+/** START:some missing macros on OpenBSD 3.9 */
+#ifndef NS_CMPRSFLGS
+#define NS_CMPRSFLGS 0xc0
+#endif
+#if !defined(NS_MAXCDNAME) && defined (MAXCDNAME)
+#define NS_MAXCDNAME MAXCDNAME
+#endif
+#if !defined(NS_INT16SZ) && defined(INT16SZ)
+#define NS_INT16SZ INT16SZ
+#define NS_INT32SZ INT32SZ
+#endif
+#ifndef NS_GET16
+# define NS_GET16 GETSHORT
+#endif
+
+/** END:some missing macros on OpenBSD 3.9 */
+
+/*
+ * Given an open client socket, return the host name and IP address at the other end.
+ * (IPv4 and IPv6 compatible)
+ */
+void locate_host(char *tbuf, size_t n, char *abuf, size_t na, int client_socket)
+{
+ struct sockaddr_in6 clientaddr;
+ unsigned int addrlen = sizeof(clientaddr);
+
+ tbuf[0] = 0;
+ abuf[0] = 0;
+
+ getpeername(client_socket, (struct sockaddr *)&clientaddr, &addrlen);
+ getnameinfo((struct sockaddr *)&clientaddr, addrlen, tbuf, n, NULL, 0, 0);
+ getnameinfo((struct sockaddr *)&clientaddr, addrlen, abuf, na, NULL, 0, NI_NUMERICHOST);
+
+ /* Convert IPv6-mapped IPv4 addresses back to traditional dotted quad.
+ *
+ * Other code here, such as the RBL check, will expect IPv4 addresses to be represented
+ * as dotted-quad, even if they come in over a hybrid IPv6/IPv4 socket.
+ */
+ if ( (strlen(abuf) > 7) && (!strncasecmp(abuf, "::ffff:", 7)) ) {
+ if (!strcmp(abuf, tbuf)) strcpy(tbuf, &tbuf[7]);
+ strcpy(abuf, &abuf[7]);
+ }
+}
+
+
+/*
+ * RBL check written by Edward S. Marshall [http://rblcheck.sourceforge.net]
+ */
+#define RESULT_SIZE 4096 /* What is the longest result text we support? */
+int rblcheck_backend(char *domain, char *txtbuf, int txtbufsize) {
+ int a, b, c;
+ char *result = NULL;
+ u_char fixedans[ PACKETSZ ];
+ u_char *answer;
+ int need_to_free_answer = 0;
+ const u_char *cp;
+ u_char *rp;
+ const u_char *cend;
+ const u_char *rend;
+ int len;
+ char *p = NULL;
+ static int res_initted = 0;
+
+ if (!res_initted) { /* only have to do this once */
+ res_init();
+ res_initted = 1;
+ }
+
+ /* Make our DNS query. */
+ answer = fixedans;
+ if (server_shutting_down)
+ {
+ if (txtbuf != NULL) {
+ snprintf(txtbuf, txtbufsize, "System shutting down");
+ }
+ return (1);
+ }
+ len = res_query(domain, C_IN, T_A, answer, PACKETSZ);
+
+ /* Was there a problem? If so, the domain doesn't exist. */
+ if (len == -1) {
+ if (txtbuf != NULL) {
+ strcpy(txtbuf, "");
+ }
+ return(0);
+ }
+
+ if( len > PACKETSZ )
+ {
+ answer = malloc(len);
+ need_to_free_answer = 1;
+ len = res_query(domain, C_IN, T_A, answer, len);
+ if( len == -1 ) {
+ if (txtbuf != NULL) {
+ snprintf(txtbuf, txtbufsize,
+ "Message rejected due to known spammer source IP address");
+ }
+ if (need_to_free_answer) free(answer);
+ return(1);
+ }
+ }
+ if (server_shutting_down)
+ {
+ if (txtbuf != NULL)
+ snprintf(txtbuf, txtbufsize, "System shutting down");
+ if (need_to_free_answer) free(answer);
+ return (1);
+ }
+
+ result = (char *) malloc(RESULT_SIZE);
+ result[ 0 ] = '\0';
+
+
+ /* Make another DNS query for textual data; this shouldn't
+ * be a performance hit, since it'll now be cached at the
+ * nameserver we're using.
+ */
+ len = res_query(domain, C_IN, T_TXT, answer, PACKETSZ);
+ if (server_shutting_down)
+ {
+ if (txtbuf != NULL) {
+ snprintf(txtbuf, txtbufsize, "System shutting down");
+ }
+ if (need_to_free_answer) free(answer);
+ free(result);
+ return (1);
+ }
+
+ /* Just in case there's no TXT record... */
+ if (len ==(-1))
+ {
+ if (txtbuf != NULL) {
+ snprintf(txtbuf, txtbufsize,
+ "Message rejected due to known spammer source IP address");
+ }
+ if (need_to_free_answer) free(answer);
+ free(result);
+ return(1);
+ }
+
+ /* Skip the header and the address we queried. */
+ cp = answer + sizeof( HEADER );
+ while( *cp != '\0' )
+ {
+ a = *cp++;
+ while( a-- )
+ cp++;
+ }
+
+ /* This seems to be a bit of magic data that we need to
+ * skip. I wish there were good online documentation
+ * for programming for libresolv, so I'd know what I'm
+ * skipping here. Anyone reading this, feel free to
+ * enlighten me.
+ */
+ cp += 1 + NS_INT16SZ + NS_INT32SZ;
+
+ /* Skip the type, class and ttl. */
+ cp += (NS_INT16SZ * 2) + NS_INT32SZ;
+
+ /* Get the length and end of the buffer. */
+ NS_GET16(c, cp);
+ cend = cp + c;
+
+ /* Iterate over any multiple answers we might have. In
+ * this context, it's unlikely, but anyway.
+ */
+ rp = (u_char *) result;
+ rend = (u_char *) result + RESULT_SIZE - 1;
+ while (cp < cend && rp < rend)
+ {
+ a = *cp++;
+ if( a != 0 )
+ for (b = a; b > 0 && cp < cend && rp < rend; b--)
+ {
+ if (*cp == '\n' || *cp == '"' || *cp == '\\')
+ {
+ *rp++ = '\\';
+ }
+ *rp++ = *cp++;
+ }
+ }
+ *rp = '\0';
+ if (txtbuf != NULL) {
+ long len;
+ len = snprintf(txtbuf, txtbufsize, "%s", result);
+
+ /* Remove nonprintable characters */
+ for (p = txtbuf; *p != '\0'; p++) {
+ if (!isprint(*p)) {
+ memmove (p,
+ p + 1,
+ len - (p - txtbuf) - 1);
+ }
+ }
+ }
+ if (need_to_free_answer) free(answer);
+ free(result);
+ return(1);
+}
+
+
+/*
+ * Check to see if the client host is on some sort of spam list (RBL)
+ * If spammer, returns nonzero and places reason in 'message_to_spammer'
+ */
+int rbl_check(char *message_to_spammer)