Unix™ Systems Programming [Electronic resources] : Communication, Concurrency, and Threads نسخه متنی

19.12 Gateways as Portals

A gateway receives requests as though it were the origin server and acts as an intermediary for other servers. This section discusses a server program, gatewayportal, which implements a gateway as shown in Figure 19.9. In this configuration, gatewayportal directs certain requests to a web server that is inside a firewall and directs the remaining requests to a server outside the firewall. The gatewayportal program has three command-line arguments: the port number that it listens on, the default server host name and the default server port number. Start by copying proxyserver.c of Section 19.9 to gatewayportal.c. The gatewayportal program parses the initial line. If the line contains an absolute URI, gatewayportal returns an HTTP error response to the client. If the absolute path of the initial line is for a resource that starts with /usp, then gatewayportal creates a tunnel to www.usp.cs.utsa.edu. The gatewayportal program directs all other requests to the default server through another tunnel.