Have NetBlock::next return the socklen.

This matters on OS X; with the wrong size, connect scans give "Invalid
argument".
Reported by Jesper Kückelhahn.
http://seclists.org/nmap-dev/2013/q1/84

TargetGroup.cc

@@ -278,7 +278,7 @@ NetBlockIPv4Ranges::NetBlockIPv4Ranges() {
   }
 }
 
-bool NetBlockIPv4Ranges::next(struct sockaddr_storage *ss) {
+bool NetBlockIPv4Ranges::next(struct sockaddr_storage *ss, size_t *sslen) {
   struct sockaddr_in *sin;
   unsigned int i;
 
@@ -303,6 +303,7 @@ bool NetBlockIPv4Ranges::next(struct sockaddr_storage *ss) {
   sin->sin_len = sizeof(*sin);
 #endif
   sin->sin_addr.s_addr = htonl((this->counter[0] << 24) | (this->counter[1] << 16) | (this->counter[2] << 8) | this->counter[3]);
+  *sslen = sizeof(*sin);
 
   for (i = 0; i < 4; i++) {
     bool carry;
@@ -451,7 +452,7 @@ static bool ipv6_equal(const struct in6_addr *a, const struct in6_addr *b) {
   return memcmp(a->s6_addr, b->s6_addr, 16) == 0;
 }
 
-bool NetBlockIPv6Netmask::next(struct sockaddr_storage *ss) {
+bool NetBlockIPv6Netmask::next(struct sockaddr_storage *ss, size_t *sslen) {
   struct sockaddr_in6 *sin6;
 
   if (this->exhausted)
@@ -463,6 +464,7 @@ bool NetBlockIPv6Netmask::next(struct sockaddr_storage *ss) {
 #ifdef SIN_LEN
   sin6->sin6_len = sizeof(*sin6);
 #endif
+  *sslen = sizeof(*sin6);
 
   if (this->addr.sin6_scope_id != 0)
     sin6->sin6_scope_id = this->addr.sin6_scope_id;
@@ -631,7 +633,7 @@ NetBlockHostname::NetBlockHostname(const char *hostname, int af) {
   this->bits = -1;
 }
 
-bool NetBlockHostname::next(struct sockaddr_storage *ss) {
+bool NetBlockHostname::next(struct sockaddr_storage *ss, size_t *sslen) {
   assert(false);
   return false;
 }

TargetGroup.h

@@ -126,7 +126,7 @@ class NetBlock {
 
   bool is_resolved_address(const struct sockaddr_storage *ss) const;
 
-  virtual bool next(struct sockaddr_storage *ss) = 0;
+  virtual bool next(struct sockaddr_storage *ss, size_t *sslen) = 0;
   virtual void apply_netmask(int bits) = 0;
   virtual std::string str() const = 0;
 };
@@ -137,7 +137,7 @@ class NetBlockIPv4Ranges : public NetBlock {
 
   NetBlockIPv4Ranges();
 
-  bool next(struct sockaddr_storage *ss);
+  bool next(struct sockaddr_storage *ss, size_t *sslen);
   void apply_netmask(int bits);
   std::string str() const;
 
@@ -149,7 +149,7 @@ class NetBlockIPv6Netmask : public NetBlock {
 public:
   void set_addr(const struct sockaddr_in6 *addr);
 
-  bool next(struct sockaddr_storage *ss);
+  bool next(struct sockaddr_storage *ss, size_t *sslen);
   void apply_netmask(int bits);
   std::string str() const;
 
@@ -169,7 +169,7 @@ class NetBlockHostname : public NetBlock {
 
   NetBlock *resolve() const;
 
-  bool next(struct sockaddr_storage *ss);
+  bool next(struct sockaddr_storage *ss, size_t *sslen);
   void apply_netmask(int bits);
   std::string str() const;
 };

targets.cc

@@ -353,8 +353,7 @@ int TargetGroup::get_next_host(struct sockaddr_storage *ss, size_t *sslen) {
     delete netblock_hostname;
   }
 
-  *sslen = sizeof(*ss);
-  if (this->netblock->next(ss))
+  if (this->netblock->next(ss, sslen))
     return 0;
   else
     return -1;