2 * Functions which handle hostname/address lookups and resolution
4 * Copyright (c) 1987-2011 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>
24 #include <libcitadel.h>
29 #include <arpa/nameser.h>
30 #ifdef HAVE_ARPA_NAMESER_COMPAT_H
31 #include <arpa/nameser_compat.h>
37 #include "locate_host.h"
39 /** START:some missing macros on OpenBSD 3.9 */
41 #define NS_CMPRSFLGS 0xc0
43 #if !defined(NS_MAXCDNAME) && defined (MAXCDNAME)
44 #define NS_MAXCDNAME MAXCDNAME
46 #if !defined(NS_INT16SZ) && defined(INT16SZ)
47 #define NS_INT16SZ INT16SZ
48 #define NS_INT32SZ INT32SZ
51 # define NS_GET16 GETSHORT
54 /** END:some missing macros on OpenBSD 3.9 */
57 * Given an open client socket, return the host name and IP address at the other end.
58 * (IPv4 and IPv6 compatible)
60 void locate_host(char *tbuf, size_t n, char *abuf, size_t na, int client_socket)
62 struct sockaddr_in6 clientaddr;
63 unsigned int addrlen = sizeof(clientaddr);
68 getpeername(client_socket, (struct sockaddr *)&clientaddr, &addrlen);
69 getnameinfo((struct sockaddr *)&clientaddr, addrlen, tbuf, n, NULL, 0, 0);
70 getnameinfo((struct sockaddr *)&clientaddr, addrlen, abuf, na, NULL, 0, NI_NUMERICHOST);
72 /* Convert IPv6-mapped IPv4 addresses back to traditional dotted quad.
74 * Other code here, such as the RBL check, will expect IPv4 addresses to be represented
75 * as dotted-quad, even if they come in over a hybrid IPv6/IPv4 socket.
77 if ( (strlen(abuf) > 7) && (!strncasecmp(abuf, "::ffff:", 7)) ) {
78 if (!strcmp(abuf, tbuf)) strcpy(tbuf, &tbuf[7]);
79 strcpy(abuf, &abuf[7]);
85 * RBL check written by Edward S. Marshall [http://rblcheck.sourceforge.net]
87 #define RESULT_SIZE 4096 /* What is the longest result text we support? */
88 int rblcheck_backend(char *domain, char *txtbuf, int txtbufsize) {
91 u_char fixedans[ PACKETSZ ];
93 int need_to_free_answer = 0;
100 static int res_initted = 0;
102 if (!res_initted) { /* only have to do this once */
107 /* Make our DNS query. */
109 if (server_shutting_down)
111 if (txtbuf != NULL) {
112 snprintf(txtbuf, txtbufsize, "System shutting down");
116 len = res_query(domain, C_IN, T_A, answer, PACKETSZ);
118 /* Was there a problem? If so, the domain doesn't exist. */
120 if (txtbuf != NULL) {
128 answer = malloc(len);
129 need_to_free_answer = 1;
130 len = res_query(domain, C_IN, T_A, answer, len);
132 if (txtbuf != NULL) {
133 snprintf(txtbuf, txtbufsize,
134 "Message rejected due to known spammer source IP address");
136 if (need_to_free_answer) free(answer);
140 if (server_shutting_down)
143 snprintf(txtbuf, txtbufsize, "System shutting down");
144 if (need_to_free_answer) free(answer);
148 result = (char *) malloc(RESULT_SIZE);
152 /* Make another DNS query for textual data; this shouldn't
153 * be a performance hit, since it'll now be cached at the
154 * nameserver we're using.
156 len = res_query(domain, C_IN, T_TXT, answer, PACKETSZ);
157 if (server_shutting_down)
159 if (txtbuf != NULL) {
160 snprintf(txtbuf, txtbufsize, "System shutting down");
162 if (need_to_free_answer) free(answer);
167 /* Just in case there's no TXT record... */
170 if (txtbuf != NULL) {
171 snprintf(txtbuf, txtbufsize,
172 "Message rejected due to known spammer source IP address");
174 if (need_to_free_answer) free(answer);
179 /* Skip the header and the address we queried. */
180 cp = answer + sizeof( HEADER );
188 /* This seems to be a bit of magic data that we need to
189 * skip. I wish there were good online documentation
190 * for programming for libresolv, so I'd know what I'm
191 * skipping here. Anyone reading this, feel free to
194 cp += 1 + NS_INT16SZ + NS_INT32SZ;
196 /* Skip the type, class and ttl. */
197 cp += (NS_INT16SZ * 2) + NS_INT32SZ;
199 /* Get the length and end of the buffer. */
203 /* Iterate over any multiple answers we might have. In
204 * this context, it's unlikely, but anyway.
206 rp = (u_char *) result;
207 rend = (u_char *) result + RESULT_SIZE - 1;
208 while (cp < cend && rp < rend)
212 for (b = a; b > 0 && cp < cend && rp < rend; b--)
214 if (*cp == '\n' || *cp == '"' || *cp == '\\')
222 if (txtbuf != NULL) {
224 len = snprintf(txtbuf, txtbufsize, "%s", result);
226 /* Remove nonprintable characters */
227 for (p = txtbuf; *p != '\0'; p++) {
231 len - (p - txtbuf) - 1);
235 if (need_to_free_answer) free(answer);
242 * Check to see if the client host is on some sort of spam list (RBL)
243 * If spammer, returns nonzero and places reason in 'message_to_spammer'
245 int rbl_check(char *message_to_spammer)
252 char rbl_domains[SIZ];
253 char txt_answer[1024];
254 struct timeval tx_start;
255 struct timeval tx_finish;
258 strcpy(message_to_spammer, "ok");
259 gettimeofday(&tx_start, NULL); /* start a stopwatch for performance timing */
261 if ((strchr(CC->cs_addr, '.')) && (!strchr(CC->cs_addr, ':'))) {
264 sscanf(CC->cs_addr, "%d.%d.%d.%d", &a1, &a2, &a3, &a4);
265 snprintf(tbuf, sizeof tbuf, "%d.%d.%d.%d.", a4, a3, a2, a1);
266 suffix_pos = strlen(tbuf);
268 else if ((!strchr(CC->cs_addr, '.')) && (strchr(CC->cs_addr, ':'))) {
271 char workbuf[sizeof tbuf];
274 /* tedious code to expand and reverse an IPv6 address */
275 safestrncpy(tbuf, CC->cs_addr, sizeof tbuf);
276 num_colons = haschar(tbuf, ':');
277 if ((num_colons < 2) || (num_colons > 7))
278 goto finish_rbl; /* badly formed address */
280 /* expand the "::" shorthand */
281 while (num_colons < 7) {
282 ptr = strstr(tbuf, "::");
284 goto finish_rbl; /* badly formed address */
287 strcpy(workbuf, ptr);
289 strcat(ptr, workbuf);
293 /* expand to 32 hex characters with no colons */
294 strcpy(workbuf, tbuf);
295 strcpy(tbuf, "00000000000000000000000000000000");
296 for (i=0; i<8; ++i) {
298 extract_token(tokbuf, workbuf, i, ':', sizeof tokbuf);
300 memcpy(&tbuf[ (i*4) + (4-strlen(tokbuf)) ], tokbuf, strlen(tokbuf) );
302 if (strlen(tbuf) != 32)
305 /* now reverse it and add dots */
306 strcpy(workbuf, tbuf);
307 for (i=0; i<32; ++i) {
308 tbuf[i*2] = workbuf[31-i];
315 goto finish_rbl; /* unknown address format */
318 /* See if we have any RBL domains configured */
319 num_rbl = get_hosts(rbl_domains, "rbl");
325 /* Try all configured RBL's */
326 for (rbl=0; rbl<num_rbl; ++rbl) {
327 extract_token(&tbuf[suffix_pos], rbl_domains, rbl, '|', (sizeof tbuf - suffix_pos));
329 if (rblcheck_backend(tbuf, txt_answer, sizeof txt_answer)) {
330 strcpy(message_to_spammer, txt_answer);
331 syslog(LOG_INFO, "RBL: %s\n", txt_answer);
336 /* How long did this transaction take? */
337 gettimeofday(&tx_finish, NULL);
339 syslog(LOG_WARNING, "RBL [%ld.%06ld] %s",
340 ((tx_finish.tv_sec*1000000 + tx_finish.tv_usec) - (tx_start.tv_sec*1000000 + tx_start.tv_usec)) / 1000000,
341 ((tx_finish.tv_sec*1000000 + tx_finish.tv_usec) - (tx_start.tv_sec*1000000 + tx_start.tv_usec)) % 1000000,
342 (rc)?"Found":"none Found");
349 * Convert a host name to a dotted quad address.
350 * Returns zero on success or nonzero on failure.
352 * FIXME this is obviously not IPv6 compatible.
354 int hostname_to_dotted_quad(char *addr, char *host) {
359 ch = gethostbyname(host);
361 strcpy(addr, "0.0.0.0");
365 i = (const char *) ch->h_addr_list[0];
366 a1 = ((*i++) & 0xff);
367 a2 = ((*i++) & 0xff);
368 a3 = ((*i++) & 0xff);
369 a4 = ((*i++) & 0xff);
370 sprintf(addr, "%d.%d.%d.%d", a1, a2, a3, a4);