implement endpoint to list files in a directory

Cargo.lock

@@ -39,6 +39,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6d6fd624c75e18b3b4c6b9caf42b1afe24437daaee904069137d8bab077be8b8"
 dependencies = [
  "axum-core",
+ "axum-macros",
  "bytes",
  "form_urlencoded",
  "futures-util",
@@ -51,6 +52,7 @@ dependencies = [
  "matchit",
  "memchr",
  "mime",
+ "multer",
  "percent-encoding",
  "pin-project-lite",
  "rustversion",
@@ -86,6 +88,17 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "axum-macros"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "604fde5e028fea851ce1d8570bbdc034bec850d157f7569d10f347d06808c05c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "backtrace"
 version = "0.3.74"
@@ -125,8 +138,15 @@ version = "0.1.0"
 dependencies = [
  "axum",
  "figment",
+ "futures",
+ "futures-util",
+ "problem_details",
  "serde",
  "tokio",
+ "tokio-stream",
+ "tracing",
+ "tracing-log",
+ "tracing-subscriber",
 ]
 
 [[package]]
@@ -135,6 +155,15 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "encoding_rs"
+version = "0.8.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75030f3c4f45dafd7586dd6780965a8c7e8e285a5ecb86713e63a79c5b2766f3"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.1"
@@ -148,6 +177,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8cb01cd46b0cf372153850f4c6c272d9cbea2da513e07538405148f95bd789f3"
 dependencies = [
  "atomic",
+ "pear",
  "serde",
  "toml",
  "uncased",
@@ -169,6 +199,21 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "futures"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "65bc07b1a8bc7c85c5f2e110c476c7389b4554ba72af57d8445ea63a576b0876"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-executor",
+ "futures-io",
+ "futures-sink",
+ "futures-task",
+ "futures-util",
+]
+
 [[package]]
 name = "futures-channel"
 version = "0.3.31"
@@ -176,6 +221,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dff15bf788c671c1934e366d07e30c1814a8ef514e1af724a602e8a2fbe1b10"
 dependencies = [
  "futures-core",
+ "futures-sink",
 ]
 
 [[package]]
@@ -184,6 +230,40 @@ version = "0.3.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "05f29059c0c2090612e8d742178b0580d2dc940c837851ad723096f87af6663e"
 
+[[package]]
+name = "futures-executor"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e28d1d997f585e54aebc3f97d39e72338912123a67330d723fdbb564d646c9f"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "futures-util",
+]
+
+[[package]]
+name = "futures-io"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9e5c1b78ca4aae1ac06c48a526a655760685149f0d465d21f37abfe57ce075c6"
+
+[[package]]
+name = "futures-macro"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "162ee34ebcb7c64a8abebc059ce0fee27c2262618d7b60ed8faf72fef13c3650"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "futures-sink"
+version = "0.3.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e575fab7d1e0dcb8d0c7bcf9a63ee213816ab51902e6d244a95819acacf1d4f7"
+
 [[package]]
 name = "futures-task"
 version = "0.3.31"
@@ -196,10 +276,16 @@ version = "0.3.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9fa08315bb612088cc391249efdc3bc77536f16c91f6cf495e6fbe85b20a4a81"
 dependencies = [
+ "futures-channel",
  "futures-core",
+ "futures-io",
+ "futures-macro",
+ "futures-sink",
  "futures-task",
+ "memchr",
  "pin-project-lite",
  "pin-utils",
+ "slab",
 ]
 
 [[package]]
@@ -248,6 +334,16 @@ dependencies = [
  "pin-project-lite",
 ]
 
+[[package]]
+name = "http-serde"
+version = "2.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0f056c8559e3757392c8d091e796416e4649d8e49e88b8d76df6c002f05027fd"
+dependencies = [
+ "http",
+ "serde",
+]
+
 [[package]]
 name = "httparse"
 version = "1.9.5"
@@ -305,12 +401,24 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inlinable_string"
+version = "0.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c8fae54786f62fb2918dcfae3d568594e50eb9b5c25bf04371af6fe7516452fb"
+
 [[package]]
 name = "itoa"
 version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d75a2a4b1b190afb6f5425f10f6a8f959d2ea0b9c2b1d79553551850539e4674"
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
 [[package]]
 name = "libc"
 version = "0.2.169"
@@ -371,6 +479,33 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "multer"
+version = "3.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83e87776546dc87511aa5ee218730c92b666d7264ab6ed41f9d215af9cd5224b"
+dependencies = [
+ "bytes",
+ "encoding_rs",
+ "futures-util",
+ "http",
+ "httparse",
+ "memchr",
+ "mime",
+ "spin",
+ "version_check",
+]
+
+[[package]]
+name = "nu-ansi-term"
+version = "0.46.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a8165726e8236064dbb45459242600304b42a5ea24ee2948e18e023bf7ba84"
+dependencies = [
+ "overload",
+ "winapi",
+]
+
 [[package]]
 name = "object"
 version = "0.36.7"
@@ -386,6 +521,12 @@ version = "1.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
 [[package]]
 name = "parking_lot"
 version = "0.12.3"
@@ -409,6 +550,29 @@ dependencies = [
  "windows-targets",
 ]
 
+[[package]]
+name = "pear"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "61a386cd715229d399604b50d1361683fe687066f42d56f54be995bc6868f71c"
+dependencies = [
+ "inlinable_string",
+ "pear_codegen",
+ "yansi",
+]
+
+[[package]]
+name = "pear_codegen"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da9f0f13dac8069c139e8300a6510e3f4143ecf5259c60b116a9b271b4ca0d54"
+dependencies = [
+ "proc-macro2",
+ "proc-macro2-diagnostics",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "percent-encoding"
 version = "2.3.1"
@@ -427,6 +591,19 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
+[[package]]
+name = "problem_details"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ee2055bf7d8f34bd11bf85388b878bf244256015f1ed290b6b717c0e97bb478"
+dependencies = [
+ "axum",
+ "http",
+ "http-serde",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.92"
@@ -436,6 +613,19 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "proc-macro2-diagnostics"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af066a9c399a26e020ada66a034357a868728e72cd426f3adcd35f80d88d88c8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "version_check",
+ "yansi",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.38"
@@ -541,6 +731,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "sharded-slab"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f40ca3c46823713e0d4209592e8d6e826aa57e928f09752619fc696c499637f6"
+dependencies = [
+ "lazy_static",
+]
+
 [[package]]
 name = "signal-hook-registry"
 version = "1.4.2"
@@ -550,6 +749,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "slab"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f92a496fb766b417c996b9c5e57daf2f7ad3b0bebe1ccfca4856390e3d3bb67"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "smallvec"
 version = "1.13.2"
@@ -566,6 +774,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "spin"
+version = "0.9.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+
 [[package]]
 name = "syn"
 version = "2.0.95"
@@ -583,6 +797,16 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0bf256ce5efdfa370213c1dabab5935a12e49f2c58d15e9eac2870d3b4f27263"
 
+[[package]]
+name = "thread_local"
+version = "1.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b9ef9bad013ada3808854ceac7b46812a6465ba368859a37e2100283d2d719c"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+]
+
 [[package]]
 name = "tokio"
 version = "1.42.0"
@@ -612,6 +836,17 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tokio-stream"
+version = "0.1.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eca58d7bba4a75707817a2c44174253f9236b2d5fbd055602e9d5c07c139a047"
+dependencies = [
+ "futures-core",
+ "pin-project-lite",
+ "tokio",
+]
+
 [[package]]
 name = "toml"
 version = "0.8.19"
@@ -682,9 +917,21 @@ checksum = "784e0ac535deb450455cbfa28a6f0df145ea1bb7ae51b821cf5e7927fdcfbdd0"
 dependencies = [
  "log",
  "pin-project-lite",
+ "tracing-attributes",
  "tracing-core",
 ]
 
+[[package]]
+name = "tracing-attributes"
+version = "0.1.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "395ae124c09f9e6918a2310af6038fba074bcf474ac352496d5910dd59a2226d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "tracing-core"
 version = "0.1.33"
@@ -692,6 +939,32 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e672c95779cf947c5311f83787af4fa8fffd12fb27e4993211a84bdfd9610f9c"
 dependencies = [
  "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee855f1f400bd0e5c02d150ae5de3840039a3f54b025156404e34c23c03f47c3"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e8189decb5ac0fa7bc8b96b7cb9b2701d60d48805aca84a238004d665fcc4008"
+dependencies = [
+ "nu-ansi-term",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing-core",
+ "tracing-log",
 ]
 
 [[package]]
@@ -709,6 +982,12 @@ version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83"
 
+[[package]]
+name = "valuable"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "830b7e5d4d90034032940e4ace0d9a9a057e7a45cd94e6c007832e39edb82f6d"
+
 [[package]]
 name = "version_check"
 version = "0.9.5"
@@ -721,6 +1000,28 @@ version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
@@ -802,3 +1103,9 @@ checksum = "39281189af81c07ec09db316b302a3e67bf9bd7cbf6c820b50e35fee9c2fa980"
 dependencies = [
  "memchr",
 ]
+
+[[package]]
+name = "yansi"
+version = "1.0.0-rc"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ee746ad3851dd3bc40e4a028ab3b00b99278d929e48957bcb2d111874a7e43e"

application.toml

@@ -1,2 +0,0 @@
-port = 3000
-listen = "0.0.0.0"

casket-backend/Cargo.toml

@@ -2,9 +2,18 @@
 name = "casket-backend"
 version = "0.1.0"
 edition = "2021"
+description = "Backend for the casket file cloud."
+repository = "https://git.nifni.eu/nif/casket"
 
 [dependencies]
-axum = { version = "0.8.1" }
+axum = { version = "0.8.1", features = ["multipart", "macros"] }
 tokio = { version = "1.42.0", features = ["full"] }
-figment = { version = "0.10.19", features = ["toml"] }
+tokio-stream = "0.1.17"
-serde = {version = "1.0.217", features = ["derive"]}
+futures = "0.3"
+futures-util = "0.3"
+figment = { version = "0.10.19", features = ["toml", "env"] }
+serde = { version = "1.0.217", features = ["derive"] }
+tracing = "0.1.41"
+tracing-log = "0.2.0"
+tracing-subscriber = "0.3.19"
+problem_details = { version = "0.7.0", features = ["axum"] }

casket-backend/README.md

@@ -0,0 +1,25 @@
+# Casket backend
+
+Backend server for casket.
+
+## Running
+
+```bash
+cd casket-backend
+cargo run
+```
+
+## Configuration
+
+See [casket.toml](./casket.toml) for an example config file. By default, the following files are checked
+to exist:
+
+- `./casket-backend/casket.toml`
+- `/config/casket.toml`
+
+Additionally, it is possible to provide configs via environment variables. Use the prefix `CASKET_`.
+For nested configs use two underscores to mark the place to split:
+
+```bash
+CASKET_SERVER__port=1234
+```

casket-backend/casket.toml

@@ -0,0 +1,6 @@
+[server]
+port = 3000
+bind_address = "127.0.0.1"
+
+[files]
+directory = "/tmp/casket"

casket-backend/src/config.rs

@@ -1,15 +1,32 @@
+use figment::providers::{Env, Format};
 use figment::{providers::Toml, Figment};
-use figment::providers::Format;
 use serde::Deserialize;
+use std::path::PathBuf;
+
+pub const CONFIG_LOCATIONS: [&str; 2] = ["casket-backend/casket.toml", "/config/casket.toml"];
 
 #[derive(Deserialize, Clone, Debug)]
 pub struct Config {
-    port: u16,
+    pub server: Server,
-    listen: String,
+    pub files: Files,
+}
+
+#[derive(Deserialize, Clone, Debug)]
+pub struct Server {
+    pub port: u16,
+    pub bind_address: String,
+}
+#[derive(Deserialize, Clone, Debug)]
+pub struct Files {
+    pub directory: PathBuf,
 }
 
 pub fn get_config() -> figment::Result<Config> {
-    Figment::new()
+    CONFIG_LOCATIONS
-        .merge(Toml::file("application.toml"))
+        .iter()
+        .fold(Figment::new(), |figment, location| {
+            figment.merge(Toml::file(location))
+        })
+        .join(Env::prefixed("CASKET_").split("__"))
         .extract()
 }

casket-backend/src/errors.rs

@@ -0,0 +1,17 @@
+use axum::http::StatusCode;
+use problem_details::ProblemDetails;
+use std::fmt::Debug;
+use tracing::error;
+
+pub const ERROR_DETAILS_PATH_TRAVERSAL: &str = "You must not traverse!";
+pub const ERROR_DETAILS_INTERNAL_ERROR: &str =
+    "Internal Error! Check the logs of the backend service for details.";
+pub const ERROR_DETAILS_ABSOLUTE_PATH_NOT_ALLOWED: &str = "Absolute paths are not allowed.";
+pub const ERROR_DETAILS_NO_NAME_PROVIDED_MULTIPART_FIELD: &str =
+    "No name provided for multipart form field";
+
+pub fn to_internal_error(error: impl Debug) -> ProblemDetails {
+    error!("{:?}", error);
+    ProblemDetails::from_status_code(StatusCode::INTERNAL_SERVER_ERROR)
+        .with_detail(ERROR_DETAILS_INTERNAL_ERROR)
+}

casket-backend/src/extractor_helper.rs

@@ -0,0 +1,24 @@
+use axum::extract::FromRequestParts;
+use axum::http::request::Parts;
+use axum::http::StatusCode;
+use problem_details::ProblemDetails;
+use std::fmt::Debug;
+
+pub struct WithProblemDetails<T>(pub T);
+
+impl<T, S> FromRequestParts<S> for WithProblemDetails<T>
+where
+    T: FromRequestParts<S>,
+    T::Rejection: Debug,
+    S: Sync,
+{
+    type Rejection = ProblemDetails;
+
+    async fn from_request_parts(parts: &mut Parts, state: &S) -> Result<Self, Self::Rejection> {
+        match T::from_request_parts(parts, state).await {
+            Ok(inner) => Ok(Self(inner)),
+            Err(rejection) => Err(ProblemDetails::from_status_code(StatusCode::BAD_REQUEST)
+                .with_detail(format!("{rejection:?}"))),
+        }
+    }
+}

casket-backend/src/files/list.rs

@@ -0,0 +1,107 @@
+use crate::errors::to_internal_error;
+use crate::extractor_helper::WithProblemDetails;
+use crate::files::build_system_path;
+use crate::{errors, AppState};
+use axum::extract::{Query, State};
+use axum::http::StatusCode;
+use axum::{debug_handler, Json};
+use problem_details::ProblemDetails;
+use serde::{Deserialize, Serialize};
+use std::io::Error;
+use std::path::PathBuf;
+use tokio::fs::{read_dir, DirEntry};
+use tracing::{debug, error};
+
+#[debug_handler]
+pub async fn query_file_tree(
+    State(state): State<AppState>,
+    axum::extract::Path(user_id): axum::extract::Path<String>,
+    WithProblemDetails(Query(query)): WithProblemDetails<Query<FileQuery>>,
+) -> Result<Json<PathElements>, ProblemDetails> {
+    let path = build_system_path(&state.config.files.directory, &user_id, &query.path)?;
+    debug!("Loading path: {:?}", path);
+    Ok(PathElements::new(load_directory(path, query.nesting).await?).into())
+}
+
+async fn load_directory(path: PathBuf, nesting: u32) -> Result<Vec<PathElement>, ProblemDetails> {
+    match read_dir(path).await {
+        Err(error) => Err(map_io_error(error)),
+        Ok(mut value) => {
+            let mut result = vec![];
+            while let Some(next) = value.next_entry().await.map_err(map_io_error)? {
+                result.push(PathElement::from(next, nesting).await?);
+            }
+            Ok(result)
+        }
+    }
+}
+
+fn map_io_error(error: Error) -> ProblemDetails {
+    match error.kind() {
+        std::io::ErrorKind::NotFound => ProblemDetails::from_status_code(StatusCode::NOT_FOUND),
+        _ => to_internal_error(error),
+    }
+}
+
+#[derive(Deserialize)]
+pub struct FileQuery {
+    path: PathBuf,
+    #[serde(default = "u32::min_value")]
+    nesting: u32,
+}
+
+#[derive(Serialize)]
+pub struct PathElements {
+    files: Vec<PathElement>,
+}
+
+impl PathElements {
+    pub fn new(files: Vec<PathElement>) -> Self {
+        Self { files }
+    }
+}
+
+#[derive(Serialize)]
+pub struct PathElement {
+    name: String,
+    is_dir: bool,
+    children: Option<Vec<PathElement>>,
+}
+
+impl PathElement {
+    async fn from(value: DirEntry, nesting: u32) -> Result<Self, ProblemDetails> {
+        let metadata = value.metadata().await.unwrap();
+        debug!("File type: {:?}", value.file_type().await.unwrap());
+        let is_dir = metadata.is_dir();
+        if is_dir || metadata.is_file() {
+            Ok(PathElement {
+                name: value.file_name().into_string().unwrap(),
+                is_dir,
+                children: load_children(value.path(), nesting, is_dir).await?,
+            })
+        } else {
+            error!(
+                "File <{:?}> is neither a directory nor a file. ",
+                value.file_name()
+            );
+            Err(
+                ProblemDetails::from_status_code(StatusCode::INTERNAL_SERVER_ERROR)
+                    .with_detail(errors::ERROR_DETAILS_INTERNAL_ERROR),
+            )
+        }
+    }
+}
+
+async fn load_children(
+    path: PathBuf,
+    nesting: u32,
+    is_dir: bool,
+) -> Result<Option<Vec<PathElement>>, ProblemDetails> {
+    if nesting == 0 {
+        Ok(None)
+    } else if !is_dir {
+        Ok(Some(vec![]))
+    } else {
+        Ok(Some(Box::pin(load_directory(path, nesting - 1)).await?))
+    }
+}

casket-backend/src/files/mod.rs

@@ -0,0 +1,121 @@
+use crate::errors;
+use axum::http::StatusCode;
+use problem_details::ProblemDetails;
+use std::path::{Component, Path, PathBuf};
+
+pub mod list;
+pub mod upload;
+
+fn build_system_path(
+    base_directory: &Path,
+    user_id: &str,
+    user_path: &PathBuf,
+) -> Result<PathBuf, ProblemDetails> {
+    if user_path.is_absolute() {
+        Err(
+            ProblemDetails::from_status_code(StatusCode::BAD_REQUEST).with_detail(
+                errors::ERROR_DETAILS_ABSOLUTE_PATH_NOT_ALLOWED.to_owned()
+                    + format!(" Provided Path: {user_path:?}",).as_str(),
+            ),
+        )
+    } else {
+        sanitize_path(&base_directory.join(user_id).join(user_path))
+    }
+}
+
+pub fn sanitize_path(path: &Path) -> Result<PathBuf, ProblemDetails> {
+    let mut ret = PathBuf::new();
+    for component in path.components().peekable() {
+        match component {
+            Component::Prefix(..) => unreachable!(),
+            Component::RootDir => {
+                ret.push(Component::RootDir);
+            }
+            Component::CurDir => {}
+            Component::ParentDir => {
+                return Err(ProblemDetails::from_status_code(StatusCode::BAD_REQUEST)
+                    .with_detail(errors::ERROR_DETAILS_PATH_TRAVERSAL));
+            }
+            Component::Normal(c) => {
+                ret.push(c);
+            }
+        }
+    }
+    Ok(ret)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_sanitize_path_success() {
+        let cases = &[
+            ("", ""),
+            (".", ""),
+            (".////./.", ""),
+            ("/", "/"),
+            ("/foo/bar", "/foo/bar"),
+            ("/foo/bar/", "/foo/bar"),
+            ("/foo/bar/./././///", "/foo/bar"),
+            ("foo/bar", "foo/bar"),
+            ("foo/bar/", "foo/bar"),
+            ("foo/bar/./././///", "foo/bar"),
+        ];
+        for (input, expected) in cases {
+            let actual = sanitize_path(&PathBuf::from(input));
+            assert_eq!(actual, Ok(PathBuf::from(expected)), "input: {input}");
+        }
+    }
+
+    #[test]
+    fn test_sanitize_path_error() {
+        let cases = &[
+            "..",
+            "/../",
+            "../../foo/bar",
+            "../../foo/bar/",
+            "../../foo/bar/./././///",
+            "../../foo/bar/..",
+            "../../foo/bar/../..",
+            "../../foo/bar/../../..",
+            "/foo/bar/../../..",
+            "/foo/bar/../..",
+            "/foo/bar/..",
+        ];
+        for input in cases {
+            let actual = sanitize_path(&PathBuf::from(input));
+            assert_eq!(
+                actual,
+                Err(ProblemDetails::from_status_code(StatusCode::BAD_REQUEST)
+                    .with_detail(errors::ERROR_DETAILS_PATH_TRAVERSAL)),
+                "input: {input}"
+            );
+        }
+    }
+
+    #[test]
+    fn test_build_system_path_success() {
+        let input_path = PathBuf::from("tmp/blub");
+        let user_id = "bla";
+        assert_eq!(
+            build_system_path(&PathBuf::from("/tmp/bla"), user_id, &input_path).unwrap(),
+            PathBuf::from("/tmp/bla/bla/tmp/blub")
+        );
+    }
+
+    #[test]
+    fn test_build_system_path_error_with_absolute_user_path_returns_error() {
+        let input_path = PathBuf::from("tmp/blub");
+        let user_id = "bla";
+        assert_eq!(
+            build_system_path(&PathBuf::from("/tmp/bla"), user_id, &input_path),
+            Err(
+                ProblemDetails::from_status_code(StatusCode::BAD_REQUEST).with_detail(
+                    errors::ERROR_DETAILS_ABSOLUTE_PATH_NOT_ALLOWED.to_owned()
+                        + format!(" Provided Path: {:?}", input_path).as_str()
+                )
+            )
+        );
+    }
+}

casket-backend/src/files/upload.rs

@@ -0,0 +1,70 @@
+use crate::errors::to_internal_error;
+use crate::files::build_system_path;
+use crate::{errors, AppState};
+use axum::body::Bytes;
+use axum::debug_handler;
+use axum::extract::multipart::{Field, MultipartError};
+use axum::extract::{Multipart, State};
+use axum::http::StatusCode;
+use futures::Stream;
+use futures_util::stream::MapErr;
+use futures_util::{StreamExt, TryStreamExt};
+use problem_details::ProblemDetails;
+use std::io;
+use std::io::Error;
+use std::path::PathBuf;
+use tokio::fs::{create_dir_all, File};
+use tokio::io::AsyncWriteExt;
+
+#[debug_handler]
+pub async fn handle_file_uploads(
+    State(state): State<AppState>,
+    axum::extract::Path(user_id): axum::extract::Path<String>,
+    mut multipart: Multipart,
+) -> Result<(), ProblemDetails> {
+    loop {
+        let next = multipart.next_field().await;
+        match next {
+            Err(error) => return Err(to_internal_error(error)),
+            Ok(Some(field)) => handle_single_file_upload(&state, &user_id, field).await?,
+            Ok(None) => return Ok(()),
+        }
+    }
+}
+
+// clippy behaves weird. When removing the lifetime the compilation fails since the Field type has
+// a generic lifetime around the multipart.
+#[allow(clippy::needless_lifetimes)]
+async fn handle_single_file_upload<'field_lifetime>(
+    state: &AppState,
+    user_id: &str,
+    field: Field<'field_lifetime>,
+) -> Result<(), ProblemDetails> {
+    match field.name() {
+        None | Some("") => Err(ProblemDetails::from_status_code(StatusCode::BAD_REQUEST)
+            .with_detail(errors::ERROR_DETAILS_NO_NAME_PROVIDED_MULTIPART_FIELD)),
+        Some(field_name) => {
+            let path = PathBuf::from(field_name);
+            let filesystem_path = build_system_path(&state.config.files.directory, user_id, &path)?;
+            save_file(filesystem_path, map_error_to_io_error(field))
+                .await
+                .map_err(to_internal_error)
+        }
+    }
+}
+
+pub async fn save_file(
+    path: PathBuf,
+    mut content: impl Stream<Item = Result<Bytes, Error>> + Unpin,
+) -> Result<(), Error> {
+    create_dir_all(path.parent().unwrap()).await?;
+    let mut file = File::create(path).await?;
+    while let Some(bytes) = content.next().await {
+        file.write_all(&bytes?).await?;
+    }
+    Ok(())
+}
+
+fn map_error_to_io_error(field: Field) -> MapErr<Field, fn(MultipartError) -> Error> {
+    field.map_err(|err| Error::new(io::ErrorKind::Other, err))
+}

casket-backend/src/main.rs

@@ -1,33 +1,56 @@
+#![warn(clippy::pedantic)]
+
 mod config;
+mod errors;
+mod files;
 mod routes;
+mod extractor_helper;
 
 use axum::Router;
+use std::env;
+use std::process::exit;
+use std::str::FromStr;
+use tracing::{debug, error, info};
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct AppState {
     config: config::Config,
 }
 
 #[tokio::main]
 async fn main() {
+    tracing_subscriber::fmt()
+        .with_max_level(get_log_level())
+        .init();
     let config = config::get_config();
     match config {
         Ok(config) => {
-            println!("Loaded config: {:#?}", &config);
+            debug!("Config loaded {:?}", &config,);
-            // build our application with a route
+            let bind = format!("{}:{}", &config.server.bind_address, &config.server.port);
             let app = Router::new()
                 .merge(routes::routes())
                 .with_state(AppState { config });
 
-            // run it
+            let listener = tokio::net::TcpListener::bind(bind).await.unwrap();
-            let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
+            info!("listening on {}", listener.local_addr().unwrap());
-                .await
-                .unwrap();
-            println!("listening on {}", listener.local_addr().unwrap());
             axum::serve(listener, app).await.unwrap();
         }
         Err(error) => {
-            println!("Error while loading config: {}", error);
+            error!(
+                "Error while loading config: {}. Tried loading from the following files {:?} and env variables prefixed by CASKET_.",
+                error,
+                config::CONFIG_LOCATIONS
+            );
+            exit(1)
         }
     }
 }
+
+fn get_log_level() -> tracing::Level {
+    let env = env::var("CASKET_LOG_LEVEL");
+    match env {
+        Ok(value) => tracing::Level::from_str(&value)
+            .unwrap_or_else(|_| panic!("Failed to parse log level env {value}")),
+        Err(_) => tracing::Level::INFO,
+    }
+}

casket-backend/src/routes.rs

@@ -0,0 +1,16 @@
+use crate::files;
+use crate::AppState;
+use axum::routing::post;
+use axum::{response::Html, routing::get, Router};
+use files::list::query_file_tree;
+
+pub fn routes() -> Router<AppState> {
+    Router::new().route("/", get(handler)).route(
+        "/api/v1/user/{:user_id}/files",
+        post(files::upload::handle_file_uploads).get(query_file_tree),
+    )
+}
+
+async fn handler() -> Html<&'static str> {
+    Html("<h1>Hello, World!</h1>")
+}

casket-backend/src/routes/mod.rs

@@ -1,11 +0,0 @@
-use axum::{response::Html, routing::get, Router};
-
-use crate::AppState;
-
-pub fn routes() -> Router<AppState> {
-    Router::new().route("/", get(handler))
-}
-
-async fn handler() -> Html<&'static str> {
-    Html("<h1>Hello, World!</h1>")
-}