/* * This program is free software; you can redistribute it and/or modify * it under the terms of either: * * a) The GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1, or (at your option) any * later version, * * OR * * b) The two-clause BSD license. * * These licenses can be found with the distribution in the file LICENSES */ #include "spf_sys_config.h" #ifdef STDC_HEADERS # include /* stdin / stdout */ # include /* malloc / free */ #endif #ifdef HAVE_STRING_H # include /* strstr / strdup */ #else # ifdef HAVE_STRINGS_H # include /* strstr / strdup */ # endif #endif #ifdef HAVE_MEMORY_H #include #endif #if TIME_WITH_SYS_TIME # include # include #else # if HAVE_SYS_TIME_H # include # else # include # endif #endif #ifdef HAVE_NETDB_H # include #endif #ifdef HAVE_PTHREAD_H # include #endif #include "spf.h" #include "spf_dns.h" #include "spf_internal.h" #include "spf_dns_internal.h" #include "spf_dns_cache.h" /** * @file * * Implements a simple cache using a list hash. There is no reclaim * list, since GNU malloc has clue. * * This original description from Wayne is no longer true: * * This is really little more than a proof-of-concept cache. * * The cache size is fixed and uses the CRC-32 function as a hash * generator. Little is done about hash collisions, no alternate hash * functions, no buckets, no linked lists, etc. There is a small * reclaim list and if you add multiple DNS cache layers of different * sizes you get slightly different hash functions. (The CRC-32 * function was chosen because I had a copy handy, it is pretty fast, * and single bit changes are guarenteed to give a different hash. * So, mx1.foo.com and mx2.foo.com will not collide) */ typedef struct _SPF_dns_cache_bucket_t { struct _SPF_dns_cache_bucket_t *next; SPF_dns_rr_t *rr; } SPF_dns_cache_bucket_t; typedef struct { SPF_dns_cache_bucket_t **cache; int cache_size; pthread_mutex_t cache_lock; int hash_mask; int max_hash_len; #if 0 int hit; int miss; #endif time_t min_ttl; time_t err_ttl; time_t txt_ttl; time_t rdns_ttl; int conserve_cache; } SPF_dns_cache_config_t; static inline SPF_dns_cache_config_t *SPF_voidp2spfhook( void *hook ) { return (SPF_dns_cache_config_t *)hook; } static inline void *SPF_spfhook2voidp( SPF_dns_cache_config_t *spfhook ) { return (void *)spfhook; } /* ** calculate CRC-32 stuff. */ /* * COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or * code or tables extracted from it, as desired without restriction. * * First, the polynomial itself and its table of feedback terms. The * polynomial is * X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0 * * Note that we take it "backwards" and put the highest-order term in * the lowest-order bit. The X^32 term is "implied"; the LSB is the * X^31 term, etc. The X^0 term (usually shown as "+1") results in * the MSB being 1 * * Note that the usual hardware shift register implementation, which * is what we're using (we're merely optimizing it by doing eight-bit * chunks at a time) shifts bits into the lowest-order term. In our * implementation, that means shifting towards the right. Why do we * do it this way? Because the calculated CRC must be transmitted in * order from highest-order term to lowest-order term. UARTs transmit * characters in order from LSB to MSB. By storing the CRC this way * we hand it to the UART in the order low-byte to high-byte; the UART * sends each low-bit to hight-bit; and the result is transmission bit * by bit from highest- to lowest-order term without requiring any bit * shuffling on our part. Reception works similarly * * The feedback terms table consists of 256, 32-bit entries. Notes * * The table can be generated at runtime if desired; code to do so * is shown later. It might not be obvious, but the feedback * terms simply represent the results of eight shift/xor opera * tions for all combinations of data and CRC register values * * The values must be right-shifted by eight bits by the "updcrc * logic; the shift must be unsigned (bring in zeroes). On some * hardware you could probably optimize the shift in assembler by * using byte-swap instructions * polynomial $edb88320 */ const unsigned int crc_32_tab[256] = { 0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L, 0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L, 0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L, 0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL, 0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L, 0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L, 0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L, 0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL, 0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L, 0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL, 0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L, 0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L, 0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L, 0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL, 0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL, 0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L, 0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL, 0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L, 0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L, 0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L, 0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL, 0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L, 0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L, 0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL, 0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L, 0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L, 0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L, 0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L, 0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L, 0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL, 0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL, 0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L, 0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L, 0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL, 0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL, 0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L, 0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL, 0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L, 0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL, 0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L, 0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL, 0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L, 0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L, 0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL, 0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L, 0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L, 0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L, 0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L, 0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L, 0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L, 0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL, 0x2d02ef8dL }; static inline int crc32str(unsigned int accum, const char *str, int max_hash_len) { for( ; *str != '\0' && max_hash_len > 0; str++ ) { if ( *str == '.' ) continue; accum = crc_32_tab[ (unsigned char)accum ^ (unsigned char)*str ] ^ (unsigned char)(accum >> 8); max_hash_len--; } return accum; } // #define hash(h,s,a) (crc32str(a,s,h->max_hash_len) & (h->hash_mask)) #define hash(h,s,a) crc32str(a,s,h->max_hash_len) /* This must be called with the lock held. */ static SPF_dns_cache_bucket_t * SPF_dns_cache_bucket_find(SPF_dns_cache_config_t *spfhook, const char *domain, ns_type rr_type, int idx) { SPF_dns_cache_bucket_t *bucket; SPF_dns_cache_bucket_t *prev; SPF_dns_rr_t *rr; time_t now; bucket = spfhook->cache[idx]; prev = NULL; time(&now); while (bucket != NULL) { rr = bucket->rr; if (rr->utc_ttl < now) { /* Unlink the bucket. */ if (prev != NULL) prev->next = bucket->next; else spfhook->cache[idx] = bucket->next; /* Free the bucket. */ if (bucket->rr) SPF_dns_rr_free(bucket->rr); free(bucket); /* Set iterator back one step. */ bucket = prev; /* Might be NULL */ } else if (rr->rr_type != rr_type) { /* Types differ */ } else if (strcmp(rr->domain, domain) != 0) { /* Domains differ */ } else { /* Move the bucket to the top of the chain. */ if (prev != NULL) { prev->next = bucket->next; bucket->next = spfhook->cache[idx]; spfhook->cache[idx] = bucket; } return bucket; } prev = bucket; /* Might be NULL */ if (bucket == NULL) /* After an unlink */ bucket = spfhook->cache[idx]; else bucket = bucket->next; } return NULL; } /* This must be called with the lock held. */ static SPF_errcode_t SPF_dns_cache_bucket_add(SPF_dns_cache_config_t *spfhook, SPF_dns_rr_t *rr, int idx) { SPF_dns_cache_bucket_t *bucket; bucket = (SPF_dns_cache_bucket_t *) malloc(sizeof(SPF_dns_cache_bucket_t)); if (! bucket) return SPF_E_NO_MEMORY; bucket->next = spfhook->cache[idx]; spfhook->cache[idx] = bucket; bucket->rr = rr; return SPF_E_SUCCESS; } /** * Patches up an rr for insertion into the cache. */ static SPF_errcode_t SPF_dns_cache_rr_fixup(SPF_dns_cache_config_t *spfhook, SPF_dns_rr_t *cached_rr, const char *domain, ns_type rr_type) { char *p; /* make sure the RR has enough data to be useful for caching */ if (cached_rr->rr_type == ns_t_any) cached_rr->rr_type = rr_type; /* XXX I'm still not sure about this bit. */ if (cached_rr->domain == NULL || cached_rr->domain[0] != '\0') { char *new_domain; size_t new_len = strlen(domain) + 1; if (cached_rr->domain_buf_len < new_len) { new_domain = realloc(cached_rr->domain, new_len); if (new_domain == NULL) return SPF_E_NO_MEMORY; cached_rr->domain = new_domain; cached_rr->domain_buf_len = new_len; } strcpy(cached_rr->domain, domain); } /* set up the ttl values */ if ( cached_rr->ttl < spfhook->min_ttl ) cached_rr->ttl = spfhook->min_ttl; if ( cached_rr->ttl < spfhook->txt_ttl && cached_rr->rr_type == ns_t_txt ) cached_rr->ttl = spfhook->txt_ttl; if ( cached_rr->ttl < spfhook->err_ttl && cached_rr->herrno != NETDB_SUCCESS ) cached_rr->ttl = spfhook->err_ttl; if ( cached_rr->ttl < spfhook->rdns_ttl ) { p = strstr( cached_rr->domain, ".arpa" ); if ( p && p[ sizeof( ".arpa" )-1 ] == '\0' ) cached_rr->ttl = spfhook->rdns_ttl; } cached_rr->utc_ttl = cached_rr->ttl + time(NULL); return SPF_E_SUCCESS; } /** * Can return NULL on out-of-memory condition. */ static SPF_dns_rr_t * SPF_dns_cache_lookup(SPF_dns_server_t *spf_dns_server, const char *domain, ns_type rr_type, int should_cache) { SPF_dns_cache_config_t *spfhook; SPF_dns_cache_bucket_t *bucket; SPF_dns_rr_t *cached_rr; SPF_dns_rr_t *rr; int idx; spfhook = SPF_voidp2spfhook(spf_dns_server->hook); /* max_hash_len and cache_size are constant, so this be done * outside the lock. */ idx = hash(spfhook, domain, 0 /* spfhook->hash_mask+rr_type */); idx &= (spfhook->cache_size - 1); pthread_mutex_lock(&(spfhook->cache_lock)); bucket = SPF_dns_cache_bucket_find(spfhook, domain, rr_type, idx); if (bucket != NULL) { if (bucket->rr != NULL) { if (SPF_dns_rr_dup(&rr, bucket->rr) == SPF_E_SUCCESS) { pthread_mutex_unlock(&(spfhook->cache_lock)); return rr; } else if (rr != NULL) { SPF_dns_rr_free(rr); /* Within the lock. :-( */ } } } /* Make sure we don't hang onto this outside the lock. * idx is presumably safe. */ bucket = NULL; pthread_mutex_unlock(&(spfhook->cache_lock)); if (!spf_dns_server->layer_below) return SPF_dns_rr_new_nxdomain(spf_dns_server, domain); rr = SPF_dns_lookup( spf_dns_server->layer_below, domain, rr_type, should_cache ); if (spfhook->conserve_cache && !should_cache) return rr; pthread_mutex_lock(&(spfhook->cache_lock)); if (SPF_dns_rr_dup(&cached_rr, rr) == SPF_E_SUCCESS) { if (SPF_dns_cache_rr_fixup(spfhook, cached_rr, domain, rr_type) == SPF_E_SUCCESS){ if (SPF_dns_cache_bucket_add(spfhook, cached_rr, idx) == SPF_E_SUCCESS) { pthread_mutex_unlock(&(spfhook->cache_lock)); return rr; } } } pthread_mutex_unlock(&(spfhook->cache_lock)); if (cached_rr) SPF_dns_rr_free(cached_rr); return rr; } static void SPF_dns_cache_free( SPF_dns_server_t *spf_dns_server ) { SPF_dns_cache_config_t *spfhook; SPF_dns_cache_bucket_t *bucket; SPF_dns_cache_bucket_t *prev; int i; SPF_ASSERT_NOTNULL(spf_dns_server); spfhook = SPF_voidp2spfhook( spf_dns_server->hook ); if ( spfhook ) { pthread_mutex_lock(&(spfhook->cache_lock)); if (spfhook->cache) { for( i = 0; i < spfhook->cache_size; i++ ) { bucket = spfhook->cache[i]; while (bucket != NULL) { prev = bucket; bucket = bucket->next; /* Free the bucket. */ if (prev->rr) SPF_dns_rr_free(prev->rr); free(prev); } } free(spfhook->cache); spfhook->cache = NULL; } pthread_mutex_unlock(&(spfhook->cache_lock)); /* * There is a risk that something might grab the mutex * here and try to look things up and try to resolve * stuff from a mashed cache it might happen but that's * what you get for trying to simultaneously free and * use a resource destroy will then return EBUSY but * it'll probably segfault so there ain't much to be * done really. */ pthread_mutex_destroy(&(spfhook->cache_lock)); free(spfhook); } free(spf_dns_server); } SPF_dns_server_t * SPF_dns_cache_new(SPF_dns_server_t *layer_below, const char *name, int debug, int cache_bits) { SPF_dns_server_t *spf_dns_server; SPF_dns_cache_config_t *spfhook; SPF_ASSERT_NOTNULL(layer_below); if ( cache_bits < 1 || cache_bits > 16 ) SPF_error( "cache bits out of range (1..16)." ); spf_dns_server = malloc(sizeof(SPF_dns_server_t)); if (spf_dns_server == NULL) return NULL; memset(spf_dns_server, 0, sizeof(SPF_dns_server_t)); spf_dns_server->hook = malloc(sizeof(SPF_dns_cache_config_t)); if (spf_dns_server->hook == NULL) { free(spf_dns_server); return NULL; } memset(spf_dns_server->hook, 0, sizeof(SPF_dns_cache_config_t)); if (name == NULL) name = "cache"; spf_dns_server->destroy = SPF_dns_cache_free; spf_dns_server->lookup = SPF_dns_cache_lookup; spf_dns_server->get_spf = NULL; spf_dns_server->get_exp = NULL; spf_dns_server->add_cache = NULL; spf_dns_server->layer_below = layer_below; spf_dns_server->name = name; spf_dns_server->debug = debug; spfhook = SPF_voidp2spfhook( spf_dns_server->hook ); spfhook->cache_size = 1 << cache_bits; spfhook->hash_mask = spfhook->cache_size - 1; spfhook->max_hash_len = cache_bits > 4 ? cache_bits * 2 : 8; spfhook->cache = calloc(spfhook->cache_size, sizeof(*spfhook->cache)); #if 0 spfhook->hit = 0; spfhook->miss = 0; #endif spfhook->min_ttl = 30; spfhook->err_ttl = 30*60; spfhook->txt_ttl = 30*60; spfhook->rdns_ttl = 30*60; spfhook->conserve_cache = cache_bits < 12; if (spfhook->cache == NULL) { free(spfhook); free(spf_dns_server); return NULL; } pthread_mutex_init(&(spfhook->cache_lock),NULL); return spf_dns_server; } void SPF_dns_cache_set_ttl( SPF_dns_server_t *spf_dns_server, time_t min_ttl, time_t err_ttl, time_t txt_ttl, time_t rdns_ttl ) { SPF_dns_cache_config_t *spfhook; SPF_ASSERT_NOTNULL(spf_dns_server); spfhook = SPF_voidp2spfhook( spf_dns_server->hook ); if (spfhook != NULL) { pthread_mutex_lock(&(spfhook->cache_lock)); spfhook->min_ttl = min_ttl; spfhook->err_ttl = err_ttl; spfhook->txt_ttl = txt_ttl; spfhook->rdns_ttl = rdns_ttl; pthread_mutex_unlock(&(spfhook->cache_lock)); } } void SPF_dns_set_conserve_cache( SPF_dns_server_t *spf_dns_server, int conserve_cache ) { SPF_dns_cache_config_t *spfhook; SPF_ASSERT_NOTNULL(spf_dns_server); spfhook = SPF_voidp2spfhook( spf_dns_server->hook ); /* This is a boolean and it doesn't matter if it * changes suddenly, thus no lock. */ if (spfhook != NULL) spfhook->conserve_cache = conserve_cache; }