60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
// Package useragent provides helper functions to pack
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// version information into a single User-Agent header.
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package useragent
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import (
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"errors"
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"strings"
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)
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var (
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ErrNilRequest = errors.New("request cannot be nil")
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)
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// VersionInfo is used to model UserAgent versions.
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type VersionInfo struct {
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Name string
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Version string
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}
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func (vi *VersionInfo) isValid() bool {
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const stopChars = " \t\r\n/"
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name := vi.Name
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vers := vi.Version
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if len(name) == 0 || strings.ContainsAny(name, stopChars) {
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return false
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}
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if len(vers) == 0 || strings.ContainsAny(vers, stopChars) {
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return false
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}
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return true
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}
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// Convert versions to a string and append the string to the string base.
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//
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// Each VersionInfo will be converted to a string in the format of
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// "product/version", where the "product" is get from the name field, while
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// version is get from the version field. Several pieces of verson information
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// will be concatinated and separated by space.
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//
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// Example:
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// AppendVersions("base", VersionInfo{"foo", "1.0"}, VersionInfo{"bar", "2.0"})
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// results in "base foo/1.0 bar/2.0".
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func AppendVersions(base string, versions ...VersionInfo) string {
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if len(versions) == 0 {
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return base
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}
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verstrs := make([]string, 0, 1+len(versions))
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if len(base) > 0 {
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verstrs = append(verstrs, base)
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}
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for _, v := range versions {
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if !v.isValid() {
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continue
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}
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verstrs = append(verstrs, v.Name+"/"+v.Version)
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}
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return strings.Join(verstrs, " ")
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}
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