electrum: fail to connect to a server w/ a self-signed certificate

[pythcoiner]

we actually fails to connect (in ssl) to an electrum server that have a self-signed certificate, in order to allow it we should have a look to few points:

• add an option to installer/settings to allow user to disable the certificate check, we should keep the default behaviour to check the certificate.
• certificate check should be disabled if we set electrum_client::Config validate_domain to false but not works as intended if electrum_client is used w/ default use-rusttls feauture. It works fine w/ use-openssl feature btw.
  ( i've opened an issue about this disrepancy in bdk repo)
• bdk_electrum crate does not offer use-openssl feature:

    Updating crates.io index
      Adding bdk_electrum v0.17.0 to dependencies
             Features:
             + use-rustls
             - use-rustls-ring

bdk_electrum Cargo.toml:

[dependencies]
bdk_core = { path = "../core", version = "0.1" }
electrum-client = { version = "0.21", features = [ "proxy" ], default-features = false }

[dev-dependencies]
bdk_testenv = { path = "../testenv", default-features = false }
bdk_chain = { path = "../chain", version = "0.18.0" }

[features]
default = ["use-rustls"]
use-rustls = ["electrum-client/use-rustls"]
use-rustls-ring = ["electrum-client/use-rustls-ring"]

[nondiremanuel]

As per what we were saying in the chat, we should be able to do it after the bump of BDK version (https://github.com/wizardsardine/liana-backend/pull/233).

Let's also remember to edit back the error message we are going to insert with #1342

[pythcoiner]

i'm really not sure upgrading bdk solve our issue, the issue seems related to rust-tls, and the bdk client does not reexport the ssl feature that seems the only actual way to make it work w/ self-signed certificate

[evanlinjin]

You don't need bdk_electrum to reexport features. You can just add another dependency to liana's Cargo.toml file.

electrum-client = { version = "0.21.0", features = ["use-openssl", "proxy"] }

[oleonardolima]

@pythcoiner I have a candidate fix in bitcoindevkit/rust-electrum-client#150 in case you'd like to take a look.

[pythcoiner]

i'll review it