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+/*++
+/* NAME
+/* dnsblog 8
+/* SUMMARY
+/* Postfix DNS white/blacklist logger
+/* SYNOPSIS
+/* \fBdnsblog\fR [generic Postfix daemon options]
+/* DESCRIPTION
+/* The \fBdnsblog\fR(8) server implements an ad-hoc DNS
+/* white/blacklist lookup service. This may eventually be
+/* replaced by an UDP client that is built directly into the
+/* \fBpostscreen\fR(8) server.
+/* PROTOCOL
+/* .ad
+/* .fi
+/* With each connection, the \fBdnsblog\fR(8) server receives
+/* a DNS white/blacklist domain name, an IP address, and an ID.
+/* If the IP address is listed under the DNS white/blacklist, the
+/* \fBdnsblog\fR(8) server logs the match and replies with the
+/* query arguments plus an address list with the resulting IP
+/* addresses, separated by whitespace, and the reply TTL.
+/* Otherwise it replies with the query arguments plus an empty
+/* address list and the reply TTL; the reply TTL is -1 if there
+/* is no reply, or a negative reply that contains no SOA record.
+/* Finally, the \fBdnsblog\fR(8) server closes the connection.
+/* DIAGNOSTICS
+/* Problems and transactions are logged to \fBsyslogd\fR(8)
+/* or \fBpostlogd\fR(8).
+/* CONFIGURATION PARAMETERS
+/* .ad
+/* .fi
+/* Changes to \fBmain.cf\fR are picked up automatically, as
+/* \fBdnsblog\fR(8) processes run for only a limited amount
+/* of time. Use the command "\fBpostfix reload\fR" to speed
+/* up a change.
+/*
+/* The text below provides only a parameter summary. See
+/* \fBpostconf\fR(5) for more details including examples.
+/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
+/* The default location of the Postfix main.cf and master.cf
+/* configuration files.
+/* .IP "\fBdaemon_timeout (18000s)\fR"
+/* How much time a Postfix daemon process may take to handle a
+/* request before it is terminated by a built-in watchdog timer.
+/* .IP "\fBpostscreen_dnsbl_sites (empty)\fR"
+/* Optional list of DNS white/blacklist domains, filters and weight
+/* factors.
+/* .IP "\fBipc_timeout (3600s)\fR"
+/* The time limit for sending or receiving information over an internal
+/* communication channel.
+/* .IP "\fBprocess_id (read-only)\fR"
+/* The process ID of a Postfix command or daemon process.
+/* .IP "\fBprocess_name (read-only)\fR"
+/* The process name of a Postfix command or daemon process.
+/* .IP "\fBqueue_directory (see 'postconf -d' output)\fR"
+/* The location of the Postfix top-level queue directory.
+/* .IP "\fBsyslog_facility (mail)\fR"
+/* The syslog facility of Postfix logging.
+/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
+/* A prefix that is prepended to the process name in syslog
+/* records, so that, for example, "smtpd" becomes "prefix/smtpd".
+/* .PP
+/* Available in Postfix 3.3 and later:
+/* .IP "\fBservice_name (read-only)\fR"
+/* The master.cf service name of a Postfix daemon process.
+/* SEE ALSO
+/* smtpd(8), Postfix SMTP server
+/* postconf(5), configuration parameters
+/* postlogd(8), Postfix logging
+/* syslogd(8), system logging
+/* LICENSE
+/* .ad
+/* .fi
+/* The Secure Mailer license must be distributed with this software.
+/* HISTORY
+/* .ad
+/* .fi
+/* This service was introduced with Postfix version 2.8.
+/* 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 <limits.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <vstream.h>
+#include <vstring.h>
+#include <argv.h>
+#include <myaddrinfo.h>
+#include <valid_hostname.h>
+#include <sock_addr.h>
+
+/* Global library. */
+
+#include <mail_conf.h>
+#include <mail_version.h>
+#include <mail_proto.h>
+#include <mail_params.h>
+
+/* DNS library. */
+
+#include <dns.h>
+
+/* Server skeleton. */
+
+#include <mail_server.h>
+
+/* Application-specific. */
+
+ /*
+ * Tunable parameters.
+ */
+int var_dnsblog_delay;
+
+ /*
+ * Static so we don't allocate and free on every request.
+ */
+static VSTRING *rbl_domain;
+static VSTRING *addr;
+static VSTRING *query;
+static VSTRING *why;
+static VSTRING *result;
+
+ /*
+ * Silly little macros.
+ */
+#define STR(x) vstring_str(x)
+#define LEN(x) VSTRING_LEN(x)
+
+/* static void dnsblog_query - query DNSBL for client address */
+
+static VSTRING *dnsblog_query(VSTRING *result, int *result_ttl,
+ const char *dnsbl_domain,
+ const char *addr)
+{
+ const char *myname = "dnsblog_query";
+ ARGV *octets;
+ int i;
+ struct addrinfo *res;
+ unsigned char *ipv6_addr;
+ int dns_status;
+ DNS_RR *addr_list;
+ DNS_RR *rr;
+ MAI_HOSTADDR_STR hostaddr;
+
+ if (msg_verbose)
+ msg_info("%s: addr %s dnsbl_domain %s",
+ myname, addr, dnsbl_domain);
+
+ VSTRING_RESET(query);
+
+ /*
+ * Reverse the client IPV6 address, represented as 32 hexadecimal
+ * nibbles. We use the binary address to avoid tricky code. Asking for an
+ * AAAA record makes no sense here. Just like with IPv4 we use the lookup
+ * result as a bit mask, not as an IP address.
+ */
+#ifdef HAS_IPV6
+ if (valid_ipv6_hostaddr(addr, DONT_GRIPE)) {
+ if (hostaddr_to_sockaddr(addr, (char *) 0, 0, &res) != 0
+ || res->ai_family != PF_INET6)
+ msg_fatal("%s: unable to convert address %s", myname, addr);
+ ipv6_addr = (unsigned char *) &SOCK_ADDR_IN6_ADDR(res->ai_addr);
+ for (i = sizeof(SOCK_ADDR_IN6_ADDR(res->ai_addr)) - 1; i >= 0; i--)
+ vstring_sprintf_append(query, "%x.%x.",
+ ipv6_addr[i] & 0xf, ipv6_addr[i] >> 4);
+ freeaddrinfo(res);
+ } else
+#endif
+
+ /*
+ * Reverse the client IPV4 address, represented as four decimal octet
+ * values. We use the textual address for convenience.
+ */
+ {
+ octets = argv_split(addr, ".");
+ for (i = octets->argc - 1; i >= 0; i--) {
+ vstring_strcat(query, octets->argv[i]);
+ vstring_strcat(query, ".");
+ }
+ argv_free(octets);
+ }
+
+ /*
+ * Tack on the RBL domain name and query the DNS for an A record.
+ */
+ vstring_strcat(query, dnsbl_domain);
+ dns_status = dns_lookup_x(STR(query), T_A, 0, &addr_list, (VSTRING *) 0,
+ why, (int *) 0, DNS_REQ_FLAG_NCACHE_TTL);
+
+ /*
+ * We return the lowest TTL in the response from the A record(s) if
+ * found, or from the SOA record(s) if available. If the reply specifies
+ * no TTL, or if the query fails, we return a TTL of -1.
+ */
+ VSTRING_RESET(result);
+ *result_ttl = -1;
+ if (dns_status == DNS_OK) {
+ for (rr = addr_list; rr != 0; rr = rr->next) {
+ if (dns_rr_to_pa(rr, &hostaddr) == 0) {
+ msg_warn("%s: skipping reply record type %s for query %s: %m",
+ myname, dns_strtype(rr->type), STR(query));
+ } else {
+ msg_info("addr %s listed by domain %s as %s",
+ addr, dnsbl_domain, hostaddr.buf);
+ if (LEN(result) > 0)
+ vstring_strcat(result, " ");
+ vstring_strcat(result, hostaddr.buf);
+ /* Grab the positive reply TTL. */
+ if (*result_ttl < 0 || *result_ttl > rr->ttl)
+ *result_ttl = rr->ttl;
+ }
+ }
+ dns_rr_free(addr_list);
+ } else if (dns_status == DNS_NOTFOUND) {
+ if (msg_verbose)
+ msg_info("%s: addr %s not listed by domain %s",
+ myname, addr, dnsbl_domain);
+ /* Grab the negative reply TTL. */
+ for (rr = addr_list; rr != 0; rr = rr->next) {
+ if (rr->type == T_SOA && (*result_ttl < 0 || *result_ttl > rr->ttl))
+ *result_ttl = rr->ttl;
+ }
+ dns_rr_free(addr_list);
+ } else {
+ msg_warn("%s: lookup error for DNS query %s: %s",
+ myname, STR(query), STR(why));
+ }
+ VSTRING_TERMINATE(result);
+ return (result);
+}
+
+/* dnsblog_service - perform service for client */
+
+static void dnsblog_service(VSTREAM *client_stream, char *unused_service,
+ char **argv)
+{
+ int request_id;
+ int result_ttl;
+
+ /*
+ * Sanity check. This service takes no command-line arguments.
+ */
+ if (argv[0])
+ msg_fatal("unexpected command-line argument: %s", argv[0]);
+
+ /*
+ * This routine runs whenever a client connects to the socket dedicated
+ * to the dnsblog service. All connection-management stuff is handled by
+ * the common code in single_server.c.
+ */
+ if (attr_scan(client_stream,
+ ATTR_FLAG_MORE | ATTR_FLAG_STRICT,
+ RECV_ATTR_STR(MAIL_ATTR_RBL_DOMAIN, rbl_domain),
+ RECV_ATTR_STR(MAIL_ATTR_ACT_CLIENT_ADDR, addr),
+ RECV_ATTR_INT(MAIL_ATTR_LABEL, &request_id),
+ ATTR_TYPE_END) == 3) {
+ (void) dnsblog_query(result, &result_ttl, STR(rbl_domain), STR(addr));
+ if (var_dnsblog_delay > 0)
+ sleep(var_dnsblog_delay);
+ attr_print(client_stream, ATTR_FLAG_NONE,
+ SEND_ATTR_STR(MAIL_ATTR_RBL_DOMAIN, STR(rbl_domain)),
+ SEND_ATTR_STR(MAIL_ATTR_ACT_CLIENT_ADDR, STR(addr)),
+ SEND_ATTR_INT(MAIL_ATTR_LABEL, request_id),
+ SEND_ATTR_STR(MAIL_ATTR_RBL_ADDR, STR(result)),
+ SEND_ATTR_INT(MAIL_ATTR_TTL, result_ttl),
+ ATTR_TYPE_END);
+ vstream_fflush(client_stream);
+ }
+}
+
+/* post_jail_init - post-jail initialization */
+
+static void post_jail_init(char *unused_name, char **unused_argv)
+{
+ rbl_domain = vstring_alloc(100);
+ addr = vstring_alloc(100);
+ query = vstring_alloc(100);
+ why = vstring_alloc(100);
+ result = vstring_alloc(100);
+ var_use_limit = 0;
+}
+
+MAIL_VERSION_STAMP_DECLARE;
+
+/* main - pass control to the multi-threaded skeleton */
+
+int main(int argc, char **argv)
+{
+ static const CONFIG_TIME_TABLE time_table[] = {
+ VAR_DNSBLOG_DELAY, DEF_DNSBLOG_DELAY, &var_dnsblog_delay, 0, 0,
+ 0,
+ };
+
+ /*
+ * Fingerprint executables and core dumps.
+ */
+ MAIL_VERSION_STAMP_ALLOCATE;
+
+ single_server_main(argc, argv, dnsblog_service,
+ CA_MAIL_SERVER_TIME_TABLE(time_table),
+ CA_MAIL_SERVER_POST_INIT(post_jail_init),
+ CA_MAIL_SERVER_UNLIMITED,
+ CA_MAIL_SERVER_RETIRE_ME,
+ 0);
+}