Add wasm plugin contribution introduction (#47)

plugins/wasm-go/extensions/request-block/main.go

@@ -0,0 +1,153 @@
+// Copyright (c) 2022 Alibaba Group Holding Ltd.
+//
+// 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 main
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm"
+	"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm/types"
+	"github.com/tidwall/gjson"
+
+	"github.com/alibaba/higress/plugins/wasm-go/pkg/wrapper"
+)
+
+func main() {
+	wrapper.SetCtx(
+		"request-block",
+		wrapper.ParseConfigBy(parseConfig),
+		wrapper.ProcessRequestHeadersBy(onHttpRequestHeaders),
+		wrapper.ProcessRequestBodyBy(onHttpRequestBody),
+	)
+}
+
+type RequestBlockConfig struct {
+	blockedCode    uint32
+	blockedMessage string
+	caseSensitive  bool
+	blockUrls      []string
+	blockHeaders   []string
+	blockBodys     []string
+}
+
+func parseConfig(json gjson.Result, config *RequestBlockConfig, log wrapper.LogWrapper) error {
+	code := json.Get("blocked_code").Int()
+	if code != 0 && code > 100 && code < 600 {
+		config.blockedCode = uint32(code)
+	} else {
+		config.blockedCode = 403
+	}
+	config.blockedMessage = json.Get("blocked_message").String()
+	config.caseSensitive = json.Get("case_sensitive").Bool()
+	for _, item := range json.Get("block_urls").Array() {
+		url := item.String()
+		if url == "" {
+			continue
+		}
+		if config.caseSensitive {
+			config.blockUrls = append(config.blockUrls, url)
+		} else {
+			config.blockUrls = append(config.blockUrls, strings.ToLower(url))
+		}
+	}
+	for _, item := range json.Get("block_headers").Array() {
+		header := item.String()
+		if header == "" {
+			continue
+		}
+		if config.caseSensitive {
+			config.blockHeaders = append(config.blockHeaders, header)
+		} else {
+			config.blockHeaders = append(config.blockHeaders, strings.ToLower(header))
+		}
+	}
+	for _, item := range json.Get("block_bodys").Array() {
+		body := item.String()
+		if body == "" {
+			continue
+		}
+		if config.caseSensitive {
+			config.blockBodys = append(config.blockBodys, body)
+		} else {
+			config.blockBodys = append(config.blockBodys, strings.ToLower(body))
+		}
+	}
+	if len(config.blockUrls) == 0 && len(config.blockHeaders) == 0 &&
+		len(config.blockBodys) == 0 {
+		return errors.New("there is no block rules")
+	}
+	return nil
+}
+
+func onHttpRequestHeaders(ctx *wrapper.CommonHttpCtx[RequestBlockConfig], config RequestBlockConfig, needBody *bool, log wrapper.LogWrapper) types.Action {
+	if len(config.blockUrls) > 0 {
+		requestUrl, err := proxywasm.GetHttpRequestHeader(":path")
+		if err != nil {
+			log.Warnf("get path failed: %v", err)
+			return types.ActionContinue
+		}
+		if !config.caseSensitive {
+			requestUrl = strings.ToLower(requestUrl)
+		}
+		for _, blockUrl := range config.blockUrls {
+			if strings.Contains(requestUrl, blockUrl) {
+				proxywasm.SendHttpResponse(config.blockedCode, nil, []byte(config.blockedMessage), -1)
+				return types.ActionContinue
+			}
+		}
+	}
+	if len(config.blockHeaders) > 0 {
+		headers, err := proxywasm.GetHttpRequestHeaders()
+		if err != nil {
+			log.Warnf("get headers failed: %v", err)
+			return types.ActionContinue
+		}
+		var headerPairs []string
+		for _, kv := range headers {
+			headerPairs = append(headerPairs, fmt.Sprintf("%s\n%s", kv[0], kv[1]))
+		}
+		headerStr := strings.Join(headerPairs, "\n")
+		if !config.caseSensitive {
+			headerStr = strings.ToLower(headerStr)
+		}
+		for _, blockHeader := range config.blockHeaders {
+			if strings.Contains(headerStr, blockHeader) {
+				proxywasm.SendHttpResponse(config.blockedCode, nil, []byte(config.blockedMessage), -1)
+				return types.ActionContinue
+			}
+		}
+	}
+	if len(config.blockBodys) == 0 {
+		*needBody = false
+	}
+	return types.ActionContinue
+}
+
+func onHttpRequestBody(ctx *wrapper.CommonHttpCtx[RequestBlockConfig], config RequestBlockConfig, body []byte, log wrapper.LogWrapper) types.Action {
+	bodyStr := string(body)
+	if !config.caseSensitive {
+		bodyStr = strings.ToLower(bodyStr)
+	}
+	for _, blockBody := range config.blockBodys {
+		if strings.Contains(bodyStr, blockBody) {
+			proxywasm.SendHttpResponse(config.blockedCode, nil, []byte(config.blockedMessage), -1)
+			return types.ActionContinue
+		}
+	}
+	return types.ActionContinue
+
+}