From 4fbbabc2705e0c7320516b673f855494d48ec81d Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Fri, 25 Oct 1996 18:08:43 +0000
Subject: Initial revision

svn path=/trunk/; revision=379
---
 mx.h    | 13 +++++++++++
 mxget.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 mx.h
 create mode 100644 mxget.c

diff --git a/mx.h b/mx.h
new file mode 100644
index 00000000..5e2824c0
--- /dev/null
+++ b/mx.h
@@ -0,0 +1,13 @@
+/* mx.h -- name-to-preference association for MX records */
+
+struct mxentry
+{
+    char	*name;
+    int		pref;
+};
+
+#ifdef HAVE_PROTOTYPES
+extern int getmxrecords(char *, int, struct mxentry *);
+#endif /* HAVE_PROTOTYPES */
+
+/* mx.h ends here */
diff --git a/mxget.c b/mxget.c
new file mode 100644
index 00000000..081c20f6
--- /dev/null
+++ b/mxget.c
@@ -0,0 +1,81 @@
+/*
+ * mxget.c -- fetch MX records for given DNS name
+ *
+ * Copyright 1996 by Eric S. Raymond
+ * All rights reserved.
+ * For license terms, see the file COPYING in this directory.
+ */
+
+#include <config.h>
+#ifdef HAVE_GETHOSTBYNAME
+#include <netdb.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/nameser.h>
+#include <resolv.h>
+#include "mx.h"
+
+/*
+ * This ought to be in the bind library.  It's adapted from sendmail.
+ */
+
+int getmxrecords(name, nmx, pmx)
+/* get MX records for given host */
+char *name;
+int nmx;
+struct mxentry *pmx;
+{
+    unsigned char answer[PACKETSZ], MXHostBuf[PACKETSZ], *eom, *cp, *bp;
+    int n, ancount, qdcount, buflen, type, pref, ind;
+    HEADER *hp;
+
+    n = res_search(name,C_IN,T_MX,(unsigned char*)&answer, sizeof(answer));
+    if (n == -1)
+	return(-1);
+
+    hp = (HEADER *)&answer;
+    cp = answer + HFIXEDSZ;
+    eom = answer + n;
+    for (qdcount = ntohs(hp->qdcount); qdcount--; cp += n + QFIXEDSZ)
+	if ((n = dn_skipname(cp, eom)) < 0)
+	    return(-1);
+    buflen = sizeof(MXHostBuf) - 1;
+    bp = MXHostBuf;
+    ind = 0;
+    ancount = ntohs(hp->ancount);
+    while (--ancount >= 0 && cp < eom)
+    {
+	if ((n = dn_expand(answer, eom, cp, bp, buflen)) < 0)
+	    break;
+	cp += n;
+	GETSHORT(type, cp);
+	cp += INT16SZ + INT32SZ;
+	GETSHORT(n, cp);
+	if (type != T_MX)
+	{
+	    cp += n;
+	    continue;
+	}
+	GETSHORT(pref, cp);
+	if ((n = dn_expand(answer, eom, cp, bp, buflen)) < 0)
+	    break;
+	cp += n;
+
+	pmx[ind].name = bp;
+	pmx[ind].pref = pref;
+	if (++ind > nmx)
+	    break;
+
+	n = strlen(bp);
+	bp += n;
+	*bp++ = '\0';
+
+
+	buflen -= n + 1;
+    }
+
+    return(ind);
+}
+#endif /* HAVE_GETHOSTBYNAME */
+
+/* mxget.c ends here */
-- 
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