proxy: show getenv proxy use in verbose output

... to aid debugging etc as it sometimes isn't immediately obvious why
curl uses or doesn't use a proxy.

Inspired by #2477

Closes #2480

1 files changed, 19 insertions, 7 deletions

diff --git a/lib/url.c b/lib/url.c
index feb1fa70f..8c9c69141 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -2662,13 +2662,19 @@ static char *detect_proxy(struct connectdata *conn)
     prox = curl_getenv(proxy_env);
   }
 
-  if(prox)
+  envp = proxy_env;
+  if(prox) {
     proxy = prox; /* use this */
+  }
   else {
-    proxy = curl_getenv("all_proxy"); /* default proxy to use */
-    if(!proxy)
-      proxy = curl_getenv("ALL_PROXY");
+    envp = (char *)"all_proxy";
+    proxy = curl_getenv(envp); /* default proxy to use */
+    if(!proxy) {
+      envp = (char *)"ALL_PROXY";
+      proxy = curl_getenv(envp);
+    }
   }
+  infof(conn->data, "Uses proxy env variable %s == '%s'\n", envp, proxy);
 
   return proxy;
 }
@@ -2953,9 +2959,15 @@ static CURLcode create_conn_helper_init_proxy(struct connectdata *conn)
   }
 
   if(!data->set.str[STRING_NOPROXY]) {
-    no_proxy = curl_getenv("no_proxy");
-    if(!no_proxy)
-      no_proxy = curl_getenv("NO_PROXY");
+    const char *p = "no_proxy";
+    no_proxy = curl_getenv(p);
+    if(!no_proxy) {
+      p = "NO_PROXY";
+      no_proxy = curl_getenv(p);
+    }
+    if(no_proxy) {
+      infof(conn->data, "Uses proxy env variable %s == '%s'\n", p, no_proxy);
+    }
   }
 
   if(check_noproxy(conn->host.name, data->set.str[STRING_NOPROXY] ?