42 lines
1.3 KiB
Go
42 lines
1.3 KiB
Go
// written by Daniel Oaks <daniel@danieloaks.net>
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// released under the ISC license
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package ircutils
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import "strings"
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var allowedHostnameChars = "abcdefghijklmnopqrstuvwxyz1234567890-."
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// HostnameIsValid provides a way for servers to check whether a looked-up client
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// hostname is valid (see InspIRCd #1033 for why this is required).
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//
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// This function shouldn't be called by clients since they don't need to validate
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// hostnames for IRC use, just by servers that need to confirm hostnames of incoming
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// clients.
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//
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// In addition to this function, servers should impose their own limits on max
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// hostname length -- this function limits it to 200 but most servers will probably
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// want to make it smaller than that.
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func HostnameIsValid(hostname string) bool {
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// IRC hostnames specifically require a period, rough limit of 200 chars
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if !strings.Contains(hostname, ".") || len(hostname) < 1 || len(hostname) > 200 {
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return false
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}
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// ensure each part of hostname is valid
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for _, part := range strings.Split(hostname, ".") {
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if len(part) < 1 || len(part) > 63 || strings.HasPrefix(part, "-") || strings.HasSuffix(part, "-") {
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return false
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}
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}
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// ensure all chars of hostname are valid
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for _, char := range strings.Split(strings.ToLower(hostname), "") {
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if !strings.Contains(allowedHostnameChars, char) {
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return false
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}
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}
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return true
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}
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