Merge pull request #3777 from cesanta/nocnfb

Correct #3775 CN fallback handling
This commit is contained in:
Sergio R. Caprile authored and GitHub committed 2026-11-13 11:42:42 -03:00
commit 053b8ed824
2 files changed
+32 -18

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+16 -9
View File
@@ -20082,17 +20082,20 @@ static int mg_tls_verify_cert_san(const uint8_t *der, size_t dersz,
const char *server_name,
struct mg_addr *ref_ip) {
struct mg_der_tlv root, field, name;
int r;
bool is_addr = ref_ip != NULL;
if (mg_der_parse((uint8_t *) der, dersz, &root) < 0) {
MG_ERROR(("failed to parse certificate"));
return -1;
}
if (mg_der_find_oid(&root, (uint8_t *) "\x55\x1d\x11", 3, &field) <= 0) {
if ((r = mg_der_find_oid(&root, (uint8_t *) "\x55\x1d\x11", 3, &field)) < 0) {
MG_ERROR(("failed to extract SAN"));
return -1;
} else if (r == 0) {
return 0; // No SAN
}
if (mg_der_parse(field.value, field.len, &field) < 0) {
MG_ERROR(("SAN is not a constructed object"));
if (mg_der_parse(field.value, field.len, &field) < 0 || field.type != 0x30) {
MG_ERROR(("SAN is not a constructed object")); // RFC 5280 4.2.1.6
return -1;
}
while (mg_der_next(&field, &name) > 0) {
@@ -20119,6 +20122,7 @@ static int mg_tls_verify_cert_san(const uint8_t *der, size_t dersz,
return 1; // and matches the host name
}
}
MG_ERROR(("Found SAN but does not match IP or DNS name"));
return -1;
}
@@ -20306,12 +20310,15 @@ static int mg_tls_recv_cert(struct mg_connection *c, bool is_client) {
// and store public key for further CertVerify step
if (tls->hostname[0] != '\0') {
struct mg_addr addr; // use aton_ so localhost evals as a name
bool is_addr = mg_aton_(mg_str_s(tls->hostname), &addr);
if (mg_tls_verify_cert_san(cert, certsz, tls->hostname,
is_addr ? &addr : NULL) <= 0 &&
(is_addr || // IP references require a matching SAN
mg_tls_verify_cert_cn(&ci->subj, tls->hostname) <= 0)) {
mg_error(c, "failed to verify hostname");
bool is_addr;
int san;
is_addr = mg_aton_(mg_str_s(tls->hostname), &addr);
san = mg_tls_verify_cert_san(cert, certsz, tls->hostname,
is_addr ? &addr : NULL);
if (san < 0 || // RFC 6125 6.4.4 allow legacy fallback to CN
(san == 0 && (is_addr || mg_tls_verify_cert_cn(
&ci->subj, tls->hostname) <= 0))) {
mg_error(c, "failed to verify host");
return -1;
}
}
+16 -9
View File
@@ -1677,17 +1677,20 @@ static int mg_tls_verify_cert_san(const uint8_t *der, size_t dersz,
const char *server_name,
struct mg_addr *ref_ip) {
struct mg_der_tlv root, field, name;
int r;
bool is_addr = ref_ip != NULL;
if (mg_der_parse((uint8_t *) der, dersz, &root) < 0) {
MG_ERROR(("failed to parse certificate"));
return -1;
}
if (mg_der_find_oid(&root, (uint8_t *) "\x55\x1d\x11", 3, &field) <= 0) {
if ((r = mg_der_find_oid(&root, (uint8_t *) "\x55\x1d\x11", 3, &field)) < 0) {
MG_ERROR(("failed to extract SAN"));
return -1;
} else if (r == 0) {
return 0; // No SAN
}
if (mg_der_parse(field.value, field.len, &field) < 0) {
MG_ERROR(("SAN is not a constructed object"));
if (mg_der_parse(field.value, field.len, &field) < 0 || field.type != 0x30) {
MG_ERROR(("SAN is not a constructed object")); // RFC 5280 4.2.1.6
return -1;
}
while (mg_der_next(&field, &name) > 0) {
@@ -1714,6 +1717,7 @@ static int mg_tls_verify_cert_san(const uint8_t *der, size_t dersz,
return 1; // and matches the host name
}
}
MG_ERROR(("Found SAN but does not match IP or DNS name"));
return -1;
}
@@ -1901,12 +1905,15 @@ static int mg_tls_recv_cert(struct mg_connection *c, bool is_client) {
// and store public key for further CertVerify step
if (tls->hostname[0] != '\0') {
struct mg_addr addr; // use aton_ so localhost evals as a name
bool is_addr = mg_aton_(mg_str_s(tls->hostname), &addr);
if (mg_tls_verify_cert_san(cert, certsz, tls->hostname,
is_addr ? &addr : NULL) <= 0 &&
(is_addr || // IP references require a matching SAN
mg_tls_verify_cert_cn(&ci->subj, tls->hostname) <= 0)) {
mg_error(c, "failed to verify hostname");
bool is_addr;
int san;
is_addr = mg_aton_(mg_str_s(tls->hostname), &addr);
san = mg_tls_verify_cert_san(cert, certsz, tls->hostname,
is_addr ? &addr : NULL);
if (san < 0 || // RFC 6125 6.4.4 allow legacy fallback to CN
(san == 0 && (is_addr || mg_tls_verify_cert_cn(
&ci->subj, tls->hostname) <= 0))) {
mg_error(c, "failed to verify host");
return -1;
}
}