swrap: add support for SOCKET_WRAPPER_IPV4_NETWORK=10.53.57.0

With this 10.53.57.XX/8 addresses are used instead of
127.0.0.XX/8. Note the broadcast address is 127.255.255.255
or 10.255.255.255 (and not 10.53.57.255!).

Some applications, e.g. Samba have some special behavior for
loopback addresses.

This allows more realistic tests and triggers the more common
code paths.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>

3 files changed, 42 insertions, 10 deletions

diff --git a/doc/socket_wrapper.1 b/doc/socket_wrapper.1
index b62fb6f..e244f10 100644
--- a/doc/socket_wrapper.1
+++ b/doc/socket_wrapper.1
@@ -75,9 +75,14 @@ Ability to capture network traffic in pcap format\&.
 The user defines a directory where to put all the unix sockets using the environment variable "SOCKET_WRAPPER_DIR=/path/to/socket_dir"\&. When a server opens a port or a client wants to connect, socket_wrapper will translate IP addresses to a special socket_wrapper name and look for the relevant Unix socket in the SOCKET_WRAPPER_DIR\&.
 .RE
 .PP
+\fBSOCKET_WRAPPER_IPV4_NETWORK\fR
+.RS 4
+By default the loopback IPv4 network "127\&.0\&.0\&.0/8" and the "127\&.0\&.0\&.x" can be used\&. In order to make more realistic testing possible it is possible to use the "10\&.0\&.0\&.0/8" IPv4 network instead\&. But note within "10\&.0\&.0\&.0/8" only "10\&.53\&.57\&.<ID>" can be used, but the broadcast address is "10\&.255\&.255\&.255"\&. The following two value are allowed: SOCKET_WRAPPER_IPV4_NETWORK="127\&.0\&.0\&.0" (the default) and SOCKET_WRAPPER_IPV4_NETWORK="10\&.53\&.57\&.0"\&.
+.RE
+.PP
 \fBSOCKET_WRAPPER_DEFAULT_IFACE\fR
 .RS 4
-Additionally, the default interface to be used by an application is defined with "SOCKET_WRAPPER_DEFAULT_IFACE=<ID>" where the valid range for <ID> starts with 1 (the default) and ends with 64\&. This is analogous to use the IPv4 addresses "127\&.0\&.0\&.<ID>" or IPv6 addresses "fd00::5357:5f<IDx>" (where <IDx> is a hexadecimal presentation of <ID>)\&. You should always set the default interface\&. If you listen on INADDR_ANY then it will use the default interface to listen on\&.
+Additionally, the default interface to be used by an application is defined with "SOCKET_WRAPPER_DEFAULT_IFACE=<ID>" where the valid range for <ID> starts with 1 (the default) and ends with 64\&. This is analogous to use the IPv4 addresses "127\&.0\&.0\&.<ID>"/"10\&.53\&.57\&.<ID>" or IPv6 addresses "fd00::5357:5f<IDx>" (where <IDx> is a hexadecimal presentation of <ID>)\&. You should always set the default interface\&. If you listen on INADDR_ANY then it will use the default interface to listen on\&.
 .RE
 .PP
 \fBSOCKET_WRAPPER_PCAP_FILE\fR
diff --git a/doc/socket_wrapper.1.txt b/doc/socket_wrapper.1.txt
index 15b99bf..c00d582 100644
--- a/doc/socket_wrapper.1.txt
+++ b/doc/socket_wrapper.1.txt
@@ -36,14 +36,26 @@ opens a port or a client wants to connect, socket_wrapper will translate IP
 addresses to a special socket_wrapper name and look for the relevant Unix
 socket in the SOCKET_WRAPPER_DIR.
 
+*SOCKET_WRAPPER_IPV4_NETWORK*::
+
+By default the loopback IPv4 network "127.0.0.0/8" and the
+"127.0.0.x" can be used. In order to make more realistic testing
+possible it is possible to use the "10.0.0.0/8" IPv4 network instead.
+But note within "10.0.0.0/8" only "10.53.57.<ID>" can be used,
+but the broadcast address is "10.255.255.255".
+The following two value are allowed:
+SOCKET_WRAPPER_IPV4_NETWORK="127.0.0.0" (the default) and
+SOCKET_WRAPPER_IPV4_NETWORK="10.53.57.0".
+
 *SOCKET_WRAPPER_DEFAULT_IFACE*::
 
 Additionally, the default interface to be used by an application is defined with
 "SOCKET_WRAPPER_DEFAULT_IFACE=<ID>" where the valid range for <ID> starts with 1
 (the default) and ends with 64. This is analogous to use the IPv4 addresses
-"127.0.0.<ID>" or IPv6 addresses "fd00::5357:5f<IDx>" (where <IDx> is a
-hexadecimal presentation of <ID>). You should always set the default interface.
-If you listen on INADDR_ANY then it will use the default interface to listen on.
+"127.0.0.<ID>"/"10.53.57.<ID>" or IPv6 addresses "fd00::5357:5f<IDx>" (where
+<IDx> is a hexadecimal presentation of <ID>). You should always set the default
+interface. If you listen on INADDR_ANY then it will use the default interface to
+listen on.
 
 *SOCKET_WRAPPER_PCAP_FILE*::
 
diff --git a/src/socket_wrapper.c b/src/socket_wrapper.c
index d05182f..cee7c51 100644
--- a/src/socket_wrapper.c
+++ b/src/socket_wrapper.c
@@ -1193,13 +1193,18 @@ static void swrap_bind_symbol_all(void)
  *********************************************************/
 
 /*
- * For now we return 127.0.0.0
+ * We return 127.0.0.0 (default) or 10.53.57.0.
+ *
+ * This can be controlled by:
+ * SOCKET_WRAPPER_IPV4_NETWORK=127.0.0.0 (default)
+ * or
+ * SOCKET_WRAPPER_IPV4_NETWORK=10.53.57.0
  */
 static in_addr_t swrap_ipv4_net(void)
 {
 	static int initialized;
 	static in_addr_t hv;
-	const char *net_str = "127.0.0.0";
+	const char *net_str = NULL;
 	struct in_addr nv;
 	int ret;
 
@@ -1208,6 +1213,11 @@ static in_addr_t swrap_ipv4_net(void)
 	}
 	initialized = 1;
 
+	net_str = getenv("SOCKET_WRAPPER_IPV4_NETWORK");
+	if (net_str == NULL) {
+		net_str = "127.0.0.0";
+	}
+
 	ret = inet_pton(AF_INET, net_str, &nv);
 	if (ret <= 0) {
 		SWRAP_LOG(SWRAP_LOG_ERROR,
@@ -1237,7 +1247,7 @@ static in_addr_t swrap_ipv4_net(void)
 }
 
 /*
- * This returns 127.255.255.255
+ * This returns 127.255.255.255 or 10.255.255.255
  */
 static in_addr_t swrap_ipv4_bcast(void)
 {
@@ -1250,7 +1260,7 @@ static in_addr_t swrap_ipv4_bcast(void)
 }
 
 /*
- * This returns 127.0.0.${iface}
+ * This returns 127.0.0.${iface} or 10.53.57.${iface}
  */
 static in_addr_t swrap_ipv4_iface(unsigned int iface)
 {
@@ -1846,12 +1856,17 @@ static int convert_in_un_remote(struct socket_info *si, const struct sockaddr *i
 			type = a_type;
 			iface = socket_wrapper_default_iface();
 		} else if (b_type && addr == sw_bcast_addr) {
-			/* 127.255.255.255 only udp */
+			/*
+			 * 127.255.255.255
+			 * or
+			 * 10.255.255.255
+			 * only udp
+			 */
 			is_bcast = 1;
 			type = b_type;
 			iface = socket_wrapper_default_iface();
 		} else if ((addr & 0xFFFFFF00) == sw_net_addr) {
-			/* 127.0.0.X */
+			/* 127.0.0.X or 10.53.57.X */
 			is_bcast = 0;
 			type = u_type;
 			iface = (addr & 0x000000FF);