Add support of SOCKS proxies for S3 repository (opensearch-project#2160)

Signed-off-by: Andrey Pleskach <ples@aiven.io>

plugins/repository-s3/src/main/java/org/opensearch/repositories/s3/ProxySettings.java

@@ -0,0 +1,123 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.repositories.s3;
+
+import com.amazonaws.Protocol;
+import org.opensearch.common.Strings;
+import org.opensearch.common.settings.SettingsException;
+
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.UnknownHostException;
+import java.util.Objects;
+
+public class ProxySettings {
+    public static final ProxySettings NO_PROXY_SETTINGS = new ProxySettings(ProxyType.DIRECT, null, -1, null, null);
+
+    public static enum ProxyType {
+        HTTP(Protocol.HTTP.name()),
+        HTTPS(Protocol.HTTPS.name()),
+        SOCKS("SOCKS"),
+        DIRECT("DIRECT");
+
+        private final String name;
+
+        private ProxyType(String name) {
+            this.name = name;
+        }
+
+        public Protocol toProtocol() {
+            if (this == DIRECT) {
+                // We check it in settings,
+                // the probability that it could be thrown is small, but how knows
+                throw new SettingsException("Couldn't convert to S3 protocol");
+            } else if (this == SOCKS) {
+                throw new SettingsException("Couldn't convert to S3 protocol. SOCKS is not supported");
+            }
+            return Protocol.valueOf(name());
+        }
+
+    }
+
+    private final ProxyType type;
+
+    private final String host;
+
+    private final String username;
+
+    private final String password;
+
+    private final int port;
+
+    public String getHost() {
+        return host;
+    }
+
+    public ProxySettings(final ProxyType type, final String host, final int port, final String username, final String password) {
+        this.type = type;
+        this.host = host;
+        this.port = port;
+        this.username = username;
+        this.password = password;
+    }
+
+    public ProxyType getType() {
+        return this.type;
+    }
+
+    public String getHostName() {
+        return host;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public InetSocketAddress getAddress() {
+        try {
+            return new InetSocketAddress(InetAddress.getByName(host), port);
+        } catch (UnknownHostException e) {
+            // this error won't be thrown since validation of the host name is in the S3ClientSettings
+            throw new RuntimeException(e);
+        }
+    }
+
+    public String getUsername() {
+        return this.username;
+    }
+
+    public String getPassword() {
+        return this.password;
+    }
+
+    public boolean isAuthenticated() {
+        return Strings.isNullOrEmpty(username) == false && Strings.isNullOrEmpty(password) == false;
+    }
+
+    public ProxySettings recreateWithNewHostAndPort(final String host, final int port) {
+        return new ProxySettings(type, host, port, username, password);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        final ProxySettings that = (ProxySettings) o;
+        return port == that.port
+            && type == that.type
+            && Objects.equals(host, that.host)
+            && Objects.equals(username, that.username)
+            && Objects.equals(password, that.password);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(type, host, username, password, port);
+    }
+}