libc: Add gethostbyname(). Untested on initial commit

include/netdb.h

@@ -156,6 +156,27 @@
 #define EAI_SYSTEM      8
 #define EAI_OVERFLOW    9
 
+/* h_errno values that may be returned by gethosbyname(), gethostbyname_r(),
+ * gethostbyaddr(), or gethostbyaddr_r()
+ *
+ *   HOST_NOT_FOUND - No such host is known.
+ *
+ *   NO_DATA - The server recognized the request and the name, but no
+ *     address is available. Another type of request to the name server
+ *     for the domain might return an answer.
+ *
+ *   NO_RECOVERY - An unexpected server failure occurred which cannot be
+ *     recovered.
+ *
+ *   TRY_AGAIN - A temporary and possibly transient error occurred, such as
+ *     a failure of a server to respond.
+ */
+
+#define HOST_NOT_FOUND 1
+#define NO_DATA        2
+#define NO_RECOVERY    3
+#define TRY_AGAIN      4
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -215,7 +236,7 @@ struct addrinfo
 
   FAR struct sockaddr *ai_addr;      /* Socket address of socket.  */
   FAR char            *ai_canonname; /* Canonical name of service location.  */
-  sFAR truct addrinfo *ai_next;      /* Pointer to next in list.  */
+  FAR struct addrinfo *ai_next;      /* Pointer to next in list.  */
 };
 
 /****************************************************************************
@@ -235,46 +256,59 @@ extern "C"
  * macro or an identifier declared with external linkage.
  */
 
-/* To be provided */
+/* REVISIT:  This should at least be per-task? */
+EXTERN int h_errno;
 
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/
 
+#ifdef CONFIG_LIB_NETDB
 #if 0 /* None of these are yet supported */
 
-void              endhostent(void);
+void                 endhostent(void);
-void              endnetent(void);
+void                 endnetent(void);
-void              endprotoent(void);
+void                 endprotoent(void);
-void              endservent(void);
+void                 endservent(void);
-void              freeaddrinfo(FAR struct addrinfo *);
+void                 freeaddrinfo(FAR struct addrinfo *);
-const char       *gai_strerror(int);
+FAR const char      *gai_strerror(int);
-int               getaddrinfo(FAR const char *restrict,
+int                  getaddrinfo(FAR const char *restrict,
-                    FAR const char *restrict,
+                                 FAR const char *restrict,
-                    FAR const struct addrinfo *restrict,
+                                 FAR const struct addrinfo *restrict,
-                    FAR struct addrinfo **restrict);
+                                 FAR struct addrinfo **restrict);
-struct hostent   *gethostbyaddr(FAR const void *, socklen_t, int);
+FAR struct hostent  *gethostbyaddr(FAR const void *, socklen_t, int);
-struct hostent   *gethostbyname(FAR const char *);
+#endif
-struct hostent   *gethostent(void);
+
-int               getnameinfo(FAR const struct sockaddr *restrict, socklen_t,
+FAR struct hostent  *gethostbyname(FAR const char *);
-                    FAR char *restrict, socklen_t, FAR char *restrict,
+
-                    socklen_t, int);
+#if 0 /* None of these are yet supported */
-struct netent    *getnetbyaddr(uint32_t, int);
+FAR struct hostent  *gethostent(void);
-struct netent    *getnetbyname(FAR const char *);
+int                  getnameinfo(FAR const struct sockaddr *restrict, socklen_t,
-struct netent    *getnetent(void);
+                                 FAR char *restrict, socklen_t, FAR char *restrict,
-struct protoent  *getprotobyname(FAR const char *);
+                                 socklen_t, int);
-struct protoent  *getprotobynumber(int);
+FAR struct netent   *getnetbyaddr(uint32_t, int);
-struct protoent  *getprotoent(void);
+FAR struct netent   *getnetbyname(FAR const char *);
-struct servent   *getservbyname(FAR const char *, FAR const char *);
+FAR struct netent   *getnetent(void);
-struct servent   *getservbyport(int, FAR const char *);
+FAR struct protoent *getprotobyname(FAR const char *);
-struct servent   *getservent(void);
+FAR struct protoent *getprotobynumber(int);
-void              sethostent(int);
+FAR struct protoent *getprotoent(void);
-void              setnetent(int);
+FAR struct servent  *getservbyname(FAR const char *, FAR const char *);
-void              setprotoent(int);
+FAR struct servent  *getservbyport(int, FAR const char *);
-void              setservent(int);
+FAR struct servent  *getservent(void);
+void                 sethostent(int);
+void                 setnetent(int);
+void                 setprotoent(int);
+void                 setservent(int);
 
 #endif /* None of these are yet supported */
 
+/* Non-standard interfaces similar to Glibc 2 interfaces */
+
+int gethostbyname_r(FAR const char *name, FAR struct hostent *host,
+                    FAR char *buf, size_t buflen, int *h_errnop);
+
+#endif /* CONFIG_LIB_NETDB */
+
 #undef EXTERN
 #ifdef __cplusplus
 }

libc/Kconfig

@@ -504,6 +504,27 @@ config ARCH_BZERO
 
 endif # ARCH_OPTIMIZED_FUNCTIONS
 
+menuconfig LIB_NETDB
+	bool "Network database support"
+	default n
+	depends on FS_READABLE
+
+if LIB_NETDB
+
+config NETDB_HOSTCONF_PATH
+	string "Path to host configuration file"
+	default "/etc/hosts"
+
+config NETDB_MAX_ALTNAMES
+	int "Max number of alternate host names"
+	default 4
+
+config NETDB_BUFSIZE
+	int "gethostname() buffer size"
+	default 128
+
+endif # LIB_NETDB
+
 comment "Non-standard Library Support"
 
 if BUILD_PROTECTED || BUILD_KERNEL

libc/lib_internal.h

@@ -216,6 +216,13 @@ double lib_expi(size_t n);
 float lib_sqrtapprox(float x);
 #endif
 
+/* Defined in lib_parsehostfile.c */
+
+#ifdef CONFIG_LIB_NETDB
+ssize_t lib_parse_hostfile(FAR FILE *stream, FAR struct hostent *host,
+                           FAR char *buf, size_t buflen);
+#endif
+
 #undef EXTERN
 #if defined(__cplusplus)
 }

libc/net/Make.defs

@@ -44,6 +44,12 @@ ifeq ($(CONFIG_NET_ROUTE),y)
 CSRCS += lib_addroute.c lib_delroute.c
 endif
 
+# netdb support
+
+ifeq ($(CONFIG_LIB_NETDB),y)
+CSRCS += lib_gethostbyname.c lib_gethostbynamer.c lib_parsehostfile.c
+endif
+
 # Add the net directory to the build
 
 DEPPATH += --dep-path net

libc/net/lib_gethostbyname.c

@@ -0,0 +1,106 @@
+/****************************************************************************
+ * net/netdb/lib_gethostbyname.c
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <netdb.h>
+#include <errno.h>
+
+#include "lib_internal.h"
+
+#ifdef CONFIG_LIB_NETDB
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifndef CONFIG_NETDB_BUFSIZE
+#  define CONFIG_NETDB_BUFSIZE 128
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct hostent g_hostent;
+static char g_hostbuffer[CONFIG_NETDB_BUFSIZE];
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: gethostname
+ *
+ * Description:
+ *   The gethostbyname() function returns a structure of type hostent for
+ *   the given host name. Here name is either a hostname, or an IPv4 address
+ *   in standard dot notation (as for inet_addr(3)), or an IPv6 address in
+ *   colon (and possibly dot) notation.
+ *
+ *   If name is an IPv4 or IPv6 address, no lookup is performed and
+ *   gethostbyname_r() simply copies name into the h_name field
+ *   and its struct in_addr equivalent into the h_addr_list[0] field of the
+ *   returned hostent structure.
+ *
+ * Input Parameters:
+ *   name - The name of the host to find.
+ *   
+ * Returned Value:
+ *   Upon successful completion, this function will return a pointer to a
+ *   hostent structure if the requested entry was found, and a null pointer
+ *   if the end of the database was reached or the requested entry was not
+ *   found.
+ *
+ *   Upon unsuccessful completion, gethostbyname() will set h_errno to
+ *   indicate the error
+ *
+ ****************************************************************************/
+
+FAR struct hostent *gethostbyname(FAR const char *name)
+{
+  int ret;
+
+  DEBUGASSERT(name != NULL);
+  ret = gethostbyname_r(name, &g_hostent, g_hostbuffer, CONFIG_NETDB_BUFSIZE,
+                       &h_errno);
+  return ret == 0 ? &g_hostent : NULL;
+}
+
+#endif /* CONFIG_LIB_NETDB */

libc/net/lib_gethostbynamer.c

@@ -0,0 +1,345 @@
+/****************************************************************************
+ * net/netdb/lib_gethostbynamer.c
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <string.h>
+#include <netdb.h>
+#include <errno.h>
+
+#include <arpa/inet.h>
+
+#include "lib_internal.h"
+
+#ifdef CONFIG_LIB_NETDB
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Definitions
+ ****************************************************************************/
+
+/* This is the maximum number of alternate host names supported by this
+ * implementation:
+ */
+
+#ifndef CONFIG_NETDB_MAX_ALTNAMES
+#  define CONFIG_NETDB_MAX_ALTNAMES 4
+#endif
+
+#ifndef CONFIG_NETDB_HOSTCONF_PATH
+#  define CONFIG_NETDB_HOSTCONF_PATH "/etc/hosts"
+#endif
+
+/* This is the layout of the caller provided memory area */
+
+struct hostent_info_s
+{
+  FAR char *hi_addrlist[2];
+  char hi_data[1];
+};
+
+/****************************************************************************
+ * Private functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_numeric_address
+ *
+ * Description:
+ *   Check if the name is a numeric IP address. In this case, simply copy
+ *   name into the h_name field and its struct in_addr equivalent into the
+ *   h_addr_list[0] field of the returned hostent structure.
+ *
+ * Input paramters:
+ *   stream - File stream of the opened hosts file with the file pointer
+ *     positioned at the beginning of the next host entry.
+ *   host - Caller provided location to return the host data.
+ *   buf - Caller provided buffer to hold string data associated with the
+ *     host data.
+ *   buflen - The size of the caller-provided buffer
+ *
+ * Returned Value:
+ *   Zero (0) is returned if the name is an numeric IP address.
+ *
+ ****************************************************************************/
+
+static int lib_numeric_address(FAR const char *name, FAR struct hostent *host,
+                               FAR char *buf, size_t buflen)
+{
+  FAR struct hostent_info_s *info;
+  FAR char *ptr;
+  size_t addrlen;
+  int namelen;
+  int ret;
+
+  /* Verify that we have a buffer big enough to get started (it still may not
+   * be big enough).
+   */
+
+ if (buflen <= sizeof(struct hostent_info_s))
+   {
+     return -ERANGE;
+   }
+
+  info    = (FAR struct hostent_info_s *)buf;
+  ptr     = info->hi_data;
+  buflen -= (sizeof(struct hostent_info_s) - 1);
+
+  memset(host, 0, sizeof(struct hostent));
+  memset(info, 0, sizeof(struct hostent_info_s));
+
+  /* If the address contains a colon, then it might be a numeric IPv6 */
+
+  if (strchr(name, ':') != NULL)
+    {
+      /* Make sure that space remains to hold the IPv6 address */
+
+      addrlen = sizeof(struct in6_addr);
+      if (buflen < addrlen)
+        {
+          return -ERANGE;
+        }
+      
+      ret = inet_pton(AF_INET6, name, ptr);
+      if (ret < 0)
+        {
+          /* Conversion failed.  Must not be a IPv6 address */
+
+          return 1;
+        }
+
+      host->h_addrtype  = AF_INET6;
+    }
+  /* If the address contains a colon, then it might be a numeric IPv6 */
+
+  else if (strchr(name, '.') != NULL)
+    {
+      /* Make sure that space remains to hold the IPv4 address */
+
+      addrlen = sizeof(struct in_addr);
+      if (buflen < addrlen)
+        {
+          return -ERANGE;
+        }
+
+      ret = inet_pton(AF_INET, name, ptr);
+      if (ret < 0)
+        {
+          /* Conversion failed.  Must not be an IPv4 address */
+
+          return 1;
+        }
+
+      host->h_addrtype  = AF_INET;
+    }
+
+  /* No colon?  No period?  Can't be a numeric address */
+
+  else
+    {
+      return 1;
+    }
+
+  info->hi_addrlist[0] = ptr;
+  host->h_addr_list    = info->hi_addrlist;
+  host->h_length       = addrlen;
+
+  ptr                 += addrlen;
+  buflen              -= addrlen;
+
+  /* And copy name */
+
+  namelen = strlen(name);
+  if (addrlen + namelen + 1 > buflen)
+    {
+      return -ERANGE;
+    }
+
+  strncpy(ptr, name, buflen);
+  return 0;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: gethostname_r
+ *
+ * Description:
+ *   The gethostbyname_r() function returns a structure of type hostent for
+ *   the given host name. Here name is either a hostname, or an IPv4 address
+ *   in standard dot notation (as for inet_addr(3)), or an IPv6 address in
+ *   colon (and possibly dot) notation.
+ *
+ *   If name is an IPv4 or IPv6 address, no lookup is performed and
+ *   gethostbyname_r() simply copies name into the h_name field
+ *   and its struct in_addr equivalent into the h_addr_list[0] field of the
+ *   returned hostent structure.
+ *
+ *   gethostname_r() is *not* POSIX but is similar to a Glibc extension and is
+ *   used internally by NuttX to implement the POSIX gethostname().
+ *
+ * Input Parameters:
+ *   name - The name of the host to find.
+ *   host - Caller provided location to return the host data.
+ *   buf - Caller provided buffer to hold string data associated with the
+ *     host data.
+ *   buflen - The size of the caller-provided buffer
+ *   h_errnop - There h_errno value returned in the event of a failure.
+ *   
+ * Returned Value:
+ *   Zero (OK) is returned on success, -1 (ERROR) is returned on a failure
+ *   with the returned h_errno value provided the reason for the failure.
+ *
+ ****************************************************************************/
+
+int gethostbyname_r(FAR const char *name, FAR struct hostent *host,
+                    FAR char *buf, size_t buflen, int *h_errnop)
+{
+  FAR FILE *stream;
+  int herrnocode;
+  int nread;
+
+  DEBUGASSERT(name != NULL && host != NULL && buf != NULL);
+
+  /* Make sure that the h_errno has a non-error code */
+
+  if (h_errnop)
+    {
+      *h_errnop = 0;
+    }
+
+  /* Check for a numeric hostname */
+
+  if (lib_numeric_address(name, host, buf, buflen) == 0)
+    {
+      /* Yes.. we are done */
+
+      return OK;
+    }
+
+  /* Try to find the name in the HOSTALIASES environment variable */
+  /* REVISIT: Not implemented */
+
+  /* Try to get the host address using the DNS name server */
+  /* REVISIT: Not implemented */
+
+  /* Search the hosts file for a match */
+
+  stream = fopen(CONFIG_NETDB_HOSTCONF_PATH, "r");
+  if (stream == NULL)
+    {
+      int errcode = errno;
+
+      ndbg("ERROR:  Failed to open the hosts file %s: %d\n",
+           CONFIG_NETDB_HOSTCONF_PATH, errcode);
+      UNUSED(errcode);
+
+      herrnocode = NO_RECOVERY;
+      goto errorout_with_herrnocode;
+    }
+
+  /* Loop reading entries from the hosts file until a match is found or
+   * until we hit the end-of-file.
+   */
+
+  do
+    {
+      /* Read the next entry from the hosts file */
+
+      nread = lib_parse_hostfile(stream, host, buf, buflen);
+      if (nread < 0)
+        {
+          /* Possible errors:
+           *     ERANGE - Buffer not big enough
+           *     ESPIPE - End of file (or possibly a read error).
+           *     EAGAIN - Error parsing the line (E.g., missing hostname)
+           */
+
+          if (ESPIPE)
+            {
+              nread = 0;
+            }
+          else if (ERANGE)
+            {
+              herrnocode = NO_RECOVERY;
+              goto errorout_with_stream;
+            }
+        }
+      else if (nread > 0)
+        {
+          /* We successfully read the entry */
+
+          nvdbg("Comparing %s to %s\n", name, host->h_name);
+          if (strcmp(name, host->h_name) == 0)
+            {
+               /* We have a match */
+
+               fclose(stream);
+               return OK;
+            }
+        }
+    }
+  while (nread != 0);
+
+  /* We get here when the end of the hosts file is encountered without
+   * finding the hostname.
+   */
+
+  herrnocode = HOST_NOT_FOUND;
+
+errorout_with_stream:
+  fclose(stream);
+
+errorout_with_herrnocode:
+  if (h_errnop)
+    {
+      *h_errnop = herrnocode;
+    }
+
+ return ERROR;
+}
+
+#endif /* CONFIG_LIB_NETDB */

libc/net/lib_parsehostfile.c

@@ -0,0 +1,457 @@
+/****************************************************************************
+ * net/netdb/lib_parsehostile.c
+ *
+ *   Copyright (C) 2015 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+
+#include <arpa/inet.h>
+
+#include "lib_internal.h"
+
+#ifdef CONFIG_LIB_NETDB
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* This is the maximum number of alternate host names supported by this
+ * implementation:
+ */
+
+#ifndef CONFIG_NETDB_MAX_ALTNAMES
+#  define CONFIG_NETDB_MAX_ALTNAMES 4
+#endif
+
+/* Check if character is any kind of white space (except for newline) */
+
+#define lib_isspace(c) \
+  ((c) == ' '  || (c) == '\t' || (c) == '\r' || (c) == '\f' || c== '\v')
+
+/****************************************************************************
+ * Private Type Definitions
+ ****************************************************************************/
+
+/* This is the layout of the caller provided memory area */
+
+struct hostent_info_s
+{
+  FAR char *hi_aliases[CONFIG_NETDB_MAX_ALTNAMES + 1];
+  FAR char *hi_addrlist[2];
+  char hi_data[1];
+};
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/* When the <netdb.h> header is included, h_errno shall be available as a
+ * modifiable lvalue of type int. It is unspecified whether h_errno is a
+ * macro or an identifier declared with external linkage.
+ */
+
+/* REVISIT:  This should at least be per-task? */
+int h_errno;
+
+/****************************************************************************
+ * Private functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_skipspaces
+ ****************************************************************************/
+
+static int lib_skipspaces(FAR FILE *stream, FAR size_t *nread)
+{
+  int ch;
+
+  /* Skip over most white space (but not newline) */
+
+  do
+    {
+      ch = fgetc(stream);
+      if (ch != EOF)
+        {
+          (*nread)++;
+        }
+    }
+  while (lib_isspace(ch));
+
+  return ch;
+}
+
+/****************************************************************************
+ * Name: lib_skipline
+ ****************************************************************************/
+
+static int lib_skipline(FAR FILE *stream, FAR size_t *nread)
+{
+  int ch;
+
+  /* Skip over all characters until we encounter a newline or end-of-file */
+
+  do
+    {
+      ch = fgetc(stream);
+      if (ch != EOF)
+        {
+          (*nread)++;
+        }
+    }
+  while (ch != EOF && ch != '\n');
+
+  return ch;
+}
+
+/****************************************************************************
+ * Name: lib_copystring
+ *
+ * Returned Value:
+ *  Number of bytes written to the buffer on success.  0 if the end of
+ *  file is encountered (or a read error occurs).  A negated errno value on
+ *  any failure:
+ *
+ *    -ERANGE - Insufficient buffer space
+ *
+ ****************************************************************************/
+
+static ssize_t lib_copystring(FAR FILE *stream, FAR char *ptr, FAR size_t *nread,
+                              size_t buflen, FAR int *terminator)
+{
+  size_t nwritten = 0;
+  int ch;
+
+  /* Copy the string from the file until any whitepace delimiter is
+   * encountered
+   */
+
+  for(;;)
+    {
+      /* Read the next character from the file */
+
+      ch = fgetc(stream);
+      if (ch != EOF)
+        {
+          (*nread)++;
+        }
+
+      /* Check for whitepace (including \n') or EOF terminating the string */
+
+      if (isspace(ch) || ch == EOF)
+        {
+          /* Remeber what terminated the string */
+
+          *terminator = ch;
+
+          /* Add NUL termination */
+
+          *ptr++ = '\0';
+
+          /* Return EOF if nothing has written */
+          return nwritten == 0 ? 0 : nwritten + 1;
+        }
+
+      /* Write the next string to the buffer */
+
+      *ptr++ = ch;
+      nwritten++;
+
+      /* There there space to buffer one more character? */
+
+      if (nwritten >= buflen)
+        {
+          return -ERANGE;
+        }
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: lib_parse_hostfile
+ *
+ * Description:
+ *   Parse the next line from the hosts file.
+ *
+ * Input Parameters:
+ *   stream - File stream of the opened hosts file with the file pointer
+ *     positioned at the beginning of the next host entry.
+ *   host - Caller provided location to return the host data.
+ *   buf - Caller provided buffer to hold string data associated with the
+ *     host data.
+ *   buflen - The size of the caller-provided buffer
+ *
+ * Returned Value:
+ *   The non-zero number of bytes read from the hosts file is returned if
+ *   the host entry was successfully read.  Zero is returned if the end
+ *   of the host file has been reached.  A negated errno value is return
+ *   in the event a failure:
+ *
+ *     ERANGE - Buffer not big enough
+ *     ESPIPE - End of file (or possibly a read error).
+ *     EAGAIN - Error parsing the line (E.g., missing hostname)
+ *
+ ****************************************************************************/
+
+ssize_t lib_parse_hostfile(FAR FILE *stream, FAR struct hostent *host,
+                           FAR char *buf, size_t buflen)
+{
+  FAR struct hostent_info_s *info;
+  FAR char addrstring[48];
+  FAR char *ptr;
+  FAR char *start;
+  size_t addrlen;
+  size_t nread = 0;
+  ssize_t nwritten;
+  int ret;
+  int ch;
+  int i;
+
+  /* Verify that we have a buffer big enough to get started (it still may not
+   * be big enough).
+   */
+
+ if (buflen <= sizeof(struct hostent_info_s))
+   {
+     return -ERANGE;
+   }
+
+  info    = (FAR struct hostent_info_s *)buf;
+  ptr     = info->hi_data;
+  buflen -= (sizeof(struct hostent_info_s) - 1);
+
+  memset(host, 0, sizeof(struct hostent));
+  memset(info, 0, sizeof(struct hostent_info_s));
+
+  /* Skip over any leading spaces */
+
+  do
+    {
+      ch = lib_skipspaces(stream, &nread);
+      if (ch == EOF)
+        {
+          return -EPIPE;
+        }
+
+      /* Skip comment lines beginning with '#' */
+
+      if (ch == '#')
+        {
+           /* Skip to the end of line. */
+
+          ch = lib_skipline(stream, &nread);
+          if (ch == EOF)
+            {
+              return -EPIPE;
+            }
+        }
+    }
+  while (ch == '\n');
+
+  /* Parse the IP address */
+
+  addrstring[0] = ch;
+
+  nwritten = lib_copystring(stream, addrstring, &nread, 48, &ch);
+  if (nwritten <= 0)
+    {
+      return nwritten;
+    }
+
+  if (!lib_isspace(ch))
+    {
+      /* The string was terminated with a newline of EOF */
+
+      return -EAGAIN;
+    }
+
+  /* If the address contains a colon, say it is IPv6 */
+
+  if (strchr(addrstring, ':') != NULL)
+    {
+      /* Make sure that space remains to hold the IPv6 address */
+
+      addrlen = sizeof(struct in6_addr);
+      if (buflen < addrlen)
+        {
+          return -ERANGE;
+        }
+      
+      ret = inet_pton(AF_INET6, addrstring, ptr);
+      if (ret < 0)
+        {
+          /* Conversion failed.  Entry is corrupted */
+
+          (void)lib_skipline(stream, &nread);
+          return -EAGAIN;
+        }
+
+      host->h_addrtype  = AF_INET6;
+    }
+  else
+    {
+      /* Make sure that space remains to hold the IPv4 address */
+
+      addrlen = sizeof(struct in_addr);
+      if (buflen < addrlen)
+        {
+          return -ERANGE;
+        }
+
+      ret = inet_pton(AF_INET, addrstring, ptr);
+      if (ret < 0)
+        {
+          /* Conversion failed.  Entry is corrupted */
+
+          (void)lib_skipline(stream, &nread);
+          return -EAGAIN;
+        }
+
+      host->h_addrtype  = AF_INET;
+    }
+
+  info->hi_addrlist[0] = ptr;
+  host->h_addr_list    = info->hi_addrlist;
+  host->h_length       = addrlen;
+
+  ptr                 += addrlen;
+  buflen              -= addrlen;
+
+  /* Skip over any additional whitespace */
+
+  ch = lib_skipspaces(stream, &nread);
+  if (ch == EOF)
+    {
+      return -EPIPE;
+    }
+  else if (ch == '\n')
+    {
+      return -EAGAIN;
+    }
+
+  /* Parse the host name */
+
+  start = ptr;
+  *ptr++ = ch;
+  buflen--;
+
+  nwritten = lib_copystring(stream, ptr, &nread, buflen, &ch);
+  if (nwritten <= 0)
+    {
+      return nwritten;
+    }
+
+  host->h_name = start;
+
+  if (!lib_isspace(ch))
+    {
+      /* The string was terminated with a newline or EOF */
+
+      return nread;
+    }
+
+  ptr += nwritten;
+  buflen -= nwritten;
+
+  /* Parse any host name aliases */
+
+  for (i = 0; i < CONFIG_NETDB_MAX_ALTNAMES; i++)
+    {
+      /* Skip over any leading whitespace */
+
+      ch = lib_skipspaces(stream, &nread);
+      if (ch == EOF || ch == '\n')
+        {
+          /* No further aliases on the line */
+
+          return nread;
+        }
+
+      /* Parse the next alias */
+
+      start = ptr;
+      *ptr++ = ch;
+      buflen--;
+
+      nwritten = lib_copystring(stream, ptr, &nread, buflen, &ch);
+      if (nwritten < 0)
+        {
+          return nwritten;
+        }
+      else if (nwritten == 0)
+        {
+          return nread;
+        }
+
+       /* Save the pointer to the beginning of the next alias */
+
+       info->hi_aliases[i] = start;
+       if (host->h_aliases == NULL)
+         {
+           host->h_aliases = info->hi_aliases;
+         }
+
+      if (!lib_isspace(ch))
+        {
+          /* The string was terminated with a newline of EOF */
+
+          return nread;
+        }
+
+      ptr += nwritten;
+      buflen -= nwritten;
+    }
+
+  /* We get here only if there are more than CONFIG_NETDB_MAX_ALTNAMES
+   * aliases on the line.  Skip to the endof the line, ignoring any
+   * additional aliases.
+   */
+
+  (void)lib_skipline(stream, &nread);
+  return nread;
+}
+
+#endif /* CONFIG_LIB_NETDB */