1 files changed, 142 insertions, 0 deletions
diff --git a/src/smtp/smtp_unalias.c b/src/smtp/smtp_unalias.c
new file mode 100644
index 0000000..1c4d34d
--- /dev/null
+++ b/src/smtp/smtp_unalias.c
@@ -0,0 +1,142 @@
+/*++
+/* 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