Fixed issue: NETTY-237 java.lang.IllegalArgumentException when passing HTTP 1.1 spec compliant LWS separated HTTP header values

* Relaxed HTTP header value validation

src/main/java/org/jboss/netty/handler/codec/http/DefaultHttpMessage.java

@@ -54,9 +54,6 @@ public class DefaultHttpMessage implements HttpMessage {
     public void addHeader(final String name, final String value) {
         validateHeaderName(name);
         validateHeaderValue(value);
-        if (value == null) {
-            throw new NullPointerException("value is null");
-        }
         if (headers.get(name) == null) {
             headers.put(name, new ArrayList<String>(1));
         }
@@ -66,10 +63,6 @@ public class DefaultHttpMessage implements HttpMessage {
     public void setHeader(final String name, final String value) {
         validateHeaderName(name);
         validateHeaderValue(value);
-        if (value == null) {
-            throw new NullPointerException("value");
-        }
-
         List<String> values = new ArrayList<String>(1);
         values.add(value);
         headers.put(name, values);
@@ -129,16 +122,62 @@ public class DefaultHttpMessage implements HttpMessage {
         if (value == null) {
             throw new NullPointerException("value");
         }
+
+        // 0 - the previous character was neither CR nor LF
+        // 1 - the previous character was CR
+        // 2 - the previous character was LF
+        int state = 0;
+
         for (int i = 0; i < value.length(); i ++) {
             char c = value.charAt(i);
-            // Check prohibited characters.
+
+            // Check the absolutely prohibited characters.
             switch (c) {
-            case '\r': case '\n': case '\f':
+            case '\f':
+                throw new IllegalArgumentException(
+                        "value contains a prohibited character '\\f': " + value);
             case 0x0b: // Vertical tab
                 throw new IllegalArgumentException(
-                        "value contains one of the following prohibited characters: " +
+                        "value contains a prohibited character '\\v': " + value);
-                        "\\r\\n\\v\\f: " + value);
             }
+
+            // Check the CRLF (HT | SP) pattern
+            switch (state) {
+            case 0:
+                switch (c) {
+                case '\r':
+                    state = 1;
+                    break;
+                case '\n':
+                    state = 2;
+                    break;
+                }
+                break;
+            case 1:
+                switch (c) {
+                case '\n':
+                    state = 2;
+                    break;
+                default:
+                    throw new IllegalArgumentException(
+                            "Only '\\n' is allowed after '\\r': " + value);
+                }
+                break;
+            case 2:
+                switch (c) {
+                case ' ': case '\t':
+                    state = 0;
+                    break;
+                default:
+                    throw new IllegalArgumentException(
+                            "Only ' ' and '\\t' are allowed after '\\n': " + value);
+                }
+            }
+        }
+
+        if (state != 0) {
+            throw new IllegalArgumentException(
+                    "value must not end with '\\r' or '\\n':" + value);
         }
     }