Merge pull request #311 from shripchenko/master

Implement ZMQ_TCP_ACCEPT_FILTER setsockopt() for listening TCP sockets. 

doc/zmq_setsockopt.txt

@@ -415,6 +415,22 @@ Default value:: -1 (leave to OS default)
 Applicable socket types:: all, when using TCP transports.
 
 
+ZMQ_TCP_ACCEPT_FILTER: Assign filters to allow new TCP connections
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Assign arbitrary number of filters that will be applied for each new TCP transport
+connection on a listening socket.
+If no filters applied, then TCP transport allows connections from any ip.
+If at least one filter is applied then new connection source ip should be matched.
+To clear all filters call zmq_setsockopt(socket, ZMQ_TCP_ACCEPT_FILTER, NULL, 0).
+Filter is a null-terminated string with ipv6 or ipv4 CIDR.
+
+[horizontal]
+Option value type:: binary data
+Option value unit:: N/A
+Default value:: no filters (allow from all)
+Applicable socket types:: all listening sockets, when using TCP transports.
+
+
 RETURN VALUE
 ------------
 The _zmq_setsockopt()_ function shall return zero if successful. Otherwise it

include/zmq.h

@@ -226,6 +226,7 @@ ZMQ_EXPORT int zmq_msg_set (zmq_msg_t *msg, int option, int optval);
 #define ZMQ_TCP_KEEPALIVE_CNT 35
 #define ZMQ_TCP_KEEPALIVE_IDLE 36
 #define ZMQ_TCP_KEEPALIVE_INTVL 37
+#define ZMQ_TCP_ACCEPT_FILTER 38
 
 
 /*  Message options                                                           */

src/options.cpp

@@ -287,6 +287,32 @@ int zmq::options_t::setsockopt (int option_, const void *optval_,
 #endif
             return 0;
         }
+
+    case ZMQ_TCP_ACCEPT_FILTER:
+        {
+            if (optvallen_ == 0 && optval_ == NULL) {
+                tcp_accept_filters.clear ();
+                return 0;
+            }
+            else
+            if (optvallen_ < 1 || optvallen_ > 255 || optval_ == NULL || *((const char*) optval_) == 0) {
+                errno = EINVAL;
+                return -1;
+            }
+            else {
+                std::string filter_str ((const char*) optval_, optvallen_);
+
+                tcp_address_mask_t filter;
+                int rc = filter.resolve (filter_str.c_str (), ipv4only ? true : false);
+                if (rc != 0) {
+                    errno = EINVAL;
+                    return -1;
+                }
+                tcp_accept_filters.push_back(filter);
+
+                return 0;
+            }
+        }
     }
     errno = EINVAL;
     return -1;

src/options.hpp

@@ -24,9 +24,11 @@
 #define __ZMQ_OPTIONS_HPP_INCLUDED__
 
 #include <string>
+#include <vector>
 
 #include "stddef.h"
 #include "stdint.hpp"
+#include "tcp_address.hpp"
 
 namespace zmq
 {
@@ -118,6 +120,10 @@ namespace zmq
         int tcp_keepalive_idle;
         int tcp_keepalive_intvl;
 
+        // TCP accept() filters
+        typedef std::vector <tcp_address_mask_t> tcp_accept_filters_t;
+        tcp_accept_filters_t tcp_accept_filters;
+
         //  ID of the socket.
         int socket_id;
     };

src/tcp_address.cpp

@@ -445,3 +445,105 @@ sa_family_t zmq::tcp_address_t::family () const
     return address.generic.sa_family;
 }
 
+zmq::tcp_address_mask_t::tcp_address_mask_t () :
+    tcp_address_t ()
+{
+    address_mask = -1;
+}
+
+const int zmq::tcp_address_mask_t::mask () const
+{
+    return address_mask;
+}
+
+int zmq::tcp_address_mask_t::resolve (const char *name_, bool ipv4only_)
+{
+    std::string addr_str;
+    std::string mask_str;
+
+    // Find '/' at the end that separates address from the cidr mask number.
+    // Allow empty mask clause and threat it like '/32' for ipv4 or '/128' for ipv6.
+    const char *delimiter = strrchr (name_, '/');
+    if (delimiter != NULL) {
+        addr_str.assign (name_, delimiter - name_);
+        mask_str.assign (delimiter + 1);
+        if (mask_str.empty ()) {
+            errno = EINVAL;
+            return -1;
+        }
+    }
+    else {
+        addr_str.assign (name_);
+    }
+
+    // Parse address part using standard routines.
+    int rc = tcp_address_t::resolve_hostname (addr_str.c_str (), ipv4only_);
+    if (rc != 0)
+        return rc;
+
+    // Parse the cidr mask number.
+    if (mask_str.empty ()) {
+        if (address.generic.sa_family == AF_INET6)
+            address_mask = 128;
+        else
+            address_mask = 32;
+    }
+    else
+    if (mask_str == "0") {
+        address_mask = 0;
+    }
+    else {
+        int mask = atoi (mask_str.c_str ());
+        if (
+            (mask < 1) ||
+            (address.generic.sa_family == AF_INET6 && mask > 128) ||
+            (address.generic.sa_family != AF_INET6 && mask > 32)
+        ) {
+            errno = EINVAL;
+            return -1;
+        }
+        address_mask = mask;
+    }
+
+    return 0;
+}
+
+const bool zmq::tcp_address_mask_t::match_address (const struct sockaddr *ss, socklen_t ss_len) const
+{
+    zmq_assert (ss != NULL && ss_len >= sizeof(struct sockaddr));
+
+    if (ss->sa_family != address.generic.sa_family)
+        return false;
+
+    if (address_mask > 0) {
+        int mask;
+        const int8_t *our_bytes, *their_bytes;
+        if (ss->sa_family == AF_INET6) {
+            zmq_assert (ss_len == sizeof (struct sockaddr_in6));
+            their_bytes = (const int8_t *) &(((const struct sockaddr_in6 *) ss)->sin6_addr);
+            our_bytes = (const int8_t *) &address.ipv6.sin6_addr;
+            mask = sizeof (struct in6_addr) * 8;
+        }
+        else {
+            zmq_assert (ss_len == sizeof (struct sockaddr_in));
+            their_bytes = (const int8_t *) &(((const struct sockaddr_in *) ss)->sin_addr);
+            our_bytes = (const int8_t *) &address.ipv4.sin_addr;
+            mask = sizeof (struct in_addr) * 8;
+        }
+        if (address_mask < mask) mask = address_mask;
+
+        int full_bytes = mask / 8;
+        if (full_bytes) {
+            if (memcmp(our_bytes, their_bytes, full_bytes))
+                return false;
+        }
+
+        int last_byte_bits = (0xffU << (8 - (mask % 8))) & 0xffU;
+        if (last_byte_bits) {
+            if ((their_bytes[full_bytes] & last_byte_bits) != (our_bytes[full_bytes] & last_byte_bits))
+                return false;
+        }
+    }
+
+    return true;
+}

src/tcp_address.hpp

@@ -55,7 +55,7 @@ namespace zmq
         const sockaddr *addr () const;
         socklen_t addrlen () const;
 
-    private:
+    protected:
 
         int resolve_nic_name (const char *nic_, bool ipv4only_);
         int resolve_interface (const char *interface_, bool ipv4only_);
@@ -66,12 +66,28 @@ namespace zmq
             sockaddr_in ipv4;
             sockaddr_in6 ipv6;
         } address;
+    };
+
+    class tcp_address_mask_t : public tcp_address_t
+    {
+    public:
+
+        tcp_address_mask_t ();
+
+        // This function enhances tcp_address_t::resolve() with ability to parse
+        // additional cidr-like(/xx) mask value at the end of the name string.
+        // Works only with remote hostnames.
+        int resolve (const char* name_, bool ipv4only_);
 
-        tcp_address_t (const tcp_address_t&);
-        const tcp_address_t &operator = (const tcp_address_t&);
+        const int mask () const;
+
+        const bool match_address (const struct sockaddr *sa, socklen_t ss_len) const;
+
+    private:
+
+        int address_mask;
     };
-    
+
 }
 
 #endif
-

src/tcp_listener.cpp

@@ -235,7 +235,11 @@ zmq::fd_t zmq::tcp_listener_t::accept ()
 {
     //  Accept one connection and deal with different failure modes.
     zmq_assert (s != retired_fd);
-    fd_t sock = ::accept (s, NULL, NULL);
+
+    struct sockaddr_storage ss = {0};
+    socklen_t ss_len = sizeof (ss);
+    fd_t sock = ::accept (s, (struct sockaddr *) &ss, &ss_len);
+
 #ifdef ZMQ_HAVE_WINDOWS
     if (sock == INVALID_SOCKET) {
         wsa_assert (WSAGetLastError () == WSAEWOULDBLOCK ||
@@ -250,6 +254,28 @@ zmq::fd_t zmq::tcp_listener_t::accept ()
         return retired_fd;
     }
 #endif
+
+    if (!options.tcp_accept_filters.empty ()) {
+        bool matched = false;
+//ss_len = 1;
+        for (options_t::tcp_accept_filters_t::size_type i = 0; i != options.tcp_accept_filters.size (); ++i) {
+            if (options.tcp_accept_filters[i].match_address ((struct sockaddr *) &ss, ss_len)) {
+                matched = true;
+                break;
+            }
+        }
+        if (!matched) {
+#ifdef ZMQ_HAVE_WINDOWS
+            int rc = closesocket (sock);
+            wsa_assert (rc != SOCKET_ERROR);
+#else
+            int rc = ::close (sock);
+            errno_assert (rc == 0);
+#endif
+            return retired_fd;
+        }
+    }
+
     return sock;
 }
 

src/tcp_listener.hpp

@@ -62,7 +62,8 @@ namespace zmq
 
         //  Accept the new connection. Returns the file descriptor of the
         //  newly created connection. The function may return retired_fd
-        //  if the connection was dropped while waiting in the listen backlog.
+        //  if the connection was dropped while waiting in the listen backlog
+        //  or was denied because of accept filters.
         fd_t accept ();
 
         //  Address to listen on.