fix: refactoring and portability — issues #61, #51, #52

src/shared/compression.c

@@ -66,8 +66,16 @@ Data* data_decompress(Data* compressed_data) {
     return NULL;
   }
 
-  size_t buf_size =
-      (!ZSTD_isError(dst_size) && dst_size > 0) ? (size_t)dst_size : INITIAL_DECOMPRESS_BUF_SIZE;
+  size_t buf_size = INITIAL_DECOMPRESS_BUF_SIZE;
+  if (!ZSTD_isError(dst_size) && dst_size > 0) {
+    if (dst_size > SIZE_MAX) {
+      log_message(LOG_LEVEL_ERROR,
+                  "Decompressed size %llu exceeds addressable memory, using fallback buffer",
+                  dst_size);
+    } else {
+      buf_size = (size_t)dst_size;
+    }
+  }
   Data* uncompressed_data = data_create_empty(buf_size);
   if (!uncompressed_data) {
     log_message(LOG_LEVEL_ERROR, "Failed to allocate decompression buffer");

src/shared/data.c

@@ -3,6 +3,8 @@
 #include "stdlib.h"
 
 Data* data_create_empty(size_t data_size) {
+  if (data_size == 0)
+    data_size = 1;
   void* data = malloc(data_size);
   if (data == NULL) {
     log_message(LOG_LEVEL_ERROR, "Could not allocate memory for empty data");

src/shared/data.h

@@ -1,7 +1,7 @@
 #ifndef DATA_H
 #define DATA_H
 
-#include "stdlib.h"
+#include <stdlib.h>
 
 typedef struct {
   void* data;

src/shared/log.c

@@ -10,7 +10,7 @@ void set_log_level(LogLevel level) {
   current_log_level = level;
 }
 
-void log_message(LogLevel log_level, char* format, ...) {
+void log_message(LogLevel log_level, const char* format, ...) {
   if (log_level < current_log_level)
     return;
   time_t now = time(NULL);

src/shared/log.h

@@ -3,7 +3,7 @@
 
 typedef enum { LOG_LEVEL_DEBUG, LOG_LEVEL_INFO, LOG_LEVEL_WARNING, LOG_LEVEL_ERROR } LogLevel;
 
-void log_message(LogLevel log_level, char* message, ...);
+void log_message(LogLevel log_level, const char* message, ...);
 void set_log_level(LogLevel level);
 
 #endif

src/shared/metadata.c

@@ -4,6 +4,7 @@
 #include "protocol.h"
 #include <errno.h>
 #include <fcntl.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -16,16 +17,21 @@ void metadata_to_buf(char** buf, const FileMetadata* m) {
   *buf += sizeof(int);
   if (m == NULL)
     return;
-  memcpy(*buf, &m->mode, sizeof(mode_t));
-  *buf += sizeof(mode_t);
-  memcpy(*buf, &m->uid, sizeof(uid_t));
-  *buf += sizeof(uid_t);
-  memcpy(*buf, &m->gid, sizeof(gid_t));
-  *buf += sizeof(gid_t);
-  memcpy(*buf, &m->mtime_sec, sizeof(time_t));
-  *buf += sizeof(time_t);
-  memcpy(*buf, &m->mtime_nsec, sizeof(long));
-  *buf += sizeof(long);
+  int32_t tmp32 = (int32_t)m->mode;
+  memcpy(*buf, &tmp32, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  tmp32 = (int32_t)m->uid;
+  memcpy(*buf, &tmp32, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  tmp32 = (int32_t)m->gid;
+  memcpy(*buf, &tmp32, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  int64_t tmp64 = (int64_t)m->mtime_sec;
+  memcpy(*buf, &tmp64, sizeof(int64_t));
+  *buf += sizeof(int64_t);
+  tmp64 = (int64_t)m->mtime_nsec;
+  memcpy(*buf, &tmp64, sizeof(int64_t));
+  *buf += sizeof(int64_t);
 }
 
 FileMetadata* metadata_from_buf(char** buf) {
@@ -35,16 +41,23 @@ FileMetadata* metadata_from_buf(char** buf) {
   if (!present)
     return NULL;
   FileMetadata* m = malloc(sizeof(FileMetadata));
-  memcpy(&m->mode, *buf, sizeof(mode_t));
-  *buf += sizeof(mode_t);
-  memcpy(&m->uid, *buf, sizeof(uid_t));
-  *buf += sizeof(uid_t);
-  memcpy(&m->gid, *buf, sizeof(gid_t));
-  *buf += sizeof(gid_t);
-  memcpy(&m->mtime_sec, *buf, sizeof(time_t));
-  *buf += sizeof(time_t);
-  memcpy(&m->mtime_nsec, *buf, sizeof(long));
-  *buf += sizeof(long);
+  int32_t tmp32;
+  int64_t tmp64;
+  memcpy(&tmp32, *buf, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  m->mode = (mode_t)tmp32;
+  memcpy(&tmp32, *buf, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  m->uid = (uid_t)tmp32;
+  memcpy(&tmp32, *buf, sizeof(int32_t));
+  *buf += sizeof(int32_t);
+  m->gid = (gid_t)tmp32;
+  memcpy(&tmp64, *buf, sizeof(int64_t));
+  *buf += sizeof(int64_t);
+  m->mtime_sec = (time_t)tmp64;
+  memcpy(&tmp64, *buf, sizeof(int64_t));
+  *buf += sizeof(int64_t);
+  m->mtime_nsec = (long)tmp64;
   return m;
 }
 
@@ -54,12 +67,17 @@ bool metadata_send(int file_descriptor, FileMetadata* m) {
     return send_n_data(file_descriptor, &zero, sizeof(int));
   }
   int present = 1;
+  int32_t mode_i32 = (int32_t)m->mode;
+  int32_t uid_i32 = (int32_t)m->uid;
+  int32_t gid_i32 = (int32_t)m->gid;
+  int64_t mtime_sec_i64 = (int64_t)m->mtime_sec;
+  int64_t mtime_nsec_i64 = (int64_t)m->mtime_nsec;
   return send_n_data(file_descriptor, &present, sizeof(int)) &&
-         send_n_data(file_descriptor, &m->mode, sizeof(mode_t)) &&
-         send_n_data(file_descriptor, &m->uid, sizeof(uid_t)) &&
-         send_n_data(file_descriptor, &m->gid, sizeof(gid_t)) &&
-         send_n_data(file_descriptor, &m->mtime_sec, sizeof(time_t)) &&
-         send_n_data(file_descriptor, &m->mtime_nsec, sizeof(long));
+         send_n_data(file_descriptor, &mode_i32, sizeof(int32_t)) &&
+         send_n_data(file_descriptor, &uid_i32, sizeof(int32_t)) &&
+         send_n_data(file_descriptor, &gid_i32, sizeof(int32_t)) &&
+         send_n_data(file_descriptor, &mtime_sec_i64, sizeof(int64_t)) &&
+         send_n_data(file_descriptor, &mtime_nsec_i64, sizeof(int64_t));
 }
 
 FileMetadata* metadata_receive(int file_descriptor, int* ok) {
@@ -80,16 +98,23 @@ FileMetadata* metadata_receive(int file_descriptor, int* ok) {
       *ok = 0;
     return NULL;
   }
-  if (!receive_n_data(file_descriptor, &m->mode, sizeof(mode_t)) ||
-      !receive_n_data(file_descriptor, &m->uid, sizeof(uid_t)) ||
-      !receive_n_data(file_descriptor, &m->gid, sizeof(gid_t)) ||
-      !receive_n_data(file_descriptor, &m->mtime_sec, sizeof(time_t)) ||
-      !receive_n_data(file_descriptor, &m->mtime_nsec, sizeof(long))) {
+  int32_t mode_i32, uid_i32, gid_i32;
+  int64_t mtime_sec_i64, mtime_nsec_i64;
+  if (!receive_n_data(file_descriptor, &mode_i32, sizeof(int32_t)) ||
+      !receive_n_data(file_descriptor, &uid_i32, sizeof(int32_t)) ||
+      !receive_n_data(file_descriptor, &gid_i32, sizeof(int32_t)) ||
+      !receive_n_data(file_descriptor, &mtime_sec_i64, sizeof(int64_t)) ||
+      !receive_n_data(file_descriptor, &mtime_nsec_i64, sizeof(int64_t))) {
     free(m);
     if (ok)
       *ok = 0;
     return NULL;
   }
+  m->mode = (mode_t)mode_i32;
+  m->uid = (uid_t)uid_i32;
+  m->gid = (gid_t)gid_i32;
+  m->mtime_sec = (time_t)mtime_sec_i64;
+  m->mtime_nsec = (long)mtime_nsec_i64;
   if (ok)
     *ok = 1;
   return m;

src/shared/metadata.h

@@ -3,10 +3,10 @@
 
 #include "file.h"
 #include <stdbool.h>
+#include <stdint.h>
 #include <sys/stat.h>
 
-#define FILE_METADATA_WIRE_SIZE                                                                    \
-  (sizeof(mode_t) + sizeof(uid_t) + sizeof(gid_t) + sizeof(time_t) + sizeof(long))
+#define FILE_METADATA_WIRE_SIZE (sizeof(int32_t) * 3 + sizeof(int64_t) * 2)
 
 void metadata_to_buf(char** buf, const FileMetadata* m);
 FileMetadata* metadata_from_buf(char** buf);

src/shared/protocol.c

@@ -34,11 +34,17 @@ static void bw_throttle(size_t bytes_written) {
   struct timespec now;
   clock_gettime(CLOCK_MONOTONIC, &now);
 
-  long long elapsed_ns =
-      (now.tv_sec - bw_last_refill.tv_sec) * 1000000000LL + (now.tv_nsec - bw_last_refill.tv_nsec);
+  /* Use unsigned long long for intermediate computation to avoid overflow.
+   * sec_diff * 1000000000LL could overflow a signed 64-bit if the elapsed
+   * time is very large; clamp to a safe maximum. */
+  unsigned long long sec_diff = (unsigned long long)(now.tv_sec - bw_last_refill.tv_sec);
+  if (sec_diff > 9223372036ULL)
+    sec_diff = 9223372036ULL;
+  unsigned long long elapsed_ns =
+      sec_diff * 1000000000ULL + (unsigned long long)(now.tv_nsec - bw_last_refill.tv_nsec);
   bw_last_refill = now;
 
-  long long tokens_to_add = (long long)((double)io_bwlimit * elapsed_ns / 1000000000.0);
+  long long tokens_to_add = (long long)((double)io_bwlimit * (double)elapsed_ns / 1000000000.0);
   bw_tokens += tokens_to_add;
   if (bw_tokens > (long long)io_bwlimit)
     bw_tokens = (long long)io_bwlimit;
@@ -74,13 +80,23 @@ bool send_n_data(int file_descriptor, const void* data, size_t data_size) {
     if (io_bwlimit > 0 && chunk > 65536)
       chunk = 65536;
     ssize_t bytes_send;
-    if (io_ssl)
+    if (io_ssl) {
       bytes_send = SSL_write(io_ssl, (const char*)data + total_bytes_send, chunk);
-    else
+      if (bytes_send <= 0) {
+        int err = SSL_get_error(io_ssl, (int)bytes_send);
+        if (err == SSL_ERROR_WANT_WRITE || err == SSL_ERROR_WANT_READ) {
+          // Non-fatal: retry without counting progress
+          continue;
+        }
+        log_message(LOG_LEVEL_ERROR, "Could not send data (SSL error: %d)", err);
+        return false;
+      }
+    } else {
       bytes_send = write(fd, (const char*)data + total_bytes_send, chunk);
-    if (bytes_send <= 0) {
-      log_message(LOG_LEVEL_ERROR, "Could not send data");
-      return false;
+      if (bytes_send <= 0) {
+        log_message(LOG_LEVEL_ERROR, "Could not send data");
+        return false;
+      }
     }
     bw_throttle((size_t)bytes_send);
     total_bytes_send += bytes_send;
@@ -95,18 +111,31 @@ bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
   size_t total_bytes_received = 0;
   while (total_bytes_received < data_size) {
     ssize_t bytes_received;
-    if (io_ssl)
+    if (io_ssl) {
       bytes_received =
           SSL_read(io_ssl, (char*)data + total_bytes_received, data_size - total_bytes_received);
-    else
+      if (bytes_received <= 0) {
+        int err = SSL_get_error(io_ssl, (int)bytes_received);
+        if (err == SSL_ERROR_WANT_READ || err == SSL_ERROR_WANT_WRITE) {
+          // Non-fatal: retry without counting progress
+          continue;
+        }
+        if (bytes_received == 0)
+          log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
+        else
+          log_message(LOG_LEVEL_ERROR, "Could not receive bytes (SSL error: %d)", err);
+        return false;
+      }
+    } else {
       bytes_received =
           read(fd, (char*)data + total_bytes_received, data_size - total_bytes_received);
-    if (bytes_received <= 0) {
-      if (bytes_received == 0)
-        log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
-      else
-        log_message(LOG_LEVEL_ERROR, "Could not receive bytes");
-      return false;
+      if (bytes_received <= 0) {
+        if (bytes_received == 0)
+          log_message(LOG_LEVEL_ERROR, "Connection closed while receiving data");
+        else
+          log_message(LOG_LEVEL_ERROR, "Could not receive bytes");
+        return false;
+      }
     }
     total_bytes_received += bytes_received;
   }
@@ -138,6 +167,10 @@ static const char* status_to_string(Status status) {
 }
 
 bool send_str(int file_descriptor, const char* data) {
+  if (data == NULL) {
+    log_message(LOG_LEVEL_ERROR, "send_str called with NULL data");
+    return false;
+  }
   size_t size = strlen(data);
   if (!send_n_data(file_descriptor, &size, sizeof(size_t)))
     return false;
@@ -151,6 +184,11 @@ char* receive_str(int file_descriptor) {
   size_t size;
   if (!receive_n_data(file_descriptor, &size, sizeof(size_t)))
     return NULL;
+  if (size > MAX_STRING_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "receive_str: size %zu exceeds maximum %zu", size,
+                (size_t)MAX_STRING_SIZE);
+    return NULL;
+  }
   char* data = (char*)malloc(size + 1);
   if (data == NULL)
     return NULL;

src/shared/protocol.h

@@ -5,6 +5,9 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+/* Maximum allowed string size for receive_str (10 MB) */
+#define MAX_STRING_SIZE (10 * 1024 * 1024)
+
 typedef struct ssl_st SSL;
 
 typedef int Status;

src/shared/transport_ssh.c

@@ -124,7 +124,11 @@ Client* client_connect_ssh(const char* destination, int port) {
     else
       snprintf(ssh_user, sizeof(ssh_user), "%s", r.host);
 
-    char* ssh_argv[16];
+    /* Max entries: ssh + 3 options*2 each + -p + port + user + cmd + arg + NULL = 13 */
+    size_t ssh_argv_max = 32;
+    char** ssh_argv = calloc(ssh_argv_max, sizeof(char*));
+    if (ssh_argv == NULL)
+      _exit(1);
     int ac = 0;
     char port_str[16];
     ssh_argv[ac++] = "ssh";
@@ -135,15 +139,24 @@ Client* client_connect_ssh(const char* destination, int port) {
     ssh_argv[ac++] = "-o";
     ssh_argv[ac++] = "ControlPath=~/.cache/fastsync-%r@%h:%p";
     if (port > 0 && port != 22) {
+      if ((size_t)ac + 2 >= ssh_argv_max) {
+        free(ssh_argv);
+        _exit(1);
+      }
       ssh_argv[ac++] = "-p";
       snprintf(port_str, sizeof(port_str), "%d", port);
       ssh_argv[ac++] = port_str;
     }
+    if ((size_t)ac + 3 >= ssh_argv_max) {
+      free(ssh_argv);
+      _exit(1);
+    }
     ssh_argv[ac++] = ssh_user;
     ssh_argv[ac++] = "fastsync-server";
     ssh_argv[ac++] = "--stdio";
     ssh_argv[ac] = NULL;
     execvp("ssh", ssh_argv);
+    free(ssh_argv);
     perror("exec of ssh failed");
     ssize_t wret = write(exec_pipe[1], "x", 1);
     (void)wret;

src/shared/transport_tcp.h

@@ -1,20 +1,23 @@
 #ifndef TRANSPORT_TCP_H
 #define TRANSPORT_TCP_H
 
+#include <netdb.h>
 #include <netinet/in.h>
 #include <stdbool.h>
+#include <sys/socket.h>
 #include <sys/types.h>
 
 typedef struct Server {
-  struct sockaddr_in address;
-  unsigned int address_length;
+  struct sockaddr_storage address;
+  socklen_t address_length;
   int file_descriptor;
+  int port;
   void* ssl_ctx;
 } Server;
 
 typedef struct Client {
-  struct sockaddr_in address;
-  unsigned int address_length;
+  struct sockaddr_storage address;
+  socklen_t address_length;
   int file_descriptor;
   pid_t ssh_child_pid;
   void* ssl;

src/shared/utils.c

@@ -10,19 +10,23 @@
 #include <unistd.h>
 
 bool mkdir_r(const char* path) {
-  char* path_duplicate = malloc(strlen(path) + 1);
+  size_t path_len = strlen(path);
+  char* path_duplicate = malloc(path_len + 1);
   if (!path_duplicate)
     return false;
-  strcpy(path_duplicate, path);
-  char* path_current = (char*)malloc((strlen(path) + 2) * sizeof(char));
+  memcpy(path_duplicate, path, path_len + 1);
+  /* Buffer for building subpaths: path_len + 1 for leading '/' + 1 for null */
+  size_t buf_size = path_len + 2;
+  char* path_current = (char*)malloc(buf_size);
   if (!path_current) {
     free(path_duplicate);
     return false;
   }
-  char* path_current_position = path_current;
+  size_t pos = 0;
   if (path[0] == '/') {
-    strcpy(path_current, "/");
-    path_current_position += 1;
+    path_current[0] = '/';
+    path_current[1] = '\0';
+    pos = 1;
   } else {
     path_current[0] = '\0';
   }
@@ -31,10 +35,16 @@ bool mkdir_r(const char* path) {
   const char* part = strtok_r(path_duplicate, delimiter, &saveptr);
   bool ok = true;
   while (part != NULL) {
-    strcpy(path_current_position, part);
-    path_current_position += strlen(part) * sizeof(char);
-    strcpy(path_current_position, "/");
-    path_current_position += sizeof(char);
+    size_t part_len = strlen(part);
+    if (pos + part_len + 1 >= buf_size) {
+      ok = false;
+      break;
+    }
+    memcpy(path_current + pos, part, part_len);
+    pos += part_len;
+    path_current[pos] = '/';
+    pos++;
+    path_current[pos] = '\0';
     struct stat st;
     if (stat(path_current, &st) != 0) {
       if (mkdir(path_current, 0755) != 0) {