“Transport commit”

src/libexim-encrypt-dlfunc-decrypt-secretbox.c

@@ -0,0 +1,149 @@
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <string.h>
+#include <getopt.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sodium.h>
+
+#define ENVVAR_PASSWORD_NAME "LIBEXIM_PASSWORD"
+
+void print_usage(char * progname) {
+    printf("Usage: %s [OPTIONS]\n\n", progname);
+    printf("Password:\n");
+    printf("  -p, --password PASSWORD    decrypt using PASSWORD\n");
+    printf("  -e, --pass-from-env        read password from environment variable LIBEXIM_PASSWORD\n");
+    printf("\n");
+    printf("Select input:\n");
+    printf("  -c, --input STRING         decrypt contents of STRING\n");
+    printf("  -f, --infile FILE          decrypt contents of the first line of file FILE\n");
+    printf("\n");
+}
+
+typedef enum {
+    NONE = 0,
+    PASSARG = 1,
+    PASSENV = 2,
+    INSTRING = 4,
+    INFILE = 8
+} seen_args;
+
+int main(int argc, char *argv[]) {
+    char* prog_basename = basename(argv[0]);
+    int opt;
+    char *cipherstring;
+    size_t pwlen;
+    char *b64password;
+    char *password_env;
+    int fd;
+    char *endptr;
+
+    seen_args mode = NONE;
+    seen_args input = NONE;
+
+    if (sodium_init() < 0) {
+        fputs("Unable to initialize libsodium", stderr);
+        exit(128);
+    }
+
+    // define arguments
+    const char * shortargs = "p:ef:";
+    static struct option long_options[] = {
+            {"password", required_argument, NULL, 'p'},
+            {"pass-from-env", no_argument, NULL, 'e'},
+            {"infile", required_argument, NULL, 'f'},
+            {0,0,0,0}
+    };
+
+    // parse arguments
+    int long_index = 0;
+    while ((opt = getopt_long(argc, argv,shortargs,
+                              long_options, &long_index )) != -1) {
+        switch (opt) {
+            case 'p':
+                pwlen = strlen(optarg);
+                b64password = malloc(pwlen+1);
+                strncpy(b64password, optarg, pwlen);
+                mode |= PASSARG;
+                break;
+            case 'e':
+                password_env = getenv(ENVVAR_PASSWORD_NAME);
+                if (password_env == NULL) {
+                    fprintf(stderr, "[ERROR] Environment variable %s is undefined.\n\n", ENVVAR_PASSWORD_NAME);
+                }
+                pwlen = strlen(password_env);
+                b64password = malloc(pwlen+1);
+                strncpy(b64password, password_env, pwlen);
+                mode |= PASSENV;
+                break;
+            case 'f':
+                // open file
+                fd = open(optarg, O_RDONLY, (mode_t)0600);
+                if (fd == -1) {
+                    perror("Error opening file");
+                    exit(EXIT_FAILURE);
+                }
+                // get length
+                struct stat fileInfo = {0};
+                if (fstat(fd, &fileInfo) == -1) {
+                    perror("Error getting the file size");
+                    exit(EXIT_FAILURE);
+                }
+                if (fileInfo.st_size == 0) {
+                    fprintf(stderr, "Error: File is empty, nothing to do\n");
+                    exit(EXIT_FAILURE);
+                }
+                // mmap file
+                char *map = mmap(0, fileInfo.st_size, PROT_READ, MAP_SHARED, fd, 0);
+                if (map == MAP_FAILED)
+                {
+                    close(fd);
+                    perror("Error mmapping the file");
+                    exit(EXIT_FAILURE);
+                }
+                // find first line
+                endptr = strchrnul(map, 0x0a);
+
+                size_t cipherstring_len = endptr - map;
+                cipherstring = malloc(cipherstring_len+1);
+                strncpy(cipherstring, map, cipherstring_len);
+
+                // munmap and close file
+                if (munmap(map, fileInfo.st_size) == -1)
+                {
+                    close(fd);
+                    perror("Error un-mmapping the file");
+                    exit(EXIT_FAILURE);
+                }
+                close(fd);
+
+                input |= INFILE;
+                break;
+        }
+    }
+
+    // check if a password was provided
+    if (mode == NONE) {
+            fprintf(stderr, "[ERROR] Please specify a password.\n\n");
+            print_usage(prog_basename);
+            exit(EXIT_FAILURE);
+    }
+
+    // read first non-option argument as ciphertext
+    if (optind < argc) {
+        size_t cipherstring_len = strlen(argv[optind])+1;
+        cipherstring = malloc(cipherstring_len+1);
+        strncpy(cipherstring, argv[optind], cipherstring_len);
+        input |= INSTRING;
+    }
+
+    if (input == NONE) {
+            fprintf(stderr, "[ERROR] Please specify a ciphertext source.\n\n");
+            print_usage(prog_basename);
+            exit(EXIT_FAILURE);
+    }
+    printf("»%s«\n", cipherstring);
+}