added new method rsGetHostByName to use gethostbyname_r for re-entrant calls. Updated dnsresolver and extaddrfinder to use it. Suggestion by GuessWho #125

libretroshare/src/util/dnsresolver.cc

@@ -62,24 +62,32 @@ void *solveDNSEntries(void *p)
 
 		if(!next_call.empty())
 		{
-			hostent *pHost = gethostbyname(next_call.c_str());
+                    in_addr in ;
+                    
+                    bool succeed = rsGetHostByName(next_call.c_str(),in);
                     
 		    {
 			    RsStackMutex mut(dnsr->_rdnsMtx) ;
 
 			    DNSResolver::AddrInfo &info = (*dnsr->_addr_map)[next_call];
 
-				if(pHost) 
+			    if(succeed) 
 			    {
 				    info.state = DNSResolver::DNS_HAVE ;
 				    // IPv4 for the moment.
 				    struct sockaddr_in *addrv4p = (struct sockaddr_in *) &(info.addr);
 				    addrv4p->sin_family = AF_INET;
-					addrv4p->sin_addr.s_addr  = *(unsigned long*) (pHost->h_addr);
+				    addrv4p->sin_addr= in ;
 				    addrv4p->sin_port = htons(0);
+                    
+                    std::cerr << "LOOKUP succeeded: " << next_call.c_str() << " => " << rs_inet_ntoa(addrv4p->sin_addr) << std::endl;
 			    }
 			    else
+				{
 					info.state = DNSResolver::DNS_LOOKUP_ERROR ;
+                    
+                    			std::cerr << "DNSResolver: lookup error for address \"" << next_call.c_str() << "\"" << std::endl;
+				}
 		    }
 		}
 	}

libretroshare/src/util/extaddrfinder.cc

@@ -2,6 +2,7 @@
 
 #include "pqi/pqinetwork.h"
 #include "util/rsstring.h"
+#include "util/rsmemory.h"
 
 #ifndef WIN32
 #include <netdb.h>
@@ -58,7 +59,6 @@ static void getPage(const std::string& server_name,std::string& page)
 	int sockfd,n=0;                   // socket descriptor
 	struct sockaddr_in serveur;       // server's parameters
 	memset(&serveur.sin_zero, 0, sizeof(serveur.sin_zero));
-	struct hostent *hostinfo=NULL;    // structure for storing the server's ip
 
 	char buf[1024];
 	char request[1024];
@@ -78,20 +78,21 @@ static void getPage(const std::string& server_name,std::string& page)
 
 	// get server's ipv4 adress
 
-	hostinfo = gethostbyname(server_name.c_str()); 
+    	in_addr in ;
         
-	if (hostinfo == NULL) /* l'hôte n'existe pas */
+	if(!rsGetHostByName(server_name.c_str(),in))  /* l'hôte n'existe pas */
 	{
 		std::cerr << "ExtAddrFinder: Unknown host " << server_name << std::endl;
 		unix_close(sockfd);
 		return ;
 	}
-	serveur.sin_addr = *(struct in_addr*) hostinfo->h_addr; 
+	serveur.sin_addr = in ;
 	serveur.sin_port = htons(80);
 
 #ifdef EXTADDRSEARCH_DEBUG
 	printf("Connection attempt\n");
 #endif
+    	std::cerr << "ExtAddrFinder: resolved hostname " << server_name << " to " << rs_inet_ntoa(in) << std::endl;
 
 	if(unix_connect(sockfd,(struct sockaddr *)&serveur, sizeof(serveur)) == -1)
 	{

libretroshare/src/util/rsmemory.h

@@ -25,10 +25,17 @@ class RsTemporaryMemory
     RsTemporaryMemory(size_t s)
     {
 	    _mem = (unsigned char *)malloc(s) ;
+
+	    if(_mem)
+		    _size = s ;
+	    else
+		    _size = 0 ;
     }
 
     operator unsigned char *() { return _mem ; }
     
+    size_t size() const { return _size ; }
+
     ~RsTemporaryMemory()
     {
 	    if(_mem != NULL)
@@ -40,6 +47,7 @@ class RsTemporaryMemory
 
 private:
     unsigned char *_mem ;
+    size_t _size ;
 
     // make it noncopyable
     RsTemporaryMemory& operator=(const RsTemporaryMemory&) { return *this ;}

libretroshare/src/util/rsnet.cc

@@ -26,6 +26,7 @@
 #include "util/rsnet.h"
 #include "util/rsthreads.h"
 #include "util/rsstring.h"
+#include "util/rsmemory.h"
 
 #ifdef WINDOWS_SYS
 #else
@@ -72,6 +73,36 @@ void sockaddr_clear(struct sockaddr_in *addr)
         addr->sin_family = AF_INET;
 }
 
+bool rsGetHostByName(const std::string& hostname, in_addr& returned_addr)
+{
+    RsTemporaryMemory mem(8192) ;
+
+    if(!mem)
+    {
+	    std::cerr << __PRETTY_FUNCTION__ << ": Cannot allocate memory!" << std::endl;
+	    return false; // Do something.
+    }
+
+    int error = 0;
+    struct hostent pHost;
+    struct hostent *result;
+
+    if(gethostbyname_r(hostname.c_str(), &pHost, (char*)(unsigned char*)mem, mem.size(), &result, &error) != 0)
+    {
+	    std::cerr << __PRETTY_FUNCTION__ << ": cannot call gethostname_r. Internal error reported. Check buffer size." << std::endl;
+	    return false ;
+    }
+    if(!result)
+    {
+	    std::cerr << __PRETTY_FUNCTION__ << ": gethostname_r returned null result." << std::endl;
+	    return false ;
+    }
+    // Use contents of result.
+
+    returned_addr.s_addr = *(unsigned long*) (result->h_addr);
+    
+    return true ;
+}
 
 bool    isValidNet(const struct in_addr *addr)
 {

libretroshare/src/util/rsnet.h

@@ -70,6 +70,9 @@ bool isLoopbackNet(const struct in_addr *addr);
 bool isPrivateNet(const struct in_addr *addr);
 bool isExternalNet(const struct in_addr *addr);
 
+// uses a re-entrant version of gethostbyname
+bool rsGetHostByName(const std::string& hostname, in_addr& returned_addr) ;
+
 std::ostream& operator<<(std::ostream& o,const struct sockaddr_in&) ;
 
 /* thread-safe version of inet_ntoa */