/* Copyright (c) 2017 - 2020 LiteSpeed Technologies Inc. See LICENSE. */ /* * lsquic_varint.c -- routines dealing with IETF QUIC varint. */ #include #include #include #include "lsquic_byteswap.h" #include "lsquic_varint.h" /* Returns number of bytes read from p (1, 2, 4, or 8), or a negative * value on error. */ int lsquic_varint_read (const unsigned char *p, const unsigned char *end, uint64_t *valp) { uint64_t val; if (p >= end) return -1; switch (*p >> 6) { case 0: *valp = *p; return 1; case 1: if (p + 1 >= end) return -1; *valp = (p[0] & VINT_MASK) << 8 | p[1] ; return 2; case 2: if (p + 3 >= end) return -1; *valp = (p[0] & VINT_MASK) << 24 | p[1] << 16 | p[2] << 8 | p[3] << 0 ; return 4; default: if (p + 7 >= end) return -1; memcpy(&val, p, 8); #if __BYTE_ORDER == __LITTLE_ENDIAN val = bswap_64(val); #endif val &= (1ULL << 62) - 1; *valp = val; return 8; } } int lsquic_varint_read_nb (const unsigned char **pp, const unsigned char *end, struct varint_read_state *state) { const unsigned char *p = *pp; if (p >= end) return -1; switch (state->pos ? state->pos : *p >> 6) { case 0: state->val = *p++; *pp = p; return 0; case 1: state->val = (*p++ & VINT_MASK) << 8; if (p >= end) { state->pos = 1000; break; } /* fall through */ case 1000: state->val |= *p++; *pp = p; return 0; case 2: if (p + 3 < end) { state->val = (p[0] & VINT_MASK) << 24 | p[1] << 16 | p[2] << 8 | p[3] << 0 ; *pp += 4; return 0; } state->val = (*p++ & VINT_MASK) << 24; if (p >= end) { state->pos = 1001; break; } /* fall through */ case 1001: state->val |= *p++ << 16; if (p >= end) { state->pos = 1002; break; } /* fall through */ case 1002: state->val |= *p++ << 8; if (p >= end) { state->pos = 1003; break; } /* fall through */ case 1003: state->val |= *p++; *pp = p; return 0; case 3: if (p + 7 < end) { memcpy(&state->val, p, 8); #if __BYTE_ORDER == __LITTLE_ENDIAN state->val = bswap_64(state->val); #endif state->val &= (1ULL << 62) - 1; *pp += 8; return 0; } state->val = (uint64_t) (*p++ & VINT_MASK) << 56; if (p >= end) { state->pos = 1004; break; } /* fall through */ case 1004: state->val |= (uint64_t) *p++ << 48; if (p >= end) { state->pos = 1005; break; } /* fall through */ case 1005: state->val |= (uint64_t) *p++ << 40; if (p >= end) { state->pos = 1006; break; } /* fall through */ case 1006: state->val |= (uint64_t) *p++ << 32; if (p >= end) { state->pos = 1007; break; } /* fall through */ case 1007: state->val |= (uint64_t) *p++ << 24; if (p >= end) { state->pos = 1008; break; } /* fall through */ case 1008: state->val |= (uint64_t) *p++ << 16; if (p >= end) { state->pos = 1009; break; } /* fall through */ case 1009: state->val |= (uint64_t) *p++ << 8; if (p >= end) { state->pos = 1010; break; } /* fall through */ case 1010: state->val |= *p++; *pp = p; return 0; default: assert(0); } *pp = p; return -1; } int lsquic_varint_read_two (const unsigned char **begin, const unsigned char *end, struct varint_read2_state *state) { const unsigned char *p = *begin; int s; while (p < end) { switch (state->vr2s_state) { case VR2S_READ_ONE_BEGIN: state->vr2s_varint_state.pos = 0; state->vr2s_state = VR2S_READ_ONE_CONTINUE; goto cont; case VR2S_READ_TWO_BEGIN: state->vr2s_varint_state.pos = 0; state->vr2s_state = VR2S_READ_TWO_CONTINUE; goto cont; cont: case VR2S_READ_ONE_CONTINUE: case VR2S_READ_TWO_CONTINUE: s = lsquic_varint_read_nb(&p, end, &state->vr2s_varint_state); if (s == 0) { if (state->vr2s_state == VR2S_READ_TWO_CONTINUE) goto done; state->vr2s_one = state->vr2s_varint_state.val; state->vr2s_state = VR2S_READ_TWO_BEGIN; break; } else goto more; } } more: *begin = p; return -1; done: *begin = p; return 0; }