base-golang/pkg/downloader/protocol/http/fetcher.go

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package http
import (
"bytes"
"context"
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"crypto/tls"
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"fmt"
"gitea.bvbej.com/bvbej/base-golang/pkg/downloader/base"
"gitea.bvbej.com/bvbej/base-golang/pkg/downloader/fetcher"
"golang.org/x/sync/errgroup"
"io"
"mime"
"net"
"net/http"
"net/url"
"path"
"path/filepath"
"strconv"
"strings"
"time"
)
type RequestError struct {
Code int
Msg string
}
func NewRequestError(code int, msg string) *RequestError {
return &RequestError{Code: code, Msg: msg}
}
func (re *RequestError) Error() string {
return fmt.Sprintf("http request fail,code:%d", re.Code)
}
type Fetcher struct {
*fetcher.DefaultFetcher
res *base.Resource
opts *base.Options
status base.Status
clients []*http.Response
chunks []*Chunk
ctx context.Context
cancel context.CancelFunc
pauseCh chan any
}
func NewFetcher() *Fetcher {
return &Fetcher{
DefaultFetcher: new(fetcher.DefaultFetcher),
pauseCh: make(chan any),
}
}
var protocols = []string{"HTTP", "HTTPS"}
func FetcherBuilder() ([]string, func() fetcher.Fetcher) {
return protocols, func() fetcher.Fetcher {
return NewFetcher()
}
}
func (f *Fetcher) Resolve(req *base.Request) (*base.Resource, error) {
httpReq, err := f.buildRequest(nil, req)
if err != nil {
return nil, err
}
client, err := f.buildClient()
if err != nil {
return nil, err
}
// 只访问一个字节测试资源是否支持Range请求
httpReq.Header.Set(base.HttpHeaderRange, fmt.Sprintf(base.HttpHeaderRangeFormat, 0, 0))
httpResp, err := client.Do(httpReq)
if err != nil {
return nil, err
}
// 拿到响应头就关闭不用加defer
_ = httpResp.Body.Close()
res := &base.Resource{
Req: req,
Range: false,
Files: []*base.FileInfo{},
}
if base.HttpCodePartialContent == httpResp.StatusCode {
// 返回206响应码表示支持断点下载
res.Range = true
// 解析资源大小: bytes 0-1000/1001 => 1001
contentTotal := path.Base(httpResp.Header.Get(base.HttpHeaderContentRange))
if contentTotal != "" {
parse, err := strconv.ParseInt(contentTotal, 10, 64)
if err != nil {
return nil, err
}
res.TotalSize = parse
}
} else if base.HttpCodeOK == httpResp.StatusCode {
// 返回200响应码不支持断点下载通过Content-Length头获取文件大小获取不到的话可能是chunked编码
contentLength := httpResp.Header.Get(base.HttpHeaderContentLength)
if contentLength != "" {
parse, err := strconv.ParseInt(contentLength, 10, 64)
if err != nil {
return nil, err
}
res.TotalSize = parse
}
} else {
return nil, NewRequestError(httpResp.StatusCode, httpResp.Status)
}
file := &base.FileInfo{
Size: res.TotalSize,
}
contentDisposition := httpResp.Header.Get(base.HttpHeaderContentDisposition)
if contentDisposition != "" {
_, params, _ := mime.ParseMediaType(contentDisposition)
filename := params["filename"]
if filename != "" {
file.Name = filename
}
}
// Get file filename by URL
if file.Name == "" && strings.Count(req.URL, "/") > 2 {
file.Name = filepath.Base(req.URL)
}
// unknown file filename
if file.Name == "" {
file.Name = "unknown"
}
res.Files = append(res.Files, file)
return res, nil
}
func (f *Fetcher) Create(res *base.Resource, opts *base.Options) error {
f.res = res
f.opts = opts
f.status = base.DownloadStatusReady
return nil
}
func (f *Fetcher) Start() (err error) {
// 创建文件
name := f.filename()
_, err = f.Ctl.Touch(name, f.res.TotalSize)
if err != nil {
return err
}
f.status = base.DownloadStatusStart
if f.res.Range {
// 每个连接平均需要下载的分块大小
chunkSize := f.res.TotalSize / int64(f.opts.Connections)
f.chunks = make([]*Chunk, f.opts.Connections)
f.clients = make([]*http.Response, f.opts.Connections)
for i := 0; i < f.opts.Connections; i++ {
var (
begin = chunkSize * int64(i)
end int64
)
if i == f.opts.Connections-1 {
// 最后一个分块需要保证把文件下载完
end = f.res.TotalSize - 1
} else {
end = begin + chunkSize - 1
}
chunk := NewChunk(begin, end)
f.chunks[i] = chunk
}
} else {
// 只支持单连接下载
f.chunks = make([]*Chunk, 1)
f.clients = make([]*http.Response, 1)
f.chunks[0] = NewChunk(0, 0)
}
f.fetch()
return
}
func (f *Fetcher) Pause() (err error) {
if base.DownloadStatusStart != f.status {
return
}
f.status = base.DownloadStatusPause
f.cancel()
<-f.pauseCh
return
}
func (f *Fetcher) Continue() (err error) {
if base.DownloadStatusStart == f.status || base.DownloadStatusDone == f.status {
return
}
f.status = base.DownloadStatusStart
var name = f.filename()
_, err = f.Ctl.Open(name)
if err != nil {
return err
}
f.fetch()
return
}
func (f *Fetcher) Progress() fetcher.Progress {
p := make(fetcher.Progress, 0)
if len(f.chunks) > 0 {
total := int64(0)
for _, chunk := range f.chunks {
total += chunk.Downloaded
}
p = append(p, total)
}
return p
}
func (f *Fetcher) filename() string {
// 创建文件
var filename = f.opts.Name
if filename == "" {
filename = f.res.Files[0].Name
}
return filepath.Join(f.opts.Path, filename)
}
func (f *Fetcher) fetch() {
f.ctx, f.cancel = context.WithCancel(context.Background())
eg, _ := errgroup.WithContext(f.ctx)
for i := 0; i < f.opts.Connections; i++ {
eg.Go(func() error {
return f.fetchChunk(i)
})
}
go func() {
err := eg.Wait()
// 下载停止,关闭文件句柄
_ = f.Ctl.Close(f.filename())
if f.status == base.DownloadStatusPause {
f.pauseCh <- nil
} else {
if err != nil {
f.status = base.DownloadStatusError
} else {
f.status = base.DownloadStatusDone
}
f.DoneCh <- err
}
}()
}
func (f *Fetcher) fetchChunk(index int) (err error) {
filename := f.filename()
chunk := f.chunks[index]
httpReq, err := f.buildRequest(f.ctx, f.res.Req)
if err != nil {
return err
}
client, err := f.buildClient()
if err != nil {
return err
}
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var buf = make([]byte, 64*1024) // 64KB
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// 重试10次
for i := 0; i < 10; i++ {
// 如果下载完成直接返回
if chunk.Status == base.DownloadStatusDone {
return
}
// 如果已暂停直接跳出
if f.status == base.DownloadStatusPause {
break
}
var (
resp *http.Response
retry bool
)
if f.res.Range {
httpReq.Header.Set(base.HttpHeaderRange,
fmt.Sprintf(base.HttpHeaderRangeFormat, chunk.Begin+chunk.Downloaded, chunk.End))
} else {
chunk.Downloaded = 0
}
err = func() error {
resp, err = client.Do(httpReq)
if err != nil {
return err
}
f.clients[index] = resp
if resp.StatusCode != base.HttpCodeOK && resp.StatusCode != base.HttpCodePartialContent {
err = NewRequestError(resp.StatusCode, resp.Status)
return err
}
return nil
}()
if err != nil {
//请求失败3s后重试
time.Sleep(time.Second * 3)
continue
}
// 请求成功就重置错误次数连续失败10次才终止
i = 0
retry, err = func() (bool, error) {
defer func() {
_ = resp.Body.Close()
}()
var n int
for {
n, err = resp.Body.Read(buf)
if n > 0 {
_, err = f.Ctl.Write(filename, chunk.Begin+chunk.Downloaded, buf[:n])
if err != nil {
return false, err
}
chunk.Downloaded += int64(n)
}
if err != nil {
if err != io.EOF {
return true, err
}
break
}
}
return false, nil
}()
if !retry {
// 下载成功,跳出重试
break
}
}
if f.status == base.DownloadStatusPause {
chunk.Status = base.DownloadStatusPause
} else if chunk.Downloaded >= chunk.End-chunk.Begin+1 {
chunk.Status = base.DownloadStatusDone
} else {
if err != nil {
chunk.Status = base.DownloadStatusError
} else {
chunk.Status = base.DownloadStatusDone
}
}
return
}
func (f *Fetcher) buildClient() (*http.Client, error) {
dialer, err := f.Ctl.ContextDialer()
if err != nil {
return nil, err
}
transport := &http.Transport{
DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
return dialer.Dial(network, addr)
},
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TLSClientConfig: &tls.Config{
InsecureSkipVerify: f.Ctl.ContextInsecureSkipVerify(),
},
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}
if f.Ctl.ContextProxy() != nil {
transport.Proxy = f.Ctl.ContextProxy()
}
return &http.Client{
Jar: f.Ctl.ContextCookie(),
Timeout: f.Ctl.ContextTimeout(),
Transport: transport,
}, nil
}
func (f *Fetcher) buildRequest(ctx context.Context, req *base.Request) (httpReq *http.Request, err error) {
reqUrl, err := url.Parse(req.URL)
if err != nil {
return
}
var (
method string
body io.Reader
)
headers := make(map[string][]string)
if req.Extra == nil {
method = http.MethodGet
} else {
extra := req.Extra.(Extra)
if extra.Method != "" {
method = extra.Method
} else {
method = http.MethodGet
}
if len(extra.Header) > 0 {
for k, v := range extra.Header {
headers[k] = []string{v}
}
}
if extra.Body != "" {
body = io.NopCloser(bytes.NewBufferString(extra.Body))
}
}
if ctx != nil {
httpReq, err = http.NewRequestWithContext(ctx, method, reqUrl.String(), body)
} else {
httpReq, err = http.NewRequest(method, reqUrl.String(), body)
}
if err != nil {
return
}
httpReq.Header = headers
return httpReq, nil
}