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cmd/tailscale: simplify hostname validation

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Signed-off-by: Dmytro Shynkevych <dmytro@tailscale.com>
This commit is contained in:
Dmytro Shynkevych 2020-07-15 18:05:08 -04:00 committed by Brad Fitzpatrick
parent 65d2537c05
commit 852136a03c
1 changed files with 2 additions and 33 deletions
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35
cmd/tailscale/cli/up.go
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@ -80,37 +80,6 @@
hostname string
}
// validateHostname checks that name is a valid domain name label
// pursuant to https://tools.ietf.org/html/rfc1034#section-3.1.
func validateHostname(name string) error {
switch {
// Empty string is treated as missing hostname and replaced downstream.
case len(name) == 0:
return nil
case len(name) > 63:
return fmt.Errorf("longer than 63 characters")
}
name = strings.ToLower(name)
first, last := name[0], name[len(name)-1]
// This is more obviously correct than using package unicode,
// though that can work too if we ensure that characters are below MaxASCII.
if !('a' <= first && first <= 'z') {
return fmt.Errorf("does not start with a letter")
}
if !(('a' <= last && last <= 'z') || ('0' <= last && last <= '9')) {
return fmt.Errorf("does not end with a letter or digit")
}
for i, c := range name {
if !(('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || (c == '-')) {
return fmt.Errorf("[%d] = %c is not a letter, digit or hyphen", i, c)
}
}
return nil
}
// parseIPOrCIDR parses an IP address or a CIDR prefix. If the input
// is an IP address, it is returned in CIDR form with a /32 mask for
// IPv4 or a /128 mask for IPv6.
@ -199,8 +168,8 @@ func runUp(ctx context.Context, args []string) error {
}
}
if err := validateHostname(upArgs.hostname); err != nil {
log.Fatalf("illegal hostname: %v", err)
if len(upArgs.hostname) > 256 {
log.Fatalf("hostname too long: %d bytes (max 256)", len(upArgs.hostname))
}
// TODO(apenwarr): fix different semantics between prefs and uflags