Handle Sec-WebSocket-Accept correctly

ixwebsocket/IXWebSocketTransport.cpp

@@ -19,6 +19,8 @@
 # endif
 #endif
 
+#include "libwshandshake.hpp"
+
 // #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
@@ -30,6 +32,8 @@
 #include <iostream>
 #include <sstream>
 #include <regex>
+#include <unordered_map>
+#include <random>
 
 
 namespace ix {
@@ -128,6 +132,28 @@ namespace ix {
         std::cout << "-------------------------------" << std::endl;
     }
 
+    std::string WebSocketTransport::genRandomString(const int len)
+    {
+        static const char alphanum[] =
+            "0123456789"
+            "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+            "abcdefghijklmnopqrstuvwxyz";
+
+        std::random_device r;
+        std::default_random_engine e1(r());
+        std::uniform_int_distribution<int> dist(0, sizeof(alphanum) - 1);
+
+        std::string s;
+        s.resize(len);
+
+        for (int i = 0; i < len; ++i)
+        {
+            s[i] += alphanum[dist(e1)];
+        }
+
+        return s;
+    }
+
     WebSocketInitResult WebSocketTransport::init()
     {
         std::string protocol, host, path, query;
@@ -169,6 +195,16 @@ namespace ix {
             return WebSocketInitResult(false, 0, ss.str());
         }
 
+        //
+        // Generate a random 24 bytes string which looks like it is base64 encoded
+        // y3JJHMbDL1EzLkh9GBhXDw==
+        // 0cb3Vd9HkbpVVumoS3Noka==
+        //
+        // See https://stackoverflow.com/questions/18265128/what-is-sec-websocket-key-for
+        //
+        std::string secWebSocketKey = genRandomString(22);
+        secWebSocketKey += "==";
+
         char line[256];
         int status;
         int i;
@@ -177,12 +213,10 @@ namespace ix {
             "Host: %s:%d\r\n"
             "Upgrade: websocket\r\n"
             "Connection: Upgrade\r\n"
-            "Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==\r\n"
+            "Sec-WebSocket-Key: %s\r\n"
             "Sec-WebSocket-Version: 13\r\n"
             "\r\n",
-            path.c_str(), host.c_str(), port);
+            path.c_str(), host.c_str(), port, secWebSocketKey.c_str());
-
-        // XXX: this should be done non-blocking,
 
         size_t lineSize = strlen(line);
         if (_socket->send(line, lineSize) != lineSize)
@@ -224,9 +258,12 @@ namespace ix {
             return WebSocketInitResult(false, status, ss.str());
         }
 
-        // TODO: verify response headers,
+        std::unordered_map<std::string, std::string> headers;
+
         while (true) 
         {
+            int colon = 0;
+
             for (i = 0;
                  i < 2 || (i < 255 && line[i-2] != '\r' && line[i-1] != '\n');
                  ++i)
@@ -235,11 +272,38 @@ namespace ix {
                 {
                     return WebSocketInitResult(false, status, std::string("Failed reading response header from ") + _url);
                 }
+
+                if (line[i] == ':' && colon == 0)
+                {
+                    colon = i;
+                }
             }
             if (line[0] == '\r' && line[1] == '\n')
             {
                 break;
             }
+
+            // line is a single header entry. split by ':', and add it to our
+            // header map. ignore lines with no colon.
+            if (colon > 0)
+            {
+                line[i] = '\0';
+                std::string lineStr(line);
+                // colon is ':', colon+1 is ' ', colon+2 is the start of the value.
+                // i is end of string (\0), i-colon is length of string minus key;
+                // subtract 1 for '\0', 1 for '\n', 1 for '\r',
+                // 1 for the ' ' after the ':', and total is -4
+                headers[lineStr.substr(0, colon)] =
+                    lineStr.substr(colon + 2, i - colon - 4);
+            }
+        }
+
+        char output[29] = {};
+        WebSocketHandshake::generate(secWebSocketKey.c_str(), output);
+        if (std::string(output) != headers["Sec-WebSocket-Accept"])
+        {
+            std::string errorMsg("Invalid Sec-WebSocket-Accept value");
+            return WebSocketInitResult(false, status, errorMsg);
         }
 
         _socket->configure();

ixwebsocket/IXWebSocketTransport.h

@@ -142,5 +142,6 @@ namespace ix
 
         unsigned getRandomUnsigned();
         void unmaskReceiveBuffer(const wsheader_type& ws);
+        std::string genRandomString(const int len);
     };
 }

ixwebsocket/libwshandshake.hpp

@@ -0,0 +1,128 @@
+// Copyright (c) 2016 Alex Hultman and contributors
+
+// This software is provided 'as-is', without any express or implied
+// warranty. In no event will the authors be held liable for any damages
+// arising from the use of this software.
+
+// Permission is granted to anyone to use this software for any purpose,
+// including commercial applications, and to alter it and redistribute it
+// freely, subject to the following restrictions:
+
+// 1. The origin of this software must not be misrepresented; you must not
+//    claim that you wrote the original software. If you use this software
+//    in a product, an acknowledgement in the product documentation would be
+//    appreciated but is not required.
+// 2. Altered source versions must be plainly marked as such, and must not be
+//    misrepresented as being the original software.
+// 3. This notice may not be removed or altered from any source distribution.
+
+#pragma once
+
+#include <cstdint>
+#include <cstddef>
+
+class WebSocketHandshake {
+    template <int N, typename T>
+    struct static_for {
+        void operator()(uint32_t *a, uint32_t *b) {
+            static_for<N - 1, T>()(a, b);
+            T::template f<N - 1>(a, b);
+        }
+    };
+
+    template <typename T>
+    struct static_for<0, T> {
+        void operator()(uint32_t *a, uint32_t *hash) {}
+    };
+
+    template <int state>
+    struct Sha1Loop {
+        static inline uint32_t rol(uint32_t value, size_t bits) {return (value << bits) | (value >> (32 - bits));}
+        static inline uint32_t blk(uint32_t b[16], size_t i) {
+            return rol(b[(i + 13) & 15] ^ b[(i + 8) & 15] ^ b[(i + 2) & 15] ^ b[i], 1);
+        }
+
+        template <int i>
+        static inline void f(uint32_t *a, uint32_t *b) {
+            switch (state) {
+            case 1:
+                a[i % 5] += ((a[(3 + i) % 5] & (a[(2 + i) % 5] ^ a[(1 + i) % 5])) ^ a[(1 + i) % 5]) + b[i] + 0x5a827999 + rol(a[(4 + i) % 5], 5);
+                a[(3 + i) % 5] = rol(a[(3 + i) % 5], 30);
+                break;
+            case 2:
+                b[i] = blk(b, i);
+                a[(1 + i) % 5] += ((a[(4 + i) % 5] & (a[(3 + i) % 5] ^ a[(2 + i) % 5])) ^ a[(2 + i) % 5]) + b[i] + 0x5a827999 + rol(a[(5 + i) % 5], 5);
+                a[(4 + i) % 5] = rol(a[(4 + i) % 5], 30);
+                break;
+            case 3:
+                b[(i + 4) % 16] = blk(b, (i + 4) % 16);
+                a[i % 5] += (a[(3 + i) % 5] ^ a[(2 + i) % 5] ^ a[(1 + i) % 5]) + b[(i + 4) % 16] + 0x6ed9eba1 + rol(a[(4 + i) % 5], 5);
+                a[(3 + i) % 5] = rol(a[(3 + i) % 5], 30);
+                break;
+            case 4:
+                b[(i + 8) % 16] = blk(b, (i + 8) % 16);
+                a[i % 5] += (((a[(3 + i) % 5] | a[(2 + i) % 5]) & a[(1 + i) % 5]) | (a[(3 + i) % 5] & a[(2 + i) % 5])) + b[(i + 8) % 16] + 0x8f1bbcdc + rol(a[(4 + i) % 5], 5);
+                a[(3 + i) % 5] = rol(a[(3 + i) % 5], 30);
+                break;
+            case 5:
+                b[(i + 12) % 16] = blk(b, (i + 12) % 16);
+                a[i % 5] += (a[(3 + i) % 5] ^ a[(2 + i) % 5] ^ a[(1 + i) % 5]) + b[(i + 12) % 16] + 0xca62c1d6 + rol(a[(4 + i) % 5], 5);
+                a[(3 + i) % 5] = rol(a[(3 + i) % 5], 30);
+                break;
+            case 6:
+                b[i] += a[4 - i];
+            }
+        }
+    };
+
+    static inline void sha1(uint32_t hash[5], uint32_t b[16]) {
+        uint32_t a[5] = {hash[4], hash[3], hash[2], hash[1], hash[0]};
+        static_for<16, Sha1Loop<1>>()(a, b);
+        static_for<4, Sha1Loop<2>>()(a, b);
+        static_for<20, Sha1Loop<3>>()(a, b);
+        static_for<20, Sha1Loop<4>>()(a, b);
+        static_for<20, Sha1Loop<5>>()(a, b);
+        static_for<5, Sha1Loop<6>>()(a, hash);
+    }
+
+    static inline void base64(unsigned char *src, char *dst) {
+        const char *b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+        for (int i = 0; i < 18; i += 3) {
+            *dst++ = b64[(src[i] >> 2) & 63];
+            *dst++ = b64[((src[i] & 3) << 4) | ((src[i + 1] & 240) >> 4)];
+            *dst++ = b64[((src[i + 1] & 15) << 2) | ((src[i + 2] & 192) >> 6)];
+            *dst++ = b64[src[i + 2] & 63];
+        }
+        *dst++ = b64[(src[18] >> 2) & 63];
+        *dst++ = b64[((src[18] & 3) << 4) | ((src[19] & 240) >> 4)];
+        *dst++ = b64[((src[19] & 15) << 2)];
+        *dst++ = '=';
+    }
+
+public:
+    static inline void generate(const char input[24], char output[28]) {
+        uint32_t b_output[5] = {
+            0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0
+        };
+        uint32_t b_input[16] = {
+            0, 0, 0, 0, 0, 0, 0x32353845, 0x41464135, 0x2d453931, 0x342d3437, 0x44412d39,
+            0x3543412d, 0x43354142, 0x30444338, 0x35423131, 0x80000000
+        };
+
+        for (int i = 0; i < 6; i++) {
+            b_input[i] = (input[4 * i + 3] & 0xff) | (input[4 * i + 2] & 0xff) << 8 | (input[4 * i + 1] & 0xff) << 16 | (input[4 * i + 0] & 0xff) << 24;
+        }
+        sha1(b_output, b_input);
+        uint32_t last_b[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 480};
+        sha1(b_output, last_b);
+        for (int i = 0; i < 5; i++) {
+            uint32_t tmp = b_output[i];
+            char *bytes = (char *) &b_output[i];
+            bytes[3] = tmp & 0xff;
+            bytes[2] = (tmp >> 8) & 0xff;
+            bytes[1] = (tmp >> 16) & 0xff;
+            bytes[0] = (tmp >> 24) & 0xff;
+        }
+        base64((unsigned char *) b_output, output);
+    }
+};