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Correct fragment handling when sendig fragmented packets

This commit is contained in:
7u83 2022-09-18 08:53:49 +02:00
parent ae686f4634
commit 435b3f823e
1 changed files with 25 additions and 11 deletions
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36
src/cw/send.c
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@ -150,34 +150,51 @@ cw_init_capwap_packet( uint8_t * buf, int wbid ,int rid, bstr_t rmac, bstr_t wd)
return hlen*4;
}
/**
* Send a CAPWAP packet and fragment it if nececerry
* @param conn connection where to send packet over
* @param buf pointer to a buffer initialized with #cw_init_capwap_packet
* @param hlen length of header, which is the value returned by #cw_init_capwap_packet
* @param data payload
* @param len length of payload
*/
int cw_send_capwap_packet(struct cw_Conn * conn, uint8_t * buf, int hlen, uint8_t * data, int len)
{
int fragoffset,mtu;
int fragid;
/* get mtu and align it to 8 */
mtu = conn->mtu;
mtu &= ~3;
/* initialize fragid and fragoffset */
fragoffset = 0;
if (len + hlen > mtu)
fragid = conn->fragid++;
else
fragid = 0;
/* create all fragments */
while (len + hlen > mtu){
memcpy(buf+hlen,data+(fragoffset*8),mtu-hlen);
len -= (mtu - hlen);
cw_set_hdr_flags(buf,CAPWAP_FLAG_HDR_F,1);
cw_set_dword(buf+4, conn->fragid<<16 | fragoffset<<3 );
cw_set_dword(buf+4, fragid<<16 | fragoffset<<3 );
cw_dbg_pkt(DBG_PKT_OUT,conn,buf,mtu,(struct sockaddr*)&conn->addr);
if (conn->write(conn,buf,mtu)<0)
return -1;
fragoffset+=(mtu-hlen)/8;
cw_set_hdr_flags(buf,CAPWAP_FLAG_HDR_M,0);
cw_set_hdr_flags(buf,CAPWAP_FLAG_HDR_W,0);
hlen = 8;
cw_set_hdr_hlen(buf,hlen/4);
/* put rmac and wireless data only into the 1st fragment */
if (hlen!=8){
cw_set_hdr_flags(buf,CAPWAP_FLAG_HDR_M,0);
cw_set_hdr_flags(buf,CAPWAP_FLAG_HDR_W,0);
hlen = 8;
cw_set_hdr_hlen(buf,hlen/4);
}
}
if (fragoffset)
@ -187,13 +204,11 @@ int cw_send_capwap_packet(struct cw_Conn * conn, uint8_t * buf, int hlen, uint8_
memcpy(buf+hlen,data+(fragoffset*8),mtu-hlen);
cw_set_dword(buf+4, conn->fragid<<16 | fragoffset<<3 );
cw_set_dword(buf+4, fragid<<16 | fragoffset<<3 );
cw_dbg_pkt(DBG_PKT_OUT,conn,buf,len+hlen,(struct sockaddr*)&conn->addr);
return conn->write(conn,buf,len + hlen);
}
int
@ -201,7 +216,6 @@ cw_send_msg( struct cw_Conn * conn, uint8_t *msg)
{
uint8_t buf[MAX_MTU];
int hlen,msglen;
hlen = cw_init_capwap_packet(buf,1,0,NULL,NULL);
msglen = cw_get_msg_elems_len(msg) + 8;
return cw_send_capwap_packet(conn,buf,hlen,msg,msglen);