refactor: 实现 ConversionEngine 协议转换引擎，替代旧 protocol 包
引入 Canonical Model 和 ProtocolAdapter 架构，支持 OpenAI/Anthropic 协议间 无缝转换，统一 ProxyHandler 替代分散的 OpenAI/Anthropic Handler，简化 ProviderClient 为协议无关的 HTTP 发送器，Provider 新增 protocol 字段。
This commit is contained in:
371
backend/internal/handler/proxy_handler.go
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371
backend/internal/handler/proxy_handler.go
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package handler
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import (
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"bufio"
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"io"
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"net/http"
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"strings"
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"github.com/gin-gonic/gin"
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"go.uber.org/zap"
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"nex/backend/internal/conversion"
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"nex/backend/internal/domain"
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"nex/backend/internal/provider"
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"nex/backend/internal/service"
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)
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// ProxyHandler 统一代理处理器
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type ProxyHandler struct {
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engine *conversion.ConversionEngine
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client provider.ProviderClient
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routingService service.RoutingService
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providerService service.ProviderService
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statsService service.StatsService
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logger *zap.Logger
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}
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// NewProxyHandler 创建统一代理处理器
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func NewProxyHandler(engine *conversion.ConversionEngine, client provider.ProviderClient, routingService service.RoutingService, providerService service.ProviderService, statsService service.StatsService) *ProxyHandler {
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return &ProxyHandler{
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engine: engine,
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client: client,
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routingService: routingService,
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providerService: providerService,
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statsService: statsService,
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logger: zap.L(),
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}
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}
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// HandleProxy 处理代理请求
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func (h *ProxyHandler) HandleProxy(c *gin.Context) {
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// 从 URL 提取 clientProtocol: /{protocol}/v1/...
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clientProtocol := c.Param("protocol")
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if clientProtocol == "" {
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c.JSON(http.StatusBadRequest, gin.H{"error": "缺少协议前缀"})
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return
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}
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// 原始路径: /v1/{path}
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path := c.Param("path")
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if strings.HasPrefix(path, "/") {
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path = path[1:]
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}
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nativePath := "/v1/" + path
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// 读取请求体
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body, err := io.ReadAll(c.Request.Body)
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if err != nil {
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c.JSON(http.StatusBadRequest, gin.H{"error": "读取请求体失败"})
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return
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}
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// 解析 model 名称（从 JSON body 中提取，GET 请求无 body）
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modelName := ""
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if len(body) > 0 {
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modelName = extractModelName(body)
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}
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// 构建输入 HTTPRequestSpec
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inSpec := conversion.HTTPRequestSpec{
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URL: nativePath,
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Method: c.Request.Method,
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Headers: extractHeaders(c),
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Body: body,
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}
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// 路由
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routeResult, err := h.routingService.Route(modelName)
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if err != nil {
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// GET 请求或无法提取 model 时，直接转发到上游
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if len(body) == 0 || modelName == "" {
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h.forwardPassthrough(c, inSpec, clientProtocol)
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return
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}
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h.writeError(c, err, clientProtocol)
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return
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}
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// 确定 providerProtocol
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providerProtocol := routeResult.Provider.Protocol
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if providerProtocol == "" {
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providerProtocol = "openai"
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}
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// 构建 TargetProvider
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targetProvider := conversion.NewTargetProvider(
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routeResult.Provider.BaseURL,
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routeResult.Provider.APIKey,
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routeResult.Model.ModelName,
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)
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// 判断是否流式
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isStream := h.isStreamRequest(body, clientProtocol, nativePath)
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if isStream {
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h.handleStream(c, inSpec, clientProtocol, providerProtocol, targetProvider, routeResult)
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} else {
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h.handleNonStream(c, inSpec, clientProtocol, providerProtocol, targetProvider, routeResult)
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}
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}
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// handleNonStream 处理非流式请求
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func (h *ProxyHandler) handleNonStream(c *gin.Context, inSpec conversion.HTTPRequestSpec, clientProtocol, providerProtocol string, targetProvider *conversion.TargetProvider, routeResult *domain.RouteResult) {
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// 转换请求
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outSpec, err := h.engine.ConvertHttpRequest(inSpec, clientProtocol, providerProtocol, targetProvider)
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if err != nil {
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h.logger.Error("转换请求失败", zap.String("error", err.Error()))
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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// 发送请求
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resp, err := h.client.Send(c.Request.Context(), *outSpec)
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if err != nil {
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h.logger.Error("发送请求失败", zap.String("error", err.Error()))
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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// 转换响应
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interfaceType, _ := h.engine.DetectInterfaceType(inSpec.URL, clientProtocol)
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convertedResp, err := h.engine.ConvertHttpResponse(*resp, clientProtocol, providerProtocol, interfaceType)
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if err != nil {
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h.logger.Error("转换响应失败", zap.String("error", err.Error()))
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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// 设置响应头
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for k, v := range convertedResp.Headers {
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c.Header(k, v)
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}
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if c.GetHeader("Content-Type") == "" {
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c.Header("Content-Type", "application/json")
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}
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c.Data(convertedResp.StatusCode, "application/json", convertedResp.Body)
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go func() {
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_ = h.statsService.Record(routeResult.Provider.ID, routeResult.Model.ModelName)
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}()
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}
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// handleStream 处理流式请求
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func (h *ProxyHandler) handleStream(c *gin.Context, inSpec conversion.HTTPRequestSpec, clientProtocol, providerProtocol string, targetProvider *conversion.TargetProvider, routeResult *domain.RouteResult) {
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// 转换请求
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outSpec, err := h.engine.ConvertHttpRequest(inSpec, clientProtocol, providerProtocol, targetProvider)
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if err != nil {
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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// 创建流式转换器
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streamConverter, err := h.engine.CreateStreamConverter(clientProtocol, providerProtocol)
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if err != nil {
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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// 发送流式请求
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eventChan, err := h.client.SendStream(c.Request.Context(), *outSpec)
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if err != nil {
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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c.Header("Content-Type", "text/event-stream")
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c.Header("Cache-Control", "no-cache")
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c.Header("Connection", "keep-alive")
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writer := bufio.NewWriter(c.Writer)
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for event := range eventChan {
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if event.Error != nil {
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h.logger.Error("流读取错误", zap.String("error", event.Error.Error()))
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break
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}
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if event.Done {
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// flush 转换器
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chunks := streamConverter.Flush()
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for _, chunk := range chunks {
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writer.Write(chunk)
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writer.Flush()
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}
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break
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}
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chunks := streamConverter.ProcessChunk(event.Data)
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for _, chunk := range chunks {
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writer.Write(chunk)
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writer.Flush()
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}
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}
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go func() {
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_ = h.statsService.Record(routeResult.Provider.ID, routeResult.Model.ModelName)
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}()
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}
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// isStreamRequest 判断是否流式请求
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func (h *ProxyHandler) isStreamRequest(body []byte, clientProtocol, nativePath string) bool {
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ifaceType, _ := h.engine.DetectInterfaceType(nativePath, clientProtocol)
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if ifaceType != conversion.InterfaceTypeChat {
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return false
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}
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for i, b := range body {
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if b == '"' && i+8 <= len(body) {
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if string(body[i:i+8]) == `"stream"` {
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for j := i + 8; j < len(body) && j < i+20; j++ {
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if body[j] == 't' && j+3 < len(body) && string(body[j:j+4]) == "true" {
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return true
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}
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}
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}
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}
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}
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return false
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}
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// writeConversionError 写入转换错误
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func (h *ProxyHandler) writeConversionError(c *gin.Context, err error, clientProtocol string) {
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if convErr, ok := err.(*conversion.ConversionError); ok {
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body, statusCode, _ := h.engine.EncodeError(convErr, clientProtocol)
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c.Data(statusCode, "application/json", body)
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return
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}
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c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
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}
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// writeError 写入路由错误
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func (h *ProxyHandler) writeError(c *gin.Context, err error, clientProtocol string) {
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c.JSON(http.StatusNotFound, gin.H{"error": err.Error()})
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}
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// forwardPassthrough 直接转发请求到上游（用于 GET 等无 model 的请求）
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func (h *ProxyHandler) forwardPassthrough(c *gin.Context, inSpec conversion.HTTPRequestSpec, clientProtocol string) {
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registry := h.engine.GetRegistry()
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adapter, err := registry.Get(clientProtocol)
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if err != nil {
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c.JSON(http.StatusBadRequest, gin.H{"error": "不支持的协议: " + clientProtocol})
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return
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}
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providers, err := h.providerService.List()
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if err != nil || len(providers) == 0 {
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h.logger.Warn("无可用供应商转发 GET 请求", zap.String("path", inSpec.URL))
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c.JSON(http.StatusNotFound, gin.H{"error": "没有可用的供应商。请先创建供应商和模型。"})
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return
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}
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p := providers[0]
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providerProtocol := p.Protocol
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if providerProtocol == "" {
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providerProtocol = "openai"
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}
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ifaceType := adapter.DetectInterfaceType(inSpec.URL)
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targetProvider := conversion.NewTargetProvider(p.BaseURL, p.APIKey, "")
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var outSpec *conversion.HTTPRequestSpec
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if clientProtocol == providerProtocol {
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upstreamURL := p.BaseURL + inSpec.URL
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headers := adapter.BuildHeaders(targetProvider)
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if _, ok := headers["Content-Type"]; !ok {
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headers["Content-Type"] = "application/json"
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}
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outSpec = &conversion.HTTPRequestSpec{
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URL: upstreamURL,
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Method: inSpec.Method,
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Headers: headers,
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Body: inSpec.Body,
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}
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} else {
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outSpec, err = h.engine.ConvertHttpRequest(inSpec, clientProtocol, providerProtocol, targetProvider)
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if err != nil {
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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}
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resp, err := h.client.Send(c.Request.Context(), *outSpec)
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if err != nil {
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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convertedResp, err := h.engine.ConvertHttpResponse(*resp, clientProtocol, providerProtocol, ifaceType)
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if err != nil {
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h.writeConversionError(c, err, clientProtocol)
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return
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}
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for k, v := range convertedResp.Headers {
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c.Header(k, v)
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}
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if c.GetHeader("Content-Type") == "" {
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c.Header("Content-Type", "application/json")
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}
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c.Data(convertedResp.StatusCode, "application/json", convertedResp.Body)
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}
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// extractModelName 从 JSON body 中提取 model
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func extractModelName(body []byte) string {
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inQuote := false
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escaped := false
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keyStart := -1
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keyEnd := -1
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lookingForKey := true
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lookingForValue := false
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valueStart := -1
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for i := 0; i < len(body); i++ {
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b := body[i]
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if escaped {
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escaped = false
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continue
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}
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if b == '\\' {
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escaped = true
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continue
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}
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if b == '"' {
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if !inQuote {
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inQuote = true
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if lookingForKey {
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keyStart = i + 1
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}
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if lookingForValue {
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valueStart = i + 1
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}
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} else {
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inQuote = false
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if lookingForKey && keyStart >= 0 {
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keyEnd = i
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if string(body[keyStart:keyEnd]) == "model" {
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lookingForKey = false
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lookingForValue = true
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}
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} else if lookingForValue && valueStart >= 0 {
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return string(body[valueStart:i])
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}
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}
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}
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if !inQuote && lookingForValue && b == ':' {
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// 等待值开始
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}
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}
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return ""
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}
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// extractHeaders 从 Gin context 提取请求头
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func extractHeaders(c *gin.Context) map[string]string {
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headers := make(map[string]string)
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for k, vs := range c.Request.Header {
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if len(vs) > 0 {
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headers[k] = vs[0]
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}
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}
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return headers
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}
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