libc/rexec/rexec_af: support remote execution

Signed-off-by: Jiuzhu Dong <dongjiuzhu1@xiaomi.com>

include/netdb.h

@@ -277,6 +277,12 @@ EXTERN int h_errno;
  * Public Function Prototypes
  ****************************************************************************/
 
+int rexec(FAR char **ahost, int inport, FAR const char *user,
+          FAR const char *passwd, FAR const char *cmd, FAR int *fd2p);
+int rexec_af(FAR char **ahost, int inport, FAR const char *user,
+             FAR const char *passwd, FAR const char *cmd, FAR int *fd2p,
+             sa_family_t af);
+
 #ifdef CONFIG_LIBC_NETDB
 #if 0 /* None of these are yet supported */
 

libs/libc/netdb/Make.defs

@@ -29,7 +29,7 @@ CSRCS += lib_gethostbyaddr.c lib_gethostbyaddrr.c
 CSRCS += lib_getservbyname.c lib_getservbynamer.c
 CSRCS += lib_getservbyport.c lib_getservbyportr.c
 CSRCS += lib_gaistrerror.c lib_freeaddrinfo.c lib_getaddrinfo.c
-CSRCS += lib_getnameinfo.c
+CSRCS += lib_getnameinfo.c lib_rexec.c
 
 # Add host file support
 

libs/libc/netdb/lib_rexec.c

@@ -0,0 +1,212 @@
+/****************************************************************************
+ * libs/libc/netdb/lib_rexec.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <netinet/in.h>
+
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: rexec_af
+ *
+ * Description:
+ *   The rexec() function works over IPv4 (AF_INET). By contrast,
+ *   the rexec_af() function provides an extra argument, af, that allows
+ *   the caller to select the protocol. This argument can be specified
+ *   as AF_INET, AF_INET6, or AF_UNSPEC (to allow the implementation to
+ *   select the protocol).
+ *
+ * Input Parameters:
+ *
+ * Returned Value:
+ *   OK on success; -1 on failure with the errno variable set appropriately.
+ *
+ ****************************************************************************/
+
+int rexec_af(FAR char **ahost, int inport, FAR const char *user,
+             FAR const char *passwd, FAR const char *cmd,
+             FAR int *fd2p, sa_family_t af)
+{
+  FAR struct addrinfo *res;
+  struct addrinfo hints;
+  char port_str[12];
+  int sock;
+  int ret;
+
+  if (!cmd || !ahost)
+    {
+      set_errno(EINVAL);
+      return -1;
+    }
+
+  snprintf(port_str, sizeof(port_str), "%d", ntohs(inport));
+
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = af;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_flags = AI_CANONNAME;
+
+  ret = getaddrinfo(*ahost, port_str, &hints, &res);
+  if (ret < 0)
+    {
+      return -1;
+    }
+
+  if (res->ai_canonname)
+    {
+      *ahost = strdup(res->ai_canonname);
+      if (*ahost == NULL)
+        {
+          set_errno(ENOMEM);
+          goto addr_out;
+        }
+    }
+  else
+    {
+      *ahost = NULL;
+      set_errno(ENOENT);
+      goto addr_out;
+    }
+
+  sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
+  if (sock < 0)
+    {
+      goto sock_out;
+    }
+
+  if (connect(sock, res->ai_addr, res->ai_addrlen) < 0)
+    {
+      goto conn_out;
+    }
+
+  /* ignore second connection(fd2p always is NULL) */
+
+  write(sock, "", 1);
+
+  /* Send username */
+
+  if (user)
+    {
+      ret = write(sock, user, strlen(user) + 1);
+    }
+  else
+    {
+      ret = write(sock, "", 1);
+    }
+
+  if (ret < 0)
+    {
+      goto conn_out;
+    }
+
+  /* Send passwd */
+
+  if (passwd)
+    {
+      ret = write(sock, passwd, strlen(passwd) + 1);
+    }
+  else
+    {
+      ret = write(sock, "", 1);
+    }
+
+  if (ret < 0)
+    {
+      goto conn_out;
+    }
+
+  /* Send command */
+
+  ret = write(sock, cmd, strlen(cmd) + 1);
+  if (ret < 0)
+    {
+      goto conn_out;
+    }
+
+  freeaddrinfo(res);
+  return sock;
+
+conn_out:
+  close(sock);
+sock_out:
+  free(ahost);
+addr_out:
+  freeaddrinfo(res);
+  return -1;
+}
+
+/****************************************************************************
+ * Name: rexec
+ *
+ * Description:
+ *   The rexec() function looks up the host *ahost using gethostbyname(),
+ *   returning -1 if the host does not exist. Otherwise, *ahost is set to
+ *   standard name of the host. If a username and password are both
+ *   specified, then these are used to authenticate to the foreign host;
+ *   otherwise the environment and then the .netrc file in user's home
+ *   direcotry are searched for appropiate information. If all the fails,
+ *   the user is prompted for the information.
+ *
+ *   The port inport specifies which well-known DARPA Internet port to
+ *   use for the  connection; the call getservbyname("exec", "tcp") will
+ *   return a pointer to a structure that contains the necessary port.
+ *   The protocol for connection is described in  detail in rexecd(8).
+ *
+ *   If the connection succeeds, a socket in the Internet domain of type
+ *   SOCK_STREAM is returned to the caller, and given to the remote
+ *   command as stdin and stdout. If fd2p is nonzero, then an auxiliary
+ *   channel to a control process will be setup, and a file descriptor for
+ *   it will be placed in *fd2p. The control process will return diagnostic
+ *   output from the command on this channel, and will also
+ *   accept bytes on this channel as being UNIX signal numbers, to be
+ *   forwarded to the process group of the command. The diagnostic
+ *   information returned does not include remote authorization failure,
+ *   as the secondary connection is set up after authorization has been
+ *   verified. If fd2p is 0, then the stderr (unit2 of the remote command)
+ *   will be made the same as the stdout and no provision is made for
+ *   sending arbitrary signals to the remote process, although you may
+ *   be able to get its  attention by using out-of-band data.
+ *
+ *   The rexec() function works over IPv4 (AF_INET).
+ *
+ * Input Parameters:
+ *
+ * Returned Value:
+ *   OK on success; -1 on failure with the errno variable set appropriately.
+ *
+ ****************************************************************************/
+
+int rexec(FAR char **ahost, int inport, FAR const char *user,
+          FAR const char *passwd, FAR const char *cmd, FAR int *fd2p)
+{
+  return rexec_af(ahost, inport, user, passwd, cmd, fd2p, AF_INET);
+}