-#include <stdlib.h>
-#include <unistd.h>
-#include <string.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 "server.h"
-#include "tools.h"
#include "internet_addressing.h"
/*
- * get_smarthosts() checks the Internet configuration for "smarthost"
+ * 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_smarthosts(char *mxbuf) {
+int get_hosts(char *mxbuf, char *rectype) {
int config_lines;
int i;
char buf[256];
config_lines = num_tokens(inetcfg, '\n');
for (i=0; i<config_lines; ++i) {
- extract_token(buf, inetcfg, i, '\n');
- extract_token(host, buf, 0, '|');
- extract_token(type, buf, 1, '|');
+ 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, "smarthost")) {
+ if (!strcasecmp(type, rectype)) {
strcat(mxbuf, host);
strcat(mxbuf, "|");
++total_smarthosts;
}
-
-
/*
- * sort_mxrecs()
- *
- * Sort a pile of MX records (struct mx, definted in domain.h) by preference
- *
+ * 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.
*/
-void sort_mxrecs(struct mx *mxrecs, int num_mxrecs) {
- int a, b;
- struct mx hold1, hold2;
+int mx_compare_pref(const void *mx1, const void *mx2) {
+ int pref1;
+ int pref2;
- if (num_mxrecs < 2) return;
+ pref1 = ((const struct mx *)mx1)->pref;
+ pref2 = ((const struct mx *)mx2)->pref;
- /* do the sort */
- for (a = num_mxrecs - 2; a >= 0; --a) {
- for (b = 0; b <= a; ++b) {
- if (mxrecs[b].pref > mxrecs[b+1].pref) {
-
- memcpy(&hold1, &mxrecs[b], sizeof(struct mx));
- memcpy(&hold2, &mxrecs[b+1], sizeof(struct mx));
- memcpy(&mxrecs[b], &hold2, sizeof(struct mx));
- memcpy(&mxrecs[b+1], &hold1, sizeof(struct mx));
- }
- }
+ if (pref1 > pref2) {
+ return(1);
+ }
+ else if (pref1 < pref2) {
+ return(0);
+ }
+ else {
+ return(rand() % 2);
}
}
-
/*
* getmx()
*
*
*/
int getmx(char *mxbuf, char *dest) {
- char answer[1024];
+
+#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;
- HEADER *hp;
int qdcount;
+ Array *mxrecords = NULL;
+ struct mx mx;
- 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.
- */
- n = get_smarthosts(mxbuf);
- if (n > 0) return(n);
-
- /*
- * No smart-host? Look up the best MX for a site.
- */
- ret = res_query(
- dest,
- C_IN, T_MX, (unsigned char *)answer, sizeof(answer) );
-
- if (ret < 0) {
- lprintf(5, "No MX found\n");
- return(0);
+ // If we're configured to send all mail to a smart-host, then our job here is really easy -- just return those.
+ n = get_hosts(mxbuf, "smarthost");
+ if (n > 0) {
+ return(n);
}
- /* If we had to truncate, shrink the number to avoid fireworks */
- if (ret > sizeof(answer))
- ret = sizeof(answer);
+ mxrecords = array_new(sizeof(struct mx));
- hp = (HEADER *)&answer[0];
- startptr = &answer[0]; /* start and end of buffer */
- endptr = &answer[ret];
- ptr = startptr + HFIXEDSZ; /* advance past header */
+ // 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, (unsigned char *)answer.bytes, sizeof(answer));
- for (qdcount = ntohs(hp->qdcount); qdcount--; ptr += ret + QFIXEDSZ) {
- if ((ret = dn_skipname(ptr, endptr)) < 0) {
- lprintf(9, "dn_skipname error\n");
- return(0);
- }
+ if (ret < 0) {
+ mx.pref = 0;
+ strcpy(mx.host, dest);
+ array_append(mxrecords, &mx);
}
-
- while(1) {
- 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);
-
- if (type != T_MX) {
- ptr += n;
+ else {
+ if (ret > sizeof(answer)) { // If we had to truncate, shrink the number to avoid fireworks
+ ret = sizeof(answer);
}
- else {
- GETSHORT(pref, ptr);
- ret = dn_expand(startptr,
- endptr,
- ptr,
- expanded_buf,
- sizeof(expanded_buf)
- );
+ 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) {
+ memset(expanded_buf, 0, sizeof(expanded_buf));
+ ret = dn_expand(startptr, endptr, ptr, expanded_buf, sizeof(expanded_buf));
+ if (ret < 0) break;
ptr += ret;
-
- ++num_mxrecs;
- if (mxrecs == NULL) {
- mxrecs = mallok(sizeof(struct mx));
+
+ GETSHORT(type, ptr);
+ ptr += INT16SZ + INT32SZ;
+ GETSHORT(n, ptr);
+
+ if (type != T_MX) {
+ ptr += n;
}
+
else {
- mxrecs = reallok(mxrecs,
- (sizeof(struct mx) * num_mxrecs) );
+ GETSHORT(pref, ptr);
+ ret = dn_expand(startptr, endptr, ptr, expanded_buf, sizeof(expanded_buf));
+ ptr += ret;
+
+ mx.pref = pref;
+ strcpy(mx.host, expanded_buf);
+ array_append(mxrecords, &mx);
}
-
- mxrecs[num_mxrecs - 1].pref = pref;
- strcpy(mxrecs[num_mxrecs - 1].host, expanded_buf);
}
}
- sort_mxrecs(mxrecs, num_mxrecs);
+ // Sort the MX records by preference
+ if (array_len(mxrecords) > 1) {
+ array_sort(mxrecords, mx_compare_pref);
+ }
+ int num_mxrecs = array_len(mxrecords);
strcpy(mxbuf, "");
for (n=0; n<num_mxrecs; ++n) {
- strcat(mxbuf, mxrecs[n].host);
+ strcat(mxbuf, ((struct mx *)array_get_element_at(mxrecords, n))->host);
strcat(mxbuf, "|");
}
- phree(mxrecs);
+ array_free(mxrecords);
+
+ // Append any fallback smart hosts we have configured.
+ num_mxrecs += get_hosts(&mxbuf[strlen(mxbuf)], "fallbackhost");
return(num_mxrecs);
}
projects / citadel.git / blobdiff