-#include <stdlib.h>
-#include <unistd.h>
-#include <netinet/in.h>
+/*
+ * DNS lookup for SMTP sender
+ *
+ * Copyright (c) 1987-2021 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 <stdio.h>
+#include <syslog.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 <libcitadel.h>
#include "sysdep_decls.h"
+#include "citadel.h"
#include "domain.h"
+#include "internet_addressing.h"
+
+
+/*
+ * get_hosts() checks the Internet configuration for various types of
+ * entries and returns them in the same format as getmx() does -- fill the
+ * buffer with a delimited list of hosts and return the number of hosts.
+ *
+ * This is used to fetch MX smarthosts, SpamAssassin hosts, etc.
+ */
+int get_hosts(char *mxbuf, char *rectype) {
+ int config_lines;
+ int i;
+ char buf[256];
+ char host[256], type[256];
+ int total_smarthosts = 0;
+
+ if (inetcfg == NULL) return(0);
+ strcpy(mxbuf, "");
+
+ config_lines = num_tokens(inetcfg, '\n');
+ for (i=0; i<config_lines; ++i) {
+ extract_token(buf, inetcfg, i, '\n', sizeof buf);
+ extract_token(host, buf, 0, '|', sizeof host);
+ extract_token(type, buf, 1, '|', sizeof type);
+
+ if (!strcasecmp(type, rectype)) {
+ strcat(mxbuf, host);
+ strcat(mxbuf, "|");
+ ++total_smarthosts;
+ }
+ }
+
+ return(total_smarthosts);
+}
+
+
+/*
+ * Compare the preference of two MX records. First check by the actual
+ * number listed in the MX record. If they're identical, randomize the
+ * result.
+ */
+int mx_compare_pref(const void *mx1, const void *mx2) {
+ int pref1;
+ int pref2;
+
+ pref1 = ((const struct mx *)mx1)->pref;
+ pref2 = ((const struct mx *)mx2)->pref;
+
+ if (pref1 > pref2) {
+ return(1);
+ }
+ else if (pref1 < pref2) {
+ return(0);
+ }
+ else {
+ return(rand() % 2);
+ }
+}
-#define SMART_HOST "gatekeeper.wdcs.com"
/*
* getmx()
*
*/
int getmx(char *mxbuf, char *dest) {
- char answer[1024];
- int ret;
+#ifdef HAVE_RESOLV_H
+ union {
+ u_char bytes[1024];
+ HEADER header;
+ } answer;
+#endif
+ int ret;
+ unsigned char *startptr, *endptr, *ptr;
+ char expanded_buf[1024];
+ unsigned short pref, type;
+ int n = 0;
+ int qdcount;
+
+ struct mx *mxrecs = NULL;
+ int num_mxrecs = 0;
/* If we're configured to send all mail to a smart-host, then our
* job here is really easy.
*/
- if (1) { /* FIX */
- strcpy(mxbuf, SMART_HOST);
- return(1);
+ n = get_hosts(mxbuf, "smarthost");
+ if (n > 0) {
+ return(n);
}
- /* No smart-host? Look up the best MX for a site.
+ /*
+ * No smart-host? Look up the best MX for a site.
+ * Make a call to the resolver library.
*/
- ret = res_query(
- dest,
- C_IN, T_MX, answer, sizeof(answer) );
- lprintf(9, "res_query() returned %d\n", ret);
+ ret = res_query(dest, C_IN, T_MX, (unsigned char *)answer.bytes, sizeof(answer));
if (ret < 0) {
- lprintf(5, "No MX found\n");
- return(0);
+ mxrecs = malloc(sizeof(struct mx));
+ mxrecs[0].pref = 0;
+ strcpy(mxrecs[0].host, dest);
+ num_mxrecs = 1;
+ }
+ else {
+ /* If we had to truncate, shrink the number to avoid fireworks */
+ if (ret > sizeof(answer)) {
+ ret = sizeof(answer);
+ }
+
+ startptr = &answer.bytes[0]; // start and end of buffer
+ endptr = &answer.bytes[ret];
+ ptr = startptr + HFIXEDSZ; // advance past header
+
+ for (qdcount = ntohs(answer.header.qdcount); qdcount--; ptr += ret + QFIXEDSZ) {
+ if ((ret = dn_skipname(ptr, endptr)) < 0) {
+ syslog(LOG_DEBUG, "domain: dn_skipname error");
+ return(0);
+ }
+ }
+
+ while(1) {
+ TRACE;
+ memset(expanded_buf, 0, sizeof(expanded_buf));
+ ret = dn_expand(startptr, endptr, ptr, expanded_buf, sizeof(expanded_buf));
+ if (ret < 0) break;
+ ptr += ret;
+
+ GETSHORT(type, ptr);
+ ptr += INT16SZ + INT32SZ;
+ GETSHORT(n, ptr);
+
+ syslog(LOG_DEBUG, "\033[35mgetmx: found record of type %d and length %d\033[0m", type, n);
+ if (type != T_MX) {
+ ptr += n;
+ }
+
+ else {
+ GETSHORT(pref, ptr);
+ ret = dn_expand(startptr, endptr, ptr, expanded_buf, sizeof(expanded_buf));
+ ptr += ret;
+
+ ++num_mxrecs;
+ if (mxrecs == NULL) {
+ mxrecs = malloc(sizeof(struct mx));
+ }
+ else {
+ mxrecs = realloc(mxrecs, (sizeof(struct mx) * num_mxrecs) );
+ }
+
+ mxrecs[num_mxrecs - 1].pref = pref;
+ strcpy(mxrecs[num_mxrecs - 1].host, expanded_buf);
+ }
+ }
}
- /* If we had to truncate, shrink the number to avoid fireworks */
- if (ret > sizeof(answer))
- ret = sizeof(answer);
+ /* Sort the MX records by preference */
+ if (num_mxrecs > 1) {
+ qsort(mxrecs, num_mxrecs, sizeof(struct mx), mx_compare_pref);
+ }
+
+ strcpy(mxbuf, "");
+ for (n=0; n<num_mxrecs; ++n) {
+ syslog(LOG_DEBUG, "\033[35mgetmx: %d : <%s>\033[0m", n, mxrecs[n].host);
+ strcat(mxbuf, mxrecs[n].host);
+ strcat(mxbuf, "|");
+ }
+ free(mxrecs);
- /* FIX not done yet */
- return(0);
+ /*
+ * Append any fallback smart hosts we have configured.
+ */
+ num_mxrecs += get_hosts(&mxbuf[strlen(mxbuf)], "fallbackhost");
+ return(num_mxrecs);
}
projects / citadel.git / blobdiff