ffmpeg 下http.c http协议解析很好的代码

/*

 * HTTP protocol for ffmpeg client

 * Copyright (c) 2000, 2001 Fabrice Bellard

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "libavutil/avstring.h"

#include "avformat.h"

#include <unistd.h>

#include <strings.h>

#include "internal.h"

#include "network.h"

#include "os_support.h"

#include "httpauth.h"

/* XXX: POST protocol is not completely implemented because ffmpeg uses

   only a subset of it. */

/* used for protocol handling */

#define BUFFER_SIZE 1024

#define URL_SIZE    4096

#define MAX_REDIRECTS 8

typedef struct {

    URLContext *hd;

    unsigned char buffer[BUFFER_SIZE], *buf_ptr, *buf_end;

    int line_count;

    int http_code;

    int64_t chunksize;      /**< Used if "Transfer-Encoding: chunked" otherwise -1. */

    int64_t off, filesize;

    char location[URL_SIZE];

    HTTPAuthState auth_state;

} HTTPContext;

static int http_connect(URLContext *h, const char *path, const char *hoststr,

                        const char *auth, int *new_location);

static int http_write(URLContext *h, uint8_t *buf, int size);

/* return non zero if error */

static int http_open_cnx(URLContext *h)

{

    const char *path, *proxy_path;

    char hostname[1024], hoststr[1024];

    char auth[1024];

    char path1[1024];

    char buf[1024];

    int port, use_proxy, err, location_changed = 0, redirects = 0;

    HTTPAuthType cur_auth_type;

    HTTPContext *s = h->priv_data;

    URLContext *hd = NULL;

    proxy_path = getenv("http_proxy");

    use_proxy = (proxy_path != NULL) && !getenv("no_proxy") &&

        av_strstart(proxy_path, "http://", NULL);

    /* fill the dest addr */

 redo:

    /* needed in any case to build the host string */

    ff_url_split(NULL, 0, auth, sizeof(auth), hostname, sizeof(hostname), &port,

                 path1, sizeof(path1), s->location);

    ff_url_join(hoststr, sizeof(hoststr), NULL, NULL, hostname, port, NULL);

    if (use_proxy) {

        ff_url_split(NULL, 0, auth, sizeof(auth), hostname, sizeof(hostname), &port,

                     NULL, 0, proxy_path);

        path = s->location;

    } else {

        if (path1[0] == '\0')

            path = "/";

        else

            path = path1;

    }

    if (port < 0)

        port = 80;

    ff_url_join(buf, sizeof(buf), "tcp", NULL, hostname, port, NULL);

    err = url_open(&hd, buf, URL_RDWR);

    if (err < 0)

        goto fail;

    s->hd = hd;

    cur_auth_type = s->auth_state.auth_type;

    if (http_connect(h, path, hoststr, auth, &location_changed) < 0)

        goto fail;

    if (s->http_code == 401) {

        if (cur_auth_type == HTTP_AUTH_NONE && s->auth_state.auth_type != HTTP_AUTH_NONE) {

            url_close(hd);

            goto redo;

        } else

            goto fail;

    }

    if ((s->http_code == 302 || s->http_code == 303) && location_changed == 1) {

        /* url moved, get next */

        url_close(hd);

        if (redirects++ >= MAX_REDIRECTS)

            return AVERROR(EIO);

        location_changed = 0;

        goto redo;

    }

    return 0;

 fail:

    if (hd)

        url_close(hd);

    return AVERROR(EIO);

}

static int http_open(URLContext *h, const char *uri, int flags)

{

    HTTPContext *s;

    int ret;

    h->is_streamed = 1;

    s = av_malloc(sizeof(HTTPContext));

    if (!s) {

        return AVERROR(ENOMEM);

    }

    h->priv_data = s;

    s->filesize = -1;

    s->chunksize = -1;

    s->off = 0;

    memset(&s->auth_state, 0, sizeof(s->auth_state));

    av_strlcpy(s->location, uri, URL_SIZE);

    ret = http_open_cnx(h);

    if (ret != 0)

        av_free (s);

    return ret;

}

static int http_getc(HTTPContext *s)

{

    int len;

    if (s->buf_ptr >= s->buf_end) {

        len = url_read(s->hd, s->buffer, BUFFER_SIZE);

        if (len < 0) {

            return AVERROR(EIO);

        } else if (len == 0) {

            return -1;

        } else {

            s->buf_ptr = s->buffer;

            s->buf_end = s->buffer + len;

        }

    }

    return *s->buf_ptr++;

}

static int http_get_line(HTTPContext *s, char *line, int line_size)

{

    int ch;

    char *q;

    q = line;

    for(;;) {

        ch = http_getc(s);

        if (ch < 0)

            return AVERROR(EIO);

        if (ch == '\n') {

            /* process line */

            if (q > line && q[-1] == '\r')

                q--;

            *q = '\0';

            return 0;

        } else {

            if ((q - line) < line_size - 1)

                *q++ = ch;

        }

    }

}

static int process_line(URLContext *h, char *line, int line_count,

                        int *new_location)

{

    HTTPContext *s = h->priv_data;

    char *tag, *p;

    /* end of header */

    if (line[0] == '\0')

        return 0;

    p = line;

    if (line_count == 0) {

        while (!isspace(*p) && *p != '\0')

            p++;

        while (isspace(*p))

            p++;

        s->http_code = strtol(p, NULL, 10);

        dprintf(NULL, "http_code=%d\n", s->http_code);

        /* error codes are 4xx and 5xx, but regard 401 as a success, so we

         * don't abort until all headers have been parsed. */

        if (s->http_code >= 400 && s->http_code < 600 && s->http_code != 401)

            return -1;

    } else {

        while (*p != '\0' && *p != ':')

            p++;

        if (*p != ':')

            return 1;

        *p = '\0';

        tag = line;

        p++;

        while (isspace(*p))

            p++;

        if (!strcmp(tag, "Location")) {

            strcpy(s->location, p);

            *new_location = 1;

        } else if (!strcmp (tag, "Content-Length") && s->filesize == -1) {

            s->filesize = atoll(p);

        } else if (!strcmp (tag, "Content-Range")) {

            /* "bytes $from-$to/$document_size" */

            const char *slash;

            if (!strncmp (p, "bytes ", 6)) {

                p += 6;

                s->off = atoll(p);

                if ((slash = strchr(p, '/')) && strlen(slash) > 0)

                    s->filesize = atoll(slash+1);

            }

            h->is_streamed = 0; /* we _can_ in fact seek */

        } else if (!strcmp (tag, "Transfer-Encoding") && !strncasecmp(p, "chunked", 7)) {

            s->filesize = -1;

            s->chunksize = 0;

        } else if (!strcmp (tag, "WWW-Authenticate")) {

            ff_http_auth_handle_header(&s->auth_state, tag, p);

        } else if (!strcmp (tag, "Authentication-Info")) {

            ff_http_auth_handle_header(&s->auth_state, tag, p);

        }

    }

    return 1;

}

static int http_connect(URLContext *h, const char *path, const char *hoststr,

                        const char *auth, int *new_location)

{

    HTTPContext *s = h->priv_data;

    int post, err;

    char line[1024];

    char *authstr = NULL;

    int64_t off = s->off;

    /* send http header */

    post = h->flags & URL_WRONLY;

    authstr = ff_http_auth_create_response(&s->auth_state, auth, path,

                                        post ? "POST" : "GET");

    snprintf(s->buffer, sizeof(s->buffer),

             "%s %s HTTP/1.1\r\n"

             "User-Agent: %s\r\n"

             "Accept: */*\r\n"

             "Range: bytes=%"PRId64"-\r\n"

             "Host: %s\r\n"

             "%s"

             "Connection: close\r\n"

             "%s"

             "\r\n",

             post ? "POST" : "GET",

             path,

             LIBAVFORMAT_IDENT,

             s->off,

             hoststr,

             authstr ? authstr : "",

             post ? "Transfer-Encoding: chunked\r\n" : "");

    av_freep(&authstr);

    if (http_write(h, s->buffer, strlen(s->buffer)) < 0)

        return AVERROR(EIO);

    /* init input buffer */

    s->buf_ptr = s->buffer;

    s->buf_end = s->buffer;

    s->line_count = 0;

    s->off = 0;

    s->filesize = -1;

    if (post) {

        /* always use chunked encoding for upload data */

        s->chunksize = 0;

        return 0;

    }

    /* wait for header */

    for(;;) {

        if (http_get_line(s, line, sizeof(line)) < 0)

            return AVERROR(EIO);

        dprintf(NULL, "header='%s'\n", line);

        err = process_line(h, line, s->line_count, new_location);

        if (err < 0)

            return err;

        if (err == 0)

            break;

        s->line_count++;

    }

    return (off == s->off) ? 0 : -1;

}

static int http_read(URLContext *h, uint8_t *buf, int size)

{

    HTTPContext *s = h->priv_data;

    int len;

    if (s->chunksize >= 0) {

        if (!s->chunksize) {

            char line[32];

            for(;;) {

                do {

                    if (http_get_line(s, line, sizeof(line)) < 0)

                        return AVERROR(EIO);

                } while (!*line);    /* skip CR LF from last chunk */

                s->chunksize = strtoll(line, NULL, 16);

                dprintf(NULL, "Chunked encoding data size: %"PRId64"'\n", s->chunksize);

                if (!s->chunksize)

                    return 0;

                break;

            }

        }

        size = FFMIN(size, s->chunksize);

    }

    /* read bytes from input buffer first */

    len = s->buf_end - s->buf_ptr;

    if (len > 0) {

        if (len > size)

            len = size;

        memcpy(buf, s->buf_ptr, len);

        s->buf_ptr += len;

    } else {

        len = url_read(s->hd, buf, size);

    }

    if (len > 0) {

        s->off += len;

        if (s->chunksize > 0)

            s->chunksize -= len;

    }

    return len;

}

/* used only when posting data */

static int http_write(URLContext *h, uint8_t *buf, int size)

{

    char temp[11];  /* 32-bit hex + CRLF + nul */

    int ret;

    char crlf[] = "\r\n";

    HTTPContext *s = h->priv_data;

    if (s->chunksize == -1) {

        /* headers are sent without any special encoding */

        return url_write(s->hd, buf, size);

    }

    /* silently ignore zero-size data since chunk encoding that would

     * signal EOF */

    if (size > 0) {

        /* upload data using chunked encoding */

        snprintf(temp, sizeof(temp), "%x\r\n", size);

        if ((ret = url_write(s->hd, temp, strlen(temp))) < 0 ||

            (ret = url_write(s->hd, buf, size)) < 0 ||

            (ret = url_write(s->hd, crlf, sizeof(crlf) - 1)) < 0)

            return ret;

    }

    return size;

}

static int http_close(URLContext *h)

{

    int ret = 0;

    char footer[] = "0\r\n\r\n";

    HTTPContext *s = h->priv_data;

    /* signal end of chunked encoding if used */

    if ((h->flags & URL_WRONLY) && s->chunksize != -1) {

        ret = url_write(s->hd, footer, sizeof(footer) - 1);

        ret = ret > 0 ? 0 : ret;

    }

    url_close(s->hd);

    av_free(s);

    return ret;

}

static int64_t http_seek(URLContext *h, int64_t off, int whence)

{

    HTTPContext *s = h->priv_data;

    URLContext *old_hd = s->hd;

    int64_t old_off = s->off;

    uint8_t old_buf[BUFFER_SIZE];

    int old_buf_size;

    if (whence == AVSEEK_SIZE)

        return s->filesize;

    else if ((s->filesize == -1 && whence == SEEK_END) || h->is_streamed)

        return -1;

    /* we save the old context in case the seek fails */

    old_buf_size = s->buf_end - s->buf_ptr;

    memcpy(old_buf, s->buf_ptr, old_buf_size);

    s->hd = NULL;

    if (whence == SEEK_CUR)

        off += s->off;

    else if (whence == SEEK_END)

        off += s->filesize;

    s->off = off;

    /* if it fails, continue on old connection */

    if (http_open_cnx(h) < 0) {

        memcpy(s->buffer, old_buf, old_buf_size);

        s->buf_ptr = s->buffer;

        s->buf_end = s->buffer + old_buf_size;

        s->hd = old_hd;

        s->off = old_off;

        return -1;

    }

    url_close(old_hd);

    return off;

}

static int

http_get_file_handle(URLContext *h)

{

    HTTPContext *s = h->priv_data;

    return url_get_file_handle(s->hd);

}

URLProtocol http_protocol = {

    "http",

    http_open,

    http_read,

    http_write,

    http_seek,

    http_close,

    .url_get_file_handle = http_get_file_handle,

};