feature: support flexible checksums

[Velfi]

Motivation and Context

#1482

Description

This PR adds all the inlineables and codegen necessary to support flexible checksums. It also updates the S3 model to the latest version and tests the new checksum functionality against that model.

Testing

I have written many tests to ensure the code is correct.

Checklist

• I have updated CHANGELOG.next.toml if I made changes to the smithy-rs codegen or runtime crates
• I have updated CHANGELOG.next.toml if I made changes to the AWS SDK, generated SDK code, or SDK runtime crates

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[jdisanti]

Exciting to see all this come together! It looks like there's a server codegen compile error that's preventing CI from running.

[jdisanti]

Seems like we should create the algorithm once to avoid an unnecessary allocation since it returns a boxed value. It's being created up here for validation, and then again below for the actual checksum calculation.

Edit: I see the reason for this now in the code comment below. I think we should create an intermediate Algorithm enum type that is easily converted to/from algorithm names and header names, and can easily create algorithm implementations. I prototyped this a bit and made it a macro so that there's no risk of any of the functions on the enum getting out of sync with each other:

macro_rules! associate_algorithms {
    (pub enum $enum_name:ident { $($algorithm_ident:ident => { name: $algorithm_name:ident, header_name: $header_name:ident },)+ }) => {
        #[derive(Copy, Clone)]
        pub enum $enum_name {
            $($algorithm_ident,)+
        }

        impl $enum_name {
            pub fn to_header_name(&self) -> Result<HeaderName, Box<dyn std::error::Error>> {
                match self {
                    $(Self::$algorithm_ident => Ok($header_name.clone()),)+
                }
            }

            pub fn from_header_name(checksum_header_name: &HeaderName) -> Result<Self, Box<dyn std::error::Error>> {
                $(if checksum_header_name == $header_name { return Ok(Self::$algorithm_ident) })+
                Err(Box::new(Error::UnknownChecksumHeaderName(
                    checksum_header_name.to_owned(),
                )))
            }

            pub fn to_algorithm_name(&self) -> &str {
                match self {
                    $(Self::$algorithm_ident => $algorithm_name,)+
                }
            }

            pub fn from_algorithm_name(algorithm_name: &str) -> Result<Self, Box<dyn std::error::Error>> {
                $(if algorithm_name == $algorithm_name { return Ok(Self::$algorithm_ident) })+
                Err(Box::new(Error::UnknownChecksumAlgorithm(
                    algorithm_name.to_owned(),
                )))
            }

            pub fn to_impl(&self) -> Box<dyn HttpChecksum> {
                match self {
                    $(Self::$algorithm_ident => Box::new($algorithm_ident::default()),)+
                }
            }
        }
    };
}

associate_algorithms!(
    pub enum Algorithm {
        Crc32 => { name: CRC_32_NAME, header_name: CRC_32_HEADER_NAME },
        Crc32c => { name: CRC_32_C_NAME, header_name: CRC_32_C_HEADER_NAME },
        Md5 => { name: MD5_NAME, header_name: MD5_HEADER_NAME },
        Sha1 => { name: SHA_1_NAME, header_name: SHA_1_HEADER_NAME },
        Sha256 => { name: SHA_256_NAME, header_name: SHA_256_HEADER_NAME },
    }
);

Then we can verify an algorithm is supported with:

let algorithm = Algorithm::from_algorithm_name(&checksum_algorithm)
    .map_err(|err| BuildError::Other(err))?;

This Algorithm enum is Copy, so we don't have to worry about it moving anywhere. Then inside the body checksumming, we easily get a fresh implementation when we need it:

let checksum = algorithm.to_impl();

No error checking required since we already error checked.

[Velfi]

I implemented the enum idea, but not the macro. Let me know what you think.

[rcoh]

LGTM! just some small stylistic changes

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

A new doc preview is ready to view.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

A new doc preview is ready to view.

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

A new doc preview is ready to view.

[crisidev]

LGTM from a server perspective. The diff is also empty, which is a good indicator!

[github-actions]

A new generated diff is ready to view.

• AWS SDK (ignoring whitespace)
• No codegen difference in the Server Test
• No codegen difference in the Server Test Python

A new doc preview is ready to view.