1package provider
2
3// Amazon Bedrock Converse-Stream client.
4//
5// Endpoint: POST https://bedrock-runtime.{region}.amazonaws.com/model/{id}/converse-stream
6//
7// Auth: two paths supported.
8//
9// - **Bearer token** via AWS_BEARER_TOKEN_BEDROCK. Modern, simple,
10// `bedrock:CallWithBearerToken` IAM permission required.
11// - **SigV4 signing** via AWS_ACCESS_KEY_ID + AWS_SECRET_ACCESS_KEY
12// (+ optional AWS_SESSION_TOKEN for temporary credentials, e.g. SSO
13// or IRSA-issued). Hand-rolled here so we don't pull in aws-sdk-go-v2.
14//
15// If both are present, bearer wins (simpler / fewer moving parts).
16//
17// Wire format: AWS event-stream binary framing. Each message is:
18//
19// [4-byte total length BE]
20// [4-byte headers length BE]
21// [4-byte CRC32 of the 8-byte prelude]
22// [headers ...] each = [1B name-length][name][1B value-type][2B value-length][value]
23// [payload ...] payload-length = total - headers - 4 (trailer) - 12 (prelude+prelude-crc)
24// [4-byte CRC32 of message bytes minus trailer]
25//
26// We only consume the stream — never produce it — so we don't validate
27// CRCs (the TLS+TCP transport already protects in-flight bytes). We do
28// validate length-bounds to avoid OOB reads on a hostile / corrupted
29// stream.
30//
31// Event types we care about (from `:event-type` header):
32// - messageStart { role: "assistant" }
33// - contentBlockStart { contentBlockIndex, start: { toolUse: { toolUseId, name } } }
34// - contentBlockDelta { contentBlockIndex, delta: { text?, toolUse?: { input } } }
35// - contentBlockStop { contentBlockIndex }
36// - messageStop { stopReason }
37// - metadata { usage: { inputTokens, outputTokens } }
38
39import (
40 "bytes"
41 "context"
42 "crypto/hmac"
43 "crypto/sha256"
44 "encoding/binary"
45 "encoding/hex"
46 "encoding/json"
47 "fmt"
48 "io"
49 "net/http"
50 "net/url"
51 "os"
52 "sort"
53 "strings"
54 "time"
55)
56
57type bedrockClient struct {
58 // Auth mode is determined at construction time. Exactly one of
59 // bearerToken or sigv4 is populated.
60 bearerToken string
61 sigv4 *bedrockSigV4Creds
62
63 region string
64 baseURL string
65 http *http.Client
66}
67
68// bedrockSigV4Creds holds the IAM credentials used to sign each request.
69type bedrockSigV4Creds struct {
70 accessKeyID string
71 secretAccessKey string
72 sessionToken string // optional; STS / SSO / IRSA temp creds
73}
74
75// NewBedrockClient returns a Bedrock client.
76//
77// Auth resolution (first match wins):
78//
79// 1. apiKey == real bearer-ish string (not "<aws>") -> bearer route.
80// 2. AWS_BEARER_TOKEN_BEDROCK env var -> bearer route.
81// 3. AWS_ACCESS_KEY_ID + AWS_SECRET_ACCESS_KEY (+ optional
82// AWS_SESSION_TOKEN) -> SigV4 route.
83// 4. AWS_PROFILE -> read ~/.aws/credentials, take that profile's keys.
84//
85// region defaults to us-east-1 unless AWS_REGION / AWS_DEFAULT_REGION is
86// set or the baseURL embeds a region.
87func NewBedrockClient(apiKey, baseURL string) Client {
88 region := os.Getenv("AWS_REGION")
89 if region == "" {
90 region = os.Getenv("AWS_DEFAULT_REGION")
91 }
92 if region == "" {
93 region = "us-east-1"
94 }
95 if baseURL == "" {
96 baseURL = "https://bedrock-runtime." + region + ".amazonaws.com"
97 }
98 c := &bedrockClient{
99 region: region,
100 baseURL: strings.TrimRight(baseURL, "/"),
101 http: &http.Client{Timeout: 0},
102 }
103
104 // Bearer route.
105 token := apiKey
106 if token == "" || token == "<aws>" {
107 token = os.Getenv("AWS_BEARER_TOKEN_BEDROCK")
108 }
109 if token != "" && token != "<aws>" {
110 c.bearerToken = token
111 return c
112 }
113
114 // SigV4 route: env vars first.
115 ak := os.Getenv("AWS_ACCESS_KEY_ID")
116 sk := os.Getenv("AWS_SECRET_ACCESS_KEY")
117 st := os.Getenv("AWS_SESSION_TOKEN")
118 if ak != "" && sk != "" {
119 c.sigv4 = &bedrockSigV4Creds{accessKeyID: ak, secretAccessKey: sk, sessionToken: st}
120 return c
121 }
122
123 // SigV4 route: ~/.aws/credentials via AWS_PROFILE.
124 if profile := os.Getenv("AWS_PROFILE"); profile != "" {
125 if creds, err := readAWSCredentialsFile(profile); err == nil {
126 c.sigv4 = creds
127 return c
128 }
129 }
130
131 return &unimplementedClient{
132 name: "amazon-bedrock",
133 hint: "no Bedrock credentials found (set AWS_BEARER_TOKEN_BEDROCK, AWS_ACCESS_KEY_ID+AWS_SECRET_ACCESS_KEY, or AWS_PROFILE)",
134 }
135}
136
137// readAWSCredentialsFile parses ~/.aws/credentials and returns the
138// access-key/secret-key (and optional session-token) for the named
139// profile. The file is an INI-like format with `[profile]` headers.
140func readAWSCredentialsFile(profile string) (*bedrockSigV4Creds, error) {
141 home, err := os.UserHomeDir()
142 if err != nil {
143 return nil, err
144 }
145 b, err := os.ReadFile(home + "/.aws/credentials")
146 if err != nil {
147 return nil, err
148 }
149 var current string
150 creds := map[string]map[string]string{}
151 for _, line := range strings.Split(string(b), "\n") {
152 line = strings.TrimSpace(line)
153 if line == "" || strings.HasPrefix(line, "#") {
154 continue
155 }
156 if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
157 current = strings.TrimSpace(line[1 : len(line)-1])
158 creds[current] = map[string]string{}
159 continue
160 }
161 if current == "" {
162 continue
163 }
164 eq := strings.IndexByte(line, '=')
165 if eq < 0 {
166 continue
167 }
168 k := strings.TrimSpace(line[:eq])
169 v := strings.TrimSpace(line[eq+1:])
170 creds[current][k] = v
171 }
172 p, ok := creds[profile]
173 if !ok {
174 return nil, fmt.Errorf("aws profile %q not found in ~/.aws/credentials", profile)
175 }
176 ak := p["aws_access_key_id"]
177 sk := p["aws_secret_access_key"]
178 if ak == "" || sk == "" {
179 return nil, fmt.Errorf("aws profile %q missing aws_access_key_id or aws_secret_access_key", profile)
180 }
181 return &bedrockSigV4Creds{
182 accessKeyID: ak,
183 secretAccessKey: sk,
184 sessionToken: p["aws_session_token"],
185 }, nil
186}
187
188func (c *bedrockClient) Name() string { return "amazon-bedrock" }
189
190// ---- request building ----
191
192type bedrockMessage struct {
193 Role string `json:"role"`
194 Content []map[string]interface{} `json:"content"`
195}
196
197type bedrockToolSpec struct {
198 ToolSpec struct {
199 Name string `json:"name"`
200 Description string `json:"description,omitempty"`
201 InputSchema struct {
202 JSON json.RawMessage `json:"json"`
203 } `json:"inputSchema"`
204 } `json:"toolSpec"`
205}
206
207type bedrockRequest struct {
208 Messages []bedrockMessage `json:"messages"`
209 System []map[string]string `json:"system,omitempty"`
210 InferenceConfig struct {
211 MaxTokens int `json:"maxTokens,omitempty"`
212 Temperature *float32 `json:"temperature,omitempty"`
213 } `json:"inferenceConfig,omitempty"`
214 ToolConfig *struct {
215 Tools []bedrockToolSpec `json:"tools"`
216 } `json:"toolConfig,omitempty"`
217}
218
219func normalizeBedrockToolResults(msgs []Message) []Message {
220 resultByID := map[string]ToolResultBlock{}
221 for _, m := range msgs {
222 for _, c := range m.Content {
223 if tr, ok := c.(ToolResultBlock); ok {
224 if _, exists := resultByID[tr.CallID]; !exists {
225 resultByID[tr.CallID] = tr
226 }
227 }
228 }
229 }
230
231 out := make([]Message, 0, len(msgs))
232 for _, m := range msgs {
233 copy := m
234 copy.Content = nil
235 var toolCalls []ToolCallBlock
236 for _, c := range m.Content {
237 switch v := c.(type) {
238 case ToolResultBlock:
239 // Bedrock requires toolResult blocks immediately after the
240 // assistant toolUse they answer. Reinsert them from the
241 // assistant pass below instead of preserving their original
242 // location, which may be separated by user text in active
243 // sessions.
244 continue
245 case ToolCallBlock:
246 toolCalls = append(toolCalls, v)
247 }
248 copy.Content = append(copy.Content, c)
249 }
250 if len(copy.Content) > 0 {
251 out = append(out, copy)
252 }
253 if m.Role != RoleAssistant || len(toolCalls) == 0 {
254 continue
255 }
256
257 results := make([]Content, 0, len(toolCalls))
258 for _, tc := range toolCalls {
259 if tr, ok := resultByID[tc.ID]; ok {
260 results = append(results, tr)
261 continue
262 }
263 results = append(results, ToolResultBlock{
264 CallID: tc.ID,
265 IsError: true,
266 Content: []Content{TextBlock{Text: "tool call did not complete before the next user message"}},
267 })
268 }
269 out = append(out, Message{Role: RoleTool, Content: results, Time: m.Time})
270 }
271 return out
272}
273
274func (c *bedrockClient) buildRequest(req Request) (*bedrockRequest, error) {
275 out := &bedrockRequest{}
276 if req.System != "" {
277 out.System = []map[string]string{{"text": req.System}}
278 }
279 out.InferenceConfig.Temperature = req.Temperature
280 out.InferenceConfig.MaxTokens = req.MaxTokens
281 if out.InferenceConfig.MaxTokens == 0 {
282 out.InferenceConfig.MaxTokens = 4096
283 }
284 for _, m := range normalizeBedrockToolResults(req.Messages) {
285 role := string(m.Role)
286 if role == "tool" {
287 role = "user"
288 }
289 bm := bedrockMessage{Role: role}
290 for _, c := range m.Content {
291 switch v := c.(type) {
292 case TextBlock:
293 bm.Content = append(bm.Content, map[string]interface{}{"text": v.Text})
294 case ToolCallBlock:
295 var input map[string]interface{}
296 _ = json.Unmarshal(v.Arguments, &input)
297 if input == nil {
298 input = map[string]interface{}{}
299 }
300 bm.Content = append(bm.Content, map[string]interface{}{
301 "toolUse": map[string]interface{}{
302 "toolUseId": v.ID, "name": v.Name, "input": input,
303 },
304 })
305 case ToolResultBlock:
306 var resultContent []map[string]interface{}
307 for _, inner := range v.Content {
308 if tb, ok := inner.(TextBlock); ok {
309 resultContent = append(resultContent, map[string]interface{}{"text": tb.Text})
310 }
311 }
312 status := "success"
313 if v.IsError {
314 status = "error"
315 }
316 bm.Content = append(bm.Content, map[string]interface{}{
317 "toolResult": map[string]interface{}{
318 "toolUseId": v.CallID,
319 "content": resultContent,
320 "status": status,
321 },
322 })
323 }
324 }
325 if len(bm.Content) == 0 {
326 continue
327 }
328 out.Messages = append(out.Messages, bm)
329 }
330 if len(req.Tools) > 0 {
331 tc := struct {
332 Tools []bedrockToolSpec `json:"tools"`
333 }{}
334 for _, t := range req.Tools {
335 var ts bedrockToolSpec
336 ts.ToolSpec.Name = t.Name
337 ts.ToolSpec.Description = t.Description
338 ts.ToolSpec.InputSchema.JSON = t.Schema
339 tc.Tools = append(tc.Tools, ts)
340 }
341 out.ToolConfig = &tc
342 }
343 return out, nil
344}
345
346// resolveBedrockInferenceProfileID maps a bare foundation-model ID to
347// its region-matched cross-region inference-profile ID.
348//
349// Several newer Bedrock models (Anthropic Claude 4.x, DeepSeek, etc.)
350// cannot be invoked with on-demand throughput by their plain
351// foundation-model ID; Bedrock returns HTTP 400 demanding "the ID or
352// ARN of an inference profile that contains this model". The profile
353// ID is the same model ID with a geographic prefix (us/eu/apac/...).
354//
355// We only rewrite IDs that (a) lack an existing geo prefix and (b)
356// belong to a model family that requires a profile. IDs that already
357// carry a prefix (e.g. "eu.anthropic...", "global.anthropic...") or
358// fully-qualified ARNs are returned unchanged, so explicit user
359// choices and custom application inference profiles still work.
360func resolveBedrockInferenceProfileID(modelID, region string) string {
361 if modelID == "" {
362 return modelID
363 }
364 // ARNs are already inference-profile references; leave untouched.
365 if strings.HasPrefix(modelID, "arn:") {
366 return modelID
367 }
368 // Already geo-prefixed (us. / eu. / apac. / ap. / us-gov. / global.)?
369 if bedrockHasGeoPrefix(modelID) {
370 return modelID
371 }
372 if !bedrockRequiresInferenceProfile(modelID) {
373 return modelID
374 }
375 prefix := bedrockGeoPrefixForRegion(region)
376 if prefix == "" {
377 return modelID
378 }
379 return prefix + "." + modelID
380}
381
382// bedrockGeoPrefixes are the cross-region inference-profile geo
383// prefixes Bedrock uses. A model ID that starts with one of these
384// (followed by a dot) is already a profile reference.
385var bedrockGeoPrefixes = []string{"us-gov", "us", "eu", "apac", "ap", "global", "au"}
386
387func bedrockHasGeoPrefix(modelID string) bool {
388 for _, p := range bedrockGeoPrefixes {
389 if strings.HasPrefix(modelID, p+".") {
390 return true
391 }
392 }
393 return false
394}
395
396// bedrockRequiresInferenceProfile reports whether a bare
397// foundation-model ID is one of the families AWS only exposes through
398// a cross-region inference profile for on-demand throughput.
399func bedrockRequiresInferenceProfile(modelID string) bool {
400 switch {
401 case strings.HasPrefix(modelID, "anthropic.claude-"):
402 return true
403 case strings.HasPrefix(modelID, "deepseek."):
404 return true
405 default:
406 return false
407 }
408}
409
410// bedrockGeoPrefixForRegion maps an AWS region to the geo prefix used
411// by its cross-region inference profiles. Returns "" when the region
412// has no known mapping, in which case the model ID is left unchanged.
413func bedrockGeoPrefixForRegion(region string) string {
414 switch {
415 case region == "":
416 return "us"
417 case strings.HasPrefix(region, "us-gov-"):
418 return "us-gov"
419 case strings.HasPrefix(region, "us-"):
420 return "us"
421 case strings.HasPrefix(region, "eu-"):
422 return "eu"
423 case strings.HasPrefix(region, "ap-"):
424 return "apac"
425 case strings.HasPrefix(region, "ca-"):
426 return "us"
427 case strings.HasPrefix(region, "sa-"):
428 return "us"
429 default:
430 return "us"
431 }
432}
433
434func (c *bedrockClient) Stream(ctx context.Context, req Request) (<-chan Event, error) {
435 wire, err := c.buildRequest(req)
436 if err != nil {
437 return nil, err
438 }
439 body, err := json.Marshal(wire)
440 if err != nil {
441 return nil, err
442 }
443 modelID := resolveBedrockInferenceProfileID(req.Model, c.region)
444 url := c.baseURL + "/model/" + modelID + "/converse-stream"
445 httpReq, err := http.NewRequestWithContext(ctx, "POST", url, bytes.NewReader(body))
446 if err != nil {
447 return nil, err
448 }
449 httpReq.Header.Set("content-type", "application/json")
450 httpReq.Header.Set("accept", "application/vnd.amazon.eventstream")
451 if c.bearerToken != "" {
452 httpReq.Header.Set("authorization", "Bearer "+c.bearerToken)
453 } else if c.sigv4 != nil {
454 if err := signSigV4(httpReq, body, "bedrock", c.region, c.sigv4, time.Now().UTC()); err != nil {
455 return nil, fmt.Errorf("bedrock: sigv4 sign: %w", err)
456 }
457 } else {
458 return nil, fmt.Errorf("bedrock: no auth configured")
459 }
460 resp, err := c.http.Do(httpReq)
461 if err != nil {
462 return nil, fmt.Errorf("bedrock: %w", err)
463 }
464 if resp.StatusCode != http.StatusOK {
465 b, _ := io.ReadAll(resp.Body)
466 resp.Body.Close()
467 msg := strings.TrimSpace(string(b))
468 // A 403 on the bearer route is almost always a region mismatch:
469 // short-term Bedrock API keys are scoped to the region of the
470 // console session that minted them, but zot defaults to
471 // us-east-1. Surface the resolved region and the fix so the user
472 // is not left guessing why a freshly-copied key is "invalid".
473 if resp.StatusCode == http.StatusForbidden && c.bearerToken != "" {
474 return nil, fmt.Errorf(
475 "bedrock: http 403 (region=%s): %s\nhint: Bedrock API keys are region-scoped. If your key was created in another region, set AWS_REGION (e.g. AWS_REGION=eu-central-1) or pass --base-url https://bedrock-runtime.<region>.amazonaws.com",
476 c.region, msg)
477 }
478 return nil, fmt.Errorf("bedrock: http %d: %s", resp.StatusCode, msg)
479 }
480 out := make(chan Event, 16)
481 go c.runStream(ctx, resp, req, out)
482 return out, nil
483}
484
485func (c *bedrockClient) runStream(ctx context.Context, resp *http.Response, req Request, out chan<- Event) {
486 defer close(out)
487 defer resp.Body.Close()
488
489 out <- EventStart{Provider: "amazon-bedrock", Model: req.Model}
490
491 // State accumulated across deltas.
492 contentBlocks := map[int]*bedrockBlockState{}
493 stop := StopEnd
494 finalMsg := Message{Role: RoleAssistant, Time: time.Now()}
495 var usage Usage
496
497 for {
498 if ctx.Err() != nil {
499 stop = StopAborted
500 break
501 }
502 evt, err := readEventStreamMessage(resp.Body)
503 if err != nil {
504 if err == io.EOF {
505 break
506 }
507 out <- EventDone{Stop: StopError, Err: err, Message: finalMsg}
508 return
509 }
510 eventType := evt.headerString(":event-type")
511 if eventType == "" {
512 eventType = bedrockEventTypeFromPayload(evt.payload)
513 }
514 messageType := evt.headerString(":message-type")
515 if messageType == "exception" {
516 out <- EventDone{Stop: StopError, Err: fmt.Errorf("bedrock exception (%s): %s", evt.headerString(":exception-type"), string(evt.payload)), Message: finalMsg}
517 return
518 }
519 switch eventType {
520 case "messageStart":
521 // nothing to do; role is always "assistant"
522 case "contentBlockStart":
523 var d struct {
524 ContentBlockIndex int `json:"contentBlockIndex"`
525 Start struct {
526 ToolUse *struct {
527 ToolUseID string `json:"toolUseId"`
528 Name string `json:"name"`
529 } `json:"toolUse"`
530 } `json:"start"`
531 }
532 if err := unmarshalBedrockEventPayload(evt.payload, "contentBlockStart", &d); err != nil {
533 continue
534 }
535 st := &bedrockBlockState{}
536 contentBlocks[d.ContentBlockIndex] = st
537 if d.Start.ToolUse != nil {
538 st.isToolUse = true
539 st.toolID = d.Start.ToolUse.ToolUseID
540 st.toolName = d.Start.ToolUse.Name
541 out <- EventToolStart{ID: st.toolID, Name: st.toolName}
542 }
543 case "contentBlockDelta":
544 var d struct {
545 ContentBlockIndex int `json:"contentBlockIndex"`
546 Delta struct {
547 Text string `json:"text"`
548 ToolUse *struct {
549 Input string `json:"input"`
550 } `json:"toolUse"`
551 } `json:"delta"`
552 }
553 if err := unmarshalBedrockEventPayload(evt.payload, "contentBlockDelta", &d); err != nil {
554 continue
555 }
556 st := contentBlocks[d.ContentBlockIndex]
557 if st == nil {
558 st = &bedrockBlockState{}
559 contentBlocks[d.ContentBlockIndex] = st
560 }
561 if d.Delta.Text != "" {
562 st.text.WriteString(d.Delta.Text)
563 out <- EventTextDelta{Delta: d.Delta.Text}
564 }
565 if d.Delta.ToolUse != nil && d.Delta.ToolUse.Input != "" {
566 st.toolArgs.WriteString(d.Delta.ToolUse.Input)
567 out <- EventToolArgs{ID: st.toolID, Delta: d.Delta.ToolUse.Input}
568 }
569 case "contentBlockStop":
570 var d struct {
571 ContentBlockIndex int `json:"contentBlockIndex"`
572 }
573 if err := unmarshalBedrockEventPayload(evt.payload, "contentBlockStop", &d); err != nil {
574 continue
575 }
576 st := contentBlocks[d.ContentBlockIndex]
577 if st == nil {
578 continue
579 }
580 if st.isToolUse {
581 args := st.toolArgs.String()
582 if args == "" {
583 args = "{}"
584 }
585 finalMsg.Content = append(finalMsg.Content, ToolCallBlock{
586 ID: st.toolID, Name: st.toolName, Arguments: json.RawMessage(args),
587 })
588 out <- EventToolEnd{ID: st.toolID}
589 } else if st.text.Len() > 0 {
590 finalMsg.Content = append(finalMsg.Content, TextBlock{Text: st.text.String()})
591 }
592 case "messageStop":
593 var d struct {
594 StopReason string `json:"stopReason"`
595 }
596 _ = unmarshalBedrockEventPayload(evt.payload, "messageStop", &d)
597 switch d.StopReason {
598 case "tool_use":
599 stop = StopToolUse
600 case "end_turn":
601 stop = StopEnd
602 case "max_tokens":
603 stop = StopLength
604 default:
605 stop = StopEnd
606 }
607 case "metadata":
608 var d struct {
609 Usage struct {
610 InputTokens int `json:"inputTokens"`
611 OutputTokens int `json:"outputTokens"`
612 CacheReadInputTokens int `json:"cacheReadInputTokens"`
613 CacheWriteInputTokens int `json:"cacheWriteInputTokens"`
614 } `json:"usage"`
615 }
616 if err := unmarshalBedrockEventPayload(evt.payload, "metadata", &d); err == nil {
617 usage.InputTokens = d.Usage.InputTokens
618 usage.OutputTokens = d.Usage.OutputTokens
619 usage.CacheReadTokens = d.Usage.CacheReadInputTokens
620 usage.CacheWriteTokens = d.Usage.CacheWriteInputTokens
621 if m, err := FindModel("amazon-bedrock", req.Model); err == nil {
622 usage.CostUSD = ComputeCost(m, usage)
623 }
624 out <- EventUsage{Usage: usage}
625 }
626 }
627 }
628 out <- EventDone{Stop: stop, Message: finalMsg}
629}
630
631type bedrockBlockState struct {
632 isToolUse bool
633 toolID string
634 toolName string
635 toolArgs strings.Builder
636 text strings.Builder
637}
638
639func bedrockEventTypeFromPayload(payload []byte) string {
640 var outer map[string]json.RawMessage
641 if err := json.Unmarshal(payload, &outer); err != nil {
642 return ""
643 }
644 for _, name := range []string{"messageStart", "contentBlockStart", "contentBlockDelta", "contentBlockStop", "messageStop", "metadata"} {
645 if _, ok := outer[name]; ok {
646 return name
647 }
648 }
649 return ""
650}
651
652func unmarshalBedrockEventPayload(payload []byte, eventType string, dst any) error {
653 var outer map[string]json.RawMessage
654 if err := json.Unmarshal(payload, &outer); err == nil {
655 if wrapped, ok := outer[eventType]; ok {
656 return json.Unmarshal(wrapped, dst)
657 }
658 }
659 if err := json.Unmarshal(payload, dst); err != nil {
660 return fmt.Errorf("bedrock: parse %s payload: %w", eventType, err)
661 }
662 return nil
663}
664
665// ---- event-stream binary framing parser ----
666
667type eventStreamMessage struct {
668 headers map[string]string
669 payload []byte
670}
671
672func (m *eventStreamMessage) headerString(name string) string { return m.headers[name] }
673
674// readEventStreamMessage reads one event-stream message from r. Returns
675// io.EOF when the stream is finished cleanly.
676func readEventStreamMessage(r io.Reader) (*eventStreamMessage, error) {
677 var prelude [8]byte
678 if _, err := io.ReadFull(r, prelude[:]); err != nil {
679 return nil, err
680 }
681 totalLen := binary.BigEndian.Uint32(prelude[0:4])
682 headersLen := binary.BigEndian.Uint32(prelude[4:8])
683 if totalLen < 16 || headersLen > totalLen-16 {
684 return nil, fmt.Errorf("bedrock: malformed event-stream prelude (total=%d headers=%d)", totalLen, headersLen)
685 }
686 // Skip prelude CRC (4 bytes); we don't validate.
687 var preludeCRC [4]byte
688 if _, err := io.ReadFull(r, preludeCRC[:]); err != nil {
689 return nil, err
690 }
691 headersBuf := make([]byte, headersLen)
692 if _, err := io.ReadFull(r, headersBuf); err != nil {
693 return nil, err
694 }
695 payloadLen := int(totalLen) - 16 - int(headersLen)
696 payload := make([]byte, payloadLen)
697 if _, err := io.ReadFull(r, payload); err != nil {
698 return nil, err
699 }
700 var trailer [4]byte
701 if _, err := io.ReadFull(r, trailer[:]); err != nil {
702 return nil, err
703 }
704 // Parse headers.
705 hdrs := map[string]string{}
706 i := 0
707 for i < len(headersBuf) {
708 if i+1 > len(headersBuf) {
709 break
710 }
711 nameLen := int(headersBuf[i])
712 i++
713 if i+nameLen > len(headersBuf) {
714 return nil, fmt.Errorf("bedrock: header name overflow")
715 }
716 name := string(headersBuf[i : i+nameLen])
717 i += nameLen
718 if i+1 > len(headersBuf) {
719 return nil, fmt.Errorf("bedrock: header value-type missing")
720 }
721 valueType := headersBuf[i]
722 i++
723 // Type 7 = string with 2-byte length. Type 6 = byte-array similar.
724 // Other types (bool/int/long/timestamp/uuid) we treat as opaque
725 // strings since bedrock's event-type headers are always type 7.
726 switch valueType {
727 case 7, 6:
728 if i+2 > len(headersBuf) {
729 return nil, fmt.Errorf("bedrock: header value length missing")
730 }
731 vLen := int(binary.BigEndian.Uint16(headersBuf[i : i+2]))
732 i += 2
733 if i+vLen > len(headersBuf) {
734 return nil, fmt.Errorf("bedrock: header value overflow")
735 }
736 hdrs[name] = string(headersBuf[i : i+vLen])
737 i += vLen
738 case 0: // bool true
739 hdrs[name] = "true"
740 case 1: // bool false
741 hdrs[name] = "false"
742 case 2: // byte
743 if i+1 > len(headersBuf) {
744 return nil, fmt.Errorf("bedrock: header byte missing")
745 }
746 i++
747 case 3: // int16
748 if i+2 > len(headersBuf) {
749 return nil, fmt.Errorf("bedrock: header int16 missing")
750 }
751 i += 2
752 case 4: // int32
753 if i+4 > len(headersBuf) {
754 return nil, fmt.Errorf("bedrock: header int32 missing")
755 }
756 i += 4
757 case 5: // int64
758 if i+8 > len(headersBuf) {
759 return nil, fmt.Errorf("bedrock: header int64 missing")
760 }
761 i += 8
762 case 8: // timestamp (int64)
763 if i+8 > len(headersBuf) {
764 return nil, fmt.Errorf("bedrock: header timestamp missing")
765 }
766 i += 8
767 case 9: // uuid (16 bytes)
768 if i+16 > len(headersBuf) {
769 return nil, fmt.Errorf("bedrock: header uuid missing")
770 }
771 i += 16
772 default:
773 return nil, fmt.Errorf("bedrock: unknown header value-type %d", valueType)
774 }
775 }
776 return &eventStreamMessage{headers: hdrs, payload: payload}, nil
777}
778
779// ---- SigV4 signing ----
780//
781// AWS Signature Version 4. Implemented from scratch so we don't pull in
782// aws-sdk-go-v2 (large transitive dep tree just for one signer). The
783// algorithm is documented at:
784// https://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html
785//
786// Steps:
787//
788// 1. Build the canonical request: method + path + canonical query +
789// canonical headers + signed headers + payload-hash.
790// 2. Build the string-to-sign: algorithm + amz-date + credential scope +
791// sha256(canonical request).
792// 3. Derive the signing key by chaining HMAC-SHA256:
793// kSecret -> kDate -> kRegion -> kService -> kSigning
794// 4. signature = HMAC-SHA256(kSigning, stringToSign)
795// 5. Authorization header: AWS4-HMAC-SHA256 Credential=..., SignedHeaders=..., Signature=...
796//
797// Payload hash is sha256 of the JSON body. For Bedrock's streaming
798// endpoint this works because the request body is fully buffered before
799// the call — we don't need the streaming-payload variant.
800
801func sigHMAC(key, msg []byte) []byte {
802 m := hmac.New(sha256.New, key)
803 m.Write(msg)
804 return m.Sum(nil)
805}
806
807func sigSHA256Hex(b []byte) string {
808 h := sha256.Sum256(b)
809 return hex.EncodeToString(h[:])
810}
811
812func signSigV4(req *http.Request, payload []byte, service, region string, creds *bedrockSigV4Creds, now time.Time) error {
813 amzDate := now.Format("20060102T150405Z")
814 shortDate := now.Format("20060102")
815 credentialScope := shortDate + "/" + region + "/" + service + "/aws4_request"
816
817 // Required headers.
818 req.Header.Set("host", req.URL.Host)
819 req.Header.Set("x-amz-date", amzDate)
820 if creds.sessionToken != "" {
821 req.Header.Set("x-amz-security-token", creds.sessionToken)
822 }
823 payloadHash := sigSHA256Hex(payload)
824 req.Header.Set("x-amz-content-sha256", payloadHash)
825
826 // Canonical headers: lowercase name, trimmed value, sorted by name,
827 // each on its own line ending with \n.
828 var names []string
829 values := map[string]string{}
830 for k, vs := range req.Header {
831 lower := strings.ToLower(k)
832 // Skip authorization (we're computing it) and any
833 // connection-specific headers.
834 if lower == "authorization" {
835 continue
836 }
837 names = append(names, lower)
838 values[lower] = strings.Join(vs, ",")
839 }
840 // host is special — it's not in req.Header by default; set above.
841 sort.Strings(names)
842 var canonHdrs strings.Builder
843 for _, n := range names {
844 canonHdrs.WriteString(n)
845 canonHdrs.WriteByte(':')
846 canonHdrs.WriteString(strings.TrimSpace(values[n]))
847 canonHdrs.WriteByte('\n')
848 }
849 signedHeaders := strings.Join(names, ";")
850
851 // Canonical query string: keys sorted by name, each key and value
852 // URI-escaped (RFC 3986).
853 q := req.URL.Query()
854 var qKeys []string
855 for k := range q {
856 qKeys = append(qKeys, k)
857 }
858 sort.Strings(qKeys)
859 var canonQuery strings.Builder
860 for i, k := range qKeys {
861 if i > 0 {
862 canonQuery.WriteByte('&')
863 }
864 canonQuery.WriteString(url.QueryEscape(k))
865 canonQuery.WriteByte('=')
866 canonQuery.WriteString(url.QueryEscape(q.Get(k)))
867 }
868
869 // Canonical request.
870 canonReq := req.Method + "\n" +
871 canonicalSigV4Path(req.URL.Path) + "\n" +
872 canonQuery.String() + "\n" +
873 canonHdrs.String() + "\n" +
874 signedHeaders + "\n" +
875 payloadHash
876
877 // String to sign.
878 stringToSign := "AWS4-HMAC-SHA256\n" + amzDate + "\n" + credentialScope + "\n" + sigSHA256Hex([]byte(canonReq))
879
880 // Signing key.
881 kDate := sigHMAC([]byte("AWS4"+creds.secretAccessKey), []byte(shortDate))
882 kRegion := sigHMAC(kDate, []byte(region))
883 kService := sigHMAC(kRegion, []byte(service))
884 kSigning := sigHMAC(kService, []byte("aws4_request"))
885
886 // Signature.
887 signature := hex.EncodeToString(sigHMAC(kSigning, []byte(stringToSign)))
888
889 // Authorization header.
890 auth := "AWS4-HMAC-SHA256 " +
891 "Credential=" + creds.accessKeyID + "/" + credentialScope + ", " +
892 "SignedHeaders=" + signedHeaders + ", " +
893 "Signature=" + signature
894 req.Header.Set("Authorization", auth)
895 return nil
896}
897
898// canonicalSigV4Path returns the path with each segment URI-encoded
899// according to SigV4 rules (everything except unreserved chars
900// A-Za-z0-9-_.~ and / between segments). Bedrock model IDs contain
901// dots, colons, and slashes; the colons must be percent-encoded.
902func canonicalSigV4Path(p string) string {
903 if p == "" {
904 return "/"
905 }
906 segments := strings.Split(p, "/")
907 for i, s := range segments {
908 segments[i] = sigV4EncodeSegment(s)
909 }
910 return strings.Join(segments, "/")
911}
912
913func sigV4EncodeSegment(s string) string {
914 var b strings.Builder
915 for i := 0; i < len(s); i++ {
916 c := s[i]
917 // Unreserved per RFC 3986.
918 if (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
919 c == '-' || c == '_' || c == '.' || c == '~' {
920 b.WriteByte(c)
921 continue
922 }
923 fmt.Fprintf(&b, "%%%02X", c)
924 }
925 return b.String()
926}