Add --vpn (-X) flag to support sending IP pkts

When a user specifies a `-i tun0` flag for a VPN interface,
this interface expects raw IP packets, not ethernet frames.
The --vpn option allows you to send only IP packets to the
specified interface, and also performs some hacks on the receive
end to ensure we can process the results.

TODO: malloc a fake ethernet header for probe_modules.process_packet
(or better yet, make process_packet always take an IP packet, they
all seem to be implicitly doing that anyway).

src/recv.c

@@ -74,12 +74,12 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
 	// length of entire packet captured by libpcap
 	uint32_t buflen = (uint32_t) p->caplen;
 
-	if ((sizeof(struct iphdr) + sizeof(struct ethhdr)) > buflen) {
+	if ((sizeof(struct iphdr) + (zconf.send_ip_pkts ? 0 : sizeof(struct ethhdr))) > buflen) {
 		// buffer not large enough to contain ethernet
 		// and ip headers. further action would overrun buf
 		return;
 	}
-	struct iphdr *ip_hdr = (struct iphdr *)&bytes[sizeof(struct ethhdr)];
+	struct iphdr *ip_hdr = (struct iphdr *)&bytes[(zconf.send_ip_pkts ? 0 : sizeof(struct ethhdr))];
 
 	uint32_t src_ip = ip_hdr->saddr;
 
@@ -88,7 +88,7 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
 	// and we must calculate off potential payload message instead
 	validate_gen(ip_hdr->daddr, ip_hdr->saddr, (uint8_t *)validation);
 
-	if (!zconf.probe_module->validate_packet(ip_hdr, buflen - sizeof(struct ethhdr),
+	if (!zconf.probe_module->validate_packet(ip_hdr, buflen - (zconf.send_ip_pkts ? 0 : sizeof(struct ethhdr)),
 				&src_ip, validation)) {
 		return;
 	}
@@ -97,7 +97,18 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
 
 	fieldset_t *fs = fs_new_fieldset();
 	fs_add_ip_fields(fs, ip_hdr);
-	zconf.probe_module->process_packet(bytes, buflen, fs);
+    // HACK !!! FIXME !!! TODO !!! BAD BAD BAD
+    // probe modules for whatever reason expect the full ethernet frame
+    // in process_packet. For VPN, we only get back an IP frame
+    // so we COULD malloc a fake ethernet frame and copy over this payload
+    // but waaaaaaahhhh performanceeee.
+    // so instead, we will ASSUME (!) that the probe module will only care about
+    // the IP header, and do ip_hdr = &packet[sizeof(struct ethhdr)] the first thing
+    // in their function (tcp, icmp and udp probe modules all do).
+    //
+    // !!!IF YOUR PROBE MODULE USES THE ETH PACKET, AND YOU USE THE --vpn OPTION, YOU _WILL_ BE OWNED!!!!
+    //
+	zconf.probe_module->process_packet(bytes - (zconf.send_ip_pkts * sizeof(struct ethhdr)), buflen + (zconf.send_ip_pkts * sizeof(struct ethhdr)), fs);
 	fs_add_system_fields(fs, is_repeat, zsend.complete);
 	int success_index = zconf.fsconf.success_index;
 	assert(success_index < fs->len);
@@ -115,7 +126,6 @@ void packet_cb(u_char __attribute__((__unused__)) *user,
 				zrecv.cooldown_unique++;
 			}
 		}
-		
 	} else {
 		zrecv.failure_total++;
 	}

src/send.c

@@ -288,7 +288,7 @@ int send_run(int sock)
 				zconf.probe_module->print_packet(stdout, buf);
 			} else {
 					int l = zconf.probe_module->packet_length;
-					int rc = sendto(sock, buf, 
+					int rc = sendto(sock, buf + zconf.send_ip_pkts*sizeof(struct ethhdr),
 							l, 0,
 							(struct sockaddr *)&sockaddr,
 							sizeof(struct sockaddr_ll));

src/state.c

@@ -14,7 +14,7 @@
 struct state_conf zconf = {
 	.log_level = LOG_INFO,
 	.source_port_first = 32768, // (these are the default
-	.source_port_last = 61000,  //   ephemeral range on Linux)
+	.source_port_last = 61000,	//	 ephemeral range on Linux)
 	.output_filename = NULL,
 	.blacklist_filename = NULL,
 	.whitelist_filename = NULL,
@@ -36,6 +36,7 @@ struct state_conf zconf = {
 	.probe_args = NULL,
 	.gw_mac = {0},
 	.gw_mac_set = 0,
+	.send_ip_pkts = 0,
 	.source_ip_first = NULL,
 	.source_ip_last = NULL,
 	.raw_output_fields = NULL,

src/state.h

@@ -70,7 +70,8 @@ struct state_conf {
 	char *probe_args;
 	char *output_args;
 	macaddr_t gw_mac[IFHWADDRLEN];
-  	int gw_mac_set;
+	int gw_mac_set;
+	int send_ip_pkts;
 	char *source_ip_first;
 	char *source_ip_last;
 	char *output_filename;

src/zmap.c

@@ -397,6 +397,11 @@ int main(int argc, char *argv[])
 			exit(EXIT_FAILURE);
 		}
 	}
+	if (args.vpn_given) {
+		zconf.send_ip_pkts = 1;
+		zconf.gw_mac_set = 1;
+		memset(zconf.gw_mac, 0, IFHWADDRLEN);
+	}
 	if (cmdline_parser_required(&args, CMDLINE_PARSER_PACKAGE) != 0) {
 		exit(EXIT_FAILURE);
 	}

src/zopt.c

@@ -54,6 +54,7 @@ const char *gengetopt_args_info_help[] = {
   "  -S, --source-ip=ip|range      Source address(es) for scan packets",
   "  -G, --gateway-mac=addr        Specify gateway MAC address",
   "  -i, --interface=name          Specify network interface to use",
+  "  -X, --vpn                     Sends IP packets instead of Ethernet (for VPNs)",
   "\nAdvanced options:",
   "  -M, --probe-module=name       Select probe module  (default=`tcp_synscan')",
   "  -O, --output-module=name      Select output module  (default=`csv')",
@@ -137,6 +138,7 @@ void clear_given (struct gengetopt_args_info *args_info)
   args_info->source_ip_given = 0 ;
   args_info->gateway_mac_given = 0 ;
   args_info->interface_given = 0 ;
+  args_info->vpn_given = 0 ;
   args_info->probe_module_given = 0 ;
   args_info->output_module_given = 0 ;
   args_info->probe_args_given = 0 ;
@@ -226,19 +228,20 @@ void init_args_info(struct gengetopt_args_info *args_info)
   args_info->source_ip_help = gengetopt_args_info_help[19] ;
   args_info->gateway_mac_help = gengetopt_args_info_help[20] ;
   args_info->interface_help = gengetopt_args_info_help[21] ;
-  args_info->probe_module_help = gengetopt_args_info_help[23] ;
+  args_info->vpn_help = gengetopt_args_info_help[22] ;
-  args_info->output_module_help = gengetopt_args_info_help[24] ;
+  args_info->probe_module_help = gengetopt_args_info_help[24] ;
-  args_info->probe_args_help = gengetopt_args_info_help[25] ;
+  args_info->output_module_help = gengetopt_args_info_help[25] ;
-  args_info->output_args_help = gengetopt_args_info_help[26] ;
+  args_info->probe_args_help = gengetopt_args_info_help[26] ;
-  args_info->list_output_modules_help = gengetopt_args_info_help[27] ;
+  args_info->output_args_help = gengetopt_args_info_help[27] ;
-  args_info->list_probe_modules_help = gengetopt_args_info_help[28] ;
+  args_info->list_output_modules_help = gengetopt_args_info_help[28] ;
-  args_info->list_output_fields_help = gengetopt_args_info_help[29] ;
+  args_info->list_probe_modules_help = gengetopt_args_info_help[29] ;
-  args_info->config_help = gengetopt_args_info_help[31] ;
+  args_info->list_output_fields_help = gengetopt_args_info_help[30] ;
-  args_info->quiet_help = gengetopt_args_info_help[32] ;
+  args_info->config_help = gengetopt_args_info_help[32] ;
-  args_info->summary_help = gengetopt_args_info_help[33] ;
+  args_info->quiet_help = gengetopt_args_info_help[33] ;
-  args_info->verbosity_help = gengetopt_args_info_help[34] ;
+  args_info->summary_help = gengetopt_args_info_help[34] ;
-  args_info->help_help = gengetopt_args_info_help[35] ;
+  args_info->verbosity_help = gengetopt_args_info_help[35] ;
-  args_info->version_help = gengetopt_args_info_help[36] ;
+  args_info->help_help = gengetopt_args_info_help[36] ;
+  args_info->version_help = gengetopt_args_info_help[37] ;
   
 }
 
@@ -426,6 +429,8 @@ cmdline_parser_dump(FILE *outfile, struct gengetopt_args_info *args_info)
     write_into_file(outfile, "gateway-mac", args_info->gateway_mac_orig, 0);
   if (args_info->interface_given)
     write_into_file(outfile, "interface", args_info->interface_orig, 0);
+  if (args_info->vpn_given)
+    write_into_file(outfile, "vpn", 0, 0 );
   if (args_info->probe_module_given)
     write_into_file(outfile, "probe-module", args_info->probe_module_orig, 0);
   if (args_info->output_module_given)
@@ -721,6 +726,7 @@ cmdline_parser_internal (
         { "source-ip",	1, NULL, 'S' },
         { "gateway-mac",	1, NULL, 'G' },
         { "interface",	1, NULL, 'i' },
+        { "vpn",	0, NULL, 'X' },
         { "probe-module",	1, NULL, 'M' },
         { "output-module",	1, NULL, 'O' },
         { "probe-args",	1, NULL, 0 },
@@ -737,7 +743,7 @@ cmdline_parser_internal (
         { 0,  0, 0, 0 }
       };
 
-      c = getopt_long (argc, argv, "p:o:b:w:f:n:N:t:r:B:c:e:T:P:ds:S:G:i:M:O:C:qgv:hV", long_options, &option_index);
+      c = getopt_long (argc, argv, "p:o:b:w:f:n:N:t:r:B:c:e:T:P:ds:S:G:i:XM:O:C:qgv:hV", long_options, &option_index);
 
       if (c == -1) break;	/* Exit from `while (1)' loop.  */
 
@@ -970,6 +976,18 @@ cmdline_parser_internal (
               additional_error))
             goto failure;
         
+          break;
+        case 'X':	/* Sends IP packets instead of Ethernet (for VPNs).  */
+        
+        
+          if (update_arg( 0 , 
+               0 , &(args_info->vpn_given),
+              &(local_args_info.vpn_given), optarg, 0, 0, ARG_NO,
+              check_ambiguity, override, 0, 0,
+              "vpn", 'X',
+              additional_error))
+            goto failure;
+        
           break;
         case 'M':	/* Select probe module.  */
         
@@ -988,7 +1006,7 @@ cmdline_parser_internal (
         
           if (update_arg( (void *)&(args_info->output_module_arg), 
                &(args_info->output_module_orig), &(args_info->output_module_given),
-              &(local_args_info.output_module_given), optarg, 0, "simple_file", ARG_STRING,
+              &(local_args_info.output_module_given), optarg, 0, "csv", ARG_STRING,
               check_ambiguity, override, 0, 0,
               "output-module", 'O',
               additional_error))

src/zopt.ggo

@@ -75,6 +75,8 @@ option "gateway-mac"		G "Specify gateway MAC address"
 option "interface"		i "Specify network interface to use"
 	   typestr="name"
 	   optional string
+option "vpn"		X "Sends IP packets instead of Ethernet (for VPNs)"
+	   optional
 
 section "Advanced options"
 
@@ -84,7 +86,7 @@ option "probe-module"		M "Select probe module"
 	   optional string
 option "output-module"		O "Select output module"
 	   typestr="name"
-	   default="simple_file"
+	   default="csv"
 	   optional string
 option "probe-args"		- "Arguments to pass to probe module"
 	   typestr="args"

src/zopt.h

@@ -92,10 +92,11 @@ struct gengetopt_args_info
   char * interface_arg;	/**< @brief Specify network interface to use.  */
   char * interface_orig;	/**< @brief Specify network interface to use original value given at command line.  */
   const char *interface_help; /**< @brief Specify network interface to use help description.  */
+  const char *vpn_help; /**< @brief Sends IP packets instead of Ethernet (for VPNs) help description.  */
   char * probe_module_arg;	/**< @brief Select probe module (default='tcp_synscan').  */
   char * probe_module_orig;	/**< @brief Select probe module original value given at command line.  */
   const char *probe_module_help; /**< @brief Select probe module help description.  */
-  char * output_module_arg;	/**< @brief Select output module (default='simple_file').  */
+  char * output_module_arg;	/**< @brief Select output module (default='csv').  */
   char * output_module_orig;	/**< @brief Select output module original value given at command line.  */
   const char *output_module_help; /**< @brief Select output module help description.  */
   char * probe_args_arg;	/**< @brief Arguments to pass to probe module.  */
@@ -137,6 +138,7 @@ struct gengetopt_args_info
   unsigned int source_ip_given ;	/**< @brief Whether source-ip was given.  */
   unsigned int gateway_mac_given ;	/**< @brief Whether gateway-mac was given.  */
   unsigned int interface_given ;	/**< @brief Whether interface was given.  */
+  unsigned int vpn_given ;	/**< @brief Whether vpn was given.  */
   unsigned int probe_module_given ;	/**< @brief Whether probe-module was given.  */
   unsigned int output_module_given ;	/**< @brief Whether output-module was given.  */
   unsigned int probe_args_given ;	/**< @brief Whether probe-args was given.  */