Improve error handling when TTL is invalid (#106)

* Include a better error message if TTL is too large

* Don't print usage on error

* Allow ambiguous TTL error

cli/consts.go

@@ -12,7 +12,7 @@ var (
 
 const (
 	// DefaultTTL for requested credentials in hours
-	DefaultTTL uint = 8
+	DefaultTTL uint = 1
 	// DefaultTimeRemaining for new key requests in minutes
 	DefaultTimeRemaining  uint   = 5
 	LinuxAmd64BinaryName  string = "keyconjurer-linux-amd64"

cli/error.go

@@ -1,18 +1,22 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"strings"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws/awserr"
 )
 
 const (
-	ExitCodeTokensExpiredOrAbsent uint8 = 0x1
-	ExitCodeUndisclosedOktaError        = 0x2
-	ExitCodeAuthenticationError         = 0x3
-	ExitCodeConnectivityError           = 0x4
-	ExitCodeValueError                  = 0x5
-	ExitCodeAWSError                    = 0x6
-	ExitCodeUnknownError                = 0x7D
+	ExitCodeTokensExpiredOrAbsent int = 0x1
+	ExitCodeUndisclosedOktaError  int = 0x2
+	ExitCodeAuthenticationError   int = 0x3
+	ExitCodeConnectivityError     int = 0x4
+	ExitCodeValueError            int = 0x5
+	ExitCodeAWSError              int = 0x6
+	ExitCodeUnknownError          int = 0x7D
 )
 
 var (
@@ -25,25 +29,25 @@ var (
 
 type genericError struct {
 	Message  string
-	ExitCode uint8
+	ExitCode int
 }
 
 func (e genericError) Error() string {
 	return e.Message
 }
 
-func (e genericError) Code() uint8 {
+func (e genericError) Code() int {
 	return e.ExitCode
 }
 
 type codeError interface {
 	Error() string
-	Code() uint8
+	Code() int
 }
 
 // UsageError indicates that the user used the program incorrectly
 type UsageError struct {
-	ExitCode     uint8
+	ExitCode     int
 	Description  string
 	DebugMessage string
 }
@@ -52,7 +56,7 @@ func (u UsageError) Error() string {
 	return u.Description
 }
 
-func (u UsageError) Code() uint8 {
+func (u UsageError) Code() int {
 	return u.ExitCode
 }
 
@@ -85,7 +89,7 @@ func (v ValueError) Error() string {
 	return fmt.Sprintf("provided value %s was not valid (accepted values: %s)", v.Value, acceptable)
 }
 
-func (v ValueError) Code() uint8 {
+func (v ValueError) Code() int {
 	return ExitCodeValueError
 }
 
@@ -102,7 +106,7 @@ func (o OktaError) Error() string {
 	return o.Message
 }
 
-func (o OktaError) Code() uint8 {
+func (o OktaError) Code() int {
 	return ExitCodeUndisclosedOktaError
 }
 
@@ -116,9 +120,51 @@ func (o AWSError) Unwrap() error {
 }
 
 func (o AWSError) Error() string {
-	return o.Message
+	return fmt.Sprintf("%s: %s", o.Message, o.InnerError)
 }
 
-func (o AWSError) Code() uint8 {
+func (o AWSError) Code() int {
 	return ExitCodeAWSError
 }
+
+type TimeToLiveError struct {
+	MaxDuration       time.Duration
+	RequestedDuration time.Duration
+}
+
+func (o TimeToLiveError) Code() int {
+	return ExitCodeValueError
+}
+
+func (o TimeToLiveError) Error() string {
+	if o.MaxDuration == 0 && o.RequestedDuration == 0 {
+		// Duration is ambiguous/was not specified by AWS, so we return a generic message instead.
+		return "the TTL you requested exceeds the maximum TTL for this configuration"
+	}
+
+	// We cast to int to discard decimal places
+	return fmt.Sprintf("you requested a TTL of %d hours, but the maximum for this configuration is %d hours", int(o.RequestedDuration.Hours()), int(o.MaxDuration.Hours()))
+}
+
+// tryParseTimeToLiveError attempts to parse an error related to the DurationSeconds field in the STS request.
+//
+// If the given error does relate to the specified DurationSeconds being larger than MaxDurationSeconds, this function will return a more specific error than the one the AWS SDK provides, and returns true.
+// Returns nil and false in all other situations.
+func tryParseTimeToLiveError(err error) (error, bool) {
+	var awsErr awserr.Error
+	if errors.As(err, &awsErr) && awsErr.Code() == "ValidationError" {
+		var providedValue, maxValue time.Duration
+		// This is no more specific type than this, and yes, unfortunately the error message includes the count.
+		formatOne := "1 validation error detected: Value '%d' at 'durationSeconds' failed to satisfy constraint: Member must have value less than or equal to %d"
+		if n, parseErr := fmt.Sscanf(awsErr.Message(), formatOne, &providedValue, &maxValue); parseErr == nil && n == 2 {
+			return TimeToLiveError{MaxDuration: maxValue * time.Second, RequestedDuration: providedValue * time.Second}, true
+		}
+
+		formatAmbiguousMaximum := "The requested DurationSeconds exceeds the MaxSessionDuration set for this role."
+		if strings.Compare(awsErr.Message(), formatAmbiguousMaximum) == 0 {
+			return TimeToLiveError{MaxDuration: 0, RequestedDuration: 0}, true
+		}
+	}
+
+	return nil, false
+}

cli/error_test.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"testing"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws/awserr"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_tryParseTimeToLiveError(t *testing.T) {
+	t.Run("UnambiguousAmount", func(t *testing.T) {
+		validationError := awserr.New("ValidationError", "1 validation error detected: Value '86400' at 'durationSeconds' failed to satisfy constraint: Member must have value less than or equal to 43200", nil)
+		err, ok := tryParseTimeToLiveError(validationError)
+
+		require.True(t, ok)
+		require.NotNil(t, err)
+		require.Equal(t, err.Error(), "you requested a TTL of 24 hours, but the maximum for this configuration is 12 hours")
+		var ttlError TimeToLiveError
+		require.ErrorAs(t, err, &ttlError)
+		require.Equal(t, ttlError.MaxDuration, 43200*time.Second)
+		require.Equal(t, ttlError.RequestedDuration, 86400*time.Second)
+		require.Equal(t, ttlError.Code(), ExitCodeValueError)
+	})
+
+	t.Run("AmbiguousAmount", func(t *testing.T) {
+		validationError := awserr.New("ValidationError", "The requested DurationSeconds exceeds the MaxSessionDuration set for this role.", nil)
+		err, ok := tryParseTimeToLiveError(validationError)
+
+		require.True(t, ok)
+		require.NotNil(t, err)
+		require.Equal(t, err.Error(), "the TTL you requested exceeds the maximum TTL for this configuration")
+		var ttlError TimeToLiveError
+		require.ErrorAs(t, err, &ttlError)
+		require.Equal(t, ttlError.MaxDuration, time.Duration(0))
+		require.Equal(t, ttlError.RequestedDuration, time.Duration(0))
+		require.Equal(t, ttlError.Code(), ExitCodeValueError)
+	})
+}

cli/get.go

@@ -107,11 +107,6 @@ A role must be specified when using this command through the --role flag. You ma
 			return ValueError{Value: shellType, ValidValues: permittedShellTypes}
 		}
 
-		// make sure we enforce limit
-		if ttl > 8 {
-			ttl = 8
-		}
-
 		var accountID string
 		if len(args) > 0 {
 			accountID = args[0]
@@ -177,8 +172,15 @@ A role must be specified when using this command through the --role flag. You ma
 				SAMLAssertion:   &assertionStr,
 			})
 
+			if err, ok := tryParseTimeToLiveError(err); ok {
+				return err
+			}
+
 			if err != nil {
-				return AWSError{InnerError: err, Message: "failed to exchange credentials"}
+				return AWSError{
+					InnerError: err,
+					Message:    "failed to exchange credentials",
+				}
 			}
 
 			credentials = CloudCredentials{

cli/main.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/spf13/cobra"
 	"golang.org/x/exp/slog"
 )
 
@@ -28,10 +29,11 @@ func main() {
 	err := rootCmd.Execute()
 	var codeErr codeError
 	if errors.As(err, &codeErr) {
-		rootCmd.PrintErrf("keyconjurer: %s\n", codeErr.Error())
+		cobra.CheckErr(codeErr)
 		os.Exit(int(codeErr.Code()))
 	} else if err != nil {
-		rootCmd.PrintErrf("keyconjurer: %s\n", err.Error())
+		// Probably a cobra error.
+		cobra.CheckErr(err)
 		os.Exit(ExitCodeUnknownError)
 	}
 }

cli/root.go

@@ -102,4 +102,5 @@ To get started run the following commands:
 		return config.Write(file)
 	},
 	SilenceErrors: true,
+	SilenceUsage:  true,
 }

go.mod

@@ -4,6 +4,7 @@ require (
 	github.com/RobotsAndPencils/go-saml v0.0.0-20170520135329-fb13cb52a46b
 	github.com/aws/aws-lambda-go v1.19.1
 	github.com/aws/aws-sdk-go v1.34.19
+	github.com/aws/aws-sdk-go-v2/service/ec2 v1.148.2
 	github.com/coreos/go-oidc v2.2.1+incompatible
 	github.com/go-ini/ini v1.61.0
 	github.com/hashicorp/go-rootcerts v1.0.2
@@ -24,6 +25,7 @@ require (
 )
 
 require (
+	github.com/aws/smithy-go v1.20.1 // indirect
 	github.com/cenkalti/backoff/v4 v4.1.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect

go.sum

@@ -10,6 +10,11 @@ github.com/aws/aws-lambda-go v1.19.1/go.mod h1:jJmlefzPfGnckuHdXX7/80O3BvUUi12XO
 github.com/aws/aws-sdk-go v1.34.10/go.mod h1:5zCpMtNQVjRREroY7sYe8lOMRSxkhG6MZveU8YkpAk0=
 github.com/aws/aws-sdk-go v1.34.19 h1:x3MMvAJ1nfWviixEduchBSs65DgY5Y2pA2/NAcxVGOo=
 github.com/aws/aws-sdk-go v1.34.19/go.mod h1:5zCpMtNQVjRREroY7sYe8lOMRSxkhG6MZveU8YkpAk0=
+github.com/aws/aws-sdk-go-v2 v1.25.1 h1:P7hU6A5qEdmajGwvae/zDkOq+ULLC9tQBTwqqiwFGpI=
+github.com/aws/aws-sdk-go-v2/service/ec2 v1.148.2 h1:1oOlVyfM5Lzn/XKjqoVyy2i4OQhqOPaqYg3Jk+cZ4FE=
+github.com/aws/aws-sdk-go-v2/service/ec2 v1.148.2/go.mod h1:7MUTgVVnC1GAxx4SNQqzQalrm1n4v1HYa/R/LEB3CKo=
+github.com/aws/smithy-go v1.20.1 h1:4SZlSlMr36UEqC7XOyRVb27XMeZubNcBNN+9IgEPIQw=
+github.com/aws/smithy-go v1.20.1/go.mod h1:krry+ya/rV9RDcV/Q16kpu6ypI4K2czasz0NC3qS14E=
 github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kBD4zp0CCIs=
 github.com/cenkalti/backoff/v4 v4.1.0 h1:c8LkOFQTzuO0WBM/ae5HdGQuZPfPxp7lqBRwQRm4fSc=
 github.com/cenkalti/backoff/v4 v4.1.0/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=