internal/ai/llm/openai/openai.go

@@ -54,7 +54,9 @@ type Config struct {
 	// need it.
 	Model string
 	// Headers are extra request headers, e.g. OpenRouter's HTTP-Referer and
-	// X-Title. They must not set Authorization or Content-Type.
+	// X-Title. An Accept header replaces the default "application/json".
+	// Headers the adapter or net/http set themselves (see managedHeaders)
+	// are rejected.
 	Headers map[string]string
 	// StructuredOutput is how JSON is requested when a Request has a Schema.
 	StructuredOutput StructuredOutput
@@ -91,17 +93,24 @@ func New(cfg Config) (*Provider, error) {
 	default:
 		return nil, fmt.Errorf("openai: unknown structured output mode %q", cfg.StructuredOutput)
 	}
-	headers := make(http.Header, len(cfg.Headers))
+	headers := make(http.Header, len(cfg.Headers)+1)
 	for name, value := range cfg.Headers {
+		// Values are never echoed: one may carry a credential.
+		if !validHeaderName(name) {
+			return nil, fmt.Errorf("openai: extra header name %q is not a valid HTTP token", name)
+		}
 		canonical := textproto.CanonicalMIMEHeaderKey(name)
-		if canonical == "Authorization" || canonical == "Content-Type" {
+		if managedHeaders[canonical] {
 			return nil, fmt.Errorf("openai: extra header %q is set by the adapter", canonical)
 		}
-		if name == "" || strings.ContainsAny(name, " \t\r\n:") || strings.ContainsAny(value, "\r\n") {
-			return nil, fmt.Errorf("openai: extra header %q is malformed", name)
+		if !validHeaderValue(value) {
+			return nil, fmt.Errorf("openai: extra header %q has a control character in its value", canonical)
 		}
 		headers.Set(canonical, value)
 	}
+	if headers.Get("Accept") == "" {
+		headers.Set("Accept", "application/json")
+	}
 	return &Provider{
 		base:    strings.TrimRight(cfg.BaseURL, "/"),
 		apiKey:  cfg.APIKey,
@@ -112,6 +121,46 @@ func New(cfg Config) (*Provider, error) {
 	}, nil
 }
 
+// managedHeaders are the request headers the adapter or net/http set; a
+// configured value for one would be overwritten or ignored.
+var managedHeaders = map[string]bool{
+	"Authorization":     true,
+	"Content-Type":      true,
+	"Content-Length":    true,
+	"Transfer-Encoding": true,
+	"Host":              true,
+	"Connection":        true,
+}
+
+// validHeaderName reports whether name is an RFC 9110 field-name: a
+// non-empty token of letters, digits and !#$%&'*+-.^_`|~.
+func validHeaderName(name string) bool {
+	if name == "" {
+		return false
+	}
+	for i := 0; i < len(name); i++ {
+		c := name[i]
+		switch {
+		case 'a' <= c && c <= 'z', 'A' <= c && c <= 'Z', '0' <= c && c <= '9':
+		case strings.IndexByte("!#$%&'*+-.^_`|~", c) >= 0:
+		default:
+			return false
+		}
+	}
+	return true
+}
+
+// validHeaderValue reports whether value is an RFC 9110 field-value: no
+// control characters other than horizontal tab, so no CR, LF or DEL.
+func validHeaderValue(value string) bool {
+	for i := 0; i < len(value); i++ {
+		if c := value[i]; (c < 0x20 && c != '\t') || c == 0x7f {
+			return false
+		}
+	}
+	return true
+}
+
 // maxResponseBody caps a successful response body; a larger one is an error.
 const maxResponseBody = 16 << 20
 
@@ -339,7 +388,6 @@ func (p *Provider) do(ctx context.Context, method, path string, payload []byte)
 	if payload != nil {
 		httpReq.Header.Set("Content-Type", "application/json")
 	}
-	httpReq.Header.Set("Accept", "application/json")
 	if p.apiKey != "" {
 		httpReq.Header.Set("Authorization", "Bearer "+p.apiKey)
 	}

internal/ai/llm/openai/openai_test.go

@@ -619,6 +619,40 @@ func TestGenerateRejectsInvalidRequests(t *testing.T) {
 	}
 }
 
+func TestNewRejectsBadHeaderWithoutEchoingValue(t *testing.T) {
+	_, err := New(Config{BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Title": testKey + "\u0019"}})
+	if err == nil {
+		t.Fatal("New() = nil error")
+	}
+	assertNoSecret(t, err)
+}
+
+func TestAcceptHeader(t *testing.T) {
+	for name, tc := range map[string]struct {
+		headers map[string]string
+		want    string
+	}{
+		"default":    {nil, "application/json"},
+		"configured": {map[string]string{"accept": "application/json, text/event-stream"}, "application/json, text/event-stream"},
+	} {
+		vs := newVendorServer(t, reply{status: 200, fixture: "openai_models.json"})
+		p := newProvider(t, vs.URL+"/v1", JSONSchema, tc.headers)
+		if _, err := p.ListModels(context.Background()); err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+		if got := vs.only(t).header.Values("Accept"); len(got) != 1 || got[0] != tc.want {
+			t.Errorf("%s: Accept = %q, want %q", name, got, tc.want)
+		}
+	}
+}
+
+func TestNewAcceptsValidHeaders(t *testing.T) {
+	headers := map[string]string{"X-Trace_ID.v2!#$%&'*+^`|~": "tab\tand obs-text \xe2\x9c\x93", "X-Empty": ""}
+	if _, err := New(Config{BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: headers}); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestNewRejectsBadConfig(t *testing.T) {
 	cases := map[string]Config{
 		"empty base":         {StructuredOutput: JSONSchema},
@@ -636,6 +670,15 @@ func TestNewRejectsBadConfig(t *testing.T) {
 		"content-type hdr":   {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"Content-Type": "text/plain"}},
 		"header newline":     {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Title": "a\r\nb"}},
 		"header bad name":    {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X Title": "a"}},
+		"header empty name":  {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"": "a"}},
+		"header bracket":     {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X[Trace]": "a"}},
+		"header colon":       {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Title:": "a"}},
+		"header non-ASCII":   {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Tïtle": "a"}},
+		"header U+0019":      {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Title": "a\u0019b"}},
+		"header NUL":         {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Title": "a\x00b"}},
+		"header DEL":         {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"X-Title": "a\x7fb"}},
+		"host hdr":           {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"host": "other.example"}},
+		"content-length hdr": {BaseURL: "https://example.com/v1", StructuredOutput: JSONSchema, Headers: map[string]string{"Content-Length": "1"}},
 	}
 	for name, cfg := range cases {
 		cfg.APIKey = testKey