fix: Fix json escaping in header values (#4031)

Author: adamspofford-dfinity

e2e/tests-dfx/assetscanister.bash

@@ -1897,6 +1897,28 @@ WARN: {
   assert_match '/somedir/upload-me.txt 1/1 \(8 bytes\) sha [0-9a-z]* \(with cache and 1 header\)'
 }
 
+@test "asset configuration via .ic-assets.json5 - respects weird characters" {
+  install_asset assetscanister
+  touch src/e2e_project_frontend/assets/thing.txt
+  cat <<'EOF' >src/e2e_project_frontend/assets/.ic-assets.json5
+[
+  {
+    "match": "thing.txt",
+    "headers": {
+      "X-Dummy-Header": "\"\'@%({[~$?\\"
+    }
+  }
+]
+EOF
+  dfx_start
+  assert_command dfx deploy
+  ID=$(dfx canister id e2e_project_frontend)
+  PORT=$(get_webserver_port)
+  assert_command curl --head "http://localhost:$PORT/thing.txt?canisterId=$ID"
+  # shellcheck disable=SC1003
+  assert_contains 'x-dummy-header: "'"'"'@%({[~$?\' 
+}
+
 @test "uses selected canister wasm" {
   dfx_start
   use_asset_wasm 0.12.1

src/canisters/frontend/ic-asset/src/asset/config.rs

@@ -337,7 +337,7 @@ mod rule_utils {
     use crate::error::LoadRuleError;
     use globset::{Glob, GlobMatcher};
     use itertools::Itertools;
-    use serde::{Deserialize, Serializer};
+    use serde::{de::Error as _, Deserialize, Serializer};
     use serde_json::Value;
     use std::collections::BTreeMap;
     use std::fmt;
@@ -387,12 +387,29 @@ mod rule_utils {
     where
         D: serde::Deserializer<'de>,
     {
-        match serde_json::value::Value::deserialize(deserializer)? {
-            Value::Object(v) => Ok(Maybe::Value(
-                v.into_iter()
-                    .map(|(k, v)| (k, v.to_string().trim_matches('"').to_string()))
-                    .collect::<BTreeMap<String, String>>(),
-            )),
+        match Value::deserialize(deserializer)? {
+            Value::Object(v) => {
+                Ok(Maybe::Value(
+                    v.into_iter()
+                        .map(|(k, v)| {
+                            Ok((
+                                k,
+                                match v {
+                                    Value::Bool(b) => b.to_string(),
+                                    Value::Number(n) => n.to_string(),
+                                    Value::String(s) => s, // v.to_string() would json-escape this
+                                    Value::Null => String::new(),
+                                    v => {
+                                        return Err(D::Error::custom(format!(
+                                            "headers must be strings, numbers, or bools (was {v:?})"
+                                        )))
+                                    }
+                                },
+                            ))
+                        })
+                        .collect::<Result<BTreeMap<String, String>, D::Error>>()?,
+                ))
+            }
             Value::Null => Ok(Maybe::Null),
             _ => Err(serde::de::Error::custom(
                 "wrong data format for field `headers` (only map or null are allowed)",