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Fix remote_ip not set in UDP recvfrom #21

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Merged
philljj merged 5 commits into from
Feb 9, 2026
Merged

Fix remote_ip not set in UDP recvfrom #21

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3f3cceb
UT to confirm remote_ip not being set in UDP recvfrom
danielinux Feb 9, 2026
51f67b1
Fix: setting ts->remote_ip in wolf_sock_recvfrom()
danielinux Feb 9, 2026
19a244b
wolfIP_sock_recvfrom: added more corner-cases UT
danielinux Feb 9, 2026
5abd3a8
Implemented hardening against spoofed local-ip packets
danielinux Feb 9, 2026
a7db693
Addressed copilot comments:
danielinux Feb 9, 2026
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175 changes: 175 additions & 0 deletions src/test/unit/unit.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1039,6 +1039,173 @@ START_TEST(test_udp_sendto_and_recvfrom)
}
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END_TEST

START_TEST(test_udp_recvfrom_sets_remote_ip)
{
struct wolfIP s;
int sd;
struct wolfIP_sockaddr_in sin;
uint8_t payload[4] = {0xAA, 0xBB, 0xCC, 0xDD};
uint8_t rxbuf[4] = {0};
struct wolfIP_sockaddr_in from;
socklen_t from_len = sizeof(from);
int ret;
ip4 local_ip = 0x0A000001U;
ip4 remote_ip = 0x0A000002U;
uint16_t local_port = 4001;
uint16_t remote_port = 5001;
struct tsocket *ts;

wolfIP_init(&s);
mock_link_init(&s);
wolfIP_ipconfig_set(&s, local_ip, 0xFFFFFF00U, 0);

sd = wolfIP_sock_socket(&s, AF_INET, IPSTACK_SOCK_DGRAM, WI_IPPROTO_UDP);
ck_assert_int_gt(sd, 0);

memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = ee16(local_port);
sin.sin_addr.s_addr = ee32(local_ip);
ret = wolfIP_sock_bind(&s, sd, (struct wolfIP_sockaddr *)&sin, sizeof(sin));
ck_assert_int_eq(ret, 0);

ts = &s.udpsockets[SOCKET_UNMARK(sd)];
ck_assert_uint_eq(ts->remote_ip, 0);

inject_udp_datagram(&s, TEST_PRIMARY_IF, remote_ip, local_ip, remote_port, local_port,
payload, sizeof(payload));

memset(&from, 0, sizeof(from));
ret = wolfIP_sock_recvfrom(&s, sd, rxbuf, sizeof(rxbuf), 0,
(struct wolfIP_sockaddr *)&from, &from_len);
ck_assert_int_eq(ret, (int)sizeof(payload));
ck_assert_mem_eq(rxbuf, payload, sizeof(payload));
ck_assert_uint_eq(from.sin_addr.s_addr, ee32(remote_ip));
ck_assert_uint_eq(ts->remote_ip, remote_ip);
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}
END_TEST

START_TEST(test_udp_recvfrom_null_src_addr_len)
{
struct wolfIP s;
int sd;
struct wolfIP_sockaddr_in sin;
uint8_t payload[4] = {0x11, 0x22, 0x33, 0x44};
uint8_t rxbuf[4] = {0};
int ret;
ip4 local_ip = 0x0A000001U;
ip4 remote_ip = 0x0A000002U;
uint16_t local_port = 4002;
uint16_t remote_port = 5002;

wolfIP_init(&s);
mock_link_init(&s);
wolfIP_ipconfig_set(&s, local_ip, 0xFFFFFF00U, 0);

sd = wolfIP_sock_socket(&s, AF_INET, IPSTACK_SOCK_DGRAM, WI_IPPROTO_UDP);
ck_assert_int_gt(sd, 0);

memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = ee16(local_port);
sin.sin_addr.s_addr = ee32(local_ip);
ret = wolfIP_sock_bind(&s, sd, (struct wolfIP_sockaddr *)&sin, sizeof(sin));
ck_assert_int_eq(ret, 0);

inject_udp_datagram(&s, TEST_PRIMARY_IF, remote_ip, local_ip, remote_port, local_port,
payload, sizeof(payload));

ret = wolfIP_sock_recvfrom(&s, sd, rxbuf, sizeof(rxbuf), 0, NULL, NULL);
ck_assert_int_eq(ret, (int)sizeof(payload));
ck_assert_mem_eq(rxbuf, payload, sizeof(payload));
}
END_TEST

START_TEST(test_udp_recvfrom_preserves_remote_ip)
{
struct wolfIP s;
int sd;
struct wolfIP_sockaddr_in sin;
uint8_t payload[4] = {0x55, 0x66, 0x77, 0x88};
uint8_t rxbuf[4] = {0};
struct wolfIP_sockaddr_in from;
socklen_t from_len = sizeof(from);
int ret;
ip4 local_ip = 0x0A000001U;
ip4 remote_ip = 0x0A000002U;
ip4 preset_remote_ip = 0x0A000099U;
uint16_t local_port = 4003;
uint16_t remote_port = 5003;
struct tsocket *ts;

wolfIP_init(&s);
mock_link_init(&s);
wolfIP_ipconfig_set(&s, local_ip, 0xFFFFFF00U, 0);

sd = wolfIP_sock_socket(&s, AF_INET, IPSTACK_SOCK_DGRAM, WI_IPPROTO_UDP);
ck_assert_int_gt(sd, 0);

memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = ee16(local_port);
sin.sin_addr.s_addr = ee32(local_ip);
ret = wolfIP_sock_bind(&s, sd, (struct wolfIP_sockaddr *)&sin, sizeof(sin));
ck_assert_int_eq(ret, 0);

ts = &s.udpsockets[SOCKET_UNMARK(sd)];
ts->remote_ip = preset_remote_ip;

inject_udp_datagram(&s, TEST_PRIMARY_IF, remote_ip, local_ip, remote_port, local_port,
payload, sizeof(payload));

memset(&from, 0, sizeof(from));
ret = wolfIP_sock_recvfrom(&s, sd, rxbuf, sizeof(rxbuf), 0,
(struct wolfIP_sockaddr *)&from, &from_len);
ck_assert_int_eq(ret, (int)sizeof(payload));
ck_assert_mem_eq(rxbuf, payload, sizeof(payload));
ck_assert_uint_eq(from.sin_addr.s_addr, ee32(remote_ip));
ck_assert_uint_eq(ts->remote_ip, preset_remote_ip);
}
END_TEST

START_TEST(test_udp_recvfrom_null_addrlen)
{
struct wolfIP s;
int sd;
struct wolfIP_sockaddr_in sin;
uint8_t payload[4] = {0x9A, 0xBC, 0xDE, 0xF0};
uint8_t rxbuf[4] = {0};
struct wolfIP_sockaddr_in from;
int ret;
ip4 local_ip = 0x0A000001U;
ip4 remote_ip = 0x0A000002U;
uint16_t local_port = 4004;
uint16_t remote_port = 5004;

wolfIP_init(&s);
mock_link_init(&s);
wolfIP_ipconfig_set(&s, local_ip, 0xFFFFFF00U, 0);

sd = wolfIP_sock_socket(&s, AF_INET, IPSTACK_SOCK_DGRAM, WI_IPPROTO_UDP);
ck_assert_int_gt(sd, 0);

memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = ee16(local_port);
sin.sin_addr.s_addr = ee32(local_ip);
ret = wolfIP_sock_bind(&s, sd, (struct wolfIP_sockaddr *)&sin, sizeof(sin));
ck_assert_int_eq(ret, 0);

inject_udp_datagram(&s, TEST_PRIMARY_IF, remote_ip, local_ip, remote_port, local_port,
payload, sizeof(payload));

memset(&from, 0, sizeof(from));
ret = wolfIP_sock_recvfrom(&s, sd, rxbuf, sizeof(rxbuf), 0,
(struct wolfIP_sockaddr *)&from, NULL);
ck_assert_int_eq(ret, -1);
}
END_TEST

START_TEST(test_sock_error_paths)
{
struct wolfIP s;
Expand Down Expand Up @@ -12082,6 +12249,14 @@ Suite *wolf_suite(void)
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_udp_sendto_and_recvfrom);
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_udp_recvfrom_sets_remote_ip);
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_udp_recvfrom_null_src_addr_len);
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_udp_recvfrom_preserves_remote_ip);
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_udp_recvfrom_null_addrlen);
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_dns_query_and_callback_a);
suite_add_tcase(s, tc_proto);
tcase_add_test(tc_proto, test_dhcp_parse_offer_and_ack);
Expand Down
6 changes: 5 additions & 1 deletion src/wolfip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2647,17 +2647,21 @@ int wolfIP_sock_recvfrom(struct wolfIP *s, int sockfd, void *buf, size_t len, in
if (SOCKET_UNMARK(sockfd) >= MAX_UDPSOCKETS)
return -WOLFIP_EINVAL;
ts = &s->udpsockets[SOCKET_UNMARK(sockfd)];
if (sin && !addrlen)
return -1;
if (sin && *addrlen < sizeof(struct wolfIP_sockaddr_in))
return -1;
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Outdated
if (addrlen) *addrlen = sizeof(struct wolfIP_sockaddr_in);
if (fifo_len(&ts->sock.udp.rxbuf) == 0)
return -WOLFIP_EAGAIN;
desc = fifo_peek(&ts->sock.udp.rxbuf);
udp = (struct wolfIP_udp_datagram *)(ts->rxmem + desc->pos + sizeof(*desc));
if (ts->remote_ip == 0)
ts->remote_ip = ee32(udp->ip.src);
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Outdated
if (sin) {
sin->sin_family = AF_INET;
sin->sin_port = ee16(udp->src_port);
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Outdated
sin->sin_addr.s_addr = ee32(ts->remote_ip);
sin->sin_addr.s_addr = udp->ip.src;
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Outdated
}
seg_len = ee16(udp->len) - UDP_HEADER_LEN;
if (seg_len > len)
Expand Down