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 (c *bedrockClient) buildRequest(req Request) (*bedrockRequest, error) {
220 out := &bedrockRequest{}
221 if req.System != "" {
222 out.System = []map[string]string{{"text": req.System}}
223 }
224 out.InferenceConfig.Temperature = req.Temperature
225 out.InferenceConfig.MaxTokens = req.MaxTokens
226 if out.InferenceConfig.MaxTokens == 0 {
227 out.InferenceConfig.MaxTokens = 4096
228 }
229 for _, m := range req.Messages {
230 role := string(m.Role)
231 if role == "tool" {
232 role = "user"
233 }
234 bm := bedrockMessage{Role: role}
235 for _, c := range m.Content {
236 switch v := c.(type) {
237 case TextBlock:
238 bm.Content = append(bm.Content, map[string]interface{}{"text": v.Text})
239 case ToolCallBlock:
240 var input map[string]interface{}
241 _ = json.Unmarshal(v.Arguments, &input)
242 if input == nil {
243 input = map[string]interface{}{}
244 }
245 bm.Content = append(bm.Content, map[string]interface{}{
246 "toolUse": map[string]interface{}{
247 "toolUseId": v.ID, "name": v.Name, "input": input,
248 },
249 })
250 case ToolResultBlock:
251 var resultContent []map[string]interface{}
252 for _, inner := range v.Content {
253 if tb, ok := inner.(TextBlock); ok {
254 resultContent = append(resultContent, map[string]interface{}{"text": tb.Text})
255 }
256 }
257 status := "success"
258 if v.IsError {
259 status = "error"
260 }
261 bm.Content = append(bm.Content, map[string]interface{}{
262 "toolResult": map[string]interface{}{
263 "toolUseId": v.CallID,
264 "content": resultContent,
265 "status": status,
266 },
267 })
268 }
269 }
270 out.Messages = append(out.Messages, bm)
271 }
272 if len(req.Tools) > 0 {
273 tc := struct {
274 Tools []bedrockToolSpec `json:"tools"`
275 }{}
276 for _, t := range req.Tools {
277 var ts bedrockToolSpec
278 ts.ToolSpec.Name = t.Name
279 ts.ToolSpec.Description = t.Description
280 ts.ToolSpec.InputSchema.JSON = t.Schema
281 tc.Tools = append(tc.Tools, ts)
282 }
283 out.ToolConfig = &tc
284 }
285 return out, nil
286}
287
288func (c *bedrockClient) Stream(ctx context.Context, req Request) (<-chan Event, error) {
289 wire, err := c.buildRequest(req)
290 if err != nil {
291 return nil, err
292 }
293 body, err := json.Marshal(wire)
294 if err != nil {
295 return nil, err
296 }
297 url := c.baseURL + "/model/" + req.Model + "/converse-stream"
298 httpReq, err := http.NewRequestWithContext(ctx, "POST", url, bytes.NewReader(body))
299 if err != nil {
300 return nil, err
301 }
302 httpReq.Header.Set("content-type", "application/json")
303 httpReq.Header.Set("accept", "application/vnd.amazon.eventstream")
304 if c.bearerToken != "" {
305 httpReq.Header.Set("authorization", "Bearer "+c.bearerToken)
306 } else if c.sigv4 != nil {
307 if err := signSigV4(httpReq, body, "bedrock", c.region, c.sigv4, time.Now().UTC()); err != nil {
308 return nil, fmt.Errorf("bedrock: sigv4 sign: %w", err)
309 }
310 } else {
311 return nil, fmt.Errorf("bedrock: no auth configured")
312 }
313 resp, err := c.http.Do(httpReq)
314 if err != nil {
315 return nil, fmt.Errorf("bedrock: %w", err)
316 }
317 if resp.StatusCode != http.StatusOK {
318 b, _ := io.ReadAll(resp.Body)
319 resp.Body.Close()
320 return nil, fmt.Errorf("bedrock: http %d: %s", resp.StatusCode, strings.TrimSpace(string(b)))
321 }
322 out := make(chan Event, 16)
323 go c.runStream(ctx, resp, req, out)
324 return out, nil
325}
326
327func (c *bedrockClient) runStream(ctx context.Context, resp *http.Response, req Request, out chan<- Event) {
328 defer close(out)
329 defer resp.Body.Close()
330
331 out <- EventStart{Provider: "amazon-bedrock", Model: req.Model}
332
333 // State accumulated across deltas.
334 contentBlocks := map[int]*bedrockBlockState{}
335 stop := StopEnd
336 finalMsg := Message{Role: RoleAssistant, Time: time.Now()}
337 var usage Usage
338
339 for {
340 if ctx.Err() != nil {
341 stop = StopAborted
342 break
343 }
344 evt, err := readEventStreamMessage(resp.Body)
345 if err != nil {
346 if err == io.EOF {
347 break
348 }
349 out <- EventDone{Stop: StopError, Err: err, Message: finalMsg}
350 return
351 }
352 eventType := evt.headerString(":event-type")
353 messageType := evt.headerString(":message-type")
354 if messageType == "exception" {
355 out <- EventDone{Stop: StopError, Err: fmt.Errorf("bedrock exception (%s): %s", evt.headerString(":exception-type"), string(evt.payload)), Message: finalMsg}
356 return
357 }
358 switch eventType {
359 case "messageStart":
360 // nothing to do; role is always "assistant"
361 case "contentBlockStart":
362 var d struct {
363 ContentBlockIndex int `json:"contentBlockIndex"`
364 Start struct {
365 ToolUse *struct {
366 ToolUseID string `json:"toolUseId"`
367 Name string `json:"name"`
368 } `json:"toolUse"`
369 } `json:"start"`
370 }
371 if err := json.Unmarshal(evt.payload, &d); err != nil {
372 continue
373 }
374 st := &bedrockBlockState{}
375 contentBlocks[d.ContentBlockIndex] = st
376 if d.Start.ToolUse != nil {
377 st.isToolUse = true
378 st.toolID = d.Start.ToolUse.ToolUseID
379 st.toolName = d.Start.ToolUse.Name
380 out <- EventToolStart{ID: st.toolID, Name: st.toolName}
381 }
382 case "contentBlockDelta":
383 var d struct {
384 ContentBlockIndex int `json:"contentBlockIndex"`
385 Delta struct {
386 Text string `json:"text"`
387 ToolUse *struct {
388 Input string `json:"input"`
389 } `json:"toolUse"`
390 } `json:"delta"`
391 }
392 if err := json.Unmarshal(evt.payload, &d); err != nil {
393 continue
394 }
395 st := contentBlocks[d.ContentBlockIndex]
396 if st == nil {
397 continue
398 }
399 if d.Delta.Text != "" {
400 st.text.WriteString(d.Delta.Text)
401 out <- EventTextDelta{Delta: d.Delta.Text}
402 }
403 if d.Delta.ToolUse != nil && d.Delta.ToolUse.Input != "" {
404 st.toolArgs.WriteString(d.Delta.ToolUse.Input)
405 out <- EventToolArgs{ID: st.toolID, Delta: d.Delta.ToolUse.Input}
406 }
407 case "contentBlockStop":
408 var d struct {
409 ContentBlockIndex int `json:"contentBlockIndex"`
410 }
411 if err := json.Unmarshal(evt.payload, &d); err != nil {
412 continue
413 }
414 st := contentBlocks[d.ContentBlockIndex]
415 if st == nil {
416 continue
417 }
418 if st.isToolUse {
419 args := st.toolArgs.String()
420 if args == "" {
421 args = "{}"
422 }
423 finalMsg.Content = append(finalMsg.Content, ToolCallBlock{
424 ID: st.toolID, Name: st.toolName, Arguments: json.RawMessage(args),
425 })
426 out <- EventToolEnd{ID: st.toolID}
427 } else if st.text.Len() > 0 {
428 finalMsg.Content = append(finalMsg.Content, TextBlock{Text: st.text.String()})
429 }
430 case "messageStop":
431 var d struct {
432 StopReason string `json:"stopReason"`
433 }
434 _ = json.Unmarshal(evt.payload, &d)
435 switch d.StopReason {
436 case "tool_use":
437 stop = StopToolUse
438 case "end_turn":
439 stop = StopEnd
440 case "max_tokens":
441 stop = StopLength
442 default:
443 stop = StopEnd
444 }
445 case "metadata":
446 var d struct {
447 Usage struct {
448 InputTokens int `json:"inputTokens"`
449 OutputTokens int `json:"outputTokens"`
450 CacheReadInputTokens int `json:"cacheReadInputTokens"`
451 CacheWriteInputTokens int `json:"cacheWriteInputTokens"`
452 } `json:"usage"`
453 }
454 if err := json.Unmarshal(evt.payload, &d); err == nil {
455 usage.InputTokens = d.Usage.InputTokens
456 usage.OutputTokens = d.Usage.OutputTokens
457 usage.CacheReadTokens = d.Usage.CacheReadInputTokens
458 usage.CacheWriteTokens = d.Usage.CacheWriteInputTokens
459 if m, err := FindModel("amazon-bedrock", req.Model); err == nil {
460 usage.CostUSD = ComputeCost(m, usage)
461 }
462 out <- EventUsage{Usage: usage}
463 }
464 }
465 }
466 out <- EventDone{Stop: stop, Message: finalMsg}
467}
468
469type bedrockBlockState struct {
470 isToolUse bool
471 toolID string
472 toolName string
473 toolArgs strings.Builder
474 text strings.Builder
475}
476
477// ---- event-stream binary framing parser ----
478
479type eventStreamMessage struct {
480 headers map[string]string
481 payload []byte
482}
483
484func (m *eventStreamMessage) headerString(name string) string { return m.headers[name] }
485
486// readEventStreamMessage reads one event-stream message from r. Returns
487// io.EOF when the stream is finished cleanly.
488func readEventStreamMessage(r io.Reader) (*eventStreamMessage, error) {
489 var prelude [8]byte
490 if _, err := io.ReadFull(r, prelude[:]); err != nil {
491 return nil, err
492 }
493 totalLen := binary.BigEndian.Uint32(prelude[0:4])
494 headersLen := binary.BigEndian.Uint32(prelude[4:8])
495 if totalLen < 16 || headersLen > totalLen-16 {
496 return nil, fmt.Errorf("bedrock: malformed event-stream prelude (total=%d headers=%d)", totalLen, headersLen)
497 }
498 // Skip prelude CRC (4 bytes); we don't validate.
499 var preludeCRC [4]byte
500 if _, err := io.ReadFull(r, preludeCRC[:]); err != nil {
501 return nil, err
502 }
503 headersBuf := make([]byte, headersLen)
504 if _, err := io.ReadFull(r, headersBuf); err != nil {
505 return nil, err
506 }
507 payloadLen := int(totalLen) - 16 - int(headersLen)
508 payload := make([]byte, payloadLen)
509 if _, err := io.ReadFull(r, payload); err != nil {
510 return nil, err
511 }
512 var trailer [4]byte
513 if _, err := io.ReadFull(r, trailer[:]); err != nil {
514 return nil, err
515 }
516 // Parse headers.
517 hdrs := map[string]string{}
518 i := 0
519 for i < len(headersBuf) {
520 if i+1 > len(headersBuf) {
521 break
522 }
523 nameLen := int(headersBuf[i])
524 i++
525 if i+nameLen > len(headersBuf) {
526 return nil, fmt.Errorf("bedrock: header name overflow")
527 }
528 name := string(headersBuf[i : i+nameLen])
529 i += nameLen
530 if i+1 > len(headersBuf) {
531 return nil, fmt.Errorf("bedrock: header value-type missing")
532 }
533 valueType := headersBuf[i]
534 i++
535 // Type 7 = string with 2-byte length. Type 6 = byte-array similar.
536 // Other types (bool/int/long/timestamp/uuid) we treat as opaque
537 // strings since bedrock's event-type headers are always type 7.
538 switch valueType {
539 case 7, 6:
540 if i+2 > len(headersBuf) {
541 return nil, fmt.Errorf("bedrock: header value length missing")
542 }
543 vLen := int(binary.BigEndian.Uint16(headersBuf[i : i+2]))
544 i += 2
545 if i+vLen > len(headersBuf) {
546 return nil, fmt.Errorf("bedrock: header value overflow")
547 }
548 hdrs[name] = string(headersBuf[i : i+vLen])
549 i += vLen
550 case 0: // bool true
551 hdrs[name] = "true"
552 case 1: // bool false
553 hdrs[name] = "false"
554 case 2: // byte
555 if i+1 > len(headersBuf) {
556 return nil, fmt.Errorf("bedrock: header byte missing")
557 }
558 i++
559 case 3: // int16
560 if i+2 > len(headersBuf) {
561 return nil, fmt.Errorf("bedrock: header int16 missing")
562 }
563 i += 2
564 case 4: // int32
565 if i+4 > len(headersBuf) {
566 return nil, fmt.Errorf("bedrock: header int32 missing")
567 }
568 i += 4
569 case 5: // int64
570 if i+8 > len(headersBuf) {
571 return nil, fmt.Errorf("bedrock: header int64 missing")
572 }
573 i += 8
574 case 8: // timestamp (int64)
575 if i+8 > len(headersBuf) {
576 return nil, fmt.Errorf("bedrock: header timestamp missing")
577 }
578 i += 8
579 case 9: // uuid (16 bytes)
580 if i+16 > len(headersBuf) {
581 return nil, fmt.Errorf("bedrock: header uuid missing")
582 }
583 i += 16
584 default:
585 return nil, fmt.Errorf("bedrock: unknown header value-type %d", valueType)
586 }
587 }
588 return &eventStreamMessage{headers: hdrs, payload: payload}, nil
589}
590
591// ---- SigV4 signing ----
592//
593// AWS Signature Version 4. Implemented from scratch so we don't pull in
594// aws-sdk-go-v2 (large transitive dep tree just for one signer). The
595// algorithm is documented at:
596// https://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html
597//
598// Steps:
599//
600// 1. Build the canonical request: method + path + canonical query +
601// canonical headers + signed headers + payload-hash.
602// 2. Build the string-to-sign: algorithm + amz-date + credential scope +
603// sha256(canonical request).
604// 3. Derive the signing key by chaining HMAC-SHA256:
605// kSecret -> kDate -> kRegion -> kService -> kSigning
606// 4. signature = HMAC-SHA256(kSigning, stringToSign)
607// 5. Authorization header: AWS4-HMAC-SHA256 Credential=..., SignedHeaders=..., Signature=...
608//
609// Payload hash is sha256 of the JSON body. For Bedrock's streaming
610// endpoint this works because the request body is fully buffered before
611// the call — we don't need the streaming-payload variant.
612
613func sigHMAC(key, msg []byte) []byte {
614 m := hmac.New(sha256.New, key)
615 m.Write(msg)
616 return m.Sum(nil)
617}
618
619func sigSHA256Hex(b []byte) string {
620 h := sha256.Sum256(b)
621 return hex.EncodeToString(h[:])
622}
623
624func signSigV4(req *http.Request, payload []byte, service, region string, creds *bedrockSigV4Creds, now time.Time) error {
625 amzDate := now.Format("20060102T150405Z")
626 shortDate := now.Format("20060102")
627 credentialScope := shortDate + "/" + region + "/" + service + "/aws4_request"
628
629 // Required headers.
630 req.Header.Set("host", req.URL.Host)
631 req.Header.Set("x-amz-date", amzDate)
632 if creds.sessionToken != "" {
633 req.Header.Set("x-amz-security-token", creds.sessionToken)
634 }
635 payloadHash := sigSHA256Hex(payload)
636 req.Header.Set("x-amz-content-sha256", payloadHash)
637
638 // Canonical headers: lowercase name, trimmed value, sorted by name,
639 // each on its own line ending with \n.
640 var names []string
641 values := map[string]string{}
642 for k, vs := range req.Header {
643 lower := strings.ToLower(k)
644 // Skip authorization (we're computing it) and any
645 // connection-specific headers.
646 if lower == "authorization" {
647 continue
648 }
649 names = append(names, lower)
650 values[lower] = strings.Join(vs, ",")
651 }
652 // host is special — it's not in req.Header by default; set above.
653 sort.Strings(names)
654 var canonHdrs strings.Builder
655 for _, n := range names {
656 canonHdrs.WriteString(n)
657 canonHdrs.WriteByte(':')
658 canonHdrs.WriteString(strings.TrimSpace(values[n]))
659 canonHdrs.WriteByte('\n')
660 }
661 signedHeaders := strings.Join(names, ";")
662
663 // Canonical query string: keys sorted by name, each key and value
664 // URI-escaped (RFC 3986).
665 q := req.URL.Query()
666 var qKeys []string
667 for k := range q {
668 qKeys = append(qKeys, k)
669 }
670 sort.Strings(qKeys)
671 var canonQuery strings.Builder
672 for i, k := range qKeys {
673 if i > 0 {
674 canonQuery.WriteByte('&')
675 }
676 canonQuery.WriteString(url.QueryEscape(k))
677 canonQuery.WriteByte('=')
678 canonQuery.WriteString(url.QueryEscape(q.Get(k)))
679 }
680
681 // Canonical request.
682 canonReq := req.Method + "\n" +
683 canonicalSigV4Path(req.URL.Path) + "\n" +
684 canonQuery.String() + "\n" +
685 canonHdrs.String() + "\n" +
686 signedHeaders + "\n" +
687 payloadHash
688
689 // String to sign.
690 stringToSign := "AWS4-HMAC-SHA256\n" + amzDate + "\n" + credentialScope + "\n" + sigSHA256Hex([]byte(canonReq))
691
692 // Signing key.
693 kDate := sigHMAC([]byte("AWS4"+creds.secretAccessKey), []byte(shortDate))
694 kRegion := sigHMAC(kDate, []byte(region))
695 kService := sigHMAC(kRegion, []byte(service))
696 kSigning := sigHMAC(kService, []byte("aws4_request"))
697
698 // Signature.
699 signature := hex.EncodeToString(sigHMAC(kSigning, []byte(stringToSign)))
700
701 // Authorization header.
702 auth := "AWS4-HMAC-SHA256 " +
703 "Credential=" + creds.accessKeyID + "/" + credentialScope + ", " +
704 "SignedHeaders=" + signedHeaders + ", " +
705 "Signature=" + signature
706 req.Header.Set("Authorization", auth)
707 return nil
708}
709
710// canonicalSigV4Path returns the path with each segment URI-encoded
711// according to SigV4 rules (everything except unreserved chars
712// A-Za-z0-9-_.~ and / between segments). Bedrock model IDs contain
713// dots, colons, and slashes; the colons must be percent-encoded.
714func canonicalSigV4Path(p string) string {
715 if p == "" {
716 return "/"
717 }
718 segments := strings.Split(p, "/")
719 for i, s := range segments {
720 segments[i] = sigV4EncodeSegment(s)
721 }
722 return strings.Join(segments, "/")
723}
724
725func sigV4EncodeSegment(s string) string {
726 var b strings.Builder
727 for i := 0; i < len(s); i++ {
728 c := s[i]
729 // Unreserved per RFC 3986.
730 if (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
731 c == '-' || c == '_' || c == '.' || c == '~' {
732 b.WriteByte(c)
733 continue
734 }
735 fmt.Fprintf(&b, "%%%02X", c)
736 }
737 return b.String()
738}