caddyhttp: Add split_path to file matcher (used by php_fastcgi) (#3302)

* matcher: Add `split_path` option to file matcher; used in php_fastcgi

* matcher: Skip try_files split if not the final part of the filename

* matcher: Add MatchFile tests

* matcher: Clarify SplitPath godoc

8 files changed, 158 insertions, 4 deletions

diff --git a/modules/caddyhttp/fileserver/matcher.go b/modules/caddyhttp/fileserver/matcher.go
index 1915fb7..1beb8ba 100644
--- a/modules/caddyhttp/fileserver/matcher.go
+++ b/modules/caddyhttp/fileserver/matcher.go
@@ -68,6 +68,17 @@ type MatchFile struct {
 	//
 	// Default is first_exist.
 	TryPolicy string `json:"try_policy,omitempty"`
+
+	// A list of delimiters to use to split the path in two
+	// when trying files. If empty, no splitting will
+	// occur, and the path will be tried as-is. For each
+	// split value, the left-hand side of the split,
+	// including the split value, will be the path tried.
+	// For example, the path `/remote.php/dav/` using the
+	// split value `.php` would try the file `/remote.php`.
+	// Each delimiter must appear at the end of a URI path
+	// component in order to be used as a split delimiter.
+	SplitPath []string `json:"split_path,omitempty"`
 }
 
 // CaddyModule returns the Caddy module information.
@@ -105,6 +116,11 @@ func (m *MatchFile) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 					return d.ArgErr()
 				}
 				m.TryPolicy = d.Val()
+			case "split":
+				m.SplitPath = d.RemainingArgs()
+				if len(m.SplitPath) == 0 {
+					return d.ArgErr()
+				}
 			}
 		}
 	}
@@ -167,7 +183,7 @@ func (m MatchFile) selectFile(r *http.Request) (rel, abs string, matched bool) {
 	switch m.TryPolicy {
 	case "", tryPolicyFirstExist:
 		for _, f := range m.TryFiles {
-			suffix := path.Clean(repl.ReplaceAll(f, ""))
+			suffix := m.firstSplit(path.Clean(repl.ReplaceAll(f, "")))
 			fullpath := sanitizedPathJoin(root, suffix)
 			if strictFileExists(fullpath) {
 				return suffix, fullpath, true
@@ -179,7 +195,7 @@ func (m MatchFile) selectFile(r *http.Request) (rel, abs string, matched bool) {
 		var largestFilename string
 		var largestSuffix string
 		for _, f := range m.TryFiles {
-			suffix := path.Clean(repl.ReplaceAll(f, ""))
+			suffix := m.firstSplit(path.Clean(repl.ReplaceAll(f, "")))
 			fullpath := sanitizedPathJoin(root, suffix)
 			info, err := os.Stat(fullpath)
 			if err == nil && info.Size() > largestSize {
@@ -195,7 +211,7 @@ func (m MatchFile) selectFile(r *http.Request) (rel, abs string, matched bool) {
 		var smallestFilename string
 		var smallestSuffix string
 		for _, f := range m.TryFiles {
-			suffix := path.Clean(repl.ReplaceAll(f, ""))
+			suffix := m.firstSplit(path.Clean(repl.ReplaceAll(f, "")))
 			fullpath := sanitizedPathJoin(root, suffix)
 			info, err := os.Stat(fullpath)
 			if err == nil && (smallestSize == 0 || info.Size() < smallestSize) {
@@ -211,7 +227,7 @@ func (m MatchFile) selectFile(r *http.Request) (rel, abs string, matched bool) {
 		var recentFilename string
 		var recentSuffix string
 		for _, f := range m.TryFiles {
-			suffix := path.Clean(repl.ReplaceAll(f, ""))
+			suffix := m.firstSplit(path.Clean(repl.ReplaceAll(f, "")))
 			fullpath := sanitizedPathJoin(root, suffix)
 			info, err := os.Stat(fullpath)
 			if err == nil &&
@@ -256,6 +272,26 @@ func strictFileExists(file string) bool {
 	return !stat.IsDir()
 }
 
+// firstSplit returns the first result where the path
+// can be split in two by a value in m.SplitPath. The
+// result is the first piece of the path that ends with
+// in the split value. Returns the path as-is if the
+// path cannot be split.
+func (m MatchFile) firstSplit(path string) string {
+	lowerPath := strings.ToLower(path)
+	for _, split := range m.SplitPath {
+		if idx := strings.Index(lowerPath, strings.ToLower(split)); idx > -1 {
+			pos := idx + len(split)
+			// skip the split if it's not the final part of the filename
+			if pos != len(path) && !strings.HasPrefix(path[pos:], "/") {
+				continue
+			}
+			return path[:pos]
+		}
+	}
+	return path
+}
+
 const (
 	tryPolicyFirstExist      = "first_exist"
 	tryPolicyLargestSize     = "largest_size"
diff --git a/modules/caddyhttp/fileserver/matcher_test.go b/modules/caddyhttp/fileserver/matcher_test.go
new file mode 100644
index 0000000..aa84900
--- /dev/null
+++ b/modules/caddyhttp/fileserver/matcher_test.go
@@ -0,0 +1,102 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// 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 fileserver
+
+import (
+	"net/http"
+	"net/url"
+	"testing"
+
+	"github.com/caddyserver/caddy/v2/modules/caddyhttp"
+)
+
+func TestPhpFileMatcher(t *testing.T) {
+
+	for i, tc := range []struct {
+		path string
+		expectedPath string
+		matched bool
+	}{
+		{
+			path: "/index.php",
+			expectedPath: "/index.php",
+			matched: true,
+		},
+		{
+			path: "/index.php/somewhere",
+			expectedPath: "/index.php",
+			matched: true,
+		},
+		{
+			path: "/remote.php",
+			expectedPath: "/remote.php",
+			matched: true,
+		},
+		{
+			path: "/remote.php/somewhere",
+			expectedPath: "/remote.php",
+			matched: true,
+		},
+		{
+			path: "/missingfile.php",
+			matched: false,
+		},
+		{
+			path: "/notphp.php.txt",
+			expectedPath: "/notphp.php.txt",
+			matched: true,
+		},
+		{
+			path: "/notphp.php.txt/",
+			expectedPath: "/notphp.php.txt",
+			matched: true,
+		},
+		{
+			path: "/notphp.php.txt.suffixed",
+			matched: false,
+		},
+		{
+			path: "/foo.php.php/index.php",
+			expectedPath: "/foo.php.php/index.php",
+			matched: true,
+		},
+	} {
+		m := &MatchFile{
+			Root:      "./testdata",
+			TryFiles:  []string{"{http.request.uri.path}"},
+			SplitPath: []string{".php"},
+		}
+
+		req := &http.Request{URL: &url.URL{Path: tc.path}}
+		repl := caddyhttp.NewTestReplacer(req)
+
+		result := m.Match(req)
+		if result != tc.matched {
+			t.Fatalf("Test %d: match bool result: %v, expected: %v", i, result, tc.matched)
+		}
+
+		rel, ok := repl.Get("http.matchers.file.relative")
+		if !ok && result {
+			t.Fatalf("Test %d: expected replacer value", i)
+		}
+		if !result {
+			continue
+		}
+
+		if rel != tc.expectedPath {
+			t.Fatalf("Test %d: actual path: %v, expected: %v", i, rel, tc.expectedPath)
+		}
+	}
+}
\ No newline at end of file
diff --git a/modules/caddyhttp/fileserver/testdata/foo.php.php/index.php b/modules/caddyhttp/fileserver/testdata/foo.php.php/index.php
new file mode 100644
index 0000000..4a2ac6b
--- /dev/null
+++ b/modules/caddyhttp/fileserver/testdata/foo.php.php/index.php
@@ -0,0 +1 @@
+foo.php.php/index.php
diff --git a/modules/caddyhttp/fileserver/testdata/index.php b/modules/caddyhttp/fileserver/testdata/index.php
new file mode 100644
index 0000000..0012f7d
--- /dev/null
+++ b/modules/caddyhttp/fileserver/testdata/index.php
@@ -0,0 +1 @@
+index.php
\ No newline at end of file
diff --git a/modules/caddyhttp/fileserver/testdata/notphp.php.txt b/modules/caddyhttp/fileserver/testdata/notphp.php.txt
new file mode 100644
index 0000000..eba1876
--- /dev/null
+++ b/modules/caddyhttp/fileserver/testdata/notphp.php.txt
@@ -0,0 +1 @@
+notphp.php.txt
diff --git a/modules/caddyhttp/fileserver/testdata/remote.php b/modules/caddyhttp/fileserver/testdata/remote.php
new file mode 100644
index 0000000..78f06a2
--- /dev/null
+++ b/modules/caddyhttp/fileserver/testdata/remote.php
@@ -0,0 +1 @@
+remote.php
\ No newline at end of file
diff --git a/modules/caddyhttp/replacer.go b/modules/caddyhttp/replacer.go
index b83977c..670b2e3 100644
--- a/modules/caddyhttp/replacer.go
+++ b/modules/caddyhttp/replacer.go
@@ -15,6 +15,7 @@
 package caddyhttp
 
 import (
+	"context"
 	"crypto/sha256"
 	"crypto/tls"
 	"crypto/x509"
@@ -30,6 +31,16 @@ import (
 	"github.com/caddyserver/caddy/v2/modules/caddytls"
 )
 
+// NewTestReplacer creates a replacer for an http.Request
+// for use in tests that are not in this package
+func NewTestReplacer(req *http.Request) *caddy.Replacer {
+	repl := caddy.NewReplacer()
+	ctx := context.WithValue(req.Context(), caddy.ReplacerCtxKey, repl)
+	*req = *req.WithContext(ctx)
+	addHTTPVarsToReplacer(repl, req, nil)
+	return repl
+}
+
 func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.ResponseWriter) {
 	httpVars := func(key string) (interface{}, bool) {
 		if req != nil {
diff --git a/modules/caddyhttp/reverseproxy/fastcgi/caddyfile.go b/modules/caddyhttp/reverseproxy/fastcgi/caddyfile.go
index 8924a6d..8a5e27e 100644
--- a/modules/caddyhttp/reverseproxy/fastcgi/caddyfile.go
+++ b/modules/caddyhttp/reverseproxy/fastcgi/caddyfile.go
@@ -149,6 +149,7 @@ func parsePHPFastCGI(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error
 	rewriteMatcherSet := caddy.ModuleMap{
 		"file": h.JSON(fileserver.MatchFile{
 			TryFiles: []string{"{http.request.uri.path}", "{http.request.uri.path}/index.php", "index.php"},
+			SplitPath: []string{".php"},
 		}),
 	}
 	rewriteHandler := rewrite.Rewrite{