fatal error: concurrent map read and map write

[kingname]

When I use goroutine, this line panic:

tr, _ := ja3transport.NewTransportWithConfig(browser.Ja3, &config)

the error msg is:

fatal error: concurrent map read and map write

goroutine 21 [running]:
runtime.throw(0x1358b57, 0x21)
        /usr/local/Cellar/go/1.16.3/libexec/src/runtime/panic.go:1117 +0x72 fp=0xc00004ec20 sp=0xc00004ebf0 pc=0x1036c92
runtime.mapaccess2_faststr(0x12fd980, 0xc00009ac90, 0xc0000ac979, 0x2, 0xc000080e18, 0xc000060101)
        /usr/local/Cellar/go/1.16.3/libexec/src/runtime/map_faststr.go:116 +0x4a5 fp=0xc00004ec90 sp=0xc00004ec20 pc=0x1015465
github.com/CUCyber/ja3transport.stringToSpec(0xc0000ac840, 0x153, 0x100f4b8, 0x170, 0x13497c0)
        /Users/kingname/go/pkg/mod/github.com/!c!u!cyber/ja3transport@v0.0.0-20201031204932-8a22ac8ab5d7/transport.go:152 +0x4db fp=0xc00004ee08 sp=0xc00004ec90 pc=0x12c897b
github.com/CUCyber/ja3transport.NewTransportWithConfig(0xc0000ac840, 0x153, 0xc000001680, 0x0, 0x0, 0x0)
        /Users/kingname/go/pkg/mod/github.com/!c!u!cyber/ja3transport@v0.0.0-20201031204932-8a22ac8ab5d7/transport.go:85 +0x39 fp=0xc00004ee50 sp=0xc00004ee08 pc=0x12c8399

it seems that there is a concurrent write on map at line 152 at transport.go:

The key reason is the global variable extMap:

[t94j0]

Good find. Moving extMap into the specToString function will be the quickest way to fix this issue.

[reneManqueros]

Sent a PR for this: #16