diff options
Diffstat (limited to 'types-message.c')
| -rw-r--r-- | types-message.c | 561 |
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; + } +} |