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udp_recvfrom

---

int udp_recvfrom( udp_Socket *s, char *buffer, int len,
longword *remip, word *remport );

Description

Receive a single UDP datagram on a UDP socket. remip and remport should be pointers to the locations where the remote IP address and remote port from which the datagram originated are placed. If the buffer is not large enough for the datagram, then the datagram will be truncated, with the remainder being discarded.

If and only if the UDP_MODE_ICMP or UDP_MODE_DICMP modes are set for this socket, then a return code of -3 indicates that an ICMP error message is being returned in the buffer instead of a normal datagram. In this case, buffer will contain fixed data in the form of a structure of type _udp_icmp_message. The definition of this structure is:

typedef struct {
word myport;         // Originating port on this host
byte icmp_type;      // One of the ICMPTYPE_* values
byte icmp_code;      // The corresponding ICMP code
} _udp_icmp_message;

Please see sock_mode for more information about the modes UDP_MODE_ICMP and UDP_MODE_DICMP.

Parameters

s

Pointer to socket's data structure.

buffer

Buffer where the UDP datagram will be stored.

len

Maximum length of the buffer.

remip

IP address of the remote host of the received datagram.

remport

Port number of the remote host of the received datagram.

Return value

≥0: Number of bytes received.

-1: No datagram waiting.

-2: Error - not a UDP socket.

-3: The returned buffer contains an ICMP error which was queued previously.

Library

UDP.LIB

See also

udp_recv, udp_send, udp_sendto, udp_open, udp_peek