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Add AdvSNACRouterFlag option to set the SNAC router bit #271

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Add AdvSNACRouterFlag option to set the SNAC router bit #271

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fed4fd4
Add AdvSNACRouterFlag
arkku May 19, 2025
b705507
Fix indentation
arkku May 19, 2025
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2 changes: 2 additions & 0 deletions CHANGES
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
2025/05/19 Add AdvSNACRouterFlag <Kimmo Kulovesi>

2024/12/31 Release v2.20
build: annotated/signed tags need a tweak to verify correctly
build: need awk for newer autoconf
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5 changes: 5 additions & 0 deletions defaults.h
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Expand Up @@ -168,6 +168,8 @@
#define DFLT_AdvIntervalOpt 0
#define DFLT_AdvHomeAgentInfo 0

#define DFLT_AdvSNACRouterFlag 0

/* Option types (defined also at least in glibc 2.2's netinet/icmp6.h) */

#ifndef ND_OPT_RTR_ADV_INTERVAL
Expand Down Expand Up @@ -242,6 +244,9 @@ struct nd_opt_dnssl_info_local {
#define ND_OPT_RDNSSI_FLAG_S 0x0008
#endif
#endif
#ifndef ND_RA_FLAG_SNAC_ROUTER
#define ND_RA_FLAG_SNAC_ROUTER 0x02
#endif

/* Captive Portal RFC 8910 */

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5 changes: 5 additions & 0 deletions gram.y
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Expand Up @@ -96,6 +96,7 @@ int yylex_destroy (void);
%token T_AdvHomeAgentFlag
%token T_AdvIntervalOpt
%token T_AdvHomeAgentInfo
%token T_AdvSNACRouterFlag

%token T_Base6Interface
%token T_Base6to4Interface
Expand Down Expand Up @@ -349,6 +350,10 @@ ifaceval : T_MinRtrAdvInterval NUMBER ';'
{
iface->mipv6.HomeAgentLifetime = $2;
}
| T_AdvSNACRouterFlag SWITCH ';'
{
iface->ra_header_info.AdvSNACRouterFlag = $2;
}
| T_UnicastOnly SWITCH ';'
{
iface->UnicastOnly = $2;
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1 change: 1 addition & 0 deletions interface.c
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Expand Up @@ -42,6 +42,7 @@ void iface_init_defaults(struct Interface *iface)
iface->ra_header_info.AdvRetransTimer = DFLT_AdvRetransTimer;
iface->ra_header_info.AdvCurHopLimit = DFLT_AdvCurHopLimit;
iface->ra_header_info.AdvHomeAgentFlag = DFLT_AdvHomeAgentFlag;
iface->ra_header_info.AdvSNACRouterFlag = DFLT_AdvSNACRouterFlag;

iface->mipv6.AdvIntervalOpt = DFLT_AdvIntervalOpt;
iface->mipv6.AdvHomeAgentInfo = DFLT_AdvHomeAgentInfo;
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8 changes: 8 additions & 0 deletions radvd.conf.5.man
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Expand Up @@ -528,6 +528,14 @@ Note: RFC4861's suggested default value is significantly longer: 7 days.

Default: 14400 seconds (4 hours)

.TP
.BR AdvSNACRouterFlag " " on | off

When set, indicates the router is a SNAC router (stub network auto
configuration, e.g., for IPv6-only stub networks).
Comment on lines +534 to +535
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Please link to the RFC here

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I don't think there is an official RFC yet, even though the bit has been assigned (ietf-wg-snac/draft-ietf-snac-simple#54)

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So add https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xhtml#icmpv6-parameters-11 and https://datatracker.ietf.org/doc/draft-ietf-6man-snac-router-ra-flag/ which can update when there is an official RFC.


Default: off

.TP
.BR DeprecatePrefix " " on | off

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1 change: 1 addition & 0 deletions radvd.h
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Expand Up @@ -89,6 +89,7 @@ struct Interface {
int AdvOtherConfigFlag;
uint8_t AdvCurHopLimit;
int AdvHomeAgentFlag;
int AdvSNACRouterFlag;
int32_t AdvDefaultLifetime; /* XXX: really uint16_t but we need to use -1 */
int AdvDefaultPreference;
uint32_t AdvReachableTime;
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3 changes: 3 additions & 0 deletions radvdump.c
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Expand Up @@ -177,6 +177,9 @@ static void print_ff(unsigned char *msg, int len, struct sockaddr_in6 *addr, int
if (!edefs || DFLT_AdvHomeAgentFlag != (ND_RA_FLAG_HOME_AGENT == (radvert->nd_ra_flags_reserved & ND_RA_FLAG_HOME_AGENT)))
printf("\tAdvHomeAgentFlag %s;\n", (radvert->nd_ra_flags_reserved & ND_RA_FLAG_HOME_AGENT) ? "on" : "off");

if (!edefs || DFLT_AdvHomeAgentFlag != (ND_RA_FLAG_SNAC_ROUTER == (radvert->nd_ra_flags_reserved & ND_RA_FLAG_SNAC_ROUTER)))
printf("\tAdvSNACRouterFlag %s;\n", (radvert->nd_ra_flags_reserved & ND_RA_FLAG_SNAC_ROUTER) ? "on" : "off");

/* Route Preferences and more specific routes */
/* XXX two middlemost bits from 8 bit field */
if (!edefs || (((radvert->nd_ra_flags_reserved & 0x18) >> 3) & 0xff) != DFLT_AdvDefaultPreference) {
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1 change: 1 addition & 0 deletions scanner.l
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Expand Up @@ -87,6 +87,7 @@ UnicastOnly { return T_UnicastOnly; }
UnrestrictedUnicast { return T_UnrestrictedUnicast; }
AdvRASolicitedUnicast { return T_AdvRASolicitedUnicast; }
AdvCaptivePortalAPI { return T_AdvCaptivePortalAPI; }
AdvSNACRouterFlag { return T_AdvSNACRouterFlag; }

Base6Interface { return T_Base6Interface; }
Base6to4Interface { return T_Base6to4Interface; }
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1 change: 1 addition & 0 deletions send.c
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Expand Up @@ -221,6 +221,7 @@ static void add_ra_header(struct safe_buffer *sb, struct ra_header_info const *r
radvert.nd_ra_flags_reserved |= (ra_header_info->AdvOtherConfigFlag) ? ND_RA_FLAG_OTHER : 0;
/* Mobile IPv6 ext */
radvert.nd_ra_flags_reserved |= (ra_header_info->AdvHomeAgentFlag) ? ND_RA_FLAG_HOME_AGENT : 0;
radvert.nd_ra_flags_reserved |= (ra_header_info->AdvSNACRouterFlag) ? ND_RA_FLAG_SNAC_ROUTER : 0;

radvert.nd_ra_router_lifetime = cease_adv ? 0 : htons(ra_header_info->AdvDefaultLifetime);
radvert.nd_ra_flags_reserved |= (ra_header_info->AdvDefaultPreference << ND_OPT_RI_PRF_SHIFT) & ND_OPT_RI_PRF_MASK;
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