[credentialhelper] Add types to communicate with the subprocess

This change adds `GetCredentials{Request,Response}`, which we'll use to
pass data in `stdin` to the credental helper subprocess, and read the
response from `stdout` of the subprocess.

Progress on https://github.com/bazelbuild/proposals/blob/main/designs/2022-06-07-bazel-credential-helpers.md#proposal

Closes bazelbuild#15803.

PiperOrigin-RevId: 459701706
Change-Id: Icbd9fc491546ee5599d5a9d04680671b06a91a85

src/main/java/com/google/devtools/build/lib/authandtls/credentialhelper/BUILD

@@ -15,7 +15,9 @@ java_library(
     srcs = glob(["*.java"]),
     deps = [
         "//src/main/java/com/google/devtools/build/lib/vfs",
+        "//third_party:auto_value",
         "//third_party:error_prone_annotations",
+        "//third_party:gson",
         "//third_party:guava",
     ],
 )

src/main/java/com/google/devtools/build/lib/authandtls/credentialhelper/GetCredentialsRequest.java

@@ -0,0 +1,103 @@
+// Copyright 2022 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.authandtls.credentialhelper;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Preconditions;
+import com.google.errorprone.annotations.Immutable;
+import com.google.gson.JsonSyntaxException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.net.URI;
+import java.util.Locale;
+
+/**
+ * Request for the {@code get} command of the <a
+ * href="https://github.com/bazelbuild/proposals/blob/main/designs/2022-06-07-bazel-credential-helpers.md#proposal">Credential
+ * Helper Protocol</a>.
+ */
+@AutoValue
+@AutoValue.CopyAnnotations
+@Immutable
+@JsonAdapter(GetCredentialsRequest.GsonTypeAdapter.class)
+public abstract class GetCredentialsRequest {
+  /** Returns the {@link URI} this request is for. */
+  public abstract URI getUri();
+
+  /** Returns a new builder for {@link GetCredentialsRequest}. */
+  public static Builder newBuilder() {
+    return new AutoValue_GetCredentialsRequest.Builder();
+  }
+
+  /** Builder for {@link GetCredentialsRequest}. */
+  @AutoValue.Builder
+  public abstract static class Builder {
+    /** Sets the {@link URI} this request is for. */
+    public abstract Builder setUri(URI uri);
+
+    /** Returns the newly constructed {@link GetCredentialsRequest}. */
+    public abstract GetCredentialsRequest build();
+  }
+
+  /** GSON adapter for GetCredentialsRequest. */
+  public static final class GsonTypeAdapter extends TypeAdapter<GetCredentialsRequest> {
+    @Override
+    public void write(JsonWriter writer, GetCredentialsRequest value) throws IOException {
+      Preconditions.checkNotNull(writer);
+      Preconditions.checkNotNull(value);
+
+      writer.beginObject();
+      writer.name("uri").value(value.getUri().toString());
+      writer.endObject();
+    }
+
+    @Override
+    public GetCredentialsRequest read(JsonReader reader) throws IOException {
+      Preconditions.checkNotNull(reader);
+
+      Builder request = newBuilder();
+
+      if (reader.peek() != JsonToken.BEGIN_OBJECT) {
+        throw new JsonSyntaxException(
+            String.format(Locale.US, "Expected object, got %s", reader.peek()));
+      }
+      reader.beginObject();
+      while (reader.hasNext()) {
+        String name = reader.nextName();
+        switch (name) {
+          case "uri":
+            if (reader.peek() != JsonToken.STRING) {
+              throw new JsonSyntaxException(
+                  String.format(
+                      Locale.US, "Expected value of 'url' to be a string, got %s", reader.peek()));
+            }
+            request.setUri(URI.create(reader.nextString()));
+            break;
+
+          default:
+            // We intentionally ignore unknown keys to achieve forward compatibility with requests
+            // coming from newer tools.
+            reader.skipValue();
+        }
+      }
+      reader.endObject();
+      return request.build();
+    }
+  }
+}

src/main/java/com/google/devtools/build/lib/authandtls/credentialhelper/GetCredentialsResponse.java

@@ -0,0 +1,154 @@
+// Copyright 2022 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.authandtls.credentialhelper;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.annotations.Immutable;
+import com.google.gson.JsonSyntaxException;
+import com.google.gson.TypeAdapter;
+import com.google.gson.annotations.JsonAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.util.Locale;
+import java.util.Map;
+
+/**
+ * Response from the {@code get} command of the <a
+ * href="https://github.com/bazelbuild/proposals/blob/main/designs/2022-06-07-bazel-credential-helpers.md#proposal">Credential
+ * Helper Protocol</a>.
+ */
+@AutoValue
+@AutoValue.CopyAnnotations
+@Immutable
+@JsonAdapter(GetCredentialsResponse.GsonTypeAdapter.class)
+public abstract class GetCredentialsResponse {
+  /** Returns the headers to attach to the request. */
+  public abstract ImmutableMap<String, ImmutableList<String>> getHeaders();
+
+  /** Returns a new builder for {@link GetCredentialsRequest}. */
+  public static Builder newBuilder() {
+    return new AutoValue_GetCredentialsResponse.Builder();
+  }
+
+  /** Builder for {@link GetCredentialsResponse}. */
+  @AutoValue.Builder
+  public abstract static class Builder {
+    protected abstract ImmutableMap.Builder<String, ImmutableList<String>> headersBuilder();
+
+    /** Returns the newly constructed {@link GetCredentialsResponse}. */
+    public abstract GetCredentialsResponse build();
+  }
+
+  /** GSON adapter for GetCredentialsResponse. */
+  public static final class GsonTypeAdapter extends TypeAdapter<GetCredentialsResponse> {
+    @Override
+    public void write(JsonWriter writer, GetCredentialsResponse response) throws IOException {
+      Preconditions.checkNotNull(writer);
+      Preconditions.checkNotNull(response);
+
+      writer.beginObject();
+
+      ImmutableMap<String, ImmutableList<String>> headers = response.getHeaders();
+      if (!headers.isEmpty()) {
+        writer.name("headers");
+        writer.beginObject();
+        for (Map.Entry<String, ImmutableList<String>> entry : headers.entrySet()) {
+          writer.name(entry.getKey());
+
+          writer.beginArray();
+          for (String value : entry.getValue()) {
+            writer.value(value);
+          }
+          writer.endArray();
+        }
+        writer.endObject();
+      }
+      writer.endObject();
+    }
+
+    @Override
+    public GetCredentialsResponse read(JsonReader reader) throws IOException {
+      Preconditions.checkNotNull(reader);
+
+      GetCredentialsResponse.Builder response = newBuilder();
+
+      if (reader.peek() != JsonToken.BEGIN_OBJECT) {
+        throw new JsonSyntaxException(
+            String.format(Locale.US, "Expected object, got %s", reader.peek()));
+      }
+      reader.beginObject();
+
+      while (reader.hasNext()) {
+        String name = reader.nextName();
+        switch (name) {
+          case "headers":
+            if (reader.peek() != JsonToken.BEGIN_OBJECT) {
+              throw new JsonSyntaxException(
+                  String.format(
+                      Locale.US,
+                      "Expected value of 'headers' to be an object, got %s",
+                      reader.peek()));
+            }
+            reader.beginObject();
+
+            while (reader.hasNext()) {
+              String headerName = reader.nextName();
+              ImmutableList.Builder<String> headerValues = ImmutableList.builder();
+
+              if (reader.peek() != JsonToken.BEGIN_ARRAY) {
+                throw new JsonSyntaxException(
+                    String.format(
+                        Locale.US,
+                        "Expected value of '%s' header to be an array of strings, got %s",
+                        headerName,
+                        reader.peek()));
+              }
+              reader.beginArray();
+              for (int i = 0; reader.hasNext(); i++) {
+                if (reader.peek() != JsonToken.STRING) {
+                  throw new JsonSyntaxException(
+                      String.format(
+                          Locale.US,
+                          "Expected value %s of '%s' header to be a string, got %s",
+                          i,
+                          headerName,
+                          reader.peek()));
+                }
+                headerValues.add(reader.nextString());
+              }
+              reader.endArray();
+
+              response.headersBuilder().put(headerName, headerValues.build());
+            }
+
+            reader.endObject();
+            break;
+
+          default:
+            // We intentionally ignore unknown keys to achieve forward compatibility with responses
+            // coming from newer tools.
+            reader.skipValue();
+        }
+      }
+      reader.endObject();
+      return response.build();
+    }
+  }
+}

src/test/java/com/google/devtools/build/lib/authandtls/credentialhelper/BUILD

@@ -26,6 +26,7 @@ java_test(
         "//src/main/java/com/google/devtools/build/lib/vfs",
         "//src/main/java/com/google/devtools/build/lib/vfs:pathfragment",
         "//src/main/java/com/google/devtools/build/lib/vfs/inmemoryfs",
+        "//third_party:gson",
         "//third_party:guava",
         "//third_party:junit4",
         "//third_party:truth",

src/test/java/com/google/devtools/build/lib/authandtls/credentialhelper/GetCredentialsRequestTest.java

@@ -0,0 +1,116 @@
+// Copyright 2022 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.authandtls.credentialhelper;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
+import java.net.URI;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests for {@link GetCredentialsRequest}. */
+@RunWith(JUnit4.class)
+public class GetCredentialsRequestTest {
+  private static final Gson GSON = new Gson();
+
+  @Test
+  public void parseValid() {
+    assertThat(
+            GSON.fromJson("{\"uri\": \"http://example.com\"}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("http://example.com"));
+    assertThat(
+            GSON.fromJson("{\"uri\": \"https://example.com\"}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("https://example.com"));
+    assertThat(
+            GSON.fromJson("{\"uri\": \"grpc://example.com\"}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("grpc://example.com"));
+    assertThat(
+            GSON.fromJson("{\"uri\": \"grpcs://example.com\"}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("grpcs://example.com"));
+
+    assertThat(
+            GSON.fromJson("{\"uri\": \"uri-without-protocol\"}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("uri-without-protocol"));
+  }
+
+  @Test
+  public void parseMissingUri() {
+    assertThrows(JsonSyntaxException.class, () -> GSON.fromJson("{}", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"foo\": 1}", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"foo\": 1, \"bar\": 2}", GetCredentialsRequest.class));
+  }
+
+  @Test
+  public void parseNonStringUri() {
+    assertThrows(JsonSyntaxException.class, () -> GSON.fromJson("[]", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class, () -> GSON.fromJson("\"foo\"", GetCredentialsRequest.class));
+    assertThrows(JsonSyntaxException.class, () -> GSON.fromJson("1", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"uri\": 1}", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"uri\": {}}", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"uri\": []}", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"uri\": [\"https://example.com\"]}", GetCredentialsRequest.class));
+    assertThrows(
+        JsonSyntaxException.class,
+        () -> GSON.fromJson("{\"uri\": null}", GetCredentialsRequest.class));
+  }
+
+  @Test
+  public void parseWithExtraFields() {
+    assertThat(
+            GSON.fromJson(
+                    "{\"uri\": \"http://example.com\", \"foo\": 1}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("http://example.com"));
+    assertThat(
+            GSON.fromJson(
+                    "{\"foo\": 1, \"uri\": \"http://example.com\"}", GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("http://example.com"));
+    assertThat(
+            GSON.fromJson(
+                    "{\"uri\": \"http://example.com\", \"foo\": 1, \"bar\": {}}",
+                    GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("http://example.com"));
+    assertThat(
+            GSON.fromJson(
+                    "{\"foo\": 1, \"uri\": \"http://example.com\", \"bar\": []}",
+                    GetCredentialsRequest.class)
+                .getUri())
+        .isEqualTo(URI.create("http://example.com"));
+  }
+}