utils: Add password authentication for (non-proxy) servers

For now, only support authentication stored in .netrc files [1] in plain
text as that is also support by the Git CLI which still gets called in
Git.kt.

Resolves #2580.

[1] https://www.gnu.org/software/inetutils/manual/html_node/The-_002enetrc-file.html

Signed-off-by: Sebastian Schuberth <sebastian.schuberth@bosch.io>

Author: sschuberth

utils/src/main/kotlin/OrtAuthenticator.kt

@@ -74,15 +74,54 @@ class OrtAuthenticator(private val original: Authenticator? = null) : Authentica
     }
 
     override fun getPasswordAuthentication(): PasswordAuthentication? {
-        if (requestorType == RequestorType.PROXY) {
-            val proxySelector = ProxySelector.getDefault()
-            if (proxySelector is OrtProxySelector) {
-                val type = requestingProtocol.toProxyType() ?: return null
-                val proxy = Proxy(type, InetSocketAddress(requestingHost, requestingPort))
-                return proxySelector.getProxyAuthentication(proxy)
+        when (requestorType) {
+            RequestorType.PROXY -> {
+                val proxySelector = ProxySelector.getDefault()
+                if (proxySelector is OrtProxySelector) {
+                    val type = requestingProtocol.toProxyType() ?: return null
+                    val proxy = Proxy(type, InetSocketAddress(requestingHost, requestingPort))
+                    return proxySelector.getProxyAuthentication(proxy)
+                }
+            }
+
+            RequestorType.SERVER -> {
+                val netrcFile = getUserHomeDirectory().resolve(".netrc")
+                if (netrcFile.isFile) {
+                    getNetrcAuthentication(netrcFile.readText(), requestingHost)?.let { return it }
+                }
+
+                // TODO: Add support for .authinfo files (which use the same syntax as .netrc files) once Git.kt does
+                //       not call the Git CLI anymore which only suuports .netrc files.
             }
+
+            null -> log.warn { "No requestor type set for password authentication." }
         }
 
         return super.getPasswordAuthentication()
     }
 }
+
+fun getNetrcAuthentication(contents: String, machine: String): PasswordAuthentication? {
+    val lines = contents.lines().mapNotNull { line ->
+        line.trim().takeUnless { it.startsWith('#') }
+    }
+
+    val iterator = lines.joinToString(" ").split(Regex("\\s")).iterator()
+
+    var machineFound = false
+    var login: String? = null
+    var password: String? = null
+
+    while (iterator.hasNext()) {
+        when (iterator.next()) {
+            "machine" -> machineFound = iterator.hasNext() && iterator.next() == machine
+            "login" -> login = if (machineFound && iterator.hasNext()) iterator.next() else null
+            "password" -> password = if (machineFound && iterator.hasNext()) iterator.next() else null
+            "default" -> machineFound = true
+        }
+
+        if (login != null && password != null) return PasswordAuthentication(login, password.toCharArray())
+    }
+
+    return null
+}

utils/src/test/kotlin/OrtAuthenticatorTest.kt

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2020 Bosch.IO GmbH
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * License-Filename: LICENSE
+ */
+
+package org.ossreviewtoolkit.utils
+
+import io.kotest.core.spec.style.WordSpec
+import io.kotest.matchers.shouldBe
+import io.kotest.matchers.shouldNotBe
+
+class OrtAuthenticatorTest : WordSpec({
+    "getNetrcAuthentication()" should {
+        "correctly parse single-line contents" {
+            val authentication = getNetrcAuthentication("""
+                machine github.com login foo password bar
+            """.trimIndent(), "github.com")
+
+            authentication shouldNotBe null
+            authentication!!.userName shouldBe "foo"
+            authentication.password shouldBe "bar".toCharArray()
+        }
+
+        "correctly parse multi-line contents" {
+            val authentication = getNetrcAuthentication("""
+                machine gitlab.com
+                login foo
+                password bar
+            """.trimIndent(), "gitlab.com")
+
+            authentication shouldNotBe null
+            authentication!!.userName shouldBe "foo"
+            authentication.password shouldBe "bar".toCharArray()
+        }
+
+        "recognize the default machine" {
+            val authentication = getNetrcAuthentication("""
+                machine github.com
+                login git
+                password hub
+                default login foo password bar
+            """.trimIndent(), "gitlab.com")
+
+            authentication shouldNotBe null
+            authentication!!.userName shouldBe "foo"
+            authentication.password shouldBe "bar".toCharArray()
+        }
+
+        "ignore superfluous statements" {
+            val authentication = getNetrcAuthentication("""
+                machine "# A funky way to add comments."
+                login funkyLogin
+                password funkyPassword
+                machine bitbucket.com
+                # This is a port.
+                port 433
+                password bar
+                login foo
+            """.trimIndent(), "bitbucket.com")
+
+            authentication shouldNotBe null
+            authentication!!.userName shouldBe "foo"
+            authentication.password shouldBe "bar".toCharArray()
+        }
+
+        "ignore irrelavant machines" {
+            val authentication = getNetrcAuthentication("""
+                machine bitbucket.com login foo password bar
+            """.trimIndent(), "github.com")
+
+            authentication shouldBe null
+        }
+    }
+})