2 * Functions which handle hostname/address lookups and resolution
4 * Copyright (c) 1987-2019 by the citadel.org team
6 * This program is open source software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License, version 3.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
21 #include <netinet/in.h>
22 #include <arpa/inet.h>
23 #include <libcitadel.h>
27 #include <arpa/nameser.h>
28 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
29 #include <arpa/nameser_compat.h>
35 #include "locate_host.h"
37 /* START: some missing macros on OpenBSD 3.9 */
39 #define NS_CMPRSFLGS 0xc0
41 #if !defined(NS_MAXCDNAME) && defined (MAXCDNAME)
42 #define NS_MAXCDNAME MAXCDNAME
44 #if !defined(NS_INT16SZ) && defined(INT16SZ)
45 #define NS_INT16SZ INT16SZ
46 #define NS_INT32SZ INT32SZ
49 # define NS_GET16 GETSHORT
51 /* END: some missing macros on OpenBSD 3.9 */
55 * Given an open client socket, return the host name and IP address at the other end.
56 * (IPv4 and IPv6 compatible)
58 void locate_host(char *tbuf, size_t n, char *abuf, size_t na, int client_socket)
60 struct sockaddr_in6 clientaddr;
61 unsigned int addrlen = sizeof(clientaddr);
66 getpeername(client_socket, (struct sockaddr *)&clientaddr, &addrlen);
67 getnameinfo((struct sockaddr *)&clientaddr, addrlen, tbuf, n, NULL, 0, 0);
68 getnameinfo((struct sockaddr *)&clientaddr, addrlen, abuf, na, NULL, 0, NI_NUMERICHOST);
70 /* Convert IPv6-mapped IPv4 addresses back to traditional dotted quad.
72 * Other code here, such as the RBL check, will expect IPv4 addresses to be represented
73 * as dotted-quad, even if they come in over a hybrid IPv6/IPv4 socket.
75 if ( (strlen(abuf) > 7) && (!strncasecmp(abuf, "::ffff:", 7)) ) {
76 if (!strcmp(abuf, tbuf)) strcpy(tbuf, &tbuf[7]);
77 strcpy(abuf, &abuf[7]);
83 * RBL check written by Edward S. Marshall [http://rblcheck.sourceforge.net]
85 #define RESULT_SIZE 4096 /* What is the longest result text we support? */
86 int rblcheck_backend(char *domain, char *txtbuf, int txtbufsize) {
89 u_char fixedans[ PACKETSZ ];
91 int need_to_free_answer = 0;
98 static int res_initted = 0;
100 if (!res_initted) { /* only have to do this once */
105 /* Make our DNS query. */
107 if (server_shutting_down) {
108 if (txtbuf != NULL) {
109 snprintf(txtbuf, txtbufsize, "System shutting down");
113 len = res_query(domain, C_IN, T_A, answer, PACKETSZ);
115 /* Was there a problem? If so, the domain doesn't exist. */
117 if (txtbuf != NULL) {
123 if (len > PACKETSZ) {
124 answer = malloc(len);
125 need_to_free_answer = 1;
126 len = res_query(domain, C_IN, T_A, answer, len);
128 if (txtbuf != NULL) {
129 snprintf(txtbuf, txtbufsize, "Message rejected due to known spammer source IP address");
131 if (need_to_free_answer) free(answer);
135 if (server_shutting_down) {
136 if (txtbuf != NULL) {
137 snprintf(txtbuf, txtbufsize, "System shutting down");
139 if (need_to_free_answer) free(answer);
143 result = (char *) malloc(RESULT_SIZE);
146 /* Make another DNS query for textual data; this shouldn't
147 * be a performance hit, since it'll now be cached at the
148 * nameserver we're using.
150 len = res_query(domain, C_IN, T_TXT, answer, PACKETSZ);
151 if (server_shutting_down) {
152 if (txtbuf != NULL) {
153 snprintf(txtbuf, txtbufsize, "System shutting down");
155 if (need_to_free_answer) free(answer);
160 /* Just in case there's no TXT record... */
162 if (txtbuf != NULL) {
163 snprintf(txtbuf, txtbufsize, "Message rejected due to known spammer source IP address");
165 if (need_to_free_answer) free(answer);
170 /* Skip the header and the address we queried. */
171 cp = answer + sizeof( HEADER );
172 while( *cp != '\0' ) {
178 /* This seems to be a bit of magic data that we need to
179 * skip. I wish there were good online documentation
180 * for programming for libresolv, so I'd know what I'm
181 * skipping here. Anyone reading this, feel free to
184 cp += 1 + NS_INT16SZ + NS_INT32SZ;
186 /* Skip the type, class and ttl. */
187 cp += (NS_INT16SZ * 2) + NS_INT32SZ;
189 /* Get the length and end of the buffer. */
193 /* Iterate over any multiple answers we might have. In
194 * this context, it's unlikely, but anyway.
196 rp = (u_char *) result;
197 rend = (u_char *) result + RESULT_SIZE - 1;
198 while (cp < cend && rp < rend) {
201 for (b = a; b > 0 && cp < cend && rp < rend; b--) {
202 if (*cp == '\n' || *cp == '"' || *cp == '\\') {
210 if (txtbuf != NULL) {
212 len = snprintf(txtbuf, txtbufsize, "%s", result);
214 /* Remove nonprintable characters */
215 for (p = txtbuf; *p != '\0'; p++) {
219 len - (p - txtbuf) - 1);
223 if (need_to_free_answer) free(answer);
230 * Check to see if the client host is on some sort of spam list (RBL)
231 * If spammer, returns nonzero and places reason in 'message_to_spammer'
233 int rbl_check(char *cs_addr, char *message_to_spammer)
240 char rbl_domains[SIZ];
241 char txt_answer[1024];
242 struct timeval tx_start;
243 struct timeval tx_finish;
246 strcpy(message_to_spammer, "ok");
247 gettimeofday(&tx_start, NULL); /* start a stopwatch for performance timing */
249 if ((strchr(cs_addr, '.')) && (!strchr(cs_addr, ':'))) {
252 sscanf(cs_addr, "%d.%d.%d.%d", &a1, &a2, &a3, &a4);
253 snprintf(tbuf, sizeof tbuf, "%d.%d.%d.%d.", a4, a3, a2, a1);
254 suffix_pos = strlen(tbuf);
256 else if ((!strchr(cs_addr, '.')) && (strchr(cs_addr, ':'))) {
259 char workbuf[sizeof tbuf];
262 /* tedious code to expand and reverse an IPv6 address */
263 safestrncpy(tbuf, cs_addr, sizeof tbuf);
264 num_colons = haschar(tbuf, ':');
265 if ((num_colons < 2) || (num_colons > 7))
266 goto finish_rbl; /* badly formed address */
268 /* expand the "::" shorthand */
269 while (num_colons < 7) {
270 ptr = strstr(tbuf, "::");
272 goto finish_rbl; /* badly formed address */
275 strcpy(workbuf, ptr);
277 strcat(ptr, workbuf);
281 /* expand to 32 hex characters with no colons */
282 strcpy(workbuf, tbuf);
283 strcpy(tbuf, "00000000000000000000000000000000");
284 for (i=0; i<8; ++i) {
286 extract_token(tokbuf, workbuf, i, ':', sizeof tokbuf);
287 memcpy(&tbuf[ (i*4) + (4-strlen(tokbuf)) ], tokbuf, strlen(tokbuf) );
289 if (strlen(tbuf) != 32) {
293 /* now reverse it and add dots */
294 strcpy(workbuf, tbuf);
295 for (i=0; i<32; ++i) {
296 tbuf[i*2] = workbuf[31-i];
303 goto finish_rbl; /* unknown address format */
306 /* See if we have any RBL domains configured */
307 num_rbl = get_hosts(rbl_domains, "rbl");
313 /* Try all configured RBL's */
314 for (rbl=0; rbl<num_rbl; ++rbl) {
315 extract_token(&tbuf[suffix_pos], rbl_domains, rbl, '|', (sizeof tbuf - suffix_pos));
317 if (rblcheck_backend(tbuf, txt_answer, sizeof txt_answer)) {
318 strcpy(message_to_spammer, txt_answer);
319 syslog(LOG_INFO, "RBL: %s %s", cs_addr, txt_answer);
324 /* How long did this transaction take? */
325 gettimeofday(&tx_finish, NULL);
327 syslog(LOG_WARNING, "rbl: %s [%ld.%06ld] %s",
329 ((tx_finish.tv_sec*1000000 + tx_finish.tv_usec) - (tx_start.tv_sec*1000000 + tx_start.tv_usec)) / 1000000,
330 ((tx_finish.tv_sec*1000000 + tx_finish.tv_usec) - (tx_start.tv_sec*1000000 + tx_start.tv_usec)) % 1000000,
331 (rc)?"found":"none found"
339 * Convert a host name to a dotted quad address.
340 * Returns zero on success or nonzero on failure.
342 * FIXME this is obviously not IPv6 compatible.
344 int hostname_to_dotted_quad(char *addr, char *host) {
349 ch = gethostbyname(host);
351 strcpy(addr, "0.0.0.0");
355 i = (const char *) ch->h_addr_list[0];
356 a1 = ((*i++) & 0xff);
357 a2 = ((*i++) & 0xff);
358 a3 = ((*i++) & 0xff);
359 a4 = ((*i++) & 0xff);
360 sprintf(addr, "%d.%d.%d.%d", a1, a2, a3, a4);