Provide "LDConfigSetProxyURI" in the 3.x client-side C/C++ SDK

[ngangomsamananda]

Is your feature request related to a problem? Please describe. We are stuck on the end-of-life LDSDK v2.5.2 because "LDConfigSetProxyURI" is not available in the v3.x client-side C/C++ SDK.

• Our large enterprise application needs to connect to LaunchDarkly through a web proxy as some customers require it to get our software operational in their environment (for installation or login issues).
• Our application currently relies on v2.5.2 LDConfigSetProxyURI to make this connection.
• LDSDK v2.5.x reached end of life (EOL) on 2024-06-01 https://docs.launchdarkly.com/sdk/concepts/supported-versions.
• We need to upgrade to v3.x to remain on a supported version.
• We attempted an upgrade from v2.5.2 to v3.5.0 but it failed and had to be reverted due to the inability to manually configure proxy servers.
• We see that connecting to LaunchDarkly through a web proxy is called out as not yet available in version 3: https://docs.launchdarkly.com/sdk/features/web-proxy#client-side-sdks.

Describe the solution you'd like Support for LDConfigSetProxyURI in the v3.x client-side C/C++ SDK for connecting to LaunchDarkly through a web proxy.

Describe alternatives you've considered

• We upgraded to v3.5.0 but found the functionality missing.

• We confirmed in the LDSDK documentation that this feature is available in the client-side C++ SDK's version 2.x only. It is not yet available in version 3.0.

  Additional context Add any other context about the feature request here.

[cwaldren-ld]

Hi @ngangomsamananda , you filed this issue earlier: https://github.com/launchdarkly/cpp-sdks/issues/394

Was the workaround I provided not sufficient, or has the requirements changed?

[ngangomsamananda]

@cwaldren-ld the requirements have changed. Could you take up this on priority? We are stuck in the upgrade process. Thanks.

[cwaldren-ld]

Ok, what are the new requirements? Why does the previous workaround no longer work?

[ngangomsamananda]

The workaround LDClientConfigBuilder_ServiceEndpoints_RelayProxyBaseURL which you had provided supports only HTTP/HTTPS proxy. For certain use case we need a similar API of LDConfigSetProxyURI in new SDK for SOCKS proxies.

[cwaldren-ld]

Is it SOCKS4 or SOCKS5 or both? I will file a feature request, but I cannot promise any timeline.

[ngangomsamananda]

Hi @cwaldren-ld I got know to we need to support all kinds of proxy currently available in the world including HTTP/HTTPS and SOCKS. In the old version (v2.5.2) LDConfigSetProxyURI all types of proxy https://github.com/launchdarkly/c-client-sdk/blob/main/include/launchdarkly/config.h#L106 https://curl.se/ is the where the list of supported proxy is available in old version of SDK. Since we have a larger number of customers and the proxy is depending on the customer setup, we would consider any type of proxy currently available.

[ngangomsamananda]

We need the same feature of LDConfigSetProxyURI in the new SDK.