Added ares_getnameinfo which mimics the getnameinfo API

1 files changed, 322 insertions, 0 deletions

diff --git a/ares_getnameinfo.c b/ares_getnameinfo.c
new file mode 100644
index 0000000..955207a
--- /dev/null
+++ b/ares_getnameinfo.c
@@ -0,0 +1,322 @@
+/* Copyright 2005 by Dominick Meglio
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is"
+ * without express or implied warranty.
+ */
+#include "setup.h"
+#include <sys/types.h>
+
+#if defined(WIN32) && !defined(WATT32)
+#include "nameser.h"
+#else
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <arpa/nameser.h>
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+#include <arpa/nameser_compat.h>
+#endif
+#endif
+
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "ares.h"
+#include "ares_private.h"
+#include "ares_ipv6.h"
+#include "inet_ntop.h"
+
+#ifdef WATT32
+#undef WIN32
+#endif
+
+struct nameinfo_query {
+  ares_nameinfo_callback callback;
+  void *arg;
+  union {
+    struct sockaddr_in addr4;
+    struct sockaddr_in6 addr6;
+  } addr;
+  int family;
+  int flags;
+};
+
+#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
+#define IPBUFSIZ 40+IF_NAMESIZE
+#else
+#define IPBUFSIZ 40
+#endif
+
+static void nameinfo_callback(void *arg, int status, struct hostent *host);
+static char *lookup_service(unsigned short port, int flags, char *buf);
+static char *append_scopeid(struct sockaddr_in6 *addr6, unsigned int scopeid, char *buf);
+static char *ares_striendstr(const char *s1, const char *s2);
+
+void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa, socklen_t salen,
+                      int flags, ares_nameinfo_callback callback, void *arg)
+{
+  struct sockaddr_in *addr;
+  struct sockaddr_in6 *addr6;
+  struct nameinfo_query *niquery;
+
+  /* Verify the buffer size */
+  if (salen == sizeof(struct sockaddr_in))
+    addr = (struct sockaddr_in *)sa;
+  else if (salen == sizeof(struct sockaddr_in6))
+    addr6 = (struct sockaddr_in6 *)sa;
+  else
+    {
+      callback(arg, ARES_ENOTIMP, NULL, NULL);
+      return;
+    }
+
+  /* If neither, assume they want a host */
+  if (!(flags & ARES_NI_LOOKUPSERVICE) && !(flags & ARES_NI_LOOKUPHOST))
+    flags |= ARES_NI_LOOKUPHOST;
+
+  /* All they want is a service, no need for DNS */
+  if ((flags & ARES_NI_LOOKUPSERVICE) && !(flags & ARES_NI_LOOKUPHOST))
+    {
+      char buf[33], *service;
+      unsigned int port = 0;
+
+      if (salen == sizeof(struct sockaddr_in))
+        port = addr->sin_port;
+      else
+        port = addr6->sin6_port;
+      service = lookup_service(port, flags, buf);
+      callback(arg, ARES_SUCCESS, NULL, service);
+      return;
+    }
+
+  /* They want a host lookup */
+  if ((flags & ARES_NI_LOOKUPHOST))
+    {
+     /* A numeric host can be handled without DNS */
+     if ((flags & ARES_NI_NUMERICHOST))
+      {
+        unsigned int port = 0;
+        char ipbuf[IPBUFSIZ];
+        char srvbuf[32];
+        char *service = NULL;
+        ipbuf[0] = 0;
+
+        /* Specifying not to lookup a host, but then saying a host 
+         * is required has to be illegal.
+         */
+        if (flags & ARES_NI_NAMEREQD)
+          {
+            callback(arg, ARES_EBADFLAGS, NULL, NULL);
+            return;
+          }
+        if (salen == sizeof(struct sockaddr_in6))
+          {
+            ares_inet_ntop(AF_INET6, &addr6->sin6_addr, ipbuf, IPBUFSIZ);
+            port = addr6->sin6_port;
+            /* If the system supports scope IDs, use it */
+#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
+            append_scopeid(addr6, flags, ipbuf);
+#endif
+          }
+        else
+          {
+            ares_inet_ntop(AF_INET, &addr->sin_addr, ipbuf, IPBUFSIZ);
+            port = addr->sin_port;
+          }
+        /* They also want a service */
+        if (flags & ARES_NI_LOOKUPSERVICE)
+          service = lookup_service(port, flags, srvbuf);
+        callback(arg, ARES_SUCCESS, ipbuf, service);
+        return;
+      }
+    /* This is where a DNS lookup becomes necessary */
+    else
+      {
+        niquery = malloc(sizeof(struct nameinfo_query));
+        if (!niquery)
+          {
+            callback(arg, ARES_ENOMEM, NULL, NULL);
+            return;
+          }
+        niquery->callback = callback;
+        niquery->arg = arg;
+        niquery->flags = flags;
+        if (sa->sa_family == AF_INET) 
+          {
+            niquery->family = AF_INET;
+            memcpy(&niquery->addr.addr4, addr, sizeof(addr));
+            ares_gethostbyaddr(channel, &addr->sin_addr, sizeof(struct in_addr), AF_INET, 
+                               nameinfo_callback, niquery);
+          }
+        else
+          {
+            niquery->family = AF_INET6;
+            memcpy(&niquery->addr.addr6, addr6, sizeof(addr6));
+            ares_gethostbyaddr(channel, &addr6->sin6_addr, sizeof(struct in6_addr), AF_INET6, 
+                               nameinfo_callback, niquery);
+          }
+      }
+    }
+}
+
+static void nameinfo_callback(void *arg, int status, struct hostent *host)
+{
+  struct nameinfo_query *niquery = (struct nameinfo_query *) arg;
+  char srvbuf[33];
+  char *service = NULL;
+
+
+  if (status == ARES_SUCCESS)
+    {
+      /* They want a service too */
+      if (niquery->flags & ARES_NI_LOOKUPSERVICE)
+        {
+          if (niquery->family == AF_INET)
+            service = lookup_service(niquery->addr.addr4.sin_port, niquery->flags, srvbuf);
+          else
+            service = lookup_service(niquery->addr.addr6.sin6_port, niquery->flags, srvbuf);
+        }
+      /* NOFQDN means we have to strip off the domain name portion.
+         We do this by determining our own domain name, then searching the string
+         for this domain name and removing it.
+       */
+      if (niquery->flags & ARES_NI_NOFQDN)
+        {
+           char buf[255];
+           char *domain;
+           gethostname(buf, 255);
+           if ((domain = strchr(buf, '.')))
+             {
+               char *end = ares_striendstr(host->h_name, domain);
+               if (end)
+                 *end = 0;
+             }        
+        }
+      callback(niquery->arg, ARES_SUCCESS, host->h_name, service);
+      return;
+    }
+  /* We couldn't find the host, but it's OK, we can use the IP */
+  else if (status == ARES_ENOTFOUND && !(niquery->flags & ARES_NI_NAMEREQD))
+    {
+      char ipbuf[IPBUFSIZ];
+      if (niquery->family == AF_INET)
+        ares_inet_ntop(AF_INET, &niquery->addr.addr4.sin_addr, ipbuf, IPBUFSIZ);
+      else
+        {
+          ares_inet_ntop(AF_INET6, &niquery->addr.addr6.sin6_addr, ipbuf, IPBUFSIZ);
+#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
+          append_scopeid(&niquery->addr.addr6, niquery->flags, ipbuf);
+#endif
+        }
+      /* They want a service too */
+      if (niquery->flags & ARES_NI_LOOKUPSERVICE)
+        {
+          if (niquery->family == AF_INET)
+            service = lookup_service(niquery->addr.addr4.sin_port, niquery->flags, srvbuf);
+          else
+            service = lookup_service(niquery->addr.addr6.sin6_port, niquery->flags, srvbuf);
+        }
+      callback(niquery->arg, ARES_SUCCESS, ipbuf, service);
+      return;
+    }
+  callback(niquery->arg, status, NULL, NULL);
+  free(niquery);
+}
+
+static char *lookup_service(unsigned short port, int flags, char *buf)
+{
+  if (port)
+    {
+      /* Just return the port as a string */
+      if (flags & ARES_NI_NUMERICSERV)
+        sprintf(buf, "%u", ntohs(port));
+      else
+        {
+          struct servent *se;
+          char *proto;
+ 
+          if (flags & ARES_NI_UDP)
+            proto = "udp";
+          else if (flags & ARES_NI_SCTP)
+            proto = "sctp";
+          else if (flags & ARES_NI_DCCP)
+            proto = "dccp";
+          else
+            proto = "tcp";
+          se = getservbyport(port, proto);
+          if (se && se->s_name)
+            strcpy(buf, se->s_name);
+          else
+            sprintf(buf, "%u", ntohs(port));
+        }
+      return buf;
+    }
+  return NULL;
+}
+
+#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
+static char *append_scopeid(struct sockaddr_in6 *addr6, unsigned int flags, char *buf)
+{
+  char tmpbuf[IF_NAMESIZE + 1];
+
+  tmpbuf[0] = '%';
+#ifdef HAVE_IF_INDEXTONAME
+  if ((flags & ARES_NI_NUMERICSCOPE) || (!IN6_IS_ADDR_LINKLOCAL(&addr6->sin6_addr)
+      && !IN6_IS_ADDR_MC_LINKLOCAL(&addr6->sin6_addr)))
+    {
+       sprintf(&tmpbuf[1], "%u", addr6->sin6_scope_id);
+    }
+  else
+    {
+      if (if_indextoname(addr6->sin6_scope_id, &tmpbuf[1]) == NULL)
+        sprintf(&tmpbuf[1], "%u", addr6->sin6_scope_id);
+    }
+#else
+  sprintf(&tmpbuf[1], "%u", addr6->sin6_scope_id);
+#endif
+  strcat(buf, tmpbuf);
+  return buf;
+}
+#endif
+
+/* Determines if s1 ends with the string in s2 (case-insensitive) */
+static char *ares_striendstr(const char *s1, const char *s2)
+{
+  const char *c1, *c2, *c1_begin;
+  size_t s1_len = strlen(s1), s2_len = strlen(s2);
+
+  /* If the substr is longer than the full str, it can't match */
+  if (s2_len > s1_len)
+    return NULL;
+
+  /* Jump to the end of s1 minus the length of s2 */
+  c1 = (const char *)c1_begin = s1+s1_len-s2_len;
+  c2 = s2;
+  while (c2 < s2+s2_len)
+    {
+      if (tolower(*c1) != tolower(*c2))
+        return NULL;
+      else
+        {
+          c1++;
+          c2++;
+        }
+    }
+  if (c2 == c1 == NULL)
+    return c1_begin;
+  return NULL;
+}