✨ UserFilter for endpoints

include/user_filter.h

@@ -0,0 +1,18 @@
+#pragma once
+#include <drogon/HttpFilter.h>
+#include "bank.h"
+
+using namespace drogon;
+
+class UserFilter : public HttpFilter<UserFilter, false>
+{
+private:
+    Bank &bank;
+
+public:
+    UserFilter(Bank &);
+
+    virtual void doFilter(const HttpRequestPtr &,
+                          FilterCallback &&,
+                          FilterChainCallback &&) override;
+};

src/user_filter.cpp

@@ -0,0 +1,95 @@
+#include "user_filter.h"
+
+static char DecodeChar(const char ch)
+{
+    if (ch >= 'A' && ch <= 'Z')
+    {
+        return ch - 'A';
+    }
+    if (ch >= 'a' && ch <= 'z')
+    {
+        return ch - 'a' + 26;
+    }
+    if (ch >= '0' && ch <= '9')
+    {
+        return ch - '0' + 52;
+    }
+    return 63 - (ch == '-');
+}
+
+char *DecodeBase64(const char *string)
+{
+    char *output;
+    size_t length = strlen(string);
+    if (!(output = (char *)malloc(1 + (length >> 2) * 3 - (string[length - 1] == '=') - (string[length - 2] == '='))))
+    {
+        return (char *)0;
+    }
+
+    size_t index = 0;
+    uint32_t storage = 0;
+    while (string[4])
+    {
+        storage |= DecodeChar(*string++) << 18;
+        storage |= DecodeChar(*string++) << 12;
+        storage |= DecodeChar(*string++) << 6;
+        storage |= DecodeChar(*string++);
+
+        output[index++] = storage >> 16;
+        output[index++] = (char)(storage >> 8);
+        output[index++] = (char)storage;
+
+        storage = 0;
+    }
+
+    storage |= DecodeChar(*string++) << 18;
+    storage |= DecodeChar(*string++) << 12;
+    output[index++] = storage >> 16;
+
+    if (*string == '=')
+    {
+        output[index] = '\0';
+        return output;
+    }
+    storage |= DecodeChar(*string++) << 6;
+    output[index++] = (char)(storage >> 8);
+
+    if (*string == '=')
+    {
+        output[index] = '\0';
+        return output;
+    }
+    storage |= DecodeChar(*string);
+    output[index++] = (char)storage;
+
+    output[index] = '\0';
+    return output;
+}
+
+UserFilter::UserFilter(Bank &b) : bank(b) {}
+
+void UserFilter::doFilter(const HttpRequestPtr &req,
+                          FilterCallback &&fcb,
+                          FilterChainCallback &&fccb)
+{
+    const std::string &auth_header = req->getHeader("Authorization");
+    if (auth_header.size() > 6)
+    {
+        if (auth_header.substr(0, 6) == "Basic ")
+        {
+            std::stringstream ss(DecodeBase64(auth_header.substr(6).c_str()));
+            std::string username, password;
+            std::getline(ss, username, ':');
+            std::getline(ss, password);
+            if (bank.VerifyPassword(username, password))
+            {
+                req->setParameter("name", username);
+                fccb();
+                return;
+            }
+        }
+    }
+    auto resp = HttpResponse::newHttpJsonResponse("Invalid Credentials");
+    resp->setStatusCode(k401Unauthorized);
+    fcb(resp);
+}