io.muserver.ForwardedHeader Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of mu-server Show documentation
Show all versions of mu-server Show documentation
A simple but powerful web server framework
package io.muserver;
import java.util.*;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptyMap;
/**
* Represents a Forwarded header as described by RFC-7239.
*/
public class ForwardedHeader {
private final String by;
private final String forValue;
private final String host;
private final String proto;
private final Map extensions;
/**
* Creates a new Forwarded Header. All values are optional.
* @param by The address of the node proxying the request, or null
* @param forValue The address of the client that initiated the request, or null
* @param host The host that the client used, or null
* @param proto The protocol the client used, or null
* @param extensions Any extensions, or null
*/
public ForwardedHeader(String by, String forValue, String host, String proto, Map extensions) {
this.by = by;
this.forValue = forValue;
this.host = host;
this.proto = proto;
this.extensions = extensions == null ? emptyMap() : extensions;
}
/**
* @return The interface where the request came in to the proxy server (e.g. the IP address of the reverse
* proxy that forwarded this request), or null if not specified.
*/
public String by() {
return by;
}
/**
* @return The interface where the request came in to the proxy server, e.g. the IP address of the client
* that originated the request), or null if not specified.
*/
public String forValue() {
return forValue;
}
/**
* @return The Host request header field as received by the proxy (e.g. the hostname used on the original
* request), or null if not specified.
*/
public String host() {
return host;
}
/**
* @return Indicates which protocol was used to make the request (typically "http" or "https"), or
* null if not specified.
*/
public String proto() {
return proto;
}
/**
* @return Values not covered by by, for, host, or proto.
*/
public Map extensions() {
return extensions;
}
private enum State {PARAM_NAME, PARAM_VALUE;}
/**
* Parses the value of a Forwarded header into an object.
* Where multiple reverse proxies have resulted in multiple Forwarded headers, the first
* value in the list should contain the information of the original request.
* Null or blank strings return an empty list.
* @param input The value to parse
* @return A list of ForwardedHeader objects
* @throws IllegalArgumentException The value cannot be parsed
*/
public static List fromString(String input) {
if (input == null || input.trim().isEmpty()) {
return emptyList();
}
StringBuilder buffer = new StringBuilder();
List results = new ArrayList<>();
int i = 0;
while (i < input.length()) {
LinkedHashMap extensions = null;
State state = State.PARAM_NAME;
String paramName = null;
String by = null;
String forValue = null;
String host = null;
String proto = null;
boolean isQuotedString = false;
headerValueLoop:
for (; i < input.length(); i++) {
char c = input.charAt(i);
if (state == State.PARAM_NAME) {
if (c == ',' && buffer.length() == 0) {
i++; // a semi-colon without an parameter, like "something;"
break headerValueLoop;
} else if (c == '=') {
paramName = buffer.toString();
buffer.setLength(0);
state = State.PARAM_VALUE;
} else if (ParseUtils.isTChar(c)) {
buffer.append(c);
} else if (ParseUtils.isOWS(c)) {
if (buffer.length() > 0) {
throw new IllegalArgumentException("Got whitespace in parameter name while in " + state + " - header was " + buffer);
}
} else {
throw new IllegalArgumentException("Got ascii " + ((int)c) + " while in " + state);
}
} else {
boolean isFirst = !isQuotedString && buffer.length() == 0;
if (isFirst && ParseUtils.isOWS(c)) {
// ignore it
} else if (isFirst && c == '"') {
isQuotedString = true;
} else {
if (isQuotedString) {
char lastChar = input.charAt(i - 1);
if (c == '\\') {
// don't append
} else if (lastChar == '\\') {
buffer.append(c);
} else if (c == '"') {
// this is the end, but we'll update on the next go
isQuotedString = false;
} else {
buffer.append(c);
}
} else {
if (c == ';') {
String val = buffer.toString();
switch (paramName.toLowerCase()) {
case "by":
by = val;
break;
case "for":
forValue = val;
break;
case "host":
host = val;
break;
case "proto":
proto = val;
break;
default:
if (extensions == null) {
extensions = new LinkedHashMap<>(); // keeps insertion order
}
extensions.put(paramName, val);
break;
}
buffer.setLength(0);
paramName = null;
state = State.PARAM_NAME;
} else if (c == ',') {
i++;
break headerValueLoop;
} else if (ParseUtils.isVChar(c)) {
buffer.append(c);
} else if (ParseUtils.isOWS(c)) {
// ignore it
} else {
throw new IllegalArgumentException("Got character code " + ((int) c) + " (" + c + ") while parsing parameter value");
}
}
}
}
}
switch (state) {
case PARAM_VALUE:
String val = buffer.toString();
switch (paramName.toLowerCase()) {
case "by":
by = val;
break;
case "for":
forValue = val;
break;
case "host":
host = val;
break;
case "proto":
proto = val;
break;
default:
if (extensions == null) {
extensions = new LinkedHashMap<>(); // keeps insertion order
}
extensions.put(paramName, val);
break;
}
buffer.setLength(0);
break;
default:
if (buffer.length() > 0) {
throw new IllegalArgumentException("Unexpected ending point at state " + state + " for " + input);
}
}
results.add(new ForwardedHeader(by, forValue, host, proto, extensions));
}
return results;
}
/**
* Converts the HeaderValue into a string, suitable for printing in an HTTP header.
*
* @return A String, such as "some-value" or "content-type:text/html;charset=UTF-8"
*/
public String toString() {
StringBuilder sb = new StringBuilder();
appendString(sb, "by", by);
appendString(sb, "for", forValue);
appendString(sb, "host", host);
appendString(sb, "proto", proto);
this.extensions().forEach((key, value) -> appendString(sb, key, value));
return sb.toString();
}
/**
* Converts a list of headers into a single string that can be put into a Forwarded header field.
* @param headers The headers to serialise
* @return An RFC-7239 compliant Forwarded header value.
*/
public static String toString(List headers) {
StringBuilder sb = new StringBuilder();
for (ForwardedHeader header : headers) {
if (sb.length() > 0) {
sb.append(", ");
}
sb.append(header.toString());
}
return sb.toString();
}
private static void appendString(StringBuilder sb, String key, String value) {
if (value == null) {
return;
}
if (sb.length() > 0) {
sb.append(';');
}
sb.append(key).append('=').append(ParseUtils.quoteIfNeeded(value));
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ForwardedHeader that = (ForwardedHeader) o;
return Objects.equals(by, that.by) &&
Objects.equals(forValue, that.forValue) &&
Objects.equals(host, that.host) &&
Objects.equals(proto, that.proto) &&
extensions.equals(that.extensions);
}
@Override
public int hashCode() {
return Objects.hash(by, forValue, host, proto, extensions);
}
}