feat: add nginx rewrite compatible wasm plugin (#3823)

Signed-off-by: johnlanni <zty98751@alibaba-inc.com>

plugins/wasm-go/extensions/nginx-rewrite-compatible/pkg/rewrite.go

@@ -0,0 +1,245 @@
+package pkg
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
+	"github.com/higress-group/wasm-go/pkg/log"
+	"github.com/higress-group/wasm-go/pkg/wrapper"
+)
+
+const (
+	propertyNamespace = "nginx_rewrite_compatible"
+	headerPrefix      = "x-higress-rewrite-var-"
+	argVarPrefix      = "arg_"
+	httpVarPrefix     = "http_"
+	cookieVarPrefix   = "cookie_"
+)
+
+func (c PluginConfig) Apply(ctx wrapper.HttpContext, logger log.Log) (bool, error) {
+	originalPath, err := proxywasm.GetHttpRequestHeader(":path")
+	if err != nil || originalPath == "" {
+		originalPath = ctx.Path()
+	}
+	if originalPath == "" {
+		return false, fmt.Errorf("request path is empty")
+	}
+
+	currentPath, currentQuery := splitPathAndQuery(originalPath)
+	vars := map[string]string{}
+	passHeaders := map[string]bool{}
+	requestHeaders := map[string]string{}
+	requestCookies := map[string]string{}
+	changed := false
+
+	for i, rule := range c.Rules {
+		matches := rule.compiled.FindStringSubmatchIndex(currentPath)
+		if matches == nil {
+			continue
+		}
+
+		if !changed {
+			ctx.DisableReroute()
+		}
+		changed = true
+
+		newPath := rule.compiled.ReplaceAllString(currentPath, rule.Replacement)
+		if newPath == "" {
+			return false, fmt.Errorf("rule %d produced an empty path", i)
+		}
+
+		switch {
+		case rule.QueryTemplate != "":
+			currentQuery = expandTemplate(rule, currentPath, matches, rule.QueryTemplate)
+		case rule.QueryAppend != "":
+			currentQuery = appendQuery(currentQuery, expandTemplate(rule, currentPath, matches, rule.QueryAppend))
+		}
+
+		for _, setVar := range rule.SetVars {
+			value := captureGroupValue(currentPath, matches, setVar.CaptureGroup)
+			vars[setVar.Name] = value
+			passHeaders[setVar.Name] = rule.PassToUpstream
+		}
+
+		logger.Debugf("rule %d matched path %q and rewrote it to %q", i, currentPath, newPath)
+		currentPath = newPath
+
+		if rule.Mode == ModeBreak {
+			break
+		}
+	}
+
+	if !changed {
+		return false, nil
+	}
+
+	for name, value := range vars {
+		switch {
+		case strings.HasPrefix(name, argVarPrefix):
+			currentQuery = setQueryParam(currentQuery, strings.TrimPrefix(name, argVarPrefix), value)
+		case strings.HasPrefix(name, httpVarPrefix):
+			requestHeaders[buildRequestHeaderName(strings.TrimPrefix(name, httpVarPrefix))] = value
+		case strings.HasPrefix(name, cookieVarPrefix):
+			requestCookies[strings.TrimPrefix(name, cookieVarPrefix)] = value
+		case value != "":
+			if err := proxywasm.SetProperty([]string{propertyNamespace, "vars", name}, []byte(value)); err != nil {
+				return false, fmt.Errorf("failed to set property for var %q: %w", name, err)
+			}
+		}
+
+		headerName := buildUpstreamHeaderName(name)
+		if passHeaders[name] {
+			if err := proxywasm.ReplaceHttpRequestHeader(headerName, value); err != nil {
+				return false, fmt.Errorf("failed to set upstream header for var %q: %w", name, err)
+			}
+			continue
+		}
+		if err := proxywasm.RemoveHttpRequestHeader(headerName); err != nil {
+			logger.Warnf("failed to remove upstream header %q: %v", headerName, err)
+		}
+	}
+
+	for name, value := range requestHeaders {
+		if err := proxywasm.ReplaceHttpRequestHeader(name, value); err != nil {
+			return false, fmt.Errorf("failed to set request header %q: %w", name, err)
+		}
+	}
+
+	if len(requestCookies) > 0 {
+		currentCookie, err := proxywasm.GetHttpRequestHeader("cookie")
+		if err != nil {
+			currentCookie = ""
+		}
+		updatedCookie := currentCookie
+		for name, value := range requestCookies {
+			updatedCookie = setCookie(updatedCookie, name, value)
+		}
+		if err := proxywasm.ReplaceHttpRequestHeader("cookie", updatedCookie); err != nil {
+			return false, fmt.Errorf("failed to set cookie header: %w", err)
+		}
+	}
+
+	finalPath := buildPath(currentPath, currentQuery)
+	if finalPath != originalPath {
+		if err := proxywasm.ReplaceHttpRequestHeader(":path", finalPath); err != nil {
+			return false, fmt.Errorf("failed to replace :path header: %w", err)
+		}
+	}
+
+	return true, nil
+}
+
+func splitPathAndQuery(path string) (string, string) {
+	pathOnly, query, found := strings.Cut(path, "?")
+	if !found {
+		return path, ""
+	}
+	return pathOnly, query
+}
+
+func buildPath(path string, query string) string {
+	if query == "" {
+		return path
+	}
+	return path + "?" + query
+}
+
+func appendQuery(existing string, suffix string) string {
+	if suffix == "" {
+		return existing
+	}
+	if existing == "" {
+		return suffix
+	}
+	return existing + "&" + suffix
+}
+
+func setQueryParam(existing string, key string, value string) string {
+	if key == "" {
+		return existing
+	}
+
+	parts := []string{}
+	replaced := false
+	if existing != "" {
+		for _, part := range strings.Split(existing, "&") {
+			if part == "" {
+				continue
+			}
+			name, _, _ := strings.Cut(part, "=")
+			if name != key {
+				parts = append(parts, part)
+				continue
+			}
+			if !replaced {
+				parts = append(parts, key+"="+value)
+				replaced = true
+			}
+		}
+	}
+	if !replaced {
+		parts = append(parts, key+"="+value)
+	}
+	return strings.Join(parts, "&")
+}
+
+func expandTemplate(rule Rule, currentPath string, matches []int, template string) string {
+	return string(rule.compiled.ExpandString(nil, template, currentPath, matches))
+}
+
+func captureGroupValue(currentPath string, matches []int, group int) string {
+	index := group * 2
+	if index+1 >= len(matches) {
+		return ""
+	}
+	start, end := matches[index], matches[index+1]
+	if start < 0 || end < 0 {
+		return ""
+	}
+	return currentPath[start:end]
+}
+
+func buildUpstreamHeaderName(name string) string {
+	sanitized := strings.ToLower(strings.TrimSpace(name))
+	sanitized = strings.ReplaceAll(sanitized, "_", "-")
+	sanitized = strings.ReplaceAll(sanitized, " ", "-")
+	return headerPrefix + sanitized
+}
+
+func buildRequestHeaderName(name string) string {
+	sanitized := strings.ToLower(strings.TrimSpace(name))
+	sanitized = strings.ReplaceAll(sanitized, "_", "-")
+	sanitized = strings.ReplaceAll(sanitized, " ", "-")
+	return sanitized
+}
+
+func setCookie(existing string, key string, value string) string {
+	if key == "" {
+		return existing
+	}
+
+	parts := []string{}
+	replaced := false
+	if existing != "" {
+		for _, part := range strings.Split(existing, ";") {
+			part = strings.TrimSpace(part)
+			if part == "" {
+				continue
+			}
+			name, _, _ := strings.Cut(part, "=")
+			if name != key {
+				parts = append(parts, part)
+				continue
+			}
+			if !replaced {
+				parts = append(parts, key+"="+value)
+				replaced = true
+			}
+		}
+	}
+	if !replaced {
+		parts = append(parts, key+"="+value)
+	}
+	return strings.Join(parts, "; ")
+}