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/* lib9p/9p.c - Base 9P protocol utilities for both clients and servers
*
* Copyright (C) 2024 Luke T. Shumaker <lukeshu@lukeshu.com>
* SPDX-Licence-Identifier: AGPL-3.0-or-later
*/
#include <inttypes.h> /* for PRIu{n} */
#include <stdarg.h> /* for va_* */
#include <stdio.h> /* for vsnprintf() */
#include <string.h> /* for strncpy() */
#include <lib9p/9p.h>
#include "internal.h"
enum lib9p_version lib9p_ctx_version(lib9p_ctx *ctx) {
assert(ctx);
return ctx->version;
}
uint32_t lib9p_ctx_max_msg_size(lib9p_ctx *ctx) {
assert(ctx);
return ctx->max_msg_size;
}
int lib9p_error(struct lib9p_ctx *ctx, uint32_t linux_errno, char const *msg) {
strncpy(ctx->err_msg, msg, sizeof(ctx->err_msg));
ctx->err_msg[sizeof(ctx->err_msg)-1] = '\0';
ctx->err_num = linux_errno;
return -1;
}
int lib9p_errorf(struct lib9p_ctx *ctx, uint32_t linux_errno, char const *fmt, ...) {
int n;
va_list args;
va_start(args, fmt);
n = vsnprintf(ctx->err_msg, sizeof(ctx->err_msg), fmt, args);
va_end(args);
if ((size_t)(n+1) < sizeof(ctx->err_msg))
memset(&ctx->err_msg[n+1], 0, sizeof(ctx->err_msg)-(n+1));
ctx->err_num = linux_errno;
return -1;
}
size_t lib9p_unmarshal_size(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
/* Header */
uint32_t net_len = decode_u32le(net_bytes);
if (net_len < 7)
return lib9p_error(ctx, LINUX_EBADMSG, "message is too short");
uint8_t typ = net_bytes[4];
uint32_t net_offset = 7;
/* Body */
if (!versions[ctx->version]->msgs[typ].unmarshal_extrasize)
return lib9p_errorf(ctx, LINUX_EOPNOTSUPP, "unknown message type %"PRIu8, typ);
size_t host_size = versions[ctx->version]->msgs[typ].unmarshal_basesize;
if (versions[ctx->version]->msgs[typ].unmarshal_extrasize(net_len, net_bytes, &net_offset, &host_size))
return lib9p_error(ctx, LINUX_EBADMSG, "message is too short for content");
return host_size;
}
uint8_t lib9p_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes, uint16_t *out_tag, void *out_body) {
/* Header */
uint8_t typ = net_bytes[4];
*out_tag = decode_u16le(&net_bytes[5]);
uint32_t net_offset = 7;
/* Body */
void *host_extra = out_body + versions[ctx->version]->msgs[typ].unmarshal_basesize;
if (versions[ctx->version]->msgs[typ].unmarshal(net_bytes, &net_offset, &host_extra, out_body))
return lib9p_error(ctx, LINUX_EBADMSG, "message contains invalid UTF-8");
return typ;
}
uint32_t lib9p_marshal(struct lib9p_ctx *ctx, uint8_t typ, uint16_t msgid, void *body, uint8_t *out_bytes) {
/* Header */
out_bytes[4] = typ;
encode_u16le(msgid, &out_bytes[5]);
uint32_t net_offset = 7;
/* Body */
if (versions[ctx->version]->msgs[typ].marshal(ctx, body, out_bytes, &net_offset))
return 0;
/* Header, again */
encode_u32le(net_offset, out_bytes);
return net_offset;
}
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