lwip_netbiosns.c

00001 /**
00002  * @file
00003  * NetBIOS name service responder
00004  */
00005 
00006 /**
00007  * @defgroup netbiosns NETBIOS responder
00008  * @ingroup apps
00009  *
00010  * This is an example implementation of a NetBIOS name server.
00011  * It responds to name queries for a configurable name.
00012  * Name resolving is not supported.
00013  *
00014  * Note that the device doesn't broadcast it's own name so can't
00015  * detect duplicate names!
00016  */
00017 
00018 /*
00019  * Redistribution and use in source and binary forms, with or without modification,
00020  * are permitted provided that the following conditions are met:
00021  *
00022  * 1. Redistributions of source code must retain the above copyright notice,
00023  *    this list of conditions and the following disclaimer.
00024  * 2. Redistributions in binary form must reproduce the above copyright notice,
00025  *    this list of conditions and the following disclaimer in the documentation
00026  *    and/or other materials provided with the distribution.
00027  * 3. The name of the author may not be used to endorse or promote products
00028  *    derived from this software without specific prior written permission.
00029  *
00030  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00031  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00032  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00033  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00034  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00035  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00036  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00037  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00038  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00039  * OF SUCH DAMAGE.
00040  *
00041  * This file is part of the lwIP TCP/IP stack.
00042  *
00043  */
00044 
00045 #include "lwip/apps/netbiosns.h"
00046 
00047 #if LWIP_IPV4 && LWIP_UDP  /* don't build if not configured for use in lwipopts.h */
00048 
00049 #include "lwip/def.h"
00050 #include "lwip/udp.h"
00051 #include "lwip/netif.h"
00052 
00053 #include <string.h>
00054 
00055 /** default port number for "NetBIOS Name service */
00056 #define NETBIOS_PORT     137
00057 
00058 /** size of a NetBIOS name */
00059 #define NETBIOS_NAME_LEN 16
00060 
00061 /** The Time-To-Live for NetBIOS name responds (in seconds)
00062  * Default is 300000 seconds (3 days, 11 hours, 20 minutes) */
00063 #define NETBIOS_NAME_TTL 300000u
00064 
00065 /** NetBIOS header flags */
00066 #define NETB_HFLAG_RESPONSE           0x8000U
00067 #define NETB_HFLAG_OPCODE             0x7800U
00068 #define NETB_HFLAG_OPCODE_NAME_QUERY  0x0000U
00069 #define NETB_HFLAG_AUTHORATIVE        0x0400U
00070 #define NETB_HFLAG_TRUNCATED          0x0200U
00071 #define NETB_HFLAG_RECURS_DESIRED     0x0100U
00072 #define NETB_HFLAG_RECURS_AVAILABLE   0x0080U
00073 #define NETB_HFLAG_BROADCAST          0x0010U
00074 #define NETB_HFLAG_REPLYCODE          0x0008U
00075 #define NETB_HFLAG_REPLYCODE_NOERROR  0x0000U
00076 
00077 /** NetBIOS name flags */
00078 #define NETB_NFLAG_UNIQUE             0x8000U
00079 #define NETB_NFLAG_NODETYPE           0x6000U
00080 #define NETB_NFLAG_NODETYPE_HNODE     0x6000U
00081 #define NETB_NFLAG_NODETYPE_MNODE     0x4000U
00082 #define NETB_NFLAG_NODETYPE_PNODE     0x2000U
00083 #define NETB_NFLAG_NODETYPE_BNODE     0x0000U
00084 
00085 /** NetBIOS message header */
00086 #ifdef PACK_STRUCT_USE_INCLUDES
00087 #  include "arch/bpstruct.h"
00088 #endif
00089 PACK_STRUCT_BEGIN
00090 struct netbios_hdr {
00091   PACK_STRUCT_FIELD(u16_t trans_id);
00092   PACK_STRUCT_FIELD(u16_t flags);
00093   PACK_STRUCT_FIELD(u16_t questions);
00094   PACK_STRUCT_FIELD(u16_t answerRRs);
00095   PACK_STRUCT_FIELD(u16_t authorityRRs);
00096   PACK_STRUCT_FIELD(u16_t additionalRRs);
00097 } PACK_STRUCT_STRUCT;
00098 PACK_STRUCT_END
00099 #ifdef PACK_STRUCT_USE_INCLUDES
00100 #  include "arch/epstruct.h"
00101 #endif
00102 
00103 /** NetBIOS message name part */
00104 #ifdef PACK_STRUCT_USE_INCLUDES
00105 #  include "arch/bpstruct.h"
00106 #endif
00107 PACK_STRUCT_BEGIN
00108 struct netbios_name_hdr {
00109   PACK_STRUCT_FLD_8(u8_t  nametype);
00110   PACK_STRUCT_FLD_8(u8_t  encname[(NETBIOS_NAME_LEN*2)+1]);
00111   PACK_STRUCT_FIELD(u16_t type);
00112   PACK_STRUCT_FIELD(u16_t cls);
00113   PACK_STRUCT_FIELD(u32_t ttl);
00114   PACK_STRUCT_FIELD(u16_t datalen);
00115   PACK_STRUCT_FIELD(u16_t flags);
00116   PACK_STRUCT_FLD_S(ip4_addr_p_t addr);
00117 } PACK_STRUCT_STRUCT;
00118 PACK_STRUCT_END
00119 #ifdef PACK_STRUCT_USE_INCLUDES
00120 #  include "arch/epstruct.h"
00121 #endif
00122 
00123 /** NetBIOS message */
00124 #ifdef PACK_STRUCT_USE_INCLUDES
00125 #  include "arch/bpstruct.h"
00126 #endif
00127 PACK_STRUCT_BEGIN
00128 struct netbios_resp
00129 {
00130   struct netbios_hdr      resp_hdr;
00131   struct netbios_name_hdr resp_name;
00132 } PACK_STRUCT_STRUCT;
00133 PACK_STRUCT_END
00134 #ifdef PACK_STRUCT_USE_INCLUDES
00135 #  include "arch/epstruct.h"
00136 #endif
00137 
00138 #ifdef NETBIOS_LWIP_NAME
00139 #define NETBIOS_LOCAL_NAME NETBIOS_LWIP_NAME
00140 #else
00141 static char netbiosns_local_name[NETBIOS_NAME_LEN];
00142 #define NETBIOS_LOCAL_NAME netbiosns_local_name
00143 #endif
00144 
00145 struct udp_pcb *netbiosns_pcb;
00146 
00147 /** Decode a NetBIOS name (from packet to string) */
00148 static int
00149 netbiosns_name_decode(char *name_enc, char *name_dec, int name_dec_len)
00150 {
00151   char *pname;
00152   char  cname;
00153   char  cnbname;
00154   int   idx = 0;
00155 
00156   LWIP_UNUSED_ARG(name_dec_len);
00157 
00158   /* Start decoding netbios name. */
00159   pname  = name_enc;
00160   for (;;) {
00161     /* Every two characters of the first level-encoded name
00162      * turn into one character in the decoded name. */
00163     cname = *pname;
00164     if (cname == '\0')
00165       break;    /* no more characters */
00166     if (cname == '.')
00167       break;    /* scope ID follows */
00168     if (cname < 'A' || cname > 'Z') {
00169       /* Not legal. */
00170       return -1;
00171     }
00172     cname -= 'A';
00173     cnbname = cname << 4;
00174     pname++;
00175 
00176     cname = *pname;
00177     if (cname == '\0' || cname == '.') {
00178       /* No more characters in the name - but we're in
00179        * the middle of a pair.  Not legal. */
00180       return -1;
00181     }
00182     if (cname < 'A' || cname > 'Z') {
00183       /* Not legal. */
00184       return -1;
00185     }
00186     cname -= 'A';
00187     cnbname |= cname;
00188     pname++;
00189 
00190     /* Do we have room to store the character? */
00191     if (idx < NETBIOS_NAME_LEN) {
00192       /* Yes - store the character. */
00193       name_dec[idx++] = (cnbname!=' '?cnbname:'\0');
00194     }
00195   }
00196 
00197   return 0;
00198 }
00199 
00200 #if 0 /* function currently unused */
00201 /** Encode a NetBIOS name (from string to packet) - currently unused because
00202     we don't ask for names. */
00203 static int
00204 netbiosns_name_encode(char *name_enc, char *name_dec, int name_dec_len)
00205 {
00206   char         *pname;
00207   char          cname;
00208   unsigned char ucname;
00209   int           idx = 0;
00210 
00211   /* Start encoding netbios name. */
00212   pname = name_enc;
00213 
00214   for (;;) {
00215     /* Every two characters of the first level-encoded name
00216      * turn into one character in the decoded name. */
00217     cname = *pname;
00218     if (cname == '\0')
00219       break;    /* no more characters */
00220     if (cname == '.')
00221       break;    /* scope ID follows */
00222     if ((cname < 'A' || cname > 'Z') && (cname < '0' || cname > '9')) {
00223       /* Not legal. */
00224       return -1;
00225     }
00226 
00227     /* Do we have room to store the character? */
00228     if (idx >= name_dec_len) {
00229       return -1;
00230     }
00231 
00232     /* Yes - store the character. */
00233     ucname = cname;
00234     name_dec[idx++] = ('A'+((ucname>>4) & 0x0F));
00235     name_dec[idx++] = ('A'+( ucname     & 0x0F));
00236     pname++;
00237   }
00238 
00239   /* Fill with "space" coding */
00240   for (;idx < name_dec_len - 1;) {
00241     name_dec[idx++] = 'C';
00242     name_dec[idx++] = 'A';
00243   }
00244 
00245   /* Terminate string */
00246   name_dec[idx] = '\0';
00247 
00248   return 0;
00249 }
00250 #endif /* 0 */
00251 
00252 /** NetBIOS Name service recv callback */
00253 static void
00254 netbiosns_recv(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *addr, u16_t port)
00255 {
00256   LWIP_UNUSED_ARG(arg);
00257 
00258   /* if packet is valid */
00259   if (p != NULL) {
00260     char   netbios_name[NETBIOS_NAME_LEN+1];
00261     struct netbios_hdr*      netbios_hdr      = (struct netbios_hdr*)p->payload;
00262     struct netbios_name_hdr* netbios_name_hdr = (struct netbios_name_hdr*)(netbios_hdr+1);
00263 
00264     /* we only answer if we got a default interface */
00265     if (netif_default != NULL) {
00266       /* @todo: do we need to check answerRRs/authorityRRs/additionalRRs? */
00267       /* if the packet is a NetBIOS name query question */
00268       if (((netbios_hdr->flags & PP_NTOHS(NETB_HFLAG_OPCODE)) == PP_NTOHS(NETB_HFLAG_OPCODE_NAME_QUERY)) &&
00269           ((netbios_hdr->flags & PP_NTOHS(NETB_HFLAG_RESPONSE)) == 0) &&
00270            (netbios_hdr->questions == PP_NTOHS(1))) {
00271         /* decode the NetBIOS name */
00272         netbiosns_name_decode((char*)(netbios_name_hdr->encname), netbios_name, sizeof(netbios_name));
00273         /* if the packet is for us */
00274         if (lwip_strnicmp(netbios_name, NETBIOS_LOCAL_NAME, sizeof(NETBIOS_LOCAL_NAME)) == 0) {
00275           struct pbuf *q;
00276           struct netbios_resp *resp;
00277 
00278           q = pbuf_alloc(PBUF_TRANSPORT, sizeof(struct netbios_resp), PBUF_RAM);
00279           if (q != NULL) {
00280             resp = (struct netbios_resp*)q->payload;
00281 
00282             /* prepare NetBIOS header response */
00283             resp->resp_hdr.trans_id      = netbios_hdr->trans_id;
00284             resp->resp_hdr.flags         = PP_HTONS(NETB_HFLAG_RESPONSE |
00285                                                  NETB_HFLAG_OPCODE_NAME_QUERY |
00286                                                  NETB_HFLAG_AUTHORATIVE |
00287                                                  NETB_HFLAG_RECURS_DESIRED);
00288             resp->resp_hdr.questions     = 0;
00289             resp->resp_hdr.answerRRs     = PP_HTONS(1);
00290             resp->resp_hdr.authorityRRs  = 0;
00291             resp->resp_hdr.additionalRRs = 0;
00292 
00293             /* prepare NetBIOS header datas */
00294             MEMCPY( resp->resp_name.encname, netbios_name_hdr->encname, sizeof(netbios_name_hdr->encname));
00295             resp->resp_name.nametype     = netbios_name_hdr->nametype;
00296             resp->resp_name.type         = netbios_name_hdr->type;
00297             resp->resp_name.cls          = netbios_name_hdr->cls;
00298             resp->resp_name.ttl          = PP_HTONL(NETBIOS_NAME_TTL);
00299             resp->resp_name.datalen      = PP_HTONS(sizeof(resp->resp_name.flags)+sizeof(resp->resp_name.addr));
00300             resp->resp_name.flags        = PP_HTONS(NETB_NFLAG_NODETYPE_BNODE);
00301             ip4_addr_copy(resp->resp_name.addr, *netif_ip4_addr(netif_default));
00302 
00303             /* send the NetBIOS response */
00304             udp_sendto(upcb, q, addr, port);
00305 
00306             /* free the "reference" pbuf */
00307             pbuf_free(q);
00308           }
00309         }
00310       }
00311     }
00312     /* free the pbuf */
00313     pbuf_free(p);
00314   }
00315 }
00316 
00317 /**
00318  * @ingroup netbiosns 
00319  * Init netbios responder
00320  */
00321 void
00322 netbiosns_init(void)
00323 {
00324 #ifdef NETBIOS_LWIP_NAME
00325   LWIP_ASSERT("NetBIOS name is too long!", strlen(NETBIOS_LWIP_NAME) < NETBIOS_NAME_LEN);
00326 #endif
00327 
00328   netbiosns_pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
00329   if (netbiosns_pcb != NULL) {
00330     /* we have to be allowed to send broadcast packets! */
00331     ip_set_option(netbiosns_pcb, SOF_BROADCAST);
00332     udp_bind(netbiosns_pcb, IP_ANY_TYPE, NETBIOS_PORT);
00333     udp_recv(netbiosns_pcb, netbiosns_recv, netbiosns_pcb);
00334   }
00335 }
00336 
00337 #ifndef NETBIOS_LWIP_NAME
00338 /**
00339  * @ingroup netbiosns 
00340  * Set netbios name. ATTENTION: the hostname must be less than 15 characters!
00341  */
00342 void
00343 netbiosns_set_name(const char* hostname)
00344 {
00345   size_t copy_len = strlen(hostname);
00346   LWIP_ASSERT("NetBIOS name is too long!", copy_len < NETBIOS_NAME_LEN);
00347   if (copy_len >= NETBIOS_NAME_LEN) {
00348     copy_len = NETBIOS_NAME_LEN - 1;
00349   }
00350   MEMCPY(netbiosns_local_name, hostname, copy_len + 1);
00351 }
00352 #endif
00353 
00354 /**
00355  * @ingroup netbiosns 
00356  * Stop netbios responder
00357  */
00358 void
00359 netbiosns_stop(void)
00360 {
00361   if (netbiosns_pcb != NULL) {
00362     udp_remove(netbiosns_pcb);
00363     netbiosns_pcb = NULL;
00364   }
00365 }
00366 
00367 #endif /* LWIP_IPV4 && LWIP_UDP */