On Fri, Apr 11, 2025 at 03:10:23PM +0200, Laurent Vivier wrote:No functional change. Currently, if dhcpv6_opt() is called with offset set to 0, it will set the offset to point to DHCPv6 options offset. To simplify the use of iovec_tail in a later patch, move the initialization out of the function. Replace all the call using 0 by a call using the offset of the DHCPv6 options. Signed-off-by: Laurent Vivier <lvivier(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au> As a rule, I dislike automagical special cases like this one in any case.--- dhcpv6.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/dhcpv6.c b/dhcpv6.c index 373a98869f9b..be51c278af7a 100644 --- a/dhcpv6.c +++ b/dhcpv6.c @@ -54,14 +54,14 @@ struct opt_hdr { uint16_t l; } __attribute__((packed)); +#define UDP_MSG_HDR_SIZE (sizeof(struct udphdr) + sizeof(struct msg_hdr)) # define OPT_SIZE_CONV(x) (htons_constant(x)) #define OPT_SIZE(x) OPT_SIZE_CONV(sizeof(struct opt_##x) - \ sizeof(struct opt_hdr)) #define OPT_VSIZE(x) (sizeof(struct opt_##x) - \ sizeof(struct opt_hdr)) #define OPT_MAX_SIZE IPV6_MIN_MTU - (sizeof(struct ipv6hdr) + \ - sizeof(struct udphdr) + \ - sizeof(struct msg_hdr)) + UDP_MSG_HDR_SIZE) /** * struct opt_client_id - DHCPv6 Client Identifier option @@ -290,8 +290,7 @@ static struct opt_hdr *dhcpv6_opt(const struct pool *p, size_t *offset, struct opt_hdr *o; size_t left; - if (!*offset) - *offset = sizeof(struct udphdr) + sizeof(struct msg_hdr); + ASSERT(*offset >= UDP_MSG_HDR_SIZE); while ((o = packet_get_try(p, 0, *offset, sizeof(*o), &left))) { unsigned int opt_len = ntohs(o->l) + sizeof(*o); @@ -327,7 +326,7 @@ static struct opt_hdr *dhcpv6_ia_notonlink(const struct pool *p, size_t offset; foreach(ia_type, ia_types) { - offset = 0; + offset = UDP_MSG_HDR_SIZE; while ((ia = dhcpv6_opt(p, &offset, *ia_type))) { if (ntohs(ia->l) < OPT_VSIZE(ia_na)) return NULL; @@ -464,8 +463,9 @@ static size_t dhcpv6_client_fqdn_fill(const struct pool *p, const struct ctx *c, o = (struct opt_client_fqdn *)(buf + offset); encode_domain_name(o->domain_name, c->fqdn); - req_opt = (struct opt_client_fqdn *)dhcpv6_opt(p, &(size_t){ 0 }, - OPT_CLIENT_FQDN); + req_opt = (struct opt_client_fqdn *)dhcpv6_opt(p, + &(size_t){ UDP_MSG_HDR_SIZE }, + OPT_CLIENT_FQDN); if (req_opt && req_opt->flags & 0x01 /* S flag */) o->flags = 0x02 /* O flag */; else @@ -522,15 +522,15 @@ int dhcpv6(struct ctx *c, const struct pool *p, if (!mh) return -1; - client_id = dhcpv6_opt(p, &(size_t){ 0 }, OPT_CLIENTID); + client_id = dhcpv6_opt(p, &(size_t){ UDP_MSG_HDR_SIZE }, OPT_CLIENTID); if (!client_id || ntohs(client_id->l) > OPT_VSIZE(client_id)) return -1; - server_id = dhcpv6_opt(p, &(size_t){ 0 }, OPT_SERVERID); + server_id = dhcpv6_opt(p, &(size_t){ UDP_MSG_HDR_SIZE }, OPT_SERVERID); if (server_id && ntohs(server_id->l) != OPT_VSIZE(server_id)) return -1; - ia = dhcpv6_opt(p, &(size_t){ 0 }, OPT_IA_NA); + ia = dhcpv6_opt(p, &(size_t){ UDP_MSG_HDR_SIZE }, OPT_IA_NA); if (ia && ntohs(ia->l) < MIN(OPT_VSIZE(ia_na), OPT_VSIZE(ia_ta))) return -1; @@ -580,7 +580,7 @@ int dhcpv6(struct ctx *c, const struct pool *p, memcmp(&resp.server_id, server_id, sizeof(resp.server_id))) return -1; - if (ia || dhcpv6_opt(p, &(size_t){ 0 }, OPT_IA_TA)) + if (ia || dhcpv6_opt(p, &(size_t){ UDP_MSG_HDR_SIZE }, OPT_IA_TA)) return -1; info("DHCPv6: received INFORMATION_REQUEST, sending REPLY");-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson