+ /* 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) {
+ snprintf(txtbuf, txtbufsize, "%s", result);
+ }
+ /* Remove nonprintable characters */
+ for (p=txtbuf; *p; ++p) {
+ if (!isprint(*p)) strcpy(p, p+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)
+{
+ char tbuf[256] = "";
+ int suffix_pos = 0;
+ int rbl;
+ int num_rbl;
+ char rbl_domains[SIZ];
+ char txt_answer[1024];
+
+ strcpy(message_to_spammer, "ok");
+
+ if ((strchr(CC->cs_addr, '.')) && (!strchr(CC->cs_addr, ':'))) {
+ int a1, a2, a3, a4;
+
+ sscanf(CC->cs_addr, "%d.%d.%d.%d", &a1, &a2, &a3, &a4);
+ snprintf(tbuf, sizeof tbuf, "%d.%d.%d.%d.", a4, a3, a2, a1);
+ suffix_pos = strlen(tbuf);
+ }
+ else if ((!strchr(CC->cs_addr, '.')) && (strchr(CC->cs_addr, ':'))) {
+ int num_colons = 0;
+ int i = 0;
+ char workbuf[sizeof tbuf];
+ char *ptr;
+
+ /* tedious code to expand and reverse an IPv6 address */
+ safestrncpy(tbuf, CC->cs_addr, sizeof tbuf);
+ num_colons = haschar(tbuf, ':');
+ if ((num_colons < 2) || (num_colons > 7)) return(0); /* badly formed address */
+
+ /* expand the "::" shorthand */
+ while (num_colons < 7) {
+ ptr = strstr(tbuf, "::");
+ if (!ptr) return(0); /* badly formed address */
+ ++ptr;
+ strcpy(workbuf, ptr);
+ strcpy(ptr, ":");
+ strcat(ptr, workbuf);
+ ++num_colons;
+ }
+
+ /* expand to 32 hex characters with no colons */
+ strcpy(workbuf, tbuf);
+ strcpy(tbuf, "00000000000000000000000000000000");
+ for (i=0; i<8; ++i) {
+ char tokbuf[5];
+ extract_token(tokbuf, workbuf, i, ':', sizeof tokbuf);
+
+ memcpy(&tbuf[ (i*4) + (4-strlen(tokbuf)) ], tokbuf, strlen(tokbuf) );
+ }
+ if (strlen(tbuf) != 32) return(0);
+
+ /* now reverse it and add dots */
+ strcpy(workbuf, tbuf);
+ for (i=0; i<32; ++i) {
+ tbuf[i*2] = workbuf[31-i];
+ tbuf[(i*2)+1] = '.';
+ }
+ tbuf[64] = 0;
+ suffix_pos = 64;
+ }
+ else {
+ return(0); /* unknown address format */
+ }
+
+ /* See if we have any RBL domains configured */
+ num_rbl = get_hosts(rbl_domains, "rbl");
+ if (num_rbl < 1) return(0);
+
+ /* Try all configured RBL's */
+ for (rbl=0; rbl<num_rbl; ++rbl) {
+ extract_token(&tbuf[suffix_pos], rbl_domains, rbl, '|', (sizeof tbuf - suffix_pos));
+
+ if (rblcheck_backend(tbuf, txt_answer, sizeof txt_answer)) {
+ strcpy(message_to_spammer, txt_answer);
+ syslog(LOG_INFO, "RBL: %s\n", txt_answer);
+ return(1);
+ }
+ }
+
+ return(0);
+}
+
+
+/*
+ * Convert a host name to a dotted quad address.
+ * Returns zero on success or nonzero on failure.
+ *
+ * FIXME this is obviously not IPv6 compatible.
+ */
+int hostname_to_dotted_quad(char *addr, char *host) {
+ struct hostent *ch;
+ const char *i;
+ int a1, a2, a3, a4;
+
+ ch = gethostbyname(host);
+ if (ch == NULL) {
+ strcpy(addr, "0.0.0.0");
+ return(1);
+ }
+
+ i = (const char *) ch->h_addr_list[0];
+ a1 = ((*i++) & 0xff);
+ a2 = ((*i++) & 0xff);
+ a3 = ((*i++) & 0xff);
+ a4 = ((*i++) & 0xff);
+ sprintf(addr, "%d.%d.%d.%d", a1, a2, a3, a4);
+ return(0);