Fix three network-facing overflows in the FTP and Java parsers

get_ftp_line() copied a server reply byte-by-byte into a fixed char[1024]
with no index bound, so a hostile or MITM FTP server could smash the stack
with an over-long CRLF-less line. Bound the write and truncate.

The ftp:// userinfo parser copied "user:pass@" into user[256]/pass[256] with
two unbounded loops, overflowing from a long userinfo supplied by a hostile
ftp:// link. Extract the split into ftp_split_userpass(), which truncates
each field to fit.

The Java .class parser did calloc(header.count, sizeof(RESP_STRUCT)) on an
attacker-controlled u2 count, allocating ~68 MB per crafted class (DoS). Cap
the count to the file size (each constant-pool entry is at least one byte on
disk) via a new hts_count_fits() guard, and move the alloc/free to the
bounds-checked calloct/freet wrappers.

Self-tests: ftp-line drives get_ftp_line over a socketpair with a 4 KB reply,
ftp-userpass feeds an over-long userinfo, java exercises the count cap. The
first two abort under ASan on the pre-fix code.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

src/htsftp.c

@@ -128,6 +128,31 @@ void launch_ftp(FTPDownloadStruct * params) {
   return 0; \
   }
 
+/* Bounded split of a hostile-URL "user[:pass]@" prefix (see htsftp.h). */
+void ftp_split_userpass(const char *src, const char *end, char *user,
+                        size_t user_size, char *pass, size_t pass_size) {
+  size_t n = 0;
+
+  while (src[n] != '\0' && src[n] != ':') {
+    if (n < user_size - 1)
+      user[n] = src[n];
+    n++;
+  }
+  user[n < user_size ? n : user_size - 1] = '\0';
+  pass[0] = '\0';
+  if (src[n] == ':') { // password follows the colon
+    const size_t base = n + 1;
+    size_t k = 0;
+
+    while (&src[base + k + 1] < end && src[base + k] != '\0') {
+      if (k < pass_size - 1)
+        pass[k] = src[base + k];
+      k++;
+    }
+    pass[k < pass_size ? k : pass_size - 1] = '\0';
+  }
+}
+
 // la véritable fonction une fois lancées les routines thread/fork
 int run_launch_ftp(FTPDownloadStruct * pStruct) {
   lien_back *back = pStruct->pBack;
@@ -173,24 +198,7 @@ int run_launch_ftp(FTPDownloadStruct * pStruct) {
   while(*real_adr == '/')
     real_adr++;                 // sauter /
   if ((adr = jump_identification(real_adr)) != real_adr) {      // user
-    int i = -1;
+    ftp_split_userpass(real_adr, adr, user, sizeof(user), pass, sizeof(pass));
-
-    pass[0] = '\0';
-    do {
-      i++;
-      user[i] = real_adr[i];
-    } while((real_adr[i] != ':') && (real_adr[i]));
-    user[i] = '\0';
-    if (real_adr[i] == ':') {   // pass
-      int j = -1;
-
-      i++;                      // oui on saute aussi le :
-      do {
-        j++;
-        pass[j] = real_adr[i + j];
-      } while(((&real_adr[i + j + 1]) < adr) && (real_adr[i + j]));
-      pass[j] = '\0';
-    }
   }
   // Calculer RETR <nom>
   {
@@ -984,8 +992,8 @@ int get_ftp_line(T_SOC soc, char *ptrline, size_t line_size, int timeout) {
       //case 0: break;    // pas encore --> erreur (on attend)!
     case 1:
       HTS_STAT.HTS_TOTAL_RECV += 1;     // compter flux entrant
-      if ((b != 10) && (b != 13))
+      if ((b != 10) && (b != 13) && (i < (int) sizeof(data) - 1))
-        data[i++] = b;
+        data[i++] = b; // truncate hostile over-long reply lines
       break;
     default:
       if (ptrline)

src/htsftp.h

@@ -70,6 +70,10 @@ int back_launch_ftp(FTPDownloadStruct * params);
 int run_launch_ftp(FTPDownloadStruct * params);
 int send_line(T_SOC soc, const char *data);
 int get_ftp_line(T_SOC soc, char *line, size_t line_size, int timeout);
+/* Split a "user[:pass]@" prefix (end = jump_identification result) into
+   bounded, NUL-terminated user/pass buffers, truncating to fit. */
+void ftp_split_userpass(const char *src, const char *end, char *user,
+                        size_t user_size, char *pass, size_t pass_size);
 T_SOC get_datasocket(char *to_send, size_t to_send_size);
 int stop_ftp(lien_back * back);
 char *linejmp(char *line);

src/htsjava.c

@@ -63,6 +63,9 @@ Please visit our Website: http://www.httrack.com
 /* This file */
 #include "htsjava.h"
 
+/* calloct/freet wrappers */
+#include "htssafe.h"
+
 static int reverse_endian(void) {
   int endian = 1;
 
@@ -204,7 +207,16 @@ static int hts_parse_java(t_hts_callbackarg * carg, httrackp * opt,
         return 0;
       }
 
-      tab = (RESP_STRUCT *) calloc(header.count, sizeof(RESP_STRUCT));
+      /* A constant-pool entry is >= 1 byte on disk; reject a count exceeding
+         the file size (hostile .class ~68 MB alloc DoS). */
+      if (!hts_count_fits(header.count, (LLint) fsize(file))) {
+        fclose(fpout);
+        sprintf(str->err_msg,
+                "Invalid constant pool count %u (file len " LLintP ")",
+                (unsigned) header.count, (LLint) fsize(file));
+        return 0;
+      }
+      tab = (RESP_STRUCT *) calloct(header.count, sizeof(RESP_STRUCT));
       if (!tab) {
         sprintf(str->err_msg, "Unable to alloc %d bytes",
                 (int) sizeof(RESP_STRUCT));
@@ -230,7 +242,7 @@ static int hts_parse_java(t_hts_callbackarg * carg, httrackp * opt,
           } else {              // ++ une erreur est survenue!
             if (strnotempty(str->err_msg) == 0)
               strcpy(str->err_msg, "Internal readtable error");
-            free(tab);
+            freet(tab);
             if (fpout) {
               fclose(fpout);
               fpout = NULL;
@@ -288,7 +300,7 @@ static int hts_parse_java(t_hts_callbackarg * carg, httrackp * opt,
 #if JAVADEBUG
       printf("end\n");
 #endif
-      free(tab);
+      freet(tab);
       if (fpout) {
         fclose(fpout);
         fpout = NULL;

src/htssafe.h

@@ -456,6 +456,13 @@ static HTS_INLINE HTS_UNUSED const char *htsbuff_str(const htsbuff *b) {
   return b->buf;
 }
 
+/** True if 'count' records of >= 1 byte each fit in 'available' bytes; guards
+    an attacker-controlled count driving a large allocation. */
+static HTS_INLINE HTS_UNUSED hts_boolean hts_count_fits(size_t count,
+                                                        LLint available) {
+  return (available >= 0 && (LLint) count <= available) ? HTS_TRUE : HTS_FALSE;
+}
+
 /* Thin aliases over the libc allocator/memcpy (historical "t" suffix); no
    added bounds checking. freet() also NULLs the freed pointer and tolerates
    NULL. memcpybuff() despite the name is a raw memcpy: the caller owns the

src/htsselftest.c

@@ -50,6 +50,7 @@ Please visit our Website: http://www.httrack.com
 #include "htsdns_selftest.h"
 #include "htscharset.h"
 #include "htsencoding.h"
+#include "htsftp.h"
 #include "htsmd5.h"
 #if HTS_USEZLIB
 #include "htszlib.h"
@@ -61,6 +62,10 @@ Please visit our Website: http://www.httrack.com
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#ifndef _WIN32
+#include <sys/socket.h>
+#include <unistd.h>
+#endif
 
 /* very minimalistic internal tests */
 static void basic_selftests(void) {
@@ -1769,6 +1774,75 @@ static int st_robots(httrackp *opt, int argc, char **argv) {
   return 0;
 }
 
+/* get_ftp_line must bound a hostile, CRLF-less reply into its internal
+   1024-byte buffer; ASan turns the pre-fix overflow into an abort here. */
+#ifndef _WIN32
+static int st_ftpline(httrackp *opt, int argc, char **argv) {
+  int sv[2];
+  char line[2048];
+  char flood[4096];
+
+  (void) opt;
+  (void) argc;
+  (void) argv;
+  memset(flood, 'x', sizeof(flood));
+  assertf(socketpair(AF_UNIX, SOCK_STREAM, 0, sv) == 0);
+  assertf(write(sv[1], "220 ", 4) == 4); // valid 3-digit code
+  assertf(write(sv[1], flood, sizeof(flood)) == (ssize_t) sizeof(flood));
+  assertf(write(sv[1], "\r\n", 2) == 2); // end the line so we return
+  close(sv[1]);
+  line[0] = '\0';
+  get_ftp_line(sv[0], line, sizeof(line), 5);
+  close(sv[0]);
+  printf("ftp-line self-test OK (bounded %d-byte reply)\n",
+         (int) sizeof(flood));
+  return 0;
+}
+#endif
+
+/* ftp_split_userpass: well-formed split, plus a hostile over-long userinfo
+   that pre-fix overran user[256]/pass[256]. */
+static int st_ftpuser(httrackp *opt, int argc, char **argv) {
+  char user[256], pass[256];
+  char in[1200];
+
+  (void) opt;
+  (void) argc;
+  (void) argv;
+  {
+    const char ok[] = "bob:secret@host/f"; // '@' at index 10
+
+    ftp_split_userpass(ok, ok + 11, user, sizeof(user), pass, sizeof(pass));
+    assertf(strcmp(user, "bob") == 0);
+    assertf(strcmp(pass, "secret") == 0);
+  }
+  memset(in, 'u', 400);
+  in[400] = ':';
+  memset(in + 401, 'p', 400);
+  in[801] = '@';
+  in[802] = '\0';
+  ftp_split_userpass(in, in + 802, user, sizeof(user), pass, sizeof(pass));
+  assertf(strlen(user) == sizeof(user) - 1);
+  assertf(strlen(pass) == sizeof(pass) - 1);
+  printf("ftp-userpass self-test OK\n");
+  return 0;
+}
+
+/* hts_count_fits caps the .class constant-pool entry count to the file size,
+   rejecting the ~68 MB-per-file calloc DoS. */
+static int st_java(httrackp *opt, int argc, char **argv) {
+  (void) opt;
+  (void) argc;
+  (void) argv;
+  assertf(hts_count_fits(10, 1000) == HTS_TRUE);
+  assertf(hts_count_fits(0, 10) == HTS_TRUE);
+  assertf(hts_count_fits(65535, 10) == HTS_FALSE);
+  assertf(hts_count_fits(1, 0) == HTS_FALSE);
+  assertf(hts_count_fits(1, -1) == HTS_FALSE);
+  printf("java constant-pool cap self-test OK\n");
+  return 0;
+}
+
 /* ------------------------------------------------------------ */
 /* Registry: name -> handler, with a usage hint and a one-line description. */
 /* ------------------------------------------------------------ */
@@ -1829,6 +1903,12 @@ static const struct selftest_entry {
      "Accept-Encoding advertises gzip+deflate, both decode", st_acceptencoding},
     {"robots", "", "robots.txt RFC 9309 Allow/Disallow precedence self-test",
      st_robots},
+#ifndef _WIN32
+    {"ftp-line", "", "get_ftp_line bounds a hostile FTP reply line",
+     st_ftpline},
+#endif
+    {"ftp-userpass", "", "ftp_split_userpass bounds URL userinfo", st_ftpuser},
+    {"java", "", "java .class constant-pool count cap self-test", st_java},
 };
 
 static void list_selftests(void) {

tests/01_engine-ftp-line.test

@@ -0,0 +1,7 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+# get_ftp_line bounds a hostile CRLF-less FTP reply into its 1024-byte buffer.
+httrack -O /dev/null -#test=ftp-line run | grep -q "ftp-line self-test OK"

tests/01_engine-ftp-userpass.test

@@ -0,0 +1,7 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+# ftp_split_userpass bounds an over-long user:pass@ from a hostile ftp:// URL.
+httrack -O /dev/null -#test=ftp-userpass run | grep -q "ftp-userpass self-test OK"

tests/01_engine-java.test

@@ -0,0 +1,7 @@
+#!/bin/bash
+#
+
+set -euo pipefail
+
+# .class constant-pool count is capped to the file size (calloc DoS).
+httrack -O /dev/null -#test=java run | grep -q "java constant-pool cap self-test OK"

tests/Makefile.am

@@ -35,10 +35,13 @@ TESTS = \
 	01_engine-entities.test \
 	01_engine-filelist.test \
 	01_engine-filter.test \
+	01_engine-ftp-line.test \
+	01_engine-ftp-userpass.test \
 	01_engine-hashtable.test \
 	01_engine-idna.test \
 	01_engine-escape-room.test \
 	01_engine-inplace-escape.test \
+	01_engine-java.test \
 	01_engine-makeindex.test \
 	01_engine-mime.test \
 	01_engine-parse.test \