Fixed compiler warnings and rewrote documentation for meson.

README.md

@@ -1,8 +1,7 @@
 # exim-encrypt-dlfunc
 
 This library injects functions for string encryption and decryption into [exim4](https://www.exim.org/). It is basically
-a little glue code to parts of the [libsodium library](https://github.com/jedisct1/libsodium)
-to exim at runtime.
+glue code that exports certain parts of the [libsodium library](https://github.com/jedisct1/libsodium) to exim at runtime.
 
 ## Installation
 
@@ -11,37 +10,31 @@ These instructions are currently only tested on Debian Linux.
 1. Install development tools and libsodium development files:
 
 ```shell
-apt-get install build-essential exim4-dev libsodium-dev
+apt-get build-essential exim4-dev libsodium-dev meson pkg-config openssl exim4-daemon-heavy
 ```
 
 2. Clone this repository:
 
 ```shell
 git clone https://git.scc.kit.edu/mail/exim-encrypt-dlfunc.git
-cd exim-encrypt-dlfunc/src
+cd exim-encrypt-dlfunc
 ```
 
-3. Build `genkey` if needed (see below for an explanation):
+3. Build and test everything:
 
 ```shell
-make genkey
-```
-
-4. Build the library:
-
-```shell
-make
+meson build # run only once
+cd build
+ninja
 ```
 
 5. Copy to final destination (feel free to pick another place than `/usr/local/lib/`):
 
-```shell
-sudo install --group=Debian-exim --owner=Debian-exim libexim-encrypt-dlfunc.so /usr/local/lib/
-```
+TBD…
 
-6. Ensure you have the correct exim flavor:
+6. Ensure you have the correct exim build:
 
-   Not every flavor of exim is able to load libraries at runtime. Please refer to the
+   Not every build of exim is able to load libraries at runtime. Please refer to the
    [documentation](https://www.exim.org/exim-html-current/doc/html/spec_html/ch-string_expansions.html)
    of the `${dlfunc{…}}` function for details. exim from the debian package `exim4-daemon-heavy` meets all the
    requirements.
@@ -63,11 +56,11 @@ Public key encryption that uses a key pair that needs to be created beforehand:
 * `sodium_crypto_box_seal_open(private key, public key, ciphertext) → cleartext`
 
 The second pair needs a proper key pair in the correct format. This is what the
-`genkey` utility is for. Simply run it once to generate a pair. Be aware that every invocation will overwrite the
-previous key pair without confirmation! Please save both parts in a safe place before proceeding.
+`generate_encryption_keys` utility is for. Simply run it once to generate a pair. Be aware that every invocation will
+overwrite the previous key pair without confirmation! Please save both parts in a safe place before proceeding.
 
 ```shell
-$ ./genkey 
+$ ./generate_encryption_keys 
 === Creating cryptobox key pair ===
   Wrote »cryptobox_recipient_pk_exim.conf«
   Wrote »cryptobox_recipient_pk.raw«
@@ -75,8 +68,8 @@ $ ./genkey
   Wrote »cryptobox_recipient_sk.raw
 ```
 
-The `*_exim.conf` files contain the keys in a format that can simply be pasted into
-`exim.conf` (the first line contains the key as C code and can usually be discarded):
+The `*_exim.conf` files contain the keys in a format that can simply be used in
+`exim.conf` (the first line contains the key as a C code comment and can usually be discarded):
 
 ```shell
 $ cat cryptobox_recipient_pk_exim.conf

src/Makefile

@@ -1,19 +0,0 @@
-CC=gcc
-CFLAGS=-I/usr/include/exim4 -g
-LDFLAGS=-lsodium
-LDFLAGS_LIB=-fpic -shared
-
-.PHONY: clean all
-
-.DEFAULT_GOAL := all
-
-libexim-encrypt-dlfunc.so: libexim-encrypt-dlfunc.c
-	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS) $(LDFLAGS_LIB)
-
-genkey: genkey.c
-	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
-
-clean:
-	rm -f libexim-encrypt-dlfunc.so genkey
-
-all: libexim-encrypt-dlfunc.so genkey

src/generate_encryption_keys.c

@@ -5,7 +5,7 @@
 bool key_contains_zero(unsigned char *key, unsigned int keylen)
 {
 	bool has_zero = false;
-	for (int i = 0; i < keylen; i++) {
+	for (unsigned int i = 0; i < keylen; i++) {
 		if (key[i] == 0) {
 			has_zero = true;
 		}
@@ -18,7 +18,7 @@ dump_key_as_c_code(FILE * f, const char *name, unsigned char *key,
 		   unsigned int keylen)
 {
 	fprintf(f, "const unsigned char %s[] = { ", name);
-	for (int i = 0; i < keylen; i++) {
+	for (unsigned int i = 0; i < keylen; i++) {
 		fprintf(f, "0x%02x", key[i]);
 		if (i < keylen - 1) {
 			fprintf(f, ", ");
@@ -34,7 +34,7 @@ dump_key_as_exim_config(FILE * f, const char *name, unsigned char *key,
 {
     // write a comment with C variable declaration
     fprintf(f, "# const unsigned char %s[%d] = { ", name, keylen);
-    for (int i = 0; i < keylen; i++) {
+    for (unsigned int i = 0; i < keylen; i++) {
         fprintf(f, "0x%02x", key[i]);
         if (i < keylen - 1) {
             fprintf(f, ", ");
@@ -132,7 +132,7 @@ void create_secretbox_key(const char *filebase, const char *varname) {
     write_key_files(key_filename, key_varname, key, crypto_secretbox_KEYBYTES);
 }
 
-int main(int argc, char *argv[]) {
+int main(void) {
     if (sodium_init() < 0) {
         fputs("Unable to initialize libsodium", stderr);
         exit(128);

src/meson.build

@@ -2,7 +2,7 @@ configure_file(
 		      output: 'config.h',
 		      configuration: conf_data)
 
-executable('genkey', 'genkey.c', dependencies : [ sodium_deps ] )
+executable('generate_encryption_keys', 'generate_encryption_keys.c', dependencies : [ sodium_deps ] )
 
 shared_library('exim-encrypt-dlfunc', 'libexim-encrypt-dlfunc.c',
 				      dependencies : [ sodium_deps ],