feat: add custom version HTTP header string to RPC requests

Author: steveluscher

rollup.config.js

@@ -71,6 +71,9 @@ function generateConfig(configType, format) {
         values: {
           'process.env.NODE_ENV': JSON.stringify(env),
           'process.env.BROWSER': JSON.stringify(browser),
+          'process.env.npm_package_version': JSON.stringify(
+            process.env.npm_package_version,
+          ),
         },
       }),
     ],

src/connection.ts

@@ -995,6 +995,7 @@ function createRpcClient(
           'Content-Type': 'application/json',
         },
         httpHeaders || {},
+        COMMON_HTTP_HEADERS,
       ),
     };
 
@@ -2158,7 +2159,12 @@ export type ConfirmedSignatureInfo = {
 /**
  * An object defining headers to be passed to the RPC server
  */
-export type HttpHeaders = {[header: string]: string};
+export type HttpHeaders = {
+  [header: string]: string;
+} & {
+  // Prohibited headers; for internal use only.
+  'solana-client'?: never;
+};
 
 /**
  * The type of the JavaScript `fetch()` API
@@ -2194,6 +2200,11 @@ export type ConnectionConfig = {
   confirmTransactionInitialTimeout?: number;
 };
 
+/** @internal */
+const COMMON_HTTP_HEADERS = {
+  'solana-client': `js/${process.env.npm_package_version ?? 'UNKNOWN'}`,
+};
+
 /**
  * A connection to a fullnode JSON RPC endpoint
  */