From 8a0b284740c7f49d709e76796c439920d243fdde Mon Sep 17 00:00:00 2001
From: Milos Mileusnic <mileusna@gmail.com>
Date: Sat, 27 Mar 2021 20:07:51 +0100
Subject: [PATCH]  fix #1, fix #2; Add DNSServer settings, modifies dnsQuest

---
 README.md   |  9 ++++++++-
 resolver.go | 14 ++++++++++----
 spf_test.go | 11 ++++++++++-
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index c6d0b19..1f43ffb 100644
--- a/README.md
+++ b/README.md
@@ -17,9 +17,16 @@ import (
 )
 
 func main() {
+    // optional, set DNS server which will be used by resolver.
+    // Default is Google's 8.8.8.8:53
+    spf.DNSServer = "1.1.1.1:53"
+
     ip := net.ParseIP("123.123.123.123")
     r := spf.CheckHost(ip, "domain.com", "name@domain.com", "");
     // returns spf check result
-    // "pass" / "fail" / "softfail" / "neutral" / "none" / "temperror" / "permerror"
+    // "PASS" / "FAIL" / "SOFTFAIL" / "NEUTRAL" / "NONE" / "TEMPERROR" / "PERMERROR"
+
+    // if you only need to retrive SPF record as string from DNS
+    spfRecord, _ := spf.LookupSPF("domain.com")
 }
 ```
\ No newline at end of file
diff --git a/resolver.go b/resolver.go
index 565e3d0..1dc4648 100644
--- a/resolver.go
+++ b/resolver.go
@@ -8,9 +8,14 @@ import (
 	"github.com/miekg/dns"
 )
 
-// LookupSPF returns spf txt record
-// if no records found or more than one record found, r value will be set accordingly to None or PermError
-// If dns lookup faild, r will be set to TempError
+// DNSServer global var to use for resolver in format <ip>:<port>
+// By default it uses Google's 8.8.8.8:53
+// Misconfigured DNSServer will cause SPF checks to return TEMPERROR.
+var DNSServer = "8.8.8.8:53"
+
+// LookupSPF returns spf txt record.
+// if no records found or more than one record found, r value will be set accordingly to None or PermError.
+// If dns lookup faild, r will be set to TempError.
 func LookupSPF(domain string) (spf string, r Result) {
 	txts, err := lookupTXT(domain)
 	if err != nil {
@@ -128,9 +133,10 @@ func dnsQuest(d string, t uint16) (r *dns.Msg, rtt time.Duration, err error) {
 	m.Id = dns.Id()
 	m.SetQuestion(dns.Fqdn(d), t)
 	m.RecursionDesired = true
+	m.SetEdns0(4096, false)
 
 	c := new(dns.Client)
-	return c.Exchange(m, "8.8.8.8:53")
+	return c.Exchange(m, DNSServer)
 }
 
 func init() {
diff --git a/spf_test.go b/spf_test.go
index d1b68ba..5be218d 100644
--- a/spf_test.go
+++ b/spf_test.go
@@ -55,7 +55,7 @@ func TestCheckHost(t *testing.T) {
 		newTestData(ip, "gmail.com", "mileusna@gmail.com", "", spf.Softfail),
 		newTestData(ip, "hotmail.com", "mileusna@hotmail.com", "", spf.Softfail),
 		newTestData(ip2, "netmark.rs", "milos@netmark.rs", "", spf.Pass),
-		newTestData(ip2, "naslovi.net", "milos@naslovi.net", "", spf.Softfail),
+		newTestData(ip2, "naslovi.net", "milos@naslovi.net", "", spf.Pass),
 	}
 
 	for _, d := range data {
@@ -63,7 +63,16 @@ func TestCheckHost(t *testing.T) {
 			t.Fatal("CheckHost", d.ip, d.domain, d.sender, "should", d.result, "returned:", r)
 		}
 	}
+}
+
+func TestDNSSettings(t *testing.T) {
+	spf.DNSServer = "127.2.2.1:53"
+
+	if spf.CheckHost(net.ParseIP("87.237.204.223"), "naslovi.net", "milos@naslovi.net", "") != "TEMPERROR" {
+		t.Error("Invalid DNS configuration should return TEMPERROR")
+	}
 
+	spf.DNSServer = "8.8.8.8:53"
 }
 
 func TestMacro(t *testing.T) {