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net: ppp: ipcp: Improvements to DNS option negotiation #93181

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Merged
merged 2 commits into from
Jul 19, 2025
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Merged

net: ppp: ipcp: Improvements to DNS option negotiation #93181

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774e2dc
net: ppp: ipcp: Don't request DNS if not needed
SeppoTakalo Jul 16, 2025
d7f78e5
net: ppp: Allow peer-options to be rejected
SeppoTakalo Jul 16, 2025
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4 changes: 4 additions & 0 deletions include/zephyr/net/ppp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -353,7 +353,11 @@ struct ppp_my_option_data {
uint32_t flags;
};

#if defined(CONFIG_NET_L2_PPP_OPTION_DNS_USE)
#define IPCP_NUM_MY_OPTIONS 3
#else
#define IPCP_NUM_MY_OPTIONS 1
#endif
#define IPV6CP_NUM_MY_OPTIONS 1

enum ppp_flags {
Expand Down
93 changes: 64 additions & 29 deletions subsys/net/l2/ppp/ipcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,16 +42,6 @@ static int ipcp_add_ip_address(struct ppp_context *ctx, struct net_pkt *pkt)
return ipcp_add_address(ctx, pkt, &ctx->ipcp.my_options.address);
}

static int ipcp_add_dns1(struct ppp_context *ctx, struct net_pkt *pkt)
{
return ipcp_add_address(ctx, pkt, &ctx->ipcp.my_options.dns1_address);
}

static int ipcp_add_dns2(struct ppp_context *ctx, struct net_pkt *pkt)
{
return ipcp_add_address(ctx, pkt, &ctx->ipcp.my_options.dns2_address);
}

static int ipcp_ack_check_address(struct net_pkt *pkt, size_t oplen,
struct in_addr *addr)
{
Expand Down Expand Up @@ -81,20 +71,6 @@ static int ipcp_ack_ip_address(struct ppp_context *ctx, struct net_pkt *pkt,
&ctx->ipcp.my_options.address);
}

static int ipcp_ack_dns1(struct ppp_context *ctx, struct net_pkt *pkt,
uint8_t oplen)
{
return ipcp_ack_check_address(pkt, oplen,
&ctx->ipcp.my_options.dns1_address);
}

static int ipcp_ack_dns2(struct ppp_context *ctx, struct net_pkt *pkt,
uint8_t oplen)
{
return ipcp_ack_check_address(pkt, oplen,
&ctx->ipcp.my_options.dns2_address);
}

static int ipcp_nak_override_address(struct net_pkt *pkt, size_t oplen,
struct in_addr *addr)
{
Expand All @@ -112,6 +88,31 @@ static int ipcp_nak_ip_address(struct ppp_context *ctx, struct net_pkt *pkt,
&ctx->ipcp.my_options.address);
}

#if defined(CONFIG_NET_L2_PPP_OPTION_DNS_USE)
static int ipcp_add_dns1(struct ppp_context *ctx, struct net_pkt *pkt)
{
return ipcp_add_address(ctx, pkt, &ctx->ipcp.my_options.dns1_address);
}

static int ipcp_add_dns2(struct ppp_context *ctx, struct net_pkt *pkt)
{
return ipcp_add_address(ctx, pkt, &ctx->ipcp.my_options.dns2_address);
}

static int ipcp_ack_dns1(struct ppp_context *ctx, struct net_pkt *pkt,
uint8_t oplen)
{
return ipcp_ack_check_address(pkt, oplen,
&ctx->ipcp.my_options.dns1_address);
}

static int ipcp_ack_dns2(struct ppp_context *ctx, struct net_pkt *pkt,
uint8_t oplen)
{
return ipcp_ack_check_address(pkt, oplen,
&ctx->ipcp.my_options.dns2_address);
}

static int ipcp_nak_dns1(struct ppp_context *ctx, struct net_pkt *pkt,
uint8_t oplen)
{
Expand All @@ -125,21 +126,24 @@ static int ipcp_nak_dns2(struct ppp_context *ctx, struct net_pkt *pkt,
return ipcp_nak_override_address(pkt, oplen,
&ctx->ipcp.my_options.dns2_address);
}
#endif /* CONFIG_NET_L2_PPP_OPTION_DNS_USE */

static const struct ppp_my_option_info ipcp_my_options[] = {
PPP_MY_OPTION(IPCP_OPTION_IP_ADDRESS, ipcp_add_ip_address,
ipcp_ack_ip_address, ipcp_nak_ip_address),
#if defined(CONFIG_NET_L2_PPP_OPTION_DNS_USE)
PPP_MY_OPTION(IPCP_OPTION_DNS1, ipcp_add_dns1,
ipcp_ack_dns1, ipcp_nak_dns1),
PPP_MY_OPTION(IPCP_OPTION_DNS2, ipcp_add_dns2,
ipcp_ack_dns2, ipcp_nak_dns2),
#endif
};

BUILD_ASSERT(ARRAY_SIZE(ipcp_my_options) == IPCP_NUM_MY_OPTIONS);

static struct net_pkt *ipcp_config_info_add(struct ppp_fsm *fsm)
{
return ppp_my_options_add(fsm, 3 * IP_ADDRESS_OPTION_LEN);
return ppp_my_options_add(fsm, IPCP_NUM_MY_OPTIONS * IP_ADDRESS_OPTION_LEN);
}

struct ipcp_peer_option_data {
Expand Down Expand Up @@ -224,6 +228,37 @@ static int ipcp_server_nak_ip_address(struct ppp_fsm *fsm,
#endif

#if defined(CONFIG_NET_L2_PPP_OPTION_SERVE_DNS)

static int ipcp_dns1_address_parse(struct ppp_fsm *fsm, struct net_pkt *pkt,
void *user_data)
{
struct ppp_context *ctx =
CONTAINER_OF(fsm, struct ppp_context, ipcp.fsm);
int ret;

ret = ipcp_dns_address_parse(fsm, pkt, user_data);

if (ret == -EINVAL && ctx->ipcp.peer_options.dns1_address.s_addr == INADDR_ANY) {
return -ENOTSUP;
}
return ret;
}

static int ipcp_dns2_address_parse(struct ppp_fsm *fsm, struct net_pkt *pkt,
void *user_data)
{
struct ppp_context *ctx =
CONTAINER_OF(fsm, struct ppp_context, ipcp.fsm);
int ret;

ret = ipcp_dns_address_parse(fsm, pkt, user_data);

if (ret == -EINVAL && ctx->ipcp.peer_options.dns2_address.s_addr == INADDR_ANY) {
return -ENOTSUP;
}
return ret;
}

static int ipcp_server_nak_dns1_address(struct ppp_fsm *fsm,
struct net_pkt *ret_pkt,
void *user_data)
Expand All @@ -232,7 +267,7 @@ static int ipcp_server_nak_dns1_address(struct ppp_fsm *fsm,
CONTAINER_OF(fsm, struct ppp_context, ipcp.fsm);

(void)net_pkt_write_u8(ret_pkt, IPCP_OPTION_DNS1);
ipcp_add_dns1(ctx, ret_pkt);
(void)ipcp_add_address(ctx, ret_pkt, &ctx->ipcp.peer_options.dns1_address);

return 0;
}
Expand All @@ -245,7 +280,7 @@ static int ipcp_server_nak_dns2_address(struct ppp_fsm *fsm,
CONTAINER_OF(fsm, struct ppp_context, ipcp.fsm);

(void)net_pkt_write_u8(ret_pkt, IPCP_OPTION_DNS2);
ipcp_add_dns2(ctx, ret_pkt);
(void)ipcp_add_address(ctx, ret_pkt, &ctx->ipcp.peer_options.dns2_address);

return 0;
}
Expand All @@ -259,9 +294,9 @@ static const struct ppp_peer_option_info ipcp_peer_options[] = {
PPP_PEER_OPTION(IPCP_OPTION_IP_ADDRESS, ipcp_ip_address_parse, NULL),
#endif
#if defined(CONFIG_NET_L2_PPP_OPTION_SERVE_DNS)
PPP_PEER_OPTION(IPCP_OPTION_DNS1, ipcp_dns_address_parse,
PPP_PEER_OPTION(IPCP_OPTION_DNS1, ipcp_dns1_address_parse,
ipcp_server_nak_dns1_address),
PPP_PEER_OPTION(IPCP_OPTION_DNS2, ipcp_dns_address_parse,
PPP_PEER_OPTION(IPCP_OPTION_DNS2, ipcp_dns2_address_parse,
ipcp_server_nak_dns2_address),
#endif
};
Expand Down
30 changes: 29 additions & 1 deletion subsys/net/l2/ppp/options.c
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Original file line number Diff line number Diff line change
Expand Up @@ -144,14 +144,38 @@ static int ppp_parse_option_conf_req_supported(struct net_pkt *pkt,
{
struct ppp_parse_option_conf_req_data *parse_data = user_data;
struct ppp_fsm *fsm = parse_data->fsm;
struct net_pkt *ret_pkt = parse_data->ret_pkt;
struct net_pkt_cursor cursor;
const struct ppp_peer_option_info *option_info =
ppp_peer_option_info_get(parse_data->options_info,
parse_data->num_options_info,
code);
int ret;

net_pkt_cursor_backup(pkt, &cursor);
ret = option_info->parse(fsm, pkt, parse_data->user_data);
if (ret == -EINVAL) {
if (ret == -ENOTSUP) {
net_pkt_cursor_restore(pkt, &cursor);
parse_data->rej_count++;
if (parse_data->nack_count != 0) {
/* Remove any NACKed data, if we need to reject something first */
net_pkt_update_length(ret_pkt, 0);
net_pkt_cursor_init(ret_pkt);
parse_data->nack_count = 0;
}
net_pkt_write_u8(ret_pkt, code);
net_pkt_write_u8(ret_pkt, len + sizeof(code) + sizeof(len));
if (len > 0) {
net_pkt_copy(ret_pkt, pkt, len);
}
return 0;
} else if (ret == -EINVAL) {
if (parse_data->rej_count != 0) {
/* If we have already rejected some options, we
* cannot NACK anything in the same packet.
*/
return 0;
}
parse_data->nack_count++;
ret = option_info->nack(fsm, parse_data->ret_pkt,
parse_data->user_data);
Expand Down Expand Up @@ -202,6 +226,10 @@ int ppp_config_info_req(struct ppp_fsm *fsm,
return -EINVAL;
}

if (parse_data.rej_count) {
return PPP_CONFIGURE_REJ;
}

if (parse_data.nack_count) {
return PPP_CONFIGURE_NACK;
}
Expand Down