perf(hooks): replace net/http with minimal HTTP/1.0 client to shrink hook binaries

pkg/hooks/httpclient.go

@@ -0,0 +1,81 @@
+package hooks
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// maxResponseBytes caps a worker response so a misbehaving peer cannot exhaust memory.
+const maxResponseBytes = 32 << 20
+
+// Minimal HTTP/1.0 client over a raw TCP socket. Linking net/http adds ~3 MB to
+// every hook binary; hooks only speak plain JSON to the local worker. HTTP/1.0
+// makes the server skip chunked encoding and close the connection, so the body
+// is simply everything after the header block.
+type httpResponse struct {
+	Status     int
+	StatusText string
+	Body       []byte
+}
+
+func httpDo(ctx context.Context, timeout time.Duration, method string, port int, path string, body []byte) (*httpResponse, error) {
+	ctx, cancel := context.WithTimeout(ctx, timeout)
+	defer cancel()
+
+	addr := net.JoinHostPort("127.0.0.1", strconv.Itoa(port))
+	var d net.Dialer
+	conn, err := d.DialContext(ctx, "tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = conn.Close() }()
+
+	if dl, ok := ctx.Deadline(); ok {
+		_ = conn.SetDeadline(dl)
+	}
+	stop := context.AfterFunc(ctx, func() { _ = conn.Close() })
+	defer stop()
+
+	var req bytes.Buffer
+	fmt.Fprintf(&req, "%s %s HTTP/1.0\r\nHost: %s\r\n", method, path, addr)
+	if body != nil {
+		fmt.Fprintf(&req, "Content-Type: application/json\r\nContent-Length: %d\r\n", len(body))
+	}
+	req.WriteString("\r\n")
+	req.Write(body)
+	if _, err := conn.Write(req.Bytes()); err != nil {
+		return nil, err
+	}
+
+	raw, err := io.ReadAll(io.LimitReader(bufio.NewReader(conn), maxResponseBytes))
+	if err != nil {
+		return nil, err
+	}
+	return parseHTTPResponse(raw)
+}
+
+func parseHTTPResponse(raw []byte) (*httpResponse, error) {
+	head, body, found := bytes.Cut(raw, []byte("\r\n\r\n"))
+	if !found {
+		return nil, errors.New("malformed http response")
+	}
+	statusLine, _, _ := strings.Cut(string(head), "\r\n")
+	_, rest, ok := strings.Cut(statusLine, " ")
+	if !ok {
+		return nil, fmt.Errorf("malformed status line %q", statusLine)
+	}
+	codeStr, _, _ := strings.Cut(rest, " ")
+	code, err := strconv.Atoi(codeStr)
+	if err != nil {
+		return nil, fmt.Errorf("malformed status line %q", statusLine)
+	}
+	return &httpResponse{Status: code, StatusText: rest, Body: body}, nil
+}