Add config setting which preserves host header

config.sample

@@ -159,3 +159,8 @@
 # outgoing requests.
 
 # alwaysAddNoTransform = true
+
+# Uncomment this if you want to preserve the host header from the
+# incoming host HTTP request.
+
+# useClientHostHeader = true

http_parse.c

@@ -1249,7 +1249,8 @@ httpParseHeaders(int client, AtomPtr url,
                 cache_control.flags |= CACHE_COOKIE;
 
             if(hbuf) {
-                if(name != atomConnection && name != atomHost &&
+                if(name != atomConnection &&
+                   (useClientHostHeader || name != atomHost) &&
                    name != atomAcceptRange && name != atomTE &&
                    name != atomProxyAuthenticate &&
                    name != atomKeepAlive &&

server.c

@@ -40,6 +40,7 @@ int maxSideBuffering = 1500;
 int maxConnectionAge = 1260;
 int maxConnectionRequests = 400;
 int alwaysAddNoTransform = 0;
+int useClientHostHeader = 0;
 
 static HTTPServerPtr servers = 0;
 
@@ -95,6 +96,8 @@ preinitServer(void)
                              "Maximum number of requests on a server-side connection.");
     CONFIG_VARIABLE(alwaysAddNoTransform, CONFIG_BOOLEAN,
                     "If true, add a no-transform directive to all requests.");
+    CONFIG_VARIABLE_SETTABLE(useClientHostHeader, CONFIG_BOOLEAN, configIntSetter,
+                             "Use client host header.");
 }
 
 static int
@@ -1622,10 +1625,12 @@ httpWriteRequest(HTTPConnectionPtr connection, HTTPRequestPtr request,
 
     n = snnprintf(connection->reqbuf, n, bufsize, " HTTP/1.1");
 
-    n = snnprintf(connection->reqbuf, n, bufsize, "\r\nHost: ");
-    n = snnprint_n(connection->reqbuf, n, bufsize, url + x, y - x);
-    if(port != 80)
-        n = snnprintf(connection->reqbuf, n, bufsize, ":%d", port);
+    if(!useClientHostHeader) {
+		n = snnprintf(connection->reqbuf, n, bufsize, "\r\nHost: ");
+		n = snnprint_n(connection->reqbuf, n, bufsize, url + x, y - x);
+		if(port != 80)
+			n = snnprintf(connection->reqbuf, n, bufsize, ":%d", port);
+    }
 
     if(connection->server->isProxy && parentAuthCredentials) {
         n = buildServerAuthHeaders(connection->reqbuf, n, bufsize,

server.h

@@ -21,6 +21,7 @@ THE SOFTWARE.
 */
 
 extern int serverExpireTime, dontCacheRedirects;
+extern int useClientHostHeader;
 
 typedef struct _HTTPServer {
     char *name;