[skip changelog] Update client_example with proxy (#1162)

Author: silvanocerza

client_example/README.md

@@ -0,0 +1,32 @@
+# Client example
+
+This a client that simulates a gRPC consumer. We're using this for the time being to document the interaction with the
+gRPC interface.
+
+To use it run `arduino-cli daemon` and then `client_example`.
+
+To test the proxy settings first run:
+
+```
+docker run --name squid -d --restart=always \
+  --publish 3128:3128 \
+  --volume /path/to/squid.conf:/etc/squid/squid.conf \
+  --volume /srv/docker/squid/cache:/var/spool/squid \
+  sameersbn/squid:3.5.27-2
+```
+
+The `squid.conf` file to use is in this directory so change the volume path to that.
+
+To verify that requests are passing through the local proxy run:
+
+```
+docker exec -it squid tail -f /var/log/squid/access.log
+```
+
+If it works you should see logs similar to this:
+
+```
+1612176447.893 400234 172.17.0.1 TCP_TUNNEL/200 116430 CONNECT downloads.arduino.cc:443 - HIER_DIRECT/104.18.28.45 -
+1612176448.197 400245 172.17.0.1 TCP_TUNNEL/200 1621708 CONNECT downloads.arduino.cc:443 - HIER_DIRECT/104.18.28.45 -
+1612176448.946 400256 172.17.0.1 TCP_TUNNEL/200 354882 CONNECT downloads.arduino.cc:443 - HIER_DIRECT/104.18.28.45 -
+```

client_example/main.go

@@ -90,6 +90,10 @@ func main() {
 	log.Println("calling GetValue(foo)")
 	callGetValue(settingsClient)
 
+	// List all the settings.
+	log.Println("calling GetAll()")
+	callGetAll(settingsClient)
+
 	// Write settings to file.
 	log.Println("calling Write()")
 	callWrite(settingsClient)
@@ -100,11 +104,19 @@ func main() {
 	log.Println("calling Init")
 	instance := initInstance(client)
 
+	// We set up the proxy and then run the update to verify that the proxy settings are currently used
+	log.Println("calling setProxy")
+	callSetProxy(settingsClient)
+
 	// With a brand new instance, the first operation should always be updating
 	// the index.
 	log.Println("calling UpdateIndex")
 	callUpdateIndex(client, instance)
 
+	// And we run update again
+	log.Println("calling UpdateIndex")
+	callUpdateIndex(client, instance)
+
 	// Let's search for a platform (also known as 'core') called 'samd'.
 	log.Println("calling PlatformSearch(samd)")
 	callPlatformSearch(client, instance)
@@ -220,6 +232,31 @@ func callSetValue(client settings.SettingsClient) {
 			JsonData: `{"data": "` + dataDir + `", "downloads": "` + path.Join(dataDir, "staging") + `", "user": "` + path.Join(dataDir, "sketchbook") + `"}`,
 		})
 
+	if err != nil {
+		log.Fatalf("Error setting settings value: %s", err)
+
+	}
+}
+
+func callSetProxy(client settings.SettingsClient) {
+	_, err := client.SetValue(context.Background(),
+		&settings.Value{
+			Key:      "network.proxy",
+			JsonData: `"http://localhost:3128"`,
+		})
+
+	if err != nil {
+		log.Fatalf("Error setting settings value: %s", err)
+	}
+}
+
+func callUnsetProxy(client settings.SettingsClient) {
+	_, err := client.SetValue(context.Background(),
+		&settings.Value{
+			Key:      "network.proxy",
+			JsonData: `""`,
+		})
+
 	if err != nil {
 		log.Fatalf("Error setting settings value: %s", err)
 	}

client_example/squid.conf

@@ -0,0 +1,42 @@
+http_port 3128
+
+acl localnet src 10.0.0.0/8     # RFC1918 possible internal network
+acl localnet src 172.16.0.0/12  # RFC1918 possible internal network
+acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
+acl localnet src fc00::/7       # RFC 4193 local private network range
+acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged) machines
+
+acl SSL_ports port 443
+
+acl Safe_ports port 80          # http
+acl Safe_ports port 21          # ftp
+acl Safe_ports port 443         # https
+acl Safe_ports port 70          # gopher
+acl Safe_ports port 210         # wais
+acl Safe_ports port 280         # http-mgmt
+acl Safe_ports port 488         # gss-http
+acl Safe_ports port 591         # filemaker
+acl Safe_ports port 777         # multiling http
+acl Safe_ports port 1025-65535  # unregistered ports
+
+acl CONNECT method CONNECT
+
+http_access deny !Safe_ports
+http_access deny CONNECT !SSL_ports
+http_access allow localhost manager
+http_access deny manager
+
+#
+# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
+#
+
+http_access allow localnet
+http_access allow localhost
+http_access allow all
+
+coredump_dir /squid/var/cache/squid
+
+refresh_pattern ^ftp:           1440    20%     10080
+refresh_pattern ^gopher:        1440    0%      1440
+refresh_pattern -i (/cgi-bin/|\?) 0     0%      0
+refresh_pattern .               0       20%     4320