Moved default authenticator into internal package.

Fixed error in default authenticator where it tried to register the same http handler multiple times.
Added config decorator functions WithDefaultOAUTH, WithClientCredentials
Signed-off-by: Raymond Cypher <raymond.cypher@databricks.com>

Author: rcypher-databricks

auth/oauth/dev/dev.go

@@ -20,11 +20,12 @@ func GetEndpoint(ctx context.Context, hostName string) (oauth2.Endpoint, error)
 	}
 
 	cloud := InferCloudFromHost(hostName)
-	if cloud == unknown {
+
+	if cloud == Unknown {
 		return oauth2.Endpoint{}, errors.New("unsupported cloud type")
 	}
 
-	if cloud == azure {
+	if cloud == Azure {
 		authURL := fmt.Sprintf("https://%s/oidc/oauth2/v2.0/authorize", hostName)
 		tokenURL := fmt.Sprintf("https://%s/oidc/oauth2/v2.0/token", hostName)
 		return oauth2.Endpoint{AuthURL: authURL, TokenURL: tokenURL}, nil
@@ -50,7 +51,7 @@ func GetScopes(hostName string, scopes []string) []string {
 	}
 
 	cloudType := InferCloudFromHost(hostName)
-	if cloudType == azure {
+	if cloudType == Azure {
 		userImpersonationScope := fmt.Sprintf("%s/user_impersonation", azureEnterpriseAppId)
 		if !hasScope(scopes, userImpersonationScope) {
 			scopes = append(scopes, userImpersonationScope)
@@ -86,34 +87,47 @@ var databricksAzureDomains []string = []string{
 
 var databricksGCPDomains []string = []string{".gcp.databricks.com"}
 
-type cloudType int
+type CloudType int
 
 const (
-	aws = iota
-	azure
-	gcp
-	unknown
+	AWS = iota
+	Azure
+	GCP
+	Unknown
 )
 
-func InferCloudFromHost(hostname string) cloudType {
+func (cl CloudType) String() string {
+	switch cl {
+	case AWS:
+		return "AWS"
+	case Azure:
+		return "Azure"
+	case GCP:
+		return "GCP"
+	}
+
+	return "Unknown"
+}
+
+func InferCloudFromHost(hostname string) CloudType {
 
 	for _, d := range databricksAzureDomains {
 		if strings.Contains(hostname, d) {
-			return azure
+			return Azure
 		}
 	}
 
 	for _, d := range databricksAWSDomains {
 		if strings.Contains(hostname, d) {
-			return aws
+			return AWS
 		}
 	}
 
 	for _, d := range databricksGCPDomains {
 		if strings.Contains(hostname, d) {
-			return gcp
+			return GCP
 		}
 	}
 
-	return unknown
+	return Unknown
 }

auth/oauth/oauth.go

@@ -6,13 +6,15 @@ import (
 	"strings"
 
 	"github.com/databricks/databricks-sql-go/auth/oauth"
-	"github.com/databricks/databricks-sql-go/auth/oauth/pkce"
+	"github.com/databricks/databricks-sql-go/internal/auth/oauth/pkce"
 	"golang.org/x/oauth2"
 )
 
 func GetConfig(ctx context.Context, hostName, clientID, clientSecret, callbackURL string, scopes []string) (oauth2.Config, error) {
+	// Add necessary scopes for AWS or Azure
 	scopes = oauth.GetScopes(hostName, scopes)
 
+	// Get the endpoint based on the host name
 	endpoint, err := oauth.GetEndpoint(ctx, hostName)
 	if err != nil {
 		return oauth2.Config{}, fmt.Errorf("could not lookup provider details: %w", err)

auth/oauth/u2m/u2m.go

@@ -9,9 +9,10 @@ import (
 	"time"
 
 	"github.com/databricks/databricks-sql-go/auth"
-	"github.com/databricks/databricks-sql-go/auth/pat"
 	"github.com/databricks/databricks-sql-go/driverctx"
 	dbsqlerr "github.com/databricks/databricks-sql-go/errors"
+	"github.com/databricks/databricks-sql-go/internal/auth/oauth/m2m"
+	"github.com/databricks/databricks-sql-go/internal/auth/pat"
 	"github.com/databricks/databricks-sql-go/internal/cli_service"
 	"github.com/databricks/databricks-sql-go/internal/client"
 	"github.com/databricks/databricks-sql-go/internal/config"
@@ -259,3 +260,12 @@ func WithMaxDownloadThreads(numThreads int) connOption {
 		c.MaxDownloadThreads = numThreads
 	}
 }
+
+func WithClientCredentials(clientID, clientSecret string) connOption {
+	return func(c *config.Config) {
+		if clientID != "" && clientSecret != "" {
+			authr := m2m.NewClient(clientID, clientSecret, c.Host)
+			c.Authenticator = authr
+		}
+	}
+}

connector.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/databricks/databricks-sql-go/auth/pat"
+	"github.com/databricks/databricks-sql-go/internal/auth/pat"
 	"github.com/databricks/databricks-sql-go/internal/config"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"

connector_test.go

@@ -4,7 +4,7 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/databricks/databricks-sql-go/auth/pat"
+	"github.com/databricks/databricks-sql-go/internal/auth/pat"
 	"github.com/databricks/databricks-sql-go/internal/config"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"

driver_test.go

@@ -22,6 +22,7 @@ const (
 	ErrInvalidURL      = "invalid URL"
 
 	ErrNoAuthenticationMethod = "no authentication method set"
+	ErrNoDefaultAuthenticator = "unable to create default authenticator"
 	ErrInvalidDSNFormat       = "invalid DSN: invalid format"
 	ErrInvalidDSNPort         = "invalid DSN: invalid DSN port"
 	ErrInvalidDSNPATIsEmpty   = "invalid DSN: empty token"