Re: [PATCH] block/curl: rewrite http header parsing function

[Vladimir Sementsov-Ogievskiy]

On 29.06.24 17:25, Michael Tokarev wrote:
> Existing code was long, unclear and twisty.
>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

> ---
>   block/curl.c | 44 ++++++++++++++++++--------------------------
>   1 file changed, 18 insertions(+), 26 deletions(-)
>
> diff --git a/block/curl.c b/block/curl.c
> index 419f7c89ef..9802d0319d 100644
> --- a/block/curl.c
> +++ b/block/curl.c
> @@ -210,37 +210,29 @@ static size_t curl_header_cb(void *ptr, size_t size, 
> size_t nmemb, void *opaque)
>   {
>       BDRVCURLState *s = opaque;
>       size_t realsize = size * nmemb;
> -    const char *header = (char *)ptr;
> -    const char *end = header + realsize;
> -    const char *accept_ranges = "accept-ranges:";
> -    const char *bytes = "bytes";
> +    const char *p = ptr;
> +    const char *end = p + realsize;
> +    const char *t = "accept-ranges : bytes "; /* A lowercase template */

Note: you make parser less strict: you allow "bytes" to be uppercase (was allowed 
only for accept-ranges", and you allow whitespaces before colon.

>   
> -    if (realsize >= strlen(accept_ranges)
> -        && g_ascii_strncasecmp(header, accept_ranges,
> -                               strlen(accept_ranges)) == 0) {
> -
> -        char *p = strchr(header, ':') + 1;
> -
> -        /* Skip whitespace between the header name and value. */
> -        while (p < end && *p && g_ascii_isspace(*p)) {
> -            p++;
> -        }
> -
> -        if (end - p >= strlen(bytes)
> -            && strncmp(p, bytes, strlen(bytes)) == 0) {
> -
> -            /* Check that there is nothing but whitespace after the value. */
> -            p += strlen(bytes);
> -            while (p < end && *p && g_ascii_isspace(*p)) {
> -                p++;
> -            }
> -
> -            if (p == end || !*p) {
> -                s->accept_range = true;
> +    /* check if header matches the "t" template */
> +    for (;;) {
> +        if (*t == ' ') { /* space in t matches any amount of isspace in p */
> +            if (p < end && g_ascii_isspace(*p)) {
> +                ++p;
> +            } else {
> +                ++t;
>               }
> +        } else if (*t && p < end && *t == g_ascii_tolower(*p)) {
> +            ++p, ++t;
> +        } else {
> +            break;
>           }
>       }
>   
> +    if (!*t && p == end) { /* if we managed to reach ends of both strings */
> +        s->accept_range = true;
> +    }
> +
>       return realsize;
>   }
>   

--
Best regards,
Vladimir