internal/module/module.go
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package module
import (
"context"
"encoding/json"
"fmt"
"io"
"net/http"
"os"
"path"
"strings"
"golang.org/x/mod/module"
"golang.org/x/sync/errgroup"
)
type latestResp struct {
Version string `json:"Version"`
}
type resolvedModule struct {
Module string
Version string
GoMod []byte
}
func proxyRequest(importPath, suffix string) (*http.Request, error) {
proxyBase := "https://proxy.golang.org"
if gp := os.Getenv("GOPROXY"); gp != "" {
if strings.ContainsRune(gp, ',') ||
strings.ContainsRune(gp, '|') ||
gp == "off" ||
gp == "direct" {
return nil, fmt.Errorf("only GOPROXY=<url> is supported by gore, not %q", gp)
}
proxyBase = strings.TrimSuffix(gp, "/")
}
escapedSuffix, err := module.EscapeVersion(suffix)
if err != nil {
return nil, err
}
if escapedSuffix != "@latest" {
escapedSuffix = "@v/" + escapedSuffix
}
escapedImportPath, err := module.EscapePath(importPath)
if err != nil {
return nil, err
}
req, err := http.NewRequest("GET", proxyBase+"/"+escapedImportPath+"/"+escapedSuffix, nil)
if err != nil {
return nil, err
}
// TODO: dynamic version here pls
req.Header.Set("User-Agent", "gore runs everything alpha")
return req, nil
}
func moduleInfo(ctx context.Context, importPath, version string) (*latestResp, error) {
suffix := version + ".info"
if version == "latest" {
suffix = "@latest"
}
req, err := proxyRequest(importPath, suffix)
if err != nil {
return nil, err
}
req.Header.Set("Accept", "application/json")
resp, err := http.DefaultClient.Do(req.WithContext(ctx))
if err != nil {
return nil, err
}
defer func() {
io.ReadAll(resp.Body)
resp.Body.Close()
}()
if resp.StatusCode == http.StatusNotFound {
return nil, nil
}
if got, want := resp.StatusCode, http.StatusOK; got != want {
return nil, fmt.Errorf("unexpected HTTP status: got %v, want %v", resp.Status, want)
}
var latest latestResp
b, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("reading HTTP response: %v", err)
}
if err := json.Unmarshal(b, &latest); err != nil {
return nil, fmt.Errorf("decoding /@latest response: %v", err)
}
return &latest, nil
}
func resolveGoMod(ctx context.Context, importPath string, latest *latestResp) (*resolvedModule, error) {
req, err := proxyRequest(importPath, latest.Version+".mod")
if err != nil {
return nil, err
}
resp, err := http.DefaultClient.Do(req.WithContext(ctx))
if err != nil {
return nil, err
}
defer func() {
io.ReadAll(resp.Body)
resp.Body.Close()
}()
if got, want := resp.StatusCode, http.StatusOK; got != want {
return nil, fmt.Errorf("unexpected HTTP status: got %v, want %v", resp.Status, want)
}
b, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("reading HTTP response: %v", err)
}
return &resolvedModule{
module: importPath,
version: latest.Version,
goMod: b,
}, nil
}
func Resolve(ctx context.Context, importPath, version string) (*resolvedModule, error) {
eg, latestctx := errgroup.WithContext(ctx)
parts := strings.Split(path.Clean(importPath), "/")
resps := make([]*latestResp, len(parts))
for idx := len(parts); idx > 0; idx-- {
idx := idx // copy
importPath := strings.Join(parts[:idx], "/")
eg.Go(func() error {
if importPath == "github.com" {
// Short-circuit: github.com is not a Go module :)
return nil
}
if strings.HasPrefix(importPath, "github.com/") &&
!strings.ContainsRune(strings.TrimPrefix(importPath, "github.com/"), '/') {
// Short-circuit: github.com/<something> references an
// organisation or user, not a repository.
return nil
}
resp, err := moduleInfo(latestctx, importPath, version)
if err != nil {
return err
}
resps[idx-1] = resp
return nil
})
}
if err := eg.Wait(); err != nil {
return nil, err
}
for idx := len(parts); idx > 0; idx-- {
importPath := strings.Join(parts[:idx], "/")
resp := resps[idx-1]
if resp == nil {
continue
}
return resolveGoMod(ctx, importPath, resp)
}
return nil, fmt.Errorf("could not resolve import path %q to any Go module", importPath)
}