/*
- * locate the originating host
- * $Id$
+ * Functions which handle hostname/address lookups and resolution
+ *
+ * Copyright (c) 1987-2019 by the citadel.org team
+ *
+ * This program is open source software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
*/
#include "sysdep.h"
-#include <stdlib.h>
-#include <unistd.h>
+#include <string.h>
#include <stdio.h>
-#include <signal.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <limits.h>
+#include <syslog.h>
+#include <ctype.h>
#include <netdb.h>
-#include <string.h>
-#ifdef HAVE_PTHREAD_H
-#include <pthread.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <libcitadel.h>
+
+#include "context.h"
+#ifdef HAVE_RESOLV_H
+#include <arpa/nameser.h>
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+#include <arpa/nameser_compat.h>
+#endif
+#include <resolv.h>
#endif
-#include "citadel.h"
-#include "server.h"
+
+#include "domain.h"
#include "locate_host.h"
-#include "config.h"
-void locate_host(char *tbuf, const struct in_addr *addr)
+/* 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 hostent *ch;
- char *i;
- int a1, a2, a3, a4;
+ 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]);
+ }
+}
-#ifdef HAVE_NONREENTRANT_NETDB
- begin_critical_section(S_NETDB);
-#endif
- if ((ch = gethostbyaddr((char *) addr, sizeof(*addr), AF_INET)) ==
- NULL) {
- bad_dns:
- i = (char *) addr;
- a1 = ((*i++) & 0xff);
- a2 = ((*i++) & 0xff);
- a3 = ((*i++) & 0xff);
- a4 = ((*i++) & 0xff);
- sprintf(tbuf, "%d.%d.%d.%d", a1, a2, a3, a4);
- goto end; /* because we might need to end the critical
- section */
- }
- /* check if the forward DNS agrees; if not, they're spoofing */
- i = strdoop(ch->h_name);
- ch = gethostbyname(i);
- phree(i);
- if (ch == NULL)
- goto bad_dns;
-
- /* check address for consistency */
- for (; *ch->h_addr_list; ch->h_addr_list++)
- if (!memcmp(*ch->h_addr_list, addr,
- sizeof *addr)) {
- safestrncpy(tbuf, ch->h_name, 24);
- goto end;
+/*
+ * 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");
}
- goto bad_dns; /* they were spoofing. report a numeric IP
- address. */
+ return (1);
+ }
+ len = res_query(domain, C_IN, T_A, answer, PACKETSZ);
- end:
+ /* Was there a problem? If so, the domain doesn't exist. */
+ if (len == -1) {
+ if (txtbuf != NULL) {
+ strcpy(txtbuf, "");
+ }
+ return(0);
+ }
-#ifdef HAVE_NONREENTRANT_NETDB
- end_critical_section(S_NETDB);
-#endif
+ 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 *cs_addr, char *message_to_spammer)
+{
+ char tbuf[256] = "";
+ int suffix_pos = 0;
+ int rbl;
+ int rc;
+ int num_rbl;
+ char rbl_domains[SIZ];
+ char txt_answer[1024];
+ struct timeval tx_start;
+ struct timeval tx_finish;
+
+ rc = 0;
+ strcpy(message_to_spammer, "ok");
+ gettimeofday(&tx_start, NULL); /* start a stopwatch for performance timing */
+
+ if ((strchr(cs_addr, '.')) && (!strchr(cs_addr, ':'))) {
+ int a1, a2, a3, a4;
+
+ sscanf(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(cs_addr, '.')) && (strchr(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, cs_addr, sizeof tbuf);
+ num_colons = haschar(tbuf, ':');
+ if ((num_colons < 2) || (num_colons > 7))
+ goto finish_rbl; /* badly formed address */
+
+ /* expand the "::" shorthand */
+ while (num_colons < 7) {
+ ptr = strstr(tbuf, "::");
+ if (!ptr)
+ goto finish_rbl; /* 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) {
+ goto finish_rbl;
+ }
+
+ /* 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 {
+ goto finish_rbl; /* unknown address format */
+ }
+
+ /* See if we have any RBL domains configured */
+ num_rbl = get_hosts(rbl_domains, "rbl");
+ if (num_rbl < 1)
+ {
+ goto finish_rbl;
+ }
+
+ /* 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 %s", cs_addr, txt_answer);
+ rc = 1;
+ }
+ }
+finish_rbl:
+ /* How long did this transaction take? */
+ gettimeofday(&tx_finish, NULL);
+
+ syslog(LOG_WARNING, "rbl: %s [%ld.%06ld] %s",
+ cs_addr,
+ ((tx_finish.tv_sec*1000000 + tx_finish.tv_usec) - (tx_start.tv_sec*1000000 + tx_start.tv_usec)) / 1000000,
+ ((tx_finish.tv_sec*1000000 + tx_finish.tv_usec) - (tx_start.tv_sec*1000000 + tx_start.tv_usec)) % 1000000,
+ (rc)?"found":"none found"
+ );
+
+ return rc;
+}
+
+
+/*
+ * 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);
+ }
- tbuf[24] = 0;
+ 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);
}
projects / citadel.git / blobdiff