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authorMattias Andrée <maandree@kth.se>2019-10-22 15:04:45 +0200
committerMattias Andrée <maandree@kth.se>2019-10-22 15:04:45 +0200
commitb13efce73e506b0feb4bb7c275c273a54ae6e716 (patch)
tree79f93e69b01d236e96037aa60332d214696e048b /types-message.c
parentFix NULL-pointer bug in get_pathname when running with -mdrm (diff)
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Change license and style, reorganise file, make makefile portable, and fix bugs1.3
Signed-off-by: Mattias Andrée <maandree@kth.se>
Diffstat (limited to 'types-message.c')
-rw-r--r--types-message.c561
1 files changed, 561 insertions, 0 deletions
diff --git a/types-message.c b/types-message.c
new file mode 100644
index 0000000..de5644d
--- /dev/null
+++ b/types-message.c
@@ -0,0 +1,561 @@
+/* See LICENSE file for copyright and license details. */
+#include "types-message.h"
+#include "util.h"
+
+#include <sys/socket.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+/**
+ * Initialise a message slot so that it can
+ * be used by to read messages
+ *
+ * @param this Memory slot in which to store the new message
+ * @return Non-zero on error, `errno` will be set accordingly
+ */
+int
+message_initialise(struct message *restrict this)
+{
+ this->headers = NULL;
+ this->header_count = 0;
+ this->payload = NULL;
+ this->payload_size = 0;
+ this->payload_ptr = 0;
+ this->buffer_size = 128;
+ this->buffer_ptr = 0;
+ this->stage = 0;
+ this->buffer = malloc(this->buffer_size);
+ if (!this->buffer)
+ return -1;
+ return 0;
+}
+
+
+/**
+ * Release all resources in a message, should
+ * be done even if initialisation fails
+ *
+ * @param this The message
+ */
+void
+message_destroy(struct message *restrict this)
+{
+ size_t i;
+
+ if (this->headers) {
+ for (i = 0; i < this->header_count; i++)
+ free(this->headers[i]);
+ free(this->headers);
+ }
+ free(this->payload);
+ free(this->buffer);
+}
+
+
+#if defined(__clang__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wcast-align"
+#endif
+
+
+/**
+ * Marshal a message for state serialisation
+ *
+ * @param this The message
+ * @param buf Output buffer for the marshalled data,
+ * `NULL` just measure how large the buffers
+ * needs to be
+ * @return The number of marshalled byte
+ */
+size_t
+message_marshal(const struct message *restrict this, void *restrict buf)
+{
+ size_t i, n, off = 0;
+ char *bs = buf;
+
+ if (bs)
+ *(size_t *)&bs[off] = this->header_count;
+ off += sizeof(size_t);
+
+ if (bs)
+ *(size_t *)&bs[off] = this->payload_size;
+ off += sizeof(size_t);
+
+ if (bs)
+ *(size_t *)&bs[off] = this->payload_ptr;
+ off += sizeof(size_t);
+
+ if (bs)
+ *(size_t *)&bs[off] = this->buffer_ptr;
+ off += sizeof(size_t);
+
+ if (bs)
+ *(int *)&bs[off] = this->stage;
+ off += sizeof(int);
+
+ for (i = 0; i < this->header_count; i++) {
+ n = strlen(this->headers[i]) + 1;
+ if (bs)
+ memcpy(&bs[off], this->headers[i], n);
+ off += n;
+ }
+
+ if (bs)
+ memcpy(&bs[off], this->payload, this->payload_ptr);
+ off += this->payload_ptr;
+
+ if (bs)
+ memcpy(&bs[off], this->buffer, this->buffer_ptr);
+ off += this->buffer_ptr;
+
+ return off;
+}
+
+
+/**
+ * Unmarshal a message for state deserialisation
+ *
+ * @param this Memory slot in which to store the new message
+ * @param buf In buffer with the marshalled data
+ * @return The number of unmarshalled bytes, 0 on error
+ */
+size_t
+message_unmarshal(struct message *restrict this, const void *restrict buf)
+{
+ size_t i, n, off = 0, header_count;
+ const char *bs = buf;
+
+ this->header_count = 0;
+
+ header_count = *(const size_t *)&bs[off];
+ off += sizeof(size_t);
+
+ this->payload_size = *(const size_t *)&bs[off];
+ off += sizeof(size_t);
+
+ this->payload_ptr = *(const size_t *)&bs[off];
+ off += sizeof(size_t);
+
+ this->buffer_size = this->buffer_ptr = *(const size_t *)&bs[off];
+ off += sizeof(size_t);
+
+ this->stage = *(const int *)&bs[off];
+ off += sizeof(int);
+
+ /* Make sure that the pointers are NULL so that they are
+ not freed without being allocated when the message is
+ destroyed if this function fails. */
+ this->headers = NULL;
+ this->payload = NULL;
+ this->buffer = NULL;
+
+ /* To 2-power-multiple of 128 bytes. */
+ this->buffer_size >>= 7;
+ if (!this->buffer_size) {
+ this->buffer_size = 1;
+ } else {
+ this->buffer_size -= 1;
+ this->buffer_size |= this->buffer_size >> 1;
+ this->buffer_size |= this->buffer_size >> 2;
+ this->buffer_size |= this->buffer_size >> 4;
+ this->buffer_size |= this->buffer_size >> 8;
+ this->buffer_size |= this->buffer_size >> 16;
+#if SIZE_MAX == UINT64_MAX
+ this->buffer_size |= this->buffer_size >> 32;
+#endif
+ this->buffer_size += 1;
+ }
+ this->buffer_size <<= 7;
+
+ /* Allocate header list, payload and read buffer. */
+
+ if (header_count > 0)
+ if (!(this->headers = malloc(header_count * sizeof(char*))))
+ goto fail;
+
+ if (this->payload_size > 0)
+ if (!(this->payload = malloc(this->payload_size)))
+ goto fail;
+
+ if (!(this->buffer = malloc(this->buffer_size)))
+ goto fail;
+
+ /* Fill the header list, payload and read buffer. */
+
+ for (i = 0; i < header_count; i++) {
+ n = strlen(&bs[off]) + 1;
+ this->headers[i] = memdup(&bs[off], n);
+ if (!this->headers[i])
+ goto fail;
+ off += n;
+ this->header_count++;
+ }
+
+ memcpy(this->payload, &bs[off], this->payload_ptr);
+ off += this->payload_ptr;
+
+ memcpy(this->buffer, &bs[off], this->buffer_ptr);
+ off += this->buffer_ptr;
+
+ return off;
+
+fail:
+ return 0;
+}
+
+
+#if defined(__clang__)
+# pragma GCC diagnostic pop
+#endif
+
+
+
+/**
+ * Extend the header list's allocation
+ *
+ * @param this The message
+ * @param extent The number of additional entries
+ * @return Zero on success, -1 on error
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static int
+extend_headers(struct message *restrict this, size_t extent)
+{
+ char **new = realloc(this->headers, (this->header_count + extent) * sizeof(char *));
+ if (!new)
+ return -1;
+ this->headers = new;
+ return 0;
+}
+
+
+/**
+ * Extend the read buffer by way of doubling
+ *
+ * @param this The message
+ * @return Zero on success, -1 on error
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static int
+extend_buffer(struct message *restrict this)
+{
+ char *restrict new = realloc(this->buffer, (this->buffer_size << 1) * sizeof(char));
+ if (!new)
+ return -1;
+ this->buffer = new;
+ this->buffer_size <<= 1;
+ return 0;
+}
+
+
+/**
+ * Reset the header list and the payload
+ *
+ * @param this The message
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static void
+reset_message(struct message *restrict this)
+{
+ size_t i;
+ if (this->headers) {
+ for (i = 0; i < this->header_count; i++)
+ free(this->headers[i]);
+ free(this->headers);
+ this->headers = NULL;
+ }
+ this->header_count = 0;
+
+ free(this->payload);
+ this->payload = NULL;
+ this->payload_size = 0;
+ this->payload_ptr = 0;
+}
+
+
+/**
+ * Read the headers the message and determine, and store, its payload's length
+ *
+ * @param this The message
+ * @return Zero on success, negative on error (malformated message: unrecoverable state)
+ */
+GCC_ONLY(__attribute__((__pure__, __nonnull__)))
+static int
+get_payload_length(struct message *restrict this)
+{
+ char *header;
+ size_t i;
+
+ for (i = 0; i < this->header_count; i++) {
+ if (strstr(this->headers[i], "Length: ") == this->headers[i]) {
+ /* Store the message length. */
+ header = this->headers[i] + strlen("Length: ");
+ this->payload_size = (size_t)atol(header);
+
+ /* Do not except a length that is not correctly formated. */
+ for (; *header; header++)
+ if (*header < '0' || '9' < *header)
+ return -2; /* Malformated value, enters unrecoverable state. */
+
+ /* Stop searching for the ‘Length’ header, we have found and parsed it. */
+ break;
+ }
+ }
+
+ return 0;
+}
+
+
+/**
+ * Verify that a header is correctly formatted
+ *
+ * @param header The header, must be NUL-terminated
+ * @param length The length of the header
+ * @return Zero if valid, negative if invalid (malformated message: unrecoverable state)
+ */
+GCC_ONLY(__attribute__((__pure__, __nonnull__)))
+static int
+validate_header(const char *restrict header, size_t length)
+{
+ char *restrict p = memchr(header, ':', length * sizeof(char));
+
+ if (verify_utf8(header) < 0) {
+ /* Either the string is not UTF-8, or your are under an UTF-8 attack,
+ let's just call this unrecoverable because the client will not correct. */
+ return -2;
+ }
+
+ if (!p || /* Buck you, rawmemchr should not segfault the program. */
+ p[1] != ' ') /* Also an invalid format. ' ' is mandated after the ':'. */
+ return -2;
+
+ return 0;
+}
+
+
+/**
+ * Remove the beginning of the read buffer
+ *
+ * @param this The message
+ * @param length The number of characters to remove
+ * @param update_ptr Whether to update the buffer pointer
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static void
+unbuffer_beginning(struct message *restrict this, size_t length, int update_ptr)
+{
+ memmove(this->buffer, &this->buffer[length], (this->buffer_ptr - length) * sizeof(char));
+ if (update_ptr)
+ this->buffer_ptr -= length;
+}
+
+
+/**
+ * Remove the header–payload delimiter from the buffer,
+ * get the payload's size and allocate the payload
+ *
+ * @param this The message
+ * @return The return value follows the rules of `message_read`
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static int
+initialise_payload(struct message *restrict this)
+{
+ /* Remove the \n (end of empty line) we found from the buffer. */
+ unbuffer_beginning(this, 1, 1);
+
+ /* Get the length of the payload. */
+ if (get_payload_length(this) < 0)
+ return -2; /* Malformated value, enters unrecoverable state. */
+
+ /* Allocate the payload buffer. */
+ if (this->payload_size > 0) {
+ this->payload = malloc(this->payload_size);
+ if (!this->payload)
+ return -1;
+ }
+
+ return 0;
+}
+
+
+/**
+ * Create a header from the buffer and store it
+ *
+ * @param this The message
+ * @param length The length of the header, including LF-termination
+ * @return The return value follows the rules of `message_read`
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static int
+store_header(struct message *restrict this, size_t length)
+{
+ char *restrict header;
+
+ /* Allocate the header. */
+ header = malloc(length); /* Last char is a LF, which is substituted with NUL. */
+ if (!header)
+ return -1;
+ /* Copy the header data into the allocated header, */
+ memcpy(header, this->buffer, length * sizeof(char));
+ /* and NUL-terminate it. */
+ header[length - 1] = '\0';
+
+ /* Remove the header data from the read buffer. */
+ unbuffer_beginning(this, length, 1);
+
+ /* Make sure the the header syntax is correct so that
+ the program does not need to care about it. */
+ if (validate_header(header, length)) {
+ free(header);
+ return -2;
+ }
+
+ /* Store the header in the header list. */
+ this->headers[this->header_count++] = header;
+
+ return 0;
+}
+
+
+/**
+ * Continue reading from the socket into the buffer
+ *
+ * @param this The message
+ * @param fd The file descriptor of the socket
+ * @return The return value follows the rules of `message_read`
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static int
+continue_read(struct message *restrict this, int fd)
+{
+ size_t n;
+ ssize_t got;
+ int r;
+
+ /* Figure out how much space we have left in the read buffer. */
+ n = this->buffer_size - this->buffer_ptr;
+
+ /* If we do not have too much left, */
+ if (n < 128) {
+ /* grow the buffer, */
+ if ((r = extend_buffer(this)) < 0)
+ return r;
+
+ /* and recalculate how much space we have left. */
+ n = this->buffer_size - this->buffer_ptr;
+ }
+
+ /* Then read from the socket. */
+ errno = 0;
+ got = recv(fd, this->buffer + this->buffer_ptr, n, 0);
+ this->buffer_ptr += (size_t)(got < 0 ? 0 : got);
+ if (errno)
+ return -1;
+ if (got == 0) {
+ errno = ECONNRESET;
+ return -1;
+ }
+
+ return 0;
+}
+
+
+/**
+ * Read the next message from a file descriptor
+ *
+ * @param this Memory slot in which to store the new message
+ * @param fd The file descriptor
+ * @return 0: At least one message is available
+ * -1: Exceptional connection:
+ * EINTR: System call interrupted
+ * EAGAIN: No message is available
+ * EWOULDBLOCK: No message is available
+ * ECONNRESET: Connection closed
+ * Other: Failure
+ * -2: Corrupt message (unrecoverable)
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+int
+message_read(struct message *restrict this, int fd)
+{
+ size_t header_commit_buffer = 0;
+ size_t length, need, move;
+ int r;
+ char *p;
+
+ /* If we are at stage 2, we are done and it is time to start over.
+ This is important because the function could have been interrupted. */
+ if (this->stage == 2) {
+ reset_message(this);
+ this->stage = 0;
+ }
+
+ /* Read from file descriptor until we have a full message. */
+ for (;;) {
+ /* Stage 0: headers. */
+ /* Read all headers that we have stored into the read buffer. */
+ while (this->stage == 0 &&
+ ((p = memchr(this->buffer, '\n', this->buffer_ptr * sizeof(char))))) {
+ length = (size_t)(p - this->buffer);
+ if (length) {
+ /* We have found a header. */
+
+ /* On every eighth header found with this function call,
+ we prepare the header list for eight more headers so
+ that it does not need to be reallocated again and again. */
+ if (!header_commit_buffer)
+ if ((r = extend_headers(this, header_commit_buffer = 8)) < 0)
+ return r;
+
+ /* Create and store header. */
+ if ((r = store_header(this, length + 1)) < 0)
+ return r;
+ header_commit_buffer -= 1;
+ } else {
+ /* We have found an empty line, i.e. the end of the headers. */
+
+ /* Remove the header–payload delimiter from the buffer,
+ get the payload's size and allocate the payload. */
+ if ((r = initialise_payload(this)) < 0)
+ return r;
+
+ /* Mark end of stage, next stage is getting the payload. */
+ this->stage = 1;
+ }
+ }
+
+
+ /* Stage 1: payload. */
+ if ((this->stage == 1) && (this->payload_size > 0)) {
+ /* How much of the payload that has not yet been filled. */
+ need = this->payload_size - this->payload_ptr;
+ /* How much we have of that what is needed. */
+ move = this->buffer_ptr < need ? this->buffer_ptr : need;
+
+ /* Copy what we have, and remove it from the the read buffer. */
+ memcpy(&this->payload[this->payload_ptr], this->buffer, move * sizeof(char));
+ unbuffer_beginning(this, move, 1);
+
+ /* Keep track of how much we have read. */
+ this->payload_ptr += move;
+ }
+ if (this->stage == 1 && this->payload_ptr == this->payload_size) {
+ /* If we have filled the payload (or there was no payload),
+ mark the end of this stage, i.e. that the message is
+ complete, and return with success. */
+ this->stage = 2;
+ return 0;
+ }
+
+
+ /* If stage 1 was not completed. */
+
+ /* Continue reading from the socket into the buffer. */
+ if ((r = continue_read(this, fd)) < 0)
+ return r;
+ }
+}