支持Range/If-Range读取静态资源片段

internal/nodes/http_request_utils.go

@@ -0,0 +1,127 @@
+package nodes
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// 分解Range
+func httpRequestParseContentRange(rangeValue string) (result [][]int, ok bool) {
+	// 参考RFC：https://tools.ietf.org/html/rfc7233
+	index := strings.Index(rangeValue, "=")
+	if index == -1 {
+		return
+	}
+	unit := rangeValue[:index]
+	if unit != "bytes" {
+		return
+	}
+
+	rangeSetString := rangeValue[index+1:]
+	if len(rangeSetString) == 0 {
+		ok = true
+		return
+	}
+
+	pieces := strings.Split(rangeSetString, ", ")
+	for _, piece := range pieces {
+		index := strings.Index(piece, "-")
+		if index == -1 {
+			return
+		}
+		first := piece[:index]
+		firstInt := -1
+
+		var err error
+		last := piece[index+1:]
+		var lastInt = -1
+
+		if len(first) > 0 {
+			firstInt, err = strconv.Atoi(first)
+			if err != nil {
+				return
+			}
+
+			if len(last) > 0 {
+				lastInt, err = strconv.Atoi(last)
+				if err != nil {
+					return
+				}
+				if lastInt < firstInt {
+					return
+				}
+			}
+		} else {
+			if len(last) == 0 {
+				return
+			}
+
+			lastInt, err = strconv.Atoi(last)
+			if err != nil {
+				return
+			}
+			lastInt = -lastInt
+		}
+
+		result = append(result, []int{firstInt, lastInt})
+	}
+
+	ok = true
+	return
+}
+
+// 读取内容Range
+func httpRequestReadRange(reader io.Reader, buf []byte, start int, end int, callback func(buf []byte, n int) error) (ok bool, err error) {
+	if start < 0 || end < 0 {
+		return
+	}
+	seeker, ok := reader.(io.Seeker)
+	if !ok {
+		return
+	}
+	_, err = seeker.Seek(int64(start), io.SeekStart)
+	if err != nil {
+		return false, nil
+	}
+
+	offset := start
+	for {
+		n, err := reader.Read(buf)
+		if n > 0 {
+			offset += n
+			if end < offset {
+				err = callback(buf, n-(offset-end-1))
+				if err != nil {
+					return false, err
+				}
+				return true, nil
+			} else {
+				err = callback(buf, n)
+				if err != nil {
+					return false, err
+				}
+			}
+		}
+
+		if err != nil {
+			if err == io.EOF {
+				return true, nil
+			}
+			return false, err
+		}
+	}
+}
+
+// 生成boundary
+// 仿照Golang自带的函数（multipart包）
+func httpRequestGenBoundary() string {
+	var buf [30]byte
+	_, err := io.ReadFull(rand.Reader, buf[:])
+	if err != nil {
+		panic(err)
+	}
+	return fmt.Sprintf("%x", buf[:])
+}