This change adds support for semi-standard IPPROTO_ICMP AF_INET datagram sockets. This replaces the old ad hoc, nonstandard way of implementing ping with a more standard, socket interface.

Squashed commit of the following:

    net/icmp:  Finishes off icmp_recvfrom().
    net/icmp:  Add readahead support for IPPROTO_ICMP sockets.
    net/icmp:  Add poll() support for IPPROTO_ICMP sockets.
    net/icmp:  Add a connection structure for IPPROTO_ICMP sockets.
    net/icmp:  Implements sendto for the IPPROTO_ICMP socket.
    net/icmp:  Move icmp_sendto() and icmp_recvfrom() to separate files.  They are likely to be complex (when they are implemented).
    net/icmp:  Hook IPPROTO_ICMP sockets into network.  Fix some naming collisions.  Still missing basic ICMP send/receive logic.
    configs: apps/system/ping current need poll() enabled.
    configs: All defconfig files that use to enable low-level support must now enabled CONFIG_SYSTEM_PING.
    net/icmp:  Adds basic build framework to support IPPROTO_ICMP sockets.

include/nuttx/net/icmp.h

@@ -92,8 +92,8 @@
 
 /* Header sizes */
 
-#define ICMP_HDRLEN    4                           /* Size of ICMP header */
-#define IPICMP_HDRLEN  (ICMP_HDRLEN + IPv4_HDRLEN) /* Size of IP + ICMP header */
+#define ICMP_HDRLEN    8                           /* Size of ICMP header */
+#define IPICMP_HDRLEN  (ICMP_HDRLEN + IPv4_HDRLEN) /* Size of IPv4 + ICMP header */
 
 /****************************************************************************
  * Public Type Definitions
@@ -182,36 +182,6 @@ extern "C"
  * Public Function Prototypes
  ****************************************************************************/
 
-/****************************************************************************
- * Name: imcp_ping
- *
- * Description:
- *   Send a ECHO request and wait for the ECHO response
- *
- * Parameters:
- *   addr  - The IP address of the peer to send the ICMP ECHO request to
- *           in network order.
- *   id    - The ID to use in the ICMP ECHO request.  This number should be
- *           unique; only ECHO responses with this matching ID will be
- *           processed (host order)
- *   seqno - The sequence number used in the ICMP ECHO request.  NOT used
- *           to match responses (host order)
- *   dsecs - Wait up to this many deci-seconds for the ECHO response to be
- *           returned (host order).
- *
- * Return:
- *   seqno of received ICMP ECHO with matching ID (may be different
- *   from the seqno argument (may be a delayed response from an earlier
- *   ping with the same ID). Or a negated errno on any failure.
- *
- * Assumptions:
- *   Called from the user level with interrupts enabled.
- *
- ****************************************************************************/
-
-int icmp_ping(in_addr_t addr, uint16_t id, uint16_t seqno, uint16_t datalen,
-              int dsecs);
-
 #undef EXTERN
 #ifdef __cplusplus
 }

include/nuttx/net/net.h

@@ -79,7 +79,7 @@
 #  define _NX_GETERRNO(r)           (-(r))
 #  define _NX_GETERRVAL(r)          (r)
 #else
-#  define _NX_SEND(s,b,l,f)         send(s,b,l,f) 
+#  define _NX_SEND(s,b,l,f)         send(s,b,l,f)
 #  define _NX_RECV(s,b,l,f)         recv(s,b,l,f)
 #  define _NX_RECVFROM(s,b,l,f,a,n) recvfrom(s,b,l,f,a,n)
 #  define _NX_GETERRNO(r)           errno

include/nuttx/net/netconfig.h

@@ -226,7 +226,7 @@
 /* ICMP configuration options */
 
 #ifndef CONFIG_NET_ICMP
-#  undef CONFIG_NET_ICMP_PING
+#  undef CONFIG_NET_ICMP_SOCKET
 #endif
 
 /* UDP configuration options */