testing: test many possible truncated SOCKS commands

Many of the 'truncated command' paths in fetch_from_buf_socks() were
not reached by the tests.  This new unit test tries to check them
exhaustively.

src/test/test_socks.c

@@ -497,6 +497,105 @@ test_socks_5_malformed_commands(void *ptr)
   ;
 }
 
+/** check for correct behavior when the socks command has not arrived. */
+static void
+test_socks_truncated(void *ptr)
+{
+  const struct {
+    enum { NONE, AUTH, ALL } setup;
+    const char *body;
+    size_t len;
+  } commands[] = {
+    /* SOCKS4 */
+    /* Connect, to an IP. */
+    { NONE, "\x04\x01\x05\x05\x01\x02\x03\x04\x00", 9},
+    /* Connect, to an IP, with authentication. */
+    { NONE, "\x04\x01\x05\x05\x01\x02\x03\x04hello\x00", 14},
+    /* SOCKS4A */
+    /* Connect, to a hostname */
+    { NONE, "\x04\x01\x09\x09\x00\x00\x00\x01\x00www.example.com\x00", 25},
+    /* Connect, to a hostname, with authentication */
+    { NONE, "\x04\x01\x09\x09\x00\x00\x00\x01hi\x00www.example.com\x00", 27},
+    /* SOCKS5 */
+    /* initial handshake */
+    { NONE, "\x05\x00", 2 },
+    /* no-auth handshake */
+    { NONE, "\x05\x03\x99\x21\x10", 5 },
+    /* SOCSK5, username-password, all empty. */
+    { AUTH, "\x01\x00\x00", 3 },
+    /* SOCSK5, username-password, 1 char each. */
+    { AUTH, "\x01\x01x\x01y", 5 },
+    /* SOCSK5, username-password, max length. */
+    { AUTH, "\x01\xff"
+      "Ogni tempo ha il suo fascismo: se ne notano i segni premonitori "
+      "dovunque la concentrazione di potere nega al cittadino la "
+      "possibilit\xc3\xa0 e la capacit\xc3\xa0 di esprimere ed attuare la "
+      "sua volont\xc3\xa0. A questo si arriva in molti modi, non "
+      "necessariamente col terror"
+      "\xff"
+      "e dell'intimidazione poliziesca, ma anche negando o distorcendo "
+      "l'informazione, inquinando la giustizia, paralizzando la scuola, "
+      "diffondendo in molti modi sottili la nostalgia per un mondo in cui "
+      "regnava sovrano l'ordine, ed in cui la sicurezza dei pochi "
+      /* privilegiati riposava sul lavoro forzato e sul silenzio forzato dei
+         molti. -- Primo Levi */ , 513 },
+    /* Socks5, IPv4 address */
+    { ALL, "\x05\x01\x00\x01\x01\x02\x03\x04\x20\x20", 10 },
+    /* Socks5, IPv6 address */
+    { ALL, "\x05\x01\x00\x04"
+      "\x49\x20\x48\x41\x5a\x20\x45\x41\x53\x54\x45\x52\x20\x45\x47\x47"
+      "\x20\x20", 22 },
+    /* Socks5, hostname, empty. */
+    { ALL, "\x05\x01\x00\x03" "\x00" "\x00\x50", 7 },
+    /* Socks5, hostname, moderate. */
+    { ALL, "\x05\x01\x00\x03" "\x11" "onion.example.com" "\x00\x50", 24 },
+    /* Socks5, hostname, maximum. */
+    { ALL, "\x05\x01\x00\x03" "\xff"
+      "whatsoever.I.shall.see.or.hear.in.the.course.of.my.profession.as.well."
+      "as.outside.my.profession.in.my.intercourse.with.men.if.it.be.what."
+      "should.not.be.published.abroad.I.will.never.divulge.holding.such."
+      "things.to.be.holy.secrets.x.hippocratic.oath.wikipedia"
+      "\x00\x50", 262 },
+  };
+  unsigned i, j;
+  SOCKS_TEST_INIT();
+  for (i = 0; i < ARRAY_LENGTH(commands); ++i) {
+    for (j = 0; j < commands[i].len; ++j) {
+      switch (commands[i].setup) {
+        default: /* Falls through */
+        case NONE:
+          /* This test calls for no setup on the socks state. */
+          break;
+        case AUTH:
+          /* This test calls for the socks state to be waiting for
+           * username/password authentication */
+          ADD_DATA(buf, "\x05\x01\x02");
+          tt_int_op(0, OP_EQ, fetch_from_buf_socks(buf, socks, 0, 0));
+          tt_int_op(0, OP_EQ, buf_datalen(buf));
+          break;
+        case ALL:
+          /* This test calls for the socks state to be waiting for
+           * the connection request */
+          ADD_DATA(buf, "\x05\x01\x00");
+          tt_int_op(0, OP_EQ, fetch_from_buf_socks(buf, socks, 0, 0));
+          tt_int_op(0, OP_EQ, buf_datalen(buf));
+      }
+
+      TT_BLATHER(("Checking command %u, length %u, omitting char %u", i, j,
+                  (unsigned)commands[i].body[j]));
+      buf_add(buf, commands[i].body, j);
+      /* This should return 0 meaning "not done yet" */
+      tt_int_op(0, OP_EQ, fetch_from_buf_socks(buf, socks, 0, 0));
+      tt_uint_op(j, OP_EQ, buf_datalen(buf)); /* Nothing was drained */
+      buf_clear(buf);
+      socks_request_free(testdata->req);
+      socks = testdata->req = socks_request_new();
+    }
+  }
+  done:
+  ;
+}
+
 #define SOCKSENT(name)                                  \
   { #name, test_socks_##name, TT_FORK, &socks_setup, NULL }
 
@@ -512,6 +611,8 @@ struct testcase_t socks_tests[] = {
   SOCKSENT(5_authenticate_with_data),
   SOCKSENT(5_malformed_commands),
 
+  SOCKSENT(truncated),
+
   END_OF_TESTCASES
 };