From c607ba05a99e4542ac8781039079a04dda8d5432 Mon Sep 17 00:00:00 2001
From: Jordan Bancino <jordan@bancino.net>
Date: Tue, 6 Sep 2022 20:48:27 -0400
Subject: [PATCH] Implement URL encoding and decoding.

---
 site/index.html    |   2 +-
 src/Http.c         | 149 +++++++++++++++++++++++++++++++++++++++++++++
 src/HttpServer.c   |   2 +-
 src/include/Http.h |   6 ++
 4 files changed, 157 insertions(+), 2 deletions(-)

diff --git a/site/index.html b/site/index.html
index 4dea0de..2b19411 100644
--- a/site/index.html
+++ b/site/index.html
@@ -494,7 +494,7 @@ can get involved.
 <li><s>Implement a simple HTTP server</s>
 <ul>
 <li>Implement param parser</li>
-<li>Properly decode paths</li>
+<li><s>URL encoder/decoder</s></li>
 </ul>
 </li>
 <li>
diff --git a/src/Http.c b/src/Http.c
index c0c49f2..4b9db64 100644
--- a/src/Http.c
+++ b/src/Http.c
@@ -23,6 +23,8 @@
  */
 #include <Http.h>
 
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 const char *
@@ -211,3 +213,150 @@ HttpStatusToString(const HttpStatus status)
             return NULL;
     }
 }
+
+char *
+HttpUrlEncode(char *str)
+{
+    size_t size;
+    size_t len;
+    char *encoded;
+
+    if (!str)
+    {
+        return NULL;
+    }
+
+    size = 16;
+    len = 0;
+    encoded = malloc(size);
+    if (!encoded)
+    {
+        return NULL;
+    }
+
+    while (*str)
+    {
+        char c = *str;
+
+        if (len >= size - 4)
+        {
+            char *tmp;
+
+            size *= 2;
+            tmp = realloc(encoded, size);
+            if (!tmp)
+            {
+                free(encoded);
+                return NULL;
+            }
+
+            encoded = tmp;
+        }
+
+        /* Control characters and extended characters */
+        if (c <= 0x1F || c >= 0x7F)
+        {
+            goto percentEncode;
+        }
+
+        /* Reserved and unsafe characters */
+        switch (c)
+        {
+            case '$':
+            case '&':
+            case '+':
+            case ',':
+            case '/':
+            case ':':
+            case ';':
+            case '=':
+            case '?':
+            case '@':
+            case ' ':
+            case '"':
+            case '<':
+            case '>':
+            case '#':
+            case '%':
+            case '{':
+            case '}':
+            case '|':
+            case '\\':
+            case '^':
+            case '~':
+            case '[':
+            case ']':
+            case '`':
+                goto percentEncode;
+                break;
+            default:
+                encoded[len] = c;
+                len++;
+                str++;
+                continue;
+        }
+
+percentEncode:
+        encoded[len] = '%';
+        len++;
+        snprintf(encoded + len, 3, "%2X", c);
+        len += 2;
+
+        str++;
+    }
+
+    encoded[len] = '\0';
+    return encoded;
+}
+
+char *
+HttpUrlDecode(char *str)
+{
+    size_t i;
+    size_t inputLen;
+    char *decoded;
+
+    if (!str)
+    {
+        return NULL;
+    }
+
+    i = 0;
+    inputLen = strlen(str);
+    decoded = malloc(inputLen);
+
+    if (!decoded)
+    {
+        return NULL;
+    }
+
+    while (*str)
+    {
+        char c = *str;
+
+        if (c == '%')
+        {
+            if (sscanf(str + 1, "%2X", (unsigned int *) &c) != 1)
+            {
+                /* Decoding error */
+                free(decoded);
+                return NULL;
+            }
+            str += 2;
+
+            if (!c)
+            {
+                /* Null character given, don't put that in the string. */
+                str++;
+                continue;
+            }
+        }
+
+        decoded[i] = c;
+        i++;
+
+        str++;
+    }
+
+    return decoded;
+}
diff --git a/src/HttpServer.c b/src/HttpServer.c
index b9dc91b..9024be6 100644
--- a/src/HttpServer.c
+++ b/src/HttpServer.c
@@ -102,7 +102,7 @@ HttpServerContextCreate(HttpRequestMethod requestMethod,
     c->requestMethod = requestMethod;
     c->requestPath = requestPath;
     c->stream = stream;
-	c->responseStatus = HTTP_OK;
+    c->responseStatus = HTTP_OK;
 
     return c;
 }
diff --git a/src/include/Http.h b/src/include/Http.h
index ae71399..5a6a607 100644
--- a/src/include/Http.h
+++ b/src/include/Http.h
@@ -109,4 +109,10 @@ extern HttpRequestMethod
 extern const char *
  HttpRequestMethodToString(const HttpRequestMethod);
 
+extern char *
+ HttpUrlEncode(char *);
+
+extern char *
+ HttpUrlDecode(char *);
+
 #endif