Decouple C SSL Option bit flags from Rust version

The OpenSSL "SSL_OP_*" flags are in constant flux between different OpenSSL
versions. To avoid having to change the Rust definitions, we implement our
own numbering system in Rust, and use an automatically-generated C shim to
convert the bitflags at runtime.

1 files changed, 64 insertions, 0 deletions

diff --git a/openssl-sys/build.rs b/openssl-sys/build.rs
index c1f12034..841c7eec 100644
--- a/openssl-sys/build.rs
+++ b/openssl-sys/build.rs
@@ -2,7 +2,10 @@ extern crate pkg_config;
 extern crate gcc;
 
 use std::env;
+use std::fmt::Write as FmtWrite;
 use std::path::PathBuf;
+use std::fs::File;
+use std::io::Write;
 
 fn main() {
     let target = env::var("TARGET").unwrap();
@@ -65,7 +68,67 @@ fn main() {
     build_openssl_shim(&include_dirs);
 }
 
+macro_rules! import_options {
+    ( $( $name:ident $val:expr  )* ) => {
+       &[ $( (stringify!($name),$val), )* ]
+    };
+}
+
+fn generate_options_shim() -> PathBuf {
+    let options: &[(&'static str,u64)]=include!("src/ssl_options.rs");
+    let mut shim = String::new();
+    writeln!(shim,"#include <stdint.h>").unwrap();
+    writeln!(shim,"#include <openssl/ssl.h>").unwrap();
+
+    for &(name,value) in options {
+        writeln!(shim,"#define RUST_{} UINT64_C({})",name,value).unwrap();
+        writeln!(shim,"#ifndef {}",name).unwrap();
+        writeln!(shim,"# define {} 0",name).unwrap();
+        writeln!(shim,"#endif").unwrap();
+    }
+
+    writeln!(shim,"#define COPY_MASK ( \\").unwrap();
+
+    let mut it=options.iter().peekable();
+    while let Some(&(name,_))=it.next()  {
+        let eol=match it.peek() {
+            Some(_) => " | \\",
+            None    => " )"
+        };
+        writeln!(shim,"    ((RUST_{0}==(uint64_t)(uint32_t){0})?RUST_{0}:UINT64_C(0)){1}",name,eol).unwrap();
+    }
+
+    writeln!(shim,"long rust_openssl_ssl_ctx_options_rust_to_c(uint64_t rustval) {{").unwrap();
+    writeln!(shim,"    long cval=rustval&COPY_MASK;").unwrap();
+    for &(name,_) in options {
+        writeln!(shim,"#if RUST_{0}!={0}",name).unwrap();
+        writeln!(shim,"    if (rustval&RUST_{0}) cval|={0};",name).unwrap();
+        writeln!(shim,"#endif").unwrap();
+    }
+    writeln!(shim,"    return cval;").unwrap();
+    writeln!(shim,"}}").unwrap();
+
+    writeln!(shim,"uint64_t rust_openssl_ssl_ctx_options_c_to_rust(long cval) {{").unwrap();
+    writeln!(shim,"    uint64_t rustval=cval&COPY_MASK;").unwrap();
+    for &(name,_) in options {
+        writeln!(shim,"#if RUST_{0}!={0}",name).unwrap();
+        writeln!(shim,"    if (cval&{0}) rustval|=RUST_{0};",name).unwrap();
+        writeln!(shim,"#endif").unwrap();
+    }
+    writeln!(shim,"    return rustval;").unwrap();
+    writeln!(shim,"}}").unwrap();
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let dest_file = PathBuf::from(&out_dir).join("ssl_ctx_options_shim.c");
+    let mut f = File::create(&dest_file).unwrap();
+
+    f.write_all(shim.as_bytes()).unwrap();
+
+    dest_file
+}
+
 fn build_openssl_shim(include_paths: &[PathBuf]) {
+    let options_shim_file = generate_options_shim();
     let mut config = gcc::Config::new();
 
     for path in include_paths {
@@ -73,6 +136,7 @@ fn build_openssl_shim(include_paths: &[PathBuf]) {
     }
 
     config.file("src/openssl_shim.c")
+        .file(options_shim_file)
         .compile("libopenssl_shim.a");
 }