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-rw-r--r--src/smtp/smtp_unalias.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/src/smtp/smtp_unalias.c b/src/smtp/smtp_unalias.c
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+/*++
+/* NAME
+/* smtp_unalias 3
+/* SUMMARY
+/* replace host/domain alias by official name
+/* SYNOPSIS
+/* #include "smtp.h"
+/*
+/* const char *smtp_unalias_name(name)
+/* const char *name;
+/*
+/* VSTRING *smtp_unalias_addr(result, addr)
+/* VSTRING *result;
+/* const char *addr;
+/* DESCRIPTION
+/* smtp_unalias_name() looks up A or MX records for the specified
+/* name and returns the official name provided in the reply. When
+/* no A or MX record is found, the result is a copy of the input.
+/* In order to improve performance, smtp_unalias_name() remembers
+/* results in a private cache, so a name is looked up only once.
+/*
+/* smtp_unalias_addr() returns the input address, which is in
+/* RFC 821 quoted form, after replacing the domain part by the
+/* official name as found by smtp_unalias_name(). When the input
+/* contains no domain part, the result is a copy of the input.
+/* LICENSE
+/* .ad
+/* .fi
+/* The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/* Wietse Venema
+/* IBM T.J. Watson Research
+/* P.O. Box 704
+/* Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <netdb.h>
+#include <string.h>
+
+/* Utility library. */
+
+#include <htable.h>
+#include <vstring.h>
+#include <msg.h>
+
+/* DNS library. */
+
+#include <dns.h>
+
+/* Application-specific. */
+
+#include "smtp.h"
+
+static int smtp_unalias_flags;
+
+/* smtp_unalias_name - look up the official host or domain name. */
+
+const char *smtp_unalias_name(const char *name)
+{
+ static HTABLE *cache;
+ VSTRING *fqdn;
+ char *result;
+
+ if (*name == '[')
+ return (name);
+
+ /*
+ * Initialize the cache on the fly. The smtp client is designed to exit
+ * after servicing a limited number of requests, so there is no need to
+ * prevent the cache from growing too large, or to expire old entries.
+ */
+ if (cache == 0)
+ cache = htable_create(10);
+
+ /*
+ * Look up the fqdn. If none is found use the query name instead, so that
+ * we won't lose time looking up the same bad name again.
+ */
+ if ((result = htable_find(cache, name)) == 0) {
+ fqdn = vstring_alloc(10);
+ if (dns_lookup_l(name, smtp_unalias_flags, (DNS_RR **) 0, fqdn,
+ (VSTRING *) 0, DNS_REQ_FLAG_NONE, T_MX, T_A,
+#ifdef HAS_IPV6
+ T_AAAA,
+#endif
+ 0) != DNS_OK)
+ vstring_strcpy(fqdn, name);
+ htable_enter(cache, name, result = vstring_export(fqdn));
+ }
+ return (result);
+}
+
+/* smtp_unalias_addr - rewrite aliases in domain part of address */
+
+VSTRING *smtp_unalias_addr(VSTRING *result, const char *addr)
+{
+ char *at;
+ const char *fqdn;
+
+ if ((at = strrchr(addr, '@')) == 0 || at[1] == 0) {
+ vstring_strcpy(result, addr);
+ } else {
+ fqdn = smtp_unalias_name(at + 1);
+ vstring_strncpy(result, addr, at - addr + 1);
+ vstring_strcat(result, fqdn);
+ }
+ return (result);
+}
+
+#ifdef TEST
+
+ /*
+ * Test program - read address from stdin, print result on stdout.
+ */
+
+#include <vstring_vstream.h>
+
+int main(int unused_argc, char **unused_argv)
+{
+ VSTRING *addr = vstring_alloc(10);
+ VSTRING *result = vstring_alloc(10);
+
+ smtp_unalias_flags |= RES_DEBUG;
+
+ while (vstring_fgets_nonl(addr, VSTREAM_IN)) {
+ smtp_unalias_addr(result, vstring_str(addr));
+ vstream_printf("%s -> %s\n", vstring_str(addr), vstring_str(result));
+ vstream_fflush(VSTREAM_OUT);
+ }
+ vstring_free(addr);
+ vstring_free(result);
+ return (0);
+}
+
+#endif