Java tutorial
/** * Copyright 2016 Pratapi Hemant Patel * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ package com.github.sip; import java.util.List; import java.util.Objects; import org.antlr.v4.runtime.ANTLRInputStream; import org.antlr.v4.runtime.BailErrorStrategy; import org.antlr.v4.runtime.CommonTokenStream; import org.antlr.v4.runtime.tree.TerminalNode; import antlr4.SipLexer; import antlr4.SipParser; import antlr4.SipParser.CoreUriContext; import antlr4.SipParser.HostPortContext; import antlr4.SipParser.SipUriContext; import antlr4.SipParser.SipsUriContext; import antlr4.UriHeadersLexer; import antlr4.UriHeadersParser; import antlr4.UriHeadersParser.HeaderContext; import antlr4.UriHeadersParser.UriHeadersContext; import antlr4.UriHeadersParser.UriParameterContext; public class SipUtils { /** * Method to parse a sip uri to return its details in a more user friendly * way. For example a sip uri is of the form * * <pre> * sip:hemant@abc.com:80;uriParam1=uriValue1;uriParam2?headerKey=headerValue * </pre> * * This method will parse the individual details of sip uri such as * userInfo("hemant"), host("abc.com"), port(80), map of uri parameters and * headers. * * The grammar used to parse sip uri as per the * https://www.ietf.org/rfc/rfc3261.txt with some minor exception to * simplify parsing. * * @see SipUriInfo * * @param sipUri * string representing a sip uri to be parsed. * @return an object of {@link SipUriInfo} class containing sip uri details * @throws IllegalStateException * in case an invalid sip uri provided */ public static SipUriInfo parseSipUri(String sipUri) throws IllegalStateException { SipUriContext sipUriContext = getSipParser(sipUri).sipUri(); CoreUriContext coreUriContext = sipUriContext.coreUri(); SipUriInfo info = new SipUriInfo(); parseCoreUri(coreUriContext, sipUri, info); return info; } /** * Similar to {@link #parseSipUri(String)} with one difference, its a sips * uri. * * <pre> * sip:hemant@abc.com:80;uriParam1=uriValue1;uriParam2?headerKey=headerValue * </pre> * * @param sipsUri * string representing a sip uri to be parsed. * @return an object of {@link SipUriInfo} class containing sip uri details * @throws IllegalStateException * in case an invalid sip uri provided */ public static SipUriInfo parseSipsUri(String sipsUri) throws IllegalStateException { SipsUriContext sipUriContext = getSipParser(sipsUri).sipsUri(); CoreUriContext coreUriContext = sipUriContext.coreUri(); SipUriInfo info = new SipUriInfo().setSips(true); parseCoreUri(coreUriContext, sipsUri, info); return info; } private static void parseCoreUri(CoreUriContext coreUriContext, String input, SipUriInfo info) { TerminalNode userInfo = coreUriContext.USER_INFO(); // userInfo is an optional field need to check for null if (Objects.nonNull(userInfo)) { // removing last char '@' StringBuilder builder = new StringBuilder(userInfo.getText()); builder.deleteCharAt(builder.length() - 1); info.setUserInfo(builder.toString()); } HostPortContext hostPortContext = coreUriContext.hostPort(); info.setHost(hostPortContext.HOST().getText()); TerminalNode port = hostPortContext.PORT(); if (Objects.nonNull(port)) { // first char is ':', removing it before converting to integer info.setPort(Integer.parseInt(port.getText().substring(1))); } int parsedLength = coreUriContext.getStop().getStopIndex(); if (parsedLength < input.length() - 1) { parseUriHeaders(input.substring(parsedLength + 1), info, parsedLength); } } private static void parseUriHeaders(String input, SipUriInfo info, int parsedLength) { UriHeadersContext uriHeadersContext = getUriHeadersParser(input, parsedLength).uriHeaders(); parserUriParameters(uriHeadersContext.uriParameters().uriParameter(), info); // header field is optional may be not present if (Objects.nonNull(uriHeadersContext.headers())) { parseHeaders(uriHeadersContext.headers().header(), info); } } private static void parserUriParameters(List<UriParameterContext> uriParameterContexts, SipUriInfo info) { uriParameterContexts.forEach(e -> { // this list has max element count two, one key and other value // min is one because key is mandatory, value is optional List<TerminalNode> paramKeyValues = e.NAME_OR_VALUE(); String paramKey = paramKeyValues.get(0).getText(); String paramValue = null; // in case value present if (paramKeyValues.size() == 2) { paramValue = paramKeyValues.get(1).getText(); } info.addUriParameters(paramKey, paramValue); }); } private static void parseHeaders(List<HeaderContext> headerContexts, SipUriInfo info) { headerContexts.forEach(e -> { // this list has element count two, one key and other value List<TerminalNode> headerKeyValues = e.NAME_OR_VALUE(); info.addHeaders(headerKeyValues.get(0).getText(), headerKeyValues.get(1).getText()); }); } private static SipParser getSipParser(String input) { SipErrorListener listener = new SipErrorListener(); // Get our lexer SipLexer lexer = new SipLexer(new ANTLRInputStream(input)); lexer.addErrorListener(listener); // Get a list of matched tokens CommonTokenStream tokens = new CommonTokenStream(lexer); // Pass the tokens to the parser SipParser parser = new SipParser(tokens); parser.setErrorHandler(new BailErrorStrategy()); parser.addErrorListener(listener); return parser; } private static UriHeadersParser getUriHeadersParser(String input, int parsedLength) { SipErrorListener listener = new SipErrorListener(parsedLength); // Get our lexer UriHeadersLexer lexer = new UriHeadersLexer(new ANTLRInputStream(input)); lexer.addErrorListener(listener); // Get a list of matched tokens CommonTokenStream tokens = new CommonTokenStream(lexer); // Pass the tokens to the parser UriHeadersParser parser = new UriHeadersParser(tokens); parser.addErrorListener(listener); return parser; } }