[Qemu-devel] [RFC][PATCH v6 05/23] virtagent: transport definitions read/send callback functions

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 virtagent-common.c |  415 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 virtagent-common.h |    1 +
 2 files changed, 416 insertions(+), 0 deletions(-)

diff --git a/virtagent-common.c b/virtagent-common.c
index c487252..f8b7d74 100644
--- a/virtagent-common.c
+++ b/virtagent-common.c
@@ -177,6 +177,421 @@ static void va_unset_server_timeout(void)
 }
 
 /***********************************************************/
+/* callbacks for read/send handlers */
+
+static void va_client_send_cb(enum va_http_status http_status,
+                              const char *content, size_t content_len)
+{
+    VAClientJob *client_job = va_current_client_job();
+
+    TRACE("called");
+    assert(client_job != NULL);
+
+    if (http_status != VA_HTTP_STATUS_OK) {
+        /* TODO: we should reset everything at this point...guest/host will
+         * be out of whack with each other since there's no way to let the
+         * other know job failed (server or client job) if the send channel
+         * is down. But how do we induce the other side to do the same?
+         */
+        LOG("error sending http request");
+    }
+
+    /* request sent ok. free up request xml, then move to
+     * wait (for response) state
+     */
+    XMLRPC_MEMBLOCK_FREE(char, client_job->req_data);
+    assert(va_set_client_state(VA_CLIENT_WAIT));
+}
+
+static void va_server_send_cb(enum va_http_status http_status,
+                              const char *content, size_t content_len)
+{
+    VAServerJob *server_job = va_pop_server_job();
+
+    TRACE("called");
+    assert(server_job != NULL);
+    va_unset_server_timeout();
+
+    if (http_status != VA_HTTP_STATUS_OK) {
+        /* TODO: we should reset everything at this point...guest/host will
+         * be out of whack with each other since there's no way to let the
+         * other know job failed (server or client job) if the send channel
+         * is down
+         */
+        LOG("error sending http response");
+        return;
+    }
+
+    /* response sent ok, cleanup server job and kick off the next one */
+    XMLRPC_MEMBLOCK_FREE(char, server_job->resp_data);
+    qemu_free(server_job);
+    va_kick();
+}
+
+static void va_client_read_cb(const char *content, size_t content_len,
+                              const char client_tag[64])
+{
+    VAClientJob *client_job;
+
+    TRACE("called");
+    client_job = va_pop_client_job();
+    assert(client_job != NULL);
+    if (--va_state->client_jobs_in_flight == 0) {
+        va_unset_client_timeout();
+    }
+    if (strncmp(client_job->client_tag, client_tag, 64)) {
+        LOG("http client tag mismatch");
+    } else {
+        TRACE("tag matched: %s", client_tag);
+    }
+
+    client_job->cb(content, content_len, client_job->mon_cb,
+                   client_job->mon_data);
+    va_kick();
+}
+
+static void va_server_read_cb(const char *content, size_t content_len,
+                              const char client_tag[64])
+{
+    int ret;
+
+    TRACE("called");
+    /* generate response and queue it up for sending */
+    ret = va_do_server_rpc(content, content_len, client_tag);
+    if (ret != 0) {
+        LOG("error creating handling remote rpc request: %s", strerror(ret));
+    }
+
+    return;
+}
+
+static void va_http_read_cb(enum va_http_status http_status,
+                            const char *content, size_t content_len,
+                            const char client_tag[64],
+                            enum va_http_type http_type)
+{
+    TRACE("called");
+    if (http_status != VA_HTTP_STATUS_OK) {
+        LOG("error reading http stream (type %d)", http_type);
+        va_cancel_jobs();
+        return;
+    }
+
+    if (http_type == VA_HTTP_TYPE_REQUEST) {
+        TRACE("read request: %s", content);
+        va_server_read_cb(content, content_len, client_tag);
+    } else if (http_type == VA_HTTP_TYPE_RESPONSE) {
+        TRACE("read response: %s", content);
+        va_client_read_cb(content, content_len, client_tag);
+    } else {
+        LOG("unknown http response/request type");
+        va_cancel_jobs();
+    }
+
+    return;
+}
+
+/***********************************************************/
+/* utility functions for handling http calls */
+
+static void va_http_hdr_init(VAHTState *s, enum va_http_type http_type) {
+    const char *preamble;
+
+    TRACE("called");
+    /* essentially ignored in the context of virtagent, but might as well */
+    if (http_type == VA_HTTP_TYPE_REQUEST) {
+        preamble = "POST /RPC2 HTTP/1.1";
+    } else if (http_type == VA_HTTP_TYPE_RESPONSE) {
+        preamble = "HTTP/1.1 200 OK";
+    } else {
+        s->hdr_len = 0;
+        return;
+    }
+    memset(s->hdr, 0, VA_HDR_LEN_MAX);
+    s->hdr_len = sprintf(s->hdr,
+                         "%c%s" EOL
+                         "Content-Type: text/xml" EOL
+                         "Content-Length: %u" EOL
+                         "X-Virtagent-Client-Tag: %s" EOL EOL,
+                         VA_SENTINEL,
+                         preamble,
+                         (uint32_t)s->content_len,
+                         s->hdr_client_tag[0] ? s->hdr_client_tag : "none");
+}
+
+#define VA_LINE_LEN_MAX 1024
+static void va_rpc_parse_hdr(VAHTState *s)
+{
+    int i, line_pos = 0;
+    bool first_line = true;
+    char line_buf[VA_LINE_LEN_MAX];
+
+    TRACE("called");
+
+    for (i = 0; i < VA_HDR_LEN_MAX; ++i) {
+        if (s->hdr[i] == 0) {
+            /* end of header */
+            return;
+        }
+        if (s->hdr[i] != '\n') {
+            /* read line */
+            line_buf[line_pos++] = s->hdr[i];
+        } else {
+            /* process line */
+            if (first_line) {
+                if (strncmp(line_buf, "POST", 4) == 0) {
+                    s->http_type = VA_HTTP_TYPE_REQUEST;
+                } else if (strncmp(line_buf, "HTTP", 4) == 0) {
+                    s->http_type = VA_HTTP_TYPE_RESPONSE;
+                } else {
+                    s->http_type = VA_HTTP_TYPE_UNKNOWN;
+                }
+                first_line = false;
+            }
+            if (strncmp(line_buf, "Content-Length: ", 16) == 0) {
+                s->content_len = atoi(&line_buf[16]);
+            }
+            if (strncmp(line_buf, "X-Virtagent-Client-Tag: ", 24) == 0) {
+                memcpy(s->hdr_client_tag, &line_buf[24], MIN(line_pos-25, 64));
+                //pstrcpy(s->hdr_client_tag, 64, &line_buf[24]);
+                TRACE("\nTAG<%s>\n", s->hdr_client_tag);
+            }
+            line_pos = 0;
+            memset(line_buf, 0, VA_LINE_LEN_MAX);
+        }
+    }
+}
+
+static int va_end_of_header(char *buf, int end_pos)
+{
+    return !strncmp(buf+(end_pos-2), "\n\r\n", 3);
+}
+
+static void va_http_read_handler_reset(void)
+{
+    VAHTState *s = &va_state->read_state;
+    TRACE("called");
+    s->state = VA_READ_START;
+    s->http_type = VA_HTTP_TYPE_UNKNOWN;
+    s->hdr_pos = 0;
+    s->content_len = 0;
+    s->content_pos = 0;
+    strcpy(s->hdr_client_tag, "none");
+    if (s->content != NULL) {
+        qemu_free(s->content);
+    }
+    s->content = NULL;
+}
+
+/***********************************************************/
+/* read/send handlers */
+
+static void va_http_read_handler(void *opaque)
+{
+    VAHTState *s = &va_state->read_state;
+    enum va_http_status http_status;
+    int fd = va_state->fd;
+    int ret;
+    uint8_t tmp;
+    static int bytes_skipped = 0;
+
+    TRACE("called with opaque: %p", opaque);
+
+    /* until timeouts are implemented, make sure we kick so any deferred
+     * jobs get a chance to run
+     */
+    va_kick();
+
+    switch (s->state) {
+    case VA_READ_START:
+        /* we may have gotten here due to a http error, indicating
+         * a potential unclean state where we are not 'aligned' on http
+         * boundaries. we should read till we hit the next http preamble
+         * rather than assume we're at the start of an http header. since
+         * we control the transport layer on both sides, we'll use a
+         * more reliable sentinal character to mark/detect the start of
+         * the header
+         */
+        while((ret = read(fd, &tmp, 1) > 0) > 0) {
+            if (tmp == VA_SENTINEL) {
+                break;
+            }
+            bytes_skipped += ret;
+        }
+        if (ret == -1) {
+            if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) {
+                return;
+            } else {
+                LOG("error reading connection: %s", strerror(errno));
+                goto out_bad;
+            }
+        } else if (ret == 0) {
+            LOG("connected closed unexpectedly");
+            goto out_bad_wait;
+        } else {
+            TRACE("found header, number of bytes skipped: %d",
+                  bytes_skipped);
+            bytes_skipped = 0;
+            s->state = VA_READ_HDR;
+        }
+    case VA_READ_HDR:
+        while((ret = read(fd, s->hdr + s->hdr_pos, 1)) > 0
+              && s->hdr_pos < VA_HDR_LEN_MAX) {
+            s->hdr_pos += ret;
+            if (va_end_of_header(s->hdr, s->hdr_pos - 1)) {
+                break;
+            }
+        }
+        if (ret == -1) {
+            if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) {
+                return;
+            } else {
+                LOG("error reading connection: %s", strerror(errno));
+                goto out_bad;
+            }
+        } else if (ret == 0) {
+            LOG("connected closed unexpectedly");
+            goto out_bad_wait;
+        } else if (s->hdr_pos >= VA_HDR_LEN_MAX) {
+            LOG("http header too long");
+            goto out_bad;
+        } else {
+            s->content_len = -1;
+            va_rpc_parse_hdr(s);
+            if (s->content_len == -1) {
+                LOG("malformed http header");
+                goto out_bad;
+            } else if (s->content_len > VA_CONTENT_LEN_MAX) {
+                LOG("http content length too long");
+                goto out_bad;
+            }
+            s->content = qemu_mallocz(s->content_len);
+            s->state = VA_READ_BODY;
+            TRACE("read http header:\n<<<%s>>>\n", s->hdr);
+        }
+    case VA_READ_BODY:
+        while(s->content_pos < s->content_len) {
+            ret = read(fd, s->content + s->content_pos,
+                       s->content_len - s->content_pos);
+            if (ret == -1) {
+                if (errno == EAGAIN || errno == EWOULDBLOCK
+                    || errno == EINTR) {
+                    return;
+                } else {
+                    LOG("error reading connection: %s", strerror(errno));
+                    goto out_bad;
+                }
+            } else if (ret == 0) {
+                LOG("connection closed unexpectedly:"
+                    " read %u bytes, expected %u bytes",
+                    (unsigned int)s->content_pos, (unsigned int)s->content_len);
+                goto out_bad_wait;
+            }
+            s->content_pos += ret;
+        }
+
+        TRACE("read http content:\n<<<%s>>>\n", s->content);
+        http_status = VA_HTTP_STATUS_OK;
+        goto out;
+    default:
+        LOG("unknown state");
+        goto out_bad;
+    }
+
+out_bad_wait:
+    /* We should only ever get a read = 0 if we're using virtio and the host
+     * is not connected. this would cause a guest to spin, and we can't do
+     * any work in the meantime, so sleep for a bit here. We also know we
+     * may go ahead and cancel any outstanding jobs at this point, though it
+     * should be noted that we're still ultimately reliant on per-job timeouts
+     * since we might not read EOF before host reconnect.
+     */
+    if (!va_state->is_host &&
+        strcmp(va_state->channel_method, "virtio-serial") == 0) {
+        usleep(100 * 1000);
+    }
+out_bad:
+    http_status = VA_HTTP_STATUS_ERROR;
+out:
+    /* handle the response or request we just read */
+    s->read_cb(http_status, s->content, s->content_len, s->hdr_client_tag,
+               s->http_type);
+    /* restart read handler */
+    va_http_read_handler_reset();
+    http_status = VA_HTTP_STATUS_NEW;
+}
+
+static void va_http_send_handler(void *opaque)
+{
+    VAHTState *s = &va_state->send_state;
+    enum va_http_status http_status;
+    int fd = va_state->fd;
+    int ret;
+
+    TRACE("called");
+
+    switch (s->state) {
+    case VA_SEND_START:
+        s->state = VA_SEND_HDR;
+    case VA_SEND_HDR:
+        do {
+            ret = write(fd, s->hdr + s->hdr_pos, s->hdr_len - s->hdr_pos);
+            if (ret <= 0) {
+                break;
+            }
+            s->hdr_pos += ret;
+        } while (s->hdr_pos < s->hdr_len);
+        if (ret == -1) {
+            if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) {
+                return;
+            } else {
+                LOG("error writing header: %s", strerror(errno));
+                goto out_bad;
+            }
+        } else if (ret == 0) {
+            LOG("connected closed unexpectedly");
+            goto out_bad;
+        } else {
+            s->state = VA_SEND_BODY;
+            TRACE("sent http header:\n<<<%s>>>", s->hdr);
+        }
+    case VA_SEND_BODY:
+        do {
+            ret = write(fd, s->content + s->content_pos,
+                        s->content_len - s->content_pos);
+            if (ret <= 0) {
+                break;
+            }
+            s->content_pos += ret;
+        } while (s->content_pos < s->content_len);
+        if (ret == -1) {
+            if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) {
+                return;
+            } else {
+                LOG("error writing content: %s", strerror(errno));
+                goto out_bad;
+            }
+        } else if (ret == 0) {
+            LOG("connected closed unexpectedly");
+            goto out_bad;
+        } else {
+            http_status = VA_HTTP_STATUS_OK;
+            TRACE("set http content:\n<<<%s>>>", s->content);
+            goto out;
+        }
+    default:
+        LOG("unknown state");
+        goto out_bad;
+    }
+
+out_bad:
+    http_status = VA_HTTP_STATUS_ERROR;
+out:
+    s->send_cb(http_status, s->content, s->content_len);
+    qemu_set_fd_handler(fd, va_http_read_handler, NULL, NULL);
+}
+
+/***********************************************************/
 /* functions for starting/managing client/server rpc jobs */
 
 static int va_send_server_response(VAServerJob *server_job)
diff --git a/virtagent-common.h b/virtagent-common.h
index 568df5a..6ad8036 100644
--- a/virtagent-common.h
+++ b/virtagent-common.h
@@ -50,6 +50,7 @@
 #define VA_SERVER_JOBS_MAX 5 /* max server rpcs we can queue */
 #define VA_SERVER_TIMEOUT_MS 5 * 1000
 #define VA_CLIENT_TIMEOUT_MS 5 * 1000
+#define VA_SENTINEL 0xFF
 
 typedef struct VAContext {
     bool is_host;
-- 
1.7.0.4