X-Git-Url: https://code.citadel.org/?a=blobdiff_plain;f=citadel%2Flocate_host.c;h=d964bc72e0f27972e1dca54708076ccaba031baf;hb=aa7365c86de8e26e796d3aa3fd605c85d8c26220;hp=1ca321e330e1d4516b1dbae0323ae4f84d9d50af;hpb=96b0341b80d80ed72ba032e340452653816d8c64;p=citadel.git

diff --git a/citadel/locate_host.c b/citadel/locate_host.c
index 1ca321e33..d964bc72e 100644
--- a/citadel/locate_host.c
+++ b/citadel/locate_host.c
@@ -1,80 +1,361 @@
 /*
- * $Id$
+ * Functions which handle hostname/address lookups and resolution
  *
- * locate the originating host
+ * Copyright (c) 1987-2011 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.
  */
 
-#ifdef DLL_EXPORT
-#define IN_LIBCIT
-#endif
-
 #include "sysdep.h"
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <ctype.h>
 #include <signal.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <arpa/inet.h>
 #include <limits.h>
 #include <netdb.h>
 #include <string.h>
+#include <errno.h>
+#include <syslog.h>
+#include <libcitadel.h>
 #include "citadel.h"
 #include "server.h"
-#include "dynloader.h"
 #include "locate_host.h"
 #include "sysdep_decls.h"
 #include "config.h"
-#include "tools.h"
+#include "domain.h"
+#include "context.h"
+#include "ctdl_module.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
+
+/** 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
 
-void locate_host(char *tbuf, const struct in_addr *addr)
+/** 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);
 
-	lprintf(9, "locate_host() called\n");
+	tbuf[0] = 0;
+	abuf[0] = 0;
 
-#ifdef HAVE_NONREENTRANT_NETDB
-	begin_critical_section(S_NETDB);
-#endif
+	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);
 
-	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, 63);
-			goto end;
+	/* 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");
 		}
-	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 *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);
+	}
 
-	tbuf[63] = 0;
-	lprintf(9, "locate_host() exiting\n");
+	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);
 }