func()

in otr/smp.go [65:159]
89 lines of code
22 McCabe index (conditional complexity)

func (c *Conversation) processSMP(in tlv) (out tlv, complete bool, err error) {
	data := in.data

	switch in.typ {
	case tlvTypeSMPAbort:
		if c.smp.state != smpState1 {
			err = smpFailureError
		}
		c.resetSMP()
		return
	case tlvTypeSMP1WithQuestion:
		// We preprocess this into a SMP1 message.
		nulPos := bytes.IndexByte(data, 0)
		if nulPos == -1 {
			err = errors.New("otr: SMP message with question didn't contain a NUL byte")
			return
		}
		c.smp.question = string(data[:nulPos])
		data = data[nulPos+1:]
	}

	numMPIs, data, ok := getU32(data)
	if !ok || numMPIs > 20 {
		err = errors.New("otr: corrupt SMP message")
		return
	}

	mpis := make([]*big.Int, numMPIs)
	for i := range mpis {
		var ok bool
		mpis[i], data, ok = getMPI(data)
		if !ok {
			err = errors.New("otr: corrupt SMP message")
			return
		}
	}

	switch in.typ {
	case tlvTypeSMP1, tlvTypeSMP1WithQuestion:
		if c.smp.state != smpState1 {
			c.resetSMP()
			out = c.generateSMPAbort()
			return
		}
		if c.smp.secret == nil {
			err = smpSecretMissingError
			return
		}
		if err = c.processSMP1(mpis); err != nil {
			return
		}
		c.smp.state = smpState3
		out = c.generateSMP2()
	case tlvTypeSMP2:
		if c.smp.state != smpState2 {
			c.resetSMP()
			out = c.generateSMPAbort()
			return
		}
		if out, err = c.processSMP2(mpis); err != nil {
			out = c.generateSMPAbort()
			return
		}
		c.smp.state = smpState4
	case tlvTypeSMP3:
		if c.smp.state != smpState3 {
			c.resetSMP()
			out = c.generateSMPAbort()
			return
		}
		if out, err = c.processSMP3(mpis); err != nil {
			return
		}
		c.smp.state = smpState1
		c.smp.secret = nil
		complete = true
	case tlvTypeSMP4:
		if c.smp.state != smpState4 {
			c.resetSMP()
			out = c.generateSMPAbort()
			return
		}
		if err = c.processSMP4(mpis); err != nil {
			out = c.generateSMPAbort()
			return
		}
		c.smp.state = smpState1
		c.smp.secret = nil
		complete = true
	default:
		panic("unknown SMP message")
	}

	return
}