From 88081d9a4376b1ee4feed3bc843c46096e087b1e Mon Sep 17 00:00:00 2001
From: Aleksey Veresov <aleksey@veresov.pro>
Date: Fri, 22 Nov 2019 18:55:54 +0300
Subject: .

---
 src/urlenc.c | 187 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 187 insertions(+)
 create mode 100644 src/urlenc.c

(limited to 'src/urlenc.c')

diff --git a/src/urlenc.c b/src/urlenc.c
new file mode 100644
index 0000000..336dde0
--- /dev/null
+++ b/src/urlenc.c
@@ -0,0 +1,187 @@
+#include "urlencoded.h"
+
+#include "error.h"
+#include "field.h"
+#include <ctype.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Local Shortcuts
+ */
+/* Shouldn't be called with 'c' as not hex digit. */
+static char from_hex(char c)
+{
+    char num;
+    if (isdigit(c)) {
+        num = c - '0';
+    } else {
+        num = toupper(c) - 'A' + 10;
+    }
+    return num;
+}
+
+static int is_hex(char c)
+{
+    return isdigit(c) || strchr("ABCDEF", toupper(c));
+}
+
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * URL Decoding
+ */
+static int deurl(char ** data)
+{
+    int ok = 1;
+    if (*data) {
+        char * val = *data;
+        int    ti  = 0;
+        int    ci;
+        for (ci = 0; ok && val[ci]; ++ti, ++ci) {
+            if (val[ci] == '%') {
+                if (is_hex(val[ci + 1]) && is_hex(val[ci + 2])) {
+                    /* Since chars can be signed, arithmetics are not safe. */
+                    val[ti] = from_hex(val[ci + 2]);       /* 00xx */
+                    val[ti] |= from_hex(val[ci + 1]) << 4; /* XXxx */
+                    ci += 2;
+                } else {
+                    ok = 0;
+                    magi_error_set(
+                        "[urlencoded] Waiting for two hex digits after '%%', "
+                        "readed: \\%o\\%o (render: %c%c)",
+                        val[ci + 1], val[ci + 2], val[ci + 1], val[ci + 2]);
+                }
+            } else if (val[ci] == '+') {
+                val[ti] = ' ';
+            } else {
+                val[ti] = val[ci];
+            }
+        }
+        val[ti++] = 0;
+    } else {
+        *data  = malloc(1);
+        **data = 0;
+    }
+    return ok;
+}
+
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Urlencoded Automata
+ */
+enum st { st_error = 0, st_name, st_data };
+
+struct automata {
+    struct magi_field_list ** list;
+    struct magi_field         field;
+    int                       size;
+    int                       len;
+};
+
+
+static enum st parse_name(struct automata * a, char c)
+{
+    enum st state;
+    if (c != '&' && c != ';') {
+        if (c == '=') {
+            state   = st_data;
+            a->size = 1;
+            a->len  = 0;
+        } else {
+            if (a->len == a->size - 1) {
+                a->size *= 2;
+                a->field.name = realloc(a->field.name, a->size);
+            }
+            if (!a->field.name) {
+                state = st_error;
+                magi_error_set("[urlencoded] Cannot allocate field name.");
+            } else {
+                state = st_name;
+                a->len++;
+                a->field.name[a->len - 1] = c;
+                a->field.name[a->len]     = 0;
+            }
+        }
+    } else {
+        state = st_error;
+        magi_error_set("[urlencoded] Reading name, readed: \\%o (render: %c).",
+                       c, c);
+    }
+    return state;
+}
+
+static enum st end_data(struct automata * a)
+{
+    enum st state = st_error;
+    if (deurl(&a->field.name) && deurl(&a->field.data)) {
+        a->field.len = strlen(a->field.data);
+        if (magi_field_list_add(a->list, &a->field)) {
+            state         = st_name;
+            a->size       = 1;
+            a->len        = 0;
+            a->field.name = 0;
+            a->field.data = 0;
+        }
+    }
+    return state;
+}
+
+static enum st parse_data(struct automata * a, char c)
+{
+    enum st state;
+    if (c != '=') {
+        if (c == '&' || c == ';') {
+            state = end_data(a);
+        } else {
+            if (a->len == a->size - 1) {
+                a->size *= 2;
+                a->field.data = realloc(a->field.data, a->size);
+            }
+            if (!a->field.data) {
+                state = st_error;
+                magi_error_set("[urlencoded] Cannot allocate field data.");
+            } else {
+                state = st_data;
+                a->len++;
+                a->field.data[a->len - 1] = c;
+                a->field.data[a->len]     = 0;
+            }
+        }
+    } else {
+        state = st_error;
+        magi_error_set("[urlencoded] Reading data, readed: \\%o (render: %c).",
+                       c, c);
+    }
+    return state;
+}
+
+int magi_parse_urlencoded(struct magi_field_list ** list, const char * input)
+{
+    enum st         state = st_name;
+    struct automata a     = { 0, { 0, 0, 0 }, 1, 0 };
+    if (input && *input) {
+        a.list = list;
+        while (state && *input) {
+            switch (state) {
+            case st_name:
+                state = parse_name(&a, *input);
+                break;
+            case st_data:
+                state = parse_data(&a, *input);
+            default:
+                break;
+            }
+            ++input;
+        }
+        if (state == st_data) {
+            state = end_data(&a);
+        } else if (state == st_name) {
+            state = st_error;
+            magi_error_set("[urlencoded] Input ended while reading name.");
+        }
+        free(a.field.name);
+        free(a.field.data);
+    }
+    return state != st_error;
+}
-- 
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