Break out resolve and resolve_numeric.

Besides the confusingness of the nodns argument being negatively
phrased, it had the value 0 in every existing call. Split out the nodns
special case into a separate function resolve_numeric.

This also has the side effect of changing the number of parameters to
the resolve function, which will cause a compile error for any calls I
might have missed changing when I changed the return code meaning in the
previous commit.

Ncat has its own copy of resolve, which obeys the global o.nodns rather
than a parameter. I'm leaving that alone for now. But give it the same
resolve_internal function, and make resolve call it with different flags
depending on the value of o.nodns.

idle_scan.cc

@@ -339,7 +339,7 @@ static void initialize_idleproxy(struct idle_proxy_info *proxy, char *proxyName,
   }
 
   proxy->host.setHostName(name);
-  if (resolve(name, 0, 0, &ss, &sslen, o.pf()) != 0) {
+  if (resolve(name, 0, &ss, &sslen, o.pf()) != 0) {
     fatal("Could not resolve idle scan zombie host: %s", name);
   }
   proxy->host.setTargetSockAddr(&ss, sslen);

libnetutil/netutil.cc

@@ -374,15 +374,10 @@ after:
   return(d - data);
 }
 
-/* Tries to resolve the given name (or literal IP) into a sockaddr structure.
-   - Parameter "hostname" is the name to be resolved.
-   - Parameter "port" sets the port in each returned address structure
-     (you can safely pass 0 for the port if you don't care)
-   - Parameter "nodns": If set, it means that the supplied hostname is actually a
-     numeric IP address. The flag prevents any type of name resolution service
-     from being called. In 99% of the cases this should be 0.
-   Returns 0 on success, or a getaddrinfo return code on failure. */
-int resolve(const char *hostname, u16 port, int nodns, struct sockaddr_storage *ss, size_t *sslen, int af){
+/* Internal helper for resolve and resolve_numeric. addl_flags is ored into
+   hints.ai_flags, so you can add AI_NUMERICHOST. */
+static int resolve_internal(const char *hostname, u16 port,
+  struct sockaddr_storage *ss, size_t *sslen, int af, int addl_flags) {
   struct addrinfo hints;
   struct addrinfo *result;
   char portbuf[16];
@@ -395,8 +390,7 @@ int resolve(const char *hostname, u16 port, int nodns, struct sockaddr_storage *
   memset(&hints, 0, sizeof(hints));
   hints.ai_family = af;
   hints.ai_socktype = SOCK_DGRAM;
-  if (nodns)
-    hints.ai_flags |= AI_NUMERICHOST;
+  hints.ai_flags |= addl_flags;
 
   /* Make the port number a string to give to getaddrinfo. */
   rc = Snprintf(portbuf, sizeof(portbuf), "%hu", port);
@@ -414,6 +408,23 @@ int resolve(const char *hostname, u16 port, int nodns, struct sockaddr_storage *
   return 0;
 }
 
+/* Resolves the given hostname or IP address with getaddrinfo, and stores the
+   first result (if any) in *ss and *sslen. The value of port will be set in the
+   appropriate place in *ss; set to 0 if you don't care. af may be AF_UNSPEC, in
+   which case getaddrinfo may return e.g. both IPv4 and IPv6 results; which one
+   is first depends on the system configuration. Returns 0 on success, or a
+   getaddrinfo return code (suitable for passing to gai_strerror) on failure.
+   *ss and *sslen are always defined when this function returns 0. */
+int resolve(const char *hostname, u16 port, struct sockaddr_storage *ss, size_t *sslen, int af) {
+  return resolve_internal(hostname, port, ss, sslen, af, 0);
+}
+
+/* As resolve, but do not do DNS resolution of hostnames; the first argument
+   must be the string representation of a numeric IP address. */
+int resolve_numeric(const char *ip, u16 port, struct sockaddr_storage *ss, size_t *sslen, int af) {
+  return resolve_internal(ip, port, ss, sslen, af, AI_NUMERICHOST);
+}
+
 /*
  * Returns 1 if this is a reserved IP address, where "reserved" means
  * either a private address, non-routable address, or even a non-reserved

libnetutil/netutil.h

@@ -157,15 +157,18 @@ int netutil_error(const char *str, ...)
    contain a newline character at the end. */
 int parse_ip_options(const char *txt, u8 *data, int datalen, int* firsthopoff, int* lasthopoff, char *errstr, size_t errstrlen);
 
-/* Tries to resolve the given name (or literal IP) into a sockaddr structure.
-   - Parameter "hostname" is the name to be resolved.
-   - Parameter "port" sets the port in each returned address structure
-     (you can safely pass 0 for the port if you don't care)
-   - Parameter "nodns": If set, it means that the supplied hostname is actually a
-     numeric IP address. The flag prevents any type of name resolution service
-     from being called. In 99% of the cases this should be 0.
-   Returns 0 on success, or a getaddrinfo return code on failure. */
-int resolve(const char *hostname, u16 port, int nodns, struct sockaddr_storage *ss, size_t *sslen, int af);
+/* Resolves the given hostname or IP address with getaddrinfo, and stores the
+   first result (if any) in *ss and *sslen. The value of port will be set in the
+   appropriate place in *ss; set to 0 if you don't care. af may be AF_UNSPEC, in
+   which case getaddrinfo may return e.g. both IPv4 and IPv6 results; which one
+   is first depends on the system configuration. Returns 0 on success, or a
+   getaddrinfo return code (suitable for passing to gai_strerror) on failure.
+   *ss and *sslen are always defined when this function returns 0. */
+int resolve(const char *hostname, u16 port, struct sockaddr_storage *ss, size_t *sslen, int af);
+
+/* As resolve, but do not do DNS resolution of hostnames; the first argument
+   must be the string representation of a numeric IP address. */
+int resolve_numeric(const char *ip, u16 port, struct sockaddr_storage *ss, size_t *sslen, int af);
 
 /*
  * Returns 1 if this is a reserved IP address, where "reserved" means

ncat/ncat_core.c

@@ -180,25 +180,24 @@ void options_init(void)
 #endif
 }
 
-/* Tries to resolve the given name (or literal IP) into a sockaddr structure.
-   Pass 0 for the port if you don't care. Returns 0 on success, or a getaddrinfo
-   return code on error. */
-int resolve(char *hostname, unsigned short port,
-            struct sockaddr_storage *ss, size_t *sslen, int af)
+/* Internal helper for resolve and resolve_numeric. addl_flags is ored into
+   hints.ai_flags, so you can add AI_NUMERICHOST. */
+static int resolve_internal(const char *hostname, unsigned short port,
+    struct sockaddr_storage *ss, size_t *sslen, int af, int addl_flags)
 {
     struct addrinfo hints;
     struct addrinfo *result;
     char portbuf[16];
-    int rc;
+    size_t rc=0;
 
+    assert(hostname);
     assert(ss);
     assert(sslen);
 
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = af;
     hints.ai_socktype = SOCK_DGRAM;
-    if (o.nodns)
-        hints.ai_flags |= AI_NUMERICHOST;
+    hints.ai_flags |= addl_flags;
 
     /* Make the port number a string to give to getaddrinfo. */
     rc = Snprintf(portbuf, sizeof(portbuf), "%hu", port);
@@ -216,6 +215,27 @@ int resolve(char *hostname, unsigned short port,
     return 0;
 }
 
+/* Resolves the given hostname or IP address with getaddrinfo, and stores the
+   first result (if any) in *ss and *sslen. The value of port will be set in the
+   appropriate place in *ss; set to 0 if you don't care. af may be AF_UNSPEC, in
+   which case getaddrinfo may return e.g. both IPv4 and IPv6 results; which one
+   is first depends on the system configuration. Returns 0 on success, or a
+   getaddrinfo return code (suitable for passing to gai_strerror) on failure.
+   *ss and *sslen are always defined when this function returns 0.
+
+   If the global o.nodns is true, then do not resolve any names with DNS. */
+int resolve(const char *hostname, unsigned short port,
+    struct sockaddr_storage *ss, size_t *sslen, int af)
+{
+    int flags;
+
+    flags = 0;
+    if (o.nodns)
+        flags |= AI_NUMERICHOST;
+
+    return resolve_internal(hostname, port, ss, sslen, af, flags);
+}
+
 int fdinfo_close(struct fdinfo *fdn)
 {
 #ifdef HAVE_OPENSSL

ncat/ncat_core.h

@@ -172,10 +172,16 @@ extern struct timeval start_time;
 /* Initializes global options to their default values. */
 void options_init(void);
 
-/* Tries to resolve the given name (or literal IP) into a sockaddr structure.
-   Pass 0 for the port if you don't care. Returns 0 on success, or a getaddrinfo
-   return code on error. */
-int resolve(char *hostname, unsigned short port,
+/* Resolves the given hostname or IP address with getaddrinfo, and stores the
+   first result (if any) in *ss and *sslen. The value of port will be set in the
+   appropriate place in *ss; set to 0 if you don't care. af may be AF_UNSPEC, in
+   which case getaddrinfo may return e.g. both IPv4 and IPv6 results; which one
+   is first depends on the system configuration. Returns 0 on success, or a
+   getaddrinfo return code (suitable for passing to gai_strerror) on failure.
+   *ss and *sslen are always defined when this function returns 0.
+
+   If the global o.nodns is true, then do not resolve any names with DNS. */
+int resolve(const char *hostname, unsigned short port,
             struct sockaddr_storage *ss, size_t *sslen, int af);
 
 int fdinfo_close(struct fdinfo *fdn);

nmap.cc

@@ -996,7 +996,7 @@ void parse_options(int argc, char **argv) {
           /* Try to resolve it */
           struct sockaddr_in decoytemp;
           size_t decoytemplen = sizeof(struct sockaddr_in);
-          if (resolve(p, 0, 0, (sockaddr_storage*)&decoytemp, &decoytemplen, AF_INET) == 0) {
+          if (resolve(p, 0, (sockaddr_storage*)&decoytemp, &decoytemplen, AF_INET) == 0) {
             o.decoys[o.numdecoys] = decoytemp.sin_addr;
             o.numdecoys++;
           } else {
@@ -1338,7 +1338,7 @@ void  apply_delayed_options() {
   size_t sslen;
 
   if (o.spoofsource) {
-    if (resolve(delayed_options.spoofSource, 0, 0, &ss, &sslen, o.af()) != 0)
+    if (resolve(delayed_options.spoofSource, 0, &ss, &sslen, o.af()) != 0)
       fatal("Failed to resolve/decode supposed %s source address %s.", (o.af() == AF_INET) ? "IPv4" : "IPv6", delayed_options.spoofSource);
     o.setSourceSockAddr(&ss, sslen);
   }
@@ -1633,7 +1633,7 @@ int nmap_main(int argc, char *argv[]) {
     size_t sslen;
 
     dst = route_dst_hosts[i].c_str();
-    if (resolve(dst, 0, 0, &ss, &sslen, o.af()) != 0)
+    if (resolve(dst, 0, &ss, &sslen, o.af()) != 0)
       fatal("Can't resolve %s.", dst);
 
     printf("%s\n", inet_ntop_ez(&ss, sslen));
@@ -1936,7 +1936,7 @@ int nmap_main(int argc, char *argv[]) {
             currenths->setSourceSockAddr(&ss, sslen);
           } else {
             if (gethostname(myname, MAXHOSTNAMELEN) ||
-                resolve(myname, 0, 0, &ss, &sslen, o.af()) != 0)
+                resolve(myname, 0, &ss, &sslen, o.af()) != 0)
               fatal("Cannot get hostname!  Try using -S <my_IP_address> or -e <interface to scan through>\n");
 
             o.setSourceSockAddr(&ss, sslen);

nmap_dns.cc

@@ -820,7 +820,7 @@ static void add_dns_server(char *ipaddrs) {
 
   for (hostname = strtok(ipaddrs, " ,"); hostname != NULL; hostname = strtok(NULL, " ,")) {
 
-    if (resolve(hostname, 0, 0, (struct sockaddr_storage *) &addr, &addr_len, PF_UNSPEC) != 0) continue;
+    if (resolve(hostname, 0, (struct sockaddr_storage *) &addr, &addr_len, PF_UNSPEC) != 0) continue;
 
     for(servI = servs.begin(); servI != servs.end(); servI++) {
       tpserv = *servI;

nping/utils_net.cc

@@ -106,7 +106,7 @@ extern NpingOps o;
 int atoIP(const char *hostname, struct in_addr *dst){
   struct sockaddr_in i;
   unsigned int stlen=0;
-  if ( resolve(hostname, 0, 0, (sockaddr_storage*)&i, (size_t *)&stlen , PF_INET) != 0 )
+  if ( resolve(hostname, 0, (sockaddr_storage*)&i, (size_t *)&stlen , PF_INET) != 0 )
     return OP_FAILURE;
   *dst=i.sin_addr;
   return OP_SUCCESS;
@@ -118,7 +118,7 @@ int atoIP(const char *hostname, struct sockaddr_storage *ss, int family){
     return OP_FAILURE;
   if(family!=AF_INET && family!=AF_INET6)
     return OP_FAILURE;
-  if ( resolve(hostname, 0, 0, ss, &stlen , family) != 0 )
+  if ( resolve(hostname, 0, ss, &stlen , family) != 0 )
     return OP_FAILURE;
   return OP_SUCCESS;
 } /* End of atoIP */
@@ -556,7 +556,7 @@ int resolveCached(char *host, struct sockaddr_storage *ss, size_t *sslen, int pf
   misses++;
   outPrint(DBG_4, "resolveCached(): Cache miss %d for %s\n", misses, host);
 
-  if( (result=resolve(host, 0, 0, ss, sslen, pf)) == 0 ){
+  if( (result=resolve(host, 0, ss, sslen, pf)) == 0 ){
 	
 	  /* Increment count */
 	  if( cached_count < MAX_CACHED_HOSTS )