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Implement httpLabel with nom #996

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merged 2 commits into from
Jan 5, 2022
Merged

Implement httpLabel with nom #996

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29cbd04
Implement httpLabel with nom
82marbag Jan 4, 2022
bee5b11
Merge branch 'main' into main
david-perez Jan 5, 2022
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1 change: 1 addition & 0 deletions ...rc/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/ServerCargoDependency.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ object ServerCargoDependency {
val AsyncTrait: CargoDependency = CargoDependency("async-trait", CratesIo("0.1"))
val AxumCore: CargoDependency = CargoDependency("axum-core", CratesIo("0.1"))
val FuturesUtil: CargoDependency = CargoDependency("futures-util", CratesIo("0.3"))
val Nom: CargoDependency = CargoDependency("nom", CratesIo("7"))
val PinProjectLite: CargoDependency = CargoDependency("pin-project-lite", CratesIo("0.2"))
val SerdeUrlEncoded: CargoDependency = CargoDependency("serde_urlencoded", CratesIo("0.7"))
val Tower: CargoDependency = CargoDependency("tower", CratesIo("0.4"))
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93 changes: 64 additions & 29 deletions ...oftware/amazon/smithy/rust/codegen/server/smithy/protocols/ServerHttpProtocolGenerator.kt
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Expand Up @@ -107,6 +107,7 @@ private class ServerHttpProtocolImplGenerator(
"HttpBody" to CargoDependency.HttpBody.asType(),
"Hyper" to CargoDependency.Hyper.asType(),
"LazyStatic" to CargoDependency.LazyStatic.asType(),
"Nom" to ServerCargoDependency.Nom.asType(),
"PercentEncoding" to CargoDependency.PercentEncoding.asType(),
"Regex" to CargoDependency.Regex.asType(),
"SerdeUrlEncoded" to ServerCargoDependency.SerdeUrlEncoded.asType(),
Expand Down Expand Up @@ -572,46 +573,80 @@ private class ServerHttpProtocolImplGenerator(
if (pathBindings.isEmpty()) {
return
}
val pattern = StringBuilder()
val httpTrait = httpBindingResolver.httpTrait(operationShape)
httpTrait.uri.segments.forEach {
pattern.append("/")
if (it.isLabel) {
pattern.append("(?P<${it.content}>")
if (it.isGreedyLabel) {
pattern.append(".+")
val greedyLabelIndex = httpTrait.uri.segments.indexOfFirst { it.isGreedyLabel }
val segments =
if (greedyLabelIndex >= 0)
httpTrait.uri.segments.slice(0 until (greedyLabelIndex + 1))
else
httpTrait.uri.segments
val restAfterGreedyLabel =
if (greedyLabelIndex >= 0)
httpTrait.uri.segments.slice((greedyLabelIndex + 1) until httpTrait.uri.segments.size).joinToString(prefix = "/", separator = "/")
else
""
val labeledNames = segments
.mapIndexed { index, segment ->
if (segment.isLabel) { "m$index" } else { "_" }
}
.joinToString(prefix = (if (segments.size > 1) "(" else ""), separator = ",", postfix = (if (segments.size > 1) ")" else ""))
val nomParser = segments
.map { segment ->
if (segment.isGreedyLabel) {
"#{Nom}::combinator::rest::<_, #{Nom}::error::Error<&str>>"
} else if (segment.isLabel) {
"""#{Nom}::branch::alt::<_, _, #{Nom}::error::Error<&str>, _>((#{Nom}::bytes::complete::take_until("/"), #{Nom}::combinator::rest))"""
} else {
pattern.append("[^/]+")
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Why were we accepting empty path segments? I see the TypeScript sSDK is also stripping away empty path segments.

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Writing my thoughts down here. I guess done this way because anecdotally servers accept empty path segments e.g. https://github.com//awslabs///////smithy-typescript///commits works fine.

But when extracting labels, I'm not sure about whether this behavior should be the correct one, and I don't see it specified in the Smithy spec. I'm thinking of possible ambiguous scenarios e.g. say the URI pattern is /foo/{label}/bar and the server receives a request with URI path /foo//bar. Should the label field be bound to an empty string? Or should we strip away the empty segment and reject the request?

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My opinion on this and interpretation of the Smithy spec is that we were indeed doing it wrong and empty path segments should not be stripped away, but I've opened an issue with the Smithy team to clarify the spec: smithy-lang/smithy#1024

"""#{Nom}::bytes::complete::tag::<_, _, #{Nom}::error::Error<&str>>("${segment.content}")"""
}
pattern.append(")")
} else {
pattern.append(it.content)
}
}
.joinToString(
// TODO: tuple() is currently limited to 21 items
prefix = if (segments.size > 1) "#{Nom}::sequence::tuple::<_, _, #{Nom}::error::Error<&str>, _>((" else "",
postfix = if (segments.size > 1) "))" else "",
transform = { parser ->
"""
#{Nom}::sequence::preceded(#{Nom}::bytes::complete::tag("/"), $parser)
""".trimIndent()
}
)
with(writer) {
rustTemplate("let input_string = request.uri().path();")
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if (greedyLabelIndex >= 0 && greedyLabelIndex + 1 < httpTrait.uri.segments.size) {
rustTemplate(
"""
if !input_string.ends_with(${restAfterGreedyLabel.dq()}) {
return std::result::Result::Err(#{SmithyRejection}::Deserialize(
aws_smithy_http_server::rejection::Deserialize::from_err(format!("Postfix not found: {}", ${restAfterGreedyLabel.dq()}))));
}
let input_string = &input_string[..(input_string.len() - ${restAfterGreedyLabel.dq()}.len())];
""".trimIndent(),
*codegenScope
)
}
rustTemplate(
"""
#{LazyStatic}::lazy_static! {
static ref RE: #{Regex}::Regex = #{Regex}::Regex::new("$pattern").unwrap();
}
let (input_string, $labeledNames) = $nomParser(input_string)?;
debug_assert_eq!("", input_string);
""".trimIndent(),
*codegenScope,
*codegenScope
)
rustBlock("if let Some(captures) = RE.captures(request.uri().path())") {
pathBindings.forEach {
val deserializer = generateParsePercentEncodedStrFn(it)
rustTemplate(
"""
if let Some(m) = captures.name("${it.locationName}") {
input = input.${it.member.setterName()}(
#{deserializer}(m.as_str())?
segments
.forEachIndexed { index, segment ->
val binding = pathBindings.find { it.memberName == segment.content }
if (binding != null && segment.isLabel) {
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If segment.isLabel is true, then binding must be non-null, right? Because pathBindings contains all the @httpLabel bindings.

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In some cases, such as /foo/{foo}, foo is found as binding too because I look for the name

val deserializer = generateParsePercentEncodedStrFn(binding)
rustTemplate(
"""
input = input.${binding.member.setterName()}(
#{deserializer}(m$index)?
);
}
""".trimIndent(),
"deserializer" to deserializer,
)
""".trimIndent(),
*codegenScope,
"deserializer" to deserializer,
)
}
}
}
}
}

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1 change: 1 addition & 0 deletions rust-runtime/aws-smithy-http-server/Cargo.toml
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Expand Up @@ -28,6 +28,7 @@ http = "0.2"
http-body = "0.4"
hyper = { version = "0.14", features = ["server", "http1", "http2", "tcp"] }
mime = "0.3"
nom = "7"
pin-project-lite = "0.2"
regex = "1.0"
serde_urlencoded = "0.7"
Expand Down
6 changes: 6 additions & 0 deletions rust-runtime/aws-smithy-http-server/src/rejection.rs
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Expand Up @@ -227,3 +227,9 @@ impl From<serde_urlencoded::de::Error> for SmithyRejection {
SmithyRejection::Deserialize(Deserialize::from_err(err))
}
}

impl From<nom::Err<nom::error::Error<&str>>> for SmithyRejection {
fn from(err: nom::Err<nom::error::Error<&str>>) -> Self {
SmithyRejection::Deserialize(Deserialize::from_err(err.to_owned()))
}
}