versions: move hash generator into own package

Signed-off-by: Paul Meyer <49727155+katexochen@users.noreply.github.com>

internal/versions/hash-generator/generate.go

@@ -0,0 +1,172 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/printer"
+	"go/token"
+	"io"
+	"log"
+	"net/http"
+	"os"
+
+	"golang.org/x/tools/go/ast/astutil"
+)
+
+func mustGetHash(url string) string {
+	// remove quotes around url
+	url = url[1 : len(url)-1]
+
+	// Get the data
+	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
+	if err != nil {
+		panic(err)
+	}
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		panic(err)
+	}
+	defer resp.Body.Close()
+
+	// Check server response
+	if resp.StatusCode != http.StatusOK {
+		panic("bad status: " + resp.Status)
+	}
+
+	// Generate SHA256 hash of the file
+	sha := sha256.New()
+	if _, err := io.Copy(sha, resp.Body); err != nil {
+		panic(err)
+	}
+	fileHash := sha.Sum(nil)
+
+	// Get upstream hash
+	req, err = http.NewRequestWithContext(context.Background(), http.MethodGet, url+".sha256", http.NoBody)
+	if err != nil {
+		panic(err)
+	}
+	resp, err = http.DefaultClient.Do(req)
+	if err != nil {
+		panic(err)
+	}
+	defer resp.Body.Close()
+
+	// Check server response
+	if resp.StatusCode != http.StatusOK {
+		panic("bad status: " + resp.Status)
+	}
+
+	// Compare hashes
+
+	// Take the first 64 ascii characters = 32 bytes.
+	// Some .sha256 files contain additional information afterwards.
+	upstreamHash := make([]byte, 64)
+	if _, err = resp.Body.Read(upstreamHash); err != nil {
+		panic(err)
+	}
+	if string(upstreamHash) != fmt.Sprintf("%x", fileHash) {
+		panic("hash mismatch")
+	}
+
+	return fmt.Sprintf("\"sha256:%x\"", fileHash)
+}
+
+func main() {
+	fmt.Println("Generating hashes...")
+
+	const filePath = "./versions.go"
+
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, filePath, nil, parser.ParseComments)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var componentListsCtr, componentCtr int
+
+	newFile := astutil.Apply(file, func(cursor *astutil.Cursor) bool {
+		n := cursor.Node()
+
+		//
+		// Find CompositeLit of type 'components.Components'
+		//
+		comp, ok := n.(*ast.CompositeLit)
+		if !ok {
+			return true
+		}
+		selExpr, ok := comp.Type.(*ast.SelectorExpr)
+		if !ok {
+			return true
+		}
+		if selExpr.Sel.Name != "Components" {
+			return true
+		}
+		xIdent, ok := selExpr.X.(*ast.Ident)
+		if !ok {
+			return true
+		}
+		if xIdent.Name != "components" {
+			return true
+		}
+		componentListsCtr++
+
+		//
+		// Iterate over the components
+		//
+		for _, componentElt := range comp.Elts {
+			component := componentElt.(*ast.CompositeLit)
+			componentCtr++
+
+			var url *ast.KeyValueExpr
+			var hash *ast.KeyValueExpr
+
+			for _, e := range component.Elts {
+				kv, ok := e.(*ast.KeyValueExpr)
+				if !ok {
+					continue
+				}
+				ident, ok := kv.Key.(*ast.Ident)
+				if !ok {
+					continue
+				}
+				switch ident.Name {
+				case "URL":
+					url = kv
+				case "Hash":
+					hash = kv
+				}
+			}
+
+			fmt.Println("Generating hash for", url.Value.(*ast.BasicLit).Value)
+			hash.Value.(*ast.BasicLit).Value = mustGetHash(url.Value.(*ast.BasicLit).Value)
+		}
+
+		return true
+	}, nil,
+	)
+
+	var buf bytes.Buffer
+	printConfig := printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 8}
+
+	if err = printConfig.Fprint(&buf, fset, newFile); err != nil {
+		log.Fatalf("error formatting file %s: %s", filePath, err)
+	}
+	if err := os.WriteFile(filePath, buf.Bytes(), 0o644); err != nil {
+		log.Fatalf("error writing file %s: %s", filePath, err)
+	}
+	if componentCtr == 0 {
+		log.Fatalf("no components lists found")
+	}
+
+	fmt.Printf("Successfully generated hashes for %d components in %d component lists.\n", componentCtr, componentListsCtr)
+}