From 7401d5c1100a35dd5eafa602fad6d334dea98225 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Sat, 22 Mar 2014 14:23:33 +0100
Subject: [PATCH] add utilities for calculating http digest hashes

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 uclient-utils.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++
 uclient-utils.h | 14 ++++++++++
 2 files changed, 82 insertions(+)

diff --git a/uclient-utils.c b/uclient-utils.c
index 0d09974..66a4f15 100644
--- a/uclient-utils.c
+++ b/uclient-utils.c
@@ -1,7 +1,11 @@
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include <ctype.h>
 
+#include <libubox/md5.h>
+#include <libubox/utils.h>
+
 #include "uclient-utils.h"
 
 static const char *b64 =
@@ -75,3 +79,67 @@ int uclient_urldecode(const char *in, char *out, bool decode_plus)
 	*out = 0;
 	return ret;
 }
+
+static char hex_digit(char val)
+{
+	val += val > 9 ? 'a' - 10 : '0';
+	return val;
+}
+
+void bin_to_hex(char *dest, const void *buf, int len)
+{
+	const uint8_t *data = buf;
+	int i;
+
+	for (i = 0; i < len; i++) {
+		*(dest++) = hex_digit(data[i] >> 4);
+		*(dest++) = hex_digit(data[i] & 0xf);
+	}
+	*dest = 0;
+}
+
+static void http_create_hash(char *dest, const char * const * str, int n_str)
+{
+	uint32_t hash[4];
+	md5_ctx_t md5;
+	int i;
+
+	md5_begin(&md5);
+	for (i = 0; i < n_str; i++) {
+		if (i)
+			md5_hash(":", 1, &md5);
+		md5_hash(str[i], strlen(str[i]), &md5);
+	}
+	md5_end(hash, &md5);
+	bin_to_hex(dest, &hash, sizeof(hash));
+}
+
+void http_digest_calculate_auth_hash(char *dest, const char *user, const char *realm, const char *password)
+{
+	const char *hash_str[] = {
+		user,
+		realm,
+		password
+	};
+
+	http_create_hash(dest, hash_str, ARRAY_SIZE(hash_str));
+}
+
+void http_digest_calculate_response(char *dest, const struct http_digest_data *data)
+{
+	const char *h_a2_strings[] = {
+		data->method,
+		data->uri,
+	};
+	const char *resp_strings[] = {
+		data->auth_hash,
+		data->nonce,
+		data->nc,
+		data->cnonce,
+		data->qop,
+		dest, /* initialized to H(A2) first */
+	};
+
+	http_create_hash(dest, h_a2_strings, ARRAY_SIZE(h_a2_strings));
+	http_create_hash(dest, resp_strings, ARRAY_SIZE(resp_strings));
+}
diff --git a/uclient-utils.h b/uclient-utils.h
index a7eaf1c..83ab09a 100644
--- a/uclient-utils.h
+++ b/uclient-utils.h
@@ -3,14 +3,28 @@
 
 #include <stdbool.h>
 
+struct http_digest_data {
+	const char *uri;
+	const char *method;
+
+	const char *auth_hash; /* H(A1) */
+	const char *qop;
+	const char *nc;
+	const char *nonce;
+	const char *cnonce;
+};
+
 static inline int base64_len(int len)
 {
 	return ((len + 2) / 3) * 4;
 }
 
 void base64_encode(const void *inbuf, unsigned int len, void *out);
+void bin_to_hex(char *dest, const void *buf, int len);
 
 int uclient_urldecode(const char *in, char *out, bool decode_plus);
 
+void http_digest_calculate_auth_hash(char *dest, const char *user, const char *realm, const char *password);
+void http_digest_calculate_response(char *dest, const struct http_digest_data *data);
 
 #endif
-- 
2.25.1