memcpy segfaults, but not in windows Post: 93515

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Top Forums Programming memcpy segfaults, but not in windows Post 93515 by khoma on Monday 19th of December 2005 08:37:36 PM

12-19-2005

Registered User

memcpy segfaults, but not in windows

Hi

Having a lil trouble with a rather simple application I'm writing. It so happens that I have to copy some data using memcpy() and so far I've been doing just fine compiling it with VC.Net and running it on Windows XP. Now I'm trying to port the thing to Solaris (which shouldn't really be too big a deal) and for some reason it is causing problems.

Code:

int SendPacket(unsigned short packNo, const char* data, unsigned short sSize){
	int addrlen = sizeof(struct sockaddr);
	int iRet = 0;
	PutShortAt(buffer, OP_DATA);	// Insert DATA op code
	PutShortAt(buffer + 2, packNo);	// Insert packet number
	memcpy(buffer + 4, data, sSize); // Insert the actual data
	iRet = sendto(iSock, buffer, sSize + 4, 0, (struct sockaddr *)&sraddr,addrlen);	// Send packet

	printf("Sent %d bytes\n", iRet);
	return IOK;
}

The line which causes the segfault is the memcpy() line. Basically, what I'm trying to do is this;

const char* data contains 512 bytes of arbitrary data that is to be added to a 516 byte packet which will then be transmitted to a computer somewhere on the internet. Byte 4-516 will contain the data. The first 4 bytes in the packet are reserved for packet information in the form of two shorts. sSize is of course the data size.

Any ideas as to what may be causing this? Like I said earlier, it runs just fine on Windows (of course with the appropriate modifications to net code, winsock and such). Any help would be greatly appreciated.

khoma

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ldns_pkt_edns_data

ldns(3) 						     Library Functions Manual							   ldns(3)

NAME

       ldns_pkt_edns,	 ldns_pkt_edns_udp_size,   ldns_pkt_edns_extended_rcode,   ldns_pkt_edns_version,   ldns_pkt_edns_z,   ldns_pkt_edns_data,
       ldns_pkt_set_edns_udp_size, ldns_pkt_set_edns_extended_rcode, ldns_pkt_set_edns_version, ldns_pkt_set_edns_z, ldns_pkt_set_edns_data-

SYNOPSIS

       #include <stdint.h>
       #include <stdbool.h>

       #include <ldns/ldns.h>

       bool ldns_pkt_edns(const ldns_pkt *packet);

       uint16_t ldns_pkt_edns_udp_size(const ldns_pkt *packet);

       uint8_t ldns_pkt_edns_extended_rcode(const ldns_pkt *packet);

       uint8_t ldns_pkt_edns_version(const ldns_pkt *packet);

       uint16_t ldns_pkt_edns_z(const ldns_pkt *packet);

       ldns_rdf* ldns_pkt_edns_data(const ldns_pkt *packet);

       void ldns_pkt_set_edns_udp_size(ldns_pkt *packet, uint16_t s);

       void ldns_pkt_set_edns_extended_rcode(ldns_pkt *packet, uint8_t c);

       void ldns_pkt_set_edns_version(ldns_pkt *packet, uint8_t v);

       void ldns_pkt_set_edns_z(ldns_pkt *packet, uint16_t z);

       void ldns_pkt_set_edns_data(ldns_pkt *packet, ldns_rdf *data);

DESCRIPTION

       ldns_pkt_edns() returns true if this packet needs and EDNS rr to be sent.  At the moment the only reason is an expected packet size  larger
	      than 512 bytes, but for instance dnssec would be a good reason too.

	      packet: the packet to check
	      Returns true if packet needs edns rr

       ldns_pkt_edns_udp_size() return the packet's edns udp size
	      packet: the packet
	      Returns the size

       ldns_pkt_edns_extended_rcode() return the packet's edns extended rcode
	      packet: the packet
	      Returns the rcode

       ldns_pkt_edns_version() return the packet's edns version
	      packet: the packet
	      Returns the version

       ldns_pkt_edns_z() return the packet's edns z value
	      packet: the packet
	      Returns the z value

       ldns_pkt_edns_data() return the packet's edns data
	      packet: the packet
	      Returns the data

       ldns_pkt_set_edns_udp_size() Set the packet's edns udp size
	      packet: the packet
	      s: the size

       ldns_pkt_set_edns_extended_rcode() Set the packet's edns extended rcode
	      packet: the packet
	      c: the code

       ldns_pkt_set_edns_version() Set the packet's edns version
	      packet: the packet
	      v: the version

       ldns_pkt_set_edns_z() Set the packet's edns z value
	      packet: the packet
	      z: the value

       ldns_pkt_set_edns_data() Set the packet's edns data
	      packet: the packet
	      data: the data

AUTHOR

       The ldns team at NLnet Labs. Which consists out of Jelte Jansen and Miek Gieben.

REPORTING BUGS

       Please report bugs to ldns-team@nlnetlabs.nl or in our bugzilla at http://www.nlnetlabs.nl/bugs/index.html

COPYRIGHT

       Copyright (c) 2004 - 2006 NLnet Labs.

       Licensed under the BSD License. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO

       ldns_pkt.  And perldoc Net::DNS, RFC1034, RFC1035, RFC4033, RFC4034  and RFC4035.

REMARKS

       This manpage was automaticly generated from the ldns source code by use of Doxygen and some perl.

								    30 May 2006 							   ldns(3)