8305763: Parsing a URI with an underscore goes through a silent exception, negatively impacting performance

Backport-of: 749d4801937ac145f945765f0ba0980bbccf384f

Author: Dhamoder Nalla

src/java.base/share/classes/java/net/URI.java

@@ -3193,6 +3193,7 @@ private int parseAuthority(int start, int n)
 
             boolean serverChars;
             boolean regChars;
+            boolean skipParseException;
 
             if (scan(p, n, "]") > p) {
                 // contains a literal IPv6 address, therefore % is allowed
@@ -3208,15 +3209,28 @@ private int parseAuthority(int start, int n)
                 return n;
             }
 
+            // When parsing a URI, skip creating exception objects if the server-based
+            // authority is not required and the registry parse is successful.
+            //
+            skipParseException = (!requireServerAuthority && regChars);
             if (serverChars) {
                 // Might be (probably is) a server-based authority, so attempt
                 // to parse it as such.  If the attempt fails, try to treat it
                 // as a registry-based authority.
                 try {
-                    q = parseServer(p, n);
-                    if (q < n)
-                        failExpecting("end of authority", q);
-                    authority = input.substring(p, n);
+                    q = parseServer(p, n, skipParseException);
+                    if (q < n) {
+                        if (skipParseException) {
+                            userInfo = null;
+                            host = null;
+                            port = -1;
+                            q = p;
+                        } else {
+                            failExpecting("end of authority", q);
+                        }
+                    } else {
+                        authority = input.substring(p, n);
+                    }
                 } catch (URISyntaxException x) {
                     // Undo results of failed parse
                     userInfo = null;
@@ -3254,7 +3268,7 @@ private int parseAuthority(int start, int n)
 
         // [<userinfo>@]<host>[:<port>]
         //
-        private int parseServer(int start, int n)
+        private int parseServer(int start, int n, boolean skipParseException)
             throws URISyntaxException
         {
             int p = start;
@@ -3294,7 +3308,7 @@ private int parseServer(int start, int n)
             } else {
                 q = parseIPv4Address(p, n);
                 if (q <= p)
-                    q = parseHostname(p, n);
+                    q = parseHostname(p, n, skipParseException);
                 p = q;
             }
 
@@ -3311,7 +3325,10 @@ private int parseServer(int start, int n)
                     }
                     p = q;
                 }
+            } else if (p < n && skipParseException) {
+                return p;
             }
+
             if (p < n)
                 failExpecting("port number", p);
 
@@ -3416,7 +3433,7 @@ private int parseIPv4Address(int start, int n) {
         // domainlabel   = alphanum | alphanum *( alphanum | "-" ) alphanum
         // toplabel      = alpha | alpha *( alphanum | "-" ) alphanum
         //
-        private int parseHostname(int start, int n)
+        private int parseHostname(int start, int n, boolean skipParseException)
             throws URISyntaxException
         {
             int p = start;
@@ -3444,9 +3461,12 @@ private int parseHostname(int start, int n)
                 p = q;
             } while (p < n);
 
-            if ((p < n) && !at(p, n, ':'))
+            if ((p < n) && !at(p, n, ':')) {
+                if (skipParseException) {
+                    return p;
+                }
                 fail("Illegal character in hostname", p);
-
+            }
             if (l < 0)
                 failExpecting("hostname", start);