Adding upstream version 3.7.10.upstream/3.7.10

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 624 insertions, 0 deletions

diff --git a/src/postscreen/postscreen_dnsbl.c b/src/postscreen/postscreen_dnsbl.c
new file mode 100644
index 0000000..7d9a5e9
--- /dev/null
+++ b/src/postscreen/postscreen_dnsbl.c
@@ -0,0 +1,624 @@
+/*++
+/* NAME
+/*	postscreen_dnsbl 3
+/* SUMMARY
+/*	postscreen DNSBL support
+/* SYNOPSIS
+/*	#include <postscreen.h>
+/*
+/*	void	psc_dnsbl_init(void)
+/*
+/*	int	psc_dnsbl_request(client_addr, callback, context)
+/*	char	*client_addr;
+/*	void	(*callback)(int, char *);
+/*	char	*context;
+/*
+/*	int	psc_dnsbl_retrieve(client_addr, dnsbl_name, dnsbl_index,
+/*					dnsbl_ttl)
+/*	char	*client_addr;
+/*	const char **dnsbl_name;
+/*	int	dnsbl_index;
+/*	int	*dnsbl_ttl;
+/* DESCRIPTION
+/*	This module implements preliminary support for DNSBL lookups.
+/*	Multiple requests for the same information are handled with
+/*	reference counts.
+/*
+/*	psc_dnsbl_init() initializes this module, and must be called
+/*	once before any of the other functions in this module.
+/*
+/*	psc_dnsbl_request() requests a blocklist score for the
+/*	specified client IP address and increments the reference
+/*	count.  The request completes in the background. The client
+/*	IP address must be in inet_ntop(3) output format.  The
+/*	callback argument specifies a function that is called when
+/*	the requested result is available. The context is passed
+/*	on to the callback function. The callback should ignore its
+/*	first argument (it exists for compatibility with Postfix
+/*	generic event infrastructure).
+/*	The result value is the index for the psc_dnsbl_retrieve()
+/*	call.
+/*
+/*	psc_dnsbl_retrieve() retrieves the result score and reply
+/*	TTL requested with psc_dnsbl_request(), and decrements the
+/*	reference count. The reply TTL value is clamped to
+/*	postscreen_dnsbl_min_ttl and postscreen_dnsbl_max_ttl.  It
+/*	is an error to retrieve a score without requesting it first.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/socket.h>			/* AF_INET */
+#include <netinet/in.h>			/* inet_pton() */
+#include <arpa/inet.h>			/* inet_pton() */
+#include <stdio.h>			/* sscanf */
+#include <limits.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <argv.h>
+#include <htable.h>
+#include <events.h>
+#include <vstream.h>
+#include <connect.h>
+#include <split_at.h>
+#include <valid_hostname.h>
+#include <ip_match.h>
+#include <myaddrinfo.h>
+#include <stringops.h>
+
+/* Global library. */
+
+#include <mail_params.h>
+#include <mail_proto.h>
+
+/* Application-specific. */
+
+#include <postscreen.h>
+
+ /*
+  * Talking to the DNSBLOG service.
+  */
+static char *psc_dnsbl_service;
+
+ /*
+  * Per-DNSBL filters and weights.
+  * 
+  * The postscreen_dnsbl_sites parameter specifies zero or more DNSBL domains.
+  * We provide multiple access methods, one for quick iteration when sending
+  * queries to all DNSBL servers, and one for quick location when receiving a
+  * reply from one DNSBL server.
+  * 
+  * Each DNSBL domain can be specified more than once, each time with a
+  * different (filter, weight) pair. We group (filter, weight) pairs in a
+  * linked list under their DNSBL domain name. The list head has a reference
+  * to a "safe name" for the DNSBL, in case the name includes a password.
+  */
+static HTABLE *dnsbl_site_cache;	/* indexed by DNSBNL domain */
+static HTABLE_INFO **dnsbl_site_list;	/* flattened cache */
+
+typedef struct {
+    const char *safe_dnsbl;		/* from postscreen_dnsbl_reply_map */
+    struct PSC_DNSBL_SITE *first;	/* list of (filter, weight) tuples */
+} PSC_DNSBL_HEAD;
+
+typedef struct PSC_DNSBL_SITE {
+    char   *filter;			/* printable filter (default: null) */
+    char   *byte_codes;			/* encoded filter (default: null) */
+    int     weight;			/* reply weight (default: 1) */
+    struct PSC_DNSBL_SITE *next;	/* linked list */
+} PSC_DNSBL_SITE;
+
+ /*
+  * Per-client DNSBL scores.
+  * 
+  * Some SMTP clients make parallel connections. This can trigger parallel
+  * blocklist score requests when the pre-handshake delays of the connections
+  * overlap.
+  * 
+  * We combine requests for the same score under the client IP address in a
+  * single reference-counted entry. The reference count goes up with each
+  * request for a score, and it goes down with each score retrieval. Each
+  * score has one or more requestors that need to be notified when the result
+  * is ready, so that postscreen can terminate a pre-handshake delay when all
+  * pre-handshake tests are completed.
+  */
+static HTABLE *dnsbl_score_cache;	/* indexed by client address */
+
+typedef struct {
+    void    (*callback) (int, void *);	/* generic call-back routine */
+    void   *context;			/* generic call-back argument */
+} PSC_CALL_BACK_ENTRY;
+
+typedef struct {
+    const char *dnsbl_name;		/* DNSBL with largest contribution */
+    int     dnsbl_weight;		/* weight of largest contribution */
+    int     total;			/* combined allow+denylist score */
+    int     fail_ttl;			/* combined reply TTL */
+    int     pass_ttl;			/* combined reply TTL */
+    int     refcount;			/* score reference count */
+    int     pending_lookups;		/* nr of DNS requests in flight */
+    int     request_id;			/* duplicate suppression */
+    /* Call-back table support. */
+    int     index;			/* next table index */
+    int     limit;			/* last valid index */
+    PSC_CALL_BACK_ENTRY table[1];	/* actually a bunch */
+} PSC_DNSBL_SCORE;
+
+#define PSC_CALL_BACK_INIT(sp) do { \
+	(sp)->limit = 0; \
+	(sp)->index = 0; \
+    } while (0)
+
+#define PSC_CALL_BACK_INDEX_OF_LAST(sp) ((sp)->index - 1)
+
+#define PSC_CALL_BACK_CANCEL(sp, idx) do { \
+	PSC_CALL_BACK_ENTRY *_cb_; \
+	if ((idx) < 0 || (idx) >= (sp)->index) \
+	    msg_panic("%s: index %d must be >= 0 and < %d", \
+		      myname, (idx), (sp)->index); \
+	_cb_ = (sp)->table + (idx); \
+	event_cancel_timer(_cb_->callback, _cb_->context); \
+	_cb_->callback = 0; \
+	_cb_->context = 0; \
+    } while (0)
+
+#define PSC_CALL_BACK_EXTEND(hp, sp) do { \
+	if ((sp)->index >= (sp)->limit) { \
+	    int _count_ = ((sp)->limit ? (sp)->limit * 2 : 5); \
+	    (hp)->value = myrealloc((void *) (sp), sizeof(*(sp)) + \
+				    _count_ * sizeof((sp)->table)); \
+	    (sp) = (PSC_DNSBL_SCORE *) (hp)->value; \
+	    (sp)->limit = _count_; \
+	} \
+    } while (0)
+
+#define PSC_CALL_BACK_ENTER(sp, fn, ctx) do { \
+	PSC_CALL_BACK_ENTRY *_cb_ = (sp)->table + (sp)->index++; \
+	_cb_->callback = (fn); \
+	_cb_->context = (ctx); \
+    } while (0)
+
+#define PSC_CALL_BACK_NOTIFY(sp, ev) do { \
+	PSC_CALL_BACK_ENTRY *_cb_; \
+	for (_cb_ = (sp)->table; _cb_ < (sp)->table + (sp)->index; _cb_++) \
+	    if (_cb_->callback != 0) \
+		_cb_->callback((ev), _cb_->context); \
+    } while (0)
+
+#define PSC_NULL_EVENT	(0)
+
+ /*
+  * Per-request state.
+  * 
+  * This implementation stores the client IP address and DNSBL domain in the
+  * DNSBLOG query/reply stream. This simplifies code, and allows the DNSBLOG
+  * server to produce more informative logging.
+  */
+static VSTRING *reply_client;		/* client address in DNSBLOG reply */
+static VSTRING *reply_dnsbl;		/* domain in DNSBLOG reply */
+static VSTRING *reply_addr;		/* address list in DNSBLOG reply */
+
+/* psc_dnsbl_add_site - add DNSBL site information */
+
+static void psc_dnsbl_add_site(const char *site)
+{
+    const char *myname = "psc_dnsbl_add_site";
+    char   *saved_site = mystrdup(site);
+    VSTRING *byte_codes = 0;
+    PSC_DNSBL_HEAD *head;
+    PSC_DNSBL_SITE *new_site;
+    char    junk;
+    const char *weight_text;
+    char   *pattern_text;
+    int     weight;
+    HTABLE_INFO *ht;
+    char   *parse_err;
+    const char  *safe_dnsbl;
+
+    /*
+     * Parse the required DNSBL domain name, the optional reply filter and
+     * the optional reply weight factor.
+     */
+#define DO_GRIPE	1
+
+    /* Negative weight means allowlist. */
+    if ((weight_text = split_at(saved_site, '*')) != 0) {
+	if (sscanf(weight_text, "%d%c", &weight, &junk) != 1)
+	    msg_fatal("bad DNSBL weight factor \"%s\" in \"%s\"",
+		      weight_text, site);
+    } else {
+	weight = 1;
+    }
+    /* Reply filter. */
+    if ((pattern_text = split_at(saved_site, '=')) != 0) {
+	byte_codes = vstring_alloc(100);
+	if ((parse_err = ip_match_parse(byte_codes, pattern_text)) != 0)
+	    msg_fatal("bad DNSBL filter syntax: %s", parse_err);
+    }
+    if (valid_hostname(saved_site, DO_GRIPE) == 0)
+	msg_fatal("bad DNSBL domain name \"%s\" in \"%s\"",
+		  saved_site, site);
+
+    if (msg_verbose > 1)
+	msg_info("%s: \"%s\" -> domain=\"%s\" pattern=\"%s\" weight=%d",
+		 myname, site, saved_site, pattern_text ? pattern_text :
+		 "null", weight);
+
+    /*
+     * Look up or create the (filter, weight) list head for this DNSBL domain
+     * name.
+     */
+    if ((head = (PSC_DNSBL_HEAD *)
+	 htable_find(dnsbl_site_cache, saved_site)) == 0) {
+	head = (PSC_DNSBL_HEAD *) mymalloc(sizeof(*head));
+	ht = htable_enter(dnsbl_site_cache, saved_site, (void *) head);
+	/* Translate the DNSBL name into a safe name if available. */
+	if (psc_dnsbl_reply == 0
+	    || (safe_dnsbl = dict_get(psc_dnsbl_reply, saved_site)) == 0)
+	    safe_dnsbl = ht->key;
+	head->safe_dnsbl = mystrdup(safe_dnsbl);
+	if (psc_dnsbl_reply && psc_dnsbl_reply->error)
+	    msg_fatal("%s:%s lookup error", psc_dnsbl_reply->type,
+		      psc_dnsbl_reply->name);
+	head->first = 0;
+    }
+
+    /*
+     * Append the new (filter, weight) node to the list for this DNSBL domain
+     * name.
+     */
+    new_site = (PSC_DNSBL_SITE *) mymalloc(sizeof(*new_site));
+    new_site->filter = (pattern_text ? mystrdup(pattern_text) : 0);
+    new_site->byte_codes = (byte_codes ? ip_match_save(byte_codes) : 0);
+    new_site->weight = weight;
+    new_site->next = head->first;
+    head->first = new_site;
+
+    myfree(saved_site);
+    if (byte_codes)
+	vstring_free(byte_codes);
+}
+
+/* psc_dnsbl_match - match DNSBL reply filter */
+
+static int psc_dnsbl_match(const char *filter, ARGV *reply)
+{
+    char    addr_buf[MAI_HOSTADDR_STRSIZE];
+    char  **cpp;
+
+    /*
+     * Run the replies through the pattern-matching engine.
+     */
+    for (cpp = reply->argv; *cpp != 0; cpp++) {
+	if (inet_pton(AF_INET, *cpp, addr_buf) != 1)
+	    msg_warn("address conversion error for %s -- ignoring this reply",
+		     *cpp);
+	if (ip_match_execute(filter, addr_buf))
+	    return (1);
+    }
+    return (0);
+}
+
+/* psc_dnsbl_retrieve - retrieve blocklist score, decrement reference count */
+
+int     psc_dnsbl_retrieve(const char *client_addr, const char **dnsbl_name,
+			           int dnsbl_index, int *dnsbl_ttl)
+{
+    const char *myname = "psc_dnsbl_retrieve";
+    PSC_DNSBL_SCORE *score;
+    int     result_score;
+    int     result_ttl;
+
+    /*
+     * Sanity check.
+     */
+    if ((score = (PSC_DNSBL_SCORE *)
+	 htable_find(dnsbl_score_cache, client_addr)) == 0)
+	msg_panic("%s: no blocklist score for %s", myname, client_addr);
+
+    /*
+     * Disable callbacks.
+     */
+    PSC_CALL_BACK_CANCEL(score, dnsbl_index);
+
+    /*
+     * Reads are destructive.
+     */
+    result_score = score->total;
+    *dnsbl_name = score->dnsbl_name;
+    result_ttl = (result_score > 0) ? score->fail_ttl : score->pass_ttl;
+    /* As with dnsblog(8), a value < 0 means no reply TTL. */
+    if (result_ttl < var_psc_dnsbl_min_ttl)
+	result_ttl = var_psc_dnsbl_min_ttl;
+    if (result_ttl > var_psc_dnsbl_max_ttl)
+	result_ttl = var_psc_dnsbl_max_ttl;
+    *dnsbl_ttl = result_ttl;
+    if (msg_verbose)
+	msg_info("%s: addr=%s score=%d ttl=%d",
+		 myname, client_addr, result_score, result_ttl);
+    score->refcount -= 1;
+    if (score->refcount < 1) {
+	if (msg_verbose > 1)
+	    msg_info("%s: delete blocklist score for %s", myname, client_addr);
+	htable_delete(dnsbl_score_cache, client_addr, myfree);
+    }
+    return (result_score);
+}
+
+/* psc_dnsbl_receive - receive DNSBL reply, update blocklist score */
+
+static void psc_dnsbl_receive(int event, void *context)
+{
+    const char *myname = "psc_dnsbl_receive";
+    VSTREAM *stream = (VSTREAM *) context;
+    PSC_DNSBL_SCORE *score;
+    PSC_DNSBL_HEAD *head;
+    PSC_DNSBL_SITE *site;
+    ARGV   *reply_argv;
+    int     request_id;
+    int     dnsbl_ttl;
+
+    PSC_CLEAR_EVENT_REQUEST(vstream_fileno(stream), psc_dnsbl_receive, context);
+
+    /*
+     * Receive the DNSBL lookup result.
+     * 
+     * This is preliminary code to explore the field. Later, DNSBL lookup will
+     * be handled by an UDP-based DNS client that is built directly into some
+     * Postfix daemon.
+     * 
+     * Don't bother looking up the blocklist score when the client IP address is
+     * not listed at the DNSBL.
+     * 
+     * Don't panic when the blocklist score no longer exists. It may be deleted
+     * when the client triggers a "drop" action after pregreet, when the
+     * client does not pregreet and the DNSBL reply arrives late, or when the
+     * client triggers a "drop" action after hanging up.
+     */
+    if (event == EVENT_READ
+	&& attr_scan(stream,
+		     ATTR_FLAG_STRICT,
+		     RECV_ATTR_STR(MAIL_ATTR_RBL_DOMAIN, reply_dnsbl),
+		     RECV_ATTR_STR(MAIL_ATTR_ACT_CLIENT_ADDR, reply_client),
+		     RECV_ATTR_INT(MAIL_ATTR_LABEL, &request_id),
+		     RECV_ATTR_STR(MAIL_ATTR_RBL_ADDR, reply_addr),
+		     RECV_ATTR_INT(MAIL_ATTR_TTL, &dnsbl_ttl),
+		     ATTR_TYPE_END) == 5
+	&& (score = (PSC_DNSBL_SCORE *)
+	    htable_find(dnsbl_score_cache, STR(reply_client))) != 0
+	&& score->request_id == request_id) {
+
+	/*
+	 * Run this response past all applicable DNSBL filters and update the
+	 * blocklist score for this client IP address.
+	 * 
+	 * Don't panic when the DNSBL domain name is not found. The DNSBLOG
+	 * server may be messed up.
+	 */
+	if (msg_verbose > 1)
+	    msg_info("%s: client=\"%s\" score=%d domain=\"%s\" reply=\"%d %s\"",
+		     myname, STR(reply_client), score->total,
+		     STR(reply_dnsbl), dnsbl_ttl, STR(reply_addr));
+	head = (PSC_DNSBL_HEAD *)
+	    htable_find(dnsbl_site_cache, STR(reply_dnsbl));
+	if (head == 0) {
+	    /* Bogus domain. Do nothing. */
+	} else if (*STR(reply_addr) != 0) {
+	    /* DNS reputation record(s) found. */
+	    reply_argv = 0;
+	    for (site = head->first; site != 0; site = site->next) {
+		if (site->byte_codes == 0
+		    || psc_dnsbl_match(site->byte_codes, reply_argv ? reply_argv :
+			 (reply_argv = argv_split(STR(reply_addr), " ")))) {
+		    if (score->dnsbl_name == 0
+			|| score->dnsbl_weight < site->weight) {
+			score->dnsbl_name = head->safe_dnsbl;
+			score->dnsbl_weight = site->weight;
+		    }
+		    score->total += site->weight;
+		    if (msg_verbose > 1)
+			msg_info("%s: filter=\"%s\" weight=%d score=%d",
+			       myname, site->filter ? site->filter : "null",
+				 site->weight, score->total);
+		}
+		/* As with dnsblog(8), a value < 0 means no reply TTL. */
+		if (site->weight > 0) {
+		    if (score->fail_ttl < 0 || score->fail_ttl > dnsbl_ttl)
+			score->fail_ttl = dnsbl_ttl;
+		} else {
+		    if (score->pass_ttl < 0 || score->pass_ttl > dnsbl_ttl)
+			score->pass_ttl = dnsbl_ttl;
+		}
+	    }
+	    if (reply_argv != 0)
+		argv_free(reply_argv);
+	} else {
+	    /* No DNS reputation record found. */
+	    for (site = head->first; site != 0; site = site->next) {
+		/* As with dnsblog(8), a value < 0 means no reply TTL. */
+		if (site->weight > 0) {
+		    if (score->pass_ttl < 0 || score->pass_ttl > dnsbl_ttl)
+			score->pass_ttl = dnsbl_ttl;
+		} else {
+		    if (score->fail_ttl < 0 || score->fail_ttl > dnsbl_ttl)
+			score->fail_ttl = dnsbl_ttl;
+		}
+	    }
+	}
+
+	/*
+	 * Notify the requestor(s) that the result is ready to be picked up.
+	 * If this call isn't made, clients have to sit out the entire
+	 * pre-handshake delay.
+	 */
+	score->pending_lookups -= 1;
+	if (score->pending_lookups == 0)
+	    PSC_CALL_BACK_NOTIFY(score, PSC_NULL_EVENT);
+    } else if (event == EVENT_TIME) {
+	msg_warn("dnsblog reply timeout %ds for %s",
+		 var_psc_dnsbl_tmout, (char *) vstream_context(stream));
+    }
+    /* Here, score may be a null pointer. */
+    vstream_fclose(stream);
+}
+
+/* psc_dnsbl_request  - send dnsbl query, increment reference count */
+
+int     psc_dnsbl_request(const char *client_addr,
+			          void (*callback) (int, void *),
+			          void *context)
+{
+    const char *myname = "psc_dnsbl_request";
+    int     fd;
+    VSTREAM *stream;
+    HTABLE_INFO **ht;
+    PSC_DNSBL_SCORE *score;
+    HTABLE_INFO *hash_node;
+    static int request_count;
+
+    /*
+     * Some spambots make several connections at nearly the same time,
+     * causing their pregreet delays to overlap. Such connections can share
+     * the efforts of DNSBL lookup.
+     * 
+     * We store a reference-counted DNSBL score under its client IP address. We
+     * increment the reference count with each score request, and decrement
+     * the reference count with each score retrieval.
+     * 
+     * Do not notify the requestor NOW when the DNS replies are already in.
+     * Reason: we must not make a backwards call while we are still in the
+     * middle of executing the corresponding forward call. Instead we create
+     * a zero-delay timer request and call the notification function from
+     * there.
+     * 
+     * psc_dnsbl_request() could instead return a result value to indicate that
+     * the DNSBL score is already available, but that would complicate the
+     * caller with two different notification code paths: one asynchronous
+     * code path via the callback invocation, and one synchronous code path
+     * via the psc_dnsbl_request() result value. That would be a source of
+     * future bugs.
+     */
+    if ((hash_node = htable_locate(dnsbl_score_cache, client_addr)) != 0) {
+	score = (PSC_DNSBL_SCORE *) hash_node->value;
+	score->refcount += 1;
+	PSC_CALL_BACK_EXTEND(hash_node, score);
+	PSC_CALL_BACK_ENTER(score, callback, context);
+	if (msg_verbose > 1)
+	    msg_info("%s: reuse blocklist score for %s refcount=%d pending=%d",
+		     myname, client_addr, score->refcount,
+		     score->pending_lookups);
+	if (score->pending_lookups == 0)
+	    event_request_timer(callback, context, EVENT_NULL_DELAY);
+	return (PSC_CALL_BACK_INDEX_OF_LAST(score));
+    }
+    if (msg_verbose > 1)
+	msg_info("%s: create blocklist score for %s", myname, client_addr);
+    score = (PSC_DNSBL_SCORE *) mymalloc(sizeof(*score));
+    score->request_id = request_count++;
+    score->dnsbl_name = 0;
+    score->dnsbl_weight = 0;
+    /* As with dnsblog(8), a value < 0 means no reply TTL. */
+    score->pass_ttl = -1;
+    score->fail_ttl = -1;
+    score->total = 0;
+    score->refcount = 1;
+    score->pending_lookups = 0;
+    PSC_CALL_BACK_INIT(score);
+    PSC_CALL_BACK_ENTER(score, callback, context);
+    (void) htable_enter(dnsbl_score_cache, client_addr, (void *) score);
+
+    /*
+     * Send a query to all DNSBL servers. Later, DNSBL lookup will be done
+     * with an UDP-based DNS client that is built directly into Postfix code.
+     * We therefore do not optimize the maximum out of this temporary
+     * implementation.
+     */
+    for (ht = dnsbl_site_list; *ht; ht++) {
+	if ((fd = LOCAL_CONNECT(psc_dnsbl_service, NON_BLOCKING, 1)) < 0) {
+	    msg_warn("%s: connect to %s service: %m",
+		     myname, psc_dnsbl_service);
+	    continue;
+	}
+	stream = vstream_fdopen(fd, O_RDWR);
+	vstream_control(stream,
+			CA_VSTREAM_CTL_CONTEXT(ht[0]->key),
+			CA_VSTREAM_CTL_END);
+	attr_print(stream, ATTR_FLAG_NONE,
+		   SEND_ATTR_STR(MAIL_ATTR_RBL_DOMAIN, ht[0]->key),
+		   SEND_ATTR_STR(MAIL_ATTR_ACT_CLIENT_ADDR, client_addr),
+		   SEND_ATTR_INT(MAIL_ATTR_LABEL, score->request_id),
+		   ATTR_TYPE_END);
+	if (vstream_fflush(stream) != 0) {
+	    msg_warn("%s: error sending to %s service: %m",
+		     myname, psc_dnsbl_service);
+	    vstream_fclose(stream);
+	    continue;
+	}
+	PSC_READ_EVENT_REQUEST(vstream_fileno(stream), psc_dnsbl_receive,
+			       (void *) stream, var_psc_dnsbl_tmout);
+	score->pending_lookups += 1;
+    }
+    return (PSC_CALL_BACK_INDEX_OF_LAST(score));
+}
+
+/* psc_dnsbl_init - initialize */
+
+void    psc_dnsbl_init(void)
+{
+    const char *myname = "psc_dnsbl_init";
+    ARGV   *dnsbl_site = argv_split(var_psc_dnsbl_sites, CHARS_COMMA_SP);
+    char  **cpp;
+
+    /*
+     * Sanity check.
+     */
+    if (dnsbl_site_cache != 0)
+	msg_panic("%s: called more than once", myname);
+
+    /*
+     * pre-compute the DNSBLOG socket name.
+     */
+    psc_dnsbl_service = concatenate(MAIL_CLASS_PRIVATE, "/",
+				    var_dnsblog_service, (char *) 0);
+
+    /*
+     * Prepare for quick iteration when sending out queries to all DNSBL
+     * servers, and for quick lookup when a reply arrives from a specific
+     * DNSBL server.
+     */
+    dnsbl_site_cache = htable_create(13);
+    for (cpp = dnsbl_site->argv; *cpp; cpp++)
+	psc_dnsbl_add_site(*cpp);
+    argv_free(dnsbl_site);
+    dnsbl_site_list = htable_list(dnsbl_site_cache);
+
+    /*
+     * The per-client blocklist score.
+     */
+    dnsbl_score_cache = htable_create(13);
+
+    /*
+     * Space for ad-hoc DNSBLOG server request/reply parameters.
+     */
+    reply_client = vstring_alloc(100);
+    reply_dnsbl = vstring_alloc(100);
+    reply_addr = vstring_alloc(100);
+}