Is there a method to generate a UUID with go language

Question

I have code that looks like this   u    make   byte  16     err    rand Read u  if err    nil       return    u 8     u 8    0x80   amp  0xBF    what does this do  u 6     u 6    0x40   amp  0x4F    what does this do   return hex EncodeToString u    It returns a string with a length of 32  but I don t think it is a valid UUID  If it is a real UUID  why is it a UUID  and what is the purpose of the code that modifies the value of u 8  and u 6    Is there a better way of generating UUIDs

User · Answer

The go-uuid library is NOT RFC4122 compliant  The variant bits are not set correctly  There have been several attempts by community members to have this fixed but pull requests for the fix are not being accepted   You can generate UUIDs using the Go uuid library I rewrote based on the go-uuid library  There are several fixes and improvements  This can be installed with   go get github com twinj uuid   You can generate random  version 4  UUIDs with   import  github com twinj uuid   u    uuid NewV4     The returned UUID type is an interface and the underlying type is an array   The library also generates v1 UUIDs and correctly generates v3 and 5 UUIDs  There are several new methods to help with printing and formatting and also new general methods to create UUIDs based off of existing data

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As part of the uuid spec  if you generate a uuid from random it must contain a  4  as the 13th character and a  8    9    a   or  b  in the 17th  source       this makes sure that the 13th character is  4  u 6     u 6    0x40   amp  0x4F    this makes sure that the 17th is  8    9    a   or  b  u 8     u 8    0x80   amp  0xBF

User · Answer

On Linux  you can read from  proc sys kernel random uuid   package main  import  io ioutil  import  fmt   func main         u       ioutil ReadFile   proc sys kernel random uuid       fmt Println string u       No external dependencies     go run uuid go  3ee995e3-0c96-4e30-ac1e-f7f04fd03e44

User · Answer

crypto rand  is cross platform pkg for random bytes generattion  package main  import        crypto rand       fmt        Note - NOT RFC4122 compliant func pseudo uuid    uuid string         b    make   byte  16         err    rand Read b      if err    nil           fmt Println  Error     err          return            uuid   fmt Sprintf   X- X- X- X- X   b 0 4   b 4 6   b 6 8   b 8 10   b 10         return

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For Windows  I did recently this       build windows  package main  import        syscall       unsafe     var       modrpcrt4   syscall NewLazyDLL  rpcrt4 dll       procUuidCreate   modrpcrt4 NewProc  UuidCreate      const       RPC S OK   0    func NewUuid      byte  error        var uuid  16 byte     rc     e    syscall Syscall procUuidCreate Addr    1               uintptr unsafe Pointer  amp uuid 0     0  0      if int rc     RPC S OK           if e    0               return nil  error e            else               return nil  syscall EINVAL                     return uuid     nil

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The gorand package has a UUID method that returns a Version 4  randomly generated  UUID in its canonical string representation   xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx   and it s RFC 4122 compliant   It also uses the crypto rand package to ensure the most cryptographically secure generation of UUIDs across all platforms supported by Go   import  github com leonelquinteros gorand   func main         uuid  err    gorand UUID       if err    nil           panic err Error               println uuid

User · Answer

u 8     u 8    0x80   amp  0xBF    what s the purpose   u 6     u 6    0x40   amp  0x4F    what s the purpose     These lines clamp the values of byte 6 and 8 to a specific range  rand Read returns random bytes in the range 0-255  which are not all valid values for a UUID  As far as I can tell  this should be done for all the values in the slice though   If you are on linux  you can alternatively call  usr bin uuidgen   package main  import        fmt       log       os exec     func main         out  err    exec Command  uuidgen   Output       if err    nil           log Fatal err            fmt Printf   s   out      Which yields     go run uuid go  dc9076e9-2fda-4019-bd2c-900a8284b9c4

User · Answer

You can generate UUIDs using the go-uuid library   This can be installed with   go get github com nu7hatch gouuid   You can generate random  version 4  UUIDs with   import  github com nu7hatch gouuid        u  err    uuid NewV4     The returned UUID type is a 16 byte array  so you can retrieve the binary value easily   It also provides the standard hex string representation via its String   method   The code you have also looks like it will also generate a valid version 4 UUID  the bitwise manipulation you perform at the end set the version and variant fields of the UUID to correctly identify it as version 4   This is done to distinguish random UUIDs from ones generated via other algorithms  e g  version 1 UUIDs based on your MAC address and time

User · Answer

From Russ Cox s post      There s no official library   Ignoring error checking    this seems like it would work fine    f       os Open   dev urandom   b    make   byte  16  f Read b  f Close   uuid    fmt Sprintf   x- x- x- x- x   b 0 4   b 4 6   b 6 8   b 8 10   b 10      Note  In the original  pre Go 1 version the first line was   f       os Open   dev urandom   os O RDONLY  0    Here it compiles and executes  only  dev urandom returns all zeros in the playground  Should work fine locally   In the same thread there are some other methods references packages found

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There is an official implementation by Google  https   github com google uuid  Generating a version 4 UUID works like this   package main  import        fmt       github com google uuid     func main         id    uuid New       fmt Println id String        Try it here  https   play golang org p 6YPi1djUMj9

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This library is our standard for uuid generation and parsing    https   github com pborman uuid

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gofrs uuid is the replacement for satori go uuid  which is the most starred UUID package for Go  It supports UUID versions 1-5 and is RFC 4122 and DCE 1 1 compliant   import  github com gofrs uuid      Create a Version 4 UUID  panicking on error u    uuid Must uuid NewV4

[go] Is there a method to generate a UUID with go language

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