apply fixes from https://github.com/borrougagnou/maintenance-termbin/

fiche.c

@@ -33,7 +33,9 @@ $ cat fiche.c | nc localhost 9999
 #include <stdlib.h>
 #include <string.h>
 
+#include <errno.h>
 #include <pwd.h>
+#include <grp.h>
 #include <time.h>
 #include <unistd.h>
 #include <pthread.h>
@@ -105,10 +107,9 @@ static void dispatch_connection(int socket, Fiche_Settings *settings);
  */
 static void *handle_connection(void *args);
 
-char* replace_substr(const char *str, const char *old, const char *new);
-
 // Server-related utils
 
+
 /**
  * @brief Generates a slug that will be used for paste creation
  * @warning output has to be freed after using!
@@ -128,7 +129,7 @@ static void generate_slug(char **output, uint8_t length, uint8_t extra_length);
 
 /**
  * @brief Creates a directory at requested path using requested slug
- * @returns 0 if succeded, 1 if failed or dir already existed
+ * @returns 0 if succeeded, 1 if failed or dir already existed
  *
  * @arg output_dir root directory for all pastes
  * @arg slug directory name for a particular paste
@@ -253,19 +254,29 @@ int fiche_run(Fiche_Settings settings) {
         }
     }
 
-    // Check if log file is writable (if set)
+    // Check if log file is valid and writable (if set)
     if ( settings.log_file_path ) {
 
-        // Create log file if it doesn't exist
+        struct stat log_file_st;
-        FILE *f = fopen(settings.log_file_path, "a+");
+        memset(&log_file_st, 0, sizeof(struct stat));
-        fclose(f);
 
-        // Then check if it's accessible
+        if ( stat(settings.log_file_path, &log_file_st) == 0 ) {
-        if ( access(settings.log_file_path, W_OK) != 0 ) {
+            // Is the log file a regular file?
-            print_error("Log file not writable!");
+            if ( !S_ISREG(log_file_st.st_mode) ) {
-            return -1;
+                print_error("Log file is not valid!");
+                return -1;
+            }
+
+            // Can we write to it?
+            if ( access(settings.log_file_path, W_OK) != 0 ) {
+                print_error("Log file is not writable!");
+                return -1;
+            }
+        } else {
+            // Log file doesn't exist - create it.
+            FILE *f = fopen(settings.log_file_path, "a+");
+            fclose(f);
         }
-
     }
 
     // Try to set domain name
@@ -279,7 +290,7 @@ int fiche_run(Fiche_Settings settings) {
 
     // Perform final cleanup
 
-    // This is allways allocated on the heap
+    // This is always allocated on the heap
     free(settings.domain);
 
     return 0;
@@ -405,22 +416,38 @@ static int perform_user_change(const Fiche_Settings *settings) {
     // Get user details
     const struct passwd *userdata = getpwnam(settings->user_name);
 
-    const int uid = userdata->pw_uid;
+    if (!userdata) {
-    const int gid = userdata->pw_gid;
-
-    if (uid == -1 || gid == -1) {
         print_error("Could find requested user: %s!", settings->user_name);
         return -1;
     }
 
+    const uid_t uid = userdata->pw_uid;
+    const gid_t gid = userdata->pw_gid;
+
     if (setgid(gid) != 0) {
-        print_error("Couldn't switch to requested user: %s!", settings->user_name);
+        print_error("Couldn't switch to requested group for user: %s!", settings->user_name);
+    }
+
+    // Check if gid change actually happened.
+    if (getgid() != gid) {
+        print_error("Couldn't switch to requested group for user: %s!", settings->user_name);
+    }
+
+    // We must re-initialize supplementary groups to avoid inheriting
+    // root's supplementary groups.
+    if (initgroups(settings->user_name, gid) != 0) {
+        print_error("Couldn't initialize supplementary groups for user: %s!", settings->user_name);
     }
 
     if (setuid(uid) != 0) {
         print_error("Couldn't switch to requested user: %s!", settings->user_name);
     }
 
+    // Check if uid change actually happened.
+    if (getuid() != uid) {
+        print_error("Couldn't switch to requested user: %s!", settings->user_name);
+    }
+
     print_status("User changed to: %s.", settings->user_name);
 
     return 0;
@@ -442,28 +469,20 @@ static int start_server(Fiche_Settings *settings) {
         return -1;
     }
 
-    // Prepare address and port handler for IPv6
+    // Prepare address and port handler
     struct sockaddr_in6 address;
     address.sin6_family = AF_INET6;
-    address.sin6_addr = in6addr_any;  // Bind to any address, for a specific address use inet_pton
+    inet_pton(AF_INET6, settings->listen_addr, &address.sin6_addr);
     address.sin6_port = htons(settings->port);
 
-    // Convert IPv4 address to IPv6 if needed
-    if (settings->listen_addr) {
-        if (inet_pton(AF_INET6, settings->listen_addr, &address.sin6_addr) != 1) {
-            print_error("Invalid IPv6 address!");
-            return -1;
-        }
-    }
-
     // Bind to port
-    if (bind(s, (struct sockaddr *) &address, sizeof(address)) != 0) {
+    if ( bind(s, (struct sockaddr *) &address, sizeof(address)) != 0) {
         print_error("Couldn't bind to the port: %d!", settings->port);
         return -1;
     }
 
     // Start listening
-    if (listen(s, 128) != 0) {
+    if ( listen(s, 128) != 0 ) {
         print_error("Couldn't start listening on the socket!");
         return -1;
     }
@@ -480,7 +499,7 @@ static int start_server(Fiche_Settings *settings) {
     // Give some time for all threads to finish
     // NOTE: this code is reached only in testing environment
     // There is currently no way to kill the main thread from any thread
-    // Something like this can be done for testing purpouses:
+    // Something like this can be done for testing purposes:
     // int i = 0;
     // while (i < 3) {
     //     dispatch_connection(s, settings);
@@ -498,13 +517,14 @@ static void dispatch_connection(int socket, Fiche_Settings *settings) {
     // Create address structs for this socket
     struct sockaddr_in6 address;
     socklen_t addlen = sizeof(address);
- 
+
-   // Accept a connection and get a new socket id
+    // Accept a connection and get a new socket id
     const int s = accept(socket, (struct sockaddr *) &address, &addlen);
     if (s < 0 ) {
         print_error("Error on accepting connection!");
         return;
     }
+
     // Set timeout for accepted socket
     const struct timeval timeout = { 5, 0 };
 
@@ -528,70 +548,42 @@ static void dispatch_connection(int socket, Fiche_Settings *settings) {
 
     // Spawn a new thread to handle this connection
     pthread_t id;
+    pthread_attr_t attr;
 
-    if ( pthread_create(&id, NULL, &handle_connection, c) != 0 ) {
+    if ( (errno = pthread_attr_init(&attr)) ||
+         (errno = pthread_attr_setstacksize(&attr, 128*1024)) ||
+         (errno = pthread_create(&id, &attr, &handle_connection, c)) ) {
+        pthread_attr_destroy(&attr);
         print_error("Couldn't spawn a thread!");
         return;
     }
 
-    // Detach thread if created succesfully
+    pthread_attr_destroy(&attr);
+
+    // Detach thread if created successfully
     // TODO: consider using pthread_tryjoin_np
     pthread_detach(id);
 
 }
 
 
-char* replace_substr(const char *str, const char *old, const char *new) {
-    char *result;
-    int i, count = 0;
-    int newlen = strlen(new);
-    int oldlen = strlen(old);
-
-    // Counting the number of times the old substring occurs in the string
-    for (i = 0; str[i] != '\0'; i++) {
-        if (strstr(&str[i], old) == &str[i]) {
-            count++;
-            i += oldlen - 1;
-        }
-    }
-
-    // Allocating memory for the new string
-    result = (char *)malloc(i + count * (newlen - oldlen) + 1);
-
-    i = 0;
-    while (*str) {
-        // Compare the substring with the result
-        if (strstr(str, old) == str) {
-            strcpy(&result[i], new);
-            i += newlen;
-            str += oldlen;
-        } else {
-            result[i++] = *str++;
-        }
-    }
-
-    result[i] = '\0';
-    return result;
-}
-
 static void *handle_connection(void *args) {
-
+    char *slug = NULL;
+    uint8_t *buffer = NULL;
 
     // Cast args to it's previous type
     struct fiche_connection *c = (struct fiche_connection *) args;
-    //struct sockaddr_in6 *addr = (struct sockaddr_in6 *)&c->address;
 
-    char ipstr[INET6_ADDRSTRLEN];
+    // Get client's IP
-    char *ip;
+    char ip_str[INET6_ADDRSTRLEN];
-
+    const char *ip = inet_ntop(AF_INET6, &c->address.sin6_addr, ip_str, INET6_ADDRSTRLEN);
-    struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&c->address;
-    inet_ntop(AF_INET6, &addr6->sin6_addr, ipstr, sizeof(ipstr));
-    ip = replace_substr(ipstr, "::ffff:", "");
 
     // Get client's hostname
     char hostname[1024];
+
     if (getnameinfo((struct sockaddr *)&c->address, sizeof(c->address),
             hostname, sizeof(hostname), NULL, 0, 0) != 0 ) {
+
         // Couldn't resolve a hostname
         strcpy(hostname, "n/a");
     }
@@ -601,30 +593,37 @@ static void *handle_connection(void *args) {
         char date[64];
         get_date(date);
         print_status("%s", date);
+
         print_status("Incoming connection from: %s (%s).", ip, hostname);
     }
 
     // Create a buffer
-    uint8_t buffer[c->settings->buffer_len];
+    buffer = calloc(c->settings->buffer_len, 1);
-    memset(buffer, 0, c->settings->buffer_len);
+    if (!buffer) {
+        print_error("Couldn't allocate the buffer!");
+        print_separator();
 
-    const int r = recv(c->socket, buffer, sizeof(buffer), MSG_WAITALL);
+        goto exit;
+    }
+
+    const int r = recv(c->socket, buffer, c->settings->buffer_len, MSG_WAITALL);
     if (r <= 0) {
         print_error("No data received from the client!");
         print_separator();
 
-        // Close the socket
+        goto exit;
-        close(c->socket);
-
-        // Cleanup
-        free(c);
-        free(ip);
-        pthread_exit(NULL);
-
-        return 0;
     }
 
-    char *slug;
+    // - Check if request was performed with a known protocol
+    // TODO
+
+    // - Check if on whitelist
+    // TODO
+
+    // - Check if on banlist
+    // TODO
+
+    // Generate slug and use it to create an url
     uint8_t extra = 0;
 
     do {
@@ -648,12 +647,7 @@ static void *handle_connection(void *args) {
             print_error("Couldn't generate a valid slug!");
             print_separator();
 
-            // Cleanup
+            goto exit;
-            close(c->socket);
-            free(c);
-            free(slug);
-            pthread_exit(NULL);
-            return NULL;
         }
 
     }
@@ -665,12 +659,7 @@ static void *handle_connection(void *args) {
         print_error("Couldn't generate a slug!");
         print_separator();
 
-        close(c->socket);
+        goto exit;
-
-        // Cleanup
-        free(c);
-        pthread_exit(NULL);
-        return NULL;
     }
 
 
@@ -679,13 +668,7 @@ static void *handle_connection(void *args) {
         print_error("Couldn't save a file!");
         print_separator();
 
-        close(c->socket);
+        goto exit;
-
-        // Cleanup
-        free(c);
-        free(slug);
-        pthread_exit(NULL);
-        return NULL;
     }
 
     // Write a response to the user
@@ -707,15 +690,15 @@ static void *handle_connection(void *args) {
     // TODO: log unsuccessful and rejected connections
     log_entry(c->settings, ip, hostname, slug);
 
+exit:
     // Close the connection
     close(c->socket);
 
     // Perform cleanup of values used in this thread
+    free(buffer);
     free(slug);
     free(c);
 
-    pthread_exit(NULL);
-
     return NULL;
 }