Reorganise so we have wrapper, unwraper and hide-eid.

unwrapper and hide-eid don't work yet, of course.

pass-1/unwrapper.c

@@ -1,7 +1,85 @@
+#include "util.h"
+#include "rlocs.h"
 
+#include <unistd.h>
+#include <errno.h>
 
+#include "packet.h"
+
+#include <sys/uio.h>
+
+/*
+ * Entry point. Expects an invocation like:
+ * unwrapper <filename of rloc database> <listen_ifname> <output_ifname>
+ */ 
 int main(int argc, char** argv)
 {
+    struct session unwrap;
+    struct recv_pkt recv_pkt;
+    struct rsp_data to_send;
+    ssize_t count;
+    int result;
     
+    if ( argc < 4 ) {
+        warn( "Usage: %s <rloc database> <listen_ifname> <output_ifname>", argv[0] );
+        return 1;
+    }
+
+    rlocs_init();
+    if ( !session_setup( &unwrap, argv[1], argv[2], argv[3] ) ) {
+        warn( "Failed to set up session, exiting" );
+        return 1;
+    }
+
+    memset( &recv_pkt, 0, sizeof( struct recv_pkt ) );
+    memset( &to_send, 0, sizeof( struct rsp_data ) );
+    
+    warn( "TODO: Write BGP interventions to file" );
+
+    info( "Processing packets" );
+    while(1) {
+        // TODO: this isn't zero-copy. Not even close
+        if ( ( count = read( unwrap.listen_if, &recv_pkt, sizeof( struct recv_pkt ) ) ) < 0 ) {
+            warn( "Failed to get a packet (%s)", strerror( errno ) );
+            break;
+        }
+        
+        info( "Got a packet \\o/. %zu bytes", count );
+        
+        switch( recv_pkt.hdr.ip.version ) {
+            case 0x04  :
+                result = unwrap_ipv4_packet( unwrap.rlocs, &recv_pkt, &to_send );
+                break;
+            case 0x06 :
+                result = unwrap_ipv6_packet( unwrap.rlocs, &recv_pkt, &to_send );
+                break;
+            default:
+                warn( "Unknown IP version: %i", recv_pkt.hdr.ip.version );
+        }
+        
+        // We can't send the unwrapped one - it'll just be returned to us
+        // forever, given our bgp interventions, unless the router is clever.
+        // TODO: make fallback-to-unwrapped a configurable option?
+        if ( !result ) { 
+            warn( "Failed to unwrap received packet, dropping." );
+            continue;
+        }
+        
+        // no failure, but nothing to forward.
+        if ( to_send.count == 0 ) {
+            continue;
+        }
+
+        // docs say this should never block and should always write everything - 
+        // trust that for now.
+        if ( ( count = writev( unwrap.output_if, to_send.iovs, to_send.count ) ) < 0 ) {
+            warn( "Error writing unwrapped packet to output: %s", strerror(errno) );
+        }
+        
+    }
+    
+    info( "Finished, cleaning up" );
+    session_teardown( &unwrap );
+
     return 0;
 }