[FFmpeg-devel] [PATCH 06/12] avformat/http: use AVBPrint to construct HTTP request

[Andreas Rheinhardt]

Marton Balint:
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
>  libavformat/http.c | 79 ++++++++++++++++++++----------------------------------
>  1 file changed, 29 insertions(+), 50 deletions(-)
> 
> diff --git a/libavformat/http.c b/libavformat/http.c
> index d0df1b6d58..5fd36baab8 100644
> --- a/libavformat/http.c
> +++ b/libavformat/http.c
> @@ -27,6 +27,7 @@
>  
>  #include "libavutil/avassert.h"
>  #include "libavutil/avstring.h"
> +#include "libavutil/bprint.h"
>  #include "libavutil/opt.h"
>  #include "libavutil/time.h"
>  #include "libavutil/parseutils.h"
> @@ -1184,13 +1185,13 @@ static int http_connect(URLContext *h, const char *path, const char *local_path,
>  {
>      HTTPContext *s = h->priv_data;
>      int post, err;
> -    char headers[HTTP_HEADERS_SIZE] = "";
> +    AVBPrint request;
>      char *authstr = NULL, *proxyauthstr = NULL;
>      uint64_t off = s->off;
> -    int len = 0;
>      const char *method;
>      int send_expect_100 = 0;
> -    int ret;
> +
> +    av_bprint_init(&request, 0, BUFFER_SIZE);
>  
>      /* send http header */
>      post = h->flags & AVIO_FLAG_WRITE;
> @@ -1233,95 +1234,72 @@ static int http_connect(URLContext *h, const char *path, const char *local_path,
>          s->user_agent = av_strdup(s->user_agent_deprecated);
>      }
>  #endif
> +
> +    av_bprintf(&request, "%s %s HTTP/1.1\r\n", method, path);
> +    av_bprintf(&request, "%s", post && s->chunked_post ? "Transfer-Encoding: chunked\r\n" : "");

Looks like it wouldn't do anything if !(post && s->chunked_post), so
why not call av_bprintf() only if (post && s->chunked_post)? And then
you can use the string directly without resorting to "%s".

> +
>      /* set default headers if needed */
>      if (!has_header(s->headers, "\r\nUser-Agent: "))
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "User-Agent: %s\r\n", s->user_agent);
> +        av_bprintf(&request, "User-Agent: %s\r\n", s->user_agent);
>      if (s->referer) {
>          /* set default headers if needed */
>          if (!has_header(s->headers, "\r\nReferer: "))
> -            len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                               "Referer: %s\r\n", s->referer);
> +            av_bprintf(&request, "Referer: %s\r\n", s->referer);
>      }
>      if (!has_header(s->headers, "\r\nAccept: "))
> -        len += av_strlcpy(headers + len, "Accept: */*\r\n",
> -                          sizeof(headers) - len);
> +        av_bprintf(&request, "Accept: */*\r\n");
>      // Note: we send this on purpose even when s->off is 0 when we're probing,
>      // since it allows us to detect more reliably if a (non-conforming)
>      // server supports seeking by analysing the reply headers.
>      if (!has_header(s->headers, "\r\nRange: ") && !post && (s->off > 0 || s->end_off || s->seekable == -1)) {
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "Range: bytes=%"PRIu64"-", s->off);
> +        av_bprintf(&request, "Range: bytes=%"PRIu64"-", s->off);
>          if (s->end_off)
> -            len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                               "%"PRId64, s->end_off - 1);
> -        len += av_strlcpy(headers + len, "\r\n",
> -                          sizeof(headers) - len);
> +            av_bprintf(&request, "%"PRId64, s->end_off - 1);
> +        av_bprintf(&request, "\r\n");
>      }
>      if (send_expect_100 && !has_header(s->headers, "\r\nExpect: "))
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "Expect: 100-continue\r\n");
> +        av_bprintf(&request, "Expect: 100-continue\r\n");
>  
>      if (!has_header(s->headers, "\r\nConnection: ")) {
>          if (s->multiple_requests)
> -            len += av_strlcpy(headers + len, "Connection: keep-alive\r\n",
> -                              sizeof(headers) - len);
> +            av_bprintf(&request, "Connection: keep-alive\r\n");
>          else
> -            len += av_strlcpy(headers + len, "Connection: close\r\n",
> -                              sizeof(headers) - len);
> +            av_bprintf(&request, "Connection: close\r\n");
>      }
>  
>      if (!has_header(s->headers, "\r\nHost: "))
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "Host: %s\r\n", hoststr);
> +        av_bprintf(&request, "Host: %s\r\n", hoststr);
>      if (!has_header(s->headers, "\r\nContent-Length: ") && s->post_data)
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "Content-Length: %d\r\n", s->post_datalen);
> +        av_bprintf(&request, "Content-Length: %d\r\n", s->post_datalen);
>  
>      if (!has_header(s->headers, "\r\nContent-Type: ") && s->content_type)
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "Content-Type: %s\r\n", s->content_type);
> +        av_bprintf(&request, "Content-Type: %s\r\n", s->content_type);
>      if (!has_header(s->headers, "\r\nCookie: ") && s->cookies) {
>          char *cookies = NULL;
>          if (!get_cookies(s, &cookies, path, hoststr) && cookies) {
> -            len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                               "Cookie: %s\r\n", cookies);
> +            av_bprintf(&request, "Cookie: %s\r\n", cookies);
>              av_free(cookies);
>          }
>      }
>      if (!has_header(s->headers, "\r\nIcy-MetaData: ") && s->icy)
> -        len += av_strlcatf(headers + len, sizeof(headers) - len,
> -                           "Icy-MetaData: %d\r\n", 1);
> +        av_bprintf(&request, "Icy-MetaData: %d\r\n", 1);

This number could be part of the string.

>  
>      /* now add in custom headers */
>      if (s->headers)
> -        av_strlcpy(headers + len, s->headers, sizeof(headers) - len);
> +        av_bprintf(&request, "%s", s->headers);
>  
> -    ret = snprintf(s->buffer, sizeof(s->buffer),
> -             "%s %s HTTP/1.1\r\n"
> -             "%s"
> -             "%s"
> -             "%s"
> -             "%s%s"
> -             "\r\n",
> -             method,
> -             path,
> -             post && s->chunked_post ? "Transfer-Encoding: chunked\r\n" : "",
> -             headers,
> -             authstr ? authstr : "",
> -             proxyauthstr ? "Proxy-" : "", proxyauthstr ? proxyauthstr : "");
> +    av_bprintf(&request, "%s", authstr ? authstr : "");

Same as above for post && s->chunked_post.

> +    av_bprintf(&request, "%s%s\r\n", proxyauthstr ? "Proxy-" : "", proxyauthstr ? proxyauthstr : "");
>  
> -    av_log(h, AV_LOG_DEBUG, "request: %s\n", s->buffer);
> +    av_log(h, AV_LOG_DEBUG, "request: %s\n", request.str);
>  
> -    if (strlen(headers) + 1 == sizeof(headers) ||
> -        ret >= sizeof(s->buffer)) {
> +    if (!av_bprint_is_complete(&request)) {

Using an AVBPrint would add another possible source of error:
Allocation failure. You can check for this by checking whether request
is incomplete and request.len < BUFFER_SIZE.
(One could get rid of this by keeping a buffer of size
HTTP_HEADERS_SIZE on the stack and using av_bprint_init_for_buffer()
with this buffer; in this case, one has to remove
av_bprint_finalize(), as it would try to free the buffer, despite not
being allocated.)

>          av_log(h, AV_LOG_ERROR, "overlong headers\n");
>          err = AVERROR(EINVAL);
>          goto done;
>      }
>  
> -
> -    if ((err = ffurl_write(s->hd, s->buffer, strlen(s->buffer))) < 0)
> +    if ((err = ffurl_write(s->hd, request.str, request.len)) < 0)
>          goto done;
>  
>      if (s->post_data)
> @@ -1362,6 +1340,7 @@ static int http_connect(URLContext *h, const char *path, const char *local_path,
>  done:
>      av_freep(&authstr);
>      av_freep(&proxyauthstr);
> +    av_bprint_finalize(&request, NULL);
>      return err;
>  }
>  
>