1 files changed, 69 insertions, 0 deletions
diff --git a/src/dns/dns_strerror.c b/src/dns/dns_strerror.c
new file mode 100644
index 0000000..9e56d3b
--- /dev/null
+++ b/src/dns/dns_strerror.c
@@ -0,0 +1,69 @@
+/*++
+/* NAME
+/*	dns_strerror 3
+/* SUMMARY
+/*	name service lookup error code to string
+/* SYNOPSIS
+/*	#include <dhs.h>
+/*
+/*	const char *dns_strerror(code)
+/*	int	code;
+/* DESCRIPTION
+/*	dns_strerror() maps a name service lookup error to printable string.
+/*	The result is for read-only purposes, and unknown codes share a
+/*	common string buffer.
+/* 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 <netdb.h>
+
+/* Utility library. */
+
+#include <vstring.h>
+
+/* DNS library. */
+
+#include "dns.h"
+
+ /*
+  * Mapping from error code to printable string. The herror() routine does
+  * something similar, but has output only to the stderr stream.
+  */
+struct dns_error_map {
+    unsigned error;
+    const char *text;
+};
+
+static struct dns_error_map dns_error_map[] = {
+    HOST_NOT_FOUND, "Host not found",
+    TRY_AGAIN, "Host not found, try again",
+    NO_RECOVERY, "Non-recoverable error",
+    NO_DATA, "Host found but no data record of requested type",
+};
+
+/* dns_strerror - map resolver error code to printable string */
+
+const char *dns_strerror(unsigned error)
+{
+    static VSTRING *unknown = 0;
+    unsigned i;
+
+    for (i = 0; i < sizeof(dns_error_map) / sizeof(dns_error_map[0]); i++)
+	if (dns_error_map[i].error == error)
+	    return (dns_error_map[i].text);
+    if (unknown == 0)
+	unknown = vstring_alloc(sizeof("Unknown error XXXXXX"));
+    vstring_sprintf(unknown, "Unknown error %u", error);
+    return (vstring_str(unknown));
+}