General cleanup: comments and test cases.

Also removed unused function.

encrypt.c

@@ -1,3 +1,21 @@
+/*
+ * The functions in this file are responsible for most of the special
+ * functionality of the purr/meow utilities, which is encrypted pastes
+ * that the server can't access. They can be configured with the RANDOMIZE_IV,
+ * ENCODE_BASE_64 and DECODE_BASE_64 macros from purr.h.
+ *
+ * RANDOMIZE_IV: IV used for AES encryption is randomized or all zero.
+ *
+ * ENCODE_BASE_64: the binary data generated by the encryption process is
+ * encoded as base64.
+ *
+ * DECODE_BASE_64: the data returned by the server is decoded, assuming its
+ * encoding is base64.
+ *
+ * Having all these macros defined is the default mode of operation, and what's
+ * expected by the other PurritoBin clients.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <fcntl.h>
@@ -14,8 +32,7 @@
 #include "mmap_file.h"
 
 /*
- * This function takes an mmap_file struct, and creates an encrypted buffer from it.
- * The created file is passed to an atexit function so it can be deleted automatically.
+ * This function takes an mmap_file struct, and returns an encrypted mmap_file from it.
  * Args:
  *   file: mmap_file for the input file
  *   keyp: will receive the newly generated random key
@@ -64,7 +81,7 @@ struct mmap_file encrypt_mmap(struct mmap_file file, uint8_t **keyp, uint8_t **i
     }
 
     memcpy(rv.data, file.data, file.size);
-    // PKCS#5 padding
+    // PKCS7 padding
     memset(rv.data + file.size, padding, padding);
 
     br_aes_big_cbcenc_keys br = { 0 };
@@ -101,6 +118,13 @@ struct mmap_file encrypt_mmap(struct mmap_file file, uint8_t **keyp, uint8_t **i
     return rv;
 }
 
+/*
+ * This function takes an mmap_file struct, and returns a decrypted buffer from it.
+ * Args:
+ *   file: mmap_file for the input file
+ *   keyp: the key used to encrypt the paste
+ *   ivp: the iv used to encrypt the paste
+ */
 struct mmap_file decrypt_mmap(struct mmap_file file, const uint8_t *key, const uint8_t *iv)
 {
     struct mmap_file rv = {.size = file.size, .prot = PROT_MEM, .flags = MAP_MEM};

formats.c

@@ -5,7 +5,8 @@
 #include "purr.h"
 
 /*
- * Set print to true to print value, otherwise returns dynamic string with the number
+ * Set print to true to print value to stdout,
+ * otherwise returns dynamically allocated string with the number
  */
 char *print_hex(const uint8_t *buf, int len, bool print)
 {
@@ -52,6 +53,11 @@ static uint8_t assemble_u8(const char *cs)
     return rv;
 }
 
+/*
+ * Decode string containing hexadecimal numbers as printed by print_hex().
+ * len should be half the length of the input string, since it's the final length
+ * of the output array.
+ */
 int decode_hex(const char *s, uint8_t *output, int len)
 {
     for (int i = 0; i < len; i++) {

gemini.c

@@ -11,13 +11,7 @@
 
 char *redirect_link = NULL;
 
-static struct gemini_link_node *gimme_node(void)
-{
-    struct gemini_link_node *node = calloc(1, sizeof *node);
-    return node;
-}
-
-static bool is_terminator(char c)
+static bool is_terminator(int c)
 {
     return c == '\n' || c == '\r' || c == 0;
 }

tests.c

@@ -50,6 +50,12 @@ int main()
         const char *expected = "1202124ca8";
         const char *result = print_hex(buf, sizeof buf, false);
         rv = compare_strings(expected, result, "print_hex") ? 1 : rv;
+        const char *hex = "0403124574";
+        uint8_t buf_expected[] = {0x04, 0x03, 0x12, 0x45, 0x74};
+        uint8_t buf_result[sizeof buf_expected];
+        int err = decode_hex(hex, buf_result, sizeof buf_result);
+        rv = compare_arrays(buf_expected, buf_result, sizeof buf_result, "decode_hex") ? 1 : rv;
+        assert(err == 0);
     }
 
     {