+/*
+ * checkalias.c -- check to see if two hostnames or IP addresses are equivalent
+ *
+ * Copyright 1997 by Eric S. Raymond
+ * For license terms, see the file COPYING in this directory.
+ */
+#include "config.h"
+#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
+#ifdef HAVE_NET_SOCKET_H
+#include <net/socket.h>
+#else
#include <sys/socket.h>
+#endif
#include <netinet/in.h>
+#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
+#endif
#include <netdb.h>
+#include "i18n.h"
+#include "mx.h"
#include "fetchmail.h"
+#include "getaddrinfo.h"
+
+#define MX_RETRIES 3
+
+typedef unsigned char address_t[sizeof (struct in_addr)];
+
+#ifdef HAVE_RES_SEARCH
+static int getaddresses(struct addrinfo **result, const char *name)
+{
+ struct addrinfo hints;
+
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_socktype=SOCK_STREAM;
+ hints.ai_protocol=PF_UNSPEC;
+ hints.ai_family=AF_UNSPEC;
+ return fm_getaddrinfo(name, NULL, &hints, result);
+}
+
+/* XXX FIXME: doesn't detect if an IPv6-mapped IPv4 address
+ * matches a real IPv4 address */
+static int compareaddr(const struct addrinfo *a1, const struct addrinfo *a2)
+{
+ if (a1->ai_family != a2->ai_family) return FALSE;
+ if (a1->ai_addrlen != a2->ai_addrlen) return FALSE;
+ return (!memcmp(a1->ai_addr, a2->ai_addr, a1->ai_addrlen));
+}
-
-int is_ip_alias(const char *name1,const char *name2)
-/* Given two hostnames as arguments, returns TRUE if they
+static int is_ip_alias(const char *name1,const char *name2)
+/*
+ * Given two hostnames as arguments, returns TRUE if they
* have at least one IP address in common.
- * It is meant to be called by the is_host_alias() function in driver.c
* No check is done on errors returned by gethostbyname,
* the calling function does them.
*/
- {
-
- typedef unsigned char address_t[sizeof (struct in_addr)];
- typedef struct _address_e { struct _address_e *next;
- address_t address;
- } address_e;
-
- address_e *host_a_addr, *host_b_addr,*dummy_addr;
-
- int i;
-
- struct hostent *hp;
-
- char **p;
-
- hp = gethostbyname(name1);
-
- dummy_addr = (address_e *)NULL;
-
- for (i=0,p = hp->h_addr_list; *p != 0; i++,p++) {
- struct in_addr in;
- (void) memcpy(&in.s_addr, *p, sizeof (in.s_addr));
- host_a_addr = (address_e *)xmalloc(sizeof( address_e));
- memset (host_a_addr,0, sizeof (address_e));
- host_a_addr->next = dummy_addr;
- (void) memcpy(&host_a_addr->address, *p, sizeof (in.s_addr));
- dummy_addr = host_a_addr;
- }
-
-
- hp = gethostbyname(name2);
-
- dummy_addr = (address_e *)NULL;
-
- for (i=0,p = hp->h_addr_list; *p != 0; i++,p++) {
- struct in_addr in;
- (void) memcpy(&in.s_addr, *p, sizeof (in.s_addr));
- host_b_addr = (address_e *)xmalloc(sizeof( address_e));
- memset (host_b_addr,0, sizeof (address_e));
- host_b_addr->next = dummy_addr;
- (void) memcpy(&host_b_addr->address, *p, sizeof (in.s_addr));
- dummy_addr = host_b_addr;
- }
-
- while (host_a_addr) {
- while (host_b_addr) {
-
- if (!memcmp(host_b_addr->address,host_a_addr->address, sizeof (address_t))) return (TRUE);
-
- host_b_addr = host_b_addr->next;
- }
- host_a_addr = host_a_addr->next;
+{
+ int rc = FALSE;
+
+ struct addrinfo *res1 = NULL, *res2 = NULL, *ii, *ij;
+
+ if (getaddresses(&res1, name1))
+ goto found;
+
+ if (getaddresses(&res2, name2))
+ goto found;
+
+ for (ii = res1 ; ii ; ii = ii -> ai_next) {
+ for (ij = res2 ; ij ; ij = ij -> ai_next) {
+ if (compareaddr(ii, ij)) {
+ rc = TRUE;
+ goto found;
+ }
}
-return (FALSE);
+ }
+
+found:
+ if (res2)
+ fm_freeaddrinfo(res2);
+ if (res1)
+ fm_freeaddrinfo(res1);
+ return rc;
+}
+#endif
+
+int is_host_alias(const char *name, struct query *ctl, struct addrinfo **res)
+/* determine whether name is a DNS alias of the mailserver for this query */
+{
+#ifdef HAVE_RES_SEARCH
+ struct mxentry *mxp, *mxrecords;
+ int e;
+ struct addrinfo hints, *res_st;
+#endif
+ struct idlist *idl;
+ size_t namelen;
+
+ struct hostdata *lead_server =
+ ctl->server.lead_server ? ctl->server.lead_server : &ctl->server;
+
+ /*
+ * The first two checks are optimizations that will catch a good
+ * many cases.
+ *
+ * (1) check against the `true name' deduced from the poll label
+ * and the via option (if present) at the beginning of the poll cycle.
+ * Odds are good this will either be the mailserver's FQDN or a suffix of
+ * it with the mailserver's domain's default host name omitted.
+ *
+ * (2) Then check the rest of the `also known as'
+ * cache accumulated by previous DNS checks. This cache is primed
+ * by the aka list option.
+ *
+ * Any of these on a mail address is definitive. Only if the
+ * name doesn't match any is it time to call the bind library.
+ * If this happens odds are good we're looking at an MX name.
+ */
+ if (strcasecmp(lead_server->truename, name) == 0)
+ return(TRUE);
+ else if (str_in_list(&lead_server->akalist, name, TRUE))
+ return(TRUE);
+
+ /*
+ * Now check for a suffix match on the akalist. The theory here is
+ * that if the user says `aka netaxs.com', we actually want to match
+ * foo.netaxs.com and bar.netaxs.com.
+ */
+ namelen = strlen(name);
+ for (idl = lead_server->akalist; idl; idl = idl->next)
+ {
+ const char *ep;
+
+ /*
+ * Test is >= here because str_in_list() should have caught the
+ * equal-length case above. Doing it this way guarantees that
+ * ep[-1] is a valid reference.
+ */
+ if (strlen(idl->id) >= namelen)
+ continue;
+ ep = name + (namelen - strlen(idl->id));
+ /* a suffix led by . must match */
+ if (ep[-1] == '.' && !strcasecmp(ep, idl->id))
+ return(TRUE);
+ }
+
+ if (!ctl->server.dns)
+ return(FALSE);
+#ifndef HAVE_RES_SEARCH
+ (void)res;
+ return(FALSE);
+#else
+ /*
+ * The only code that calls the BIND library is here and in the
+ * start-of-run probe with gethostbyname(3) under ETRN/Kerberos.
+ *
+ * We know DNS service was up at the beginning of the run.
+ * If it's down, our nameserver has crashed. We don't want to try
+ * delivering the current message or anything else from the
+ * current server until it's back up.
+ */
+ memset(&hints, 0, sizeof hints);
+ hints.ai_family=AF_UNSPEC;
+ hints.ai_protocol=PF_UNSPEC;
+ hints.ai_socktype=SOCK_STREAM;
+ hints.ai_flags=AI_CANONNAME;
+
+ e = fm_getaddrinfo(name, NULL, &hints, res);
+ if (e == 0)
+ {
+ int rr = (strcasecmp(ctl->server.truename, (*res)->ai_canonname) == 0);
+ fm_freeaddrinfo(*res); *res = NULL;
+ if (rr)
+ goto match;
+ else if (ctl->server.checkalias && 0 == fm_getaddrinfo(ctl->server.truename, NULL, &hints, &res_st))
+ {
+ fm_freeaddrinfo(res_st);
+ if (outlevel >= O_DEBUG)
+ report(stdout, GT_("Checking if %s is really the same node as %s\n"),ctl->server.truename,name);
+ if (is_ip_alias(ctl->server.truename,name) == TRUE)
+ {
+ if (outlevel >= O_DEBUG)
+ report(stdout, GT_("Yes, their IP addresses match\n"));
+ goto match;
+ }
+ if (outlevel >= O_DEBUG)
+ report(stdout, GT_("No, their IP addresses don't match\n"));
+ return(FALSE);
+ } else {
+ return(FALSE);
+ }
+ }
+ else
+ switch (e)
+ {
+ case EAI_NONAME: /* specified host is unknown */
+ break;
+
+ default:
+ if (outlevel != O_SILENT)
+ report_complete(stdout, "\n"); /* terminate the progress message */
+ report(stderr,
+ GT_("nameserver failure while looking for '%s' during poll of %s: %s\n"),
+ name, ctl->server.pollname, gai_strerror(e));
+ ctl->errcount++;
+ break;
+ }
+
+ /*
+ * We're only here if DNS was OK but the gethostbyname() failed
+ * with a HOST_NOT_FOUND or NO_ADDRESS error.
+ * Search for a name match on MX records pointing to the server.
+ */
+ h_errno = 0;
+ if ((mxrecords = getmxrecords(name)) == (struct mxentry *)NULL)
+ {
+ switch (h_errno)
+ {
+ case HOST_NOT_FOUND: /* specified host is unknown */
+#ifdef NO_ADDRESS
+ case NO_ADDRESS: /* valid, but does not have an IP address */
+ return(FALSE);
+#endif
+ case NO_RECOVERY: /* non-recoverable name server error */
+ case TRY_AGAIN: /* temporary error on authoritative server */
+ default:
+ report(stderr,
+ GT_("nameserver failure while looking for `%s' during poll of %s.\n"),
+ name, ctl->server.pollname);
+ ctl->errcount++;
+ break;
+ }
+ } else {
+ for (mxp = mxrecords; mxp->name; mxp++)
+ if (strcasecmp(ctl->server.truename, mxp->name) == 0
+ || is_ip_alias(ctl->server.truename, mxp->name) == TRUE)
+ goto match;
+ return(FALSE);
+ match:;
+ }
+
+ /* add this name to relevant server's `also known as' list */
+ save_str(&lead_server->akalist, name, 0);
+ return(TRUE);
+#endif /* HAVE_RES_SEARCH */
}
+/* checkalias.c ends here */
projects / ~andy / fetchmail / blobdiff