1 files changed, 181 insertions, 0 deletions
diff --git a/web/server/h2o/libh2o/deps/ssl-conservatory/openssl/openssl_hostname_validation.c b/web/server/h2o/libh2o/deps/ssl-conservatory/openssl/openssl_hostname_validation.c
new file mode 100644
index 00000000..066fd6dd
--- /dev/null
+++ b/web/server/h2o/libh2o/deps/ssl-conservatory/openssl/openssl_hostname_validation.c
@@ -0,0 +1,181 @@
+/*
+ * Helper functions to perform basic hostname validation using OpenSSL.
+ *
+ * Please read "everything-you-wanted-to-know-about-openssl.pdf" before
+ * attempting to use this code. This whitepaper describes how the code works, 
+ * how it should be used, and what its limitations are.
+ *
+ * Author:  Alban Diquet
+ * License: See LICENSE
+ *
+ */
+ 
+
+#include <strings.h>
+#include <openssl/x509v3.h>
+#include <openssl/ssl.h>
+
+#include "openssl_hostname_validation.h"
+
+
+#define HOSTNAME_MAX_SIZE 255
+
+static int lowercase(int ch) {
+	if ('A' <= ch && ch <= 'Z')
+		return ch - 'A' + 'a';
+	return ch;
+}
+
+static int memeq_ncase(const char *x, const char *y, size_t l) {
+	if (l == 0)
+		return 1;
+	do {
+		if (lowercase(*x++) != lowercase(*y++))
+			return 0;
+	} while (--l != 0);
+	return 1;
+}
+
+static int has_nul(const char *s, size_t l) {
+	if (l == 0)
+		return 0;
+	do {
+		if (*s++ == '\0')
+			return 1;
+	} while (--l != 0);
+	return 0;
+}
+
+static HostnameValidationResult validate_name(const char *hostname, ASN1_STRING *certname_asn1) {
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L) && !defined(LIBRESSL_VERSION_NUMBER)
+	char *certname_s = (char *) ASN1_STRING_get0_data(certname_asn1);
+#else
+	char *certname_s = (char *) ASN1_STRING_data(certname_asn1);
+#endif
+	int certname_len = ASN1_STRING_length(certname_asn1), hostname_len = strlen(hostname);
+
+	// Make sure there isn't an embedded NUL character in the DNS name
+	if (has_nul(certname_s, certname_len)) {
+		return MalformedCertificate;
+	}
+	// remove last '.' from hostname
+	if (hostname_len != 0 && hostname[hostname_len - 1] == '.')
+		--hostname_len;
+	// skip the first segment if wildcard
+	if (certname_len > 2 && certname_s[0] == '*' && certname_s[1] == '.') {
+		if (hostname_len != 0) {
+			do {
+				--hostname_len;
+				if (*hostname++ == '.')
+					break;
+			} while (hostname_len != 0);
+		}
+		certname_s += 2;
+		certname_len -= 2;
+	}
+	// Compare expected hostname with the DNS name
+	if (certname_len != hostname_len) {
+		return MatchNotFound;
+	}
+	return memeq_ncase(hostname, certname_s, hostname_len) ? MatchFound : MatchNotFound;
+}
+
+/**
+* Tries to find a match for hostname in the certificate's Common Name field.
+*
+* Returns MatchFound if a match was found.
+* Returns MatchNotFound if no matches were found.
+* Returns MalformedCertificate if the Common Name had a NUL character embedded in it.
+* Returns Error if the Common Name could not be extracted.
+*/
+static HostnameValidationResult matches_common_name(const char *hostname, const X509 *server_cert) {
+	int common_name_loc = -1;
+	X509_NAME_ENTRY *common_name_entry = NULL;
+	ASN1_STRING *common_name_asn1 = NULL;
+
+	// Find the position of the CN field in the Subject field of the certificate
+	common_name_loc = X509_NAME_get_index_by_NID(X509_get_subject_name((X509 *) server_cert), NID_commonName, -1);
+	if (common_name_loc < 0) {
+		return Error;
+	}
+
+	// Extract the CN field
+	common_name_entry = X509_NAME_get_entry(X509_get_subject_name((X509 *) server_cert), common_name_loc);
+	if (common_name_entry == NULL) {
+		return Error;
+	}
+	common_name_asn1 = X509_NAME_ENTRY_get_data(common_name_entry);
+	if (common_name_asn1 == NULL) {
+		return Error;
+	}
+
+	// validate the names
+	return validate_name(hostname, common_name_asn1);
+}
+
+
+/**
+* Tries to find a match for hostname in the certificate's Subject Alternative Name extension.
+*
+* Returns MatchFound if a match was found.
+* Returns MatchNotFound if no matches were found.
+* Returns MalformedCertificate if any of the hostnames had a NUL character embedded in it.
+* Returns NoSANPresent if the SAN extension was not present in the certificate.
+*/
+static HostnameValidationResult matches_subject_alternative_name(const char *hostname, const X509 *server_cert) {
+	HostnameValidationResult result = MatchNotFound;
+	int i;
+	int san_names_nb = -1;
+	STACK_OF(GENERAL_NAME) *san_names = NULL;
+
+	// Try to extract the names within the SAN extension from the certificate
+	san_names = X509_get_ext_d2i((X509 *) server_cert, NID_subject_alt_name, NULL, NULL);
+	if (san_names == NULL) {
+		return NoSANPresent;
+	}
+	san_names_nb = sk_GENERAL_NAME_num(san_names);
+
+	// Check each name within the extension
+	for (i=0; i<san_names_nb; i++) {
+		const GENERAL_NAME *current_name = sk_GENERAL_NAME_value(san_names, i);
+
+		if (current_name->type == GEN_DNS) {
+			// Current name is a DNS name, let's check it
+			result = validate_name(hostname, current_name->d.dNSName);
+			if (result != MatchNotFound) {
+				break;
+			}
+		}
+	}
+	sk_GENERAL_NAME_pop_free(san_names, GENERAL_NAME_free);
+
+	return result;
+}
+
+
+/**
+* Validates the server's identity by looking for the expected hostname in the
+* server's certificate. As described in RFC 6125, it first tries to find a match
+* in the Subject Alternative Name extension. If the extension is not present in
+* the certificate, it checks the Common Name instead.
+*
+* Returns MatchFound if a match was found.
+* Returns MatchNotFound if no matches were found.
+* Returns MalformedCertificate if any of the hostnames had a NUL character embedded in it.
+* Returns Error if there was an error.
+*/
+HostnameValidationResult validate_hostname(const char *hostname, const X509 *server_cert) {
+	HostnameValidationResult result;
+
+	if((hostname == NULL) || (server_cert == NULL))
+		return Error;
+
+	// First try the Subject Alternative Names extension
+	result = matches_subject_alternative_name(hostname, server_cert);
+	if (result == NoSANPresent) {
+		// Extension was not found: try the Common Name
+		result = matches_common_name(hostname, server_cert);
+	}
+
+	return result;
+}