus +} /* end of extern "C" */ +#endif #endif