From: Tollef Fog Heen <tfheen@err.no>
Date: Mon, 12 Oct 2009 09:13:58 +0000 (+0200)
Subject: Validate h if it exists in the request
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=278a2fe315eff41a809d6fc473203261fe483b61;p=yubikey-server-c

Validate h if it exists in the request
---

diff --git a/src/main.c b/src/main.c
index ec83558..05d037f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -62,6 +62,42 @@ char *get_timestamp(void) {
 	return ts;
 }
 
+int validate_signature(const char *key, size_t key_len, const char *h,
+		       const char *id, const char *otp)
+{
+	char *line = NULL;
+	char *our_sig = NULL;
+	gcry_md_hd_t hd;
+	int r = 0;
+	asprintf(&line, "i=%s&otp=%s", id, otp);
+	if (line == NULL) {
+		r = -1;
+		goto free_mem;
+	}
+	gcry_md_open(&hd, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC);
+	if (hd == NULL) {
+		r = -1;
+		goto free_mem;
+	}
+
+	gcry_md_setkey(hd, key, key_len);
+	gcry_md_write(hd, line, strlen(line));
+	gcry_md_final(hd);
+	our_sig = ysc_b64_encode((char *) gcry_md_read(hd, 0),
+				 gcry_md_get_algo_dlen(GCRY_MD_SHA1));
+	if (our_sig == NULL || strcmp(our_sig, h) != 0) {
+		r = -1;
+		goto free_mem;
+	}
+
+free_mem:
+	gcry_md_close(hd);
+	free(line);
+	free(our_sig);
+
+	return r;
+}
+
 char *sign_request(char *key, size_t key_len, char *info, char *status,
 		   char *timestamp) {
 	char *line;
@@ -345,7 +381,16 @@ static int handle_request(void * UNUSED(data),
 		goto free_mem;
 	}
 
-	/* XXX: If h exists, verify. FIXME */
+	if (h != NULL) {
+		if (validate_signature(shared_secret, shared_secret_len, h, 
+				       id, otp) < 0) {
+		status = "BAD_SIGNATURE";
+		signature = sign_request(shared_secret, shared_secret_len,
+					 NULL, status, timestamp);
+		send_response(conn, signature, status, NULL, timestamp);
+		goto free_mem;
+		}
+	}
 
 	/* Validate OTP */
 	/* Find public uid, if possible */