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// Package download provide download utility functions
package download
import (
"bufio"
"compress/gzip"
"crypto/tls"
"fmt"
"io"
"net/http"
"net/url"
"os"
"strconv"
"strings"
"sync"
"time"
"github.com/pkg/errors"
"github.com/tidwall/gjson"
"github.com/Mrs4s/go-cqhttp/internal/base"
)
var client = &http.Client{
Transport: &http.Transport{
Proxy: func(request *http.Request) (*url.URL, error) {
if base.Proxy == "" {
return http.ProxyFromEnvironment(request)
}
return url.Parse(base.Proxy)
},
// Disable http2
TLSNextProto: map[string]func(authority string, c *tls.Conn) http.RoundTripper{},
MaxIdleConnsPerHost: 999,
},
Timeout: time.Second * 5,
}
var clienth2 = &http.Client{
Transport: &http.Transport{
Proxy: func(request *http.Request) (*url.URL, error) {
if base.Proxy == "" {
return http.ProxyFromEnvironment(request)
}
return url.Parse(base.Proxy)
},
ForceAttemptHTTP2: true,
MaxIdleConnsPerHost: 999,
},
Timeout: time.Second * 5,
}
// ErrOverSize 响应主体过大时返回此错误
var ErrOverSize = errors.New("oversize")
// UserAgent HTTP请求时使用的UA
const UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36 Edg/87.0.664.66"
// SetTimeout set internal/download client timeout
func SetTimeout(t time.Duration) {
if t == 0 {
t = time.Second * 10
}
client.Timeout = t
clienth2.Timeout = t
}
// Request is a file download request
type Request struct {
Method string
URL string
Header map[string]string
Limit int64
Body io.Reader
}
func (r Request) client() *http.Client {
if strings.Contains(r.URL, "go-cqhttp.org") {
return clienth2
}
return client
}
func (r Request) do() (*http.Response, error) {
if r.Method == "" {
r.Method = http.MethodGet
}
req, err := http.NewRequest(r.Method, r.URL, r.Body)
if err != nil {
return nil, err
}
req.Header["User-Agent"] = []string{UserAgent}
for k, v := range r.Header {
req.Header.Set(k, v)
}
return r.client().Do(req)
}
func (r Request) body() (io.ReadCloser, error) {
resp, err := r.do()
if err != nil {
return nil, err
}
limit := r.Limit // check file size limit
if limit > 0 && resp.ContentLength > limit {
_ = resp.Body.Close()
return nil, ErrOverSize
}
if strings.Contains(resp.Header.Get("Content-Encoding"), "gzip") {
return gzipReadCloser(resp.Body)
}
return resp.Body, err
}
// Bytes 对给定URL发送请求返回响应主体
func (r Request) Bytes() ([]byte, error) {
rd, err := r.body()
if err != nil {
return nil, err
}
defer rd.Close()
return io.ReadAll(rd)
}
// JSON 发送请求, 并转换响应为JSON
func (r Request) JSON() (gjson.Result, error) {
rd, err := r.body()
if err != nil {
return gjson.Result{}, err
}
defer rd.Close()
var sb strings.Builder
_, err = io.Copy(&sb, rd)
if err != nil {
return gjson.Result{}, err
}
return gjson.Parse(sb.String()), nil
}
func writeToFile(reader io.ReadCloser, path string) error {
file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, 0o644)
if err != nil {
return err
}
defer func() { _ = file.Close() }()
_, err = file.ReadFrom(reader)
return err
}
// WriteToFile 下载到制定目录
func (r Request) WriteToFile(path string) error {
rd, err := r.body()
if err != nil {
return err
}
defer rd.Close()
return writeToFile(rd, path)
}
// WriteToFileMultiThreading 多线程下载到制定目录
func (r Request) WriteToFileMultiThreading(path string, thread int) error {
if thread < 2 {
return r.WriteToFile(path)
}
limit := r.Limit
type BlockMetaData struct {
BeginOffset int64
EndOffset int64
DownloadedSize int64
}
var blocks []*BlockMetaData
var contentLength int64
errUnsupportedMultiThreading := errors.New("unsupported multi-threading")
// 初始化分块或直接下载
initOrDownload := func() error {
header := make(map[string]string, len(r.Header))
for k, v := range r.Header { // copy headers
header[k] = v
}
header["range"] = "bytes=0-"
req := Request{
URL: r.URL,
Header: header,
}
resp, err := req.do()
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode < 200 || resp.StatusCode >= 300 {
return errors.New("response status unsuccessful: " + strconv.FormatInt(int64(resp.StatusCode), 10))
}
if resp.StatusCode == http.StatusOK {
if limit > 0 && resp.ContentLength > limit {
return ErrOverSize
}
if err = writeToFile(resp.Body, path); err != nil {
return err
}
return errUnsupportedMultiThreading
}
if resp.StatusCode == http.StatusPartialContent {
contentLength = resp.ContentLength
if limit > 0 && resp.ContentLength > limit {
return ErrOverSize
}
blockSize := contentLength
if contentLength > 1024*1024 {
blockSize = (contentLength / int64(thread)) - 10
}
if blockSize == contentLength {
return writeToFile(resp.Body, path)
}
var tmp int64
for tmp+blockSize < contentLength {
blocks = append(blocks, &BlockMetaData{
BeginOffset: tmp,
EndOffset: tmp + blockSize - 1,
})
tmp += blockSize
}
blocks = append(blocks, &BlockMetaData{
BeginOffset: tmp,
EndOffset: contentLength - 1,
})
return nil
}
return errors.New("unknown status code")
}
// 下载分块
downloadBlock := func(block *BlockMetaData) error {
file, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, 0o666)
if err != nil {
return err
}
defer file.Close()
_, _ = file.Seek(block.BeginOffset, io.SeekStart)
writer := bufio.NewWriter(file)
defer writer.Flush()
header := make(map[string]string, len(r.Header))
for k, v := range r.Header { // copy headers
header[k] = v
}
header["range"] = fmt.Sprintf("bytes=%d-%d", block.BeginOffset, block.EndOffset)
req := Request{
URL: r.URL,
Header: header,
}
resp, err := req.do()
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode < 200 || resp.StatusCode >= 300 {
return errors.New("response status unsuccessful: " + strconv.FormatInt(int64(resp.StatusCode), 10))
}
buffer := make([]byte, 1024)
i, err := resp.Body.Read(buffer)
for {
if err != nil && err != io.EOF {
return err
}
i64 := int64(len(buffer[:i]))
needSize := block.EndOffset + 1 - block.BeginOffset
if i64 > needSize {
i64 = needSize
err = io.EOF
}
_, e := writer.Write(buffer[:i64])
if e != nil {
return e
}
block.BeginOffset += i64
block.DownloadedSize += i64
if err == io.EOF || block.BeginOffset > block.EndOffset {
break
}
i, err = resp.Body.Read(buffer)
}
return nil
}
if err := initOrDownload(); err != nil {
if err == errUnsupportedMultiThreading {
return nil
}
return err
}
wg := sync.WaitGroup{}
wg.Add(len(blocks))
var lastErr error
for i := range blocks {
go func(b *BlockMetaData) {
defer wg.Done()
if err := downloadBlock(b); err != nil {
lastErr = err
}
}(blocks[i])
}
wg.Wait()
return lastErr
}
type gzipCloser struct {
f io.Closer
r *gzip.Reader
}
// gzipReadCloser 从 io.ReadCloser 创建 gunzip io.ReadCloser
func gzipReadCloser(reader io.ReadCloser) (io.ReadCloser, error) {
gzipReader, err := gzip.NewReader(reader)
if err != nil {
return nil, err
}
return &gzipCloser{
f: reader,
r: gzipReader,
}, nil
}
// Read impls io.Reader
func (g *gzipCloser) Read(p []byte) (n int, err error) {
return g.r.Read(p)
}
// Close impls io.Closer
func (g *gzipCloser) Close() error {
_ = g.f.Close()
return g.r.Close()
}