Expose several Caddy HTTP Matchers to the CEL Matcher (#4715)

Co-authored-by: Francis Lavoie <lavofr@gmail.com>

1 files changed, 289 insertions, 1 deletions

diff --git a/modules/caddyhttp/matchers.go b/modules/caddyhttp/matchers.go
index f8953ef..268b936 100644
--- a/modules/caddyhttp/matchers.go
+++ b/modules/caddyhttp/matchers.go
@@ -16,6 +16,7 @@ package caddyhttp
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -23,6 +24,7 @@ import (
 	"net/url"
 	"path"
 	"path/filepath"
+	"reflect"
 	"regexp"
 	"sort"
 	"strconv"
@@ -30,7 +32,12 @@ import (
 
 	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
+	"github.com/google/cel-go/cel"
+	"github.com/google/cel-go/checker/decls"
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
 	"go.uber.org/zap"
+	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
 )
 
 type (
@@ -291,6 +298,29 @@ outer:
 	return false
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression host('localhost')
+func (MatchHost) CELLibrary(ctx caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		"host",
+		"host_match_request_list",
+		[]*exprpb.Type{CelTypeListString},
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			strList, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+			matcher := MatchHost(strList.([]string))
+			err = matcher.Provision(ctx)
+			return matcher, err
+		},
+	)
+}
+
 // fuzzy returns true if the given hostname h is not a specific
 // hostname, e.g. has placeholders or wildcards.
 func (MatchHost) fuzzy(h string) bool { return strings.ContainsAny(h, "{*") }
@@ -396,6 +426,33 @@ func (m MatchPath) Match(r *http.Request) bool {
 	return false
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression path('*substring*', '*suffix')
+func (MatchPath) CELLibrary(ctx caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		// name of the macro, this is the function name that users see when writing expressions.
+		"path",
+		// name of the function that the macro will be rewritten to call.
+		"path_match_request_list",
+		// internal data type of the MatchPath value.
+		[]*exprpb.Type{CelTypeListString},
+		// function to convert a constant list of strings to a MatchPath instance.
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			strList, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+			matcher := MatchPath(strList.([]string))
+			err = matcher.Provision(ctx)
+			return matcher, err
+		},
+	)
+}
+
 // UnmarshalCaddyfile implements caddyfile.Unmarshaler.
 func (m *MatchPath) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	for d.Next() {
@@ -440,6 +497,50 @@ func (m MatchPathRE) Match(r *http.Request) bool {
 	return m.MatchRegexp.Match(cleanedPath, repl)
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression path_regexp('^/bar')
+func (MatchPathRE) CELLibrary(ctx caddy.Context) (cel.Library, error) {
+	unnamedPattern, err := CELMatcherImpl(
+		"path_regexp",
+		"path_regexp_request_string",
+		[]*exprpb.Type{decls.String},
+		func(data ref.Val) (RequestMatcher, error) {
+			pattern := data.(types.String)
+			matcher := MatchPathRE{MatchRegexp{Pattern: string(pattern)}}
+			err := matcher.Provision(ctx)
+			return matcher, err
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+	namedPattern, err := CELMatcherImpl(
+		"path_regexp",
+		"path_regexp_request_string_string",
+		[]*exprpb.Type{decls.String, decls.String},
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			params, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+			strParams := params.([]string)
+			matcher := MatchPathRE{MatchRegexp{Name: strParams[0], Pattern: strParams[1]}}
+			err = matcher.Provision(ctx)
+			return matcher, err
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+	envOpts := append(unnamedPattern.CompileOptions(), namedPattern.CompileOptions()...)
+	prgOpts := append(unnamedPattern.ProgramOptions(), namedPattern.ProgramOptions()...)
+	return NewMatcherCELLibrary(envOpts, prgOpts), nil
+}
+
 // CaddyModule returns the Caddy module information.
 func (MatchMethod) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
@@ -469,6 +570,27 @@ func (m MatchMethod) Match(r *http.Request) bool {
 	return false
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression method('PUT', 'POST')
+func (MatchMethod) CELLibrary(_ caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		"method",
+		"method_request_list",
+		[]*exprpb.Type{CelTypeListString},
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			strList, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+			return MatchMethod(strList.([]string)), nil
+		},
+	)
+}
+
 // CaddyModule returns the Caddy module information.
 func (MatchQuery) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
@@ -518,6 +640,26 @@ func (m MatchQuery) Match(r *http.Request) bool {
 	return len(m) == 0 && len(r.URL.Query()) == 0
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression query({'sort': 'asc'}) || query({'foo': ['*bar*', 'baz']})
+func (MatchQuery) CELLibrary(_ caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		"query",
+		"query_matcher_request_map",
+		[]*exprpb.Type{CelTypeJson},
+		func(data ref.Val) (RequestMatcher, error) {
+			mapStrListStr, err := CELValueToMapStrList(data)
+			if err != nil {
+				return nil, err
+			}
+			return MatchQuery(url.Values(mapStrListStr)), nil
+		},
+	)
+}
+
 // CaddyModule returns the Caddy module information.
 func (MatchHeader) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
@@ -573,6 +715,27 @@ func (m MatchHeader) Match(r *http.Request) bool {
 	return matchHeaders(r.Header, http.Header(m), r.Host, repl)
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression header({'content-type': 'image/png'})
+//    expression header({'foo': ['bar', 'baz']}) // match bar or baz
+func (MatchHeader) CELLibrary(_ caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		"header",
+		"header_matcher_request_map",
+		[]*exprpb.Type{CelTypeJson},
+		func(data ref.Val) (RequestMatcher, error) {
+			mapStrListStr, err := CELValueToMapStrList(data)
+			if err != nil {
+				return nil, err
+			}
+			return MatchHeader(http.Header(mapStrListStr)), nil
+		},
+	)
+}
+
 // getHeaderFieldVals returns the field values for the given fieldName from input.
 // The host parameter should be obtained from the http.Request.Host field since
 // net/http removes it from the header map.
@@ -710,6 +873,57 @@ func (m MatchHeaderRE) Validate() error {
 	return nil
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression header_regexp('foo', 'Field', 'fo+')
+func (MatchHeaderRE) CELLibrary(ctx caddy.Context) (cel.Library, error) {
+	unnamedPattern, err := CELMatcherImpl(
+		"header_regexp",
+		"header_regexp_request_string_string",
+		[]*exprpb.Type{decls.String, decls.String},
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			params, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+			strParams := params.([]string)
+			matcher := MatchHeaderRE{}
+			matcher[strParams[0]] = &MatchRegexp{Pattern: strParams[1], Name: ""}
+			err = matcher.Provision(ctx)
+			return matcher, err
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+	namedPattern, err := CELMatcherImpl(
+		"header_regexp",
+		"header_regexp_request_string_string_string",
+		[]*exprpb.Type{decls.String, decls.String, decls.String},
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			params, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+			strParams := params.([]string)
+			matcher := MatchHeaderRE{}
+			matcher[strParams[1]] = &MatchRegexp{Pattern: strParams[2], Name: strParams[0]}
+			err = matcher.Provision(ctx)
+			return matcher, err
+		},
+	)
+	if err != nil {
+		return nil, err
+	}
+	envOpts := append(unnamedPattern.CompileOptions(), namedPattern.CompileOptions()...)
+	prgOpts := append(unnamedPattern.ProgramOptions(), namedPattern.ProgramOptions()...)
+	return NewMatcherCELLibrary(envOpts, prgOpts), nil
+}
+
 // CaddyModule returns the Caddy module information.
 func (MatchProtocol) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
@@ -743,6 +957,26 @@ func (m *MatchProtocol) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	return nil
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression protocol('https')
+func (MatchProtocol) CELLibrary(_ caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		"protocol",
+		"protocol_request_string",
+		[]*exprpb.Type{decls.String},
+		func(data ref.Val) (RequestMatcher, error) {
+			protocolStr, ok := data.(types.String)
+			if !ok {
+				return nil, errors.New("protocol argument was not a string")
+			}
+			return MatchProtocol(strings.ToLower(string(protocolStr))), nil
+		},
+	)
+}
+
 // CaddyModule returns the Caddy module information.
 func (MatchNot) CaddyModule() caddy.ModuleInfo {
 	return caddy.ModuleInfo{
@@ -887,6 +1121,46 @@ func (m *MatchRemoteIP) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	return nil
 }
 
+// CELLibrary produces options that expose this matcher for use in CEL
+// expression matchers.
+//
+// Example:
+//    expression remote_ip('forwarded', '192.168.0.0/16', '172.16.0.0/12', '10.0.0.0/8')
+func (MatchRemoteIP) CELLibrary(ctx caddy.Context) (cel.Library, error) {
+	return CELMatcherImpl(
+		// name of the macro, this is the function name that users see when writing expressions.
+		"remote_ip",
+		// name of the function that the macro will be rewritten to call.
+		"remote_ip_match_request_list",
+		// internal data type of the MatchPath value.
+		[]*exprpb.Type{CelTypeListString},
+		// function to convert a constant list of strings to a MatchPath instance.
+		func(data ref.Val) (RequestMatcher, error) {
+			refStringList := reflect.TypeOf([]string{})
+			strList, err := data.ConvertToNative(refStringList)
+			if err != nil {
+				return nil, err
+			}
+
+			m := MatchRemoteIP{}
+
+			for _, input := range strList.([]string) {
+				if input == "forwarded" {
+					if len(m.Ranges) > 0 {
+						return nil, errors.New("if used, 'forwarded' must be first argument")
+					}
+					m.Forwarded = true
+					continue
+				}
+				m.Ranges = append(m.Ranges, input)
+			}
+
+			err = m.Provision(ctx)
+			return m, err
+		},
+	)
+}
+
 // Provision parses m's IP ranges, either from IP or CIDR expressions.
 func (m *MatchRemoteIP) Provision(ctx caddy.Context) error {
 	m.logger = ctx.Logger(m)
@@ -1062,7 +1336,9 @@ func (mre *MatchRegexp) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	return nil
 }
 
-var wordRE = regexp.MustCompile(`\w+`)
+var (
+	wordRE = regexp.MustCompile(`\w+`)
+)
 
 const regexpPlaceholderPrefix = "http.regexp"
 
@@ -1103,6 +1379,18 @@ var (
 	_ caddyfile.Unmarshaler = (*VarsMatcher)(nil)
 	_ caddyfile.Unmarshaler = (*MatchVarsRE)(nil)
 
+	_ CELLibraryProducer = (*MatchHost)(nil)
+	_ CELLibraryProducer = (*MatchPath)(nil)
+	_ CELLibraryProducer = (*MatchPathRE)(nil)
+	_ CELLibraryProducer = (*MatchMethod)(nil)
+	_ CELLibraryProducer = (*MatchQuery)(nil)
+	_ CELLibraryProducer = (*MatchHeader)(nil)
+	_ CELLibraryProducer = (*MatchHeaderRE)(nil)
+	_ CELLibraryProducer = (*MatchProtocol)(nil)
+	_ CELLibraryProducer = (*MatchRemoteIP)(nil)
+	// _ CELLibraryProducer = (*VarsMatcher)(nil)
+	// _ CELLibraryProducer = (*MatchVarsRE)(nil)
+
 	_ json.Marshaler   = (*MatchNot)(nil)
 	_ json.Unmarshaler = (*MatchNot)(nil)
 )