Resolve full path of pcap which starts with '~'

src/fileutil.c

@@ -15,29 +15,93 @@
  */
 
 #include <defines.h>
+#include <errno.h>
+#include <pwd.h>                /* for getpwnam_r() */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 extern char* scenario_path;
 
+int expand_user_path(const char* path, char* expanded_home_path /*The buffer*/, size_t buflen)
+{
+    if (path[0] != '~') {                       /* We have nothing to expand here */
+        return 1;
+    }
+
+    memset(expanded_home_path, '\0', buflen);
+    char* home_dir = NULL;
+
+    if (path[1] == '\0' || path[1] == '/') {                                                    /* '~/path' case */
+        home_dir = getenv("HOME");
+        if (home_dir == NULL) {
+            home_dir = getenv("USERPROFILE");
+        } else {
+            snprintf(expanded_home_path, buflen - 1, "%s%s", home_dir, path + 1);
+        }
+    } else {
+        const char* first_slash = strchr(path, '/');                                            /* substring starting from '/' */
+        const size_t linux_username_limit = 32;                                                 /* As of now */
+        char* username = NULL;
+        if ((first_slash != NULL) && ((first_slash - (path + 1)) <= linux_username_limit)) {    /* '~someuser/blah' case */
+            username = strndup(path + 1, first_slash - (path + 1));
+        } else {                                                                                /* '~someuser' case, there is no file, just username */
+            return -1;
+        }
+
+        struct passwd pwd;
+        struct passwd* result;
+        const size_t bufsize  = sysconf(_SC_GETPW_R_SIZE_MAX) +1;
+        char* buffer = malloc(bufsize * sizeof(char));
+        int retcode = getpwnam_r(username, &pwd, buffer, bufsize - 1, &result);
+        free(username);
+        free(buffer);
+        if (result == NULL) {
+            if (retcode != 0) {
+                errno = retcode;
+            }
+            WARNING_NO("Unable to resolve home path for [%s]\n", path);
+            return -1;
+        } else {
+            home_dir = result->pw_dir;
+        }
+
+        if (home_dir != NULL) {
+            if (first_slash != NULL) {                                                      /* '~username/path' case */
+                snprintf(expanded_home_path, buflen - 1, "%s%s", home_dir, first_slash);
+            } else {                                                                        /* '~username' case should be eliminated above, but just in case it is modified in future*/
+                return -1;
+            }
+        }
+    }
+
+    return 1;
+}
+
 char* find_file(const char* filename)
 {
-    char *fullpath;
-    if (filename[0] == '/' || !*scenario_path) {
-        return strdup(filename);
+    char tmppath[MAX_PATH];
+    tmppath[0] = '\0';
+    const char* filepathptr = tmppath;
+    if ((expand_user_path(filename, tmppath, sizeof(tmppath)) == -1) || (tmppath[0] == '\0')) {     /* we couldn't expand path, or buffer is still empty */
+        filepathptr = filename;
+    }
+
+    if (filepathptr[0] == '/' || !*scenario_path) {
+        return strdup(filepathptr);
     }
 
-    fullpath = malloc(MAX_PATH);
-    snprintf(fullpath, MAX_PATH, "%s%s", scenario_path, filename);
+    size_t len = strlen(scenario_path) + strlen(filepathptr) + 1;
+    char* fullpath = malloc(len);
+    snprintf(fullpath, len, "%s%s", scenario_path, filepathptr);
 
     if (access(fullpath, R_OK) < 0) {
         free(fullpath);
         WARNING("SIPp now prefers looking for pcap/rtpstream files next to the scenario. "
                 "%s couldn't be found next to the scenario, falling back to "
-                "using the current working directory", filename);
-        return strdup(filename);
+                "using the current working directory", filepathptr);
+        return strdup(filepathptr);
     }
 
     return fullpath;