96 lines
3.1 KiB
Markdown
96 lines
3.1 KiB
Markdown
# noctx
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`noctx` finds sending http request without context.Context.
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You should use `noctx` if sending http request in your library.
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Passing `context.Context` enables library user to cancel http request, getting trace information and so on.
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## Install
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```sh
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$ go get -u github.com/sonatard/noctx/cmd/noctx
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```
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## Usage
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```sh
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$ go vet -vettool=`which noctx` main.go
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./main.go:6:11: net/http.Get must not be called
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```
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## Detection rules
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- Executing following functions
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- `net/http.Get`
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- `net/http.Head`
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- `net/http.Post`
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- `net/http.PostForm`
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- `(*net/http.Client).Get`
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- `(*net/http.Client).Head`
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- `(*net/http.Client).Post`
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- `(*net/http.Client).PostForm`
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- `http.Request` returned by `http.NewRequest` function and passes it to other function.
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## How to fix
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- Send http request using `(*http.Client).Do(*http.Request)` method.
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- In Go 1.13 and later, use `http.NewRequestWithContext` function instead of using `http.NewRequest` function.
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- In Go 1.12 and earlier, call `(http.Request).WithContext(ctx)` after `http.NewRequest`.
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`(http.Request).WithContext(ctx)` has a disadvantage of performance because it returns a copy of `http.Request`. Use `http.NewRequestWithContext` function if you only support Go1.13 or later.
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## Sample Code
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```go
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package main
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import (
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"context"
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"net/http"
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)
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func main() {
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const url = "http://example.com"
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http.Get(url) // want `net/http\.Get must not be called`
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http.Head(url) // want `net/http\.Head must not be called`
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http.Post(url, "", nil) // want `net/http\.Post must not be called`
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http.PostForm(url, nil) // want `net/http\.PostForm must not be called`
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cli := &http.Client{}
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cli.Get(url) // want `\(\*net/http\.Client\)\.Get must not be called`
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cli.Head(url) // want `\(\*net/http\.Client\)\.Head must not be called`
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cli.Post(url, "", nil) // want `\(\*net/http\.Client\)\.Post must not be called`
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cli.PostForm(url, nil) // want `\(\*net/http\.Client\)\.PostForm must not be called`
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req, _ := http.NewRequest(http.MethodPost, url, nil) // want `should rewrite http.NewRequestWithContext or add \(\*Request\).WithContext`
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cli.Do(req)
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ctx := context.Background()
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req2, _ := http.NewRequestWithContext(ctx, http.MethodPost, url, nil) // OK
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cli.Do(req2)
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req3, _ := http.NewRequest(http.MethodPost, url, nil) // OK
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req3 = req3.WithContext(ctx)
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cli.Do(req3)
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f2 := func(req *http.Request, ctx context.Context) *http.Request {
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return req
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}
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req4, _ := http.NewRequest(http.MethodPost, url, nil) // want `should rewrite http.NewRequestWithContext or add \(\*Request\).WithContext`
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req4 = f2(req4, ctx)
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cli.Do(req4)
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req5, _ := func() (*http.Request, error) {
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return http.NewRequest(http.MethodPost, url, nil) // want `should rewrite http.NewRequestWithContext or add \(\*Request\).WithContext`
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}()
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cli.Do(req5)
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}
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```
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## Reference
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- [net/http - NewRequest](https://golang.org/pkg/net/http/#NewRequest)
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- [net/http - NewRequestWithContext](https://golang.org/pkg/net/http/#NewRequestWithContext)
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- [net/http - Request.WithContext](https://golang.org/pkg/net/http/#Request.WithContext)
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