Strip empty lines from downloaded cert chains

This fixes the "insufficient data" issue on IBMs crypto implementation.

README.md

@@ -41,4 +41,5 @@ _acme4j_ is open source software. The source code is distributed under the terms
 
 * I would like to thank Brian Campbell and all the other [jose4j](https://bitbucket.org/b_c/jose4j/wiki/Home) developers. _acme4j_ would not exist without your excellent work.
 * Thanks to [Daniel McCarney](https://github.com/cpu) for his help with the ACME protocol, Pebble, and Boulder.
+* [Ulrich Krause](https://github.com/eknori) for his help to make _acme4j_ run on IBM Java VMs.
 * I also like to thank [everyone who contributed to _acme4j_](https://github.com/shred/acme4j/graphs/contributors).

acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java

@@ -233,7 +233,7 @@ public class DefaultConnection implements Connection {
             throw new AcmeProtocolException("Unexpected content type: " + contentType);
         }
 
-        try (InputStream in = conn.getInputStream()) {
+        try (InputStream in = new TrimmingInputStream(conn.getInputStream())) {
             CertificateFactory cf = CertificateFactory.getInstance("X.509");
             return cf.generateCertificates(in).stream()
                     .map(c -> (X509Certificate) c)

acme4j-client/src/main/java/org/shredzone/acme4j/connector/TrimmingInputStream.java

@@ -0,0 +1,74 @@
+/*
+ * acme4j - Java ACME client
+ *
+ * Copyright (C) 2018 Richard "Shred" Körber
+ *   http://acme4j.shredzone.org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+package org.shredzone.acme4j.connector;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+
+/**
+ * Normalizes line separators in an InputStream. Converts all line separators to '\n'.
+ * Multiple line separators are compressed to a single line separator.
+ */
+@ParametersAreNonnullByDefault
+public class TrimmingInputStream extends InputStream {
+
+    private final InputStream in;
+    private boolean wasLineSeparator = true;
+
+    /**
+     * Creates a new {@link TrimmingInputStream}.
+     *
+     * @param in
+     *            {@link InputStream} to read from. Will be closed when this stream is
+     *            closed.
+     */
+    public TrimmingInputStream(InputStream in) {
+        this.in = in;
+    }
+
+    @Override
+    public int read() throws IOException {
+        int ch = in.read();
+
+        if (wasLineSeparator) {
+            while (isLineSeparator(ch)) {
+                ch = in.read();
+            }
+        }
+
+        wasLineSeparator = isLineSeparator(ch);
+
+        if (ch == '\r') {
+            ch = '\n';
+        }
+
+        return ch;
+    }
+
+    @Override
+    public void close() throws IOException {
+        in.close();
+        super.close();
+    }
+
+    /**
+     * Checks if the character is a line separator.
+     */
+    private static boolean isLineSeparator(int ch) {
+        return ch == '\n' || ch == '\r';
+    }
+
+}

acme4j-client/src/test/java/org/shredzone/acme4j/connector/TrimmingInputStreamTest.java

@@ -0,0 +1,64 @@
+/*
+ * acme4j - Java ACME client
+ *
+ * Copyright (C) 2018 Richard "Shred" Körber
+ *   http://acme4j.shredzone.org
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+package org.shredzone.acme4j.connector;
+
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Test;
+
+/**
+ * Unit tests for {@link TrimmingInputStream}.
+ */
+public class TrimmingInputStreamTest {
+
+    @Test
+    public void testEmpty() throws IOException {
+        String out = trimByStream("");
+        assertThat(out, is(""));
+    }
+
+    @Test
+    public void testTrim() throws IOException {
+        String out = trimByStream("\n\n"
+            + "Gallia est omnis divisa in partes tres,\r\n\r\n\r\n"
+            + "quarum unam incolunt Belgae, aliam Aquitani,\r\r\r\n\n"
+            + "tertiam, qui ipsorum lingua Celtae, nostra Galli appellantur.");
+        assertThat(out, is("Gallia est omnis divisa in partes tres,\n"
+            + "quarum unam incolunt Belgae, aliam Aquitani,\n"
+            + "tertiam, qui ipsorum lingua Celtae, nostra Galli appellantur."));
+    }
+
+    /**
+     * Trims a string by running it through the {@link TrimmingInputStream}.
+     */
+    private String trimByStream(String str) throws IOException {
+        StringBuilder out = new StringBuilder();
+
+        try (TrimmingInputStream in = new TrimmingInputStream(
+                        new ByteArrayInputStream(str.getBytes(StandardCharsets.US_ASCII)))) {
+            int ch;
+            while ((ch = in.read()) >= 0) {
+                out.append((char) ch);
+            }
+        }
+
+        return out.toString();
+    }
+
+}