Implement client.port extraction in HTTP server instrumentations

instrumentation-api-semconv/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/http/ClientAddressAndPortExtractor.java

@@ -5,11 +5,8 @@
 
 package io.opentelemetry.instrumentation.api.instrumenter.http;
 
-import static io.opentelemetry.instrumentation.api.instrumenter.http.ForwardedHeaderParser.extractClientIpFromForwardedForHeader;
-import static io.opentelemetry.instrumentation.api.instrumenter.http.ForwardedHeaderParser.extractClientIpFromForwardedHeader;
-import static io.opentelemetry.instrumentation.api.instrumenter.http.HttpCommonAttributesExtractor.firstHeaderValue;
-
 import io.opentelemetry.instrumentation.api.instrumenter.network.internal.FallbackAddressPortExtractor;
+import java.util.Locale;
 
 final class ClientAddressAndPortExtractor<REQUEST>
     implements FallbackAddressPortExtractor<REQUEST> {
@@ -23,21 +20,139 @@ final class ClientAddressAndPortExtractor<REQUEST>
   @Override
   public void extract(AddressPortSink sink, REQUEST request) {
     // try Forwarded
-    String forwarded = firstHeaderValue(getter.getHttpRequestHeader(request, "forwarded"));
-    if (forwarded != null) {
-      forwarded = extractClientIpFromForwardedHeader(forwarded);
-      if (forwarded != null) {
-        sink.setAddress(forwarded);
+    for (String forwarded : getter.getHttpRequestHeader(request, "forwarded")) {
+      if (extractFromForwardedHeader(sink, forwarded)) {
         return;
       }
     }
 
     // try X-Forwarded-For
-    forwarded = firstHeaderValue(getter.getHttpRequestHeader(request, "x-forwarded-for"));
-    if (forwarded != null) {
-      sink.setAddress(extractClientIpFromForwardedForHeader(forwarded));
+    for (String forwardedFor : getter.getHttpRequestHeader(request, "x-forwarded-for")) {
+      if (extractFromForwardedForHeader(sink, forwardedFor)) {
+        return;
+      }
+    }
+  }
+
+  private static boolean extractFromForwardedHeader(AddressPortSink sink, String forwarded) {
+    int start = forwarded.toLowerCase(Locale.ROOT).indexOf("for=");
+    if (start < 0) {
+      return false;
+    }
+    start += 4; // start is now the index after for=
+    if (start >= forwarded.length() - 1) { // the value after for= must not be empty
+      return false;
+    }
+    // find the end of the `for=<address>` section
+    int end = forwarded.indexOf(';', start);
+    if (end < 0) {
+      end = forwarded.length();
+    }
+    return extractClientInfo(sink, forwarded, start, end);
+  }
+
+  private static boolean extractFromForwardedForHeader(AddressPortSink sink, String forwardedFor) {
+    return extractClientInfo(sink, forwardedFor, 0, forwardedFor.length());
+  }
+
+  // from https://www.rfc-editor.org/rfc/rfc7239
+  //  "Note that IPv6 addresses may not be quoted in
+  //   X-Forwarded-For and may not be enclosed by square brackets, but they
+  //   are quoted and enclosed in square brackets in Forwarded"
+  // and also (applying to Forwarded but not X-Forwarded-For)
+  //  "It is important to note that an IPv6 address and any nodename with
+  //   node-port specified MUST be quoted, since ':' is not an allowed
+  //   character in 'token'."
+  private static boolean extractClientInfo(
+      AddressPortSink sink, String forwarded, int start, int end) {
+    if (start >= end) {
+      return false;
+    }
+
+    // skip quotes
+    if (forwarded.charAt(start) == '"') {
+      // try to find the end of the quote
+      int quoteEnd = forwarded.indexOf('"', start + 1);
+      if (notFound(quoteEnd, end)) {
+        // malformed header value
+        return false;
+      }
+      return extractClientInfo(sink, forwarded, start + 1, quoteEnd);
+    }
+
+    // ipv6 address enclosed in square brackets case
+    if (forwarded.charAt(start) == '[') {
+      int ipv6End = forwarded.indexOf(']', start + 1);
+      if (notFound(ipv6End, end)) {
+        // malformed header value
+        return false;
+      }
+      sink.setAddress(forwarded.substring(start + 1, ipv6End));
+
+      int portStart = ipv6End + 1;
+      if (portStart < end && forwarded.charAt(portStart) == ':') {
+        int portEnd = findPortEnd(forwarded, portStart + 1, end);
+        setPort(sink, forwarded, portStart + 1, portEnd);
+      }
+
+      return true;
+    }
+
+    // try to match either ipv4 or ipv6 without brackets
+    boolean inIpv4 = false;
+    for (int i = start; i < end; ++i) {
+      char c = forwarded.charAt(i);
+
+      // dots only appear in ipv4
+      if (c == '.') {
+        inIpv4 = true;
+      }
+
+      // find the character terminating the address
+      boolean isIpv4PortSeparator = inIpv4 && c == ':';
+      if (c == ',' || c == ';' || c == '"' || isIpv4PortSeparator) {
+        // empty string
+        if (i == start) {
+          return false;
+        }
+
+        sink.setAddress(forwarded.substring(start, i));
+
+        if (isIpv4PortSeparator) {
+          int portStart = i;
+          int portEnd = findPortEnd(forwarded, portStart + 1, end);
+          setPort(sink, forwarded, portStart + 1, portEnd);
+        }
+
+        return true;
+      }
+    }
+
+    // just an address without a port
+    sink.setAddress(forwarded.substring(start, end));
+    return true;
+  }
+
+  private static boolean notFound(int pos, int end) {
+    return pos < 0 || pos >= end;
+  }
+
+  private static int findPortEnd(String header, int start, int end) {
+    int numberEnd = start;
+    while (numberEnd < end && Character.isDigit(header.charAt(numberEnd))) {
+      ++numberEnd;
     }
+    return numberEnd;
+  }
 
-    // TODO: client.port will be implemented in a future PR
+  private static void setPort(AddressPortSink sink, String header, int start, int end) {
+    if (start == end) {
+      return;
+    }
+    try {
+      sink.setPort(Integer.parseInt(header.substring(start, end)));
+    } catch (NumberFormatException ignored) {
+      // malformed port, ignoring
+    }
   }
 }