b64encode and b64decode functions were taken from zstream project which was
written by Steven Barth and John Crispin.

Signed-off-by: Luka Perkov <[email protected]>
---
 file.c | 197 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 187 insertions(+), 10 deletions(-)

diff --git a/file.c b/file.c
index 9e87a10..54f5d8a 100644
--- a/file.c
+++ b/file.c
@@ -79,14 +79,27 @@ static const struct blobmsg_policy 
rpc_file_r_policy[__RPC_F_R_MAX] = {
 };
 
 enum {
+       RPC_F_RB_PATH,
+       RPC_F_RB_BASE64,
+       __RPC_F_RB_MAX,
+};
+
+static const struct blobmsg_policy rpc_file_rb_policy[__RPC_F_RB_MAX] = {
+       [RPC_F_RB_PATH]   = { .name = "path",   .type = BLOBMSG_TYPE_STRING },
+       [RPC_F_RB_BASE64] = { .name = "base64", .type = BLOBMSG_TYPE_BOOL   },
+};
+
+enum {
        RPC_F_RW_PATH,
        RPC_F_RW_DATA,
+       RPC_F_RW_BASE64,
        __RPC_F_RW_MAX,
 };
 
 static const struct blobmsg_policy rpc_file_rw_policy[__RPC_F_RW_MAX] = {
-       [RPC_F_RW_PATH] = { .name = "path", .type = BLOBMSG_TYPE_STRING },
-       [RPC_F_RW_DATA] = { .name = "data", .type = BLOBMSG_TYPE_STRING },
+       [RPC_F_RW_PATH]   = { .name = "path",   .type = BLOBMSG_TYPE_STRING },
+       [RPC_F_RW_DATA]   = { .name = "data",   .type = BLOBMSG_TYPE_STRING },
+       [RPC_F_RW_BASE64] = { .name = "base64", .type = BLOBMSG_TYPE_BOOL   },
 };
 
 enum {
@@ -114,6 +127,122 @@ static const char *d_types[] = {
 };
 
 
+static const unsigned char b64encode_tbl[] =
+       "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+static char
+*b64encode(const void *in, size_t *len)
+{
+       size_t lenout, pad, i;
+       const uint8_t *data = (const uint8_t *) in;
+
+       lenout = *len / 3;
+       lenout *= 4;
+       pad = *len % 3;
+
+       if (*len == 0) {
+               return strdup("");
+       } else if (pad) {
+               lenout += 4;
+       }
+
+       char *out = calloc(lenout + 1, sizeof(char));
+       if (!out)
+               return NULL;
+
+       uint8_t *o = (uint8_t*)out;
+       for (i = 0; i < *len; i += 3) {
+               uint32_t cv = (data[i] << 16) | (data[i+1] << 8) | data[i+2];
+               *(o+3) = b64encode_tbl[ cv        & 0x3f];
+               *(o+2) = b64encode_tbl[(cv >> 6)  & 0x3f];
+               *(o+1) = b64encode_tbl[(cv >> 12) & 0x3f];
+               *o     = b64encode_tbl[(cv >> 18) & 0x3f];
+               o += 4;
+       }
+
+       if (pad) {
+               uint32_t cv = data[*len-pad] << 16;
+               *(o-1) = '=';
+               *(o-2) = '=';
+               if (pad == 2) {
+                       cv |= data[*len-pad+1] << 8;
+                       *(o-2) = b64encode_tbl[(cv >> 6) & 0x3f];
+               }
+               *(o-3) = b64encode_tbl[(cv >> 12) & 0x3f];
+               *(o-4) = b64encode_tbl[(cv >> 18) & 0x3f];
+       }
+
+       out[lenout] = 0;
+       *len = lenout;
+       return out;
+}
+
+static const unsigned char b64decode_tbl[] = {
+       0x3e, 0xff, 0xff, 0xff, 0x3f, 0x34, 0x35, 0x36,
+       0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0xff,
+       0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0x00, 0x01,
+       0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
+       0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11,
+       0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
+       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x1a, 0x1b,
+       0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23,
+       0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
+       0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33
+};
+
+static void
+*b64decode(const char *in, size_t *len)
+{
+       size_t lenout, i;
+
+       if (*len == 0) {
+               return strdup("");
+       } else if (*len % 4) {
+               errno = EINVAL;
+               return NULL;
+       }
+
+       lenout = *len / 4 * 3;
+
+       unsigned char *out = calloc(lenout + 1, sizeof(char));
+       if (!out)
+               return NULL;
+
+       unsigned char *o = out;
+       for (i = 0; i < *len; i += 4) {
+               uint32_t cv = 0;
+               for (int j = 0; j < 4; j++) {
+                       unsigned char c = in[i + j] - 43;
+                       if (c > 79 || (c = b64decode_tbl[c]) == 0xff) {
+                               free(out);
+                               errno = EINVAL;
+                               return NULL;
+                       }
+
+                       cv |= c;
+                       if (j != 3) {
+                               cv <<= 6;
+                       }
+               }
+
+               *(o+2) = (unsigned char)(cv & 0xff);
+               *(o+1) = (unsigned char)((cv >>  8) & 0xff);
+               *o     = (unsigned char)((cv >> 16) & 0xff);
+               o += 3;
+       }
+
+       if (in[*len-1] == '=') {
+               lenout--;
+       }
+
+       if (in[*len-2] == '=') {
+               lenout--;
+       }
+
+       *len = lenout;
+       return out;
+}
+
 static int
 rpc_errno_status(void)
 {
@@ -162,12 +291,22 @@ rpc_file_read(struct ubus_context *ctx, struct 
ubus_object *obj,
               struct ubus_request_data *req, const char *method,
               struct blob_attr *msg)
 {
-       int fd, rv, len;
+       static struct blob_attr *tb[__RPC_F_RB_MAX];
+       bool base64 = false;
+       int fd, rv;
+       ssize_t len;
        char *path;
        struct stat s;
        char *wbuf;
 
-       if (!rpc_check_path(msg, &path, &s))
+       blobmsg_parse(rpc_file_rb_policy, __RPC_F_RB_MAX, tb, blob_data(msg), 
blob_len(msg));
+
+       if (!tb[RPC_F_RB_PATH])
+               return rpc_errno_status();
+
+       path = blobmsg_data(tb[RPC_F_RB_PATH]);
+
+       if (stat(path, &s))
                return rpc_errno_status();
 
        if (s.st_size >= RPC_FILE_MAX_SIZE)
@@ -182,7 +321,14 @@ rpc_file_read(struct ubus_context *ctx, struct ubus_object 
*obj,
 
        blob_buf_init(&buf, 0);
 
-       wbuf = blobmsg_alloc_string_buffer(&buf, "data", s.st_size + 1);
+       if (tb[RPC_F_RB_BASE64])
+               base64 = blobmsg_get_bool(tb[RPC_F_RB_BASE64]);
+
+       if (base64) {
+               wbuf = blobmsg_alloc_string_buffer(&buf, "data", (s.st_size / 
3) * 4 + 5);
+       } else {
+               wbuf = blobmsg_alloc_string_buffer(&buf, "data", s.st_size + 1);
+       }
 
        if (!wbuf)
        {
@@ -196,14 +342,25 @@ rpc_file_read(struct ubus_context *ctx, struct 
ubus_object *obj,
                goto out;
        }
 
+       if (base64) {
+               void *data = b64encode(wbuf, (size_t *) &len);
+               if (!data) {
+                       rv = UBUS_STATUS_UNKNOWN_ERROR;
+                       goto out;
+               }
+
+               memcpy(wbuf, data, len);
+               free(data);
+       }
+
        *(wbuf + len) = 0;
        blobmsg_add_string_buffer(&buf);
 
        ubus_send_reply(ctx, req, buf.head);
-       blob_buf_free(&buf);
        rv = UBUS_STATUS_OK;
 
 out:
+       blob_buf_free(&buf);
        close(fd);
        return rv;
 }
@@ -213,8 +370,11 @@ rpc_file_write(struct ubus_context *ctx, struct 
ubus_object *obj,
                struct ubus_request_data *req, const char *method,
                struct blob_attr *msg)
 {
-       int fd;
        struct blob_attr *tb[__RPC_F_RW_MAX];
+       bool base64 = false;
+       int fd, rv = 0;
+       void *rbuf;
+       size_t rbuf_len;
 
        blobmsg_parse(rpc_file_rw_policy, __RPC_F_RW_MAX, tb,
                      blob_data(msg), blob_len(msg));
@@ -222,10 +382,27 @@ rpc_file_write(struct ubus_context *ctx, struct 
ubus_object *obj,
        if (!tb[RPC_F_RW_PATH] || !tb[RPC_F_RW_DATA])
                return UBUS_STATUS_INVALID_ARGUMENT;
 
-       if ((fd = open(blobmsg_data(tb[RPC_F_RW_PATH]), O_CREAT | O_TRUNC | 
O_WRONLY)) < 0)
+       if ((fd = open(blobmsg_data(tb[RPC_F_RW_PATH]), O_CREAT | O_WRONLY | 
O_TRUNC)) < 0)
                return rpc_errno_status();
 
-       if (write(fd, blobmsg_data(tb[RPC_F_RW_DATA]), 
blobmsg_data_len(tb[RPC_F_RW_DATA])) < 0)
+       if (tb[RPC_F_RW_BASE64])
+               base64 = blobmsg_get_bool(tb[RPC_F_RW_BASE64]);
+
+       if (base64) {
+               rbuf_len = blobmsg_data_len(tb[RPC_F_RW_DATA]) - 1;
+               rbuf = b64decode(blobmsg_data(tb[RPC_F_RW_DATA]), &rbuf_len);
+       } else {
+               rbuf_len = blobmsg_data_len(tb[RPC_F_RW_DATA]);
+               rbuf = blobmsg_data(tb[RPC_F_RW_DATA]);
+       }
+
+       if (write(fd, rbuf, rbuf_len) < 0)
+               rv = -1;
+
+       if (base64)
+               free(rbuf);
+               
+       if (rv)
                return rpc_errno_status();
 
        if (fsync(fd) < 0)
@@ -643,7 +820,7 @@ static int
 rpc_file_api_init(const struct rpc_daemon_ops *o, struct ubus_context *ctx)
 {
        static const struct ubus_method file_methods[] = {
-               UBUS_METHOD("read",    rpc_file_read,  rpc_file_r_policy),
+               UBUS_METHOD("read",    rpc_file_read,  rpc_file_rb_policy),
                UBUS_METHOD("write",   rpc_file_write, rpc_file_rw_policy),
                UBUS_METHOD("list",    rpc_file_list,  rpc_file_r_policy),
                UBUS_METHOD("stat",    rpc_file_stat,  rpc_file_r_policy),
-- 
2.3.3
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