From b4173c3374dd5ac45652453bebd0406c7d551f33 Mon Sep 17 00:00:00 2001
From: Shumon Huque <shuque@gmail.com>
Date: Wed, 27 May 2020 15:14:29 -0400
Subject: [PATCH] ConnectByName() function.

---
 byname.go      | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++
 byname_test.go | 31 ++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 byname.go
 create mode 100644 byname_test.go

diff --git a/byname.go b/byname.go
new file mode 100644
index 0000000..35327c2
--- /dev/null
+++ b/byname.go
@@ -0,0 +1,56 @@
+package dane
+
+import (
+	"crypto/tls"
+	"fmt"
+)
+
+//
+// ConnectByName takes a hostname and port, resolves the addresses for
+// the hostname (IPv6 followed by IPv4), and then attempts to connect to
+// them and establish TLS. It returns a TLS connection and dane config for
+// the first address that succeeds.
+//
+// Uses a default DANE configuration. For a custom DANE configuration,
+// use the DialTLS or DialStartTLS functions instead.
+//
+func ConnectByName(hostname string, port int) (*tls.Conn, *Config, error) {
+
+	var conn *tls.Conn
+
+	resolver, err := GetResolver("")
+	if err != nil {
+		return nil, nil, fmt.Errorf("Error obtaining resolver address: %s", err.Error())
+	}
+
+	tlsa, err := GetTLSA(resolver, hostname, port)
+	if err != nil {
+		return nil, nil, fmt.Errorf("GetTLSA: %s", err.Error())
+	}
+
+	needSecure := (tlsa != nil)
+	iplist, err := GetAddresses(resolver, hostname, needSecure)
+	if err != nil {
+		return nil, nil, fmt.Errorf("GetAddresses: %s", err.Error())
+	}
+
+	if len(iplist) == 0 {
+		return nil, nil, fmt.Errorf("No addresses found")
+	}
+
+	for _, ip := range iplist {
+
+		server := NewServer(hostname, ip, port)
+		config := NewConfig()
+		config.SetServer(server)
+		config.SetTLSA(tlsa)
+		conn, err = DialTLS(config)
+		if err != nil {
+			fmt.Printf("Connection failed to %s: %s\n", server.Address(), err.Error())
+			continue
+		}
+		return conn, config, err
+	}
+
+	return conn, nil, fmt.Errorf("Failed to connect to any server address")
+}
diff --git a/byname_test.go b/byname_test.go
new file mode 100644
index 0000000..b5c61f7
--- /dev/null
+++ b/byname_test.go
@@ -0,0 +1,31 @@
+package dane
+
+/*
+ * Note: these test routines may not work unless you adapt this file
+ * to use validating DNS resolvers and appropriately configured DANE TLS
+ * servers you have access to.
+ */
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestConnectByName(t *testing.T) {
+
+	var hostname = "www.example.com"
+	var port = 443
+
+	conn, config, err := ConnectByName(hostname, port)
+	if err != nil {
+		t.Fatalf("%s\n", err.Error())
+	}
+	fmt.Printf("ConnectByName: Success connecting to %s %d\n", hostname, port)
+	if config.Okdane {
+		fmt.Printf("DANE OK\n")
+	} else if config.Okpkix {
+		fmt.Printf("PKIX OK\n")
+	}
+	fmt.Printf("\n")
+	conn.Close()
+}