keyrelay/tests/test_conn.cpp

/**
 * tests/test_conn.cpp -- the pure half of src/conn.h, walked on the host. No Arduino, no
 * WiFiClient, no socket: exactly like tls_pem.h and the policy half of tls_session.h, the
 * header keeps its deciding logic free of library includes so the identical code runs here
 * under -fsanitize=address,undefined. `kr::Conn` itself hides behind ESP_PLATFORM and is
 * proven the other way (both firmware environments link, plus the device rows in
 * .agents/HW_VERIFICATION.md: page byte-exact over TLS, :80 redirecting, plaintext /ws
 * refused with 426).
 *
 * What each check pins, and the failure it is defending:
 *
 *   renderHttpResponseHead -- one header formatter for every route, port and transport.
 *                      snprintf truncation used to become `headLen = 0`, which became "the
 *                      board answered nothing". Here: the exact bytes, the Content-Length
 *                      agreeing with the body, an extra header landing in the right place,
 *                      and the widest legal response PROVABLY fitting kHttpResponseHeadCap.
 *   queryCarriesToken -- the :80 rule "a URL carrying the passphrase is never redirected".
 *                      The boundary matters: a check that matched the substring would turn
 *                      /status?mytoken=x into a 426, and one that missed `&token=` would
 *                      redirect the real thing and leak the passphrase a second time.
 *   plaintextRoute     -- the whole :80 answer table, including that the -D KR_TLS=0
 *                      rollback answers everything (the rollback must stay buildable and
 *                      must stay today's server).
 *   redirectAuthority  -- an attacker-controlled `Host:` becoming a `Location:` a browser
 *                      navigates to. `http://keyrelay.local@evil.com/` is the shape that
 *                      makes this a real open redirect, not a theoretical one.
 *   renderRedirectTarget -- the request path is client text too, and a CR in it would
 *                      inject headers into the board's own response.
 *   FlashSend          -- the page's send cursor. An off-by-one here is a page that arrives
 *                      a byte short and parses as garbage; a next() that ignores the budget
 *                      is one loop() iteration spending an unbounded time writing a socket.
 *
 * Two defects in this new code were found by the SANITISED run of this file, not by its
 * assertions, and both are pinned by the case that triggered them:
 *   - queryCarriesToken() memcmp()ed its 6-byte key against the tail of any shorter query,
 *     reading past the end of `"a=1"` (global-buffer-overflow);
 *   - dottedQuadPrivate() checked the octet count when a dot arrived instead of before each
 *     digit, so `"192.168.1.1.1"` wrote octets[4] (stack-buffer-overflow).
 * Neither changes an answer on a healthy input, and neither is visible on the board until
 * it isn't. That is the argument for `SANITIZE=1` being part of the gate rather than an
 * option (AGENTS.md: the sanitiser run found five of the ten bugs the README documents).
 */
#include <string.h>

#include "test.h"

#include "conn.h"

using kr::FlashSend;
using kr::kConnTxCap;
using kr::kConnViewTxCap;
using kr::kConnWriteChunk;
using kr::kHttpResponseHeadCap;
using kr::kPageBytesPerTick;
using kr::kPageChunkBytes;
using kr::kStatusJsonCap;
using kr::plaintextRoute;
using kr::PlainRoute;
using kr::queryCarriesToken;
using kr::redirectAuthority;
using kr::renderHttpResponseHead;
using kr::renderRedirectTarget;

namespace {

// The served page's length, in bytes. Cross-checked against the real raw strings by
// tests/test_relayctl.py ("the page the transport sends"). The page carries one
// 19-byte #if KR_TLS build marker and both spellings are the same length, so this
// number is build-independent -- a fact test_relayctl pins, not a hope.
constexpr size_t kServedPageBytes = 51626;

/** The pump's shape, without a socket: hand out chunks, accept what a peer takes. */
struct DrainLog {
  size_t pieces = 0;
  size_t bytes = 0;
  size_t maxPiece = 0;
};

}  // namespace

int main() {
  char head[kHttpResponseHeadCap];

  // ------------------------------------------------------ the response head
  CASE("head: the exact bytes of a plain 200");
  const size_t n = renderHttpResponseHead(head, sizeof(head), "200 OK",
                                          "text/plain; charset=utf-8", 5);
  CHECK_STR(head,
            "HTTP/1.1 200 OK\r\n"
            "Content-Type: text/plain; charset=utf-8\r\n"
            "Content-Length: 5\r\n"
            "Cache-Control: no-store\r\n"
            "X-Content-Type-Options: nosniff\r\n"
            "Connection: close\r\n\r\n");
  CHECK_EQ(n, strlen(head));
  CHECK(n > 0 && n < kHttpResponseHeadCap);

  CASE("head: the extra header sits before Connection");
  CHECK(renderHttpResponseHead(head, sizeof(head), "301 Moved Permanently",
                               "text/html; charset=utf-8", 0,
                               "Location: https://keyrelay.local/\r\n") > 0);
  CHECK(strstr(head, "Location: https://keyrelay.local/\r\nConnection: close") != nullptr);

  CASE("head: 426 carries the Upgrade field RFC 4266 asks for");
  CHECK(renderHttpResponseHead(head, sizeof(head), "426 Upgrade Required",
                               "text/plain; charset=utf-8", 40,
                               "Upgrade: TLS/1.2, HTTP/1.1\r\n") > 0);
  CHECK(strstr(head, "Upgrade: TLS/1.2, HTTP/1.1\r\n") != nullptr);
  CHECK(strstr(head, "Content-Length: 40\r\n") != nullptr);

  CASE("head: too small a buffer is refused, never truncated");
  char tiny[16] = "AAAAAAAAAAAAAAA";
  CHECK_EQ(renderHttpResponseHead(tiny, sizeof(tiny), "200 OK", "text/plain", 1), 0);
  CHECK_EQ(tiny[0], 'A');                      // nothing written at all
  CHECK_EQ(renderHttpResponseHead(nullptr, 64, "200 OK", "text/plain", 1), 0);
  // The formatter's contract is the SHIPPED cap, so a caller passing anything else gets a
  // refusal rather than a head built to a size nobody sized.
  char almost[kHttpResponseHeadCap];
  CHECK_EQ(renderHttpResponseHead(almost, kHttpResponseHeadCap - 1, "200 OK", "text/plain",
                                  1), 0);

  CASE("head: the widest legal response fits, with margin to spare");
  // The widest authority redirectAuthority() will actually accept is a dotted quad
  // (kCertCommonName is longer than any IP, and nothing else passes the name test); the
  // widest path it carries over is /index.html. So this is not a hypothetical worst case,
  // it is reachable -- and it must fit anyway, with room left for the next header.
  char authority[80];
  CHECK(redirectAuthority("192.168.123.234", authority, sizeof(authority)));
  char loc[128];
  const size_t locLen = renderRedirectTarget("192.168.123.234", "/index.html", loc,
                                             sizeof(loc));
  CHECK(locLen > 0);
  char extra[160];
  const int extraLen = snprintf(extra, sizeof(extra), "Location: %s\r\n", loc);
  CHECK(extraLen > 0);
  const size_t wide = renderHttpResponseHead(head, sizeof(head), "301 Moved Permanently",
                                             "text/plain; charset=utf-8", 128, extra);
  CHECK(wide > 0);
  CHECK(wide < kHttpResponseHeadCap);
  CHECK(kHttpResponseHeadCap - wide >= 32);    // room for one more header, not slack

  // -------------------------------------------------- the token-in-URL test
  CASE("query: token= is found where a key can start");
  CHECK(queryCarriesToken("token=secret"));
  CHECK(queryCarriesToken("a=1&token=secret"));
  CHECK(queryCarriesToken("a=1&b=2&token=x"));
  CHECK(queryCarriesToken("token="));          // an empty token is still a token carried

  CASE("query: look-alikes are not token-carrying");
  CHECK(!queryCarriesToken(""));
  CHECK(!queryCarriesToken(nullptr));
  CHECK(!queryCarriesToken("mytoken=secret"));   // not a key boundary
  CHECK(!queryCarriesToken("a=mytoken"));
  CHECK(!queryCarriesToken("status?token"));     // no '='
  CHECK(!queryCarriesToken("xtoken=secret"));
  CHECK(!queryCarriesToken("a=1token=secret"));  // '=' is not a key boundary

  CASE("query: every short prefix is scanned without reading past the string");
  // ASan caught the first version doing exactly this: comparing a 6-byte key against the
  // tail of "a=1" reads four bytes that are not there. Nothing about the answer changes;
  // what changes is whether the board walks off the end of a buffer on a router's URL.
  static const char *const kShort[] = {"t", "to", "tok", "toke", "token", "=", "&", "a=1",
                                       "a=1&", "a=1&b", "x&token=", "&&token=x"};
  for (const char *const shortq : kShort) {
    const bool want = std::strcmp(shortq, "x&token=") == 0 ||
                      std::strcmp(shortq, "&&token=x") == 0;
    CHECK_EQ(queryCarriesToken(shortq) ? 1 : 0, want ? 1 : 0);
  }

  CASE("route: the :80 table, in one place, for both builds");
  // tlsBuild == false is the -D KR_TLS=0 rollback: every shape is served, exactly as
  // before phase 02. That is the rollback criterion, and it is a row of this table.
  CHECK(plaintextRoute(false, "token=x", false) == PlainRoute::Serve);
  CHECK(plaintextRoute(true, nullptr, false) == PlainRoute::Serve);
  CHECK(plaintextRoute(false, nullptr, false) == PlainRoute::Serve);
  // tlsBuild == true: nothing on :80 is served; an upgrade and a token both get 426; the
  // rest get the redirect. 426 before redirect, for the token, always.
  CHECK(plaintextRoute(false, nullptr, true) == PlainRoute::Redirect);
  CHECK(plaintextRoute(false, "a=1", true) == PlainRoute::Redirect);
  CHECK(plaintextRoute(false, "token=secret", true) == PlainRoute::UpgradeRequired);
  CHECK(plaintextRoute(true, nullptr, true) == PlainRoute::UpgradeRequired);
  // A /ws upgrade carrying a token is still an upgrade: the transport answer wins, and it
  // is the more fundamental one ("this port does not speak that at all").
  CHECK(plaintextRoute(true, "token=secret", true) == PlainRoute::UpgradeRequired);

  // -------------------------------------------------- the redirect authority
  CASE("authority: the names this board is reached at survive");
  char auth[80];
  CHECK(redirectAuthority("keyrelay.local", auth, sizeof(auth)));
  CHECK_STR(auth, "keyrelay.local");
  CHECK(redirectAuthority("KEYRELAY.LOCAL", auth, sizeof(auth)));
  CHECK_STR(auth, "keyrelay.local");
  CHECK(redirectAuthority("keyrelay", auth, sizeof(auth)));
  CHECK_STR(auth, "keyrelay");
  // "IP if the name fails" is in the README; a redirect that threw the IP away would
  // break the documented fallback path.
  CHECK(redirectAuthority("192.168.4.1", auth, sizeof(auth)));
  CHECK_STR(auth, "192.168.4.1");
  CHECK(redirectAuthority("10.2.0.22:80", auth, sizeof(auth)));
  CHECK_STR(auth, "10.2.0.22");                 // :port stripped, the scheme's own is implied
  CHECK(redirectAuthority("172.20.1.9", auth, sizeof(auth)));
  CHECK_STR(auth, "172.20.1.9");

  CASE("authority: everything else falls back to the certificate's name");
  // Each of these would otherwise put attacker-chosen text into a Location a browser
  // follows. The @ one is the shape of a real open-redirect URL.
  static const char *const kRejected[] = {
      "evil.com", "keyrelay.local@evil.com", "keyrelay.local.evil.com", "evil.local",
      "1.2.3.4", "8.8.8.8:443", "keyrela", "keyrelay.too", "-bad", "bad-", ".local", "",
      "a b", "a\re", "::1", "192.168.1", "192.168.1.1.1", "300.1.1.1", "172.32.0.1",
      "host:80:90",
  };
  for (const char *const bad : kRejected) {
    CHECK(redirectAuthority(bad, auth, sizeof(auth)));
    CHECK_STR(auth, kr::kCertCommonName);
  }
  CHECK(redirectAuthority(nullptr, auth, sizeof(auth)));
  CHECK_STR(auth, kr::kCertCommonName);
  char longish[300];
  memset(longish, 'a', sizeof(longish) - 1);
  longish[sizeof(longish) - 1] = '\0';
  CHECK(redirectAuthority(longish, auth, sizeof(auth)));
  CHECK_STR(auth, kr::kCertCommonName);         // truncated, then refused: never echoed
  CHECK(!redirectAuthority("keyrelay.local", auth, 4));   // cannot even hold the fallback

  CASE("redirect target: only the two content paths travel");
  CHECK(renderRedirectTarget("keyrelay.local", "/", loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/");
  CHECK(renderRedirectTarget("keyrelay.local", "/index.html", loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/index.html");
  CHECK(renderRedirectTarget("keyrelay.local", "/nope", loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/");    // 404 awaits on the encrypted port
  // Header injection: the request target is client bytes, and Location is a header.
  CHECK(renderRedirectTarget("keyrelay.local", "/a\r\nX-Evil: 1", loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/");
  CHECK(renderRedirectTarget("keyrelay.local", "/a\nX-Evil: 1", loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/");
  CHECK(renderRedirectTarget("keyrelay.local", "", loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/");
  CHECK(renderRedirectTarget("keyrelay.local", nullptr, loc, sizeof(loc)) > 0);
  CHECK_STR(loc, "https://keyrelay.local/");
  CHECK_EQ(renderRedirectTarget("keyrelay.local", "/", loc, 4), 0);   // would not fit
  CHECK_EQ(renderRedirectTarget("keyrelay.local", "/", nullptr, 16), 0);
  // and no redirect body ever contains a query
  CHECK(renderRedirectTarget("192.168.4.1", "/index.html", loc, sizeof(loc)) > 0);
  CHECK(strchr(loc, '?') == nullptr);

  // ------------------------------------------------------ the flash send
  CASE("flash send: empty and null are inert");
  FlashSend fs;
  CHECK(!fs.armed());
  CHECK(fs.done());
  CHECK_EQ(fs.sent(), 0);
  CHECK_EQ(fs.total(), 0);
  CHECK_EQ(fs.next(100, 100), 0);
  fs.start(nullptr, 10);
  CHECK(!fs.armed());
  CHECK_EQ(fs.total(), 0);
  fs.start("abc", 0);                            // a zero-length body is nothing to send
  CHECK(!fs.armed());
  CHECK(fs.done());

  CASE("flash send: one chunk at a time, in order, clamped");
  static const char page[] = "0123456789ABCDEFGHIJ";   // 20 bytes
  fs.start(page, sizeof(page) - 1);
  CHECK(fs.armed());
  CHECK(!fs.done());
  CHECK_EQ(fs.total(), 20);
  CHECK_EQ(fs.remaining(), 20);
  CHECK_EQ(fs.next(8, 100), 8);                  // chunk cap
  CHECK_EQ(fs.next(8, 5), 5);                    // budget cap, whichever is smaller
  CHECK_EQ(fs.next(8, 0), 0);                    // no budget: nothing to hand out
  CHECK_EQ(fs.next(0, 100), 0);
  char out[32];
  memset(out, '.', sizeof(out));
  fs.copyTo(out, 8);
  CHECK(memcmp(out, "01234567", 8) == 0);
  fs.copyTo(out, 999);                           // clamped to what is left, no overrun
  CHECK_EQ(out[20], '.');
  fs.advance(8);
  CHECK_EQ(fs.sent(), 8);
  CHECK_EQ(fs.remaining(), 12);
  fs.advance(0);                                 // the retry path: identical bytes again
  CHECK_EQ(fs.sent(), 8);
  fs.copyTo(out, 4);
  CHECK(memcmp(out, "89AB", 4) == 0);

  CASE("flash send: completing keeps the totals readable");
  DrainLog log;
  fs.start(page, sizeof(page) - 1);
  while (fs.armed()) {
    const size_t take = fs.next(8, 100);
    if (take == 0) break;
    fs.copyTo(out, take);
    // every byte of the piece is the page's, at the cursor: the whole claim of the pump
    for (size_t i = 0; i < take; i++)
      CHECK(out[i] == page[log.bytes + i]);
    log.bytes += take;
    log.pieces++;
    if (take > log.maxPiece) log.maxPiece = take;
    fs.advance(take);
  }
  CHECK(fs.done());
  CHECK(!fs.armed());
  CHECK_EQ(log.bytes, 20);
  CHECK_EQ(log.pieces, 3);                       // 8 + 8 + 4
  CHECK_EQ(log.maxPiece, 8);
  CHECK_EQ(fs.sent(), 20);                       // sent()/total() still describe the send
  CHECK_EQ(fs.remaining(), 0);
  fs.advance(5);                                 // past the end: clamped, no wrap
  CHECK_EQ(fs.sent(), 20);

  CASE("flash send: the real page, on the real budget");
  // 51 626 bytes (the count .agents/validate.sh prints) through kPageChunkBytes per write
  // and kPageBytesPerTick per tick: the exact numbers the device check compares against.
  {
    // A stand-in of the served page's size (51 626 B, the `page bytes:` line the gate
    // prints). tests/test_relayctl.py pins this constant against the raw string in
    // src/web_page.h, so if the page changes and this number does not, a check fails --
    // the same "test the table" rule as the mouse bits and the evdev codes.
    static const char big[kServedPageBytes] = {0};
    FlashSend p;
    p.start(big, sizeof(big));
    size_t ticks = 0, total = 0, worstTick = 0, worstPiece = 0;
    while (p.armed() && ticks < 1000) {
      size_t thisTick = 0;
      while (p.armed()) {
        const size_t take = p.next(kPageChunkBytes, kPageBytesPerTick - thisTick);
        if (take == 0) break;
        CHECK(take <= kPageChunkBytes);
        thisTick += take;
        CHECK(thisTick <= kPageBytesPerTick);
        total += take;
        if (take > worstPiece) worstPiece = take;
        p.advance(take);
      }
      CHECK(thisTick <= kPageBytesPerTick);
      if (thisTick > worstTick) worstTick = thisTick;
      ticks++;
    }
    CHECK(p.done());
    CHECK_EQ(total, sizeof(big));
    CHECK(worstPiece <= kPageChunkBytes);
    CHECK(worstTick <= kPageBytesPerTick);
    // 51 626 / 1460 = 36 chunks; / 5840 per tick = 9 ticks. If either number changes in
    // config.h this line moves, and the report has to move with it.
    CHECK_EQ((sizeof(big) + kPageBytesPerTick - 1) / kPageBytesPerTick, 9);
    CHECK_EQ((sizeof(big) + kPageChunkBytes - 1) / kPageChunkBytes, 36);
  }

  CASE("config: the sizing this layer promises");
  {
    // One transport write is never bigger than the transport's own record cap, and the
    // per-tick budget is a whole number of chunks -- otherwise the last write of a tick
    // would be a runt and the arithmetic above would have a special case in it.
    CHECK(kPageChunkBytes <= kConnWriteChunk);
    CHECK_EQ(kPageBytesPerTick % kPageChunkBytes, 0);
    CHECK(kPageBytesPerTick >= kPageChunkBytes);
    // The spare slot must be able to hold the widest response it can be asked to send:
    // a head and its body are queued as a PAIR, so the pair has to fit.
    CHECK_EQ(kConnViewTxCap, kHttpResponseHeadCap + kStatusJsonCap);
    CHECK(kConnTxCap >= kHttpResponseHeadCap + kStatusJsonCap);
    CHECK(kConnTxCap >= kStatusJsonCap + 16);   // a whole status frame, as before
  }

  return report("test_conn");
}