X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/051018257599e8a91f4ba2c2c99b72697eb0a4a4..d4095f83496094d7d8649cc412536f69d1cfcb6a:/src/src/verify.c diff --git a/src/src/verify.c b/src/src/verify.c index a0ab1b873..efc05fcf1 100644 --- a/src/src/verify.c +++ b/src/src/verify.c @@ -19,27 +19,6 @@ static smtp_context ctctx; uschar ctbuffer[8192]; -/* Structure for caching DNSBL lookups */ - -typedef struct dnsbl_cache_block { - time_t expiry; - dns_address *rhs; - uschar *text; - int rc; - BOOL text_set; -} dnsbl_cache_block; - - -/* Anchor for DNSBL cache */ - -static tree_node *dnsbl_cache = NULL; - - -/* Bits for match_type in one_check_dnsbl() */ - -#define MT_NOT 1 -#define MT_ALL 2 - static uschar cutthrough_response(client_conn_ctx *, char, uschar **, int); @@ -3365,575 +3344,6 @@ same format string, "%s.%s" */ -/************************************************* -* Perform a single dnsbl lookup * -*************************************************/ - -/* This function is called from verify_check_dnsbl() below. It is also called -recursively from within itself when domain and domain_txt are different -pointers, in order to get the TXT record from the alternate domain. - -Arguments: - domain the outer dnsbl domain - domain_txt alternate domain to lookup TXT record on success; when the - same domain is to be used, domain_txt == domain (that is, - the pointers must be identical, not just the text) - keydomain the current keydomain (for debug message) - prepend subdomain to lookup (like keydomain, but - reversed if IP address) - iplist the list of matching IP addresses, or NULL for "any" - bitmask true if bitmask matching is wanted - match_type condition for 'succeed' result - 0 => Any RR in iplist (=) - 1 => No RR in iplist (!=) - 2 => All RRs in iplist (==) - 3 => Some RRs not in iplist (!==) - the two bits are defined as MT_NOT and MT_ALL - defer_return what to return for a defer - -Returns: OK if lookup succeeded - FAIL if not -*/ - -static int -one_check_dnsbl(uschar *domain, uschar *domain_txt, uschar *keydomain, - uschar *prepend, uschar *iplist, BOOL bitmask, int match_type, - int defer_return) -{ -dns_answer * dnsa = store_get_dns_answer(); -dns_scan dnss; -tree_node *t; -dnsbl_cache_block *cb; -int old_pool = store_pool; -uschar * query; -int qlen; - -/* Construct the specific query domainname */ - -query = string_sprintf("%s.%s", prepend, domain); -if ((qlen = Ustrlen(query)) >= 256) - { - log_write(0, LOG_MAIN|LOG_PANIC, "dnslist query is too long " - "(ignored): %s...", query); - return FAIL; - } - -/* Look for this query in the cache. */ - -if ( (t = tree_search(dnsbl_cache, query)) - && (cb = t->data.ptr)->expiry > time(NULL) - ) - -/* Previous lookup was cached */ - - { - HDEBUG(D_dnsbl) debug_printf("dnslists: using result of previous lookup\n"); - } - -/* If not cached from a previous lookup, we must do a DNS lookup, and -cache the result in permanent memory. */ - -else - { - uint ttl = 3600; /* max TTL for positive cache entries */ - - store_pool = POOL_PERM; - - if (t) - { - HDEBUG(D_dnsbl) debug_printf("cached data found but past valid time; "); - } - - else - { /* Set up a tree entry to cache the lookup */ - t = store_get(sizeof(tree_node) + qlen + 1 + 1, is_tainted(query)); - Ustrcpy(t->name, query); - t->data.ptr = cb = store_get(sizeof(dnsbl_cache_block), FALSE); - (void)tree_insertnode(&dnsbl_cache, t); - } - - /* Do the DNS lookup . */ - - HDEBUG(D_dnsbl) debug_printf("new DNS lookup for %s\n", query); - cb->rc = dns_basic_lookup(dnsa, query, T_A); - cb->text_set = FALSE; - cb->text = NULL; - cb->rhs = NULL; - - /* If the lookup succeeded, cache the RHS address. The code allows for - more than one address - this was for complete generality and the possible - use of A6 records. However, A6 records are no longer supported. Leave the code - here, just in case. - - Quite apart from one A6 RR generating multiple addresses, there are DNS - lists that return more than one A record, so we must handle multiple - addresses generated in that way as well. - - Mark the cache entry with the "now" plus the minimum of the address TTLs, - or the RFC 2308 negative-cache value from the SOA if none were found. */ - - switch (cb->rc) - { - case DNS_SUCCEED: - { - dns_address ** addrp = &cb->rhs; - dns_address * da; - for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; - rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) - if (rr->type == T_A && (da = dns_address_from_rr(dnsa, rr))) - { - *addrp = da; - while (da->next) da = da->next; - addrp = &da->next; - if (ttl > rr->ttl) ttl = rr->ttl; - } - - if (cb->rhs) - { - cb->expiry = time(NULL) + ttl; - break; - } - - /* If we didn't find any A records, change the return code. This can - happen when there is a CNAME record but there are no A records for what - it points to. */ - - cb->rc = DNS_NODATA; - } - /*FALLTHROUGH*/ - - case DNS_NOMATCH: - case DNS_NODATA: - { - /* Although there already is a neg-cache layer maintained by - dns_basic_lookup(), we have a dnslist cache entry allocated and - tree-inserted. So we may as well use it. */ - - time_t soa_negttl = dns_expire_from_soa(dnsa, T_A); - cb->expiry = soa_negttl ? soa_negttl : time(NULL) + ttl; - break; - } - - default: - cb->expiry = time(NULL) + ttl; - break; - } - - store_pool = old_pool; - HDEBUG(D_dnsbl) debug_printf("dnslists: wrote cache entry, ttl=%d\n", - (int)(cb->expiry - time(NULL))); - } - -/* We now have the result of the DNS lookup, either newly done, or cached -from a previous call. If the lookup succeeded, check against the address -list if there is one. This may be a positive equality list (introduced by -"="), a negative equality list (introduced by "!="), a positive bitmask -list (introduced by "&"), or a negative bitmask list (introduced by "!&").*/ - -if (cb->rc == DNS_SUCCEED) - { - dns_address * da = NULL; - uschar *addlist = cb->rhs->address; - - /* For A and AAAA records, there may be multiple addresses from multiple - records. For A6 records (currently not expected to be used) there may be - multiple addresses from a single record. */ - - for (da = cb->rhs->next; da; da = da->next) - addlist = string_sprintf("%s, %s", addlist, da->address); - - HDEBUG(D_dnsbl) debug_printf("DNS lookup for %s succeeded (yielding %s)\n", - query, addlist); - - /* Address list check; this can be either for equality, or via a bitmask. - In the latter case, all the bits must match. */ - - if (iplist) - { - for (da = cb->rhs; da; da = da->next) - { - int ipsep = ','; - const uschar *ptr = iplist; - uschar *res; - - /* Handle exact matching */ - - if (!bitmask) - { - while ((res = string_nextinlist(&ptr, &ipsep, NULL, 0))) - if (Ustrcmp(CS da->address, res) == 0) - break; - } - - /* Handle bitmask matching */ - - else - { - int address[4]; - int mask = 0; - - /* At present, all known DNS blocking lists use A records, with - IPv4 addresses on the RHS encoding the information they return. I - wonder if this will linger on as the last vestige of IPv4 when IPv6 - is ubiquitous? Anyway, for now we use paranoia code to completely - ignore IPv6 addresses. The default mask is 0, which always matches. - We change this only for IPv4 addresses in the list. */ - - if (host_aton(da->address, address) == 1) mask = address[0]; - - /* Scan the returned addresses, skipping any that are IPv6 */ - - while ((res = string_nextinlist(&ptr, &ipsep, NULL, 0))) - { - if (host_aton(res, address) != 1) continue; - if ((address[0] & mask) == address[0]) break; - } - } - - /* If either - - (a) An IP address in an any ('=') list matched, or - (b) No IP address in an all ('==') list matched - - then we're done searching. */ - - if (((match_type & MT_ALL) != 0) == (res == NULL)) break; - } - - /* If da == NULL, either - - (a) No IP address in an any ('=') list matched, or - (b) An IP address in an all ('==') list didn't match - - so behave as if the DNSBL lookup had not succeeded, i.e. the host is not on - the list. */ - - if ((match_type == MT_NOT || match_type == MT_ALL) != (da == NULL)) - { - HDEBUG(D_dnsbl) - { - uschar *res = NULL; - switch(match_type) - { - case 0: - res = US"was no match"; break; - case MT_NOT: - res = US"was an exclude match"; break; - case MT_ALL: - res = US"was an IP address that did not match"; break; - case MT_NOT|MT_ALL: - res = US"were no IP addresses that did not match"; break; - } - debug_printf("=> but we are not accepting this block class because\n"); - debug_printf("=> there %s for %s%c%s\n", - res, - ((match_type & MT_ALL) == 0)? "" : "=", - bitmask? '&' : '=', iplist); - } - return FAIL; - } - } - - /* Either there was no IP list, or the record matched, implying that the - domain is on the list. We now want to find a corresponding TXT record. If an - alternate domain is specified for the TXT record, call this function - recursively to look that up; this has the side effect of re-checking that - there is indeed an A record at the alternate domain. */ - - if (domain_txt != domain) - return one_check_dnsbl(domain_txt, domain_txt, keydomain, prepend, NULL, - FALSE, match_type, defer_return); - - /* If there is no alternate domain, look up a TXT record in the main domain - if it has not previously been cached. */ - - if (!cb->text_set) - { - cb->text_set = TRUE; - if (dns_basic_lookup(dnsa, query, T_TXT) == DNS_SUCCEED) - for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr; - rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) - if (rr->type == T_TXT) - { - int len = (rr->data)[0]; - if (len > 511) len = 127; - store_pool = POOL_PERM; - cb->text = string_sprintf("%.*s", len, CUS (rr->data+1)); - store_pool = old_pool; - break; - } - } - - dnslist_value = addlist; - dnslist_text = cb->text; - return OK; - } - -/* There was a problem with the DNS lookup */ - -if (cb->rc != DNS_NOMATCH && cb->rc != DNS_NODATA) - { - log_write(L_dnslist_defer, LOG_MAIN, - "DNS list lookup defer (probably timeout) for %s: %s", query, - (defer_return == OK)? US"assumed in list" : - (defer_return == FAIL)? US"assumed not in list" : - US"returned DEFER"); - return defer_return; - } - -/* No entry was found in the DNS; continue for next domain */ - -HDEBUG(D_dnsbl) - { - debug_printf("DNS lookup for %s failed\n", query); - debug_printf("=> that means %s is not listed at %s\n", - keydomain, domain); - } - -return FAIL; -} - - - - -/************************************************* -* Check host against DNS black lists * -*************************************************/ - -/* This function runs checks against a list of DNS black lists, until one -matches. Each item on the list can be of the form - - domain=ip-address/key - -The domain is the right-most domain that is used for the query, for example, -blackholes.mail-abuse.org. If the IP address is present, there is a match only -if the DNS lookup returns a matching IP address. Several addresses may be -given, comma-separated, for example: x.y.z=127.0.0.1,127.0.0.2. - -If no key is given, what is looked up in the domain is the inverted IP address -of the current client host. If a key is given, it is used to construct the -domain for the lookup. For example: - - dsn.rfc-ignorant.org/$sender_address_domain - -After finding a match in the DNS, the domain is placed in $dnslist_domain, and -then we check for a TXT record for an error message, and if found, save its -value in $dnslist_text. We also cache everything in a tree, to optimize -multiple lookups. - -The TXT record is normally looked up in the same domain as the A record, but -when many lists are combined in a single DNS domain, this will not be a very -specific message. It is possible to specify a different domain for looking up -TXT records; this is given before the main domain, comma-separated. For -example: - - dnslists = http.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.2 : \ - socks.dnsbl.sorbs.net,dnsbl.sorbs.net=127.0.0.3 - -The caching ensures that only one lookup in dnsbl.sorbs.net is done. - -Note: an address for testing RBL is 192.203.178.39 -Note: an address for testing DUL is 192.203.178.4 -Note: a domain for testing RFCI is example.tld.dsn.rfc-ignorant.org - -Arguments: - where the acl type - listptr the domain/address/data list - log_msgptr log message on error - -Returns: OK successful lookup (i.e. the address is on the list), or - lookup deferred after +include_unknown - FAIL name not found, or no data found for the given type, or - lookup deferred after +exclude_unknown (default) - DEFER lookup failure, if +defer_unknown was set -*/ - -int -verify_check_dnsbl(int where, const uschar ** listptr, uschar ** log_msgptr) -{ -int sep = 0; -int defer_return = FAIL; -const uschar *list = *listptr; -uschar *domain; -uschar revadd[128]; /* Long enough for IPv6 address */ - -/* Indicate that the inverted IP address is not yet set up */ - -revadd[0] = 0; - -/* In case this is the first time the DNS resolver is being used. */ - -dns_init(FALSE, FALSE, FALSE); /*XXX dnssec? */ - -/* Loop through all the domains supplied, until something matches */ - -while ((domain = string_nextinlist(&list, &sep, NULL, 0))) - { - int rc; - BOOL bitmask = FALSE; - int match_type = 0; - uschar *domain_txt; - uschar *comma; - uschar *iplist; - uschar *key; - - HDEBUG(D_dnsbl) debug_printf("dnslists check: %s\n", domain); - - /* Deal with special values that change the behaviour on defer */ - - if (domain[0] == '+') - { - if (strcmpic(domain, US"+include_unknown") == 0) defer_return = OK; - else if (strcmpic(domain, US"+exclude_unknown") == 0) defer_return = FAIL; - else if (strcmpic(domain, US"+defer_unknown") == 0) defer_return = DEFER; - else - log_write(0, LOG_MAIN|LOG_PANIC, "unknown item in dnslist (ignored): %s", - domain); - continue; - } - - /* See if there's explicit data to be looked up */ - - if ((key = Ustrchr(domain, '/'))) *key++ = 0; - - /* See if there's a list of addresses supplied after the domain name. This is - introduced by an = or a & character; if preceded by = we require all matches - and if preceded by ! we invert the result. */ - - if (!(iplist = Ustrchr(domain, '='))) - { - bitmask = TRUE; - iplist = Ustrchr(domain, '&'); - } - - if (iplist) /* Found either = or & */ - { - if (iplist > domain && iplist[-1] == '!') /* Handle preceding ! */ - { - match_type |= MT_NOT; - iplist[-1] = 0; - } - - *iplist++ = 0; /* Terminate domain, move on */ - - /* If we found = (bitmask == FALSE), check for == or =& */ - - if (!bitmask && (*iplist == '=' || *iplist == '&')) - { - bitmask = *iplist++ == '&'; - match_type |= MT_ALL; - } - } - - - /* If there is a comma in the domain, it indicates that a second domain for - looking up TXT records is provided, before the main domain. Otherwise we must - set domain_txt == domain. */ - - domain_txt = domain; - if ((comma = Ustrchr(domain, ','))) - { - *comma++ = 0; - domain = comma; - } - - /* Check that what we have left is a sensible domain name. There is no reason - why these domains should in fact use the same syntax as hosts and email - domains, but in practice they seem to. However, there is little point in - actually causing an error here, because that would no doubt hold up incoming - mail. Instead, I'll just log it. */ - - for (uschar * s = domain; *s; s++) - if (!isalnum(*s) && *s != '-' && *s != '.' && *s != '_') - { - log_write(0, LOG_MAIN, "dnslists domain \"%s\" contains " - "strange characters - is this right?", domain); - break; - } - - /* Check the alternate domain if present */ - - if (domain_txt != domain) for (uschar * s = domain_txt; *s; s++) - if (!isalnum(*s) && *s != '-' && *s != '.' && *s != '_') - { - log_write(0, LOG_MAIN, "dnslists domain \"%s\" contains " - "strange characters - is this right?", domain_txt); - break; - } - - /* If there is no key string, construct the query by adding the domain name - onto the inverted host address, and perform a single DNS lookup. */ - - if (!key) - { - if (where == ACL_WHERE_NOTSMTP_START || where == ACL_WHERE_NOTSMTP) - { - *log_msgptr = string_sprintf - ("cannot test auto-keyed dnslists condition in %s ACL", - acl_wherenames[where]); - return ERROR; - } - if (!sender_host_address) return FAIL; /* can never match */ - if (revadd[0] == 0) invert_address(revadd, sender_host_address); - rc = one_check_dnsbl(domain, domain_txt, sender_host_address, revadd, - iplist, bitmask, match_type, defer_return); - if (rc == OK) - { - dnslist_domain = string_copy(domain_txt); - dnslist_matched = string_copy(sender_host_address); - HDEBUG(D_dnsbl) debug_printf("=> that means %s is listed at %s\n", - sender_host_address, dnslist_domain); - } - if (rc != FAIL) return rc; /* OK or DEFER */ - } - - /* If there is a key string, it can be a list of domains or IP addresses to - be concatenated with the main domain. */ - - else - { - int keysep = 0; - BOOL defer = FALSE; - uschar *keydomain; - uschar keyrevadd[128]; - - while ((keydomain = string_nextinlist(CUSS &key, &keysep, NULL, 0))) - { - uschar *prepend = keydomain; - - if (string_is_ip_address(keydomain, NULL) != 0) - { - invert_address(keyrevadd, keydomain); - prepend = keyrevadd; - } - - rc = one_check_dnsbl(domain, domain_txt, keydomain, prepend, iplist, - bitmask, match_type, defer_return); - if (rc == OK) - { - dnslist_domain = string_copy(domain_txt); - dnslist_matched = string_copy(keydomain); - HDEBUG(D_dnsbl) debug_printf("=> that means %s is listed at %s\n", - keydomain, dnslist_domain); - return OK; - } - - /* If the lookup deferred, remember this fact. We keep trying the rest - of the list to see if we get a useful result, and if we don't, we return - DEFER at the end. */ - - if (rc == DEFER) defer = TRUE; - } /* continue with next keystring domain/address */ - - if (defer) return DEFER; - } - } /* continue with next dnsdb outer domain */ - -return FAIL; -} - - - /**************************************************** Verify a local user account for quota sufficiency ****************************************************/