[Dnsmasq-discuss] [PATCH] pxe: support pxe clients with custom vendor-class

Simon Kelley simon at thekelleys.org.uk
Thu Dec 3 22:51:30 GMT 2020


The patch looks fine in princple, but it doesn't apply to the current
release (2.82) What version of dnsmasq were you patching?

Cheers,

Simon.



On 02/12/2020 12:23, Wang Shanker wrote:
> According to UEFI[1] and PXE[2] specs, PXE clients are required to have
> `PXEClient` identfier in the vendor-class field of DHCP requests, and
> PXE servers should also include that identifier in their responses.
> However, the firmware of servers from a few vendors[3] are customized to
> include a different identifier. This patch adds an option named
> `dhcp-pxe-vendor` to provide a list of such identifiers. The identifier
> used in responses sent from dnsmasq is identical to that in the coresponding
> request.
> 
> [1]: https://uefi.org/sites/default/files/resources/UEFI%20Spec%202.8B%20May%202020.pdf
> [2]: http://www.pix.net/software/pxeboot/archive/pxespec.pdf
> [3]: For instance, TaiShan servers from Huawei, which are Arm64-based,
> send `HW-Client` in PXE requests up to now.
> 
> Signed-off-by: Miao Wang <shankerwangmiao at gmail.com>
> ---
>  man/dnsmasq.8 | 15 ++++++++
>  src/dnsmasq.h |  9 +++++
>  src/option.c  | 27 ++++++++++++--
>  src/rfc2131.c | 97 +++++++++++++++++++++++++++++++++++++--------------
>  4 files changed, 120 insertions(+), 28 deletions(-)
> 
> diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
> index 2e5ef21..31ea0b4 100644
> --- a/man/dnsmasq.8
> +++ b/man/dnsmasq.8
> @@ -1426,6 +1426,21 @@ to allow netbooting. This mode is enabled using the
>  .B proxy
>  keyword in
>  .B dhcp-range.
> +.TP
> +.B --dhcp-pxe-vendor=<vendor>[,...]
> +According to UEFI and PXE specifications, DHCP packets between PXE clients and
> +proxy PXE servers should have 
> +.I PXEClient 
> +in their vendor-class field. However, the firmware of computers from a few
> +vendors is customized to carry a different identifier in that field. This option
> +is used to consider such identifiers valid for identifying PXE clients. For 
> +instance
> +
> +.B --dhcp-pxe-vendor=PXEClient,HW-Client
> +
> +will enable dnsmasq to also provide proxy PXE service to those PXE clients with
> +.I HW-Client
> +in as their identifier.
>  .TP  
>  .B \-X, --dhcp-lease-max=<number>
>  Limits dnsmasq to the specified maximum number of DHCP leases. The
> diff --git a/src/dnsmasq.h b/src/dnsmasq.h
> index 6b44e53..e654059 100644
> --- a/src/dnsmasq.h
> +++ b/src/dnsmasq.h
> @@ -768,6 +768,7 @@ struct dhcp_opt {
>  #define DHOPT_RFC3925         2048
>  #define DHOPT_TAGOK           4096
>  #define DHOPT_ADDR6           8192
> +#define DHOPT_VENDOR_PXE     16384
>  
>  struct dhcp_boot {
>    char *file, *sname, *tftp_sname;
> @@ -784,6 +785,8 @@ struct pxe_service {
>    struct pxe_service *next;
>  };
>  
> +#define DHCP_PXE_DEF_VENDOR      "PXEClient"
> +
>  #define MATCH_VENDOR     1
>  #define MATCH_USER       2
>  #define MATCH_CIRCUIT    3
> @@ -799,6 +802,11 @@ struct dhcp_vendor {
>    struct dhcp_vendor *next;
>  };
>  
> +struct dhcp_pxe_vendor {
> +  char *data;
> +  struct dhcp_pxe_vendor *next;
> +};
> +
>  struct dhcp_mac {
>    unsigned int mask;
>    int hwaddr_len, hwaddr_type;
> @@ -967,6 +975,7 @@ extern struct daemon {
>    struct ra_interface *ra_interfaces;
>    struct dhcp_config *dhcp_conf;
>    struct dhcp_opt *dhcp_opts, *dhcp_match, *dhcp_opts6, *dhcp_match6;
> +  struct dhcp_pxe_vendor *dhcp_pxe_vendors;
>    struct dhcp_vendor *dhcp_vendors;
>    struct dhcp_mac *dhcp_macs;
>    struct dhcp_boot *boot_config;
> diff --git a/src/option.c b/src/option.c
> index 0c38db3..0a9d18f 100644
> --- a/src/option.c
> +++ b/src/option.c
> @@ -159,6 +159,7 @@ struct myoption {
>  #define LOPT_SCRIPT_ARP    347
>  #define LOPT_DHCPTTL       348
>  #define LOPT_TFTP_MTU      349
> +#define LOPT_PXE_VENDOR    350
>   
>  #ifdef HAVE_GETOPT_LONG
>  static const struct option opts[] =  
> @@ -257,6 +258,7 @@ static const struct myoption opts[] =
>      { "dhcp-circuitid", 1, 0, LOPT_CIRCUIT },
>      { "dhcp-remoteid", 1, 0, LOPT_REMOTE },
>      { "dhcp-subscrid", 1, 0, LOPT_SUBSCR },
> +    { "dhcp-pxe-vendor", 1, 0, LOPT_PXE_VENDOR },
>      { "interface-name", 1, 0, LOPT_INTNAME },
>      { "dhcp-hostsfile", 1, 0, LOPT_DHCP_HOST },
>      { "dhcp-optsfile", 1, 0, LOPT_DHCP_OPTS },
> @@ -367,6 +369,7 @@ static struct {
>    { LOPT_CIRCUIT, ARG_DUP, "set:<tag>,<circuit>", gettext_noop("Map RFC3046 circuit-id to tag."), NULL },
>    { LOPT_REMOTE, ARG_DUP, "set:<tag>,<remote>", gettext_noop("Map RFC3046 remote-id to tag."), NULL },
>    { LOPT_SUBSCR, ARG_DUP, "set:<tag>,<remote>", gettext_noop("Map RFC3993 subscriber-id to tag."), NULL },
> +  { LOPT_PXE_VENDOR, ARG_DUP, "<vendor>[,...]", gettext_noop("Specify vendor class to match for PXE requests."), NULL },
>    { 'J', ARG_DUP, "tag:<tag>...", gettext_noop("Don't do DHCP for hosts with tag set."), NULL },
>    { LOPT_BROADCAST, ARG_DUP, "[=tag:<tag>...]", gettext_noop("Force broadcast replies for hosts with tag set."), NULL }, 
>    { 'k', OPT_NO_FORK, NULL, gettext_noop("Do NOT fork into the background, do NOT run in debug mode."), NULL },
> @@ -3336,8 +3339,8 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
>  	     new->val = opt_malloc(new->len);
>  	     memcpy(new->val + 1, arg, new->len - 1);
>  	     
> -	     new->u.vendor_class = (unsigned char *)"PXEClient";
> -	     new->flags = DHOPT_VENDOR;
> +	     new->u.vendor_class = NULL;
> +	     new->flags = DHOPT_VENDOR | DHOPT_VENDOR_PXE;
>  	     
>  	     if (comma && atoi_check(comma, &timeout))
>  	       *(new->val) = timeout;
> @@ -3626,6 +3629,19 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
>  	new->next = daemon->override_relays;
>  	daemon->override_relays = new;
>  	arg = comma;
> +	}
> +	  break;
> +
> +    case LOPT_PXE_VENDOR: /* --dhcp-pxe-vendor */
> +      {
> +        while (arg) {
> +	  struct dhcp_pxe_vendor *new = opt_malloc(sizeof(struct dhcp_pxe_vendor));
> +	  comma = split(arg);
> +          new->data = opt_string_alloc(arg);
> +	  new->next = daemon->dhcp_pxe_vendors;
> +	  daemon->dhcp_pxe_vendors = new;
> +	  arg = comma;
> +	}
>        }
>        break;
>  
> @@ -4762,6 +4778,13 @@ void read_opts(int argc, char **argv, char *compile_opts)
>        strcat(buff, daemon->authserver);
>        daemon->hostmaster = opt_string_alloc(buff);
>      }
> +
> +  if (!daemon->dhcp_pxe_vendors)
> +    {
> +      daemon->dhcp_pxe_vendors = opt_malloc(sizeof(struct dhcp_pxe_vendor));
> +      daemon->dhcp_pxe_vendors->data = opt_string_alloc(DHCP_PXE_DEF_VENDOR);
> +      daemon->dhcp_pxe_vendors->next = NULL;
> +    }
>    
>    /* only one of these need be specified: the other defaults to the host-name */
>    if (option_bool(OPT_LOCALMX) || daemon->mxnames || daemon->mxtarget)
> diff --git a/src/rfc2131.c b/src/rfc2131.c
> index 3e97402..e408337 100644
> --- a/src/rfc2131.c
> +++ b/src/rfc2131.c
> @@ -30,7 +30,7 @@ static struct in_addr server_id(struct dhcp_context *context, struct in_addr ove
>  static unsigned int calc_time(struct dhcp_context *context, struct dhcp_config *config, unsigned char *opt);
>  static void option_put(struct dhcp_packet *mess, unsigned char *end, int opt, int len, unsigned int val);
>  static void option_put_string(struct dhcp_packet *mess, unsigned char *end, 
> -			      int opt, char *string, int null_term);
> +			      int opt, const char *string, int null_term);
>  static struct in_addr option_addr(unsigned char *opt);
>  static unsigned int option_uint(unsigned char *opt, int i, int size);
>  static void log_packet(char *type, void *addr, unsigned char *ext_mac, 
> @@ -54,16 +54,18 @@ static void do_options(struct dhcp_context *context,
>  		       int vendor_class_len,
>  		       time_t now,
>  		       unsigned int lease_time,
> -		       unsigned short fuzz);
> +		       unsigned short fuzz,
> +		       const char *pxevendor);
>  
>  
>  static void match_vendor_opts(unsigned char *opt, struct dhcp_opt *dopt); 
>  static int do_encap_opts(struct dhcp_opt *opts, int encap, int flag, struct dhcp_packet *mess, unsigned char *end, int null_term);
> -static void pxe_misc(struct dhcp_packet *mess, unsigned char *end, unsigned char *uuid);
> +static void pxe_misc(struct dhcp_packet *mess, unsigned char *end, unsigned char *uuid, const char *pxevendor);
>  static int prune_vendor_opts(struct dhcp_netid *netid);
>  static struct dhcp_opt *pxe_opts(int pxe_arch, struct dhcp_netid *netid, struct in_addr local, time_t now);
>  struct dhcp_boot *find_boot(struct dhcp_netid *netid);
>  static int pxe_uefi_workaround(int pxe_arch, struct dhcp_netid *netid, struct dhcp_packet *mess, struct in_addr local, time_t now, int pxe);
> +static int is_pxe_client(struct dhcp_packet *mess, size_t sz, const char **pxe_vendor);
>    
>  size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>  		  size_t sz, time_t now, int unicast_dest, int *is_inform, int pxe, struct in_addr fallback)
> @@ -74,6 +76,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>    struct dhcp_mac *mac;
>    struct dhcp_netid_list *id_list;
>    int clid_len = 0, ignore = 0, do_classes = 0, selecting = 0, pxearch = -1;
> +  const char *pxevendor = NULL;
>    struct dhcp_packet *mess = (struct dhcp_packet *)daemon->dhcp_packet.iov_base;
>    unsigned char *end = (unsigned char *)(mess + 1); 
>    unsigned char *real_end = (unsigned char *)(mess + 1); 
> @@ -613,7 +616,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>  	      
>  	      clear_packet(mess, end, 0);
>  	      do_options(context, mess, end, NULL, hostname, get_domain(mess->yiaddr), 
> -			 netid, subnet_addr, 0, 0, -1, NULL, vendor_class_len, now, 0xffffffff, 0);
> +			 netid, subnet_addr, 0, 0, -1, NULL, vendor_class_len, now, 0xffffffff, 0, NULL);
>  	    }
>  	}
>        
> @@ -770,9 +773,8 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>      clid = NULL;
>            
>    /* Check if client is PXE client. */
> -  if (daemon->enable_pxe && 
> -      (opt = option_find(mess, sz, OPTION_VENDOR_ID, 9)) && 
> -      strncmp(option_ptr(opt, 0), "PXEClient", 9) == 0)
> +  if (daemon->enable_pxe &&
> +      is_pxe_client(mess, sz, &pxevendor))
>      {
>        if ((opt = option_find(mess, sz, OPTION_PXE_UUID, 17)))
>  	{
> @@ -831,7 +833,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>  	  
>  	  option_put(mess, end, OPTION_MESSAGE_TYPE, 1, DHCPACK);
>  	  option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, htonl(context->local.s_addr));
> -	  pxe_misc(mess, end, uuid);
> +	  pxe_misc(mess, end, uuid, pxevendor);
>  	  
>  	  prune_vendor_opts(tagif_netid);
>  	  opt71.val = save71;
> @@ -911,7 +913,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>  		  option_put(mess, end, OPTION_MESSAGE_TYPE, 1, 
>  			     mess_type == DHCPDISCOVER ? DHCPOFFER : DHCPACK);
>  		  option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, htonl(tmp->local.s_addr));
> -		  pxe_misc(mess, end, uuid);
> +		  pxe_misc(mess, end, uuid, pxevendor);
>  		  prune_vendor_opts(tagif_netid);
>  		  if ((pxe && !workaround) || !redirect4011)
>  		    do_encap_opts(pxe_opts(pxearch, tagif_netid, tmp->local, now), OPTION_VENDOR_CLASS_OPT, DHOPT_VENDOR_MATCH, mess, end, 0);
> @@ -1068,7 +1070,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>        option_put(mess, end, OPTION_LEASE_TIME, 4, time);
>        /* T1 and T2 are required in DHCPOFFER by HP's wacky Jetdirect client. */
>        do_options(context, mess, end, req_options, offer_hostname, get_domain(mess->yiaddr), 
> -		 netid, subnet_addr, fqdn_flags, borken_opt, pxearch, uuid, vendor_class_len, now, time, fuzz);
> +		 netid, subnet_addr, fqdn_flags, borken_opt, pxearch, uuid, vendor_class_len, now, time, fuzz, pxevendor);
>        
>        return dhcp_packet_size(mess, agent_id, real_end);
>        
> @@ -1406,7 +1408,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>  	  option_put(mess, end, OPTION_SERVER_IDENTIFIER, INADDRSZ, ntohl(server_id(context, override, fallback).s_addr));
>  	  option_put(mess, end, OPTION_LEASE_TIME, 4, time);
>  	  do_options(context, mess, end, req_options, hostname, get_domain(mess->yiaddr), 
> -		     netid, subnet_addr, fqdn_flags, borken_opt, pxearch, uuid, vendor_class_len, now, time, fuzz);
> +		     netid, subnet_addr, fqdn_flags, borken_opt, pxearch, uuid, vendor_class_len, now, time, fuzz, pxevendor);
>  	}
>  
>        return dhcp_packet_size(mess, agent_id, real_end); 
> @@ -1471,7 +1473,7 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
>  	}
>  
>        do_options(context, mess, end, req_options, hostname, get_domain(mess->ciaddr),
> -		 netid, subnet_addr, fqdn_flags, borken_opt, pxearch, uuid, vendor_class_len, now, 0xffffffff, 0);
> +		 netid, subnet_addr, fqdn_flags, borken_opt, pxearch, uuid, vendor_class_len, now, 0xffffffff, 0, pxevendor);
>        
>        *is_inform = 1; /* handle reply differently */
>        return dhcp_packet_size(mess, agent_id, real_end); 
> @@ -1846,7 +1848,7 @@ static void option_put(struct dhcp_packet *mess, unsigned char *end, int opt, in
>  }
>  
>  static void option_put_string(struct dhcp_packet *mess, unsigned char *end, int opt, 
> -			      char *string, int null_term)
> +			      const char *string, int null_term)
>  {
>    unsigned char *p;
>    size_t len = strlen(string);
> @@ -1924,15 +1926,32 @@ static void match_vendor_opts(unsigned char *opt, struct dhcp_opt *dopt)
>        dopt->flags &= ~DHOPT_VENDOR_MATCH;
>        if (opt && (dopt->flags & DHOPT_VENDOR))
>  	{
> -	  int i, len = 0;
> -	  if (dopt->u.vendor_class)
> -	    len = strlen((char *)dopt->u.vendor_class);
> -	  for (i = 0; i <= (option_len(opt) - len); i++)
> -	    if (len == 0 || memcmp(dopt->u.vendor_class, option_ptr(opt, i), len) == 0)
> -	      {
> -		dopt->flags |= DHOPT_VENDOR_MATCH;
> -		break;
> -	      }
> +	  const struct dhcp_pxe_vendor *pv;
> +	  struct dhcp_pxe_vendor dummy_vendor = {
> +	    .data = (char *)dopt->u.vendor_class,
> +	    .next = NULL,
> +	  };
> +	  if (dopt->flags & DHOPT_VENDOR_PXE)
> +	    pv = daemon->dhcp_pxe_vendors;
> +	  else
> +	    pv = &dummy_vendor;
> +	  for (; pv; pv = pv->next)
> +	    {
> +	      int i, len = 0, matched = 0;
> +	      if (pv->data)
> +	        len = strlen(pv->data);
> +	      for (i = 0; i <= (option_len(opt) - len); i++)
> +	        if (len == 0 || memcmp(pv->data, option_ptr(opt, i), len) == 0)
> +	          {
> +		    matched = 1;
> +	            break;
> +	          }
> +	      if (matched)
> +		{
> +	          dopt->flags |= DHOPT_VENDOR_MATCH;
> +		  break;
> +		}
> +	    }
>  	}
>      }
>  }
> @@ -1985,11 +2004,13 @@ static int do_encap_opts(struct dhcp_opt *opt, int encap, int flag,
>    return ret;
>  }
>  
> -static void pxe_misc(struct dhcp_packet *mess, unsigned char *end, unsigned char *uuid)
> +static void pxe_misc(struct dhcp_packet *mess, unsigned char *end, unsigned char *uuid, const char *pxevendor)
>  {
>    unsigned char *p;
>  
> -  option_put_string(mess, end, OPTION_VENDOR_ID, "PXEClient", 0);
> +  if (!pxevendor)
> +    pxevendor="PXEClient";
> +  option_put_string(mess, end, OPTION_VENDOR_ID, pxevendor, 0);
>    if (uuid && (p = free_space(mess, end, OPTION_PXE_UUID, 17)))
>      memcpy(p, uuid, 17);
>  }
> @@ -2217,6 +2238,29 @@ struct dhcp_boot *find_boot(struct dhcp_netid *netid)
>    return boot;
>  }
>  
> +static int is_pxe_client(struct dhcp_packet *mess, size_t sz, const char **pxe_vendor)
> +{
> +  const unsigned char *opt = NULL;
> +  ssize_t conf_len = 0;
> +  const struct dhcp_pxe_vendor *conf = daemon->dhcp_pxe_vendors;
> +  opt = option_find(mess, sz, OPTION_VENDOR_ID, 0);
> +  if (!opt) 
> +    return 0;
> +  for (; conf; conf = conf->next)
> +    {
> +      conf_len = strlen(conf->data);
> +      if (option_len(opt) < conf_len)
> +        continue;
> +      if (strncmp(option_ptr(opt, 0), conf->data, conf_len) == 0)
> +        {
> +          if (pxe_vendor)
> +            *pxe_vendor = conf->data;
> +          return 1;
> +        }
> +    }
> +  return 0;
> +}
> +
>  static void do_options(struct dhcp_context *context,
>  		       struct dhcp_packet *mess,
>  		       unsigned char *end, 
> @@ -2231,7 +2275,8 @@ static void do_options(struct dhcp_context *context,
>  		       int vendor_class_len,
>  		       time_t now,
>  		       unsigned int lease_time,
> -		       unsigned short fuzz)
> +		       unsigned short fuzz,
> +		       const char *pxevendor)
>  {
>    struct dhcp_opt *opt, *config_opts = daemon->dhcp_opts;
>    struct dhcp_boot *boot;
> @@ -2605,7 +2650,7 @@ static void do_options(struct dhcp_context *context,
>    
>    if (context && pxe_arch != -1)
>      {
> -      pxe_misc(mess, end, uuid);
> +      pxe_misc(mess, end, uuid, pxevendor);
>        if (!pxe_uefi_workaround(pxe_arch, tagif, mess, context->local, now, 0))
>  	config_opts = pxe_opts(pxe_arch, tagif, context->local, now);
>      }
> 




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