bouncer/internal/proxy/director/layer/rewriter/rules.go

package rewriter

import (
	"context"
	"net/http"

	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
	"forge.cadoles.com/cadoles/bouncer/internal/rule"
	ruleHTTP "forge.cadoles.com/cadoles/bouncer/internal/rule/http"
	"github.com/pkg/errors"
)

type RequestVars struct {
	Request     RequestVar `expr:"request"`
	OriginalURL URLVar     `expr:"original_url"`
}

type URLVar struct {
	Scheme      string  `expr:"scheme"`
	Opaque      string  `expr:"opaque"`
	User        UserVar `expr:"user"`
	Host        string  `expr:"host"`
	Path        string  `expr:"path"`
	RawPath     string  `expr:"raw_path"`
	RawQuery    string  `expr:"raw_query"`
	Fragment    string  `expr:"fragment"`
	RawFragment string  `expr:"raw_fragment"`
}

type UserVar struct {
	Username string `expr:"username"`
	Password string `expr:"password"`
}

type RequestVar struct {
	Method           string              `expr:"method"`
	URL              URLVar              `expr:"url"`
	RawURL           string              `expr:"raw_url"`
	Proto            string              `expr:"proto"`
	ProtoMajor       int                 `expr:"proto_major"`
	ProtoMinor       int                 `expr:"proto_minor"`
	Header           map[string][]string `expr:"header"`
	ContentLength    int64               `expr:"content_length"`
	TransferEncoding []string            `expr:"transfer_encoding"`
	Host             string              `expr:"host"`
	Trailer          map[string][]string `expr:"trailer"`
	RemoteAddr       string              `expr:"remote_addr"`
	RequestURI       string              `expr:"request_uri"`
}

func (l *Layer) applyRequestRules(ctx context.Context, r *http.Request, layerRevision int, options *LayerOptions) error {
	rules := options.Rules.Request
	if len(rules) == 0 {
		return nil
	}

	engine, err := l.getRequestRuleEngine(ctx, layerRevision, options)
	if err != nil {
		return errors.WithStack(err)
	}

	originalURL, err := director.OriginalURL(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	vars := &RequestVars{
		OriginalURL: URLVar{
			Scheme: originalURL.Scheme,
			Opaque: originalURL.Opaque,
			User: UserVar{
				Username: originalURL.User.Username(),
				Password: func() string {
					passwd, _ := originalURL.User.Password()
					return passwd
				}(),
			},
			Host:        originalURL.Host,
			Path:        originalURL.Path,
			RawPath:     originalURL.RawPath,
			RawQuery:    originalURL.RawQuery,
			Fragment:    originalURL.Fragment,
			RawFragment: originalURL.RawFragment,
		},
		Request: RequestVar{
			Method: r.Method,
			URL: URLVar{
				Scheme: r.URL.Scheme,
				Opaque: r.URL.Opaque,
				User: UserVar{
					Username: r.URL.User.Username(),
					Password: func() string {
						passwd, _ := r.URL.User.Password()
						return passwd
					}(),
				},
				Host:        r.URL.Host,
				Path:        r.URL.Path,
				RawPath:     r.URL.RawPath,
				RawQuery:    r.URL.RawQuery,
				Fragment:    r.URL.Fragment,
				RawFragment: r.URL.RawFragment,
			},
			RawURL:           r.URL.String(),
			Proto:            r.Proto,
			ProtoMajor:       r.ProtoMajor,
			ProtoMinor:       r.ProtoMinor,
			Header:           r.Header,
			ContentLength:    r.ContentLength,
			TransferEncoding: r.TransferEncoding,
			Host:             r.Host,
			Trailer:          r.Trailer,
			RemoteAddr:       r.RemoteAddr,
			RequestURI:       r.RequestURI,
		},
	}

	ctx = ruleHTTP.WithRequest(ctx, r)

	if _, err := engine.Apply(ctx, vars); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (l *Layer) getRequestRuleEngine(ctx context.Context, layerRevision int, options *LayerOptions) (*rule.Engine[*RequestVars], error) {
	engine, err := l.requestRuleEngine.Get(ctx, layerRevision, options)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return engine, nil
}

type ResponseVars struct {
	OriginalURL URLVar      `expr:"original_url"`
	Request     RequestVar  `expr:"request"`
	Response    ResponseVar `expr:"response"`
}

type ResponseVar struct {
	Status           string              `expr:"status"`
	StatusCode       int                 `expr:"status_code"`
	Proto            string              `expr:"proto"`
	ProtoMajor       int                 `expr:"proto_major"`
	ProtoMinor       int                 `expr:"proto_minor"`
	Header           map[string][]string `expr:"header"`
	ContentLength    int64               `expr:"content_length"`
	TransferEncoding []string            `expr:"transfer_encoding"`
	Uncompressed     bool                `expr:"uncompressed"`
	Trailer          map[string][]string `expr:"trailer"`
}

func (l *Layer) applyResponseRules(ctx context.Context, r *http.Response, layerRevision int, options *LayerOptions) error {
	rules := options.Rules.Response
	if len(rules) == 0 {
		return nil
	}

	engine, err := l.getResponseRuleEngine(ctx, layerRevision, options)
	if err != nil {
		return errors.WithStack(err)
	}

	originalURL, err := director.OriginalURL(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	vars := &ResponseVars{
		OriginalURL: URLVar{
			Scheme: originalURL.Scheme,
			Opaque: originalURL.Opaque,
			User: UserVar{
				Username: originalURL.User.Username(),
				Password: func() string {
					passwd, _ := originalURL.User.Password()
					return passwd
				}(),
			},
			Host:        originalURL.Host,
			Path:        originalURL.Path,
			RawPath:     originalURL.RawPath,
			RawQuery:    originalURL.RawQuery,
			Fragment:    originalURL.Fragment,
			RawFragment: originalURL.RawFragment,
		},
		Request: RequestVar{
			Method: r.Request.Method,
			URL: URLVar{
				Scheme: r.Request.URL.Scheme,
				Opaque: r.Request.URL.Opaque,
				User: UserVar{
					Username: r.Request.URL.User.Username(),
					Password: func() string {
						passwd, _ := r.Request.URL.User.Password()
						return passwd
					}(),
				},
				Host:        r.Request.URL.Host,
				Path:        r.Request.URL.Path,
				RawPath:     r.Request.URL.RawPath,
				RawQuery:    r.Request.URL.RawQuery,
				Fragment:    r.Request.URL.Fragment,
				RawFragment: r.Request.URL.RawFragment,
			},
			RawURL:           r.Request.URL.String(),
			Proto:            r.Request.Proto,
			ProtoMajor:       r.Request.ProtoMajor,
			ProtoMinor:       r.Request.ProtoMinor,
			Header:           r.Request.Header,
			ContentLength:    r.Request.ContentLength,
			TransferEncoding: r.Request.TransferEncoding,
			Host:             r.Request.Host,
			Trailer:          r.Request.Trailer,
			RemoteAddr:       r.Request.RemoteAddr,
			RequestURI:       r.Request.RequestURI,
		},
		Response: ResponseVar{
			Proto:            r.Proto,
			ProtoMajor:       r.ProtoMajor,
			ProtoMinor:       r.ProtoMinor,
			Header:           r.Header,
			ContentLength:    r.ContentLength,
			TransferEncoding: r.TransferEncoding,
			Trailer:          r.Trailer,
			Status:           r.Status,
			StatusCode:       r.StatusCode,
		},
	}

	ctx = ruleHTTP.WithResponse(ctx, r)

	if _, err := engine.Apply(ctx, vars); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (l *Layer) getResponseRuleEngine(ctx context.Context, layerRevision int, options *LayerOptions) (*rule.Engine[*ResponseVars], error) {
	engine, err := l.responseRuleEngine.Get(ctx, layerRevision, options)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return engine, nil
}