/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
   It is considered beerware. Prost. Skol. Cheers or whatever.

   $id$ */

/* System */
#include <string.h>

/* Opentracker */
#include "scan_urlencoded_query.h"
#include "test.h"

/* The scanner returns the number of bytes written to the destination, or
   -1 for a parse error and -2 for a hard terminator encountered before any
   output was produced. It advances the source pointer past the separator it
   stopped on, except for hard terminators and the '&' ending a parameter,
   which it leaves for the next call to see. */

static void case_path(void) {
  char    query[] = "/announce?info_hash=A";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("path stops at the question mark");
  n = scan_urlencoded_query(&p, dest, SCAN_PATH);
  CHECK_INT(n, 9);
  dest[n] = 0;
  CHECK_STR(dest, "/announce");
  CHECK_INT(*p, 'i');
}

static void case_param_and_value(void) {
  char    query[] = "info_hash=abc&port=80";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("parameter stops at '=', value stops at '&'");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
  CHECK_INT(n, 9);
  dest[n] = 0;
  CHECK_STR(dest, "info_hash");

  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 3);
  dest[n] = 0;
  CHECK_STR(dest, "abc");

  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
  CHECK_INT(n, 4);
  dest[n] = 0;
  CHECK_STR(dest, "port");

  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 2);
  dest[n] = 0;
  CHECK_STR(dest, "80");
}

static void case_percent_decoding(void) {
  char    query[] = "%41%42%43&x=1";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("percent escapes decode");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 3);
  CHECK_MEM(dest, "ABC", 3);
}

static void case_binary_info_hash(void) {
  /* The twenty byte info_hash is what the announce path really decodes */
  char          query[] = "%00%01%02%ff%fe%7f%80ABCDEFGHIJKLM&x=1";
  unsigned char want[]  = {0x00, 0x01, 0x02, 0xff, 0xfe, 0x7f, 0x80, 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M'};
  char          dest[64];
  char         *p = query;
  ssize_t       n;

  test_case("twenty byte binary value survives decoding");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 20);
  CHECK_MEM(dest, want, 20);
}

static void case_in_place(void) {
  char    query[] = "%41%42&x=1";
  char   *p       = query;
  ssize_t n;

  test_case("decoding in place over the source is safe");
  n = scan_urlencoded_query(&p, query, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 2);
  CHECK_MEM(query, "AB", 2);
}

static void case_bad_escape(void) {
  char    query[] = "%zz";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("a non hexadecimal escape is a parse error");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, -1);
}

static void case_truncated_escape(void) {
  char    query[] = "%4";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("an escape cut short by the terminator is a parse error");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, -1);
}

static void case_terminator(void) {
  char    empty[] = "";
  char    space[] = " rest";
  char    dest[64];
  char   *p = empty;
  ssize_t n;

  test_case("a hard terminator before any output reports end of input");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
  CHECK_INT(n, -2);

  p = space;
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_PARAM);
  CHECK_INT(n, -2);
}

static void case_terminator_after_output(void) {
  char    query[] = "abc";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("a hard terminator after output is left for the next call");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 3);
  CHECK_INT(*p, 0);
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, -2);
}

/* The character matrix makes '?' terminate a path only, and '=' terminate a
   path or a parameter only. Both are ordinary characters inside a value, so a
   value is free to contain a nested query string. */

static void case_separators_are_contextual(void) {
  char    question[] = "a?b&x=1";
  char    equals[]   = "a=b&x=1";
  char    dest[64];
  char   *p = question;
  ssize_t n;

  test_case("a question mark is literal inside a value");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 3);
  dest[n] = 0;
  CHECK_STR(dest, "a?b");

  test_case("an equals sign is literal inside a value");
  p = equals;
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, 3);
  dest[n] = 0;
  CHECK_STR(dest, "a=b");
}

static void case_ampersand_in_path(void) {
  char    query[] = "/path&x";
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("an ampersand in a path is a parse error");
  n = scan_urlencoded_query(&p, dest, SCAN_PATH);
  CHECK_INT(n, -1);
}

static void case_raw_high_byte(void) {
  char    query[] = {'a', 'b', (char)0x80, 0};
  char    dest[64];
  char   *p = query;
  ssize_t n;

  test_case("an undecoded byte above ASCII is a parse error");
  n = scan_urlencoded_query(&p, dest, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(n, -1);
}

static void case_skipvalue(void) {
  char  query[] = "abc&next=1";
  char  bare[]  = "abc";
  char *p       = query;

  test_case("skipvalue steps over the value and its separator");
  scan_urlencoded_skipvalue(&p);
  CHECK_STR(p, "next=1");

  test_case("skipvalue leaves a hard terminator in place");
  p = bare;
  scan_urlencoded_skipvalue(&p);
  CHECK_INT(*p, 0);
}

static void case_find_keywords(void) {
  static const ot_keywords keywords[] = {{"port", 1}, {"left", 2}, {"compact", 3}, {NULL, -3}};
  char                     match[]    = "left=0";
  char                     nomatch[]  = "bogus=1";
  char                     prefix[]   = "por=1";
  char                    *p          = match;

  test_case("a known keyword returns its value");
  CHECK_INT(scan_find_keywords(keywords, &p, SCAN_SEARCHPATH_PARAM), 2);

  test_case("an unknown keyword returns -3");
  p = nomatch;
  CHECK_INT(scan_find_keywords(keywords, &p, SCAN_SEARCHPATH_PARAM), -3);

  test_case("a prefix of a keyword does not match it");
  p = prefix;
  CHECK_INT(scan_find_keywords(keywords, &p, SCAN_SEARCHPATH_PARAM), -3);
}

static void case_fixed_int(void) {
  char positive[] = "123";
  char negative[] = "-45";
  char trailing[] = "12a";
  int  value;

  test_case("scan_fixed_int returns the count of unparsed bytes");
  CHECK_INT(scan_fixed_int(positive, 3, &value), 0);
  CHECK_INT(value, 123);

  CHECK_INT(scan_fixed_int(negative, 3, &value), 0);
  CHECK_INT(value, -45);

  CHECK_INT(scan_fixed_int(trailing, 3, &value), 1);
  CHECK_INT(value, 12);
}

static void case_fixed_int_bounded(void) {
  char digits[] = "12345";
  int  value;

  test_case("scan_fixed_int honours the length it is given");
  CHECK_INT(scan_fixed_int(digits, 3, &value), 0);
  CHECK_INT(value, 123);
}


/* The encoding direction. Which bytes survive unescaped is fixed by what
   existing parsers of the urlencoded full scrape expect, so these cases pin
   the set rather than describe a preference. */

static void case_fmt_passes_safe_bytes(void) {
  const uint8_t src[] = "aZ09$-./=_~";
  char          dest[64];
  size_t        n;

  test_case("alphanumerics and the safe punctuation pass through");
  n       = fmt_urlencoded(dest, src, 11);
  dest[n] = 0;
  CHECK_INT(n, 11);
  CHECK_STR(dest, "aZ09$-./=_~");
}

static void case_fmt_escapes_the_rest(void) {
  const uint8_t src[] = {' ', '%', '&', '+', ':', '?'};
  char          dest[64];
  size_t        n;

  test_case("everything else becomes a percent escape");
  n       = fmt_urlencoded(dest, src, sizeof(src));
  dest[n] = 0;
  CHECK_INT(n, 18);
  CHECK_STR(dest, "%20%25%26%2b%3a%3f");
}

static void case_fmt_hex_is_lower_case(void) {
  const uint8_t src[] = {0x00, 0xab, 0xff};
  char          dest[64];
  size_t        n;

  test_case("escapes use lower case hex digits");
  n       = fmt_urlencoded(dest, src, sizeof(src));
  dest[n] = 0;
  CHECK_INT(n, 9);
  CHECK_STR(dest, "%00%ab%ff");
}

static void case_fmt_length_only(void) {
  const uint8_t src[] = {'a', 0xff, 'b'};

  test_case("a null destination reports the length without writing");
  CHECK_INT(fmt_urlencoded(NULL, src, sizeof(src)), 5);
  CHECK_INT(fmt_urlencoded(NULL, src, 0), 0);
}

static void case_fmt_zero_length(void) {
  char dest[4];

  test_case("a zero length input writes nothing");
  memset(dest, 0x5a, sizeof(dest));
  CHECK_INT(fmt_urlencoded(dest, (const uint8_t *)"abc", 0), 0);
  CHECK_MEM(dest, "\x5a\x5a\x5a\x5a", 4);
}

static void case_fmt_worst_case_fits(void) {
  uint8_t src[20];
  char    dest[61];
  size_t  i, n;

  test_case("a hash of entirely unsafe bytes needs three times its length");
  for (i = 0; i < sizeof(src); ++i)
    src[i] = 0xff;
  n       = fmt_urlencoded(dest, src, sizeof(src));
  dest[n] = 0;
  CHECK_INT(n, 60);
  for (i = 0; i < 20; ++i)
    if (memcmp(dest + 3 * i, "%ff", 3)) {
      test_failf(__FILE__, __LINE__, "escape %zu is wrong", i);
      return;
    }
  ++test_checks;
}

static void case_fmt_decoder_disagrees_on_dollar(void) {
  /* Documenting a known asymmetry rather than a wish. Of the bytes the
     encoder passes through unescaped, '$' is the only one the decoder then
     refuses, and it refuses the whole string rather than stopping short.
     Output of the urlencoded full scrape therefore does not round trip
     through scan_urlencoded_query when a hash contains 0x24. Harmless today
     because only third party tooling reads that output. */
  const uint8_t src[]  = {'a', '$', 'b'};
  char          dest[16];
  char          scanned[16];
  char         *p = dest;
  size_t        n;
  ssize_t       got;

  test_case("the encoder passes '$' but the decoder rejects it");
  n       = fmt_urlencoded(dest, src, sizeof(src));
  dest[n] = 0;
  CHECK_STR(dest, "a$b");

  got = scan_urlencoded_query(&p, scanned, SCAN_SEARCHPATH_VALUE);
  CHECK_INT(got, -1);
}

void test_scan_urlencoded_query(void) {
  case_path();
  case_param_and_value();
  case_percent_decoding();
  case_binary_info_hash();
  case_in_place();
  case_bad_escape();
  case_truncated_escape();
  case_terminator();
  case_terminator_after_output();
  case_separators_are_contextual();
  case_ampersand_in_path();
  case_raw_high_byte();
  case_skipvalue();
  case_find_keywords();
  case_fixed_int();
  case_fixed_int_bounded();
  case_fmt_passes_safe_bytes();
  case_fmt_escapes_the_rest();
  case_fmt_hex_is_lower_case();
  case_fmt_length_only();
  case_fmt_zero_length();
  case_fmt_worst_case_fits();
  case_fmt_decoder_disagrees_on_dollar();
}