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lwip-contrib-mac/apps/netbios/netbios.c

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#include "netbios.h"
#include "lwip/opt.h"
#include "lwip/udp.h"
#include "lwip/netif.h"
/** This is an example implementation of a NetBIOS name server.
* It responds to name queries for a configurable name.
* Name resolving is not supported.
*
* Note that the device doesn't broadcast it's own name so can't
* detect duplicate names!
*/
#if LWIP_UDP
/** default port number for "NetBIOS Name service */
#define NETBIOS_PORT 137
/** size of a NetBIOS name */
#define NETBIOS_NAME_LEN 16
/** NetBIOS name of LWIP device */
#define NETBIOS_LWIP_NAME "NETBIOSLWIPDEV"
/** The Time-To-Live for NetBIOS name responds (in seconds)
* Default is 300000 seconds (3 days, 11 hours, 20 minutes) */
#define NETBIOS_TTL 300000
/** NetBIOS header flags */
#define NETB_HFLAG_RESPONSE 0x8000
#define NETB_HFLAG_OPCODE 0x7800
#define NETB_HFLAG_OPCODE_NAME_QUERY 0x0000
#define NETB_HFLAG_AUTHORATIVE 0x0400
#define NETB_HFLAG_TRUNCATED 0x0200
#define NETB_HFLAG_RECURS_DESIRED 0x0100
#define NETB_HFLAG_RECURS_AVAILABLE 0x0080
#define NETB_HFLAG_BROADCAST 0x0010
#define NETB_HFLAG_REPLYCODE 0x0008
#define NETB_HFLAG_REPLYCODE_NOERROR 0x0000
/** NetBIOS name flags */
#define NETB_NFLAG_UNIQUE 0x8000
#define NETB_NFLAG_NODETYPE 0x6000
#define NETB_NFLAG_NODETYPE_HNODE 0x6000
#define NETB_NFLAG_NODETYPE_MNODE 0x4000
#define NETB_NFLAG_NODETYPE_PNODE 0x2000
#define NETB_NFLAG_NODETYPE_BNODE 0x0000
/** NetBIOS message header */
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct netbios_hdr {
PACK_STRUCT_FIELD(u16_t trans_id);
PACK_STRUCT_FIELD(u16_t flags);
PACK_STRUCT_FIELD(u16_t questions);
PACK_STRUCT_FIELD(u16_t answerRRs);
PACK_STRUCT_FIELD(u16_t authorityRRs);
PACK_STRUCT_FIELD(u16_t additionalRRs);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif
/** NetBIOS message name part */
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct netbios_name_hdr {
PACK_STRUCT_FIELD(u8_t nametype);
PACK_STRUCT_FIELD(u8_t encname[(NETBIOS_NAME_LEN*2)+1]);
PACK_STRUCT_FIELD(u16_t type);
PACK_STRUCT_FIELD(u16_t class);
PACK_STRUCT_FIELD(u32_t ttl);
PACK_STRUCT_FIELD(u16_t datalen);
PACK_STRUCT_FIELD(u16_t flags);
PACK_STRUCT_FIELD(u32_t addr);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif
/* @todo: does this have to be packed, too? */
struct netbios_resp
{
struct netbios_hdr resp_hdr;
struct netbios_name_hdr resp_name;
};
/** NetBIOS decoding name */
static int
netbios_name_decoding( char *name_enc, char *name_dec, int name_dec_len)
{
char *pname;
char cname;
char cnbname;
int index = 0;
/* Start decoding netbios name. */
pname = name_enc;
for (;;) {
/* Every two characters of the first level-encoded name
* turn into one character in the decoded name. */
cname = *pname;
if (cname == '\0')
break; /* no more characters */
if (cname == '.')
break; /* scope ID follows */
if (cname < 'A' || cname > 'Z') {
/* Not legal. */
return -1;
}
cname -= 'A';
cnbname = cname << 4;
pname++;
cname = *pname;
if (cname == '\0' || cname == '.') {
/* No more characters in the name - but we're in
* the middle of a pair. Not legal. */
return -1;
}
if (cname < 'A' || cname > 'Z') {
/* Not legal. */
return -1;
}
cname -= 'A';
cnbname |= cname;
pname++;
/* Do we have room to store the character? */
if (index < NETBIOS_NAME_LEN) {
/* Yes - store the character. */
name_dec[index++] = (cnbname!=' '?cnbname:'\0');
}
}
return 0;
}
/** NetBIOS encoding name */
static int
netbios_name_encoding(char *name_enc, char *name_dec, int name_dec_len)
{
char *pname;
char cname;
unsigned char ucname;
int index = 0;
/* Start encoding netbios name. */
pname = name_enc;
for (;;) {
/* Every two characters of the first level-encoded name
* turn into one character in the decoded name. */
cname = *pname;
if (cname == '\0')
break; /* no more characters */
if (cname == '.')
break; /* scope ID follows */
if ((cname < 'A' || cname > 'Z') && (cname < '0' || cname > '9')) {
/* Not legal. */
return -1;
}
/* Do we have room to store the character? */
if (index >= name_dec_len) {
return -1;
}
/* Yes - store the character. */
ucname = cname;
name_dec[index++] = ('A'+((ucname>>4) & 0x0F));
name_dec[index++] = ('A'+( ucname & 0x0F));
pname++;
}
/* Fill with "space" coding */
for (;index<name_dec_len-1;) {
name_dec[index++] = 'C';
name_dec[index++] = 'A';
}
/* Terminate string */
name_dec[index]='\0';
return 0;
}
/** NetBIOS Name service recv callback */
static void
netbios_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, struct ip_addr *addr, u16_t port)
{
/* if packet is valid */
if (p != NULL) {
char netbios_name[NETBIOS_NAME_LEN+1];
struct netbios_hdr* netbios_hdr = p->payload;
struct netbios_name_hdr* netbios_name_hdr = (struct netbios_name_hdr*)(netbios_hdr+1);
/* @todo: do we need to check answerRRs/authorityRRs/additionalRRs? */
/* if the packet is a NetBIOS name query question */
if (((ntohs(netbios_hdr->flags) & NETB_HFLAG_OPCODE) == NETB_HFLAG_OPCODE_NAME_QUERY) &&
((ntohs(netbios_hdr->flags) & NETB_HFLAG_RESPONSE) == 0) &&
(ntohs(netbios_hdr->questions) == 1)) {
/* decode the NetBIOS name */
netbios_name_decoding( netbios_name_hdr->encname, netbios_name, sizeof(netbios_name));
/* if the packet is for us */
if (strcmp( netbios_name, NETBIOS_LWIP_NAME)==0) {
struct pbuf *q;
struct netbios_resp *resp;
q = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct netbios_resp), PBUF_RAM);
if (q != NULL) {
resp = (struct netbios_resp*)q->payload;
/* prepare NetBIOS header response */
resp->resp_hdr.trans_id = netbios_hdr->trans_id;
resp->resp_hdr.flags = htons(NETB_HFLAG_RESPONSE |
NETB_HFLAG_OPCODE_NAME_QUERY |
NETB_HFLAG_AUTHORATIVE |
NETB_HFLAG_RECURS_DESIRED);
resp->resp_hdr.questions = 0;
resp->resp_hdr.answerRRs = htons(1);
resp->resp_hdr.authorityRRs = 0;
resp->resp_hdr.additionalRRs = 0;
/* prepare NetBIOS header datas */
memcpy( resp->resp_name.encname, netbios_name_hdr->encname, sizeof(netbios_name_hdr->encname));
resp->resp_name.nametype = netbios_name_hdr->nametype;
resp->resp_name.type = netbios_name_hdr->type;
resp->resp_name.class = netbios_name_hdr->class;
resp->resp_name.ttl = htonl(NETBIOS_TTL);
resp->resp_name.datalen = htons(sizeof(resp->resp_name.flags)+sizeof(resp->resp_name.addr));
resp->resp_name.flags = htons(NETB_NFLAG_NODETYPE_BNODE);
resp->resp_name.addr = netif_default->ip_addr.addr;
/* send the NetBIOS response */
udp_sendto(upcb, q, addr, port);
/* free the "reference" pbuf */
pbuf_free(q);
}
}
}
/* free the pbuf */
pbuf_free(p);
}
}
void netbios_init(void)
{
struct udp_pcb *pcb;
LWIP_ASSERT("NetBIOS name is too long!", strlen(NETBIOS_LWIP_NAME) < NETBIOS_NAME_LEN);
pcb = udp_new();
if (pcb != NULL) {
udp_bind(pcb, IP_ADDR_ANY, NETBIOS_PORT);
udp_recv(pcb, netbios_recv, pcb);
}
}
#endif /* LWIP_UDP */
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