The following sections provide sample code describing how sockets work.
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Although there is a great deal of similarity between the two APIs, the parameters of the two sets of functions differ slightly. The purpose of the following sections is o give developers a first look at Micrium’s functions by providing concrete examples of how to use the API.
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| BSD | Net Sock | Net App | Description |
|---|---|---|---|
| socket() | NetSock_Open() | NetApp_SockOpen() | Create a datagram (i.e., UDP) or stream (i.e., TCP) type socket. |
| bind() | NetSock_Bind() | NetApp_SockBind() | Assign network addresses to sockets. |
| connect() | NetSock_Conn() | NetApp_SockConn() | Connect a local socket to a remote socket address. |
| listen() | NetSock_Listen() | NetApp_SockListen() | Set a socket to accept incoming connections. |
| accept() | NetSock_Accept() | NetApp_SockAccept() | Wait for new socket connections on a listening server socket. |
| recv() / recvfrom() | NetSock_RxData() / NetSock_RxDataFrom() | NetApp_SockRx() | Copy up to a specified number of bytes received from a remote socket into an application memory buffer. |
| send() / sendto() | NetSock_TxData() / NetSock_TxDataTo() | NetApp_SockTx() | Copy bytes from an application memory buffer into a socket to send to a remote socket. |
| close() | NetSock_Close() | NetApp_SockClose() | Terminate communication and free a socket. |
| select() | NetSock_Sel() | N/A | Check if any sockets are ready for available read or write operations or error conditions. |
| N/A | NetSock_SelAbort() | N/A | Abort a select (i.e. unblock task(s) waiting on socket(s) using the select) |
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| BSD | µC/TCPIP Functions | Description |
|---|---|---|
| htonl | Convert 32-bit integer values from network-order to CPU host-order. | |
| htons() | NET_UTIL_HOST_TO_NET_16() | Convert 16-bit integer values from network-order to CPU host-order. |
| ntohl() | NET_UTIL_NET_TO_HOST_32() | Convert 32-bit integer values from network-order to CPU host-order. |
| ntohs() | NET_UTIL_NET_TO_HOST_16() | Convert 16-bit integer values from network-order to CPU host-order. |
| inet_addr() | NetASCII_Str_to_IPv4() | Convert a string of an IPv4 address in dotted-decimal notation to an IPv4 address in host-order. |
| inet_aton() | NetASCII_Str_to_IPv4() | Convert an IPv4 address in ASCII dotted-decimal notation to a network protocol IPv4 address in network-order. |
| inet_ntoa() | NetASCII_IPv4_to_Str() | Convert an IPv4 address in host-order into an IPv4 dotted-decimal notation ASCII string. |
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It is possible to configure many options on a socket, with the followings function you could configure majority of socket's option but some other option can be accessed using some specific API, please refer to Socket Options section.
| BSD | Net Sock | Description |
|---|---|---|
| getsockopt() | NetSock_OptGet() | Get a specific option value on a specific socket. |
| setsockopt() | NetSock_OptSet() | Set a specific option value on a specific socket. |
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The following functions should be used when select() is used. It helps to configure and read descriptors to a select() calls.
| BSD | Net Sock | Description |
|---|---|---|
| FD_CLR() | NET_SOCK_DESC_CLR() | Remove a socket file descriptor ID as a member of a file descriptor set. |
| FD_ISSET() | NET_SOCK_DESC_IS_SET() | Check if a socket file descriptor ID is a member of a file descriptor set. |
| FD_SET() | NET_SOCK_DESC_SET() | Add a socket file descriptor ID as a member of a file descriptor set. |
| FD_ZERO() | NET_SOCK_DESC_INIT() | Initialize/zero-clear a file descriptor set. |
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Here is a list of other APIs functions that can help in certain condition:
| Function | Description |
|---|---|
| NetApp_SetSockAddr() | Setup a socket address from an IPv4 or an IPv6 address. |
| NetApp_ClientStreamOpen() | Open a stream socket for a client using an IPv4 or IPv6 address. |
| NetApp_ClientStreamOpenByHostname() | Open a stream socket for a client using a hostname (resolve the hostname using µC/DNSc + Autoselect remote address) |
| NetApp_TimeDly_ms() | Delay for specified time, in milliseconds. |
| NetSock_GetConnTransportID() | Gets a socket’s transport layer connection handle ID (e.g., TCP connection ID) if available. |
| NetSock_IsConn() | Check if a socket is connected to a remote socket. |
| NetSock_PoolStatResetMaxUsed() | Reset Network Sockets’ statistics pool’s maximum number of entries used. |
Socket Error Codes
When socket functions return error codes, the error codes should be inspected to determine if the error is a temporary, non-fault condition (such as no data to receive) or fatal (such as the socket has been closed).
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NET_SOCK_ERR_INVALID_FAMILY
NET_SOCK_ERR_INVALID_PROTOCOL
NET_SOCK_ERR_INVALID_TYPE
NET_SOCK_ERR_INVALID_STATE
NET_SOCK_ERR_FAULT
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Whenever any of the following fatal error codes are returned by any µC/TCP-IP socket function, that socket must not be accessed by any other socket functions but must also not be closed()’d:
NET_SOCK_ERR_NOT_USED
Socket Error Code List
All the possible error codes returned by the µC/TCP-IP stack are defined in net_err.h. Please refer to net_err.h for more details on any specific error code.