stun

commit b59586b4ba0af5a83f144466a9fa1d72ff2d2006
parent 9f259643eb44104b25a0c5039466d9938f618fb3
Author: sin <sin@2f30.org>
Date:   Tue, 29 Mar 2016 19:19:18 +0100

clean up crypto code

Diffstat:
M
stun.c
 | 
78
+++++++++++++++++++++++++++++++++++++++++-------------------------------------

1 file changed, 41 insertions(+), 37 deletions(-)
diff --git a/stun.c b/stun.c
@@ -27,7 +27,7 @@
  * All tunneled traffic is encapsulated inside the TCP payload.
  * The packet format is shown below:
  *
- * [PAYLOAD LENGTH][PAYLOAD]
+ * [UNPADDED PAYLOAD LENGTH][PADDED PAYLOAD]
  *
  * The payload is encrypted and padded to 16 bytes.  The payload length is a
  * two-octet field that describes the length of the unpadded payload.
@@ -197,10 +197,13 @@ int
 aesinit(EVP_CIPHER_CTX *ectx, EVP_CIPHER_CTX *dctx)
 {
 	EVP_CIPHER_CTX_init(ectx);
-	EVP_CIPHER_CTX_init(dctx);
+	EVP_EncryptInit_ex(ectx, EVP_aes_256_cbc(), NULL, NULL, NULL);
 	EVP_EncryptInit_ex(ectx, EVP_aes_256_cbc(), NULL, aeskey, aesiv);
-	EVP_DecryptInit_ex(dctx, EVP_aes_256_cbc(), NULL, aeskey, aesiv);
 	EVP_CIPHER_CTX_set_padding(ectx, 0);
+
+	EVP_CIPHER_CTX_init(dctx);
+	EVP_DecryptInit_ex(dctx, EVP_aes_256_cbc(), NULL, NULL, NULL);
+	EVP_DecryptInit_ex(dctx, EVP_aes_256_cbc(), NULL, aeskey, aesiv);
 	EVP_CIPHER_CTX_set_padding(dctx, 0);
 	return 0;
 }
@@ -213,23 +216,21 @@ aesterm(EVP_CIPHER_CTX *ectx, EVP_CIPHER_CTX *dctx)
 }
 
 int
-aesenc(EVP_CIPHER_CTX *ectx, unsigned char *ciphertext,
-       unsigned char *plaintext, int len)
+aesenc(EVP_CIPHER_CTX *ctx, unsigned char *ct, unsigned char *pt, int plen)
 {
 	int clen;
 
-	if (EVP_EncryptUpdate(ectx, ciphertext, &clen, plaintext, len) != 1)
+	if (EVP_EncryptUpdate(ctx, ct, &clen, pt, plen) != 1)
 		logerr("EVP_EncryptUpdate failed");
 	return clen;
 }
 
 int
-aesdec(EVP_CIPHER_CTX *dctx, unsigned char *plaintext,
-       unsigned char *ciphertext, int len)
+aesdec(EVP_CIPHER_CTX *ctx, unsigned char *pt, unsigned char *ct, int clen)
 {
 	int plen;
 
-	if (EVP_DecryptUpdate(dctx, plaintext, &plen, ciphertext, len) != 1)
+	if (EVP_DecryptUpdate(ctx, pt, &plen, ct, clen) != 1)
 		logerr("EVP_DecryptUpdate failed");
 	return plen;
 }
@@ -427,24 +428,6 @@ writeall(int fd, void *buf, int len)
 }
 
 int
-writenet(int fd, unsigned char *buf, int len)
-{
-	unsigned char encbuf[MTU + AES_BLOCK_SIZE + HDRLEN];
-
-	/* fill padding with random bytes */
-	if (padlen(len, AES_BLOCK_SIZE) > 0)
-		arc4random_buf(&encbuf[HDRLEN + len],
-	                       padlen(len, AES_BLOCK_SIZE));
-
-	aesenc(&enc, &encbuf[HDRLEN], buf, padto(len, AES_BLOCK_SIZE));
-	/* insert unpadded payload len at the start of the packet */
-	pack16(encbuf, len);
-	/* calculate total size of packet and send it on the wire */
-	len = padto(len, AES_BLOCK_SIZE) + HDRLEN;
-	return writeall(fd, encbuf, len);
-}
-
-int
 readall(int fd, void *buf, int len)
 {
 	unsigned char *p = buf;
@@ -466,28 +449,49 @@ readall(int fd, void *buf, int len)
 }
 
 int
-readnet(int fd, unsigned char *buf, int len)
+writenet(int fd, unsigned char *pt, int len)
+{
+	unsigned char payload[MTU + AES_BLOCK_SIZE];
+	unsigned char hdr[HDRLEN];
+	unsigned char pkt[sizeof(hdr) + sizeof(payload)];
+
+	/* fill padding with random bytes */
+	if (padlen(len, AES_BLOCK_SIZE) > 0)
+		arc4random_buf(&payload[len], padlen(len, AES_BLOCK_SIZE));
+
+	pack16(hdr, len);
+	len = padto(len, AES_BLOCK_SIZE);
+	aesenc(&enc, payload, pt, len);
+	memcpy(pkt, hdr, HDRLEN);
+	memcpy(&pkt[HDRLEN], payload, len);
+	len += HDRLEN;
+	return writeall(fd, pkt, len);
+}
+
+int
+readnet(int fd, unsigned char *pt, int len)
 {
-	unsigned char encbuf[MTU + AES_BLOCK_SIZE + HDRLEN];
+	unsigned char payload[MTU + AES_BLOCK_SIZE];
+	unsigned char hdr[HDRLEN];
 	int n, pktlen, paddedlen;
 
 	/* read unpadded packet length */
-	n = readall(fd, encbuf, HDRLEN);
+	n = readall(fd, hdr, HDRLEN);
 	if (n <= 0)
 		return n;
 
-	pktlen = unpack16(encbuf);
+	pktlen = unpack16(hdr);
 	pktlen &= PKTLENMASK;
 	paddedlen = padto(pktlen, AES_BLOCK_SIZE);
 
 	/* discard bad packets */
-	if (pktlen > len || paddedlen > MTU + AES_BLOCK_SIZE) {
+	if (pktlen > len || paddedlen > sizeof(payload)) {
 		while (paddedlen) {
-			if (paddedlen > MTU + AES_BLOCK_SIZE)
-				len = MTU + AES_BLOCK_SIZE;
+			if (paddedlen > sizeof(payload))
+				len = sizeof(payload);
 			else
 				len = paddedlen;
-			n = readall(fd, encbuf, len);
+			n = readall(fd, payload, len);
 			if (n <= 0)
 				break;
 			paddedlen -= n;
@@ -496,11 +500,11 @@ readnet(int fd, unsigned char *buf, int len)
 	}
 
 	/* read encrypted payload */
-	n = readall(fd, &encbuf[HDRLEN], paddedlen);
+	n = readall(fd, payload, paddedlen);
 	if (n <= 0)
 		return n;
 
-	aesdec(&dec, buf, &encbuf[HDRLEN], paddedlen);
+	aesdec(&dec, pt, payload, paddedlen);
 	return pktlen;
 }