src/main/java/com/ericsson/gerrit/plugins/goimport/GoImportFilter.java - plugins/go-import - Git at Google

 // Copyright (C) 2017 The Android Open Source Project
 //
 // 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.ericsson.gerrit.plugins.goimport;

 import com.google.common.base.Strings;
 import com.google.gerrit.httpd.AllRequestFilter;
 import com.google.gerrit.httpd.HtmlDomUtil;
 import com.google.gerrit.reviewdb.client.BranchNameKey;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.server.AnonymousUser;
 import com.google.gerrit.server.config.CanonicalWebUrl;
 import com.google.gerrit.server.permissions.PermissionBackend;
 import com.google.gerrit.server.permissions.RefPermission;
 import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.util.http.CacheHeaders;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.Singleton;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import javax.servlet.FilterChain;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 @Singleton
 public class GoImportFilter extends AllRequestFilter {

   private static final String PAGE_404 =
       "<!DOCTYPE html>\n"
           + "<html>\n"
           + "<head>\n"
           + "  <title>Gerrit-Go-Import</title>\n"
           + "  <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"/>\n"
           + "</head>\n"
           + "<body>\n"
           + "NOT FOUND\n"
           + "</body>\n"
           + "</html>";

   private static final String PAGE_200 =
       "<!DOCTYPE html>\n"
           + "<html>\n"
           + "<head>\n"
           + "  <title>Gerrit-Go-Import</title>\n"
           + "  <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"/>\n"
           + "  <meta name=\"go-import\" content=\"${content}\"/>\n"
           + "</head>\n"
           + "<body>\n"
           + "<div>\n"
           + "  Gerrit-Go-Import\n"
           + "</div>\n"
           + "</body>\n"
           + "</html>";

   private final Provider<AnonymousUser> anonProvider;
   private final PermissionBackend permissions;
   private final ProjectCache projectCache;
   final String webUrl;
   final String projectPrefix;

   @Inject
   GoImportFilter(
       Provider<AnonymousUser> anonProvider,
       PermissionBackend permissions,
       ProjectCache projectCache,
       @CanonicalWebUrl String webUrl)
       throws URISyntaxException {
     this.anonProvider = anonProvider;
     this.permissions = permissions;
     this.projectCache = projectCache;
     this.webUrl = webUrl.replaceFirst("/?$", "/");
     this.projectPrefix = generateProjectPrefix();
   }

   private String generateProjectPrefix() throws URISyntaxException {
     URI uri = new URI(webUrl);
     return uri.getHost() + (uri.getPort() == -1 ? "" : ":" + uri.getPort()) + uri.getPath();
   }

   @Override
   public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
       throws IOException, ServletException {
     if (request instanceof HttpServletRequest) {
       HttpServletRequest req = (HttpServletRequest) request;
       HttpServletResponse rsp = (HttpServletResponse) response;
       String servletPath = req.getServletPath();
       if ("1".equals(req.getParameter("go-get"))) {
         // Because Gerrit allows for arbitrary-depth project names
         // (that is, both "a" and "a/b/c" are both legal), we are going
         // to find the most specific such project that matches the path.
         //
         // For example, assume that we have the following projects:
         //    a
         //    a/b
         // 1. If the requested path is "a", then project "a" would be chosen.
         // 2. If the requested path is "a/b", then project "a/b" would be chosen.
         // 3. If the requested path is "a/c", then project "a" would be chosen.
         // 4. If the requested path is "a/b/c/d", then project "a/b" would be chosen.
         // 5. If the requested path is "x/y/z", then this will fail with a 404 error.
         String existent = getLongestMatch(getProjectName(servletPath));
         byte[] toSend = PAGE_404.getBytes();
         rsp.setStatus(404);
         if (!Strings.isNullOrEmpty(existent)) {
           toSend = PAGE_200.replace("${content}", getContent(existent)).getBytes();
           rsp.setStatus(200);
         }
         CacheHeaders.setNotCacheable(rsp);
         rsp.setContentType("text/html");
         rsp.setCharacterEncoding(HtmlDomUtil.ENC.name());
         rsp.setContentLength(toSend.length);
         try (OutputStream out = rsp.getOutputStream()) {
           out.write(toSend);
         }
       } else {
         chain.doFilter(request, response);
       }
     } else {
       chain.doFilter(request, response);
     }
   }

   private String getLongestMatch(String projectName) {
     Path projectPath = Paths.get(projectName);
     while (projectPath.getNameCount() >= 1) {
       String asString = projectPath.toString();
       if (projectExists(asString)) {
         return asString;
       }
       projectPath = projectPath.getParent();
       if (projectPath == null) {
         break;
       }
     }
     return null;
   }

   private String getProjectName(String servletPath) {
     return servletPath.replaceFirst("/", "");
   }

   private CharSequence getContent(String projectName) {
     return projectPrefix + projectName + " git " + getRepoRoot(projectName);
   }

   private String getRepoRoot(String projectName) {
     if (allowsAnonymousAccess(projectName)) {
       return webUrl + projectName;
     }

     return webUrl + "a/" + projectName;
   }

   private boolean allowsAnonymousAccess(String projectName) {
     AnonymousUser anonymous = anonProvider.get();
     BranchNameKey heads = BranchNameKey.create(Project.nameKey(projectName), RefNames.REFS_HEADS);

     return permissions.user(anonymous).ref(heads).testOrFalse(RefPermission.READ);
   }

   private boolean projectExists(String projectName) {
     ProjectState p = projectCache.get(Project.nameKey(projectName));
     return p != null;
   }
 }
	// Copyright (C) 2017 The Android Open Source Project
	//
	// 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.ericsson.gerrit.plugins.goimport;

	import com.google.common.base.Strings;
	import com.google.gerrit.httpd.AllRequestFilter;
	import com.google.gerrit.httpd.HtmlDomUtil;
	import com.google.gerrit.reviewdb.client.BranchNameKey;
	import com.google.gerrit.reviewdb.client.Project;
	import com.google.gerrit.reviewdb.client.RefNames;
	import com.google.gerrit.server.AnonymousUser;
	import com.google.gerrit.server.config.CanonicalWebUrl;
	import com.google.gerrit.server.permissions.PermissionBackend;
	import com.google.gerrit.server.permissions.RefPermission;
	import com.google.gerrit.server.project.ProjectCache;
	import com.google.gerrit.server.project.ProjectState;
	import com.google.gerrit.util.http.CacheHeaders;
	import com.google.inject.Inject;
	import com.google.inject.Provider;
	import com.google.inject.Singleton;
	import java.io.IOException;
	import java.io.OutputStream;
	import java.net.URI;
	import java.net.URISyntaxException;
	import java.nio.file.Path;
	import java.nio.file.Paths;
	import javax.servlet.FilterChain;
	import javax.servlet.ServletException;
	import javax.servlet.ServletRequest;
	import javax.servlet.ServletResponse;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;

	@Singleton
	public class GoImportFilter extends AllRequestFilter {

	private static final String PAGE_404 =
	"<!DOCTYPE html>\n"
	+ "<html>\n"
	+ "<head>\n"
	+ " <title>Gerrit-Go-Import</title>\n"
	+ " <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"/>\n"
	+ "</head>\n"
	+ "<body>\n"
	+ "NOT FOUND\n"
	+ "</body>\n"
	+ "</html>";

	private static final String PAGE_200 =
	"<!DOCTYPE html>\n"
	+ "<html>\n"
	+ "<head>\n"
	+ " <title>Gerrit-Go-Import</title>\n"
	+ " <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\"/>\n"
	+ " <meta name=\"go-import\" content=\"${content}\"/>\n"
	+ "</head>\n"
	+ "<body>\n"
	+ "<div>\n"
	+ " Gerrit-Go-Import\n"
	+ "</div>\n"
	+ "</body>\n"
	+ "</html>";

	private final Provider<AnonymousUser> anonProvider;
	private final PermissionBackend permissions;
	private final ProjectCache projectCache;
	final String webUrl;
	final String projectPrefix;

	@Inject
	GoImportFilter(
	Provider<AnonymousUser> anonProvider,
	PermissionBackend permissions,
	ProjectCache projectCache,
	@CanonicalWebUrl String webUrl)
	throws URISyntaxException {
	this.anonProvider = anonProvider;
	this.permissions = permissions;
	this.projectCache = projectCache;
	this.webUrl = webUrl.replaceFirst("/?$", "/");
	this.projectPrefix = generateProjectPrefix();
	}

	private String generateProjectPrefix() throws URISyntaxException {
	URI uri = new URI(webUrl);
	return uri.getHost() + (uri.getPort() == -1 ? "" : ":" + uri.getPort()) + uri.getPath();
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
	throws IOException, ServletException {
	if (request instanceof HttpServletRequest) {
	HttpServletRequest req = (HttpServletRequest) request;
	HttpServletResponse rsp = (HttpServletResponse) response;
	String servletPath = req.getServletPath();
	if ("1".equals(req.getParameter("go-get"))) {
	// Because Gerrit allows for arbitrary-depth project names
	// (that is, both "a" and "a/b/c" are both legal), we are going
	// to find the most specific such project that matches the path.
	//
	// For example, assume that we have the following projects:
	// a
	// a/b
	// 1. If the requested path is "a", then project "a" would be chosen.
	// 2. If the requested path is "a/b", then project "a/b" would be chosen.
	// 3. If the requested path is "a/c", then project "a" would be chosen.
	// 4. If the requested path is "a/b/c/d", then project "a/b" would be chosen.
	// 5. If the requested path is "x/y/z", then this will fail with a 404 error.
	String existent = getLongestMatch(getProjectName(servletPath));
	byte[] toSend = PAGE_404.getBytes();
	rsp.setStatus(404);
	if (!Strings.isNullOrEmpty(existent)) {
	toSend = PAGE_200.replace("${content}", getContent(existent)).getBytes();
	rsp.setStatus(200);
	}
	CacheHeaders.setNotCacheable(rsp);
	rsp.setContentType("text/html");
	rsp.setCharacterEncoding(HtmlDomUtil.ENC.name());
	rsp.setContentLength(toSend.length);
	try (OutputStream out = rsp.getOutputStream()) {
	out.write(toSend);
	}
	} else {
	chain.doFilter(request, response);
	}
	} else {
	chain.doFilter(request, response);
	}
	}

	private String getLongestMatch(String projectName) {
	Path projectPath = Paths.get(projectName);
	while (projectPath.getNameCount() >= 1) {
	String asString = projectPath.toString();
	if (projectExists(asString)) {
	return asString;
	}
	projectPath = projectPath.getParent();
	if (projectPath == null) {
	break;
	}
	}
	return null;
	}

	private String getProjectName(String servletPath) {
	return servletPath.replaceFirst("/", "");
	}

	private CharSequence getContent(String projectName) {
	return projectPrefix + projectName + " git " + getRepoRoot(projectName);
	}

	private String getRepoRoot(String projectName) {
	if (allowsAnonymousAccess(projectName)) {
	return webUrl + projectName;
	}

	return webUrl + "a/" + projectName;
	}

	private boolean allowsAnonymousAccess(String projectName) {
	AnonymousUser anonymous = anonProvider.get();
	BranchNameKey heads = BranchNameKey.create(Project.nameKey(projectName), RefNames.REFS_HEADS);

	return permissions.user(anonymous).ref(heads).testOrFalse(RefPermission.READ);
	}

	private boolean projectExists(String projectName) {
	ProjectState p = projectCache.get(Project.nameKey(projectName));
	return p != null;
	}
	}