jordi fita mas
835e52dbcb
Since most of PL/pgSQL functions accept a `uuid` domain, we get an error
if the value is not valid, forcing us to return an HTTP 500, as we
can not detect that the error was due to that.
Instead, i now validate that the slug is indeed a valid UUID before
attempting to send it to the database, returning the correct HTTP error
code and avoiding useless calls to the database.
I based the validation function of Parse() from Google’s uuid package[0]
because this function is an order or magnitude faster in benchmarks:
goos: linux
goarch: amd64
pkg: dev.tandem.ws/tandem/numerus/pkg
cpu: Intel(R) Core(TM) i5-6200U CPU @ 2.30GHz
BenchmarkValidUuid-4 36946050 29.37 ns/op
BenchmarkValidUuid_Re-4 3633169 306.70 ns/op
The regular expression used for the benchmark was:
var re = regexp.MustCompile("^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[8|9|aA|bB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$")
And the input parameter for both functions was the following valid UUID,
because most of the time the passed UUID will be valid:
"f47ac10b-58cc-0372-8567-0e02b2c3d479"
I did not use the uuid package, even though it is in Debian’s
repository, because i only need to check whether the value is valid,
not convert it to a byte array. As far as i know, that package can not
do that.
[0]: https://github.com/google/uuid
47 lines
1.8 KiB
Go
47 lines
1.8 KiB
Go
package pkg
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func ValidUuid(s string) bool {
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if len(s) != 36 {
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return false
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}
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// it must be of the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
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if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
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return false
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}
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for _, x := range [16]int{
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0, 2, 4, 6,
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9, 11,
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14, 16,
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19, 21,
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24, 26, 28, 30, 32, 34} {
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if !validHex(s[x], s[x+1]) {
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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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// xvalues returns the value of a byte as a hexadecimal digit or 255.
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var xvalues = [256]byte{
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
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255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
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}
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func validHex(x1, x2 byte) bool {
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return xvalues[x1] != 255 && xvalues[x2] != 255
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}
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