Re: [FFmpeg-devel] [PATCH] avformat/httpauth.c Support RFC7616 [Style fixed]

[Stefano Sabatini <stefasab@gmail.com>]

On date Monday 2024-04-15 02:32:14 +0000, ������ | Eugene wrote:
> Update digest authentication in httpauth.c
> 
> - Refactor make_digest_auth() to support RFC 2617 and RFC 7617
> - Add support for SHA-256 and SHA-512/256 algorithms along with MD5
> - MD5 and SHA-256 tested, but SHA-512/256 untested due to lack of server
> - Replace AVMD5 structure with AVHashContext for hash algorithm flexibility
> - Rename update_md5_strings() to update_hash_strings() for consistency
> - Address coding style feedback from reviewer:
> 
> This is a feature update focused on digest authentication enhancements.
> Some lint issues in the existing code remain unaddressed in this patch.
> 
> Signed-off-by: Eugene-bitsensing <eugene@bitsensing.com>
> ---

>  libavformat/httpauth.c | 102 +++++++++++++++++++++--------------------
>  1 file changed, 53 insertions(+), 49 deletions(-)

add entry to Changelog?

> 
> diff --git a/libavformat/httpauth.c b/libavformat/httpauth.c
> index 9780928357..2592140526 100644
> --- a/libavformat/httpauth.c
> +++ b/libavformat/httpauth.c
> @@ -24,7 +24,7 @@
>  #include "libavutil/avstring.h"
>  #include "internal.h"
>  #include "libavutil/random_seed.h"
> -#include "libavutil/md5.h"
> +#include "libavutil/hash.h"
>  #include "urldecode.h"
>  
>  static void handle_basic_params(HTTPAuthState *state, const char *key,
> @@ -117,35 +117,35 @@ void ff_http_auth_handle_header(HTTPAuthState *state, const char *key,
>      }
>  }
>  
> -
> -static void update_md5_strings(struct AVMD5 *md5ctx, ...)
> +/* Generate hash string, updated to use AVHashContext to support other algorithms */
> +static void update_hash_strings(struct AVHashContext *hash_ctx, ...)
>  {
>      va_list vl;
>  
> -    va_start(vl, md5ctx);
> +    va_start(vl, hash_ctx);
>      while (1) {
> -        const char* str = va_arg(vl, const char*);
> +        const char *str = va_arg(vl, const char*);
>          if (!str)
>              break;
> -        av_md5_update(md5ctx, str, strlen(str));
> +        av_hash_update(hash_ctx, (const uint8_t *)str, strlen(str));
>      }
>      va_end(vl);
>  }
>  
> -/* Generate a digest reply, according to RFC 2617. */
> +/* Generate a digest reply, according to RFC 2617. Update to support RFC 7617*/
>  static char *make_digest_auth(HTTPAuthState *state, const char *username,
>                                const char *password, const char *uri,
>                                const char *method)
>  {
>      DigestParams *digest = &state->digest_params;
> -    int len;
> +    size_t len;
>      uint32_t cnonce_buf[2];
>      char cnonce[17];
>      char nc[9];
>      int i;
> -    char A1hash[33], A2hash[33], response[33];
> -    struct AVMD5 *md5ctx;
> -    uint8_t hash[16];
> +    char a1_hash[65], a2_hash[65], response[65];
> +    struct AVHashContext *hash_ctx = NULL; // use AVHashContext for other algorithm support
> +    size_t len_hash = 33; // Modifiable hash length, MD5:32, SHA-2:64
>      char *authstr;
>  
>      digest->nc++;
> @@ -156,52 +156,56 @@ static char *make_digest_auth(HTTPAuthState *state, const char *username,
>          cnonce_buf[i] = av_get_random_seed();
>      ff_data_to_hex(cnonce, (const uint8_t*) cnonce_buf, sizeof(cnonce_buf), 1);
>  
> -    md5ctx = av_md5_alloc();
> -    if (!md5ctx)
> -        return NULL;
> -
> -    av_md5_init(md5ctx);
> -    update_md5_strings(md5ctx, username, ":", state->realm, ":", password, NULL);
> -    av_md5_final(md5ctx, hash);
> -    ff_data_to_hex(A1hash, hash, 16, 1);
> -
> -    if (!strcmp(digest->algorithm, "") || !strcmp(digest->algorithm, "MD5")) {
> -    } else if (!strcmp(digest->algorithm, "MD5-sess")) {
> -        av_md5_init(md5ctx);
> -        update_md5_strings(md5ctx, A1hash, ":", digest->nonce, ":", cnonce, NULL);
> -        av_md5_final(md5ctx, hash);
> -        ff_data_to_hex(A1hash, hash, 16, 1);
> -    } else {
> -        /* Unsupported algorithm */
> -        av_free(md5ctx);
> +    /* Generate hash context by algorithm. */
> +    const char *algorithm = digest->algorithm;

> +    const char *hashing_algorithm;

nit++: to avoid semantic overlap I'd rather name this
selected_algorithm

> +    if (!*algorithm) {
> +        algorithm = "MD5";  // if empty, use MD5 as Default 
> +        hashing_algorithm = "MD5";
> +    } else if (av_stristr(algorithm, "MD5")) {
> +        hashing_algorithm = "MD5";
> +    } else if (av_stristr(algorithm, "sha256") || av_stristr(algorithm, "sha-256")) {
> +        hashing_algorithm = "SHA256";
> +        len_hash = 65; // SHA-2: 64 characters.
> +    } else if (av_stristr(algorithm, "sha512-256") || av_stristr(algorithm, "sha-512-256")) {
> +        hashing_algorithm = "SHA512_256";
> +        len_hash = 65; // SHA-2: 64 characters.
> +    } else { // Unsupported algorithm
>          return NULL;
>      }
>  
> -    av_md5_init(md5ctx);
> -    update_md5_strings(md5ctx, method, ":", uri, NULL);
> -    av_md5_final(md5ctx, hash);
> -    ff_data_to_hex(A2hash, hash, 16, 1);
> +    int ret = av_hash_alloc(&hash_ctx, hashing_algorithm);
> +    if (ret < 0)
> +        return NULL;
>  
> -    av_md5_init(md5ctx);
> -    update_md5_strings(md5ctx, A1hash, ":", digest->nonce, NULL);
> -    if (!strcmp(digest->qop, "auth") || !strcmp(digest->qop, "auth-int")) {
> -        update_md5_strings(md5ctx, ":", nc, ":", cnonce, ":", digest->qop, NULL);
> +    /* a1 hash calculation */
> +    av_hash_init(hash_ctx);
> +    update_hash_strings(hash_ctx, username, ":", state->realm, ":", password, NULL);
> +    if (av_stristr(algorithm, "-sess")) {
> +        update_hash_strings(hash_ctx, ":", digest->nonce, ":", cnonce, NULL);
>      }
> -    update_md5_strings(md5ctx, ":", A2hash, NULL);
> -    av_md5_final(md5ctx, hash);
> -    ff_data_to_hex(response, hash, 16, 1);
> -
> -    av_free(md5ctx);
> -
> -    if (!strcmp(digest->qop, "") || !strcmp(digest->qop, "auth")) {
> -    } else if (!strcmp(digest->qop, "auth-int")) {
> -        /* qop=auth-int not supported */
> -        return NULL;
> -    } else {
> -        /* Unsupported qop value. */
> +    av_hash_final_hex(hash_ctx, a1_hash, len_hash);
> +
> +    /* a2 hash calculation */
> +    av_hash_init(hash_ctx);
> +    update_hash_strings(hash_ctx, method, ":", uri, NULL);
> +    av_hash_final_hex(hash_ctx, a2_hash, len_hash);
> +    
> +    /* response hash calculation */
> +    av_hash_init(hash_ctx);
> +    update_hash_strings(hash_ctx, a1_hash, ":", digest->nonce, NULL);
> +    if (!strcmp(digest->qop, "auth")) {
> +        update_hash_strings(hash_ctx, ":", nc, ":", cnonce, ":", digest->qop, NULL);
> +    } else if (!strcmp(digest->qop, "auth-int")) { // unsupported
> +        av_hash_freep(&hash_ctx);
>          return NULL;
>      }
> +    update_hash_strings(hash_ctx, ":", a2_hash, NULL);
> +    update_hash_strings(hash_ctx, NULL);
> +    av_hash_final_hex(hash_ctx, response, len_hash);
> +    av_hash_freep(&hash_ctx);
>  
> +    /* Authorization header generation */
>      len = strlen(username) + strlen(state->realm) + strlen(digest->nonce) +
>                strlen(uri) + strlen(response) + strlen(digest->algorithm) +
>                strlen(digest->opaque) + strlen(digest->qop) + strlen(cnonce) +
> -- 
> 2.42.0.windows.2

Looks good to me otherwise, I'll wait a few more days to let more
comments before applying this, thanks.
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