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| 1 | +// Copyright Envoy AI Gateway Authors |
| 2 | +// SPDX-License-Identifier: Apache-2.0 |
| 3 | +// The full text of the Apache license is available in the LICENSE file at |
| 4 | +// the root of the repo. |
| 5 | + |
| 6 | +package translator |
| 7 | + |
| 8 | +import ( |
| 9 | + "cmp" |
| 10 | + "fmt" |
| 11 | + "io" |
| 12 | + "log/slog" |
| 13 | + "strconv" |
| 14 | + "strings" |
| 15 | + |
| 16 | + "github.com/tidwall/sjson" |
| 17 | + |
| 18 | + "github.com/envoyproxy/ai-gateway/internal/apischema/anthropic" |
| 19 | + "github.com/envoyproxy/ai-gateway/internal/apischema/openai" |
| 20 | + "github.com/envoyproxy/ai-gateway/internal/internalapi" |
| 21 | + "github.com/envoyproxy/ai-gateway/internal/json" |
| 22 | + "github.com/envoyproxy/ai-gateway/internal/metrics" |
| 23 | + "github.com/envoyproxy/ai-gateway/internal/tracing/tracingapi" |
| 24 | +) |
| 25 | + |
| 26 | +// NewAnthropicToChatCompletionOpenAITranslator implements [Factory] for Anthropic to OpenAI ChatCompletion translation. |
| 27 | +// This translator converts Anthropic API format to OpenAI ChatCompletion API requests. |
| 28 | +func NewAnthropicToChatCompletionOpenAITranslator(version string, modelNameOverride internalapi.ModelNameOverride) AnthropicMessagesTranslator { |
| 29 | + // TODO: use "version" in APISchema struct to set the specific prefix if needed like OpenAI does. However, two questions: |
| 30 | + // * Is there any "Anthropic compatible" API that uses a different prefix like OpenAI does? |
| 31 | + // * Even if there is, we should refactor the APISchema struct to have "prefix" field instead of abusing "version" field. |
| 32 | + _ = version |
| 33 | + passthroughTranslator := NewAnthropicToAnthropicTranslator(version, modelNameOverride) |
| 34 | + return &anthropicToOpenAIV1ChatCompletionTranslator{passthroughTranslator: &passthroughTranslator, modelNameOverride: modelNameOverride} |
| 35 | +} |
| 36 | + |
| 37 | +type anthropicToOpenAIV1ChatCompletionTranslator struct { |
| 38 | + passthroughTranslator *AnthropicMessagesTranslator |
| 39 | + modelNameOverride internalapi.ModelNameOverride |
| 40 | + requestModel internalapi.RequestModel |
| 41 | + stream bool |
| 42 | + streamState *openAIStreamToAnthropicState |
| 43 | + // Redaction configuration for debug logging |
| 44 | + debugLogEnabled bool |
| 45 | + enableRedaction bool |
| 46 | + logger *slog.Logger |
| 47 | +} |
| 48 | + |
| 49 | +// RequestBody implements [AnthropicMessagesTranslator.RequestBody]. |
| 50 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) RequestBody(_ []byte, body *anthropic.MessagesRequest, _ bool) ( |
| 51 | + newHeaders []internalapi.Header, newBody []byte, err error, |
| 52 | +) { |
| 53 | + // Set translator config based on Anthropic message request |
| 54 | + a.stream = body.Stream |
| 55 | + // Store the request model to use as fallback for response model |
| 56 | + a.requestModel = cmp.Or(a.modelNameOverride, body.Model) |
| 57 | + |
| 58 | + // Convert Anthropic message request body to OpenAI format. |
| 59 | + openAIReq := buildOpenAIChatCompletionRequest(body, a.modelNameOverride) |
| 60 | + |
| 61 | + newBody, err = json.Marshal(openAIReq) |
| 62 | + if err != nil { |
| 63 | + return nil, nil, fmt.Errorf("failed to marshal OpenAI request: %w", err) |
| 64 | + } |
| 65 | + |
| 66 | + // Add stop sequences via sjson because ChatCompletionNewParamsStopUnion (from the external openai-go SDK) |
| 67 | + // requires importing the external package. Using sjson avoids that dependency. |
| 68 | + if len(body.StopSequences) > 0 { |
| 69 | + newBody, err = sjson.SetBytesOptions(newBody, "stop", body.StopSequences, sjsonOptions) |
| 70 | + if err != nil { |
| 71 | + return nil, nil, fmt.Errorf("failed to set stop sequences: %w", err) |
| 72 | + } |
| 73 | + } |
| 74 | + |
| 75 | + if body.Stream { |
| 76 | + a.streamState = &openAIStreamToAnthropicState{ |
| 77 | + activeTools: make(map[int64]*streamToolCall), |
| 78 | + requestModel: a.requestModel, |
| 79 | + } |
| 80 | + } |
| 81 | + |
| 82 | + newHeaders = []internalapi.Header{ |
| 83 | + {pathHeaderName, "/v1/chat/completions"}, |
| 84 | + {contentLengthHeaderName, strconv.Itoa(len(newBody))}, |
| 85 | + } |
| 86 | + return |
| 87 | +} |
| 88 | + |
| 89 | +// ResponseHeaders implements [AnthropicMessagesTranslator.ResponseHeaders]. |
| 90 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) ResponseHeaders(_ map[string]string) ( |
| 91 | + newHeaders []internalapi.Header, err error, |
| 92 | +) { |
| 93 | + return nil, nil |
| 94 | +} |
| 95 | + |
| 96 | +// ResponseBody implements [AnthropicMessagesTranslator.ResponseBody]. |
| 97 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) ResponseBody(_ map[string]string, body io.Reader, endOfStream bool, span tracingapi.MessageSpan) ( |
| 98 | + newHeaders []internalapi.Header, newBody []byte, tokenUsage metrics.TokenUsage, responseModel string, err error, |
| 99 | +) { |
| 100 | + if a.stream { |
| 101 | + return a.responseBodyStreaming(body, endOfStream) |
| 102 | + } |
| 103 | + return a.responseBodyNonStreaming(body, span) |
| 104 | +} |
| 105 | + |
| 106 | +// responseBodyNonStreaming converts an OpenAI ChatCompletionResponse to Anthropic MessagesResponse format. |
| 107 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) responseBodyNonStreaming(body io.Reader, span tracingapi.MessageSpan) ( |
| 108 | + newHeaders []internalapi.Header, newBody []byte, tokenUsage metrics.TokenUsage, responseModel string, err error, |
| 109 | +) { |
| 110 | + responseModel = a.requestModel |
| 111 | + |
| 112 | + openAIResp := &openai.ChatCompletionResponse{} |
| 113 | + if err = json.NewDecoder(body).Decode(openAIResp); err != nil { |
| 114 | + return nil, nil, tokenUsage, responseModel, fmt.Errorf("failed to unmarshal OpenAI response: %w", err) |
| 115 | + } |
| 116 | + |
| 117 | + responseModel = cmp.Or(openAIResp.Model, a.requestModel) |
| 118 | + |
| 119 | + tokenUsage = metrics.ExtractTokenUsageFromExplicitCaching( |
| 120 | + int64(openAIResp.Usage.PromptTokens), |
| 121 | + int64(openAIResp.Usage.CompletionTokens), |
| 122 | + nil, |
| 123 | + nil, |
| 124 | + ) |
| 125 | + |
| 126 | + anthropicResp := openAIResponseToAnthropic(openAIResp, responseModel) |
| 127 | + |
| 128 | + // Redact and log response when enabled |
| 129 | + if a.debugLogEnabled && a.enableRedaction && a.logger != nil { |
| 130 | + redactedResp := a.RedactAnthropicBody(anthropicResp) |
| 131 | + if jsonBody, marshalErr := json.Marshal(redactedResp); marshalErr == nil { |
| 132 | + a.logger.Debug("response body processing", slog.Any("response", string(jsonBody))) |
| 133 | + } |
| 134 | + } |
| 135 | + |
| 136 | + if span != nil { |
| 137 | + span.RecordResponse(anthropicResp) |
| 138 | + } |
| 139 | + |
| 140 | + newBody, err = json.Marshal(anthropicResp) |
| 141 | + if err != nil { |
| 142 | + return nil, nil, tokenUsage, responseModel, fmt.Errorf("failed to marshal Anthropic response: %w", err) |
| 143 | + } |
| 144 | + newHeaders = []internalapi.Header{{contentLengthHeaderName, strconv.Itoa(len(newBody))}} |
| 145 | + return |
| 146 | +} |
| 147 | + |
| 148 | +// responseBodyStreaming handles converting OpenAI SSE chunks to Anthropic SSE events. |
| 149 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) responseBodyStreaming(body io.Reader, endOfStream bool) ( |
| 150 | + newHeaders []internalapi.Header, newBody []byte, tokenUsage metrics.TokenUsage, responseModel string, err error, |
| 151 | +) { |
| 152 | + responseModel = a.requestModel |
| 153 | + |
| 154 | + if a.streamState == nil { |
| 155 | + return nil, nil, tokenUsage, responseModel, fmt.Errorf("stream state not initialized") |
| 156 | + } |
| 157 | + |
| 158 | + // Read body into streamState's buffer |
| 159 | + if _, err = a.streamState.buffer.ReadFrom(body); err != nil { |
| 160 | + return nil, nil, tokenUsage, responseModel, fmt.Errorf("failed to read stream body: %w", err) |
| 161 | + } |
| 162 | + |
| 163 | + // Initialize out as a non-nil empty slice so that if no Anthropic events are emitted |
| 164 | + // (e.g., for finish_reason-only chunks or [DONE]), we still return a non-nil newBody. |
| 165 | + // A non-nil empty body tells Envoy to replace the chunk with nothing, suppressing the |
| 166 | + // raw upstream bytes instead of passing them through unchanged. |
| 167 | + out := make([]byte, 0) |
| 168 | + if err = a.streamState.processBuffer(&out, endOfStream); err != nil { |
| 169 | + return nil, nil, tokenUsage, responseModel, err |
| 170 | + } |
| 171 | + |
| 172 | + // Update responseModel if updated in streamState or take requested model |
| 173 | + responseModel = cmp.Or(a.streamState.model, a.requestModel) |
| 174 | + tokenUsage = a.streamState.tokenUsage |
| 175 | + |
| 176 | + // Always return newBody (even if empty) to suppress the original upstream chunk. |
| 177 | + newBody = out |
| 178 | + return |
| 179 | +} |
| 180 | + |
| 181 | +// ResponseError implements [AnthropicMessagesTranslator] for Anthropic to OpenAI translation. |
| 182 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) ResponseError(respHeaders map[string]string, r io.Reader) ( |
| 183 | + newHeaders []internalapi.Header, |
| 184 | + mutatedBody []byte, |
| 185 | + err error, |
| 186 | +) { |
| 187 | + statusCode := respHeaders[statusHeaderName] |
| 188 | + var anthropicError anthropic.ErrorResponse |
| 189 | + |
| 190 | + if strings.Contains(respHeaders[contentTypeHeaderName], jsonContentType) { |
| 191 | + // OpenAI backend returned a structured JSON error; translate to Anthropic error format. |
| 192 | + var openaiErr openai.Error |
| 193 | + if err = json.NewDecoder(r).Decode(&openaiErr); err != nil { |
| 194 | + return nil, nil, fmt.Errorf("failed to unmarshal OpenAI error body: %w", err) |
| 195 | + } |
| 196 | + anthropicError = anthropic.ErrorResponse{ |
| 197 | + Type: "error", |
| 198 | + Error: anthropic.ErrorResponseMessage{ |
| 199 | + Type: openaiErr.Error.Type, |
| 200 | + Message: openaiErr.Error.Message, |
| 201 | + }, |
| 202 | + } |
| 203 | + } else { |
| 204 | + var buf []byte |
| 205 | + buf, err = io.ReadAll(r) |
| 206 | + if err != nil { |
| 207 | + return nil, nil, fmt.Errorf("failed to read error body: %w", err) |
| 208 | + } |
| 209 | + var typ string |
| 210 | + switch statusCode { |
| 211 | + case "400": |
| 212 | + typ = "invalid_request_error" |
| 213 | + case "401": |
| 214 | + typ = "authentication_error" |
| 215 | + case "403": |
| 216 | + typ = "permission_error" |
| 217 | + case "404": |
| 218 | + typ = "not_found_error" |
| 219 | + case "413": |
| 220 | + typ = "request_too_large" |
| 221 | + case "429": |
| 222 | + typ = "rate_limit_error" |
| 223 | + case "500": |
| 224 | + typ = "internal_server_error" |
| 225 | + case "503": |
| 226 | + typ = "service_unavailable_error" |
| 227 | + case "529": |
| 228 | + typ = "overloaded_error" |
| 229 | + default: |
| 230 | + typ = "internal_server_error" |
| 231 | + } |
| 232 | + anthropicError = anthropic.ErrorResponse{ |
| 233 | + Type: "error", // Always "error" at the top level. |
| 234 | + Error: anthropic.ErrorResponseMessage{Type: typ, Message: string(buf)}, |
| 235 | + } |
| 236 | + } |
| 237 | + |
| 238 | + mutatedBody, err = json.Marshal(anthropicError) |
| 239 | + if err != nil { |
| 240 | + return nil, nil, fmt.Errorf("failed to marshal error body: %w", err) |
| 241 | + } |
| 242 | + newHeaders = append(newHeaders, |
| 243 | + internalapi.Header{contentTypeHeaderName, jsonContentType}, |
| 244 | + internalapi.Header{contentLengthHeaderName, strconv.Itoa(len(mutatedBody))}, |
| 245 | + ) |
| 246 | + return |
| 247 | +} |
| 248 | + |
| 249 | +// SetRedactionConfig implements [AnthropicResponseRedactor.SetRedactionConfig]. |
| 250 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) SetRedactionConfig(debugLogEnabled, enableRedaction bool, logger *slog.Logger) { |
| 251 | + a.debugLogEnabled = debugLogEnabled |
| 252 | + a.enableRedaction = enableRedaction |
| 253 | + a.logger = logger |
| 254 | +} |
| 255 | + |
| 256 | +// RedactAnthropicBody implements [AnthropicResponseRedactor.RedactAnthropicBody]. |
| 257 | +// Creates a redacted copy of the Anthropic response for safe logging without modifying the original. |
| 258 | +func (a *anthropicToOpenAIV1ChatCompletionTranslator) RedactAnthropicBody(resp *anthropic.MessagesResponse) *anthropic.MessagesResponse { |
| 259 | + if resp == nil { |
| 260 | + return nil |
| 261 | + } |
| 262 | + |
| 263 | + // Create a shallow copy of the response |
| 264 | + redacted := *resp |
| 265 | + |
| 266 | + // Redact content blocks (contains AI-generated content) |
| 267 | + if len(resp.Content) > 0 { |
| 268 | + redacted.Content = make([]anthropic.MessagesContentBlock, len(resp.Content)) |
| 269 | + for i := range resp.Content { |
| 270 | + redacted.Content[i] = redactAnthropicContent(&resp.Content[i]) |
| 271 | + } |
| 272 | + } |
| 273 | + |
| 274 | + return &redacted |
| 275 | +} |
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