Add HTTP protocol using curl v6

Currently Qemu can read from posix I/O and NBD. This patch adds a
third protocol to the game: HTTP.

In certain situations it can be useful to access HTTP data directly,
for example if you want to try out an http provided OS image, but
don't know if you want to download it yet.

Using this patch you can now try it on on the fly. Just use it like:

qemu -cdrom http://host/path/my.iso

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 523 insertions, 0 deletions

diff --git a/block/curl.c b/block/curl.c
new file mode 100644
index 0000000..5d1487d
--- /dev/null
+++ b/block/curl.c
@@ -0,0 +1,523 @@
+/*
+ * QEMU Block driver for CURL images
+ *
+ * Copyright (c) 2009 Alexander Graf <agraf@suse.de>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#include "qemu-common.h"
+#include "block_int.h"
+#include <curl/curl.h>
+
+// #define DEBUG
+// #define DEBUG_VERBOSE
+
+#ifdef DEBUG_CURL
+#define dprintf(fmt, ...) do { printf(fmt, ## __VA_ARGS__); } while (0)
+#else
+#define dprintf(fmt, ...) do { } while (0)
+#endif
+
+#define CURL_NUM_STATES 8
+#define CURL_NUM_ACB    8
+#define SECTOR_SIZE     512
+#define READ_AHEAD_SIZE (256 * 1024)
+
+#define FIND_RET_NONE   0
+#define FIND_RET_OK     1
+#define FIND_RET_WAIT   2
+
+struct BDRVCURLState;
+
+typedef struct CURLAIOCB {
+    BlockDriverAIOCB common;
+    QEMUIOVector *qiov;
+    size_t start;
+    size_t end;
+} CURLAIOCB;
+
+typedef struct CURLState
+{
+    struct BDRVCURLState *s;
+    CURLAIOCB *acb[CURL_NUM_ACB];
+    CURL *curl;
+    char *orig_buf;
+    size_t buf_start;
+    size_t buf_off;
+    size_t buf_len;
+    char range[128];
+    char errmsg[CURL_ERROR_SIZE];
+    char in_use;
+} CURLState;
+
+typedef struct BDRVCURLState {
+    CURLM *multi;
+    size_t len;
+    CURLState states[CURL_NUM_STATES];
+    char *url;
+} BDRVCURLState;
+
+static void curl_clean_state(CURLState *s);
+static void curl_multi_do(void *arg);
+
+static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
+                        void *s, void *sp)
+{
+    dprintf("CURL (AIO): Sock action %d on fd %d\n", action, fd);
+    switch (action) {
+        case CURL_POLL_IN:
+            qemu_aio_set_fd_handler(fd, curl_multi_do, NULL, NULL, s);
+            break;
+        case CURL_POLL_OUT:
+            qemu_aio_set_fd_handler(fd, NULL, curl_multi_do, NULL, s);
+            break;
+        case CURL_POLL_INOUT:
+            qemu_aio_set_fd_handler(fd, curl_multi_do,
+                                    curl_multi_do, NULL, s);
+            break;
+        case CURL_POLL_REMOVE:
+            qemu_aio_set_fd_handler(fd, NULL, NULL, NULL, NULL);
+            break;
+    }
+
+    return 0;
+}
+
+static size_t curl_size_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
+{
+    CURLState *s = ((CURLState*)opaque);
+    size_t realsize = size * nmemb;
+    long long fsize;
+
+    if(sscanf(ptr, "Content-Length: %lld", &fsize) == 1)
+        s->s->len = fsize;
+
+    return realsize;
+}
+
+static size_t curl_read_cb(void *ptr, size_t size, size_t nmemb, void *opaque)
+{
+    CURLState *s = ((CURLState*)opaque);
+    size_t realsize = size * nmemb;
+    int i;
+
+    dprintf("CURL: Just reading %lld bytes\n", (unsigned long long)realsize);
+
+    if (!s || !s->orig_buf)
+        goto read_end;
+
+    memcpy(s->orig_buf + s->buf_off, ptr, realsize);
+    s->buf_off += realsize;
+
+    for(i=0; i<CURL_NUM_ACB; i++) {
+        CURLAIOCB *acb = s->acb[i];
+
+        if (!acb)
+            continue;
+
+        if ((s->buf_off >= acb->end)) {
+            qemu_iovec_from_buffer(acb->qiov, s->orig_buf + acb->start,
+                                   acb->end - acb->start);
+            acb->common.cb(acb->common.opaque, 0);
+            qemu_aio_release(acb);
+            s->acb[i] = NULL;
+        }
+    }
+
+read_end:
+    return realsize;
+}
+
+static int curl_find_buf(BDRVCURLState *s, size_t start, size_t len,
+                         CURLAIOCB *acb)
+{
+    int i;
+    size_t end = start + len;
+
+    for (i=0; i<CURL_NUM_STATES; i++) {
+        CURLState *state = &s->states[i];
+        size_t buf_end = (state->buf_start + state->buf_off);
+        size_t buf_fend = (state->buf_start + state->buf_len);
+
+        if (!state->orig_buf)
+            continue;
+        if (!state->buf_off)
+            continue;
+
+        // Does the existing buffer cover our section?
+        if ((start >= state->buf_start) &&
+            (start <= buf_end) &&
+            (end >= state->buf_start) &&
+            (end <= buf_end))
+        {
+            char *buf = state->orig_buf + (start - state->buf_start);
+
+            qemu_iovec_from_buffer(acb->qiov, buf, len);
+            acb->common.cb(acb->common.opaque, 0);
+
+            return FIND_RET_OK;
+        }
+
+        // Wait for unfinished chunks
+        if ((start >= state->buf_start) &&
+            (start <= buf_fend) &&
+            (end >= state->buf_start) &&
+            (end <= buf_fend))
+        {
+            int j;
+
+            acb->start = start - state->buf_start;
+            acb->end = acb->start + len;
+
+            for (j=0; j<CURL_NUM_ACB; j++) {
+                if (!state->acb[j]) {
+                    state->acb[j] = acb;
+                    return FIND_RET_WAIT;
+                }
+            }
+        }
+    }
+
+    return FIND_RET_NONE;
+}
+
+static void curl_multi_do(void *arg)
+{
+    BDRVCURLState *s = (BDRVCURLState *)arg;
+    int running;
+    int r;
+    int msgs_in_queue;
+
+    if (!s->multi)
+        return;
+
+    do {
+        r = curl_multi_socket_all(s->multi, &running);
+    } while(r == CURLM_CALL_MULTI_PERFORM);
+
+    /* Try to find done transfers, so we can free the easy
+     * handle again. */
+    do {
+        CURLMsg *msg;
+        msg = curl_multi_info_read(s->multi, &msgs_in_queue);
+
+        if (!msg)
+            break;
+        if (msg->msg == CURLMSG_NONE)
+            break;
+
+        switch (msg->msg) {
+            case CURLMSG_DONE:
+            {
+                CURLState *state = NULL;
+                curl_easy_getinfo(msg->easy_handle, CURLINFO_PRIVATE, (char**)&state);
+                curl_clean_state(state);
+                break;
+            }
+            default:
+                msgs_in_queue = 0;
+                break;
+        }
+    } while(msgs_in_queue);
+}
+
+static CURLState *curl_init_state(BDRVCURLState *s)
+{
+    CURLState *state = NULL;
+    int i, j;
+
+    do {
+        for (i=0; i<CURL_NUM_STATES; i++) {
+            for (j=0; j<CURL_NUM_ACB; j++)
+                if (s->states[i].acb[j])
+                    continue;
+            if (s->states[i].in_use)
+                continue;
+
+            state = &s->states[i];
+            state->in_use = 1;
+            break;
+        }
+        if (!state) {
+            usleep(100);
+            curl_multi_do(s);
+        }
+    } while(!state);
+
+    if (state->curl)
+        goto has_curl;
+
+    state->curl = curl_easy_init();
+    if (!state->curl)
+        return NULL;
+    curl_easy_setopt(state->curl, CURLOPT_URL, s->url);
+    curl_easy_setopt(state->curl, CURLOPT_TIMEOUT, 5);
+    curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, curl_read_cb);
+    curl_easy_setopt(state->curl, CURLOPT_WRITEDATA, (void *)state);
+    curl_easy_setopt(state->curl, CURLOPT_PRIVATE, (void *)state);
+    curl_easy_setopt(state->curl, CURLOPT_AUTOREFERER, 1);
+    curl_easy_setopt(state->curl, CURLOPT_FOLLOWLOCATION, 1);
+    curl_easy_setopt(state->curl, CURLOPT_NOSIGNAL, 1);
+    curl_easy_setopt(state->curl, CURLOPT_ERRORBUFFER, state->errmsg);
+    
+#ifdef DEBUG_VERBOSE
+    curl_easy_setopt(state->curl, CURLOPT_VERBOSE, 1);
+#endif
+
+has_curl:
+
+    state->s = s;
+
+    return state;
+}
+
+static void curl_clean_state(CURLState *s)
+{
+    if (s->s->multi)
+        curl_multi_remove_handle(s->s->multi, s->curl);
+    s->in_use = 0;
+}
+
+static int curl_open(BlockDriverState *bs, const char *filename, int flags)
+{
+    BDRVCURLState *s = bs->opaque;
+    CURLState *state = NULL;
+    double d;
+    static int inited = 0;
+
+    if (!inited) {
+        curl_global_init(CURL_GLOBAL_ALL);
+        inited = 1;
+    }
+
+    dprintf("CURL: Opening %s\n", filename);
+    s->url = strdup(filename);
+    state = curl_init_state(s);
+    if (!state)
+        goto out_noclean;
+
+    // Get file size
+
+    curl_easy_setopt(state->curl, CURLOPT_NOBODY, 1);
+    curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, curl_size_cb);
+    if (curl_easy_perform(state->curl))
+        goto out;
+    curl_easy_getinfo(state->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &d);
+    curl_easy_setopt(state->curl, CURLOPT_WRITEFUNCTION, curl_read_cb);
+    curl_easy_setopt(state->curl, CURLOPT_NOBODY, 0);
+    if (d)
+        s->len = (size_t)d;
+    else if(!s->len)
+        goto out;
+    dprintf("CURL: Size = %lld\n", (long long)s->len);
+
+    curl_clean_state(state);
+    curl_easy_cleanup(state->curl);
+    state->curl = NULL;
+
+    // Now we know the file exists and its size, so let's
+    // initialize the multi interface!
+
+    s->multi = curl_multi_init();
+    curl_multi_setopt( s->multi, CURLMOPT_SOCKETDATA, s); 
+    curl_multi_setopt( s->multi, CURLMOPT_SOCKETFUNCTION, curl_sock_cb ); 
+    curl_multi_do(s);
+
+    return 0;
+
+out:
+    fprintf(stderr, "CURL: Error opening file: %s\n", state->errmsg);
+    curl_easy_cleanup(state->curl);
+    state->curl = NULL;
+out_noclean:
+    return -EINVAL;
+}
+
+static BlockDriverAIOCB *curl_aio_readv(BlockDriverState *bs,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockDriverCompletionFunc *cb, void *opaque)
+{
+    BDRVCURLState *s = bs->opaque;
+    CURLAIOCB *acb;
+    size_t start = sector_num * SECTOR_SIZE;
+    size_t end;
+    CURLState *state;
+
+    acb = qemu_aio_get(bs, cb, opaque);
+    if (!acb)
+        return NULL;
+
+    acb->qiov = qiov;
+
+    // In case we have the requested data already (e.g. read-ahead),
+    // we can just call the callback and be done.
+
+    switch (curl_find_buf(s, start, nb_sectors * SECTOR_SIZE, acb)) {
+        case FIND_RET_OK:
+            qemu_aio_release(acb);
+            // fall through
+        case FIND_RET_WAIT:
+            return &acb->common;
+        default:
+            break;
+    }
+
+    // No cache found, so let's start a new request
+
+    state = curl_init_state(s);
+    if (!state)
+        return NULL;
+
+    acb->start = 0;
+    acb->end = (nb_sectors * SECTOR_SIZE);
+
+    state->buf_off = 0;
+    if (state->orig_buf)
+        qemu_free(state->orig_buf);
+    state->buf_start = start;
+    state->buf_len = acb->end + READ_AHEAD_SIZE;
+    end = MIN(start + state->buf_len, s->len) - 1;
+    state->orig_buf = qemu_malloc(state->buf_len);
+    state->acb[0] = acb;
+
+    snprintf(state->range, 127, "%lld-%lld", (long long)start, (long long)end);
+    dprintf("CURL (AIO): Reading %d at %lld (%s)\n", (nb_sectors * SECTOR_SIZE), start, state->range);
+    curl_easy_setopt(state->curl, CURLOPT_RANGE, state->range);
+
+    curl_multi_add_handle(s->multi, state->curl);
+    curl_multi_do(s);
+
+    return &acb->common;
+}
+
+static void curl_aio_cancel(BlockDriverAIOCB *blockacb)
+{
+    // Do we have to implement canceling? Seems to work without...
+}
+
+static void curl_close(BlockDriverState *bs)
+{
+    BDRVCURLState *s = bs->opaque;
+    int i;
+
+    dprintf("CURL: Close\n");
+    for (i=0; i<CURL_NUM_STATES; i++) {
+        if (s->states[i].in_use)
+            curl_clean_state(&s->states[i]);
+        if (s->states[i].curl) {
+            curl_easy_cleanup(s->states[i].curl);
+            s->states[i].curl = NULL;
+        }
+        if (s->states[i].orig_buf) {
+            qemu_free(s->states[i].orig_buf);
+            s->states[i].orig_buf = NULL;
+        }
+    }
+    if (s->multi)
+        curl_multi_cleanup(s->multi);
+    if (s->url)
+        free(s->url);
+}
+
+static int64_t curl_getlength(BlockDriverState *bs)
+{
+    BDRVCURLState *s = bs->opaque;
+    return s->len;
+}
+
+static BlockDriver bdrv_http = {
+    .format_name     = "http",
+    .protocol_name   = "http",
+
+    .instance_size   = sizeof(BDRVCURLState),
+    .bdrv_open       = curl_open,
+    .bdrv_close      = curl_close,
+    .bdrv_getlength  = curl_getlength,
+
+    .aiocb_size      = sizeof(CURLAIOCB),
+    .bdrv_aio_readv  = curl_aio_readv,
+    .bdrv_aio_cancel = curl_aio_cancel,
+};
+
+static BlockDriver bdrv_https = {
+    .format_name     = "https",
+    .protocol_name   = "https",
+
+    .instance_size   = sizeof(BDRVCURLState),
+    .bdrv_open       = curl_open,
+    .bdrv_close      = curl_close,
+    .bdrv_getlength  = curl_getlength,
+
+    .aiocb_size      = sizeof(CURLAIOCB),
+    .bdrv_aio_readv  = curl_aio_readv,
+    .bdrv_aio_cancel = curl_aio_cancel,
+};
+
+static BlockDriver bdrv_ftp = {
+    .format_name     = "ftp",
+    .protocol_name   = "ftp",
+
+    .instance_size   = sizeof(BDRVCURLState),
+    .bdrv_open       = curl_open,
+    .bdrv_close      = curl_close,
+    .bdrv_getlength  = curl_getlength,
+
+    .aiocb_size      = sizeof(CURLAIOCB),
+    .bdrv_aio_readv  = curl_aio_readv,
+    .bdrv_aio_cancel = curl_aio_cancel,
+};
+
+static BlockDriver bdrv_ftps = {
+    .format_name     = "ftps",
+    .protocol_name   = "ftps",
+
+    .instance_size   = sizeof(BDRVCURLState),
+    .bdrv_open       = curl_open,
+    .bdrv_close      = curl_close,
+    .bdrv_getlength  = curl_getlength,
+
+    .aiocb_size      = sizeof(CURLAIOCB),
+    .bdrv_aio_readv  = curl_aio_readv,
+    .bdrv_aio_cancel = curl_aio_cancel,
+};
+
+static BlockDriver bdrv_tftp = {
+    .format_name     = "tftp",
+    .protocol_name   = "tftp",
+
+    .instance_size   = sizeof(BDRVCURLState),
+    .bdrv_open       = curl_open,
+    .bdrv_close      = curl_close,
+    .bdrv_getlength  = curl_getlength,
+
+    .aiocb_size      = sizeof(CURLAIOCB),
+    .bdrv_aio_readv  = curl_aio_readv,
+    .bdrv_aio_cancel = curl_aio_cancel,
+};
+
+static void curl_block_init(void)
+{
+    bdrv_register(&bdrv_http);
+    bdrv_register(&bdrv_https);
+    bdrv_register(&bdrv_ftp);
+    bdrv_register(&bdrv_ftps);
+    bdrv_register(&bdrv_tftp);
+}
+
+block_init(curl_block_init);