# `WebSockAdapter.UpgradeValidation`
[🔗](https://github.com/phoenixframework/websock_adapter/blob/main/lib/websock_adapter/upgrade_validation.ex#L1)

Provides validation of WebSocket upgrade requests as described in RFC6455§4.2 & RFC8441§5

The `validate_upgrade/1` function is called internally by `WebSockAdapter.upgrade/4`; there is
no need to call it yourself before attempting an upgrade (though doing so is harmless)

# `validate_upgrade`

```elixir
@spec validate_upgrade(Plug.Conn.t()) :: :ok | {:error, String.t()}
```

Validates that the request satisfies the requirements to issue a WebSocket upgrade response.

Validations are performed based on the clauses laid out in RFC6455§4.2 & RFC8441§5

This function does not actually perform an upgrade or change the connection in any way.
Regardless of whether or not this function indicates a satisfactory connection, the
underlying web server MAY still choose to not perform the upgrade (this scenario likely
indicates a discrepancy between the validations done here and those done in the underlying web
server & would merit further investigation)

Returns `:ok` if the connection satisfies the requirements for a WebSocket upgrade, and
`{:error, reason}` if not

# `validate_upgrade!`

```elixir
@spec validate_upgrade!(Plug.Conn.t()) :: :ok
```

Raising variant of `validate_upgrade/1`.

Returns `:ok` if the connection satisfies the requirements for a WebSocket upgrade, and raises
a `WebSockAdapter.UpgradeError` error if validation fails.

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*Consult [api-reference.md](api-reference.md) for complete listing*