Improves AS number parameter parsing

 * AS0 is an allowed value. This is used for unknown AS numbers.
 * Leading zeros are stripped from the AS number.
 * If an AS number is larger than the maximum possible (in 32-bits)
   then this will be treated as an error.
 * Tests are increased to cover additional cases.

Fixes: #27163

CHANGELOG.md

+# Changes in version 6.2-1.17.1 - 2018-08-??
+
+ * Minor changes
+   - Parsing of the "as" parameter allows AS0 to be specified. It will now
+     strip leading zeros. Specifying an AS number larger than the maximum
+     possible with 32-bits will be treated as an error.
+
 # Changes in version 6.2-1.17.0 - 2018-08-16
 
  * Medium changes

src/main/java/org/torproject/onionoo/server/ResourceServlet.java

@@ -502,7 +502,7 @@ public class ResourceServlet extends HttpServlet {
   }
 
   private static Pattern asNumberParameterPattern =
-      Pattern.compile("((^|,)([aA][sS])?[1-9][0-9]{0,9})+$");
+      Pattern.compile("((^|,)([aA][sS])?0*[0-9]{1,10})+$");
 
   private String[] parseAsNumberParameter(String parameter) {
     if (!asNumberParameterPattern.matcher(parameter).matches()) {
@@ -512,8 +512,14 @@ public class ResourceServlet extends HttpServlet {
     String[] parameterParts = parameter.toUpperCase().split(",");
     String[] parsedParameter = new String[parameterParts.length];
     for (int i = 0; i < parameterParts.length; i++) {
-      parsedParameter[i] = (!parameterParts[i].startsWith("AS") ? "AS" : "")
-          + parameterParts[i];
+      boolean asPrefix = parameterParts[i].startsWith("AS");
+      Long asNumber = Long.parseLong(asPrefix
+          ? parameterParts[i].substring(2) : parameterParts[i]);
+      if (asNumber > 4294967295L) {
+        /* AS number was too large */
+        return null;
+      }
+      parsedParameter[i] = "AS" + asNumber.toString();
     }
     return parsedParameter;
   }

src/test/java/org/torproject/onionoo/server/ResourceServletTest.java

@@ -178,7 +178,7 @@ public class ResourceServletTest {
         DateTimeHelper.parse("2013-04-22 20:00:00"), false,
         new TreeSet<>(Arrays.asList(new String[] { "Fast",
             "Running", "Unnamed", "V2Dir", "Valid" })), 63L, "a1",
-        DateTimeHelper.parse("2013-04-16 18:00:00"), "AS6830",
+        DateTimeHelper.parse("2013-04-16 18:00:00"), null,
         "liberty global operations b.v.",
         "1024d/51e2a1c7 \"steven j. murdoch\" "
         + "<tor+steven.murdoch@cl.cam.ac.uk> <fb-token:5sr_k_zs2wm=>",
@@ -1166,6 +1166,12 @@ public class ResourceServletTest {
         "/summary?as=as8767", 1, new String[] { "TorkaZ" }, 0, null);
   }
 
+  @Test(timeout = 100)
+  public void testAsas8767WithLeadingZeros() {
+    this.assertSummaryDocument(
+        "/summary?as=as008767", 1, new String[] { "TorkaZ" }, 0, null);
+  }
+
   @Test(timeout = 100)
   public void testAsAsSpace8767() {
     this.assertErrorStatusCode(
@@ -1178,6 +1184,34 @@ public class ResourceServletTest {
         new String[] { "TorkaZ", "Ferrari458" }, 0, null);
   }
 
+  @Test(timeout = 100)
+  public void testAsUnknown() {
+    this.assertSummaryDocument("/summary?as=0", 1,
+        new String[] {"TimMayTribute"}, 0, null);
+  }
+
+  @Test(timeout = 100)
+  public void testAsAsUnknown() {
+    this.assertSummaryDocument("/summary?as=as0", 1,
+        new String[] {"TimMayTribute"}, 0, null);
+  }
+
+  @Test(timeout = 100)
+  public void testAsAsUnknownWithLeadingZeros() {
+    this.assertSummaryDocument("/summary?as=as0000", 1,
+        new String[] {"TimMayTribute"}, 0, null);
+  }
+
+  @Test(timeout = 100)
+  public void testAsTooLarge() {
+    this.assertErrorStatusCode("/summary?as=4294967296", 400);
+  }
+
+  @Test(timeout = 100)
+  public void testAsNegative() {
+    this.assertErrorStatusCode("/summary?as=-3", 400);
+  }
+
   @Test(timeout = 100)
   public void testAsNameComcast() {
     this.assertSummaryDocument("/summary?as_name=Comcast", 1, null, 0, null);