diff --git a/src/fcgi.c b/src/fcgi.c
new file mode 100644
index 0000000..33aa2a2
--- /dev/null
+++ b/src/fcgi.c
@@ -0,0 +1,293 @@
+/*
+ * FastCGI protocol processing
+ *
+ * Copyright (C) 2019 HAProxy Technologies, Christopher Faulet <cfaulet@haproxy.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <common/fcgi.h>
+
+
+/* Encodes header of a FCGI record into the chunk <out>. It returns non-zero on
+ * success and 0 on failure (buffer full). <out> is a chunk, so the wrapping is
+ * not handled by this function. It is the caller responsibility to ensure
+ * enough contiguous space is available
+ */
+int fcgi_encode_record_hdr(struct buffer *out, const struct fcgi_header *h)
+{
+	size_t len = out->data;
+
+	if (len + 8 >= b_size(out))
+		return 0;
+
+	out->area[len++] = h->vsn;
+	out->area[len++] = h->type;
+	out->area[len++] = ((h->id >> 8) & 0xff);
+	out->area[len++] = (h->id & 0xff);
+	out->area[len++] = ((h->len >> 8) & 0xff);
+	out->area[len++] = (h->len & 0xff);
+	out->area[len++] = h->padding;
+	len++; /* rsv */
+
+	out->data = len;
+	return 1;
+}
+
+/* Decodes a FCGI record header from offset <o> of buffer <in> into descriptor
+ * <h>. The buffer may wrap so each byte read must be checked. The header is
+ * formed like this :
+ *
+ *     b0    b1     b2    b3    b4      b5     b6      b7
+ *  +-----+------+-----+-----+------+------+--------+-----+
+ *  | vsn | type | id1 | id0 | len1 | len0 | padlen | rsv |
+ *  +-----+------+-----+-----+------+------+--------+-----+
+ *
+ * Returns zero if some bytes are missing, otherwise the number of read bytes.
+ */
+size_t fcgi_decode_record_hdr(const struct buffer *in, size_t o, struct fcgi_header *h)
+{
+	if (b_data(in) < o + 8)
+		return 0;
+
+	h->vsn     = (uint8_t)(*b_peek(in, o));
+	h->type    = (uint8_t)(*b_peek(in, o+1));
+	h->id      = ((uint8_t)(*b_peek(in, o+2)) << 8) + (uint8_t)(*b_peek(in, o+3));
+	h->len     = ((uint8_t)(*b_peek(in, o+4)) << 8) + (uint8_t)(*b_peek(in, o+5));
+	h->padding = (uint8_t)(*b_peek(in, o+6));
+	/* ignore rsv */
+
+	return 8;
+}
+
+/* Encodes the payload part of a BEGIN_REQUEST record into the chunk <out>. It
+ * returns non-zero on success and 0 on failure (buffer full). <out> is a chunk,
+ * so the wrapping is not handled by this function. It is the caller
+ * responsibility to ensure enough contiguous space is available
+ */
+int fcgi_encode_begin_request(struct buffer *out, const struct fcgi_begin_request *r)
+{
+	size_t len = out->data;
+
+	if (len + 8 >= b_size(out))
+		return 0;
+
+	out->area[len++] = ((r->role >> 8) & 0xff);
+	out->area[len++] = (r->role & 0xff);
+	out->area[len++] = r->flags;
+	len += 5; /* rsv */
+
+	out->data = len;
+	return 1;
+}
+
+/* Encodes a parameter, part of the payload of a PARAM record, into the chunk
+ * <out>. It returns non-zero on success and 0 on failure (buffer full). <out>
+ * is a chunk, so the wrapping is not handled by this function. It is the caller
+ * responsibility to ensure enough contiguous space is available. The
+ * parameter's name is converted to upper case and non-alphanumeric character
+ * are replaced by an underscore.
+ */
+int fcgi_encode_param(struct buffer *out, const struct fcgi_param *p)
+{
+	size_t off, len = out->data;
+	int nbytes, vbytes;
+
+	nbytes = (!(p->n.len >> 7) ? 1 : 4);
+	vbytes = (!(p->v.len >> 7) ? 1 : 4);
+	if ((len + nbytes + p->n.len + vbytes + p->v.len) >= b_size(out))
+		return 0;
+
+	if (nbytes == 1)
+		out->area[len++] = (p->n.len & 0xff);
+	else {
+		out->area[len++] = (((p->n.len >> 24) & 0xff) | 0x80);
+		out->area[len++] = ((p->n.len >> 16) & 0xff);
+		out->area[len++] = ((p->n.len >> 8) & 0xff);
+		out->area[len++] = (p->n.len & 0xff);
+	}
+
+	if (vbytes == 1)
+		out->area[len++] = (p->v.len & 0xff);
+	else {
+		out->area[len++] = (((p->v.len >> 24) & 0xff) | 0x80);
+		out->area[len++] = ((p->v.len >> 16) & 0xff);
+		out->area[len++] = ((p->v.len >> 8) & 0xff);
+		out->area[len++] = (p->v.len & 0xff);
+	}
+
+	for (off = 0; off < p->n.len; off++) {
+		if (isalnum((int)p->n.ptr[off]))
+			out->area[len++] = ist_uc[(unsigned char)p->n.ptr[off]];
+		else
+			out->area[len++] = '_';
+	}
+	if (p->v.len) {
+		ist2bin(out->area + len, p->v);
+		len += p->v.len;
+	}
+
+	out->data = len;
+	return 1;
+}
+
+/* Decodes a parameter of a PARAM record from offset <o> of buffer <in> into the
+ * FCGI param <p>. The buffer may wrap so each byte read must be checked.
+ * Returns zero if some bytes are missing, otherwise the number of read bytes.
+ */
+size_t fcgi_decode_param(const struct buffer *in, size_t o, struct fcgi_param *p)
+{
+	size_t data = b_data(in);
+	size_t nlen, vlen, len = 0;
+	uint8_t b0, b1, b2, b3;
+
+	if (data < o + 1)
+		return 0;
+	b0 = *b_peek(in, o++);
+	if (!(b0 >> 7)) {
+		nlen = b0;
+		len++;
+	}
+	else {
+		if (data < o + 3)
+			return 0;
+		b1 = *b_peek(in, o++);
+		b2 = *b_peek(in, o++);
+		b3 = *b_peek(in, o++);
+		nlen = ((b0 & 0x7f) << 24) + (b1 << 16) + (b2 << 8) + b3;
+		len += 4;
+	}
+
+	if (data < o + 1)
+		return 0;
+	b0 = *b_peek(in, o++);
+	if (!(b0 >> 7)) {
+		vlen = b0;
+		len++;
+	}
+	else {
+		if (data < o + 3)
+			return 0;
+		b1 = *b_peek(in, o++);
+		b2 = *b_peek(in, o++);
+		b3 = *b_peek(in, o++);
+		vlen = ((b0 & 0x7f) << 24) + (b1 << 16) + (b2 << 8) + b3;
+		len += 4;
+	}
+
+	if (data < nlen + vlen)
+		return 0;
+
+	p->n.ptr = b_peek(in, o);
+	p->n.len = nlen;
+	p->v.ptr = b_peek(in, o+nlen);
+	p->v.len = vlen;
+	len += nlen + vlen;
+
+	return len;
+}
+
+
+/* Decodes a parameter of a PARAM record from offset <o> of buffer <in> into the
+ * FCGI param <p>. To call this function, the buffer must not wrap. Returns zero
+ * if some bytes are missing, otherwise the number of read bytes.
+ */
+size_t fcgi_aligned_decode_param(const struct buffer *in, size_t o, struct fcgi_param *p)
+{
+	size_t data = b_data(in);
+	size_t nlen, vlen, len = 0;
+	uint8_t b0, b1, b2, b3;
+
+	if (data < o + 1)
+		return 0;
+	b0 = in->area[o++];
+	if (!(b0 >> 7)) {
+		nlen = b0;
+		len++;
+	}
+	else {
+		if (data < o + 3)
+			return 0;
+		b1 = in->area[o++];
+		b2 = in->area[o++];
+		b3 = in->area[o++];
+		nlen = ((b0 & 0x7f) << 24) + (b1 << 16) + (b2 << 8) + b3;
+		len += 4;
+	}
+
+	if (data < o + 1)
+		return 0;
+	b0 = in->area[o++];
+	if (!(b0 >> 7)) {
+		vlen = b0;
+		len++;
+	}
+	else {
+		if (data < o + 3)
+			return 0;
+		b1 = in->area[o++];
+		b2 = in->area[o++];
+		b3 = in->area[o++];
+		vlen = ((b0 & 0x7f) << 24) + (b1 << 16) + (b2 << 8) + b3;
+		len += 4;
+	}
+
+	if (data < nlen + vlen)
+		return 0;
+
+	p->n.ptr = in->area + o;
+	p->n.len = nlen;
+	p->v.ptr = in->area + o + nlen;
+	p->v.len = vlen;
+	len += nlen + vlen;
+
+	return len;
+}
+
+/* Decodes payload of a END_REQUEST record from offset <o> of buffer <in> into
+ * the FCGI param <p>. The buffer may wrap so each byte read must be
+ * checked. Returns zero if some bytes are missing, otherwise the number of read
+ * bytes.
+ */
+size_t fcgi_decode_end_request(const struct buffer *in, size_t o, struct fcgi_end_request *rec)
+{
+	uint8_t b0, b1, b2, b3;
+
+	if (b_data(in) < o + 8)
+		return 0;
+
+	b0 = *b_peek(in, o++);
+	b1 = *b_peek(in, o++);
+	b2 = *b_peek(in, o++);
+	b3 = *b_peek(in, o++);
+	rec->status = ((b0 & 0x7f) << 24) + (b1 << 16) + (b2 << 8) + b3;
+	rec->errcode = *b_peek(in, o++);
+        o += 3; /* ignore rsv */
+
+	return 8;
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */