/************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2015 */ /* See the file NOTICE for conditions of use and distribution. */ /* A set of functions to search databases in various formats. An open database is represented by a void * value which is returned from a lookup- specific "open" function. These are now all held in individual modules in the lookups subdirectory and the functions here form a generic interface. Caching is used to improve performance. Open files are cached until a tidyup function is called, and for each file the result of the last lookup is cached. However, if too many files are opened, some of those that are not in use have to be closed. Those open items that use real files are kept on a LRU chain to help with this. All the data is held in permanent store so as to be independent of the stacking pool that is reset from time to time. In fact, we use malloc'd store so that it can be freed when the caches are tidied up. It isn't actually clear whether this is a benefit or not, to be honest. */ #include "exim.h" /* Tree in which to cache open files until tidyup called. */ static tree_node *search_tree = NULL; /* Two-way chain of open databases that use real files. This is maintained in recently-used order for the purposes of closing the least recently used when too many files are open. */ static tree_node *open_top = NULL; static tree_node *open_bot = NULL; /* Count of open databases that use real files */ static int open_filecount = 0; /* Allow us to reset store used for lookups and lookup caching */ static void *search_reset_point = NULL; /************************************************* * Validate a plain lookup type name * *************************************************/ /* Only those names that are recognized and whose code is included in the binary give an OK response. Use a binary chop search now that the list has got so long. Arguments: name lookup type name - not necessarily zero terminated (e.g. dbm*) len length of the name Returns: +ve => valid lookup name; value is offset in lookup_list -ve => invalid name; message in search_error_message. */ int search_findtype(const uschar *name, int len) { int bot = 0; int top = lookup_list_count; while (top > bot) { int mid = (top + bot)/2; int c = Ustrncmp(name, lookup_list[mid]->name, len); /* If c == 0 we have matched the incoming name with the start of the search type name. However, some search types are substrings of others (e.g. nis and nisplus) so we need to check that the lengths are the same. The length of the type name cannot be shorter (else c would not be 0); if it is not equal it must be longer, and in that case, the incoming name comes before the name we are testing. By leaving c == 0 when the lengths are different, and doing a > 0 test below, this all falls out correctly. */ if (c == 0 && Ustrlen(lookup_list[mid]->name) == len) { if (lookup_list[mid]->find != NULL) return mid; search_error_message = string_sprintf("lookup type \"%.*s\" is not " "available (not in the binary - check buildtime LOOKUP configuration)", len, name); return -1; } if (c > 0) bot = mid + 1; else top = mid; } search_error_message = string_sprintf("unknown lookup type \"%.*s\"",len,name); return -1; } /************************************************* * Validate a full lookup type name * *************************************************/ /* This function recognizes the "partial-" prefix and also terminating * and *@ suffixes. Arguments: name the full lookup type name ptypeptr where to put the partial type after subtraction of 1024 or 2048: negative => no partial matching non-negative => minimum number of non-wild components ptypeaff where to put a pointer to the affix the affix is within name if supplied therein otherwise it's a literal string afflen the length of the affix starflags where to put the SEARCH_STAR and SEARCH_STARAT flags Returns: +ve => valid lookup name; value is offset in lookup_list -ve => invalid name; message in search_error_message. */ int search_findtype_partial(const uschar *name, int *ptypeptr, const uschar **ptypeaff, int *afflen, int *starflags) { int len, stype; int pv = -1; const uschar *ss = name; *starflags = 0; *ptypeaff = NULL; /* Check for a partial matching type. It must start with "partial", optionally followed by a sequence of digits. If this is followed by "-", the affix is the default "*." string. Otherwise we expect an affix in parentheses. Affixes are a limited number of characters, not including parens. */ if (Ustrncmp(name, "partial", 7) == 0) { ss += 7; if (isdigit (*ss)) { pv = 0; while (isdigit(*ss)) pv = pv*10 + *ss++ - '0'; } else pv = 2; /* Default number of wild components */ if (*ss == '(') { *ptypeaff = ++ss; while (ispunct(*ss) && *ss != ')') ss++; if (*ss != ')') goto BAD_TYPE; *afflen = ss++ - *ptypeaff; } else if (*ss++ == '-') { *ptypeaff = US "*."; *afflen = 2; } else { BAD_TYPE: search_error_message = string_sprintf("format error in lookup type \"%s\"", name); return -1; } } /* Now we are left with a lookup name, possibly followed by * or *@. */ len = Ustrlen(ss); if (len >= 2 && Ustrncmp(ss + len - 2, "*@", 2) == 0) { *starflags |= SEARCH_STARAT; len -= 2; } else if (len >= 1 && ss[len-1] == '*') { *starflags |= SEARCH_STAR; len--; } /* Check for the individual search type. Only those that are actually in the binary are valid. For query-style types, "partial" and default types are erroneous. */ stype = search_findtype(ss, len); if (stype >= 0 && mac_islookup(stype, lookup_querystyle)) { if (pv >= 0) { search_error_message = string_sprintf("\"partial\" is not permitted " "for lookup type \"%s\"", ss); return -1; } if ((*starflags & (SEARCH_STAR|SEARCH_STARAT)) != 0) { search_error_message = string_sprintf("defaults using \"*\" or \"*@\" are " "not permitted for lookup type \"%s\"", ss); return -1; } } *ptypeptr = pv; return stype; } /************************************************* * Release cached resources * *************************************************/ /* When search_open is called it caches the "file" that it opens in search_tree. The name of the tree node is a concatenation of the search type with the file name. For query-style lookups, the file name is empty. Real files are normally closed only when this tidyup routine is called, typically at the end of sections of code where a number of lookups might occur. However, if too many files are open simultaneously, some get closed beforehand. They can't be removed from the tree. There is also a general tidyup function which is called for the lookup driver, if it exists. First, there is an internal, recursive subroutine. Argument: a pointer to a search_openfile tree node Returns: nothing */ static void tidyup_subtree(tree_node *t) { search_cache *c = (search_cache *)(t->data.ptr); if (t->left != NULL) tidyup_subtree(t->left); if (t->right != NULL) tidyup_subtree(t->right); if (c != NULL && c->handle != NULL && lookup_list[c->search_type]->close != NULL) lookup_list[c->search_type]->close(c->handle); } /* The external entry point Argument: none Returns: nothing */ void search_tidyup(void) { int i; int old_pool = store_pool; DEBUG(D_lookup) debug_printf("search_tidyup called\n"); /* Close individually each cached open file. */ store_pool = POOL_SEARCH; if (search_tree != NULL) { tidyup_subtree(search_tree); search_tree = NULL; } open_top = open_bot = NULL; open_filecount = 0; /* Call the general tidyup entry for any drivers that have one. */ for (i = 0; i < lookup_list_count; i++) if (lookup_list[i]->tidy != NULL) (lookup_list[i]->tidy)(); if (search_reset_point != NULL) store_reset(search_reset_point); search_reset_point = NULL; store_pool = old_pool; } /************************************************* * Open search database * *************************************************/ /* A mode, and lists of owners and groups, are passed over for checking in the cases where the database is one or more files. Return NULL, with a message pointed to by message, in cases of error. For search types that use a file or files, check up on the mode after opening. It is tempting to do a stat before opening the file, and use it as an existence check. However, doing that opens a small security loophole in that the status could be changed before the file is opened. Can't quite see what problems this might lead to, but you can't be too careful where security is concerned. Fstat() on an open file can normally be expected to succeed, but there are some NFS states where it does not. There are two styles of query: (1) in the "single-key+file" style, a single key string and a file name are given, for example, for linear searches, DBM files, or for NIS. (2) In the "query" style, no "filename" is given; instead just a single query string is passed. This applies to multiple-key lookup types such as NIS+. Before opening, scan the tree of cached files to see if this file is already open for the correct search type. If so, return the saved handle. If not, put the handle in the tree for possible subsequent use. See search_tidyup above for closing all the cached files. A count of open databases which use real files is maintained, and if this gets too large, we have to close a cached file. Its entry remains in the tree, but is marked closed. Arguments: filename the name of the file for single-key+file style lookups, NULL for query-style lookups search_type the type of search required modemask if a real single file is used, this specifies mode bits that must not be set; otherwise it is ignored owners if a real single file is used, this specifies the possible owners of the file; otherwise it is ignored owngroups if a real single file is used, this specifies the possible group owners of the file; otherwise it is ignored Returns: an identifying handle for the open database; this is the pointer to the tree block in the cache of open files; return NULL on open failure, with a message in search_error_message */ void * search_open(uschar *filename, int search_type, int modemask, uid_t *owners, gid_t *owngroups) { void *handle; tree_node *t; search_cache *c; lookup_info *lk = lookup_list[search_type]; uschar keybuffer[256]; int old_pool = store_pool; /* Change to the search store pool and remember our reset point */ store_pool = POOL_SEARCH; if (search_reset_point == NULL) search_reset_point = store_get(0); DEBUG(D_lookup) debug_printf("search_open: %s \"%s\"\n", lk->name, (filename == NULL)? US"NULL" : filename); /* See if we already have this open for this type of search, and if so, pass back the tree block as the handle. The key for the tree node is the search type plus '0' concatenated with the file name. There may be entries in the tree with closed files if a lot of files have been opened. */ sprintf(CS keybuffer, "%c%.254s", search_type + '0', (filename == NULL)? US"" : filename); if ((t = tree_search(search_tree, keybuffer)) != NULL) { c = (search_cache *)(t->data.ptr); if (c->handle != NULL) { DEBUG(D_lookup) debug_printf(" cached open\n"); store_pool = old_pool; return t; } DEBUG(D_lookup) debug_printf(" cached closed\n"); } /* Otherwise, we need to open the file or database - each search type has its own code, which is now split off into separately compiled modules. Before doing this, if the search type is one that uses real files, check on the number that we are holding open in the cache. If the limit is reached, close the least recently used one. */ if (lk->type == lookup_absfile && open_filecount >= lookup_open_max) { if (open_bot == NULL) log_write(0, LOG_MAIN|LOG_PANIC, "too many lookups open, but can't find " "one to close"); else { search_cache *c = (search_cache *)(open_bot->data.ptr); DEBUG(D_lookup) debug_printf("Too many lookup files open\n closing %s\n", open_bot->name); open_bot = c->up; if (open_bot != NULL) ((search_cache *)(open_bot->data.ptr))->down = NULL; else open_top = NULL; ((lookup_list[c->search_type])->close)(c->handle); c->handle = NULL; open_filecount--; } } /* If opening is successful, call the file-checking function if there is one, and if all is still well, enter the open database into the tree. */ handle = (lk->open)(filename, &search_error_message); if (handle == NULL) { store_pool = old_pool; return NULL; } if (lk->check != NULL && !lk->check(handle, filename, modemask, owners, owngroups, &search_error_message)) { lk->close(handle); store_pool = old_pool; return NULL; } /* If this is a search type that uses real files, keep count. */ if (lk->type == lookup_absfile) open_filecount++; /* If we found a previously opened entry in the tree, re-use it; otherwise insert a new entry. On re-use, leave any cached lookup data and the lookup count alone. */ if (t == NULL) { t = store_get(sizeof(tree_node) + Ustrlen(keybuffer)); t->data.ptr = c = store_get(sizeof(search_cache)); c->item_cache = NULL; Ustrcpy(t->name, keybuffer); tree_insertnode(&search_tree, t); } else c = t->data.ptr; c->handle = handle; c->search_type = search_type; c->up = c->down = NULL; store_pool = old_pool; return t; } /************************************************* * Internal function: Find one item in database * *************************************************/ /* The answer is always put into dynamic store. The last lookup for each handle is cached. Arguments: handle the handle from search_open; points to tree node filename the filename that was handed to search_open, or NULL for query-style searches keystring the keystring for single-key+file lookups, or the querystring for query-style lookups Returns: a pointer to a dynamic string containing the answer, or NULL if the query failed or was deferred; in the latter case, search_find_defer is set TRUE; after an unusual failure, there may be a message in search_error_message. */ static uschar * internal_search_find(void *handle, uschar *filename, uschar *keystring) { tree_node *t = (tree_node *)handle; search_cache *c = (search_cache *)(t->data.ptr); expiring_data *e; uschar *data = NULL; int search_type = t->name[0] - '0'; int old_pool = store_pool; /* Lookups that return DEFER may not always set an error message. So that the callers don't have to test for NULL, set an empty string. */ search_error_message = US""; search_find_defer = FALSE; DEBUG(D_lookup) debug_printf("internal_search_find: file=\"%s\"\n " "type=%s key=\"%s\"\n", filename, lookup_list[search_type]->name, keystring); /* Insurance. If the keystring is empty, just fail. */ if (keystring[0] == 0) return NULL; /* Use the special store pool for search data */ store_pool = POOL_SEARCH; /* Look up the data for the key, unless it is already in the cache for this file. No need to check c->item_cache for NULL, tree_search will do so. */ if ( (t = tree_search(c->item_cache, keystring)) && (!(e = t->data.ptr)->expiry || e->expiry > time(NULL)) ) { /* Data was in the cache already; set the pointer from the tree node */ data = e->ptr; DEBUG(D_lookup) debug_printf("cached data used for lookup of %s%s%s\n", keystring, filename ? US"\n in " : US"", filename ? filename : US""); } else { uint do_cache = UINT_MAX; int keylength = Ustrlen(keystring); DEBUG(D_lookup) { if (t) debug_printf("cached data found but past valid time; "); debug_printf("%s lookup required for %s%s%s\n", filename ? US"file" : US"database", keystring, filename ? US"\n in " : US"", filename ? filename : US""); } /* Call the code for the different kinds of search. DEFER is handled like FAIL, except that search_find_defer is set so the caller can distinguish if necessary. */ if (lookup_list[search_type]->find(c->handle, filename, keystring, keylength, &data, &search_error_message, &do_cache) == DEFER) search_find_defer = TRUE; /* A record that has been found is now in data, which is either NULL or points to a bit of dynamic store. Cache the result of the lookup if caching is permitted. Lookups can disable caching, when they did something that changes their data. The mysql and pgsql lookups do this when an UPDATE/INSERT query was executed. */ else if (do_cache) { int len = keylength + 1; if (t) /* Previous, out-of-date cache entry. Update with the */ { /* new result and forget the old one */ e->expiry = do_cache == UINT_MAX ? 0 : time(NULL)+do_cache; e->ptr = data; } else { e = store_get(sizeof(expiring_data) + sizeof(tree_node) + len); e->expiry = do_cache == UINT_MAX ? 0 : time(NULL)+do_cache; e->ptr = data; t = (tree_node *)(e+1); memcpy(t->name, keystring, len); t->data.ptr = e; tree_insertnode(&c->item_cache, t); } } /* If caching was disabled, empty the cache tree. We just set the cache pointer to NULL here, because we cannot release the store at this stage. */ else { DEBUG(D_lookup) debug_printf("lookup forced cache cleanup\n"); c->item_cache = NULL; } } DEBUG(D_lookup) { if (data) debug_printf("lookup yielded: %s\n", data); else if (search_find_defer) debug_printf("lookup deferred: %s\n", search_error_message); else debug_printf("lookup failed\n"); } /* Return it in new dynamic store in the regular pool */ store_pool = old_pool; return data ? string_copy(data) : NULL; } /************************************************* * Find one item in database, possibly wildcarded * *************************************************/ /* This function calls the internal function above; once only if there is no partial matching, but repeatedly when partial matching is requested. Arguments: handle the handle from search_open filename the filename that was handed to search_open, or NULL for query-style searches keystring the keystring for single-key+file lookups, or the querystring for query-style lookups partial -1 means no partial matching; otherwise it's the minimum number of components; affix the affix string for partial matching affixlen the length of the affix string starflags SEARCH_STAR and SEARCH_STARAT flags expand_setup pointer to offset for setting up expansion strings; don't do any if < 0 Returns: a pointer to a dynamic string containing the answer, or NULL if the query failed or was deferred; in the latter case, search_find_defer is set TRUE */ uschar * search_find(void *handle, uschar *filename, uschar *keystring, int partial, const uschar *affix, int affixlen, int starflags, int *expand_setup) { tree_node *t = (tree_node *)handle; BOOL set_null_wild = FALSE; uschar *yield; DEBUG(D_lookup) { if (partial < 0) affixlen = 99; /* So that "NULL" prints */ debug_printf("search_find: file=\"%s\"\n key=\"%s\" " "partial=%d affix=%.*s starflags=%x\n", (filename == NULL)? US"NULL" : filename, keystring, partial, affixlen, affix, starflags); } /* Arrange to put this database at the top of the LRU chain if it is a type that opens real files. */ if (open_top != (tree_node *)handle && lookup_list[t->name[0]-'0']->type == lookup_absfile) { search_cache *c = (search_cache *)(t->data.ptr); tree_node *up = c->up; tree_node *down = c->down; /* Cut it out of the list. A newly opened file will a NULL up pointer. Otherwise there will be a non-NULL up pointer, since we checked above that this block isn't already at the top of the list. */ if (up != NULL) { ((search_cache *)(up->data.ptr))->down = down; if (down != NULL) ((search_cache *)(down->data.ptr))->up = up; else open_bot = up; } /* Now put it at the head of the list. */ c->up = NULL; c->down = open_top; if (open_top == NULL) open_bot = t; else ((search_cache *)(open_top->data.ptr))->up = t; open_top = t; } DEBUG(D_lookup) { tree_node *t = open_top; debug_printf("LRU list:\n"); while (t != NULL) { search_cache *c = (search_cache *)(t->data.ptr); debug_printf(" %s\n", t->name); if (t == open_bot) debug_printf(" End\n"); t = c->down; } } /* First of all, try to match the key string verbatim. If matched a complete entry but could have been partial, flag to set up variables. */ yield = internal_search_find(handle, filename, keystring); if (search_find_defer) return NULL; if (yield != NULL) { if (partial >= 0) set_null_wild = TRUE; } /* Not matched a complete entry; handle partial lookups, but only if the full search didn't defer. Don't use string_sprintf() to construct the initial key, just in case the original key is too long for the string_sprintf() buffer (it *has* happened!). The case of a zero-length affix has to be treated specially. */ else if (partial >= 0) { int len = Ustrlen(keystring); uschar *keystring2; /* Try with the affix on the front, except for a zero-length affix */ if (affixlen == 0) keystring2 = keystring; else { keystring2 = store_get(len + affixlen + 1); Ustrncpy(keystring2, affix, affixlen); Ustrcpy(keystring2 + affixlen, keystring); DEBUG(D_lookup) debug_printf("trying partial match %s\n", keystring2); yield = internal_search_find(handle, filename, keystring2); if (search_find_defer) return NULL; } /* The key in its entirety did not match a wild entry; try chopping off leading components. */ if (yield == NULL) { int dotcount = 0; uschar *keystring3 = keystring2 + affixlen; uschar *s = keystring3; while (*s != 0) if (*s++ == '.') dotcount++; while (dotcount-- >= partial) { while (*keystring3 != 0 && *keystring3 != '.') keystring3++; /* If we get right to the end of the string (which will be the last time through this loop), we've failed if the affix is null. Otherwise do one last lookup for the affix itself, but if it is longer than 1 character, remove the last character if it is ".". */ if (*keystring3 == 0) { if (affixlen < 1) break; if (affixlen > 1 && affix[affixlen-1] == '.') affixlen--; Ustrncpy(keystring2, affix, affixlen); keystring2[affixlen] = 0; keystring3 = keystring2; } else { keystring3 -= affixlen - 1; if (affixlen > 0) Ustrncpy(keystring3, affix, affixlen); } DEBUG(D_lookup) debug_printf("trying partial match %s\n", keystring3); yield = internal_search_find(handle, filename, keystring3); if (search_find_defer) return NULL; if (yield != NULL) { /* First variable is the wild part; second is the fixed part. Take care to get it right when keystring3 is just "*". */ if (expand_setup != NULL && *expand_setup >= 0) { int fixedlength = Ustrlen(keystring3) - affixlen; int wildlength = Ustrlen(keystring) - fixedlength - 1; *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = wildlength; *expand_setup += 1; expand_nstring[*expand_setup] = keystring + wildlength + 1; expand_nlength[*expand_setup] = (fixedlength < 0)? 0 : fixedlength; } break; } keystring3 += affixlen; } } else set_null_wild = TRUE; /* Matched a wild entry without any wild part */ } /* If nothing has been matched, but the option to look for "*@" is set, try replacing everthing to the left of @ by *. After a match, the wild part is set to the string to the left of the @. */ if (yield == NULL && (starflags & SEARCH_STARAT) != 0) { uschar *atat = Ustrrchr(keystring, '@'); if (atat != NULL && atat > keystring) { int savechar; savechar = *(--atat); *atat = '*'; DEBUG(D_lookup) debug_printf("trying default match %s\n", atat); yield = internal_search_find(handle, filename, atat); *atat = savechar; if (search_find_defer) return NULL; if (yield != NULL && expand_setup != NULL && *expand_setup >= 0) { *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = atat - keystring + 1; *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = 0; } } } /* If we still haven't matched anything, and the option to look for "*" is set, try that. If we do match, the first variable (the wild part) is the whole key, and the second is empty. */ if (yield == NULL && (starflags & (SEARCH_STAR|SEARCH_STARAT)) != 0) { DEBUG(D_lookup) debug_printf("trying to match *\n"); yield = internal_search_find(handle, filename, US"*"); if (yield != NULL && expand_setup != NULL && *expand_setup >= 0) { *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = Ustrlen(keystring); *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = 0; } } /* If this was a potentially partial lookup, and we matched either a complete non-wild domain entry, or we matched a wild-carded entry without chopping off any of the domain components, set up the expansion variables (if required) so that the first one is empty, and the second one is the fixed part of the domain. The set_null_wild flag is set only when yield is not NULL. */ if (set_null_wild && expand_setup != NULL && *expand_setup >= 0) { *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = 0; *expand_setup += 1; expand_nstring[*expand_setup] = keystring; expand_nlength[*expand_setup] = Ustrlen(keystring); } return yield; } /* End of search.c */