More generic proxy with examples

.gitignore

@@ -0,0 +1 @@
+.env

README.md

@@ -0,0 +1,13 @@
+<p align="center">
+  <h1>Zenflows proxy</h1>
+
+  **HTTP proxy** for **services** commonly used by [interfacer-gui](https://github.com/dyne/interfacer-gui/) 
+</p>
+
+# Currently known hosts
+- [zenflows](https://fcos.interfacer.dyne.org/)
+- [location autocomplete](https://autocomplete.search.hereapi.com/v1/autocomplete)
+- [location lookup](https://lookup.search.hereapi.com/v1/lookup)
+
+# Examples
+See subdirectory `examples`

examples/README.md

@@ -0,0 +1 @@
+# One line examples with curl

examples/run-location-autocomplete.sh

@@ -0,0 +1 @@
+curl -X GET http://localhost:8080/location-autocomplete/?q=Cuneo

examples/run-location-lookup.sh

@@ -0,0 +1 @@
+curl -X GET http://localhost:8080/location-lookup/?id=here:cm:namedplace:20112331

examples/run-zenflows1.sh

@@ -0,0 +1 @@
+curl -X POST localhost:8080/zenflows/api -d "query{instanceVariables{specs{specCurrency{id}specProjectDesign{id}specProjectProduct{id}specProjectService{id}}units{unitOne{id}}}}"

examples/run-zenflows2.sh

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+curl -X POST localhost:8080/zenflows/api -d "query{instanceVariables{specs{specCurrency{id}specProjectDesign{id}specProjectProduct{id}specProjectService{id}}units{unitOne{id}}}}"

go.mod

@@ -1,3 +1,5 @@
 module github.com/dyne/zenflows-proxy
 
 go 1.18
+
+require github.com/gorilla/mux v1.8.0 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=

main.go

@@ -1,73 +1,123 @@
 package main
 
 import (
+    "strings"
     "errors"
     "fmt"
     "io"
     "net/http"
     "os"
     "time"
     "io/ioutil"
+    "net/url"
 )
 
-func httpClient() *http.Client {
-    clientTimeout := 10 * time.Second
+const clientTimeout = 10 * time.Second
+// from https://pkg.go.dev/net/http#pkg-overview
+// Clients and Transports are safe for concurrent use by multiple goroutines
+// and for efficiency should only be created once and re-used.
+// TODO: Look at https://mauricio.github.io/golang-proxies
+var client = &http.Client{
+    Timeout: clientTimeout,
+    CheckRedirect: func(req *http.Request, via []*http.Request) error {
+        return http.ErrUseLastResponse
+    },
+}
 
-    client := &http.Client{
-        Timeout: clientTimeout,
-        CheckRedirect: func(req *http.Request, via []*http.Request) error {
-            return http.ErrUseLastResponse
-        },
-    }
+// A ProxiedHost reppresent an host we will redirect to
+// the `name` is just a string identifier (this will be the first name in the request path)
+// `buildUrl` takes the input and create the url that will be used in the request of the proxy
+// TODO: implement an authentication mechanism
+type ProxiedHost struct {
+    name string
+    // authenticatd bool
+    buildUrl func(*url.URL) *url.URL
+}
 
-    return client
+// Currently know host we will proxy to
+var proxiedHosts = []ProxiedHost {
+    ProxiedHost {
+        name: "zenflows",
+        buildUrl: func(u *url.URL) *url.URL {
+            paths := strings.SplitN(strings.TrimPrefix(u.Path, "/"), "/", 2)
+            currentUrl, _ := url.Parse("https://fcos.interfacer.dyne.org/api")
+            currentUrl.Path = paths[1]
+            return currentUrl
+        },
+    },
+    ProxiedHost {
+        name: "location-autocomplete",
+        buildUrl: func(u *url.URL) *url.URL {
+            values := u.Query()
+            values.Add("apiKey", os.Getenv("HERE_API"))
+            currentUrl, _ := url.Parse("https://autocomplete.search.hereapi.com/v1/autocomplete")
+            currentUrl.RawQuery = values.Encode()
+            return currentUrl
+        },
+    },
+    ProxiedHost {
+        name: "location-lookup",
+        buildUrl: func(u *url.URL) *url.URL {
+            values := u.Query()
+            values.Add("apiKey", os.Getenv("HERE_API"))
+            currentUrl, _ := url.Parse("https://lookup.search.hereapi.com/v1/lookup")
+            currentUrl.RawQuery = values.Encode()
+            return currentUrl
+        },
+    },
 }
 
 func getRoot(w http.ResponseWriter, r *http.Request) {
-    fmt.Printf("got / request\n")
-    io.WriteString(w, "This is my website!\n")
+    io.WriteString(w, "Here I'll put the list of proxied host\n")
 }
 
-// TODO: Look at https://mauricio.github.io/golang-proxies
-func makeProxy(prefix string, proxiedHost string) func(http.ResponseWriter, *http.Request){
-    // For there is a client for each host I want to proxy
-    client := httpClient()
-
-    return func (w http.ResponseWriter, r *http.Request) {
-        url := fmt.Sprintf("%s/%s", proxiedHost, r.URL.Path[len(prefix)+1:])
+func (p *ProxiedHost) proxyRequest (w http.ResponseWriter, r *http.Request) {
+    // The request has the path /destination_name/desired_path
+    if !strings.HasPrefix(r.URL.Path, "/" + p.name + "/") {
+        fmt.Printf("wrong destination")
+        os.Exit(1)
+    }
 
-        req, err := http.NewRequest(r.Method, url, r.Body)
-        if err != nil {
-            fmt.Printf("client: could not create request: %s\n", err)
-            os.Exit(1)
-        }
-        req.Header = r.Header
-        res, err := client.Do(req)
-        if res != nil && res.Body != nil {
-            defer func() {
-                io.Copy(ioutil.Discard, res.Body)
-                res.Body.Close()
-            }()
-        }
-        if err != nil {
-            fmt.Printf("client: error making http request: %s\n", err)
-            os.Exit(1)
-        }
-        // Read all the headers
-        for name, headers := range res.Header {
-            // Iterate all headers with one name (e.g. Content-Type)
-            for _, hdr := range headers {
-                w.Header().Add(name, hdr)
-            }
+    req, err := http.NewRequest(r.Method, p.buildUrl(r.URL).String(), r.Body)
+    if err != nil {
+        msg := fmt.Sprintf("client: could not create request: %s\n", err)
+        w.WriteHeader(http.StatusServiceUnavailable)
+        w.Write([]byte(msg))
+        return
+    }
+    req.Header = r.Header
+    res, err := client.Do(req)
+    if res != nil && res.Body != nil {
+        defer func() {
+            io.Copy(ioutil.Discard, res.Body)
+            res.Body.Close()
+        }()
+    }
+    if err != nil {
+        msg := fmt.Sprintf("client: error making http request: %s\n", err)
+        w.WriteHeader(http.StatusServiceUnavailable)
+        w.Write([]byte(msg))
+        return
+    }
+    // Read all the headers
+    for name, headers := range res.Header {
+        // Iterate all headers with one name (e.g. Content-Type)
+        for _, hdr := range headers {
+            w.Header().Add(name, hdr)
         }
-        io.Copy(w, res.Body)
     }
+    io.Copy(w, res.Body)
 }
 
+func (p *ProxiedHost) addHandle() (string, func(w http.ResponseWriter, r *http.Request)) {
+    return "/" + p.name + "/", p.proxyRequest
+}
 
 func main() {
-    //http.HandleFunc("/", getRoot)
-    http.HandleFunc("/zenflows/", makeProxy("/zenflows", "https://fcos.interfacer.dyne.org"))
+    http.HandleFunc("/", getRoot)
+    for i := 0; i<len(proxiedHosts); i++{
+        http.HandleFunc(proxiedHosts[i].addHandle())
+    }
     err := http.ListenAndServe(":8080", nil)
     if errors.Is(err, http.ErrServerClosed) {
         fmt.Printf("server closed\n")