Change how we are formatting headers for sendevent and sendmsg

[winsock]

Context

The switch away from http.Header.Write() is needed for some header strings that need to be sent to FreeSWITCH. For example the extra-headers header used in sendevent NOTIFY in certain code paths.

This change makes the following header possible: extra-headers: Messages-Waiting: yes\r\nMessage-Account: example@1.1.1.1\r\nVoice-Message: 1/0\r\n

Tradeoffs

• The main trade-off here may be an increase of time building the header string. However when testing this out the difference was within microseconds and within error margins.

Overview

• Add in FormatHeaderString to command.go this sorts the header keys and then generates a string containing the formatted headers.
  • This also strips leading and trailing whitespace characters from the values and converts any \r\n sequence to just \n inside the values.
• Switch the SendEvent and SendMessage commands to use this over http.Header.Write()

[winsock]

I would love to hear what any outside users of this library think about this change. I will be leaving this open for a bit, but v1.4.1-rc1 has been tagged for anyone that needs to send line breaks for sendevent/sendmsg now.

[egorsmkv]

I do not have comments on this.

I hope it won't broke my programs on future updates :)

[winsock]

@egorsmkv My goal is to never introduce API breaking changes within major versions. Minor versions can contain new features if they don't break API compatibility. Patch versions should only contain fixes or changes that produce the same output(what this change is). At this point I do not see the need for a v2 branch anytime on the horizon.

The major impact here with this MR is potentially speed, but with my testing it seems to be within a microsecond(aka in testing error) of the standard library http.Header.Write(). It otherwise should produce the exact same output outside of allowing line feeds. In the SendEvent test for example the FormatHeaderString completes around 17µs by my measurement.

[winsock]

Actual Testing Results

It seems to be within margin of error on my machine. Custom Formatter:

=== RUN TestSendEvent_BuildMessage
15.098µs
--- PASS: TestSendEvent_BuildMessage (0.00s)

http.Header.Write():

=== RUN TestSendEvent_BuildMessage
14.576µs
--- PASS: TestSendEvent_BuildMessage (0.00s)

Full Results

[egorsmkv]

Great! Thanks for the improving of the library!