fix: Trims SQN string passed to strictHex to make sure it doesn't have any non-printable characters #163
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… non-printable characters Signed-off-by: Bartlomiej Gmerek <[email protected]>
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The
strictHexmethod is used to normalize SQN hex - it needs to be exactly 12-characters long in order to produce a 6-element byte slice.In some cases, the SQN hex returned by the UDR client contains a new line at the end of the valid SQN hex string. As a result,
strictHexassumes that the string length is 13 characters and "normalizes" it by cutting of the first digit. This produces an invalid, 11-char long output, which causes authentication error:err encoding/hex: invalid byte: U+000A.This PR addresses this problem by trimming all non-printable chars off the input string before
strictHexassesses the length of the input.Some logs:
Initial state, sequenceNumber assigned to the subscriber is
0001863958fe, UE authenticates for the first time:Authentication was successful, the SQN has been increased. So far, so good.
Now the gNB fails (CU and DU are restarted) and the UE needs to reattach:
UDM fetches the SQN hex from UDR:
0001863958ff, but because it's returned with a new line at the end,strictHexthinks it's 13-chars long. So it cuts one character and returns001863958ff. New line gets trimmed as well, becausestrictHexcreates a slice. New SQN hex is 11-chars long, so it can't produce a 6-element byte slice. As a result we geterr encoding/hex: invalid byte: U+000A.After applying a fix from this PR we get: