cmd/puppeth, vendor: update ssh, manage server keys (#14398)

vendor/golang.org/x/crypto/ssh/common.go

@@ -9,6 +9,7 @@ import (
 	"crypto/rand"
 	"fmt"
 	"io"
+	"math"
 	"sync"
 
 	_ "crypto/sha1"
@@ -40,7 +41,7 @@ var supportedKexAlgos = []string{
 	kexAlgoDH14SHA1, kexAlgoDH1SHA1,
 }
 
-// supportedKexAlgos specifies the supported host-key algorithms (i.e. methods
+// supportedHostKeyAlgos specifies the supported host-key algorithms (i.e. methods
 // of authenticating servers) in preference order.
 var supportedHostKeyAlgos = []string{
 	CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01,
@@ -186,7 +187,7 @@ type Config struct {
 
 	// The maximum number of bytes sent or received after which a
 	// new key is negotiated. It must be at least 256. If
-	// unspecified, 1 gigabyte is used.
+	// unspecified, a size suitable for the chosen cipher is used.
 	RekeyThreshold uint64
 
 	// The allowed key exchanges algorithms. If unspecified then a
@@ -230,11 +231,12 @@ func (c *Config) SetDefaults() {
 	}
 
 	if c.RekeyThreshold == 0 {
-		// RFC 4253, section 9 suggests rekeying after 1G.
-		c.RekeyThreshold = 1 << 30
-	}
-	if c.RekeyThreshold < minRekeyThreshold {
+		// cipher specific default
+	} else if c.RekeyThreshold < minRekeyThreshold {
 		c.RekeyThreshold = minRekeyThreshold
+	} else if c.RekeyThreshold >= math.MaxInt64 {
+		// Avoid weirdness if somebody uses -1 as a threshold.
+		c.RekeyThreshold = math.MaxInt64
 	}
 }