Improve the base64 utility functions.

The low-level functions to handle a single atom of base64 at a time
have been in 'utils' / misc.h for ages, but the higher-level family of
base64_encode functions that handle a whole data block were hidden
away in sshpubk.c, and there was no higher-level decode function at
all.

Now moved both into 'utils' modules and declared them in misc.h rather
than ssh.h. Also, improved the APIs: they all take ptrlen in place of
separate data and length arguments, their naming is more consistent
and more explicit (the previous base64_encode which didn't name its
destination is now base64_encode_fp), and the encode functions now
accept cpl == 0 as a special case meaning that the output base64 data
is wanted in the form of an unbroken single-line string with no
trailing \n.

import.c

@@ -1075,7 +1075,7 @@ static bool openssh_pem_write(
             fprintf(fp, "%02X", iv[i]);
         fprintf(fp, "\n\n");
     }
-    base64_encode(fp, outblob->u, outblob->len, 64);
+    base64_encode_fp(fp, ptrlen_from_strbuf(outblob), 64);
     fputs(footer, fp);
     fclose(fp);
     ret = true;
@@ -1606,7 +1606,7 @@ static bool openssh_new_write(
     if (!fp)
         goto error;
     fputs("-----BEGIN OPENSSH PRIVATE KEY-----\n", fp);
-    base64_encode(fp, cblob->u, cblob->len, 64);
+    base64_encode_fp(fp, ptrlen_from_strbuf(cblob), 64);
     fputs("-----END OPENSSH PRIVATE KEY-----\n", fp);
     fclose(fp);
     ret = true;
@@ -2308,7 +2308,7 @@ static bool sshcom_write(
         }
         fprintf(fp, "%s\"\n", c);
     }
-    base64_encode(fp, outblob->u, outblob->len, 70);
+    base64_encode_fp(fp, ptrlen_from_strbuf(outblob), 70);
     fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
     fclose(fp);
     ret = true;

misc.h

@@ -108,6 +108,12 @@ bool strendswith(const char *s, const char *t);
 
 void base64_encode_atom(const unsigned char *data, int n, char *out);
 int base64_decode_atom(const char *atom, unsigned char *out);
+void base64_decode_bs(BinarySink *bs, ptrlen data);
+void base64_decode_fp(FILE *fp, ptrlen data);
+strbuf *base64_decode_sb(ptrlen data);
+void base64_encode_bs(BinarySink *bs, ptrlen data, int cpl);
+void base64_encode_fp(FILE *fp, ptrlen data, int cpl);
+strbuf *base64_encode_sb(ptrlen data, int cpl);
 
 struct bufchain_granule;
 struct bufchain_tag {

ssh.h

@@ -1290,11 +1290,7 @@ static inline bool is_base64_char(char c)
             c == '+' || c == '/' || c == '=');
 }
 
-extern int base64_decode_atom(const char *atom, unsigned char *out);
 extern int base64_lines(int datalen);
-extern void base64_encode_atom(const unsigned char *data, int n, char *out);
-extern void base64_encode(FILE *fp, const unsigned char *data, int datalen,
-                          int cpl);
 
 /* ppk_load_* can return this as an error */
 extern ssh2_userkey ssh2_wrong_passphrase;

sshpubk.c

@@ -1391,37 +1391,6 @@ int base64_lines(int datalen)
     return (datalen + 47) / 48;
 }
 
-static void base64_encode_s(BinarySink *bs, const unsigned char *data,
-                            int datalen, int cpl)
-{
-    int linelen = 0;
-    char out[4];
-    int n, i;
-
-    while (datalen > 0) {
-        n = (datalen < 3 ? datalen : 3);
-        base64_encode_atom(data, n, out);
-        data += n;
-        datalen -= n;
-        for (i = 0; i < 4; i++) {
-            if (linelen >= cpl) {
-                linelen = 0;
-                put_byte(bs, '\n');
-            }
-            put_byte(bs, out[i]);
-            linelen++;
-        }
-    }
-    put_byte(bs, '\n');
-}
-
-void base64_encode(FILE *fp, const unsigned char *data, int datalen, int cpl)
-{
-    stdio_sink ss;
-    stdio_sink_init(&ss, fp);
-    base64_encode_s(BinarySink_UPCAST(&ss), data, datalen, cpl);
-}
-
 const ppk_save_parameters ppk_save_default_parameters = {
     .fmt_version = 3,
 
@@ -1566,7 +1535,7 @@ strbuf *ppk_save_sb(ssh2_userkey *key, const char *passphrase,
     put_fmt(out, "Encryption: %s\n", cipherstr);
     put_fmt(out, "Comment: %s\n", key->comment);
     put_fmt(out, "Public-Lines: %d\n", base64_lines(pub_blob->len));
-    base64_encode_s(BinarySink_UPCAST(out), pub_blob->u, pub_blob->len, 64);
+    base64_encode_bs(BinarySink_UPCAST(out), ptrlen_from_strbuf(pub_blob), 64);
     if (params.fmt_version == 3 && ciphertype->keylen != 0) {
         put_fmt(out, "Key-Derivation: %s\n",
                 params.argon2_flavour == Argon2d ? "Argon2d" :
@@ -1582,8 +1551,8 @@ strbuf *ppk_save_sb(ssh2_userkey *key, const char *passphrase,
         put_fmt(out, "\n");
     }
     put_fmt(out, "Private-Lines: %d\n", base64_lines(priv_encrypted_len));
-    base64_encode_s(BinarySink_UPCAST(out),
-                    priv_blob_encrypted, priv_encrypted_len, 64);
+    base64_encode_bs(BinarySink_UPCAST(out),
+                     make_ptrlen(priv_blob_encrypted, priv_encrypted_len), 64);
     put_fmt(out, "Private-MAC: ");
     for (i = 0; i < macalg->len; i++)
         put_fmt(out, "%02x", priv_mac[i]);

utils/CMakeLists.txt

@@ -2,7 +2,9 @@ add_sources_from_current_dir(utils
   antispoof.c
   backend_socket_log.c
   base64_decode_atom.c
+  base64_decode.c
   base64_encode_atom.c
+  base64_encode.c
   bufchain.c
   buildinfo.c
   burnstr.c

utils/base64_decode.c

@@ -0,0 +1,37 @@
+#include "misc.h"
+
+void base64_decode_bs(BinarySink *bs, ptrlen input)
+{
+    BinarySource src[1];
+    BinarySource_BARE_INIT_PL(src, input);
+
+    while (get_avail(src)) {
+        char b64atom[4];
+        unsigned char binatom[3];
+
+        for (size_t i = 0; i < 4 ;) {
+            char c = get_byte(src);
+            if (get_err(src))
+                c = '=';
+            if (c == '\n' || c == '\r')
+                continue;
+            b64atom[i++] = c;
+        }
+
+        put_data(bs, binatom, base64_decode_atom(b64atom, binatom));
+    }
+}
+
+void base64_decode_fp(FILE *fp, ptrlen input)
+{
+    stdio_sink ss;
+    stdio_sink_init(&ss, fp);
+    base64_decode_bs(BinarySink_UPCAST(&ss), input);
+}
+
+strbuf *base64_decode_sb(ptrlen input)
+{
+    strbuf *sb = strbuf_new_nm();
+    base64_decode_bs(BinarySink_UPCAST(sb), input);
+    return sb;
+}

utils/base64_encode.c

@@ -0,0 +1,40 @@
+#include "misc.h"
+
+void base64_encode_bs(BinarySink *bs, ptrlen input, int cpl)
+{
+    BinarySource src[1];
+    BinarySource_BARE_INIT_PL(src, input);
+    int linelen = 0;
+
+    while (get_avail(src)) {
+        size_t n = get_avail(src) < 3 ? get_avail(src) : 3;
+        ptrlen binatom = get_data(src, n);
+
+        char b64atom[4];
+        base64_encode_atom(binatom.ptr, binatom.len, b64atom);
+        for (size_t i = 0; i < 4; i++) {
+            if (cpl > 0 && linelen >= cpl) {
+                linelen = 0;
+                put_byte(bs, '\n');
+            }
+            put_byte(bs, b64atom[i]);
+            linelen++;
+        }
+    }
+    if (cpl > 0)
+        put_byte(bs, '\n');
+}
+
+void base64_encode_fp(FILE *fp, ptrlen input, int cpl)
+{
+    stdio_sink ss;
+    stdio_sink_init(&ss, fp);
+    base64_encode_bs(BinarySink_UPCAST(&ss), input, cpl);
+}
+
+strbuf *base64_encode_sb(ptrlen input, int cpl)
+{
+    strbuf *sb = strbuf_new_nm();
+    base64_encode_bs(BinarySink_UPCAST(sb), input, cpl);
+    return sb;
+}