Add server option 'JsonRpcWebApiAllowedSubnet' to restrict access to JSON-RPC API based on client IP address

developer_tools/vpnserver-jsonrpc-clients/README.html

@@ -30,6 +30,7 @@
 <ul>
 <li>Older versions of SoftEther VPN before June 2019 don't support JSON-RPC APIs.</li>
 <li>If you want to completely disable the JSON-RPC on your VPN Server, set the <code>DisableJsonRpcWebApi</code> variable to <code>true</code> on the <code>vpn_server.config</code>.</li>
+<li>You may also restrict access to JSON-RPC API to a specific subnet, e.g. your internal network, by setting the <code>JsonRpcWebApiAllowedSubnet</code> variable to, for example, <code>192.168.0.0/16</code>.</li>
 </ul>
 <h3 id="json-rpc-specification">JSON-RPC specification</h3>
 <p>You must use HTTPS 1.1 <code>POST</code> method to call each of JSON-RPC APIs.<br />

developer_tools/vpnserver-jsonrpc-clients/README.md

@@ -25,6 +25,7 @@ https://<vpn_server_hostname>:<port>/api/
 
   - Older versions of SoftEther VPN before June 2019 don't support JSON-RPC APIs.
   - If you want to completely disable the JSON-RPC on your VPN Server, set the `DisableJsonRpcWebApi` variable to `true` on the `vpn_server.config`.
+  - You may also restrict access to JSON-RPC API to a specific subnet, e.g. your internal network, by setting the `JsonRpcWebApiAllowedSubnet` variable to, for example, `192.168.0.0/16`.
 
 
 ### JSON-RPC specification

developer_tools/vpnserver-jsonrpc-codegen/Templates/doc.txt

@@ -25,6 +25,7 @@ https://<vpn_server_hostname>:<port>/api/
 
   - Older versions of SoftEther VPN before June 2019 don't support JSON-RPC APIs.
   - If you want to completely disable the JSON-RPC on your VPN Server, set the `DisableJsonRpcWebApi` variable to `true` on the `vpn_server.config`.
+  - You may also restrict access to JSON-RPC API to a specific subnet, e.g. your internal network, by setting the `JsonRpcWebApiAllowedSubnet` variable to, for example, `192.168.0.0/16`.
 
 
 ### JSON-RPC specification

src/Cedar/Protocol.c

@@ -5763,6 +5763,7 @@ bool ServerDownloadSignature(CONNECTION *c, char **error_detail_str)
 	UINT num = 0, max = 19;
 	SERVER *server;
 	char *vpn_http_target = HTTP_VPN_TARGET2;
+	bool disableJsonRpcWebApi;
 	// Validate arguments
 	if (c == NULL)
 	{
@@ -5773,6 +5774,15 @@ bool ServerDownloadSignature(CONNECTION *c, char **error_detail_str)
 
 	s = c->FirstSock;
 
+	disableJsonRpcWebApi = server->DisableJsonRpcWebApi;
+	if (!disableJsonRpcWebApi && !IsZeroIP(&server->JsonRpcWebApiAllowedSubnetAddr)
+				&& !IsZeroIP(&server->JsonRpcWebApiAllowedSubnetMask)) {
+		// restrict JSON-RPC Web API to specified subnet only
+		if (!IsInSameNetwork(&s->RemoteIP, &server->JsonRpcWebApiAllowedSubnetAddr, &server->JsonRpcWebApiAllowedSubnetMask)) {
+			disableJsonRpcWebApi = true;
+		}
+	}
+
 	while (true)
 	{
 		bool not_found_error = false;
@@ -5805,7 +5815,7 @@ bool ServerDownloadSignature(CONNECTION *c, char **error_detail_str)
 			// Receive the data since it's POST
 			data_size = GetContentLength(h);
 
-			if (server->DisableJsonRpcWebApi == false)
+			if (disableJsonRpcWebApi == false)
 			{
 				if (StrCmpi(h->Target, "/api") == 0 || StrCmpi(h->Target, "/api/") == 0)
 				{
@@ -5891,7 +5901,7 @@ bool ServerDownloadSignature(CONNECTION *c, char **error_detail_str)
 		}
 		else if (StrCmpi(h->Method, "OPTIONS") == 0)
 		{
-			if (server->DisableJsonRpcWebApi == false)
+			if (disableJsonRpcWebApi == false)
 			{
 				if (StrCmpi(h->Target, "/api") == 0 || StrCmpi(h->Target, "/api/") == 0 || StartWith(h->Target, "/admin"))
 				{
@@ -5962,7 +5972,7 @@ bool ServerDownloadSignature(CONNECTION *c, char **error_detail_str)
 					BUF *b = NULL;
 					*error_detail_str = "HTTP_ROOT";
 
-					if (server->DisableJsonRpcWebApi == false)
+					if (disableJsonRpcWebApi == false)
 					{
 						b = ReadDump("|wwwroot/index.html");
 					}
@@ -6042,7 +6052,7 @@ bool ServerDownloadSignature(CONNECTION *c, char **error_detail_str)
 
 					if (b == false)
 					{
-						if (server->DisableJsonRpcWebApi == false)
+						if (disableJsonRpcWebApi == false)
 						{
 							if (StartWith(h->Target, "/api?") || StartWith(h->Target, "/api/") || StrCmpi(h->Target, "/api") == 0)
 							{

src/Cedar/Server.c

@@ -30,6 +30,7 @@
 #include "Mayaqua/Internat.h"
 #include "Mayaqua/Memory.h"
 #include "Mayaqua/Microsoft.h"
+#include "Mayaqua/Network.h"
 #include "Mayaqua/Object.h"
 #include "Mayaqua/OS.h"
 #include "Mayaqua/Pack.h"
@@ -6032,6 +6033,15 @@ void SiLoadServerCfg(SERVER *s, FOLDER *f)
 		// Disable JSON-RPC Web API
 		s->DisableJsonRpcWebApi = CfgGetBool(f, "DisableJsonRpcWebApi");
 
+		char tmpaddr[MAX_PATH];
+		if (CfgGetStr(f, "JsonRpcWebApiAllowedSubnet", tmpaddr, sizeof(tmpaddr))) {
+			IP _subnet, _mask;
+			if (ParseIpAndMask46(tmpaddr, &_subnet, &_mask)) {
+				s->JsonRpcWebApiAllowedSubnetAddr = _subnet;
+				s->JsonRpcWebApiAllowedSubnetMask = _mask;
+			}
+		}
+
 		// Bits of Diffie-Hellman parameters
 		c->DhParamBits = CfgGetInt(f, "DhParamBits");
 		if (c->DhParamBits == 0)
@@ -6365,6 +6375,11 @@ void SiWriteServerCfg(FOLDER *f, SERVER *s)
 
 		// Disable JSON-RPC Web API
 		CfgAddBool(f, "DisableJsonRpcWebApi", s->DisableJsonRpcWebApi);
+
+		char tmpaddr[MAX_PATH];
+		IPAndMaskToStr(tmpaddr, sizeof(tmpaddr),
+			&s->JsonRpcWebApiAllowedSubnetAddr, &s->JsonRpcWebApiAllowedSubnetMask);
+		CfgAddStr(f, "JsonRpcWebApiAllowedSubnet", tmpaddr);
 	}
 	Unlock(c->lock);
 }

src/Cedar/Server.h

@@ -276,6 +276,9 @@ struct SERVER
 	IP ListenIP;						// Listen IP
 	bool StrictSyslogDatetimeFormat;	// Make syslog datetime format strict RFC3164
 	bool DisableJsonRpcWebApi;					// Disable JSON-RPC Web API
+
+	IP JsonRpcWebApiAllowedSubnetAddr;  // If set, allow access to JSON-RPC Web API from
+	IP JsonRpcWebApiAllowedSubnetMask;  //   this subnet only
 };
 
 

src/Mayaqua/Network.c

@@ -6976,6 +6976,18 @@ void IPToStr6Inner(char *str, IP *ip)
 	}
 }
 
+// Format IP and subnet mask as "<ip>/<masksize>"
+void IPAndMaskToStr(char *str, UINT size, IP *ip, IP *subnet)
+{
+	int iplen;
+	UINT masksize;
+
+	IPToStr(str, size, ip);
+	iplen = StrLen(str);
+	masksize = SubnetMaskToInt(subnet);
+	Format(str + iplen, size - iplen, "/%d", masksize);
+}
+
 // Convert the string to an IP address
 bool StrToIP6(IP *ip, char *str)
 {

src/Mayaqua/Network.h

@@ -1270,6 +1270,7 @@ void IPToStr6(char *str, UINT size, IP *ip);
 void IP6AddrToStr(char *str, UINT size, IPV6_ADDR *addr);
 void IPToStr6Array(char *str, UINT size, UCHAR *bytes);
 void IPToStr6Inner(char *str, IP *ip);
+void IPAndMaskToStr(char *str, UINT size, IP *ip, IP *subnet);
 void IntToSubnetMask6(IP *ip, UINT i);
 void IPAnd6(IP *dst, IP *a, IP *b);
 void GetAllRouterMulticastAddress6(IP *ip);